Ive been experimenting with a low power FM band TXer. See here http://electronics-diy.com/tx200.php.
I have built crystal controlled FM txer's , they wander on the band with temp changes. Apparently PPL's stay rock solid on the TX freq they are set at.
The TXer can be digitally tuned by using a digital to analogue converter under digital controll. As far as I can understand it the mcu takes a reading from the Txed signal and then adjusts the digital to analogue converter output voltage if need be to put the TXer back on the freq it should be on.
The design used in this example uses a PIC16F84 and a SAA1057. The SAA1057 data sheet is here.
www.peter-geisler.de/datasheet_SAA1057.pdf
I got to thinking it might be possible to do this sort of thing with a picaxe and a digital to analogue converter IC.
The biggest problem I can see straight off is can the picaxe count frequencies in the FM band range 88- 107 mghz. I dont see how this could be done because the picaxe isn't running at any where near that speed.
Can this be done? Any input would be appreciated.
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I have built crystal controlled FM txer's , they wander on the band with temp changes. Apparently PPL's stay rock solid on the TX freq they are set at.
The TXer can be digitally tuned by using a digital to analogue converter under digital controll. As far as I can understand it the mcu takes a reading from the Txed signal and then adjusts the digital to analogue converter output voltage if need be to put the TXer back on the freq it should be on.
The design used in this example uses a PIC16F84 and a SAA1057. The SAA1057 data sheet is here.
www.peter-geisler.de/datasheet_SAA1057.pdf
I got to thinking it might be possible to do this sort of thing with a picaxe and a digital to analogue converter IC.
The biggest problem I can see straight off is can the picaxe count frequencies in the FM band range 88- 107 mghz. I dont see how this could be done because the picaxe isn't running at any where near that speed.
Can this be done? Any input would be appreciated.
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