Analyze satellite-to-ground communication links with complete transmitter, path, and receiver calculations
Satellite or spacecraft transmitter parameters
= 6.99 dBW (36.99 dBm)
Antenna directional gain (dipole ~2 dBi, patch ~6 dBi, dish ~30+ dBi)
Losses between transmitter and antenna
Propagation path between satellite and ground station
LEO ~500 km, MEO ~20,000 km, GEO ~36,000 km
Antenna misalignment loss
Ground station or receiving terminal parameters
Small dish ~20 dBi, large dish ~40+ dBi, DSN 70m ~74 dBi
Cooled LNA ~100K, typical ground station ~200-400K
Feed, cable, and implementation losses
Data rate and modulation scheme
= 10.0 Mbps
| Parameter | Value | Linear |
|---|---|---|
| Transmit Power | 6.99 dBW | 5 W |
| Transmit Antenna Gain | +6.00 dBi | 4.0x |
| Transmit Losses | -1.00 dB | |
| EIRP | 11.99 dBW | 15.81 W |
| Free Space Path Loss | -153.28 dB | 2.2 GHz, 500 km |
| Atmospheric Loss | -0.50 dB | Clear sky estimate |
| Pointing Loss | -0.50 dB | Antenna misalignment |
| Receive Antenna Gain | +34.00 dBi | 2511.9x |
| Receive Losses | -1.00 dB | |
| System Noise Temperature | -24.62 dB-K | 290 K |
| G/T (Figure of Merit) | 9.38 dB/K | |
| Boltzmann Constant (k) | +228.60 dBW/K/Hz | 1.38 x 10⁻²³ W/K/Hz |
| C/N₀ | 94.69 dB-Hz | Carrier-to-noise density |
| Data Rate | -70.00 dB-bps | 10.0 Mbps |
| Eb/N₀ (Actual) | 24.69 dB | |
| Required Eb/N₀ (QPSK) | 9.60 dB | BER = 10⁻⁶ |
| Link Margin | 15.09 dB | Healthy |
EIRP (dBW)
= P_tx (dBW) + G_tx (dBi) - L_tx (dB)
Free Space Path Loss (dB)
= 20 log10(4 pi d f / c), where d = distance (m), f = frequency (Hz)
G/T (dB/K)
= G_rx (dBi) - 10 log10(T_sys) (K)
C/N0 (dB-Hz)
= EIRP + G/T - FSPL - L_atm - L_rain - L_point - L_rx - k
where k = -228.6 dBW/K/Hz (Boltzmann constant)
Eb/N0 (dB)
= C/N0 - 10 log10(R), where R = data rate (bps)
Link Margin (dB)
= Eb/N0 (actual) - Eb/N0 (required)