Elenco Deluxe Snap Rover® - Manual (Page 7)

Remote Control Transmitter:
When the levers in the Remote Control Unit are pushed, electrical
contacts are made connecting the 9V battery power to the transmitter,
indicating which commands the user wants sent to the Rover.
Forwards/Backwards commands for each set of wheels and two extra
functions are controlled by different levers or buttons. Each of these use
a different set of electrical contacts which encode a sequence of
electrical pulses; the pulse sequence depends on which command(s) are
being sent. The spacing between the sequences represents which
channel setting (A-B-C) the remote control is on. This allows three units
to use the same operating frequency in the same room at the same time
without interfering with each other. An electrical circuit that is tuned to a
frequency of 27 MHz creates a signal that is sent to the antenna when
the pulses are active. The antenna converts this electrical energy into
radio energy, creating a stream of radio energy bursts, which travel
through the air and are picked up by, and understood by, the radio
receiver in the car. The frequency of 27 MHz was selected for your Rover
with the approval of the FCC (the US government) to minimize radio
interference between this product and all other electrical products.
Radio Receiver:
The Rover antenna collects radio energy and converts it back into
electrical energy. If the Rover is turned on, then the radio receiver in the
Rover is continuously monitoring the radio energy from its antenna. The
receiver is basically a filter which is tuned to amplify any energy around
27 MHz and block energy the antenna picks up outside this region. If the
Remote Control Transmitter is sending commands, then its radio signal
will be picked up by the receiver and converted back into the original
pulse sequence. Decoding circuitry then determines which commands
were sent by examining the pulses in the sequence. Signals are then
sent to motors that drive the wheels to execute the commands, or the
other R/C Receiver outputs to control other functions. Commands sent
to other receivers using a different channel setting (A-B-C) are ignored.
Characteristics of Radio Reception:
Many factors affect the ability of the Rover to receive commands from its
Remote Control Transmitter. A weak battery in the Transmitter will result
in a weaker transmitted signal; if the battery is very weak then the
Transmitter may not function at all. The Transmitter’s ability to convert
electrical energy to radio energy is best when its antenna is fully
extended and degrades as the antenna length is reduced. The same
thing also applies to the Rover antenna’s ability to convert the radio
signal back into electrical energy for the receiver. The Transmitter’s
antenna transmits energy in all directions so as the range between it and
the Rover is increased, less energy is received at the Rover. When
operated with strong batteries and in an open area, the range will be at
least 25 ft. Obstacles such as walls, furniture, and trees will degrade the
radio signal’s ability to travel through air and reduce the operating range,
but will never block it completely. In some cases more radio energy may
travel from the Transmitter to the Rover by going around obstacles than
by going through them. In the Rover, weak batteries will reduce power
to the motor and degrade the receiver’s ability to filter, amplify, and
decode commands from the Transmitter.
Encoding
Circuitry
27 MHz
Signal
Filter/
Amplifier
Filter/
Amplifier
Decoding
Circuitry
L-F
L-B
R-F
R-B
Pulse Sequence,
depends on which
command(s) are being
sent and channel used Sequence
of Radio
Frequency
Pulses
Pulse Sequence,
depends on which
command(s) were sent
and channel used
128-1
Gear Ratio
Left
Wheels
Left
Motor
128-1
Gear Ratio
Right
Wheels
Right
Motor
How It Works
L BUT
R BUT
Control For Two
Other Functions
BLOCK DIAGRAM
HOW IT WORKS
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