Aeroflex 2946A Instructions d'exploitation télécharger pdf (Page 105)

LOCAL OPERATION

3-66 46882-311D

When using the AF INPUT connector for TONES operation, the [ ] and [ ] keys on the

TONES selection screen set the AF input sensitivity. The column headed

Audio, in the above

table, lists the AF input settings. The AF input signal level should be less than that shown for the

current setting.

Sequential tones

Overview

Sequential tones signalling systems use sequences of audio tones to control various functions of a

radio system. There are many systems in operation world-wide, all using up to 15 tones labelled

with the hexadecimal digits 0 to E with ‘No Tone’ as F. Some systems make use of extended

tones for certain functions.

Each version has its own tone allocation tables for the 15 tones and its own timing for tone

duration.

The versions for which tone allocation tables and tone duration values are included in the Service

Monitor are:-

CCIR ZVEI DZVEI EEA EIA USER 1 USER 2

The USER 1 and USER 2 tables allow tone frequencies and tone durations to be programmed by

the user.

This Service Monitor has encoding facilities with variable parameters which allow signals to be

produced for testing systems using precise values and adverse values. The decoding facility will

measure the frequency and duration of the received tones, match the results against the

appropriate look-up table and list the results with the identification of each tone.

Observe notes relating to signal routeing and RF input attenuators at beginning of this section.

See page 3-65.

Continuous sequential tones can be produced at the same time as CTCSS or DCS tones.

Using the decoder

The sequential tones decoder will function when the instrument is in the Rx TEST mode.

Press the [Decoder] key and the

AF SEQUENTIAL DECODER screen will be displayed. A tone

sequence fed into the AF input will be decoded and the results will be displayed.

Testing sequential tone receivers

Using the encoder

To test the operation of receivers using sequential tone signalling, proceed as follows:-

Rx TEST settings

Select the receiver test mode by pressing the [Rx TEST] key.

Set the RF output frequency of the Service Monitor to that set on the receiver.

Ensure that the RF generator within the Service Monitor is in the OFF condition. This should

remain OFF until the Service Monitor and the receiver under test are set up and properly

interconnected.

Make a suitable RF connection between one of the Service Monitor RF output connectors and the

RF input connector of the receiver.

Set the RF output level from the Service Monitor to an appropriate setting.

Select the ‘RF SEQUENTIAL TONES’ function by using the key sequence, [Tones],

[Sequential]. The screen and menu shown in Fig. 3- 19, RF Sequential tones encoder display,

main menu, will be displayed.

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 236 237

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Aeroflex 2946A Instructions d'exploitation Page 105

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