From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:54413 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752610Ab2HNLKx (ORCPT ); Tue, 14 Aug 2012 07:10:53 -0400 Received: by lbbgj3 with SMTP id gj3so163969lbb.19 for ; Tue, 14 Aug 2012 04:10:51 -0700 (PDT) Message-ID: <502A322D.2060900@iki.fi> Date: Tue, 14 Aug 2012 14:10:37 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Reinhard Nissl CC: linux-media@vger.kernel.org Subject: Re: STV0299: reading property DTV_FREQUENCY -- what am I expected to get? References: <502A1221.8020804@gmx.de> In-Reply-To: <502A1221.8020804@gmx.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 08/14/2012 11:53 AM, Reinhard Nissl wrote: > Hi, > > it seems that my 9 years old LNBs got some drift over time, as tuning > takes quite a while until I get a lock. So I thought I could compensate > this offset by adjusting VDR's diseqc.conf. > > Therefore I first hacked some logging into VDR's tuner code to read and > output the above mentioned property once it got a lock after tuning. As > VDR's EPG scanner travels over all transponders when idle, I get offset > values for all transponders and can then try to find some average offset > to put into diseqc.conf. > > So here are several "travel" results for a single transponder ordered by > Delta: > > Sat. Pol. Band Freq (MHz) Set Freq (MHz) Get Delta (MHz) > S13,0E H H 11938 11930,528 -7,472 > S13,0E H H 11938 11936,294 -1,706 > S13,0E H H 11938 11938,917 0,917 > S13,0E H H 11938 11939,158 1,158 > S13,0E H H 11938 11939,906 1,906 > S13,0E H H 11938 11939,965 1,965 > S13,0E H H 11938 11940,029 2,029 > S13,0E H H 11938 11940,032 2,032 > S13,0E H H 11938 11940,103 2,103 > S13,0E H H 11938 11940,112 2,112 > S13,0E H H 11938 11940,167 2,167 > S13,0E H H 11938 11941,736 3,736 > S13,0E H H 11938 11941,736 3,736 > S13,0E H H 11938 11941,736 3,736 > S13,0E H H 11938 11942,412 4,412 > S13,0E H H 11938 11943,604 5,604 > S13,0E H H 11938 11943,604 5,604 > S13,0E H H 11938 11943,604 5,604 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,472 7,472 > S13,0E H H 11938 11945,777 7,777 > S13,0E H H 11938 11945,777 7,777 > S13,0E H H 11938 11945,777 7,777 > S13,0E H H 11938 11945,777 7,777 > > I really wonder why Delta varies that much, and there are other > transponders in the same band which have no larger deltas then 3 MHz. > > So is it at all possible to determine LNB drift in that way? > > My other device, a STB0899, always reports the set frequency. So it > seems driver dependent whether it reports the actually locked frequency > found by the zig-zag-algorithm or just the set frequency to tune to. That is tricky part. I recently explained that too when Mauro added get_afc() callback: http://www.spinics.net/lists/linux-media/msg51308.html It should return actual frequency frontend is tuned (I am not sure about DVB-S as there is IF/LNB). But the way DVBv5 API is implemented, using cache, you never know if it is same value you set or some real value tuner is listening. You can never trust APIv5 get values - those are 1) just same you have set or 2) those could be values updated by driver. > > Thanks in advance for any replies. > > Bye. regards Antti -- http://palosaari.fi/