Does anyone else have an issue with their N900 where the FM transmitter turns itself off after about a minute of silence?

If I switch the fm transmitter off and then dont play any sounds I find after aproximatly a minute the FM transmitter magically turns itself off. This is a real pain when I use the GPS software since there are often long pauses between voice prompts.

If I use the media player to play music then the transmitter stays on, it just seems like if it is not used for long enough then it simply switches itself off. Having to alunch the media player every time I want to use the gps is a bit of a pain!

Does it not turn itself back on once a new command is spoken?

Mine will switch off and then turn back on again when any sound is played.

Which GPS softwaredo you use?

Hmmmm, Yes I have sometimes noticed it does switch itself back on but that is still a bit crappy simply because as soon as it goes off the radio plays static.

Driving down the road listening to static is a sure fire way to make oneself crazy!

Also when it switches itself back on the power level is now 113 and not 118 so it is still very staticy

You know sometimes the manufacturer just trys to make things too clever. I turned the FM transmitter on and I expect it on, not sometimes on!

In some countries regulations forbid broadcasting "dead air" as an unproductive use of the frequency. The N900 transmitter as well as others like it will shut down automagically if nothing is broadcast. You should also hear a repeating beep until it does.

The manufacturer is not being clever. Just trying to abide.

Fair enough but in my country this is not illegal and the N900 as we know abides very much below the maximum transmit power level.

So does anyone know a way to force the FM transmitter to stay on?

You can try hex editing the binary like this fellow did >> http://jacekowski.org/Maemo/FMTXD

or,

Record a long MP3 of silence and run the media player and your GPS will interrupt it when giving voice guidance.

or,

Produce or find an internet radio station that broadcasts dead air and have media player connect to that instead.

(I don't know if the connection time out can be modified but if it can, a bogus radio IP address will do the trick because the transmitter stays connected while it is finding the station.)

I have found a simple brute force wayaround:
1. start fm transmitter using the GUI
2. before it timeouts, enter in a root shell:
killall -kill fmtxd
echo 0 > /sys/class/i2c-adapter/i2c-2/2-0063/tone_deviation
(script with a clickable icon can be made for this)
Now it will not stop transmitting while the navigation is quiet,
also regardless of charger pluggin in or not.
The disadvantage is of course that control of the transmitter does not work,
you have to again start it from the setup menu (even if you intend to switch it off).
Later I found out that the nokia media player also gets confused if fmtxd is not running and switches the transmitter off.


I have also looked at the kernel code in drivers/media/radio/si4713.c;
it seems that turning the transmitter on/off is done by a v4l2
muting ioctl, probably on /dev/radio0. However, since the brute force hack worked, I did not try more.

The whole process of getting the improved navigation up and running was not really straightforward, so I have gathered
the necessary information in a minihowto http://www.pittnerovi.com/jiri/hobby...900/index.html

Jiri Pittner