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: : mailn 1480; 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 v69BP0qV003299 for ; Sun, 9 Jul 2017 13:25:01 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dUAGp-0007Ia-GU for rs_out_1@blacksheep.org; Sun, 09 Jul 2017 12:20:59 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dUAGo-0007IR-Ie for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 12:20:58 +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 1dUAGl-0008Vu-Qq for rsgb_lf_group@blacksheep.org; Sun, 09 Jul 2017 12:20:57 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 532B620FA1 for ; Sun, 9 Jul 2017 13:20:54 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3x55W95sVxz10HW for ; Sun, 9 Jul 2017 13:20:53 +0200 (CEST) Message-ID: <59621195.4080109@posteo.de> Date: Sun, 09 Jul 2017 13:20:53 +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: <15d26b31fb5-c01-17d82@webjas-vab174.srv.aolmail.net> In-Reply-To: <15d26b31fb5-c01-17d82@webjas-vab174.srv.aolmail.net> X-Scan-Signature: 622b0ca3461797caf37867321c193763 Subject: Re: LF: Octo-soundcard for the Raspi, another question Content-Type: multipart/alternative; boundary="------------040006010600010702010903" 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: 12204 This is a multi-part message in MIME format. --------------040006010600010702010903 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hello Markus, Am 09.07.2017 11:34, schrieb Markus Vester: > First I thought it might be flicker noise on the ADC reference voltage > but why should it affect only three of six channels? Right. > With USB soundcards, the data packets are usually sent with 1 ms > repeat rate, and we have sometimes seen an artifact consisting of weak > 1 kHz spaced spectral lines. I do not know about the transfer protocol > of the Octo soundcard which is connected to the RasPi interface > pins. In case the packets are organized similarly, we might experience > the same problem, so 1 kHz or 0.5 kHz might have been just an unlucky > choice for the test signal frequency. Perhaps you could try again at > some odd frequency? That's a good point. > Also a test at higher amplitude (e.g. -20 dB FS) would tell us whether > it is a multiplicative (ADC scaling) or additive (EMC) error.. I will use different signal levels and will report in a separate email. > The warm summer is not a good time to bury oneself in the shack ;-) Warm? It is HOT!!! I can't stay outside in the sun during the midday time. The sun is out for 16 hours per day now, so i can easily afford to spend 4...6 hours in the shack/office in the midday time. Yesterday i have been on the tree until 21:20 local time. A great pleasure. BTW it was the 95th time that i climbed the tree :-) I shut down the Raspi to take a clone of the SD card. No i think about installing vlfrx tools there, remotely, while sitting in the cool office :-) 73, Stefan --------------040006010600010702010903 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Hello Markus,

Am 09.07.2017 11:34, schrieb Markus Vester:
First I thought it might be flicker noise on the ADC reference voltage but why should it affect only three of six channels?
Right.
 With USB soundcards, the data packets are usually sent with 1 ms repeat rate, and we have sometimes seen an artifact consisting of weak 1 kHz spaced spectral lines. I do not know about the transfer protocol of the Octo soundcard which is connected to the RasPi interface pins. In case the packets are organized similarly, we might experience the same problem, so 1 kHz or 0.5 kHz might have been just an unlucky choice for the test signal frequency. Perhaps you could try again at some odd frequency?
That's a good point.
Also a test at higher amplitude (e.g. -20 dB FS) would tell us whether it is a multiplicative (ADC scaling) or additive (EMC) error..
I will use different signal levels and will report in a separate email.
The warm summer is not a good time to bury oneself in the shack ;-)
Warm? It is HOT!!! I can't stay outside in the sun during the midday time. The sun is out for 16 hours per day now, so i can easily afford to spend 4...6 hours in the shack/office in the midday time. Yesterday i have been on the tree until 21:20 local time. A great pleasure. BTW it was the 95th time that i climbed the tree :-)
I shut down the Raspi to take a clone of the SD card. No i think about installing vlfrx tools there, remotely, while sitting in the cool office :-)

73, Stefan
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