Need help configuring channels to work with blaster (1 Viewer)

[js016f]

I'm trying to set up the channels to work with the TV3 blaster. I have a USB-UIRT connected to a set top box that only outputs coax. I have IRSS set up, everything is set up to blast channels correctly when I test from the External Channel Changing screen, but when I try to preview an actual channel I get a Preview Failed: No Signal Detected error.

Based on what I read in another thread, it sounds like the channel number should be the same on both the Edit Channel screen and the Tuning Detail screen, and then the frequency needs to be set to the correct frequency for the channel that the stb outputs (which is channel 4). So I tuned to channel 4 (which does work) and checked the TVService.log, and updated all the channels to use 67.25 as the frequency. However even after restarting the server, I still can't tune any channel besides 4. I checked the log again, and I see two lines that show the correct frequency
card: user: setuptv:3:-1 tune tv:WTIC (FOX) Freq:67250000 Channel:9 Country:United States
analog: Tune:tv:WTIC (FOX) Freq:67250000 Channel:9 Country:United States Tuner:Cable
then the TV3 Blaster Plugin successfully blasts the channel to the stb, but then
Analog: Tuned to country:1 video:186000000 Hz audio:190500000 Hz locked:False

So it looks to me like the tv server is ignoring the frequency I told it to use and is instead using the frequency associated with the channel number.

 

[mm1352000]

Hello and welcome!

You've done really well to get to this point. Blaster setups certainly aren't easy.

My guess is that you're running a 64 bit version of Windows, and therefore you're getting hit by this known bug:
https://issues.team-mediaportal.com/browse/MP1-2959

To work around this you will need to modify the channel-to-frequency lookup table in the Windows registry. Attached is a registry update script that makes the required modifications, according to the details provided by Microsoft -->here<--. The script creates overrides for channels 1 through 999 that will cause the tuner to tune to 67.25 MHz (ie. channel 4, which is what you said the output channel for the set top box is) instead of the normal frequency.

To apply the registry script: unzip it, then right click on the "Fix Frequency Overrides.reg" file and click "merge". You'll need to do that with administrative privileges, so expect a user account control dialog to popup and ask your permission to run the script.

Note: I always recommend extreme caution when applying registry changes. This script should only make the change described above, however despite my best intentions it is always possible that I have made mistakes (...because I'm human!). For that reason I encourage you to check the script for yourself (*.reg files can be opened in any text editor - notepad, wordpad etc.). Ultimately it is your choice as to whether you decide to run the script or not. I will not take responsibility for the possible consequences of that choice, but I will be here to assist if something goes wrong.


For anybody else that's reading this thread in future...
In case it wasn't clear, if your set top box RF/coax output does not use channel 4 then this script will not work for you. Let me know and I'll be happy to provide scripts for other channel numbers.

 

[js016f]

Short answer, that worked! All channels now tune properly!

Long answer, I'm not using 64 bit. I'm running 32 bit Windows 7. I looked at the reg path and compared it to the existing keys. There were only keys for 3 channels, the three I had used for testing. And the frequency was correct.
This leads me to suspect that MediaPortal checks the registry for the frequency, uses the default for that channel if the key isn't there, tries to tune the channel, and only then does it write the frequency specified in tuning details to the registry. So the first time you try to tune the channel it will fail, but if I had tried previewing a channel more than once it would have worked, maybe.
I'd test my theory but at this point I'm so glad it worked I don't want to mess around and break it again.

 

[mm1352000]

Hmmm, interesting.

On 32 bit Windows TV Server certainly creates the appropriate registry keys before tuning when both a frequency and channel number are specified in the tuning detail. However when we actually tune, we can only pass in a channel number. We have to rely on a Microsoft component to convert the channel number to a frequency, which includes using the frequency specified in the registry if it exists.

In other words: I'm not sure why it didn't work first time.

Nevertheless, I'm glad the script helped and you're up and running. Don't hesitate to ask if you have any further questions.