QI am building a robot using a model 2 Raspberry Pi as its brain and would like to add two transceivers with a
1,000 yard range for monitoring and
controlling the robot. I would like to
know the best way to do this.
I would like the first transceiver
to have two USB ports for the
keyboard and mouse; then, be able
to receive the HDMI signal from the
second transceiver and display it on a
HDMI monitor. The second
transceiver should be able to receive
the signal from the keyboard and
mouse, sending the information by
way of the USB to the Raspberry Pi.
— Timothy Harner
AThere are many USB and HDMI capable transmitters and receivers available on the World Wide Web, but
their range is limited to about 300
feet due to the FCC’s (Federal
limitation on power output. The
Raspberry PI has two USB ports and
an HDMI output plus a GPIO port,
so you could have a configuration
like Figure 3 with a 300 foot range.
The only way to have more range
that I am aware of is to use the
27 MHz citizen’s band which has six
data channels and allows a maximum
of five watts. There is a one watt
module made in New Zealand which
claims a range of 3,000 meters. You
will have to build the interface
yourself; I suggest Manchester coding
because you can do that in software
and use the GPIO port of the
Raspberry Pi (see Figure 4).
If you want full duplex
communication, you will need to put
the two transmitters on different
channels. Otherwise, you could turn
off one transmitter while the other is
transmitting for simplex
22 November 2013
■ FIGURE 4.
■ FIGURE 3.