From: Phil Hobbs
Subject: Re: Sending an analog signal using RF components
Date: Fri, 25 Oct 2002 13:23:43 -0400
Organization: IBM T. J. Watson Research Center
NNTP-Posting-Date: 25 Oct 2002 17:23:45 GMT
X-Mailer: Mozilla 4.61 [en] (OS/2; U)
> I need to transmit an analog signal, ranging from 400 mV to 1V, to
> a point 100 feet away.My signal varies constantly(Not only 400mV or
> 1V, can also have any values in between).I also want to have the least
> number of parts possible because of budget limitations and space
> I think that I have 3 possible solutions:
> 1)Send that signal as it is.But I don't think there's a part that can
> send an analog signal by RF??
> 2)Convert that signal into a digital signal.Is there something that
> can send an at least 8 bit digital signal by RF?? I need to be as
> precise as I can.
> 3)Convert that signal into a serial signal.But then I would need a
> clock,a frame with a header,etc..
If this is slow telemetry, e.g. for a weather station, you can use a V-F
converter such as an LM331 to send a tone over a cordless phone, and
receive using a F-V converter based on something like an LP339
comparator and a charge pump. Life doesn't get much simpler than that.
Accuracy will be about 0.2-0.5%, probably mainly in the F-V converter
(the 331 is very linear).