BETS-4 — Technical Standards and Requirements for Television Broadcasting Transmitters

BETS-4
Issue 1
November 1st, 1996
Revised: May 2023

Purpose

This document contains the technical standards and requirements for the issuance of a Technical Acceptance Certificate (TAC) for television broadcasting transmitters.

A certificate issued for equipment classified as type approved or as technically acceptable before the coming into force of these technical standards and requirements is considered to be a valid and subsisting TAC.

A Technical Acceptance Certificate is not required for equipment manufactured or imported solely for re-export, prototyping, demonstration, exhibition or testing purposes.

Preface

Broadcasting Equipment Technical Standard BETS-4, issue 1, Technical Standards and Requirements for Television Broadcasting Transmitters, was issued November 1, 1996. This revision of  BETS-4 Issue 1 incorporates editorial and formatting changes to meet the Canada accessibility requirements. No modifications or changes in the content of BETS-4, issue 1, have been made.

Inquiries may be submitted by one of the following methods:

By mail to the following address:

Innovation, Science and Economic Development Canada
Engineering, Planning and Standards Branch
Attention: Regulatory Standards Directorate
235 Queen Street
Ottawa ON  K1A 0H5
Canada

By email to spectrumengineering-genieduspectre@ised-isde.gc.ca.

ISED publications related to spectrum management and telecommunications are available on the Spectrum Management and Telecommunications website.

Issued under the authority of
the Minister of Innovation, Science and Industry

____________________________________
Martin Proulx
Director General
Engineering, Planning and Standards Branch

Contents

1. General

This section sets out the general requirements and references related to this TV broadcasting transmitters standards.

The standards and requirements in this document are the pre-requisite conditions for the issuance of a Technical Acceptance Certificate (TAC) for television broadcasting transmitters.

Those seeking to obtain a TAC for television transmitters shall, at their own expense, carry out the required tests and send to the Innovation, Science and Economic Development Canada (ISED) a certification submission and an engineering brief prepared in accordance with Certification of Radio Apparatus and Broadcasting Equipment (RSP-100).

The engineering brief, signed by a professional engineer licensed by a provincial association, shall demonstrate that the equipment meets the technical standards in this document.

Notwithstanding the fact that a radio apparatus meets all applicable requirements, ISED reserves the right to require that adjustments be made to the equipment should it cause interference.

Any major design or component changes, other than the replacement of defective components by equivalent parts, will void the approval unless notified to and approved by ISED.

2. Testing and labelling

This section provides an overview of the content of this document. It also specifies the classification or categories of low power TV broadcasting transmitting equipment and the requirements to be followed for proper labels identification.

Section 3 to 6 contain the general equipment standards and the minimum emission standards which relate to the radiated signal of the TV transmitting equipment. Compliance to the standards of these sections shall be supported by an engineering brief stating measurement results in accordance with Certification of Radio Apparatus and Broadcasting Equipment (RSP-100).

Annex A contains the performance standards recognized by the industry to ensure quality operation of TV broadcasting equipment. Compliance to the standards of Annex A shall be supported by a statement certifying that the equipment meets the standards. The submission of test results for performance measurements is not required but the results shall be kept on file by the applicant.

This document covers the transmitting equipment proper: namely from the video and audio input terminals or the RF input terminal to the output terminals including the filters and the diplexer supplied with the transmitting equipment.

Equipment considered as low power TV broadcasting transmitting units is classified under one of the following categories:

Category A: Low power equipment designed to operate in a varying temperature environment.

Category B: Low power equipment designed to operate in a controlled temperature environment.

In the event that the equipment fails to function during the certification tests, all tests affected by the failure shall be repeated after the fault has been corrected.

The transmitting equipment shall be capable of meeting the standards in this document on each channel at the rated power output for which it is designed to operate (see also 6.1.4.).

Each certified broadcasting equipment must display in a conspicuous location:

  • the manufacturer's name, trade or brand name (if different from the manufacturer's name)
  • the model identification
  • the serial number
  • the Technical Acceptance Certificate number
  • the certificate number for low power equipment shall be suffixed with the appropriate category designator (see 2.4).
  • the name of the certification assignee

The identification label must be indelible, tamper-resistant and affixed permanently or stamped in such a manner as not to be removable except by destruction or defacing.

3. Standard test conditions

This section relates to the general conditions to be applied to a TV transmitting equipment for compliance testing. It includes, from Sub-section 3.1 to Sub-section 3.9, a set of fixed conditions or standards to be used so the transmitting equipment can be accurately tested to ensure that no appreciable error is introduced in the results.

3.1 Definition

Standard test conditions are those conditions which shall apply to a transmitting equipment while it is being tested for minimum requirements. These conditions apply unless otherwise specified. Where no special conditions are called for in the tests, the conditions shall be those specified by the manufacturer for normal operation, and these shall be stated in the engineering brief.

3.2 Standard test voltage

Shall be one of the rated power supply voltages specified by the manufacturer.

3.3 Standard temperature

Shall be no less than 20ºC. Actual temperature shall be recorded in the engineering brief.

3.4 Standard test load

Shall consist of an impedance of substantially zero reactance and a resistance equal to the surge impedance of the load into which the equipment is designed to operate. The test load impedance shall be essentially constant over the band of frequencies being considered with a return loss of 32 dB minimum, 1.05:1 or better voltage standing wave ratio (VSWR) over the operating channel.

3.5 Standard test frequency

Shall be the visual and aural carrier frequencies of the channel for which the equipment is designed to operate. For equipment capable of operating on one of several channels, tests shall be made on one channel in each band.

3.6 Standard test input signals

  • The standard video test input signal shall be in accordance with the standard television signal as specified for system M/NTSC (see Appendix A), and shall have a peak-to-peak amplitude of 1.0 volt, (140 IRE units). The polarity of the signal shall be black negative. The voltage shall be measured across the input terminals.
  • The standard aural test signal shall be a 400 Hz sine wave.
  • The standard RF test signal shall be the standard television signal as specified for system N/NTSC (see Appendix A). The RF input signal for the translator shall be derived from a test modulator and shall occupy a band of spectrum which coincides with a standard designated television channel. The signal shall contain simultaneously a visual carrier modulated with a video waveform consisting of sync, blanking and picture signal as appropriate for the test and an unmodulated aural carrier at a level 10 dB below the peak visual carrier. Unless otherwise specified, the level of the RF input signal shall be 1 mVrms (0 dBmV).

3.7 Standard test equipment

All measurements shall be made with test instruments of accuracy sufficient to ensure that no appreciable error due to test equipment is introduced in the results.

3.8 Standard test set-up

3.8.1 Internally diplexed transmitting equipment

Unless stated otherwise, all visual tests shall be made with the unmodulated aural carrier present at rated power output and all aural tests shall be made with a visual carrier present, at the rated power output and modulated with a staircase video waveform of 50% average picture level (APL). For tests requiring a demodulated video output, a test demodulator with appropriate display devices or metres shall be used.

3.8.2 Externally diplexed transmitting equipment

The standard test load shall be connected to the output of the diplexer and tests carried out with one transmitter on at a time. For tests requiring a demodulated output the same monitoring equipment shall be used as for internally diplexed equipment.

Unless otherwise stated, all tests shall be performed with the harmonic filters and the external diplexer connected between the transmitters and the sampling point for the test concerned.

3.8.3 Translating equipment

The standard test load shall be connected to the output of the translator (see definition in 4.1) and tests carried out with the test signal supplied from the test modulator unless specified otherwise. For tests requiring an demodulated output, the same monitoring equipment shall be used as for internally diplexed equipment.

3.9 Warm-up Time

The transmitting equipment and test equipment shall be switched on at least 30 minutes before any test is started.

4. Transmitting equipment standards

This section provides the definitions for TV transmitter, TV translator and lower transmitting equipment. It also includes the technical requirements to be met for these television broadcasting transmitters.

4.1 Definitions

Transmission system: A television transmitting system consists of the apparatus necessary to convert the input signals to standard output signals as specified in television system M/NTSC (see Appendix A).

Transmitter: A television transmitter consists of the apparatus necessary to convert the standard video and audio input test signals to the standard television output signal as specified for television system M/NTSC (see Appendix A).

Translator: A television translator consists of the apparatus necessary to convert a standard RF television input signal to the standard television output signal as specified for television system M/NTSC (see Appendix A).

Low power transmitting equipment: A television transmitter or translator having a maximum power output of 50 watts on VHF channels and 500 watts on UHF channels, and is designed to be operated under the requirements for low power television broadcasting stations under one of the following categories of operating conditions:

Category A: Equipment designed to operate in a varying temperature environment.

