Specifications

MDS 05-3438A01, Rev. E MDS 4790/9790 Series I/O Guide 25

Coordinating Activities by Orderwire

The orderwire channel can be very useful in coordinating the set-up and

testing of two MDS 4790/9790 radios set up in a Polling Remote system

configuration. With a telephone handset plugged into the ORDERWIRE

jack (J9) on the radio’s rear panel, technicians can talk to each other

freely by merely speaking into the handset.

The telephone handset with a carbon microphone element can be

plugged into J9 on the rear panel to communicate with someone at the

radio of the link. Handsets suitable for use with the radio are available

from MDS (Part No. 12-1307A01).

Normal system operation is unaffected if all you do is listen over the

handset. However, when you speak into the handset, transmit audio is

applied to an automatic voice-operated transmit keying (VOX) circuit,

keying the transmitter.

At the same time, the VOX circuit switches off external transmit data,

interrupting the normal flow of data in the system. Transmit audio from

the handset is then applied to the transmitter. Your voice can then be

heard through a handset at the remote radio. Since any noise over the

handset interrupts transmission, you should unplug the handset when it

is not being used.

Troubleshooting Tip You can listen to network data activity using the handset. While us

humans cannot interpret the data by ear, the normal characteristics of the

data exchanges between the master station and remotes can be learned.

Once you know the “normal” pattern, you can recognize some changes

that as abnormal. To prevent the interruption of payload data, remove or

disable the handset mouthpiece (microphone element). The use of a

handset as an activity monitor is no substitute for electronic test equip-

ment such as a bite-error (BER) tester.

5.2 Front Panel Indicators

Refer to Figure 23 and the following text for an explanation of the front

panel indicators. The control buttons are described in Section 6.4, Con-

ﬁguration and Programming using the Front Panel, beginning on

Page 56.