[mythtv-users] Scheduled recordings dropping first digit of channel number

[Michael T. Dean]

On 05/07/2007 11:11 AM, Gary wrote:
> Frequently , a  scheduled recording, records the wrong channel.
> I have Dish network satellite with the JVC satellite receiver. The
> satellite receiver is controlled by an ir-blaster connected to a serial
> port.
>
> It looks like, at times, the first digit of a three digit channel number
> it dropped. For instance, the movie is on channel 139; only the "39" is
> received by the satellite receiver; there is no channel 39 - the next
> higher available channel is 43, channel 43 is what is recorded.

I saw the exact same thing happening on my system (starting in late 
August 2006 and going through mid-November 2006).  I couldn't pinpoint 
any changes that may have caused it, and I chalked it up to hardware 
failure (i.e. I had been using the transmitter I built for over 3 years 
when it started happening).

> How can I correct this?

Probably not an ideal solution for you, but what worked for me was 
cancelling my DISH subscription and upgrading my system to an 
all-high-def-via-OTA system (i.e. no STB to control, anymore).  :)

My DISH cancellation/system upgrade had nothing to do with the channel 
change issues--I had been planning it for about a year (just needed to 
be home long enough--no work travel--to get it done).  I had made some 
time over a 4-month period for the changes (I had told myself I wouldn't 
upgrade Myth until I did a major reconfiguration of my entire network 
and every system on it, so there was a lot more than just a Myth upgrade 
involved), and about a month into the work, I started seeing the issue.  
Since I knew I was close to not needing the IR transmitter, I didn't 
look into fixing it.

All I had done was create a channel change script that used locking to 
ensure only one channel change was occurring at a time (and the locking 
was never triggered--Myth always issues channel change commands 
one-at-a-time and waits for completion) and that logged the actions so I 
could see what was happening.  The successful channel changes and 
unsuccessful channel changes looked exactly the same in the logs--i.e. 
in both situations Myth provided the right info to the script and the 
script ran the right commands.  However, IR signal "micro" timing issues 
wouldn't have shown in the logs, nor would hardware issues.

My best guess--now that I have reason to believe it wasn't my 
hardware--is that it's a timing issue with LIRC due to kernel preemption 
or IRQ's or something like that.  Any thoughts of trying a different 
transmitter, such as one with its own timing circuitry?  (Is this one? 
http://iguanaworks.net/products.psp -- I actually plan to get one of 
those, but no longer have a DISH subscription, so I won't be able to 
test it with my DISH boxes.)

If it's not that, perhaps DISH changed their software a bit making the 
IR reception a bit more finicky.  When did you start to see issues?

BTW, are you using a good lircd.conf.  I highly recommend 
http://www.mythtv.org/wiki/index.php/DISHNetworkLIRCConfiguration .  If 
you look at the page's history, you'll notice it was added to the wiki 
on 29 Oct 2006 (within the time when I was having issues), and I'm the 
one who posted it.  I had seen Endaf's post ( 
http://www.gossamer-threads.com/lists/mythtv/users/196566#196566 ) 6 
months earlier, but hadn't made time to test his codes.  After a couple 
of months of dealing with this issue, I tested the improved codes--and, 
while they didn't fix the problem, they did make it occur less 
frequently than when I was using raw codes.

HTH,
Mike