I’m developing a pilot-activated airport weather advisory system using the following equipment:
- · Yaesu FTA-250L handheld aviation radio
- · Digirig Lite USB interface
- · Raspberry Pi running Python
- · Connection through the radio’s external microphone/speaker accessory jack
The system listens for a pilot’s spoken weather-report request, retrieves current weather information, and transmits a spoken advisory after the pilot releases the PTT button.
The basic system is working, including audio reception, speech recognition, and Digirig-controlled transmission.
My question concerns reliable detection of an occupied radio frequency.
Currently, the Python program monitors received audio levels to determine when a transmission has ended and whether the frequency is clear.
However, a pilot could continue holding the PTT button without speaking. In that situation, the audio may be silent even though the frequency is still occupied.
The receiving FTA-250L does not provide any visible or audible indication that I can identify when another radio transmits an unmodulated carrier.
My questions are:
- Is there a way to obtain carrier-detect (COS/COR) or squelch-status information through the Digirig Lite?
- Does the FTA-250L provide any usable carrier-detect signal through its external microphone/speaker connector?
- Has anyone developed a reliable method of distinguishing a silent carrier from an idle frequency using a Digirig interface?
- Would additional hardware be necessary, and if so, what approach would you recommend?
The objective is to prevent the automated weather system from transmitting while another pilot is occupying the frequency.
Any suggestions or experience with this equipment would be greatly appreciated.
Thank you!