A Transit-Beacon Receiver: Link Budget, Sensitivity and Acquisition Behaviour for Phase-Step Beacon Signals

A beacon organised by the transit law's phase steps is only as useful as the receiver that can find it: a narrowband, structured signal that must be acquired against Doppler uncertainty and noise. This paper specifies the companion receiver to such a beacon and computes its link performance end to end. With a 0.60-metre dish of gain 21.0 decibels and a system temperature of sixty kelvin, a forty-decibel-watt beacon gives a received power of -99.1 decibel-watts at one thousand kilometres, a signal-to-noise ratio of 111.7 decibels in one hertz; at one astronomical unit the received power is -202.6 decibel-watts and the ratio 8.2 decibels, above the ten-decibel detection requirement. A full Doppler search of plus or minus fifty kilohertz completes in 10 seconds. SIMULATED, NOT MEASURED: the receiver is specified and computed, and no beacon signal has been received.