VLF: ebsynth

[Markus Vester <markusvester@aol.com>]

Hi Paul,

 

I'm wondering if you'd want to use GPS and RF feedback to stabilize the phase? Connecting 1pps and an antenna probe to a stereo input soundcard would allow you to monitor the emitted phase and adjust the oscillator accordingly. That way you'd have control over absolute phase, compensating for dropouts, samplerate crystal variations and antenna tuning. For non-integer Hz carrier frequencies you'll also need a way to identify which second a pulse belongs to, e.g. by means of NTP time or GPS messages.

 

I'm not knowledgeable about Linux but at least have managed to run a soundcard on a RasPi. It would be nice to use it for stable carrier and PSK signal generation.

 

> There was a gap in the rain on Sunday so I put up a 200 metre long wire.

 

Great! Should we start looking for your signal on 477.700 kHz?

 

All the best,
Markus

-----Original Message-----
From: Paul Nicholson <vlf0403@abelian.org>
To: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Sent: Mon, Feb 8, 2016 8:36 pm
Subject: Re: VLF: EbNaut 8270.1 Sunday
... 
Here I've been playing with ebsynth which is now 
at version 0.5 and has some improvements.  It uses 
much less CPU and does the phase modulation using 
a sigmoid shaped slew. 
 
  http://abelian.org/ebnaut/ebsynth.shtml 
 
I built a multiplier chain, 53077.777778 * 3 * 3 and 
have a nice 10V 477 kHz signal which is rock steady 
and the modulation clicks don't seem to spread. 
 
There was a gap in the rain on Sunday so I put up a 
200 metre long wire. 
 
-- 
Paul Nicholson 
--