Category B: Equipment designed to operate in a controlled temperature environment.
The appropriate category designation will be suffixed to the certificate number.

4.2 Type of emission

Visual transmission shall employ vestigial sideband amplitude modulation and aural transmission shall employ frequency modulation.

4.3 Power output rating

The power output rating of a television transmitting equipment is that of the visual transmission section.

4.4 Audio pre-emphasis

The audio signal shall be pre-emphasized in accordance with a 75 µs pre-emphasis curve (see Appendix B).

4.5 Power supply rating

The preferred AC voltage input ratings are 120/240 V single phase, 120/208 V three phase, or 480 V three-phase, at a frequency of 60 Hz. Voltage, frequency, maximum kVA rating, and power factor shall be indicated on the equipment.

4.6 Phase-to-phase loading

The equipment, if rated above 10 kVA input, shall present a balanced load to the AC mains such that the current in each phase shall be balanced within 10% of the average of the three currents.

5. Equipment requirements

This section specifies the equipment requirements to be met in order to obtain a Technical Acceptance Certificate.

5.1 Design

Transmitting equipment shall be designed according to good engineering practice.

5.2 Protection of personnel

The equipment shall be so constructed that all hazardous components are totally enclosed, or protected from accidental contact by personnel. The equipment enclosure shall be sufficient to provide adequate personnel safety during operation.

5.3 Labelling

The equipment should be labelled according to the requirements in 2.7.

5.4 Equipment changes and modifications

Any major design or equipment changes outside the replacement of defective components by equivalent parts made to an approved equipment will void the type-approval unless notified to and approved by ISED. The notification shall provide information demonstrating that the modification provides equal or improved equipment performance.

6. RF emission standards

This section specifies the requirements applicable to radio frequency emission subject to this standard. It includes the definitions, the methods of measurements and the limits for the following parameters: visual power output, aural power output, carrier frequency stability, intermodulation, spurious emissions, cabinet radiation and occupied bandwidth.

6.1 Visual power output rating

This section sets out the requirements applicable to visual power output subject to this standard. Its definition, method of measurement and technical requirements to be met follow.

6.1.1 Definition

The visual power output rating of a television transmitting equipment shall be the peak envelope power which is the average power during a synchronizing pulse.

6.1.2 Method of Measurement

The visual carrier shall be modulated with sync and blanking only, such that the sync amplitude at the transmitter output will be 25% of the voltage between peak of sync and zero carrier. For translating equipment, the test modulator shall be modulated as above and the RF test signal set at the manufacturers recommended input value. The output shall be connected to the standard test load. Measure the average power output. The peak envelope power is the measured average power output multiplied by a factor of 1.68.

6.1.3 Standard

  • The standard rating of power output for the visual transmission section shall be as specified by the individual manufacturer. The equipment shall be capable of being adjusted to deliver the rated visual power output when the AC input voltage is 5% above or below rated value.
  • The engineering brief shall state the power output limits over which the equipment complies with this specification.
  • Power output adjustment of the equipment shall permit operation to at least 3 dB below rated power output.

6.1.4 Standard low power

The standard rating of power output for the visual transmission section shall be as specified by the individual manufacturer but shall not exceed 50 watts on VHF channels and 500 watts on UHF channels. The equipment shall be capable of maintaining the rated visual power output within 1 dB.

6.2 Aural power output rating

This section sets out the requirements applicable to aural power output subject to this standard. Its definition, method of measurement and technical requirements to be met follow.

6.2.1 Definition

The aural carrier power output is the power of the aural transmission section available at the output terminals of the equipment when connected to the standard test load.

6.2.2 Method of measurement

The average power output of the unmodulated aural carrier shall be measured while operating into the standard test load either by using a power measuring device or by a calorimetric method.

6.2.3 Standard

  • The measured aural carrier output shall not be less than 10% nor more than 20% of the output power of the visual transmission section specified in 6.1.3.
  • Power output adjustment shall permit operation to at least 3 dB below the level determined in the paragraph above.

6.2.4 Standard low power

The measured aural carrier output shall not be less than 5% nor more than 20% of the power output of the visual transmitter.

6.3 Carrier frequency stability

This section sets out the requirements applicable to carrier frequency stability subject to this standard. Its definition, method of measurement and standard to be met follow.

6.3.1 Definition

The carrier frequency stability of the transmitting equipment is a measure of the ability of the equipment to maintain its assigned frequency.

6.3.2 Method of measurement

After a warm-up period of one hour at rated input voltage, measure the frequency of the visual and aural carriers at one minute intervals during a period of 15 minutes. From those measurements determine a mean frequency for each carrier. Then measure the operating frequency at ambient temperatures of 5 ºC and 45 ºC and at the following three values of power supply voltage for each of these temperatures; 85%, 100% and 115% of nominal supply voltage. For Category "B" low power equipment, the range of the controlled temperature environment shall be specified by the manufacturer but shall not be less than 10 ºC.

6.3.3 Standard

The frequency stability of both visual and aural carriers shall remain within ±500 Hz of the mean frequency.

6.3.4 Standard-low power

The frequency stability of both the visual and aural carriers shall remain within ±0.003% of the mean frequency. Note that the Category "B" equipment shall be operated in a controlled temperature environment.

6.4 Intermodulation

This section sets out the requirements applicable to intermodulation subject to this standard. Its definition, method of measurement and the limit value to be met follow.

6.4.1 Definition

Intermodulation (IM) products are beat signals generated by various combinations of carriers of the nature mf1 ±nf2 ±pf3 where m, n and pare integers. The visual and aural carriers and colour sub-carrier can combine to form IM products. Six predominant products, with respect to picture carrier, are at ±920 kHz, ±2.66 MHz, +5.42 MHz and +7.16 MHz.

6.4.2 Method of measurement

The reference level used as 0 dB shall correspond to the rated power output of the equipment (visual). The unit shall then be fed with a video test signal consisting of sync, blanking and a 3.58 MHz sinewave on a 50% APL pedestal. The unmodulated aural carrier shall be present. The level of these carriers shall be adjusted so that their amplitudes with respect to reference level are:

visual carrier -8 dB
3.58 MHz subcarrier -17 dB
aural carrier -10 dB*
* or 7 dB if so rated in 6.2.3

The instantaneous peak levels of the predominant IM products and the harmonic product of the chrominance carrier shall be measured on a spectrum analyser or other suitable frequency selective voltmeter.

6.4.3 Standard

The level of the predominant IM products shall be at least 53 dB below the reference level.

6.4.4 Standard-low power

The level of the predominant IM products shall be at least 50 dB below the reference level.

6.5 Spurious emissions

This section sets out the requirements applicable to spurious emissions subject to this standard. Its definition, method of measurement and the technical specifications to be met follow.

6.5.1 Definition

Spurious emissions are unwanted emissions occurring at the output terminals of the transmitting equipment, at frequencies other than those of the predominant intermodulation products described in Section 6.4.1.

6.5.2 Method of measurement

The transmitting equipment shall be operated into the standard test load at rated power. The aural carrier shall be unmodulated and the visual carrier shall be modulated with normal black level either with or without sync. Both signals shall be present for internally as well as externally diplexed transmitters. Using a sampling device, measure all spurious emissions below 1.8 GHz or up to the third harmonic of the aural carrier frequency, whichever is the higher.

The voltage of the emission shall be measured with a frequency selective instrument. The attenuation versus frequency characteristics of the power sampling device and the load used in this test shall be known over the range of frequencies involved.

Record all spurious outputs in dB relative to peak envelope power except those more than 20 dB below the values in 6.5.3.

6.5.3 Standard

Spurious emissions of the transmitting equipment shall not exceed the values given in the following table:

Transmitter power Spurious emissions Max. value
Any power -4,5 MHz and +9,0 MHz -40 dB*
Below 25 watts all others -46 dBW
Above 25 watts all other spurious including harmonics -60 dB*

* Referred to peak envelope power of the equipment

6.6 Cabinet radiation

This section sets out the requirements applicable to cabinet radiation subject to this standard. Its definition, method of measurement and the limit value to be met follow.

6.6.1 Definition

Cabinet radiation is any emission from the equipment housing or enclosure from sources other than the normal output ports.

