458MH
Z
RF T
RANSMITTER
& R
ECEIVER
TX/RX6000
Frequency of Operation
The TX/RX6000 modules operate on the 458.500MHz to 458.950MHz telemetry band. There are 15
channels within this band. The TX/RX6000 modules are supplied at one of these specific channel
frequency bands. When ordering the modules, the exact frequency must be stated.
Ch No (Hex) Frequency (MHz)
02
458.525
04
458.550
06
458.575
08
458.600
0A
458.625
0C
458.650
0E
458.675
10
458.700
12
458.725
14
458.750
16
458.775
18
458.800
1C
458.850
1E
458.875
20
458.900
22
458.925
Radio Propagation
With any radio system, there are a number of factors affecting the system performance. These are
•
Transmitter power output
•
Height of transmitter and receiver antenna
•
Length of feeder cables to the antenna
•
Type and efficiency of antenna
•
Surrounding topography
•
The weather
Antennas
The types of antenna we recommend for this Modem are;
Helical
: The smallest, most compact antenna, has a gain of <1, designed for short ranges up to 2km
1/4 Wave Flexi
: General purpose antenna with gain <1 gives slightly better range than Helical
Yagi
: A highly directional antenna (Looks similar to a standard TV aerial). Typically has a gain of +3dB.
The output power of a transmitter connected to a Yagi must be reduced in order to comply to the DTI
specifications. This does however have the advantage of reducing the power consumed by the transmitter
to achieve the same range. By connecting a Yagi to a receiver, the system range may be extended to
20km.
Note
: Try to keep the feed wire to the antenna as short as possible, If the antenna is to be mounted some
distance away low loss 50Ω co-axial cable should be used as the interconnection.
Power Supply
It is not advisable to use a switched mode power supply, either to drive the TX6000/RX600 module or
within close proximity to it. Switched mode power supplies can produce high energy radio frequencies over
a broad spectrum potentially causing interference with the operation of the Modem.
DS006-2
Oct 02
2003
REG No 277 4001, ENGLAND.
Page 2
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