Author Topic: V-FMT212 noise on and off  (Read 7832 times)

Offline modderhut

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V-FMT212 noise on and off
« on: December 11, 2014, 02:41:54 PM »
My V-FMT212 FM gold transmitter connected to Pi with powered USB hub runs fine for half a song and the produces a lot of distorted noise. You can just hear the song in the noise but it's really bad After a few minutes it's fine again for a few minutes. Settings on transmitter are default except for enabling RDS and frequency. Tried a bunch of different frequencies and different settings.

Anyone seen this too or as a pointer on how to trouble shoot? Quite lost on this one.

Thanks !

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #1 on: December 11, 2014, 09:00:17 PM »
Unfortunately this is a known issue.

Currently your options are:
1. Run the Vast in stand-alone without RDS.  This will require you to power it via a USB charger (not connected to a computer) and use the audio jack.  You can do this because you have the gold version.

2. Run an "unsupported" configuration, which is what I'm currently doing.  This involves rolling back the kernel, and giving the USB-audio driver a special parameter.  This is how I'm running my show this year, and it's 95% better than the way it runs on our current v1.0 image, although there are still audio glitches from time to time.  This method will not work if you're using a B+ revision of the Pi.

If you're interested in #2, let me know if you'd rather have a script to enable/disable the unsupported configuration, or if you're OK running a couple commands from an SSH session.

You can read about this here:
http://falconchristmas.com/forum/index.php/topic,1503.15.html
http://falconchristmas.com/forum/index.php/topic,1562.0.html
https://github.com/raspberrypi/linux/issues/575

I tried a newer kernel (3.14 version) based on the reports from bug 575 linked above, but still experienced the "robot" audio you're experiencing.  It seems people are using other USB audio devices successfully on their Pis, so I presume there is something specific about the Vast that is causing this problem.  I need to do more research on sample rates, and how they interact with the kernel, but since I have a 95% working solution, I'm not looking into it until next year.

Offline modderhut

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Re: V-FMT212 noise on and off
« Reply #2 on: December 12, 2014, 08:37:27 AM »
thank you for your answer much appreciated! Saves me lot of "what I'm I missing" headaches.  I have 2x B+ so your second option is not a valid one for me. I'll get a male/male audio jack tomorrow.

If you need a tester in the future for the B+ let me know, happy to help, pretty much a linux NOOB but an IT pro so have some knowledge and can work with Putty.

Thanks for this amazing piece of Pi firmware, this little Pi runs it all (almost) flawless while my dual-core laptop was struggling last year.

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #3 on: December 12, 2014, 09:57:04 AM »
I'll definitely keep you in mind next year when I start digging more into what is required in updated kernels to get this silly thing working the way it should.  Thanks for the offer to help!

Offline modderhut

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Re: V-FMT212 noise on and off
« Reply #4 on: December 12, 2014, 10:17:17 AM »
NP

just read the link you send and this is indeed exactly the problem I'm having. I can also solve it by hitting volume up or down, one click fix.

Frostyritz  fixed it by; "SudoMac:tmp sudoritz$ while true ; do links -dump http://192.168.1.160/fppxml.php?command=setVolume"&"volume=45 ; sleep 2 ;  links -dump http://192.168.1.160/fppxml.php?command=setVolume"&"volume=55 ; sleep 2 ; done"

I have no idea how to implement that, can anyone give me a quick instruction? looks like its cmd running from a mac. This should be possible from cron on the Pi also right?

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #5 on: December 12, 2014, 11:14:15 AM »
I'm guessing his "SudoMac:tmp sudoritz" is some sort of copy/paste stuff.  The rest is just a basic bash 1-liner type thing.  links isn't available on the Pi, but this can be done slightly differently:

Code: [Select]
#!/bin/bash

if [ "x$1" == "xpreStart" ]; then
        (
                while true; do
                        wget -o/dev/null -O/dev/null "http://localhost/fppxml.php?command=setVolume&volume=55"
                        sleep 2
                        wget -o/dev/null -O/dev/null "http://localhost/fppxml.php?command=setVolume&volume=54"
                        sleep 2
                done
        ) &
elif [ "x$1" == "xpostStop" ]; then
        kill $(ps aux | grep preStart | grep -v grep | awk '{print $2}') &>/dev/null
fi

Copy/paste that into a file called "UserCallbackHook.sh" and upload it to the Pi using the file manager.   Make sure it has unix line endings, or the script won't work properly, and it needs to have the exact capitalization in the file name as well.  This will create a backgrounded process to change between 55 and 54 every couple seconds.  When FPPD starts, it will start this, and when FPPD stops, it should kill it.

