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Community Script

Scan - COA

Scan around defined Centres of Activity (COA).

This script will cycle through list of COAs, scanning the prescribed frequency range around each one.

Scanning may be stopped either by pressing the stop button, or by keying your key, dah paddle or mic (anything which briefly puts the radio into TX mode);

note

Stopping the scan with the paddle was an interesting exercise. The only way I could determine to do so was to poll the TX state of the tranceiver, but for consistent behaviour the polling should be longer than the TX duration, lest the keying TX fall in the gap between two polls. The way around this was to calculate the minimum expected duration of a keyed TX and poll fractionally faster.

The calculations are:

  • tdit = 60 / (50 * wpm)
  • tdah = 3 * tdit

I decided a reasonable maximum speed was 35 wpm, which works out at:

  • dit: 34 ms
  • dah: 102 ms

As such, I've set the TX monitor to poll at 100 ms intervals to cater for the dah key. One may still use the dit key, but with only a 1/3 chance of the scan stopping.

Configuration​

Edit the following variables at the top of the script to taste:

  • FREQ_LIST: The centres of activity you wish to scan.
  • SCAN_SPAN: How far above and below the COA frequency to scan.
  • STOP_ON_TX: Should scanning stop on TX? ⚠️ Note that on some android devices the extra overhead of checking the TX state at a rate of 100 ms may lead to lumpy scanning and TX state change being missed.