<x-flowed>Dan
  I used 49Mhz FM vox walkie talkies some years ago to xmit & rcv simplex
data. The problems I encountered  were impedance matching the mic and
speaker ports to the other circuitry. Data was xmitted about 10 kHz due to
the audio nature of the walkie talkies. Just a thought, regards, Mark

>From: Dan Mulally <dtcon@RAPIDNET.COM>
>Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: Advice needed  ==>PIC to PIC wireless transmission
>Date: Sat, 27 May 2000 00:25:52 -0600
>
>----- Original Message -----
>From: "Gerard Mantoux" <Gerard.Mantoux@BULL.NET>
>To: <PICLIST@MITVMA.MIT.EDU>
>Sent: Tuesday, May 23, 2000 2:02 AM
>Subject: Advice needed ==>PIC to PIC wireless transmission
>
>
> > Hello, dear PICListers,
> > I need advices, concerning one way wireless transmission of data between
>two PIC
> > 16F84 (short range, 10-20 meters)
> > My project :
> > Outside: an autonomous weather station (Wind speed, temperature and rain
>gauge),
> > using a PIC 16F84, and powered by solar cells and battery.
> > Inside :a terminal part that uses a PIC 16F84 too with LCD display.
> > I plan to use a one way wireless transmission between the two 16F84,
>using
> > 432MHz commercial modules : (1 time per minute, emitter on the station,
>receiver
> > on the terminal).
> > Does any of you have experience with reliable way of doing this Wireless
> > transmission (kind of protocol, modulation,etc.), or site to visit or
>code
> > snippets to grab.
> > MTIA
> >
> > FYI -
> > I have finished a one year old hobbyist project, a LCD frequency counter
> > Range few Hz to over 1.2 GHz
> > 16F84 (sampling rate ~1.2 sec.)
> > ECLinps input stage and prescaler (SMD components)
> > TCO 10 MHz for 3 ppm accuracy
> > 16x1 LCD display 10 digits display (resolution 1Hz)
> > Input A : few Hz to over 200MHz input level 200mv
> > Input B : 1 MHz to over 1.2GHz 400 mv
> > Power 4x1.5V AA cells + DC/DC converter -  auto off, low battery warning
> > I will try to put it on my first web site in the coming months
> > I established also the schematic for a simpler version with 120 MHz
>range
>only
> > (not tested)
> >
> >  [Gerard Mantoux           email: gerard.mantoux@bull.net
> >  Bull S.A.   38, Route de Versailles    tel: (33) 01 39 66 50 90
> >  78430 LOUVECIENNES, France        fax: (33) 01 39 66 67 94
> >  OPINIONS ARE MY OWN & DO NOT NECESSARILY REFLECT BULL POLICIES]
>
>Usually that's done with ASK, amplitude shift keying. This is what most
>garage door openers use. The transmitter can be done with one transistor
>oscillator which is keyed on and off by the data. The receiver is a bit
>more
>complex but still not too bad. Most receivers are super regenerative. I'm
>not sure off hand where to find plans but you could buy a cheap remote
>on/off switch from Radio Shack and copy it. Digi-Key also has some remote
>control stuff made by Ming Microsystems.
>
>Dan Mulally

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

</x-flowed>