6.6.2 Method of measurement

The visual and aural transmitters shall be operated at rated power output. A receiving dipole (or equivalent), located alternately at a known distance between three and ten metres from at least three sides of the equipment (i.e. front, back, left or right hand side), shall be connected to a calibrated field strength metre or frequency selective voltmeter. Field strength measurements shall be made of all emissions (including the fundamental and harmonics of the visual and aural carrier frequencies) up to 1.8 GHz or the third harmonic of the aural carrier frequency, whichever is the higher frequency. For the measurement, the receiving antenna shall be rotated in all three planes and the maximum received field shall be noted (allowance shall be made for antenna factor and transmission line loss of the measuring equipment). Using the free space formula below, calculate the reference field strength:

\(E = 7 \sqrt{P}/r \) volts per metre

where P is the rated visual output power in watts and r is the distance in metres.

6.6.3 Standard

Emissions at any frequency shall be at least 54 dB below the calculated field strength reference level with the exception that, for UHF equipment at the fundamental frequency, emissions shall be at least 48 dB below the reference level. Any radiation weaker than 70 dB below the reference level need not be recorded.

6.7 Occupied Bandwidth

This section sets out the requirements applicable to occupied bandwidth subject to this standard. Its definition, method of measurement and standard to be met follow.

6.7.1 Definition

The occupied bandwidth is the frequency bandwidth within which the mean power of the radiated emission is confined in accordance with specified limits.

6.7.2 Occupied video bandwidth

The visual occupied bandwidth is the amplitude versus frequency characteristic of the visual transmitter including in-band and upper and lower sideband attenuation.

6.7.3 Method of measurement

For this test the aural carrier shall be turned off and the equipment shall be operated at rated power output with video input consisting of sync, blanking, and a variable pedestal on which is superimposed a 10 MHz video sweep signal of 20 IRE units. Initially set the pedestal to 50 IRE units. Sample the equipment output and feed it to a tracking receiver (sideband analyser or spectrum analyser).

Display the frequency range from visual carrier -7.25 MHz to visual carrier +7.75 MHz on the oscilloscope. Set the 0 dB reference to the output level at visual carrier + 200 kHz. Measure the output with the pedestal set to 50 units and then change the pedestal to 20 and 80 IRE units and record the results.

6.7.4 Standard

The amplitude versus frequency characteristic between visual carrier -7.25 MHz and +7.75 MHz shall be within the limits shown in Figure 1. In addition, with the variable pedestal changed to 20 IRE units and 80 IRE units, the response shall not vary from that at 50 IRE units by more than ±0.75 dB.

The response at visual carrier +4.18 MHz shall not be attenuated by more than the following, (see inset, Figure 1):

  • for internally diplexed equipment: -1.5 dB
  • for externally diplexed equipment not provided with a diplexer: -1.5 dB
  • for externally diplexed equipment which include a diplexer: - 3.0 dB

6.7.5 Aural occupied bandwidth

6.7.6 Definition

The occupied bandwidth is the frequency bandwidth such that below its lower and above its upper frequency limits, the mean powers radiated are each equal to 0.5% of the total mean power radiated by a given emission.

6.7.7 Method of measurement

Test signals applied to the equipment input shall be representative of the system employed and shall result in 85% of the maximum specified aural carrier deviation.

6.7.8 Monaural transmitter

The aural transmitter shall be modulated with a 15 kHz tone at 85% (+21.25 kHz). A spectrum analyser shall be connected to the output of the aural transmitter and the energy at 120 kHz above and below the aural carrier shall be measured and referenced to the unmodulated carrier.

6.7.9 M.T.S. stereo transmitter

The composite input on the aural transmitter shall be modulated by a 15 kHz L+R at ±15.25 kHz deviation and a 15 kHz L-R at ±30.5 kHz deviation, a pilot carrier at ±5 kHz deviation, a 78.6 kHz carrier deviated ±10 kHz, and a 102.3 kHz carrier deviated ±3 kHz so that total deviation is ±63.75 kHz. A spectrum analyser shall be connected to the output of the aural transmitter and the energy at 120 kHz above and below the aural carrier shall be measured and referenced to the unmodulated carrier.

6.7.10 Other multichannel transmitter

The aural transmitter input shall be modulated so as to be representative of the system employed to produce ±63.75 kHz deviation. A spectrum analyser shall be connected to the output of the aural transmitter and the energy at 120 kHz above and below the aural carrier shall be measured and referenced to the unmodulated carrier.

6.7.11 Standard

The energy above or below the ±120 kHz band may not exceed 0.5% of the total mean power within the band.

6.7.12 Translator occupied bandwidth

6.7.13 Definition

The occupied bandwidth of translators is the frequency bandwidth given by the amplitude/frequency characteristic measured at the output of the unit.

6.7.14 Method of measurement

With the AGC inoperative, the unit shall be fed with a sine wave input at the standard level and the frequency of the video carrier of the input channel. The unit shall then be set to deliver rated power output into the dummy load. This output shall be deemed the reference. With the amplitude constant, sweep the frequency of the sine wave between ±8 MHz of the visual carrier at three levels of input 0 dBmV, -16 dBmV and +16 dBmV.

6.7.15 Standard

The occupied bandwidth given by the amplitude versus frequency response of the unit with 0 dBmV input shall be within the limits shown in Figure 2. The amplitude versus frequency response of the unit at ±16 dBmV shall not vary by more than ±l dB from the response at 0 dBmV.

Figure 1: Amplitude vs frequency characteristic

Description of Figure 1

The figure is a plot illustrating amplitude versus frequency characteristics. The relative amplitude is plotted on the y axis versus the frequency relative to visual carrier on the x axis. The axis limits are 5 to 50 dB and -8 to + 8 MHz, respectively. Two curves illustrating visual carriers as -7.25 MHz and +7.75 MHz are shown. Sidebands attenuations are included. An insert showing the response at the visual carrier +4.18 MHz and its attenuation specification for internally and externally diplexed equipment is given.

 

Figure 2: Amplitude vs frequency response translators

Description of Figure 2

The figure is a plot illustrating amplitude versus frequency response translators. The relative amplitude in dB units is plotted on the y axis versus the frequency relative to visual carrier in MHz on the x axis. The axis limits are -30 to +10 dB and -3 to +7 MHz, respectively. There are two indicators on the x axis showing the visual carrier point and the aural carrier at 0 MHz and 4.5 MHz, respectively. There are two data lines on the x axis: one from −3 to + 4.75 MHz and another from −0.75 to +7 MHz. These lines intersect at the visual carrier point (0 dB, 0 MHz). The data lines illustrate the following:

  • First data line: the relative amplitude between -3 and -2.5 MHz is -20 dB; between -2.5 MHz to the -0.15 MHz of the visual carrier is approximately 0.5 dB, dropping to -1 dB at +0.15 MHz from the visual carrier, and remaining at -1 dB from here to +4.75 MHz from the visual carrier. The line drops to -30 dB at +4.75 MHz.
  • Second data line: the relative amplitude rises from less than -30 dB to -1 dB at -0.75 MHz, rises to +0.5 dB from -0.15 MHz to +0.15 MHz, remains at +0.5 dB from here to +6 MHz, then drops to -20 dB until +7 MHz.
 

Annex A: Technical standards

A1. Visual performance standards

This section contains the visual performance standards to ensure quality operation of TV broadcasting equipment. Definitions, method of measurements and technical specifications related to these parameters are given in sub-sections A1.1 to A1.11, when applicable.

A1.1 Visual transmitters

A1.1.1 Definition

The visual transmitter shall be that equipment required to convert the standard composite colour video signal (see Figure A1) to a modulated radio frequency signal delivered to the output transmission line.

A1.2 Transmitter input

This section sets out the requirements applicable to transmitter input subject to this standard. Its definition, method of measurement and standard to be met follow.

A1.2.1 Definition

The transmitter input is that terminal point that accepts the video signal that will modulate the visual carrier in compliance with this specification and shall be labelled "Video Input".

A1.2.2 Impedance and return loss

A1.2.2.1 Definition

The input impedance is the impedance presented by the transmitter at its video input terminal. The return loss is the measure of dissimilarity between the input impedance and the standard impedance of the transmitter.

A1.2.2.2 Method of measurement

The input impedance and return loss may be measured with impedance measuring equipment having an error no greater than ±1.0%.

A1.2.2.3 Standard

The standard impedance shall be 75 Ω unbalanced. The input shall exhibit a return loss of at least 32 dB over the frequency range from 0.0 to 4.2 MHz.

A1.2.3 Input signal level for rated modulation

A1.2.3.1 Definition

The input signal level for rated modulation is that composite video signal amplitude which will drive the transmitter input so as to produce a modulated RF output signal meeting this specification.

