v1.561: audio pre-record, squelch zero button, SAM options fix

From the CHANGE_LOG file.

The pre-record stuff is not perfect. But wanted to get it out there to be able to play around with real signals.

v1.560,561 Sep 13, 2022

  New audio "pre-record time" menu (located to the left of the squelch tail length menu).

  Allows audio samples stored from before the "record" button is pressed, or before the

  squelch opens, to be included in file recordings.


    Handy for when you hear something you want to record but it takes you a few seconds to hit

    the record key ('r') or click the record button. Or you find critical content missing from

    the recorded file because the squelch opens too slowly (e.g. preamble to a data burst).


  The (non-NBFM) squelch has this feature/problem that it only responds to relative changes in

  signal strength. For example, if it is set to 10 dB then the squelch will only open when there

  is a 10 dB *increase* in signal strength. This means if you had a non-zero squelch value set

  while tuned to a strong signal, and then reload the page, the squelch remains open (no audio).

  This happens because there has never been a 10 dB increase in signal strength from the

  squelch's perspective.

    To fix this you must tune to a quiet part of the band, set the squelch to zero to establish

    the noise floor, then set it back to the desired value (10 dB in our example).

    To make this operation easier a new button just before the squelch slider will momentarily

    zero the squelch value while pressed. Wait a few seconds with the button pressed for the

squelch to establish a new noise floor.


    In case you're wondering, the NBFM squelch doesn't have this problem because it constantly

    measures the threshold noise power above the voice frequencies in the FM channel. So it

    is able to make a continuous relative measurement. This is difficult in the non-NBFM

    environment. Somewhat related to our difficulties in automating SNR measurement.

  "SAM options" menu now works for the other SAM modes (SAL, SAU, SAS, QAM).


  S-meter extension now has its own menu for setting the timestamps to UTC or local time.

  Previously the value from the waterfall extension UTC/local menu was used.


  Waterfall and S-meter timestamps now appended with "UTC" or "L".

  Fixed a somewhat strange problem with proxied Kiwis: If you had a low value in the menu on the

  admin control tab "Number of simultaneous channels available for connection by non-Kiwi apps"

  (like "none" or "1") then some non-local, legitimate browser connections would sometimes get

  flagged as a "non-Kiwi app" and denied a connection. The details are hard to explain.


    Anyway, it is fixed. So if you had to increase the menu value as a workaround you should be

    able to decrease it again. A lower value is helpful if you have lots of bots connecting that

    you're trying to limit (the bots are classified as non-Kiwi connections). You usually want

    at least one non-Kiwi connection to handle legitimate TDoA or kiwirecorder use.


    As usual, connections from the local network are exempt from all this. So for example

    wsprdaemon running on an RPi on the local network won't be subject to this limit.  


  • Hi John,

    Thanks for the latest updates and especially the 'pre-record" feature.

    I've been using it to monitor some HF aircraft comms today and it's made a world of difference.



  • Hi John,

    Just one small observation.

    When the squelch tail option is used in conjunction with pre-record, this seems to introduce a period of muted audio.

    Maybe the when both options are selected, the squelch tail should consist of un-muted audio in order to avoid 'chopping' up the recording.



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