Voyager with path loss

Body

Voyager transmits with 18W (rewasonably loud - about the same as an average cellphone basestation, but a lot less than a TV station) Antenna gain is 48dBi to give EIRP of:
18 W (42.5 dBm) + 3.74 m (48.2 dBi) = 90.7 dBm (1 MW) carrier suppression -6 dB: 84.7 dBm The path loss is ASTONISHING... 1 AU distance ‡ path loss = 274.4 dB 1.5 AU (Venus today) ‡ path loss = 276.2 dB 2.5 AU (Mars Today) ‡ path loss = 278.8 dB 100 AU distance ‡ path loss = 314.4 dB
 
The team in the link used a university 20m antenna

 

 
Voyager 1 
TX 84.7 
Path Loss 314.4 
Antenna Gain 61.9 
Noise -175
SNR (1Hz) 8.0

to get a signal with net net SNR of +8.0dB on 1Hz

These things are so ludicrously small we run out of greek prefixes, and even scientific notation is less useful than dB)



 

 

So even at 100AU, with "only" 735 seconds acquisition and "only" a 20m dish you can detect Voyager


But sooner or later, the acquisition time and the antenna size become impractical...