A1.2.3.2 Method of measurement

The input voltage shall be measured by means of a properly calibrated oscilloscope or television waveform monitor, having known deflection sensitivity and at least 4.5 MHz bandwidth, connected across the transmitter input terminals. The transmitter shall be adjusted for proper modulation at rated peak power into a standard test load. The input voltage shall be determined by measuring the peak-to-peak deflection on the display.

A1.2.3.3 Standard

The amplitude of the composite video signal applied to the input terminal shall nominally be 1.0 volt peak-to-peak when the signal contains reference white.

A1.3 Modulation

This section sets out the requirements applicable to modulation subject to this standard. Its definition, method of measurement and standard to be met follow.

A1.3.1 Definitions

Maximum carrier level, blanking level, and reference white level are as defined for system M/NTSC (see Appendix A).

A1.3.2 Modulation capability - Method of measurement

Using the standard test set-up, operate the transmitter at rated output with a standard staircase video input at 50% APL (see Figure A2). Set the oscilloscope for 100% at maximum carrier level and zero at zero carrier level.

A1.3.3 Standard

With the blanking level at 75%, the maximum carrier level shall remain between 98% and 102% of the original, and the reference white level shall be at 12.5% ±2.5%.

A1.3.4 Modulation stability - Method of measurement

With operation as in 1.3.2, vary the staircase APL to 10% and to 90%.

A1.3.5 Standard

At APL between 10% and 90%, the maximum carrier level shall not vary by more than 3% and the blanking level by more than 1.5% of maximum carrier level.

A1.3.6 Field time distortion - Method of measurement

Retaining the set-up in 1.2.2 replace the staircase input signal with a window signal. View the oscilloscope at field rate with DC restoration disabled.

A1.3.7 Standard

The tilt on the window signal shall not exceed 2% of the overall window amplitude between blanking and reference white level.

A1.4 Signal to noise ratio

This section specifies the requirements applicable to signal to noise ratio subject to this standard. Applicable definitions, method of measurements and the limit values to be met follow.

A1.4.1 Signal to random noise ratio (10 kHz to 4.2 MHz - Unweighted)

A1.4.1.1 Definition

The signal to unweighted random noise ratio of the transmitter is the ratio, stated in decibels, of the peak-to-peak amplitude of the video modulation from blanking to reference white to the RMS amplitude of noise modulation measured at the output of the standard demodulator.

A1.4.1.2 Method of measurement

The signal to unweighted random noise measurement shall be made using either a waveform monitor or a video noise metre. Connect the signal through the low and high pass filters to confine the noise to the video passband (see Figures A3(a) and A3(b)). The measurement shall be made on a flat field test signal at 10 IRE units.

A1.4.1.3 Standard-transmitters
The signal to unweighted random noise ratio shall be 50 dB or greater.

A1.4.1.4 Standard-translators

The signal to unweighted random noise ratio for a 0 dBmV RF input level shall be 46 dB or greater for translators operating with input on channels 2 - 13 and 44 dB or greater for translators operating with input on channels 14 - 69.

A1.4.2 Signal to low frequency noise ratio (30 Hz - 15 kHz - Unweighted)

A1.4.2.1 Definition

The signal to low frequency noise ratio is defined in two ways:

  1. Signal to RMS noise or
  2. Signal to peak-to-peak noise relative to reference modulation

Each ratio, expressed in decibels, is the ratio of the modulation level which would be produced by 100% modulation of the transmitter with a single frequency sine wave to the noise. 100% modulation is defined as modulation from zero carrier output to peak synchronizing level.

A1.4.2.2 Method of measurement

The signal to low frequency noise shall be measured at the output of the standard demodulator using a waveform monitor or a video noise metre. The output of the demodulator shall be filtered by a 30 Hz high-pass filter and a 15 kHz low-pass filter.

A1.4.2.3 Standard

The signal to low frequency noise ratio within a band of 30 Hz to 15 kHz shall be at least 52 dB RMS and 40 dB peak-to-peak.

Note: The reference modulation level for expressing the signal to random noise level modulation from carrier blanking to carrier reference white is different from the reference level used for low frequency noise, 100% modulation. The following relationship exists between the noise ratios so referenced:

Signal (100 IRE) to Noise (dB) + 4.1 dB = Signal (100% modulation) to Noise (dB).

A1.5 Luminance non-linearity

This section specifies the requirements applicable to luminance non-linearity subject to this standard. Its definition, method of measurement and the limit value to be met follow.

A1.5.1 Definition

Luminance non-linearity is a measure of the gain variation of the system for a luminance signal as a function of instantaneous luminance level and APL.

A1.5.2 Method of measurement

The transmitter input terminal shall be fed a staircase test signal of 50% APL (see Figure A2). Using the standard demodulator and a waveform monitor, sample the visual transmitter output. Employ the low pass filter section of the waveform monitor to differentiate the stairsteps. Comparing the amplitudes of the pulses, the pulse with the greatest amplitude is set to 100 IRE. The pulse with the smallest amplitude is read as a percentage of the greatest.

The above measurement shall be repeated using 10% APL and 90% APL (see Figure A2).

A1.5.3 Standard

The luminance non-linearity shall not be greater than 10% for APLs between 10% and 90%. For klystron transmitters using a modulating anode pulser, the non-linearity shall not be greater than 15%.

A1.5.4 Standard-low power

The luminance non-linearity shall not be greater than 20% for APLs between 10% and 90% and luminance levels between blanking and reference white.

A1.6 Differential gain distortion

This section specifies the requirements applicable to differential gain distortion. Its definition, method of measurement and the limit value to be met follow.

A1.6.1 Definition

Differential gain distortion is the change in gain of the system for a small high frequency sine wave (chrominance) signal at two levels of low frequency (luminance) signal upon which it is superimposed.

A1.6.2 Method of measurement

The transmitter shall be fed a standard staircase signal with 3.58 MHz colour subcarrier
(see Figure A2(b)). Using a linear demodulator (or a demodulator of known characteristics, and applying appropriate correction factors), the output is sampled and detected and the visual portion passed through a high pass filter to an oscilloscope, or any other suitable means of observing the 3.58 MHz component of the test signal. Any deviation from a constant amplitude display of the 3.58 MHz signal, when viewed at the line rate frequency, is the differential gain variation. The differential gain is the difference between the maximum and minimum 3.58 MHz signal amplitude divided by the maximum amplitude. Observe differential gain at 10%, 50% and 90% APL.

A1.6.3 Standard

The differential gain shall not be greater than 7%.

A1.6.4 Standard-low power

The differential gain shall not be greater than 15%.

A1.7 Differential phase distortion

This section sets out the requirements applicable to differential phase distortion. Its definition, method of measurement and the limit value to be met follow.

A1.7.1 Definition

Differential phase distortion is the change in phase through the system for a small high frequency sine wave (chrominance) signal at two levels of a low frequency (luminance) signal upon which it is superimposed.

A1.7.2 Method of measurement

Using the same set-up as for differential gain and with the same input signal, the output is sampled and detected and passed to any suitable phase measuring equipment. Measurements shall be made at 10%, 50% and 90% APL.

A1.7.3 Standard

The differential phase shall be within ±4 of the colour burst and the overall difference shall not exceed 5° .

A1.7.4 Standard-low power

The differential phase shall be within ±7 of the colour burst and the overall difference shall not exceed 10°.

A1.8 Incidental carrier phase modulation

This section sets out the requirements applicable to incidental carrier phase modulation. Its definition, method of measurement and the limit value to be met follow.

A1.8.1 Definition

Incidental carrier phase modulation (ICPM) is extraneous phase modulation created in the process of visual modulation and amplification (AM to PM conversion).

A1.8.2 Method of measurement

The transmitter input terminal shall be fed a staircase test signal (see Figure A2). A sample of the transmitter output signal shall be detected in the standard demodulator with the sound notch filter out. Synchronous detection referenced to an unmodulated carrier, phase referenced to blanking, shall be employed.

The quadrature component of synchronous detection is used to display the luminance incidental carrier phase characteristic on the waveform monitor.

A1.8.3 Standard

Incidental carrier phase modulation by the luminance signal and composite sync shall not exceed ±2 referenced to blanking level.

A1.9 Group delay response

This section sets out the requirements applicable to group delay response. Its definition, method of measurement and the limit value to be met follow.

A1.9.1 Definition

The group delay response versus frequency of a transmitter is the variation with modulation frequency of the group delay.

A1.9.2 Method of measurement

The measurement shall be made with the transmitter operating into the standard test load. The measurement shall be made either on the transmitter output signal detected by the standard demodulator, or on the separate sideband signals as detected on a synchronous sweep receiver. The group delay measurement equipment is used under the same operating conditions as in paragraph 6.7, except that the maximum excursion of the modulating signal shall not exceed 25 IRE units. Composite video signals may be used if they are without a vertical interval since it obscures the measurement on some types of delay measuring equipment.

