Re: LF: Coherent receivers and EbNaut

[Andy Talbot <andy.g4jnt@gmail.com>]

Ok.

Enhanced .WAV is ideal - no need for yet another file format.

In fact, having a redundant original header block could be useful.  If, for example, the sampling rate value in that is programmed for, say, 1000 times the slow rate, it might provide possibilities for playing the .WAV back as an audio file, speeded up without extra processing

I remember doing this many years ago with Dopplergrams generated via Motorola DSP cards, and saving I/Q data at low sampling rates in a custom format.  The data was then upconverted and played back at a suitable sample rate.   The Ionospheric Doppler shifted carriers, originally consisting of many hours of recording, generated some wonderfully surreal  sounds when played back compressed into a couple of minutes.    Some were reminiscent of whale noises.

Andy  G4JNT

On 8 November 2015 at 21:02, Paul Nicholson <vlf0403@abelian.org> wrote:

> if I publish the serial protocol, would it be feasible for
> Ebnaut to be modified to accept the data directly?

Feasible yes, but I wouldn't recommend it.   I advise
recording the signal first, then present the recording
to the decoder.  This, so you can repeatedly run the
decoder with different frequency and time offsets if
necessary in order to cope with some clock or oscillator
offset at the transmitter, or to try a 15 deg phase
search if the 30 deg doesn't turn anything up.

You don't have to use WAV.  Define your own file format
in which to capture your serial data, and I'll make
ebnaut-rx handle the file when it sees a .JNT extension.

Hmm, also ebnaut-tx could have an option to output
a .JNT file, for test purposes or to drive your tx.
--
Paul Nicholson
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