Newsgroups: comp.robotics
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From: nagle@netcom.com (John Nagle)
Subject: Re: Wireless Video Systems
Message-ID: <1993Feb5.051620.4913@netcom.com>
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
References: <93Feb2.104915est.122@orasis.vis.toronto.edu> <1993Feb4.235132.21524@ohsu.edu>
Date: Fri, 5 Feb 1993 05:16:20 GMT
Lines: 22

>(Narinder Bains) writes:
>> 
>> We are trying to send colour video signals from a colour camera onboard
>> our mobile robot (Cybermotion k2a) to the remote control station via
>> wireless means. We work in a large production facility (400ft by 200ft)
>> which contains numerous pipes metal pillars and heavy duty motors.

      Indoor TV with a moving transmitter is tough.  I tried FM TV, at
1.245GHz, with limited success.  Reflection nulls dominate, so there's
a bad signal every wavelength.

      The usual solution to this problem with wireless microphones is
a diversity receiver.  What's needed is two receivers with separate
antennas, with a switch to use the one with the strongest signal.
Such switching is usually done at the output of the IF, not at the
video level.  There's an advantage in using FM TV, although the
equipment is harder to get, because the amplitude variations don't
cause problems until the amplitude nears 0.

      This would be a nice construction project for a ham type.

					John Nagle
