Determination of a signal loss profile relative to a receiver based on measured signal power of a sounding signal from a sounding transmitter having a known signal power in free space relative to the receiver. The signal loss profile may include a plurality of signal loss values corresponding to a plurality of received sounding signals at the receiver. In an embodiment, the sounding signal may comprise a GNSS navigational signal (e.g., a GPS signal). The signal loss profile may be used to extrapolate signal loss for a transmitter collocated with the receiver. In turn, the signal loss profile may be used in conjunction with a shared spectrum system to model a signal propagation from the collocated transmitter when determining allocation of a shared spectrum resource of the shared spectrum system.