Author Topic: FM transmitter  (Read 1217 times)

Offline PittFan

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FM transmitter
« on: October 04, 2015, 07:00:54 PM »
For the last few years, I have not really liked the quality or distance of transmission of my HLLY FM transmitter.  My antenna is a 1/4 wave ground plane.  I measured out the lengths of the antenna based on my FM transmitting frequency.
Last year (and this year) I used FPP on my Pi.  The sound was full of static and it seemed to barely transmit from the home to the road (not more than 100').
I had my transmitter in the same "box" as my Ether Dongle and a power strip.  I will not (at least plan not to) use the Ether Dongle this year, choosing the FPD.

This year in an effort to improve the issue I was thinking of a different transmitter.  However, before I do this, I was wondering if the sound from the Pi could be bad or if there is "noise" created by the other electronics in the box with the transmitter.  I tested the transmitter alone using only the output from my mobile phone and the transmitter seems to work quite well.  So this leaves me with the Pi or the interference concern.  The Pi is easy enough to check but before I do anything to test, what do others have to say about potential interference causing my problem?  Simply separating the transmitter from the other hardware would save me some money if that was indeed a potential issue.  Or might the Pi be the issue? (I think not as, I can't figure out how it would decrease the distance of transmission (as for distance, I'm not looking for more than 100'; I didn't get that much last year, the visitors needed to be quite close and in a particular location to hear anything decent).

Offline onetmat

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Re: FM transmitter
« Reply #1 on: October 05, 2015, 08:29:55 AM »
I use a SainSonic AX-05B which is similar but not very high power. Everything was in the same container (1'x2' box) as well which caused several problems. Even the lower power transmitter knocked out the wifi signal to the Pi, FM transmission distance was reduce, and static was noticeable at the lower range. I got a 6' extension cable for the headphone jack connection to the Pi to add some separation. I can drive half way around my neighborhood with no static now. I might even drop the power transmission to reduce the range a bit. I ran a cat5 to the pi this year so not sure about the wifi issue but I'm sure that's gone as well.

It's worth giving it a try. The extension cable was very cheap on Amazon.
« Last Edit: October 05, 2015, 08:42:12 AM by onetmat »

Offline PittFan

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Re: FM transmitter
« Reply #2 on: October 05, 2015, 04:22:52 PM »
Thanks!

 

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