A1.9.3.1 Standard

A sine wave introduced at the input shall produce an RF signal having a group delay relative to 200 kHz of zero ns up to a frequency of 3.0 MHz and then linearly decreasing to 4.18 MHz intercepting -170 ns at 3.58 MHz.

The tolerance shall increase linearly from 25 ns at 3.58 MHz to ±50 ns at 2.0 MHz where the tolerance remains constant down to 0.2 kHz and the tolerance shall increase linearly to ±50 ns at 4.18 MHz from that at 3.58 MHz (see Figure A4)

High rate group delay ripples as a result of saw filter triple transit effect are excluded.

A1.9.3.2 Standard - Translators

The group delay shall be within ±40 ns of the reference delay characteristic of the test modulator.

A1.9.3.3 Standard-low power

The delay characteristic shall be the same as specified in 1.9.3.1 except the permitted tolerance shall be twice that specified in 1.9.3.1.

A1.10 Linear waveform distortion

This section specifies the requirements applicable to lineal wave distortion. Definitions, method of measurements and the limit values to be met are given.

A1.10.1 Definition

Linear waveform distortion is a measure of the transmitter's ability to faithfully reproduce step functions or pulses. One method of measure is the K factor which describes the transmitter's ability to reproduce the 2T pulse and bar measurement signal.

A1.10.2 K pulse to bar (Kpb) rating

A1.10.2.1 Definition

The K pulse to bar rating is a measurement of the peak amplitude of the 2T pulse relative to the amplitude of the mid point of the associated luminance bar waveform. It is expressed as the K pulse to bar rating in percent and is measured with a standard NTSC type A graticule (see Figure A5(b)).

A1.10.2.2 Method of measurement

Apply a full field composite test signal (Figure A5(a) to the video input of the transmitter under test and connect the demodulated video output (using synchronous detection) to a calibrated waveform monitor, equipped with graticule "A". Centre the 2T pulse peak on the Kpb scale. The vertical gain is adjusted to put the bar centre point at 100 IRE and the blanking level at 0 IRE. The K pulse to bar rating is then measured on the graticule using the "Kpb" lines at the top centre of the graticule. To extend the range of the measurement, set the vertical sensitivity of the waveform monitor so that the centre point of the bar waveform has an amplitude of 100 IRE.

Measure the peak amplitude of the 2T pulse and read the K pulse to bar rating from the nomogram shown on Figure A5(c). If the 2T pulse is greater than 120 IRE in amplitude, move the display down to put the blanking level at -40 IRE, to keep the 2T pulse "on scale".

A1.10.2.3 Standard

The K pulse to bar rating (Kpb) shall not exceed 2.5%.

A1.10.3 2T pulse k rating (K2T)

A1.10.3.1 Definition

The K rating of the 2T pulse (K2T) is a time weighted measurement of the subjective impairments caused by close-in echoes on the TV signal and is measured with the standard NTSC type B graticule (See Figure A5(d)) and expressed in percentage K.

A1.10.3.2 Method of measurement

Apply a full field composite test signal ((Figure A5(a)) to the video input of the transmitter under test and connect the demodulated video output (using synchronous detection) to a calibrated waveform monitor. To use "Graticule B" to measure K2T, adjust the waveform monitor sweep rate to 0.2 µs/div (or x25 magnifier with a 5 µs/div DISPLAY rate) and use the variable vertical sensitivity to adjust the pulse height to 100 IRE. The lobe that most closely approaches the dotted K2T = 5% outline defines the K2T rating for the transmitter under test. For small values of K2T the vertical sensitivity of the monitor may be increased by a factor of 2 to increase the resolution of the measurement. In this case, the dotted outline becomes K2T = 2.5%. The K2T rating is estimated by subdividing an imaginary vertical line through the lobe peak into convenient units, and expressing the lobe amplitude as a fraction of the distance between the blanking level reference line and the dotted K2T line.

A1.10.3.3 Standard

The 2T pulse K rating shall not exceed 2.5% K.

A1.11 Chrominance-luminance relative amplitude and delay

This section sets out the requirements applicable to chrominance/luminance relative amplitude and delay. Its definition, method of measurement and the limit value to be met are given.

A1.11.1 Definition

The chrominance-luminance relative amplitude and delay is the relative change in the amplitude and timing of the chrominance and luminance components of a television signal from the output of the transmitter.

A1.11.2 Method of measurement

Feed the transmitter input with the composite test video signal (see Figure A5(a))

Using the standard demodulator in the synchronous detection mode with the sound notch filter out, the test signal bar shall modulate the transmitter to reference white while maintaining rated blanking and peak output power levels.

The relative delay change is determined after adjustment of the 12.5T modulated pulse to 100 IRE units by noting the displacement of the baseline by amplitudes Yl and Y2 and referring to the nomograph of Figure A6 or by using the formula:

Chrominance-luminance delay = 20(Yl.Y2)½ ns

Alternately, chrominance amplitude and delay adjustments may be added to the video signal to attain a 12.5T pulse without baseline displacements, recording the magnitude of the corrections required. The magnitudes of the required corrections are equal to the transmitter chrominance-luminance amplitude and delay errors.

A1.11.3 Standard

The chrominance-luminance relative amplitude shall be less than ±3 IRE units. The chrominance luminance relative delay shall be less than 50 ns.

A2. Aural performance standards

This section contains the aural performance standards to ensure quality operation of TV broadcasting equipment. Definitions, method of measurements and technical specifications related to this parameter are given in sub-sections A2.1 to A2.7.

A2.1 Aural transmitter

A2.1.1 Definition

The aural transmitter shall be that equipment required to convert monaural audio, multichannel baseband (including stereo and other subcarriers), and non-program related subcarriers, to a frequency modulated output signal.

A2.2 Transmitter input

This section sets out the requirements applicable to transmitter input. Its definition, method of measurement and the limit value to be met are given.

A2.2.1 Definition

The transmitter input terminals shall be identified as "AUDIO", "COMPOSITE" and "SUBCARRIER". Simultaneous transmitter modulation with both the AUDIO and SUBCARRIER, or alternately COMPOSITE and SUBCARRIER inputs shall be provided.

A2.2.1.1 Audio

The audio input terminals are those terminals to which signals in the range of 30 Hz to 15 kHz are connected to cause frequency modulation of the aural carrier.

A2.2.1.2 Composite

The composite input terminals are those terminals to which signals in the range of 30 Hz to 120 kHz, including BTSC baseband signals as defined in BS 15, are connected to cause frequency modulation of the aural carrier.

A2.2.1.3 Subcarrier

The subcarrier input terminals are those terminals to which signals in the range of 16 kHz to 120 kHz are connected to cause frequency modulation of the aural carrier.

A2.2.2 Input impedance

A2.2.2.1 Definition

The input impedance is the load presented to circuits supplying signals over the frequency band specified for those terminals.

A2.2.2.2 Method of measurement

The input impedance shall be measured with a suitably calibrated impedance bridge or network analyser.

A2.2.2.3 Standard

For audio inputs, the input impedance over the range of frequencies from 30 Hz to 15 kHz shall not be less than 10,000 Ω balanced with substantially zero reactance. Provision shall be made to permit the internal connection of a resistor across the input terminals to present a lower input impedance if needed.

As an example, the audio impedance may be 600/150 Ω balanced.

For composite inputs, the impedance over the range of frequencies from 30 Hz to 120 kHz shall be 75 Ω unbalanced with a return loss of at least 40 dB from 50 Hz to 50 kHz and at least 35 dB from 30 Hz to 120 kHz.

For subcarrier inputs, the input impedance over the range of frequencies from 16 kHz to 120 kHz shall be 75 Ω unbalanced with a return loss of at least 35 dB.

A2.2.3 Audio input level

A2.2.3.1 Definition

The audio input level is the level of the 400 Hz test signal at the audio input terminals necessary for ±25 kHz deviation of the aural carrier.

A2.2.3.2 Method of measurement

Suitable instruments for measuring aural carrier frequency deviation and audio input signal level shall be used. The measurement requires:

  1. An AM/FM modulation monitor with an amplitude response of ±0.05 dB over the desired frequency range, to be connected to an RF monitoring connection in the aural transmitter output transmission line.
  2. An AC signal level metre with a frequency response accuracy of ±0.02 dB to measure the voltage applied to the input terminals.