Offline modderhut

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Re: V-FMT212 noise on and off
« Reply #6 on: December 12, 2014, 05:52:40 PM »

The script does its job, I see the volume on the status page change when I refresh.  Show not running anymore, I'll test and update tomorrow.

Offline modderhut

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Re: V-FMT212 noise on and off
« Reply #7 on: December 13, 2014, 06:26:22 AM »
That works perfectly!! the moment the noise kicks in it gone within a beat.

Thanks again, you really saved the day for me!!  I'll copy your answer to DIYC where I had posted the same question so others can benefit from it too.

Offline steelth

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Re: V-FMT212 noise on and off
« Reply #8 on: January 29, 2015, 05:53:50 PM »
where in the "UserCallbackHook.sh" file do you insert the code?

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #9 on: January 29, 2015, 06:22:51 PM »
Sorry my original post wasn't more clear.  You will need to create a new file called "UserCallbackHook.sh" and upload it to your pi's "Scripts" directory of your USB stick.

Offline steelth

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Re: V-FMT212 noise on and off
« Reply #10 on: January 29, 2015, 11:19:54 PM »
OK got it thanks. Worked like a charm.  I can't tell you how many hours I spent before my Halloween show last year trying to figure the issue out.  After 2 months off it's time to start preparing for next Halloween.
Thanks again.

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #11 on: January 30, 2015, 08:03:27 AM »
I'm hoping by next year I can get a working kernel configuration that doesn't have the noise problems and this won't be needed.

Offline robskimeister

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Re: V-FMT212 noise on and off
« Reply #12 on: October 31, 2015, 09:01:45 AM »
I know this is an old topic, but I think it's still relevant due to the Vast FMT212 issues in FPP and the need for this script.

I had a bit of a problem getting the script to run because of this requirement that was mentioned above:
Quote
Make sure it has unix line endings, or the script won't work properly

Maybe I'm just a noob, but I had  no idea how to do this and there was no mention of how to do it.  I tried saving the file in notepad, but it didn't work.  So I figured I'd post the solution that I finally found.  There may be a simpler way, but this is fairly simple & it worked:

I created a new document in NOTEPAD++ (an awesome free file editor you can download online).  Then go to Edit > EOL Conversion > UNIX Format.  Then paste the script from Materdaddy from the earlier post & save using the EXACT filename specified in the posts above (UserCallbackHook.sh). 
FYI:  I found this info here:  http://wiki.secondlife.com/wiki/How_to_avoid_DOS_line_endings_in_Windows_tools

This worked for me.  Now when I go to the FPP status screen I can see the volume has been set to 54 or 55 by the script.  Cool!

Hopefully this will help others who run into this issue.
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Offline lrhorer

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Re: V-FMT212 noise on and off
« Reply #13 on: December 12, 2015, 08:09:50 AM »
It's not working, here.  That is to say it looks like it is resetting the volume, but that does not seem to prevent or reduce the issue.  It still happens for several seconds at random intervals.  Is there something magic about the numbers 54 and 55?  That volume is rather too low for my purposes, so I changed the numbers to 94 and 95.

Offline Materdaddy

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Re: V-FMT212 noise on and off
« Reply #14 on: December 14, 2015, 10:12:39 PM »
AFAIK there was nothing special about the numbers.  It has worked for many people, but due to the issue I moved from a Pi to a BBB and haven't looked back.

Unfortunately there won't be any activity on this issue unless I hear back from the Pi kernel developers on the ticket here: https://github.com/raspberrypi/linux/issues/1145

I plan to revisit this after the holiday season with hopes for a fix next year, but based on the fact that the problem only happens with the Vast and the Pi (change either one and the problem goes away) I'm less inclined to keep digging.  The recommendation will be to change to BBB or use the analog input to the Vast and lose RDS capabilities.

Sorry to be the bearer of bad news!

 

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