FM systems in high-speed or maneuvering aircraft can be affected by Doppler-induced phase and frequency shifts, especially when the aircraft is moving relative to the transmitter or rapidly changing direction. While most open-source discussions focus on FM capture effect and baseband modulation, there’s real engineering literature out there that addresses Doppler effects on FM signal coherence, phase noise, and demodulation fidelity — particularly in the context of military aviation, missiles, and radar.

📚 Where to Look:

1. MIL-STD & DoD Technical Reports:

   • MIL-STD-188 (esp. MIL-STD-188-141 for HF comms) and MIL-STD-461 sometimes touch on link reliability under dynamic conditions.

   • Look for terms like frequency-agile FM, coherent FM detection, and Doppler spread.

2. NASA & DoD Technical Libraries:

   • The NASA Technical Reports Server (NTRS) and DTIC.mil (Defense Technical Information Center) have publications related to Doppler effects in airborne communications.

   • Example: NASA TN D-6570 discusses FM performance under Doppler for tracking applications.

3. IEEE Xplore / AIAA Library:

   • Search for papers on airborne FM telemetry, phase-locked FM under Doppler, or angle-of-arrival degradation in fast-moving FM receivers.

4. Textbooks:

   • “Digital Communication by Satellite” (e.g., Pratt, Bostian, Allnutt) includes good discussion of Doppler in FM satellite and airborne links.

   • “Telecommunication Breakdown” by Johnson touches on non-coherent FM demod in dynamic channels.

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🧠 Key Insight:

Doppler shifts in military aviation can cause the FM carrier to drift outside the receiver’s loop tracking bandwidth, degrading demodulation or increasing bit error rates in FM/FSK systems. Most military systems today lean toward spread spectrum, digital phase modulation, or frequency-hopping to mitigate those effects — but older FM voice or telemetry links (e.g., S-band or UHF) definitely encountered this problem.

If you’re digging into historical systems (e.g., analog avionics, telemetry links, or even ECM systems), this is a real issue and probably documented in older classified or export-controlled material that’s now declassified.