Radio Transmitters - How to

Discussion in 'Music, Playlists & Broadcasting' started by fasteddy, Jun 7, 2010.

  1. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    OK, so you have worked out your Christmas lights and show for the year but are wondering how do i get that music out there to the cars driving past.
    It is fairly simple to do this by using a radio transmitter that is connected to the computer and following a few simple steps.

    What radio transmitter should I use?

    There are several different radio transmitters out there that can be used but be mindful that having a transmitter with to much power may be breaking the FCC regulations. Transmitter output is rated in watts and you don't need a big high powered transmitter to send out that music. I my self only use a 10MilliWatt output transmitter but coupled with a home made aerial located on the roof, my transmission range is approximately 1 km which is more than enough range for the purpose it is used for. I would reccommend staying away from the all house transmitters that you see advertised on the LOR site or at other vendors as their range and channel selection is limited and may cause disappointment.

    The transmitter i use is an EDM transmitter which can be bought from here http://www.edmdesign.com/orders.html These come in a basic kit form but the amount of soldering is very basic, pretty much solder the power leads was all that was required. The performance of these transmitters for the price can not be beaten. I'm sure others will pipe in about the Ramsey models and others but i have no experience with those and from my research when looking for a transmitter the EDM was the best value by far with great specifications.

    What aerial should I use?

    The EDM transmitters will come with a little single wire as an aerial, this is OK to use but it will not get the best out of the unit as one of the important factors in transmission is the aerial. For me i built a very simple J-pole aerial out of old 1/2 inch hard drawn plumbing copper pipe, which increased the range from about 200 metres to a kilometre. It will also help ensuring that the signal received from the cars watching is strong enough to give a good quality stereo sound as the signal will deteriorate and be received as a mono signal if the reception is weak.

    So you could either buy an external aerial, use the wire aerial that is supplied by EDM or you could build your own aerial. You can find a wealth of info on how to do this here http://www.dxzone.com/catalog/Antennas/J-Pole/
    There is also a great informative PDF on the subject (attached to this forum post below)

    Setting up the transmitter

    Now once you have the radio transmitter all ready to use, you now need to find a clear channel that will not interfere with any other channels, this is fairly simple but sometimes what appears to be a clear channel isn't and then you may find that your reception has interference, if this is the case try some different frequencies.

    The output of your transmitter will not be the exact volume intensity as a normal radio station as they uses compression algorithms to increase their range and quality. What you will find is your volume is a little lower but this should not be an issue. If your volume levels are too high then you will see clipping of the signal and distortion so there is a fine line between over doing it and under doing it.
    You can also improve your transmission quality by adjusting the attenuation on the transmitter depending if your using the lower end or the higher end of the frequency range. EDM supplies instructions on doing this as it is normally a pot to adjust but newer models can be adjusted through the display.
    Once you feel happy with your setup, test the reception with a few different radios as each cars ability to receive will vary so you may have a modern car that has great reception, but an older car with an older radio may only pick up as poor quality reception.

    Making people aware of the frequency to tune to

    Now that you have it going and tested and the frequency selected you now will need to make a clear big sign to tell everyone what channel to tune into. Several signs may be needed, one of the things I have noticed is that people are busy looking at the lights flashing and don't understand that it is synchronised to music and that they can tune their car radios into the music. Several times i saw people enjoying the lights completely oblivious to the fact that is is done to music, eventually word of mouth will fix that for most people.

    I know there are other transmitters and aerials that can be used and hopefully these users will post their experiences here as well.
     

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    fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Here is a picture of my J-pole I built which has been up since early November 2009
    Fasteddys Jpole.png

    Here is my Transmitter (EDM-TX-10P)
    EDM Transmitter.png

    Now this is being superseded by the EDM-LCD-CS-EP or you can the higher spec transmitter EDM-TX-LCD-EP which i intend to eventually upgrade to.
     

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