A2.2.3.3 Standard

The standard sine wave audio input level for ±25 kHz deviation at 400 Hz shall be 2.45 volts RMS corresponding to +10 dBm across a 600 Ω impedance. The transmitter shall be capable of adjustment to ±25 kHz deviation at 400 Hz at an input level of 0.775 volt RMS corresponding to 0 dBm across a 600 Ω impedance.

A2.2.4 Composite input level

A2.2.4.1 Definition

The composite input level is the level of a 20 kHz test signal at the composite input terminals necessary for ±75 kHz deviation of the aural carrier.

A2.2.4.2 Method of measurement

Suitable instruments for measuring aural carrier frequency deviation and audio input signal level shall be used. The measurement requires:

  1. An AM/FM modulation monitor with an amplitude response of ±.05 dB over the desired frequency range, to be connected to an RF monitoring connection in the aural transmitter output transmission line.
  2. An AC signal level metre with a frequency response accuracy of ±0.02 dB to measure the voltage applied to the input terminals.

A2.2.4.3 Standard

The nominal input level for ±75 kHz deviation shall be 20 kHz sine wave at 1.0 volt RMS at the 75 Ω input impedance. The transmitter shall be capable of adjustment to ±75 kHz deviation with input level of 0.5 volt RMS.

A2.2.5 Subcarrier input level

A2.2.5.1 Definition

The subcarrier input level is the level of a 20 kHz test signal at the subcarrier input terminals necessary for ±15 kHz deviation of the aural carrier.

A2.2.5.2 Method of measurement

Suitable instruments for measuring aural carrier frequency deviation and audio input signal level shall be used. The measurement requires:

  1. An AM/FM modulation monitor with an amplitude response of ±0.05 dB over the desired frequency range, to be connected to an RF monitoring connection in the aural transmitter output transmission line,
  2. An AC signal level metre with a frequency response accuracy of ±0.02 dB to measure the voltage applied to the input terminals.

A2.2.5.3 Standard

The nominal input level for ±15 kHz deviation shall be 20 kHz sine wave at 1.0 volt RMS across a 75 Ω input impedance. The transmitter shall be capable of adjustment to ±15 kHz deviation with an input level of 0.5 volt RMS.

A2.3 Modulating frequency amplitude response

This section sets out the requirements applicable to modulating frequency amplitude response. Its definition, method of measurement and the limit value to be met follow.

A2.3.1 Definition

The modulating frequency amplitude response is the ratio of input voltages expressed in dB required to obtain a constant frequency deviation over a specified range of input frequencies.

A2.3.2 Method of measurement

The measurement requires equipment with accuracy as specified in paragraph 2.2.3.2.

The transmitter is modulated with signals of frequencies in the range of interest. The carrier frequency deviation as read on the modulation monitor is kept constant and the input level is recorded of each modulating frequency.

A2.3.3 Standard

A2.3.3.1 Audio

The maximum departure of the amplitude response from the standard 75 µs pre-emphasis curve over the range of 30 Hz to 15 kHz shall not exceed ±0.5 dB up to ±25 kHz deviation.

A2.3.3.2 Composite

The maximum departure of the amplitude response from 30 Hz to 120 kHz shall not exceed ±l dB with a deviation of ±15 kHz, except in the frequency range of 50 Hz to 50 kHz where the amplitude response shall not exceed ±0.1 dB with a deviation of ±50 kHz.

A2.3.3.3 Subcarrier

The maximum departure of the amplitude response from 16 kHz to 120 kHz shall not exceed ±1 dB with a deviation of ±15 kHz.

A2.4 Modulating frequency phase response

This section sets out the requirements applicable to modulating frequency phase response. Its definition, method of measurement and the limit value to be met are given.

A2.4.1 Definition

The modulating frequency phase response is the phase shift of the demodulated signal as referenced to the signal applied to the transmitter input terminals over the specified modulating frequency range. The deviation of phase shift versus frequency from a best fit straight line is a measure of phase non-linearity.

A2.4.2 Method of measurement

The measurement requires an aural demodulator of known phase response over the desired frequency range. This demodulator is connected to an RF monitoring connection at the aural transmitter output and shall provide a demodulated output from 30 Hz to 120 kHz. The transmitter is modulated with signals at the desired frequencies. The transmitter input and demodulator output signals are compared on a suitable dual trace oscilloscope or phase difference metre while the modulating frequency is varied over the range indicated in 2.4.3.

A2.4.3 Standard

The phase shift at any frequency shall not exceed the values shown below from a best fit straight line drawn through a graph of phase shift versus frequency.

Type of input Range of frequency Maximum phase shift (degres)
Composite 50 Hz to 50 kHz (1)
30 Hz to 120 kHz (2)
±0,5
±10,0
Subcarrier 16 kHz to 120 kHz (2) ±10,0

(1)  ±50 kHz carrier deviation
(2)  ±15 kHz carrier deviation

A2.5 Frequency modulation signal to noise ratio

This section sets out the requirements applicable to frequency modulation signal to noise ratio. Its definition, method of measurement and the limit value to be met are given.

A2.5.1 Definition

Frequency modulation signal to noise ratio is the ratio in dB of a reference signal modulation level to the residual frequency modulation caused by noise and spurious components without the presence of signal modulation.

A2.5.2 Method of measurement

The measurement requires an aural demodulator. This demodulator is connected to an RF monitoring connection in the aural transmitter output transmission line. The amplitude/frequency response characteristic of the demodulator shall be within ±0.5 dB over the frequency range of interest except for audio input signals where it shall be within ±0.5 dB of the standard 75 µs de-emphasis curve. The 30 Hz to 120 kHz broadband measurement should be made with a demodulator low pass 3 dB bandwidth of approximately 150 kHz.

The transmitter is modulated to ±25 kHz deviation with the standard input signal of 400 Hz and the recovered signal from the demodulator is measured with an RMS responding device. This measurement is repeated with no modulating signal and with the input terminals shunted with a resistance equal to the source impedance of the input circuit. The ratio of the two readings expressed in dB represents the FM signal to noise ratio.

A2.5.3 Standard

A2.5.3.1 RMS noise and spurious levels referenced to ±25 kHz deviation.

30 Hz to 15 kHz          -58 dB (with 75 µs de-emphasis)*
30 Hz to 120 kHz        -30 dB or ±800 Hz deviation*

* Both conditions shall be met simultaneously.

A2.5.3.2 Discrete spurious levels referenced to ±25 kHz deviation.

30 Hz to 15 kHz          -58 dB
15 kHz to 94 kHz        -54 dB
94 kHz to 120 kHz      -48 dB

A2.6 Residual amplitude modulation

This section sets out the requirements applicable to residual amplitude modulation signal. Its definition, method of measurement and the limit value to be met follow.

A2.6.1 Amplitude modulation noise

A2.6.1.1 Definition

The amplitude modulation noise level of the aural carrier is expressed as the ratio in dB of the RMS value of the residual amplitude modulation component of the carrier envelope, within the band of modulation frequencies to the RMS value of the carrier, with no input modulation signal.

A2.6.1.2 Method of measurement

Measurement of the amplitude modulation noise may be accomplished by using an AM/FM modulation monitor. The transmitter input terminals shall be shunted with a resistance equal to the source impedance of the audio input circuit. The visual transmitter shall be operated at rated power output and modulated with sync and blanking.

A2.6.1.3 Standard

The ratio shall be at least 50 dB measured in the frequency band from 30 Hz to 15 kHz.

A2.6.2 Synchronous amplitude modulation

A2.6.2.1 Definition

Synchronous amplitude modulation of the aural carrier is expressed as the ratio in dB of the RMS value of the residual amplitude modulation component of the carrier envelope, within the band of modulation frequencies to the RMS value of the carrier, under conditions of frequency modulation.

A2.6.2.2 Method of measurement

Measurement of synchronous amplitude modulation may be accomplished by using an AM/FM modulation monitor. The residual synchronous amplitude modulation is expressed as the ratio of the RMS value of the AC component to the DC component multiplied by 0.707, expressed in dB. The visual transmitter shall be operated at rated power output and modulated with sync and blanking.

A2.6.2.3 Standard

Audio: The ratio shall be at least 40 dB with ±25 kHz deviation by 400 Hz modulating signal.

Composite: The ratio shall be at least 26 dB with ±75 kHz deviation by a 20 kHz modulating signal.

A2.7 Non-linear distortion

This section specifies the requirements applicable to non-linear distortion subject to this standard. Its definition, method of measurement and the limit value to be met are given.

