A projectile fuze sends a signal having encoded telemetry data. The telemetry data may be encoded by modulating an aspect or characteristic of the signal, such as frequency modulation of the signal. The fuze may receive and interpret reflections in order to determine proximity to a target or other object, such as by functioning as a height of burst sensor. The signal may include a series of random or seemingly random pulses (a keyed pattern of pulses), such as pulses in amplitude of the signal. The fuze includes a pair of transceivers for sending signals of different frequencies through an antenna, and for receiving signals through the antenna. The transceivers are configured such that one or the other is used at any one time when telemetry data is sent, with telemetry being encoded by changes in frequencies.