Low-cost hardware solution for PCM/FM telemetry data encoder based on IRIG-106 standard

The PCM telemetry data encoder, part of the PCM/FM transmitter system used in rocket telemetry, follows the IRIG-106 standard. It collects data from sensors that monitor flight parameters like inertia, combustion pressure, and vibration. These encoders are usually developed by defense industries, with limited public details and a high cost of around $30,000 per unit or nearly 500 million rupiah in 2011. This paper presents a low-cost alternative using an STM32 microcontroller for under $30, capable of handling telemetry data at 1.024 Mbps. The hardware design was validated through a proof-of-concept using MATLAB Simulink and LTspice simulations and tested with a Zodiac TRFM02-S FM transmitter and Cortex RTR S-Band receiver. The test performance was compared with the Zodiac CMA, a telemetry encoder originally manufactured by Zodiac Data Systems and now produced by Safran, which also follows the IRIG-106 standard. Results showed no significant difference in BER between the two systems, although the low-cost solution had a slightly lower quality factor. It required a 1% loop bandwidth for similar performance, while the CMA only needed 0.3%. Despite this, the low-cost design is still effective for telemetry use, as it remains within the receiver’s maximum allowable loop bandwidth of 3%.