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FM Trap for car radio

I

Izwebusr

Hi Everyone:

Hi. I have the following problem: I have a universal FM Modulator Bluetooth device (Audiovox UniStreamOne) connected to my radio. It sends the audio through one of the radio stations (say 88.5 FM)

Radio details: Mercedes Alpine MF2910

As long as there is an audio Bluetooth signal going from my phone to the Bluetooth device, all is ok. But, when I pause the music, answer a call, etc. and the audio Bluetooth signal is lost, the UniStreamOne lets the tuner signal pass to the radio. This is a very loud white noise. And so, the experience is extremely annoying.

I am hoping to find something that I can connect after the UniStreamOne and before the car radio that will ALWAYS send a "blank" audio signal UNLESS the FM modulator is sending the Bluetooth audio signal. That way, the car radio will never send out the annoying white noise sound.

Alternatively, I would like to find a filter that I can connect between the antenna and the FM modulator that blocks 88.5 FM. That way, the radio will recognize the signal as white noise and reduce the amplification (it does this when there is a "station" that is completely empty).

The connector for either would have to be Volk or Motorola.

Any suggestions are very much appreciated.

Thank you,
 
Is the Interface module set to 88.7? Is your radio set to match that, or is it 1 channel off (88.5), where it picks up signal 'hash' from the 88.7 lower sideband??
 
I have a couple of those Belkin units that have the higher power before they were pulled off the market. Not Bluetooth, but they take headphone level audio. A little hacking to find the antenna out - put 31 inches of wire on it, and I can get 70 feet out of the thing. Or get it through my car to the antenna outside. I also hacked it to get the audio level correct (a little more complicated that just that, but that was the effect). The can tune any channel between 88.1 and 107.9. they sound great. Not sure if that would solve your problem, but I am sure Belkin comes up on an eBay search.

As for an 88.5 trap, you would need an impossibly high Q on your filter. I know the cable companies used to trap channels like HBO with very high Q filters, but I don't think even that approach would work with a 200 kHz FM channel.
 
Big 121 said:
Is the Interface module set to 88.7? Is your radio set to match that, or is it 1 channel off (88.5), where it picks up signal 'hash' from the 88.7 lower sideband??
Click to expand...

The Bluetooth unit and the radio are both set to 88.7. Sound is always good an clear when the phone is sending a sound signal to the Bluetooth unit (and Bluetooth unit to radio). It is only when it stops that the sound reverts to antenna and the loud white noises is sent to speakers.
 
Thanks for the suggestion. Not sure if this would work but I would like to investigate further. I am not sure what I would be looking for in Ebay. Can you please provide more information? A link, maybe?

Thanks
 
rbrucecarter5 said:
This is the model I have:

http://www.ebay.com/itm/Belkin-Tune...-for-All-iPod-iPhone-MP3-Player-/250952196155
Click to expand...

Thank you for this info but I doubt this will solve the problem. It is essentially the same thing I have but the signal from the Belkin to the radio is wireless (vs. wired with the one I have). This means that the sound quality will probably be slightly worse and I will not eliminate the annoying white noise from the radio when there is no signal from the iPhone.

Thanks anyway
 
Izwebusr said:
Thank you for this info but I doubt this will solve the problem. It is essentially the same thing I have but the signal from the Belkin to the radio is wireless (vs. wired with the one I have). This means that the sound quality will probably be slightly worse and I will not eliminate the annoying white noise from the radio when there is no signal from the iPhone.

Thanks anyway
Click to expand...

So, here's how I solved the "white noise" issue in my truck, and as long as your cigarette lighter(12v) turns off power with the ignition, you will be golden. Go to Fry's, Best Buy, Radio Shack, or wherever (Even Family Dollar and Dollar General sell them now), and pick you up a pocket sized FM transmitter. It is Part 15 compliant, and when you turn on the ignition of your vehicle, the transmitter will come to life with the cigarette lighter, covering up any white noise with a dead carrier. Even if your cigarette lighter has power to it after the ignition is shut off, thus leaving the transmitter powered up, it really drains no more from your battery than your digital clock that keeps time even with the ignition off.

I guarantee you will be satisfied with the results. No more turning on the ignition, after having forgotten you last drove with the volume cranked way up, and being scared out of your skin when the static of an unused frequency blasts through your speakers. The units range from the cheapos around $10, to the more elaborate ones ranging in the $50-75 range. Most now come with a handy remote, which is just one more thing to keep track of...
 
purpledevil said:
So, here's how I solved the "white noise" issue in my truck, and as long as your cigarette lighter(12v) turns off power with the ignition, you will be golden. Go to Fry's, Best Buy, Radio Shack, or wherever (Even Family Dollar and Dollar General sell them now), and pick you up a pocket sized FM transmitter. It is Part 15 compliant, and when you turn on the ignition of your vehicle, the transmitter will come to life with the cigarette lighter, covering up any white noise with a dead carrier. Even if your cigarette lighter has power to it after the ignition is shut off, thus leaving the transmitter powered up, it really drains no more from your battery than your digital clock that keeps time even with the ignition off.

I guarantee you will be satisfied with the results. No more turning on the ignition, after having forgotten you last drove with the volume cranked way up, and being scared out of your skin when the static of an unused frequency blasts through your speakers. The units range from the cheapos around $10, to the more elaborate ones ranging in the $50-75 range. Most now come with a handy remote, which is just one more thing to keep track of...
Click to expand...

That sounds like it might work. Will give it a try. Thanks.
 
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