Appendix 8 – Planning Factors for DTV Reception
The planning factors shown below led to the values of field strength given in tables 1 and 2 of Section B. The field strength values are found by solving the equation:
\(Field (dB\mu V/m) = C/N - K_{d} - K_{a} - G + L + N_{t} + N_{s} \)These planning factors are assumed to characterize the equipment, including antenna systems, used for home reception. They determine the minimum field strength for DTV reception as a function of frequency band and as a function of channel number in the UHF band.
| Planning Factor | Symbol | Low VHF | High VHF | UHF |
|---|---|---|---|---|
| Geometric Mean Frequency (MHz) | F | 69 | 194 | 615 |
| Dipole Factor (dBm-dBμV/m) | Kd | −111.8 | −120.8 | −130.8 |
| Dipole Factor Adjustment | Ka | None | None | See Text |
| Thermal Noise (dBm) | Nt | −106.2 | −106.2 | −106.2 |
| Antenna Gain (dBd) | G | 4 | 6 | 10 |
| Downlead Line Loss (dB) | L | 1 | 2 | 4 |
| System Noise Figure (dB) | Ns | 10 | 10 | 7 |
| Required Carrier to Noise Ratio (dB) | C/N | 15 | 15 | 15 |
The adjustment, Ka = 20 log[615/(channel mid-frequency in MHz)], is added to Kd to account for the fact that the field strength requirements are greater for UHF channels above the geometric mean frequency of the UHF band and smaller for UHF channels below that frequency.