Re: Tuning into an square wave radio transmitter
- From: "Anders Nesheim Vinje" <a-vinje@xxxxxxxxxx>
- Date: Thu, 26 May 2005 22:18:00 +0200
"John Fields" <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:s68c91tsg42c8qeopmg4o58raj0b1srqnv@xxxxxxxxxx
> On Thu, 26 May 2005 18:01:29 +0200, "Anders Nesheim Vinje"
> <a-vinje@xxxxxxxxxx> wrote:
>
>>Hello. I was wondering how to filter out a 1MHZ square wave radio signal.
>>I
>>got the sender working correcly.
>>I am sending this as digital data to a pic controller.
>>My first thought was to use capacitor and a coil in paralell. And find the
>>high impedance frequency by using the formula 1 / (2pi * squarerot(C*L)).
>>Now i am not so sure. I guess this only works for a sinewave signal.
>>So does anyone know how to filter out any other signals below and above 1
>>MHZ of a square wave signal??
>
> ---
> Could you supply a little more detail, please?
>
> 1. What do you mean by a "1MHZ square wave radio signal"?
> It is a crystal oscilator connected to the parallelport of a computer.
> When i put a 5 volt high its input i generates a 1Mhz squarewave signal.
> The output is conected to an anntenna. Its based on this
> http://www.scitoys.com/scitoys/scitoys/computers/radio/computer_controlled_transmitter.html
>
> 3. When you say that you're sending it as digital data to a PIC, do
> you mean that you have the 1MHz signal connected to it directly, or
> do you mean that you're sending it as a CWRF signal, or do you mean
> that you're modulating a carrier with a 1MHz square wave, or ????
The purpose is to recive the 1Mhz signal and translate to a 1 when signal
is present and 0 when not present. I do need much data transfer since it
only
is supposed to control 2 electric motors. After amplification and rectifing
(and tuning) i was thinking of using a capacitor to ground, charging up when
the signal is present so its dc componet will be close to 5 volt. And a 5,1
volts zenerdiode to limit the voltage. Then have a resistor to ground so its
allowed to charge out when the signal is no longer present.
This might be a stupid idea on how to transmit data from one device to
another but i am kinda new to this so any other suggestions would be much
appricated.
The only thing is that i want it to be simple and that only signal that can
be recived is the 1 Mhz.square wave. I guess that modulating it with a sine
signal and then
tune into that frequency on the reciver might an option to. Or if its
possible to convert the square wave to a sine signal at the transmitter
might be even better.
Well i am open for suggestions.
> 4. If you run the 1MHz square wave signal through either a lowpass or
> a bandpass filter such as the tank (the parallel LC) you've
> described, the harmonics of the square wave will be attenuated and
> the output of the filter will be mostly a sine wave with the same
> period as the square wave. Is that what you want?
Will this convert the square wave into a sine wave at the samme frequency??
Thank for you answers.
Anders N. Vinje
.
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