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Re: LF: EbNaut beaconing on LF

To: [email protected]
Subject: Re: LF: EbNaut beaconing on LF
From: Paul Nicholson <[email protected]>
Date: Thu, 9 Feb 2017 23:34:46 +0000
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Riccardo wrote:

> in fact the bandwidth on your grabber seems larger
> than Domenico's EbSynth test signal.

The ebsynth settings Domenico is using produce BPSK where
the phase is slewed from one polarity to the other.  It takes
0.05 of a symbol period to change phase.  This is intended to
limited the keying transients of the signal when operating at
LF or above (on VLF, hard keying is no problem, nobody will
complain about the sidebands - you can just use a relay!).

I don't really know how effective that slewing is, ebsynth
hasn't had much air time.  Reports welcome!  I can use some
other method to constrain the bandwidth if necessary.

Testing a mod to ebsynth to control the PTT via com port modem
control lines.  It works nicely but for one obscure test case:
a soundcard with a long output buffer (eg 5.4 seconds on a AUD
20101 USB dongle) combined with a message which is so short
that it fits entirely in the buffer.   I have an ugly fix for
this case, but the fix would fail if you also set a repeat
time so short that more than one message was in the output
buffer.  The solution for that is uglier still.  I'll sleep on
the problem and in the morning I will have an elegant solution
that handles the craziest combinations of long buffers and
rapid fire messages.

Paul Nicholson

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