458MH
Z
RF S
YNTHESISED
T
RANSCEIVER
X7000
Frequency of Operation
The transceiver operate on the 458.500MHz to 458.950MHz telemetry band. There are 32 channels within
this band at 12.5KHz or 15 channels at 25KHz bandwidth.
The 5 DIL switches accessed from the top of the module set the RF frequency after power is applied or a
RST has occurred. The following frequencies will be set on the standard UK version:
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
1A*
458.825*
1C
458.850
1E
458.875
20*
458.900*
22
458.925
SW5
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
SW4
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
SW3
ON
ON
ON
OFF
OFF
OFF
OFF
ON
ON
ON
ON
OFF
OFF
OFF
OFF
ON
ON
SW2
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
SW1
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
* Excluded from MPT1329 approval and cannot be used for transmission.
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 0.5, 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 >2dB. 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 50Ω low loss co-axial cable should be used as the interconnection.
DS007_2
Oc t 00
©2000
REG No 277 4001, ENGLAND.
Page 2
RFSOLUTIONS [ RFSOLUTIONS.LTD ]
