PDS computes the full RF link budget for receiving deep-space probe carrier signals with an amateur dish โ from spacecraft EIRP through free-space path loss to coherent SNR at the detector. Developed by Alex K6VHF / Deep Space Exploration Society. MIT License.
Pr = EIRP + G_rx โ FSPL โ L_rx
C/Nโ = Pr โ 10ยทlog(kยทT_sys)
C/N(RBW) = C/Nโ โ 10ยทlog(RBW)
SNR_coh = C/N(RBW) + G_coh
where G_coh = 10ยทlog(ฯ) for drift-corrected integration
Corrected: G = 10ยทlog(ฯ) dB/decade โ full gain when Doppler drift is compensated.
Uncorrected: Gain is limited by ฯ_max = โ(RBW/drift). Beyond this, signal smears across bins and SNR degrades.
Components mode: Enter dish diameter, efficiency, T_ant, NF. G_rx and T_sys computed from first principles.
G/T mode: Enter the combined figure of merit G/T directly (typical for known station specs).
SNR > 0 dB in a single RBW bin = detectable above noise. In practice, SNR > 3โ6 dB recommended for confident detection. WSJT weak-signal modes extend this to โ30 dB with longer integration.
EIRP values are approximate for the carrier tone. Most deep-space missions use PSK or PM modulation โ the carrier typically receives 2โ3 dB less power than total EIRP. Enable the modulation loss field to account for this. Ranges shown are approximate values near the time of writing; use NASA Horizons for precise current ranges.