NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/rec/models/rc/5626

Text File | 1993-01-21 | 2.2 KB | 44 lines

Newsgroups: rec.models.rc
Path: sparky!uunet!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!malgudi.oar.net!news.uakron.edu!VM1.CC.UAKRON.EDU!D2KAK
From: [e-mail]
Subject: Re: Question about R/C receivers
Message-ID: <[e-mail]>
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Organization: The University of Akron
Date: Thu, 21 Jan 1993 12:36:29 GMT
Lines: 33

There are several different types of receiver in use today. First
of all the transmitter does not send out four different signals.
The transmitter sends out one signal with all of the information
for the diffrent channels. In a standard AM or FM radio system,
the information is sent as a stream of pulses of varying width.
As you move the stick on the transmitter, you change the width
of the pulse sent to the receiver. These pulses are transmitted
to the receiver in a fixed order (usually aileron, elevator,
throttle, and rudder in that order). The pulses are usually set
around 1.5-1.6 msec when the controls are centered. The extremes
range from .9 msecto 1.9 msec.
      In the receiver the pulses are sent to a decoder (usually
some type of shift register) which sends the proper pulse to the
proper channel. In addition the transmitter sends one pulse which
is far longer than a standard channel pulse. This pulse serves to
reset the receiver in preperation for the next pulse train.
     In PCM radios, the information on stick position is transmitted
to the receiver (also as a train of pulses) in the form of serial
binary numbers. The length of the binary number determines the resolution
of the system (hence 512 or 1024 bit resolution). A dedicated microprocesor
in the receiver then decodes the information and sends a pulse to the
appropriate servo. This pulse is identical to the pulse sent in a standard
system, which is why you can use servos interchangeably in both types of
systems.
     This is only a brief, non-technical description of the workings of a
modern radio system. There are many more circuits used to modify the
information prior to transmitting and of course the RF sections of the
radio system itself.
     Hope this helps a little.
Kraig Krumm  (AMA59622)
The University of Akron
Electronic Systems