Aeroflex 2946A Instructions d'exploitation télécharger pdf (Page 108)

OPERATING MANUAL 2945A

46882-311D 3-69

of the orange [ON/OFF] function key. If is selected, the tones are still controlled by

the orange [ON/OFF] function key, but if a frequency is entered using the data keys or if the

variable control is adjusted, the tones will cease. They can then be re-started only when the

SEQUENTIAL ENCODER

screen or the AF SEQUENTIAL ENCODER screen is displayed.

If the tones out routeing has been set to give AF tones, this is provided by audio generator 1. The

legend

--Tones-- will be displayed against AF1 FREQ on the TRANSMITTER TEST, DUPLEX or

AF TEST screens. If is selected, the tones can be controlled by repeated presses of the orange

[ON/OFF] function key. If

is selected, the tones are still controlled by the [ON/OFF]

key, but if a frequency is entered using the data keys or if the variable control is adjusted, the

tones will cease. It can then be re-started only when the

RF SEQUENTIAL ENCODER screen or

the

AF SEQUENTIAL ENCODER screen is displayed.

Testing sequential tone transmitters

To test the operation of transmitters sending sequential tones calling signals, proceed as follows:-

Select the Tx TEST mode, then make all the required settings and RF connections for

conventional transmitter testing. Refer to the Tx TEST section of this manual for the correct

procedures. Set the frequency of the Service Monitor input to that of the transmitter output.

Key the transmitter and check that the Service Monitor is obtaining a signal from the transmitter.

Select TONES mode. The attenuators in the receive path of the Service Monitor will be held at

their current setting. Press the [Sequential] key. The

RF SEQUENTIAL TONES DECODER

screen and menu is displayed. See Fig. 3-21, Sequential tones decoder screen. If the encoder

screen is displayed, press the [Decode] key.

Fig. 3-21 RF Sequential tones decoder screen

Check that the tones standard shown above the tone number/frequency list corresponds to the

system used by the transmitter. If this is not correct, select the correct standard from the menu

accessed through the [New Std] key.

Key the transmitter to transmit a tone sequence. Within the Service Monitor the TONES decoder

will decode the tones sequence obtained from the modulation meter.

The decoded sequence will appear in the panel at the top of the display, with the first 10

characters underlined. The sequence decoder store can hold up to 40 decoded characters. Any

received in excess of this will be lost.

The underlined tones are listed in the centre of the display with an analysis of the parameters of

each tone as below:-

• The measured frequency of each tone.

• The percentage error from the true tone frequency.

• The duration of each tone.

By using the [

] or [ ] keys, the analysis of all tones in the decoded sequence can be shown.

The stored sequence can be cleared from the store by pressing the [Clear Sequ] key.

1 2 ... 103 104 105 106 107 108 109 110 111 112 113 ... 236 237

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Aeroflex 2946A Instructions d'exploitation Page 108

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