DS006-2

Oct 02

2003 REG No 277 4001, ENGLAND.

Page 2

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 50

Ω 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.