Newsgroups: comp.robotics
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From: alasdair@aisb.ed.ac.uk (Alasdair MacLean)
Subject: Re: R/C transmiter output
Message-ID: <D013E7.888@aisb.ed.ac.uk>
Sender: news@aisb.ed.ac.uk (Network News Administrator)
Organization: Dept AI, Edinburgh University, Scotland
References: <D00104.JtE@stortek.com>
Date: Tue, 29 Nov 1994 12:15:42 GMT
Lines: 30

In article <D00104.JtE@stortek.com> daveh@atlantis.stortek.com (David Helms x4098) writes:
>Hi all,
>
>I have a question that I haven't been able to figure
>out and am looking for some info. The ? deals with the
>output of an R/C transmitter and receiver. I understand
>that the transmitter puts out variable pulse widths
>based on the position of the joysticks. What I don't
>understand is how a receiver knows weather I want to
>reverse or not. 
[snip, snip]
>Thanks for any response.
>
>dave

If I remember correctly, the spec. for hobbyist control in the 27Mhz
band is something like this:

Channel1 is a burst of RF for 1-2ms, followed by 0.5ms off time.
Channel 2 follows, again RF for 1-2ms, followed by 0.5ms off time.
If the system is 6 channels there follows a 1ms burst corresponding 
to the logic level of each of the 4 remaining channels, again followed 
by a 0.5ms modulation 'gap'. Otherwise the next signal is the sync.
This is a burst of RF which is kept on until a total of 20ms 
( the frame duration ) has passed.
If we're talking about model cars, a pulse on channel 2 (?) of 1.5ms
will turn the motor off, whereas a longer or shorter pulse will send the
motor into forward or reverse.
Hope this helps.

