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<br><br>> From: awalls@radix.net<br>> To: ivtv-users@ivtvdriver.org<br>> Date: Thu, 18 Feb 2010 19:28:58 -0500<br>> Subject: Re: [ivtv-users] hvr-1600, frame CRC mismatch - incomplete frame<br>> <br>> On Thu, 2010-02-18 at 10:33 -0500, Kyle Lil wrote:<br>> > <br>> > <br>> <br>> > OK, so I built an attenuator with a potentiometer in position Z2 for<br>> > the circuit diagram you sent me. I'm sure there are probably a whole<br>> > slew of problems this could introduce (especially since I did not put<br>> > a pot in position Z1 also), but I wanted to be able to easily look at<br>> > the various attenuation levels (and I don't have a soldering iron at<br>> > home, just at work). What I found was that the glitches are still<br>> > apparent even when I turn the potentiometer to a level that make my<br>> > cable box OOB AGC go to >30% (which it now rates as "fair" instead of<br>> > "good"). The cable box and HVR-1600 are at the output of the same<br>> > splitter, which is after (downstream of) the adjustable attenuator I<br>> > built. The way I constructed the circuit, I could not provide enough<br>> > attenuation to cause the tuner to lose station lock, but with the<br>> > maximum attenuation (~-14dB from attenuator + -6dB from the two<br>> > splitters between the HVR-1600 and the wall) I could achieve, the<br>> > glitch rate was the same (or maybe slightly higher).<br>> <br>> Hmmm. Crud, io suspect there must be something else going on.<br>> <br>> My next guess is that the HVR-1600's AGC is responding too quickly (or<br>> too slowly?) to variations in the incoming signal.<br>> <br>> I'll have to think about it though.<br>> <br>> Since I have a somewhat similar condition on two ATSC stations, I'll<br>> work up a debug patch for the s5h1409 driver that reports some more<br>> stats from the CX24227. I have never used the additional statistics<br>> registers before and I don't have much faith in the documentation I<br>> have, so I'm not sure if they work or will be useful. We'll see. I<br>> won't be able to do anything until Saturday night at the earliest.<br>> <br>> <br>> <br>> > <br>> > <br>> > I will try to build an attenuator today that is able to reduce the<br>> > signal all the way down to an un-lockable level. Is it possible that<br>> > the HVR-1600 is so sensitive that a signal level my cable box rates as<br>> > only fair is still too large for it?<br>> <br>> I would doubt it, but it still could be the case.<br>> <br>> I think if we can get more stats from the CX24227 chip, we may get more<br>> insight as to what might be wrong.<br>> <br>> Regards,<br>> Andy<br>> <br>> <br>> <br>> <br>> _______________________________________________<br>> ivtv-users mailing list<br>> ivtv-users@ivtvdriver.org<br>> http://ivtvdriver.org/mailman/listinfo/ivtv-users<br><br>That sounds great, Andy. Thanks so much for spending the time to get to the bottom of this. <br><br>I built the more powerful attenuator and essentially what I see is that the error rate increases dramatically as the gain approaches zero. <br><br>Please let me know if you are able to get the CX24227 to report more statistics and have some tests you'd like me to run on my end. <br><br>Kyle<br><br><br><br> <br /><hr />Hotmail: Powerful Free email with security by Microsoft. <a href='http://clk.atdmt.com/GBL/go/201469230/direct/01/' target='_new'>Get it now.</a></body>
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