China 2 telemetry on 19.995 MHz

The signal consists of a train of pulses. Some pulses define constant time periods (telemetry words) within which an additional pulse appears. The word length is 0.3125 sec. The position of this additional pulse (marked with a red dot in the picture bove) within the the word interval defines the measured value. There are 16 such word intervals in a "frame" that lasts 5.0 seconds. Two word intervals are usd for synchronization, so 14 useful words are available in each frame. This type of telemetry is called PPM-AM (Pulse-Position Modulated Amplitude Modulation). The advantage with PPM-AM is that it requires very little power. The duty cycle of the transmitter is very low!

Listen to the telemetry frame above by clicking here.

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