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[DPRG] Multi-robot communication

Subject: [DPRG] Multi-robot communication
From: Mike McCarty jmccarty at ssd.usa.alcatel.com
Date: Tue Aug 29 11:28:15 CDT 2000

On Tue, 29 Aug 2000, James Andrew Smith -- Onnimikki wrote:

> Got the Ramsey radios yesterday and they're not as "plug-and-play" as I
> had hoped... but then again, nothing ever is.

Ain't it the case!

[snip]

> to accomplish.  One alternative is to get a pair of Radio Shack
> walkie-talkies, emit a 1 kHz tone on one and decode the tone on the other.  
> The decoding is done by a LM567 decoder chip.  You set the LM567 to decode
> a given tone/frequency and it spits out a 5volt pulse when that happens.
> 
> Luckily I bought a rail of the '567s last year while working on a sonar
> project... now I'll get to use them! (-:
> 
> The chapter also discusses using UARTs tied to the previous radio
> stuff.  I only glanced at it and didn't read much, so I'm not sure how
> applicable it is yet.

This is ok if you only need unidirectional communications. I already
looked into this some time back, and even bought some walkie-talkies at
Radio Shack (when they were on sale after Christmas, for $2.50 each).
But the switching between xmit/rcv is based on a 4PDT (or was it 6PDT)
switch. That looked too messy to me. I'd need to build relay
connnections or something, and relays are not cheap either in power or
in $ or in space. For me, the space was not such an issue. The output
would need to be qualified with a carrier detect, as well. I suppose
this would not need to be a separate bit, but could just be ANDed with
the data stream, so there could be no start bit without carrier.

HDX is ok for my app, but I do need bidirectional, and the RX/TX
switching just looked too much for my taste.

Mike



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