A2.7.1 Audio harmonic distortion

A2.7.1.1 Definition

This form of non-linear distortion is expressed in terms of the output voltage of the harmonics produced from a sine wave input signal.

Total harmonic distortion (THD) is defined as the ratio of the RMS output voltage of the total harmonics to the total RMS output voltage.

Harmonic distortion of audio modulating frequency signals in the range 30 Hz to 15 kHz is specified within the 15 kHz channel and above the 15 kHz channel. The former produces distortion within the main audio channel and the latter produces spurious components above the main audio channel.

A2.7.1.2 Method of measurement

In-channel THD measurements require the use of an aural demodulator with an inherent THD of less than 0.1 %, which is fed from an RF monitoring connection in the aural transmitter output transmission line. A distortion analyser with THD measurement capability within a 30 Hz to 15 kHz range is required.

A 75 µs de-emphasis network in the demodulator is used when testing the audio input which contains a 75 µs pre-emphasis.

The audio output of the aural demodulator is connected through a 30 kHz low pass filter with a minimum slope of 12 dB/octave to the input of a distortion analyser of low residual THD, 0.05 % or less.

Out-of-channel harmonic measurements require the use of a spectrum analyser to observe the output of a demodulator exhibiting flat response from 30 Hz to 120 kHz as specified in paragraph 2.2.4.2.

The audio input signal to the transmitter shall be supplied from a source having less than 0.05 % THD.

A2.7.1.3 Standard

A2.7.1.3.1 In-channel

For modulating signals from 30 Hz to 7500 Hz, the total harmonic distortion, including harmonics up to 15 kHz, shall not exceed 0.5 % with deviations up to ±25 kHz.

A2.7.1.3.2 Out-of-channel

For modulating signals from 30 Hz to 15 kHz any individual harmonic component measured in the frequency range 15 kHz to 120 kHz shall not exceed 0.2% with carrier deviations up to ±25 kHz.

These requirements apply to both the audio input and the composite input modulation terminals.

A2.7.2 Audio difference frequency distortion

A2.7.2.1 Definition

This form of non-linear distortion is expressed in terms of the output voltage of the difference frequency signal produced when two equal amplitude high frequency sine wave signals are passed through a device containing non-linearities.

For this standard, difference frequency distortion is defined as the ratio of the RMS voltage of the difference frequency signal to the RMS voltage of one of the high frequency output signals.

A2.7.2.2 Method of measurement

Two equal amplitude sine wave signals, a 14 kHz signal and a 15 kHz signal are applied to the audio input through a suitable mixing network either from separate audio oscillators or from a combined unit designed for difference frequency measurement. Each signal shall contain less than 0.05 % total harmonic distortion.

The measurement requires the use of a low frequency spectrum analyser and an aural demodulator with an inherent difference frequency distortion of less than 0.1% which is fed from an RF monitoring connection at the aural transmitter output.

Measurements shall be made with ±25 kHz deviation at inputs to the audio and composite terminals.

The demodulator output response shall be ±0.5 dB from 30 Hz to 30 kHz (i.e, de-emphasis shall not be used).

The level of the difference component shall be measured with respect to either of the two input signals. For this measurement, pre-and de-emphasis shall not be used.

A2.7.2.3 Standard

Audio difference frequency distortion shall not exceed 1.0% with a deviation of ±25 kHz. This requirement applies to the audio input and the composite input modulation terminals.

A2.7.3 Composite harmonic and intermodulation distortion

A2.7.3.1 Definition

This form of multichannel non-linear distortion spurious products, including harmonics, sum and difference, and other intermodulation products result from amplitude and phase non-linearities in the aural FM transmission system.

Equivalent deviation of spurious levels in the appropriate frequency bands is given by the ratio of spurious product RMS voltage to a standard reference level RMS voltage.

A2.7.3.2 Method of measurement

Four low distortion (0.05% THD) signals are combined in a summing circuit, which minimizes signal interaction, to drive the composite input terminals at the proper levels to achieve specified deviations.

The aural carrier shall be demodulated with a suitable wideband linear FM discriminator providing a minimum baseband bandwidth of 30 Hz to 120 kHz (preferably 200 kHz). The baseband output shall be displayed on a suitable spectrum analyser, and the spurious signal levels measured referenced to the Fl, 12 kHz signal.

A2.7.3.3 Standard

Multichannel harmonic and intermodulation products are measured with the following channel deviations and frequencies:

Channel Channel frequency (KHz) Deviation (kHz)
F1 12 ±27
F2 31.5 ±30
F3 78.6 ±15
F4 102.3 ±3
  Total: ±75

Maximum spurious product levels, referenced to ±25 kHz deviation shall be as follows:

Frequency band I.M.D. (dB) Deviation (Hz)
30 Hz to 94 kHz -54 50
94 kHz to 120 kHz -48 100
Above 120 kHz -40 250

A3. RF performance standards

This section contains the RF performance standards to ensure quality operation of TV broadcasting equipment. Definitions, method of measurements and technical specifications related to this parameter are given in sub-sections A3.1 to A3.5.

A3.1 RF input impedance - Translator standard

This section describes the technical parameters to be met by the standard RF input impedance of the television translator.

The standard RF input impedance of the television translator shall be 50 or 75 Ω unbalanced. The return loss over the entire input channel shall not be less than 18 dB. This value shall be maintained for input signal levels of 1 mV ±16 dB.

A3.2 Input noise figure - Translator

A3.2.1 Definition

The noise figure is a measure of the noise contribution of the television translator to the overall video and audio signal to noise ratio.

A3.2.2 Method of measurement

The television translator shall be fed with a standard test signal of 1 mV amplitude and the gain control adjusted to obtain rated power output. The input signal shall then be replaced by a signal from a noise figure metre.

A3.2.3 Standard

The noise figure at 1 mV input signal level shall be as follows:

for channels 2 to 13 7 dB maximum
for channels 14 to 69 9 dB maximum

A3.3 Automatic gain control performance - Translator

A3.3.1 Definition

The AGC performance is the ability of a television translator to maintain a given output level while being fed an input signal of varying levels.

A3.3.2 Method of measurement

The translator shall be fed with the standard test input signal of 1 mV (0 dBmV). Vary the level between 0 dBmV and ±16 dBmV. Observe the power output variation.

A3.3.3 Standard

The peak power output level of the television translator shall remain within ±0.5 dB of its rating.

A3.4 Visual to aural cross-modulation - Translator

This section sets out the requirements applicable to visual to aural cross modulation for the translator subject to this standard. Its definition, method of measurement and the limit value to be met follow.

A3.4.1 Definition

The visual to aural cross-modulation is the extent to which a signal modulating the visual carrier also amplitude modulates the aural carrier when both signals are simultaneously passed through the amplifier stages of the television translator.

A3.4.2 Method of measurement

The visual carrier shall be modulated with the standard test signal. The aural carrier shall be unmodulated. An amplitude modulation monitor shall be used to measure the percent amplitude modulation on the aural carrier.

A3.4.3 Standard

The visual to aural cross-modulation shall not exceed 10% peak, i.e. the video information shall not amplitude modulate the aural carrier more than 10% peak in a 15 kHz bandwidth.

A3.5 Aural to visual cross-modulation - Translator

A3.5.1 Definition

The aural to aural cross-modulation is the extent to which the audio information modulating the aural carrier also modulates the visual carrier.

A3.5.2 Method of measurement

The visual carrier shall be modulated with a staircase signal. The aural carrier shall be unmodulated with 4000 Hz signal at a deviation of ±25 kHz. Observe the detected video signal on a waveform monitor at a field rate. Measure the presence of audio on the staircase steps.

A3.5.3 Standard

The aural to visual cross modulation shall be 50 dB below the peak to peak video signal.

Figure A1: Standard composite color video signal

Description of Figure A1

The figure shows the standard composite colour video signal. A waveform illustrating different amplitudes related to duration of periods is plotted. The amplitude in IRE units is shown vertically and the duration of different periods such as lien blanking, line synchronization and active line, horizontally. The waveform signal limits are -40 to +120 IRE. 

At the right side of the figure, there is a scale representing the carrier in percentage (%). The carrier scale is between 0 to 100% of peak of SYNC level, being 12.5 % the reference white level and 75% the blanking level. At the left side of the figure, there is a average picture level (APL) scale in percentage. The APL scale limits are 0 to 100 %. Below the figure, there is the list and description of the waveform terminology used.

