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-   -   N900 Radio Transmitter: ways to amplify the radio signal (https://talk.maemo.org/showthread.php?t=38582)

Laughing Man 2009-12-27 23:59

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
Quote:

Originally Posted by msa (Post 443345)
maybe its important how the n900 is faced toward the antenna? :>
maybe it transmits the signal in a focussed direction rather than broadcasting it 360 degrees, so if its not pointing to the antenna the right way, you'll have bad reception.

just a thought though, still dont have a n900 to prove this theory to myself.

That's an interesting theory, I just tested it myself with the stereo in my room.

I first walked the farthest before I heard static. (pretty much out of the room, the stereo is on the opposite end). Car length wise it'd be about 1.5 Toyota Camrys (yes I know a odd measurement) length.

When the N900's screen is facing the user, and the back is facing the stereo the signal was clearer (no static). If I flipped the N900 around so the back was facing me and the screen was facing the stereo then I could hear static.

Though having tested the transmitter in a car being in a metal car does reduce its range a bit. I've had trouble getting it to work without static even when say resting on the middle compartment (between the two front seats). Toyota cars have their receivers in the back of the car.

Edit: And if you get in the way of the signal there's static too. E.g. position the N900 between you and the radio receiver.

I live in the USA (for clarification's sake). So whatever regulations for transmissions come from the FCC.

Bratag 2009-12-28 01:16

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
89.1 - N900 placed on the drive side dash and pushed back to meet the windshield.

romanianusa 2009-12-28 01:27

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
Yea i got to admit...transmission is not that great and i always get static signal along with the music. I didn't bother to fine tune it though as i was busy driving. But from my first experience...that's what's what happened.

smage 2009-12-28 03:27

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
ok

when im using the stereo in my home the signal is lost if i hold the n900 more than 10cms awasy from the antenna in any direction.

by signal loss i mean a complete loss and not just simple noise that happens at 5 cm

timwatt 2009-12-28 03:34

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
I can confirm I can get it to work, but I need to be +-50cm from the antena. I find the relative volume to be soft, magnifing the static because I have the volume so high.

EmmaGx 2009-12-28 11:43

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
Quote:

Originally Posted by Thor (Post 443327)
Which frequencies have you tried?
I think the trick may be to find an "empty" frequency, if such a thing is possible in the UK.

I've generally stuck to 88.1 ... although I did try it on a higher frequency on a radio that didn't go down that far ... any suggestions for a good frequency for Bristol in the UK?

go1dfish 2009-12-28 21:25

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
Found this today: https://bugs.maemo.org/show_bug.cgi?id=6792#c9

When FM transmitter is on, the following sys file is present:

/sys/class/i2c-adapter/i2c-2/2-0063/power_level

You might could try fiddling with this value and see what happens. Of course you do so at your own risk and I take no responsibility for you frying device or getting frog-walked/fined by the FCC.

Also would be curious to know what the value in this file is for different people:

With fm transmitter on do (this will not change anything, it's just a way to see what the current level is):

Code:

cat /sys/class/i2c-adapter/i2c-2/2-0063/power_level
And report back what number comes back, I get 112 (also the number referenced in that bug report)

go1dfish 2009-12-28 21:28

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
Quote:

Originally Posted by Laughing Man (Post 443367)
When the N900's screen is facing the user, and the back is facing the stereo the signal was clearer (no static). If I flipped the N900 around so the back was facing me and the screen was facing the stereo then I could hear static.

This meshes with my experience in a Rental with a top roof antenna.

I only got a decent signal by clipping the n900 to the headliner in my e51 case, and signal was better with screen down instead of screen up.

That One Guy 2009-12-28 21:31

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
I finally tried the FM transmitter.

1. 2003 F250 Truck - Pretty good
2. 2008 F450 Truck - Kinda crappy
3. 05 and 08 CL65's - Couldn't hear anything playing.

This leads me to believe that different cars have different RF insulator qualities for the antenna cable going into the head unit.

mysticrokks 2009-12-28 21:31

Re: N900 Radio Transmitter: ways to amplify the radio signal
 
i have had fm transmitters that transmit at 87.9(and a car with the pick up ability for 87.9)- and it wqas great..

i cannot find any really good signal in london.. best is 154.1

its not great.


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