Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HTML_MESSAGE,RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id v69AmPKQ003237 for ; Sun, 9 Jul 2017 12:48:27 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dU9h4-0007AT-Ra for rs_out_1@blacksheep.org; Sun, 09 Jul 2017 11:44:02 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dU9gx-0007AK-FW for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 11:43:55 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dU9gu-0008NK-BK for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 11:43:54 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 9DF0220AE3 for ; Sun, 9 Jul 2017 12:43:49 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3x54hP0fXxzypX for ; Sun, 9 Jul 2017 12:43:48 +0200 (CEST) Message-ID: <596208E4.5060803@posteo.de> Date: Sun, 09 Jul 2017 12:43:48 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <15ca21dc75e-1e15-bcda@webprd-m105.mail.aol.com> <0f9558b4-457d-a395-58c9-7f9be3393cdd@sky.com> <4767d79f-2bf6-d838-bfd4-3e78102d6f5d@abelian.org> <510c15eb-b57a-0ebb-9037-1f83e0652cf2@sky.com> <933fcc32-d4c9-10cd-14b4-c179d66e27f9@abelian.org> <7ab80e0f-40d7-6b07-19c1-f4b256d47c52@sky.com> <594DB217.8060707@posteo.de> <2eb826d6-d299-7b37-cf64-f5bef6718f24@abelian.org> <595E4420.7060405@posteo.de> <595FB81A.5090606@posteo.de> <45775d6c-f091-37c0-0907-f01688c69b03@abelian.org> <5960BAC0.7000403@posteo.de> <5960D0B2.7030801@posteo.de> <6c1f8a0c-0dd6-ed42-cfe6-4a142e7bd3cd@abelian.org> <6991700d-fd34-7676-a182-507ea0fdae8e@abelian.org> In-Reply-To: <6991700d-fd34-7676-a182-507ea0fdae8e@abelian.org> X-Scan-Signature: fce77e88417377663dedf94f027ec622 Subject: Re: LF: Octo-soundcard for the Raspi, another question Content-Type: multipart/alternative; boundary="------------030908020308020409030102" X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: X-Keywords: X-UID: 12203 This is a multi-part message in MIME format. --------------030908020308020409030102 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Paul, thanks for the analysis and the tutorial :-) Am 09.07.2017 07:46, schrieb Paul Nicholson: > What signal voltage does your DDS put into the Octo? It was at 10 mV +- 0.5 mV. > > What input gain is alsamixer set to? All channels set to 49/100, this is +6.5 dB gain. Am 08.07.2017 19:38, schrieb Paul Nicholson: > We can just see a slight change to the ch1 amplitude > which lasts about 100mS. OK, so no loss of samples, rather an AM component. That's not so dramatic. Anyway, let's find the problem. Likely to be an EMC effect. I will have a look on the pcb and will eventually re-solder some pins. It would also be useful to stream CH1 and CH2 via the LAN so i can watch it into SpecLab in real time. Then i could use some cooling spray to seach for bad solder contact. Often it also helps just to touch the contacts with the finger and see for any differences. It started my radio 'carrer' that way ;-) : In 1993, when i was 17 yrs old, a friend donated me a damaged *CB*-transmitter. I simply touched the pcb everywhere until i found a region where the noise started to sound different. Suddenly i heared some people talking!!!!! I replaced a capacitor and it worked again... So far i didn't manage to send a stream over the network to receive it on my windows PC in SpecLab. Maybe you have an idea? :-) I saw the notes on the vlfrx tools documentation site of course, but didn't spend enough time on that so far it seems. > Just shows a steady phase drift, we're not quite on frequency here > with this recording This is due to my undisciplined DDS VFO. > - did it go through vttime? Unintentionally not. vtcard sends to a buffer @raw, vttime takes from @raw and sends to @locked. I disabled vttime for an earlier test and put vtresample to @raw instead of @locked. Forgot to correct that for the test. But it doesn't matter for getting the glitches. > Curious. Signal goes up, background noise drops. I wonder if > there is a dodgy input capacitor or dry joint. Not sure about > that explanation, it would be odd to see the same on more than > one channel. Right. I had the same thought some days back, that's why i re-build the original audio input interface. So obviously that's not the reason since it happens on both constructions. > Wonder if the effect occurs at the same time on ch1 and say ch4? > Or instead the effect is independent on the effected channels. From the recent monitoring of all 6 channels (3 pairs) it looks like it is independent. So far we can say that it is just a small AM component, that's not so dramatic. Anyway i will continue to search for the reason... 73, Stefan --------------030908020308020409030102 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Paul,

thanks for the analysis and the tutorial :-)

Am 09.07.2017 07:46, schrieb Paul Nicholson:
What signal voltage does your DDS put into the Octo?
It was at 10 mV +- 0.5 mV.

What input gain is alsamixer set to?
All channels set to 49/100, this is +6.5 dB gain.

Am 08.07.2017 19:38, schrieb Paul Nicholson:
We can just see a slight change to the ch1 amplitude
which lasts about 100mS.
OK, so no loss of samples, rather an AM component. That's not so dramatic. Anyway, let's find the problem.
Likely to be an EMC effect. I will have a look on the pcb and will eventually re-solder some pins.
It would also be useful to stream CH1 and CH2 via the LAN so i can watch it into SpecLab in real time. Then i could use some cooling spray to seach for bad solder contact. Often it also helps just to touch the contacts with the finger and see for any differences. It started my radio 'carrer' that way ;-) : In 1993, when i was 17 yrs old, a friend donated me a damaged CB-transmitter. I simply touched the pcb everywhere until i found a region where the noise started to sound different. Suddenly i heared some people talking!!!!! I replaced a capacitor and it worked again...
So far i didn't manage to send a stream over the network to receive it on my windows PC in SpecLab. Maybe you have an idea? :-) I saw the notes on the vlfrx tools documentation site of course, but didn't spend enough time on that so far it seems.

Just shows a steady phase drift, we're not quite on frequency here
with this recording
This is due to my undisciplined DDS VFO.

- did it go through vttime? 
Unintentionally not. vtcard sends to a buffer @raw, vttime takes from @raw and sends to @locked. I disabled vttime for an earlier test and put vtresample to @raw instead of @locked. Forgot to correct that for the test.
But it doesn't matter for getting the glitches.

Curious.  Signal goes up, background noise drops. I wonder if
there is a dodgy input capacitor or dry joint.  Not sure about
that explanation, it would be odd to see the same on more than
one channel.
Right. I had the same thought some days back, that's why i re-build the original audio input interface. So obviously that's not the reason since it happens on both constructions.

Wonder if the effect occurs at the same time on ch1 and say ch4?
Or instead the effect is independent on the effected channels.
>From the recent monitoring of all 6 channels (3 pairs) it looks like it is independent.

So far we can say that it is just a small AM component, that's not so dramatic. Anyway i will continue to search for the reason...

73, Stefan

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