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Wireless Voice Transmitter — Parallax Forums

Wireless Voice Transmitter

Dan TaylorDan Taylor Posts: 207
edited 2009-06-11 02:13 in Propeller 1
How can you transmit the voice detected from the microphone through the RF Transmitter and receiver sold by parallax and then outputted by a speaker.
By using the Microphone to Headphones all you would need is the RF link. Is this possible? I have never used the RF transmitters before with the propeller, so please help!
Thanks!

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Dan Taylor

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-06-10 23:49
    It's possible, but not as simple as you might think. The maximum Baud for the transmitter/receiver combination is around 20,000. That's not enough to transmit more than around 1KHz using 8 bit samples. There are other forms of encoding and compression that can increase the maximum frequency. You're still not going to get much of an improvement. For voice, you only need a maximum frequency of 3KHz for good intellegibility.
  • RaymanRayman Posts: 14,833
    edited 2009-06-11 00:09
    In principle, I think you could use the TV driver to generate video with your audio on VHF CH3 and then use a radio with VHF to receive it...

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    My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-06-11 00:31
    What kind of range are we talking about, Rayman?
  • localrogerlocalroger Posts: 3,452
    edited 2009-06-11 00:40
    It should be possible for the prop to generate a carrier wave at any frequency where the counter PLL's are stable and frequency modulate it simply by adjusting the counter parameters. My docs and stuff are 1,500 miles away right now but IIRC the FM broadcast band should be right in the sweet spot for that kind of thing.

    Of course there are also all-analog solutions for this, in the USD$40 range in kit form. I assume the OP wants to do something else with the voice before transmitting it?
  • RvnPhnxRvnPhnx Posts: 36
    edited 2009-06-11 02:13
    I've been thinking about using a prop to tx/rx audio, but I wasn't planning on doing so for the purpose of voice. It seems to me that the direct modulation of an RF PLL should be possible, and it looks at least possible to do pseudo-direct detect of audio. But, to be frank, if you're looking to move voice around and not looking to do something like build a TNC then you might as well just use an FM MOD/DEMOD PLL and save yourself some fairly large headaches.

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    --RvnPhnx
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