 

Waveform terminology:

A: 
       Peak-to-peak amplitude of the composite video signal
B:      
  Difference between black level and blanking (set-up)
C:   
     Peak-to-peak amplitude of the color burst
D:   
     Luminance signal-nominal value
M:   
    Monochrome video signal peak-to-peak amplitude (M=L+S)
S:   
      Synchronizing signal - amplitude Tb Duration of breezeway
Tb1: 
   Duration of lien blanking period 
Tsy:  
   Duration of line synchronization
Tv:   
   Duration of active line period

Figure A2(a): Staircase test signal

Description of Figure A2(a)

The figure plots the staircase test signal. The amplitude of the signal in IRE units is plotted on the y axis. Its limits are -40 to +100 IRE. Three different staircase signals at 50 %, 10 % and 90 % average picture level (APL) and starting at the 0 IRE level are plotted as follows: 

  • Staircase waveform of 50% APL: a sequence of a five discrete steps up stair with an amplitude of 100 IRE is followed by one -40 IRE pulse. 
  • Staircase waveform of 10% APL: a five discrete steps up stair with an amplitude of 100 IRE is followed by one -40 IRE pulse. This pulse is periodically repeated at an interval equal to the stair duration.
  • Staircase video waveform of 90% APL: a five discrete steps up stair with an amplitude of 100 IRE is followed by a -40 IRE pulse. Then a100 IRE pulse follows and alternates with the -40 IRE pulse. The sequence is repeated. 
 

Figure A2(b): Staircase test signal with color subcarrier

Description of Figure A2(b)

The figure plots the staircase test signal with color subcarrier. The amplitude of the signal in IRE units is plotted on the y axis and its limits are -40 and +100. The color subcarrier is illustrated on the x axis at 0 IRE units. Three different test signals at 50 %, 10 % and 90 % average picture level (APL) are plotted as follows:

  • Staircase video waveform of 50% APL: a sequence of a five discrete steps up stair with an amplitude of 100 IRE is followed by one -40 IRE pulse. The stair shows a differential gain within the 90 to 100% APL range.
  • Staircase video waveform of 10% APL: a five discrete steps up stair with an amplitude of 100 IRE is followed by one -40 IRE pulse. This pulse is periodically repeated at an interval equal to the stair duration. The stair shows a differential gain within the 90 to 100% APL range.
  • Staircase video waveform of 90% APL: a five discrete steps up stair with an amplitude of 100 IRE is followed by a -40 IRE pulse. Then a100 IRE pulse follows and alternates with the -40 IRE pulse. The sequence is repeated. The stair shows a differential gain within the 90 to 100% APL range. 
 

Figure A3(a): Low pass filter (fc =4.2 MHz)

Description of Figure A3(a)

The figure shows a low pass filter circuit with a cut-off frequency (fc) equal to 4.2 MHz. The different components and values of the filter are given in the figure. 

 

Inductances are given in µH and capacitances in pF 
Q measured at 5 MHz is between 80 and 80 and 125 for all inductors

Figure A3(b): High pass filter (fc =10 kHz)

Description of Figure A3(b)

The figure shows a high pass filter circuit with a cut-off frequency (fc) equal to 10 MHz. The different components and values are given in the figure. 

 

Inductances are given in µH and capacitances in pF 
Q measured at 10 KHz should be 100 or more

Figure A4: Group delay requirements

Description of Figure A4

The figure is a plot illustrating group delay requirements. The group delay in nanoseconds (ns) is plotted on the y axis versus the frequency above picture carrier in MHz on the x axis. The axis limits are 0 to 4.18 MHz and - 400 to +100 ns, respectively. There are three different group delay curves identified as lower limit, reference and upper limit. The group delays values and frequencies are plotted as follow: ±50 ns, ±35 ns, ±25 ns and ±50 ns at 2 MHz, 3 MHz, 3.56 MHz, and 4.18 MHz, respectively.

 

Figure A5(a): Composite test signal

Description of Figure A5(a)

The figure is a plot of a full field composite test signal. The signal is plotted in IRE units on the y axis versus the nominal timing in microseconds (µs) on the x axis. The axis limits are -40 to +110 IRE and 0 to 62 µs, respectively. 

 

Figure A5(b): Graticule A

Description of Figure A5(b)

The figure shows graticule A. The figure is a photographic reproduction of standard NTSC type A graticule used to measure the K pulse to bar (Kpb) rating. 

 

Figure A5(c): Kpb rating vs 2T pulse amplitude

Description of Figure A5(c)

The figure is a plot illustrating the K pulse to bar (Kpb) rating versus 2T pulse amplitude. The 2T pulse amplitude in IRE units is plotted on the y axis versus Kpb rating percentage (%) on the x axis. The axis limits are 0 to 130 IRE and 0 to 17%, respectively. A curve with two segments intercepting at 2T pulse amplitude of 100 IRE is depicted as follows:

  • an upper segment of the curve plotted from 0 to 17%. This segment shows the 2T pulse amplitude climbing from 100 IRE to beyond 130 IRE, and
  • a lower segment of the curve plotted in the same range shows the 2T pulse amplitude descending from 100 IRE to slightly below 60 IRE.
 

Figure A5(d): Graticule B

Description of Figure A5(d)

The figure is a reproduction of the standard NTSC type B graticule used to measure the K rating of the 2T pulse (K2T). 

 

Figure A6: Applications nomograph for 12.5 T pulses

Description of Figure A6

The figure is a nomograph adjusted for 12.5 T pulse. It is represented by the relations between the chrominance-luminance amplitudes Y1 and Y2 in dB, the video signal amplitude in IRE units and the timing of the chrominance-luminance components of the signal in ns. The limits are -3.0 to +3.0 dB, 0 to 24 IRE and 50 to 350 ns, respectively. There are a few scales arranged in a way that the value of the relative delay change can be found by noting the displacement of the baseline by the amplitudes Yl and Y2.

 

Appendix A: Standard output signal system M/NTSC

Figure A7: Standard output signal system M/NTSC

Description of Figure A7

The figure shows the standard television signal as specified for M/NTSC system. Four signals are represented. In the horizontal plane, particular periods of time such as the time from start of one line/field to start of the next line/field, equalizing pulse, and horizontal sync pulse are illustrated. In the vertical plane, amplitudes like the peak excursion of the luminance signal from blanking level, sync amplitude above blanking level, and peak carrier are plotted. Below the figure, there is a list of the terminology used and additional details of the standard output signal system M/NTSC.

 
  1. H = Time from start of one line to start of next line;
  2. V = Time from start of one field to start of next line; 
  3. Leading and trailing edges of vertical blanking should be complete in less than 0.1hours; 
  4. Leading and trailing slopes of horizontal blanking must be steep enough to preserve minimum and maximum values of (X +Y) + (Z) under all conditions of picture content; 
  5. Tolerances given are permitted only for long time variations and not for successive cycles; 
  6. Equalizing pulse area shall be between 0.45 and 0.5 of area of a horizontal sync pulse;
  7. Colour burst follows each horizontal pulse, but is omitted following the equalizing pulses and during the broad vertical pulses;
  8. The burst frequency shall be 3.579545 MHz ± 10Hz with a maximum rate of change of frequency not to exceed 0.1 Hz;
  9. The horizontal scanning frequency shall be 2/455 times the burst frequency; 
  10. The dimensions specify for the burst determine the time of starting and stopping of the burst, but not it’s phase. The colour burst consists of amplitude modulation of a continues sinewave; and
  11. Dimension “P” represents the peak excursion of the luminance signal from blanking level but does not include the chrominance signal. Dimension “S” is the sync amplitude above blanking level. Dimension “C” is the peak carrier amplitude. 

Appendix B: Standard pre-emphasis curve time constant 75 µs (Solid line)

Figure B1: Frequency response limits shown by use of solid and dashed lines

Description of Figure B1

The figure is a plot illustrating a pre-emphasis curve standardized with a 75 μs pre-emphasis curve.

The audio signal level response in decibels (dB) is plotted on the y axis versus audio signal frequency in Hertz (Hz) on the x axis. The axis limits are -4 to +20 dB and 20 to 20000 Hz, respectively. There are three curves depicted as follows:

  • a flat solid line becoming a concave up curve around the 250 Hz. The curve increases logarithmically. The audio signal level response at the 100, 1000 and 10000 Hz are -1, 0 and 13 dB, respectively. 
  • two dashed lines becoming concave up curves around the 350 Hz. The curves increase logarithmically about the 350 Hz. The audio signal response of the lower curve plotted below the solid line at the 100, 1000 and 10000 Hz are -1, 0 and 14 dB, respectively. The response of the upper curve plotted above the solid line at the 100, 1000 and 10000 Hz are1, 2 and 15 dB, respectively.