December 2017 13
While I have seen FRS and GMRS radios in Walmart, Best
Buy, and other places, I have not encountered MURS units.
I’m beginning to think that MURS is a stealth radio service.
If you go online, you will spot dozens of choices from
manufacturers like Cobra, Motorola, etc.
If you’re looking for data radios, a great source is
Lemos International. They are resellers of Radiometrix
wireless modules. This UK manufacturer offers a huge
range of different data radios.
I had a chance to play around with some of the
Radiometrix NiM1B modules (see Figure 1). These are
small, low cost, and easy to use. These would be a great
option for a long range Io T project.
I used the 154.57 MHz module with NFBM
modulation and a data rate up to 5 kb/s max. The
transmit power is 13 dBm, or 20 m W. The receiver
sensitivity is -120 dBm. This combination with a
decent antenna should be good for several km.
I also experimented with the Radiometrix QPX1-
154-5-MURS transceiver (refer to the right-hand side
of Figure 1). The unit will put out a full two watts,
and the receiver sensitivity is -118 dBm. The transceiver
uses the 154.57 or 154.6 MHz channels, but the unit may
be reprogrammed to any frequency in the 135 to 175
MHz range. The I/O is standard RS-232 with a typical data
rate of 1200 baud (bps, in this case). I didn’t test for range,
but it should be impressive.
If you’re looking for a MURS data radio, go to the
Lemos website ( www.lemosint.com) and take a look.
There’s a lot to choose from. Prices are right and the tech
support is excellent.
When you need another communications alternative,
be sure to consider MURS. It is certainly not well known,
but is an attractive and very affordable option. NV
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Figure 1. The Radiometrix NiM1B modules are shown
on the left. The unit on the right is the QPX1-154-5-
MURS transceiver. These and other units are distributed
by Lemos International ( www.lemosint.com).