Return-Path: Received: (qmail 97951 invoked from network); 11 Dec 2004 13:43:57 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore02.plus.net with SMTP; 11 Dec 2004 13:43:57 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1Cd7s1-0007n2-63 for dave@picks.force9.co.uk; Sat, 11 Dec 2004 14:05:14 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1Cd7s1-0007mz-3P for dave@picks.force9.co.uk; Sat, 11 Dec 2004 14:05:13 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1Cd7XQ-000K3w-Eo for dave@picks.force9.co.uk; Sat, 11 Dec 2004 13:43:56 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Cd7X2-0002M7-08 for rs_out_1@blacksheep.org; Sat, 11 Dec 2004 13:43:32 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Cd7X1-0002Ly-Hf for rsgb_lf_group@blacksheep.org; Sat, 11 Dec 2004 13:43:31 +0000 Received: from one.surfree.co.uk ([195.80.0.234]) by relay.thorcom.net with esmtp (Exim 4.41) id 1Cd7Wx-0007sX-LK for rsgb_lf_group@blacksheep.org; Sat, 11 Dec 2004 13:43:31 +0000 Received: from [212.248.140.30] ([212.248.140.30]) by one.surfree.co.uk (8.9.3/8.9.3) with ESMTP id OAA14609 for ; Sat, 11 Dec 2004 14:38:55 GMT Received: from 127.0.0.1 (AVG SMTP 7.0.296 [265.5.0]); Sat, 11 Dec 2004 13:43:37 +0000 Message-ID: <001001c4df87$6ab76780$045bfea9@d4f8d8> From: "Andy Talbot" To: rsgb_lf_group@blacksheep.org References: <82.1d33c60e.2eec2207@aol.com> Date: Sat, 11 Dec 2004 13:43:37 -0000 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Mime-Version: 1.0 X-SPF-Result: relay.thorcom.net: 195.80.0.234 is neither permitted nor denied by domain of southsurf.com X-Spam-Score: 0.7 (/) X-Spam-Report: autolearn=no,HTML_20_30=0.474,HTML_MESSAGE=0.001,RCVD_IN_SORBS=0.1,TW_QE=0.077 Subject: LF: Re: Frequency errors on PSK31 Content-Type: multipart/mixed; boundary="------------050006030300080800090809" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE autolearn=no version=2.63 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) This is a multi-part message in MIME format. --------------050006030300080800090809 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 8bit

As PSK31 uses differential coding, it is the phase change over the 32ms signalling period due to freqeuncy error that is important. If for BPSK, we need to maintain the phase to less than 90 degrees to remove the ambiguity, so 90/360 / 32ms = 7.8Hz freq error permissible.

For noisy signals, the determination of correct phase becomes worse, so error rate will progressively worsen with tuning error.

Andy G4JNT

----- Original Message -----

From: G0MRF@aol.com

To: rsgb_lf_group@blacksheep.org

Sent: Saturday, December 11, 2004 10:12 AM

Subject: LF: Frequency errors on PSK31

Hello.

I'm trying to produce a small PSK31 beacon on a PIC chip using one port (and an XOR gate) to initiate phase change, and others to control the mark space ratio for driving a class D amplifier for the amplitude change.

Question:

With the currently available soundcard decoders, what frequency errors are permissable in the PSK31 waveform which will still decode successfully? Normally 32ms but what tolerance is OK?

Do the decoders lock, and then suddenly lose all decoding ability if the frequency is too far off, or do they just slowly increase their bit error rate with frequency error?

73

David

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