From: <hvanesce@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
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In-Reply-To: <945d5f49-3fc4-d7c1-fecc-196e7c3ac8dd@abelian.org>
Date: Wed, 15 Feb 2017 18:45:39 -0500
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Subject: RE: LF: Raspberry Pi sound interface that works
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Paul, 

Thanks for posting your findings on this topic. 

Plenty of the Audio Injector boards on local Amazon so I bought four in hopes that your tests would prove favorable. Thanks for the favorable results!

I haven’t worked with a Raspberry Pi before but have a new CanaKit RPi 3 and though I would use it with the Audio Injector module. Then I saw your message indicating disinclination toward RPi 3 power dissipation (from unused built-in Bluetooth and WiFi). I had guessed that the RPi would be used to enable a wireless connection between antenna and laptop/PC, which raises a question (if you have a moment): for a backyard-antenna-to-indoor-laptop application or for a portable field-test application, what type of interface would be used between an outdoor RPi 2 and an indoor laptop or portable-field-test laptop?  (or am I on the wrong track; should I be thinking of Audio Injector plus  RPi 2as an unattended datalogger rather than a real-time interface between VLF loop and laptop?)

Thanks,

Jim AA5BW


-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Paul Nicholson
Sent: Wednesday, February 15, 2017 5:02 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Raspberry Pi sound interface that works


Another update to EbSynth, now at version 0.7a

  http://abelian.org/ebnaut/ebsynth.shtml

Now compensates properly for changing delay of the output buffer as the sample rate wanders.  A temperature change that previously produced a 30 degree output change now only affects the phase by about 0.3 degrees. The residual is a 2nd order effect proportional to the rate of change of sample rate.

I've noticed a couple of sound card input overruns on the RPi when the CPUs are very busy.  0.7a assigns itself a real-time scheduling policy at high priority.  It remains to be seen if that fixes the overruns.

--
Paul Nicholson
--