Operating instructions

OPERATING MANUAL 2945A
46882-311D 3-75
Press the [Tones] key to display the screen shown in fold out diagram (3-5). The [DTMF] key
will then give access to the RF DTMF ENCODER screen.
Formatting a tone sequence
To create the required tone sequence, first press the [Enter Sequ] key to display the cursor in the
tone sequence panel. If the tone sequence panel is not empty use the [DELETE] key to clear the
sequence.
Enter the required sequence by using any of the 16 available characters of the DTMF keypad.
Pressing the equivalent data key on the front panel will cause the character to be entered in the
sequence panel. The cursor then moves to the next position and a second character can be
entered.
Any number of Null Tones can be included in a tone sequence. A Null Tone is a silent period,
and has a duration of one tone period. It is indicated in the tone sequence panel by a dash ( —)
To enter a Null Tone in a tone sequence, press the [Null Tone] key once.
A maximum of 40 characters can be included in a sequence, any further entries will over-write
the existing sequence.
Editing a tone sequence
An existing tone sequence can be edited as required. Using the rotary control, move the cursor
over the character to be changed. To delete the unwanted character and insert a new character in
its place, press the data key corresponding to the new character. To delete an unwanted character
and close up the sequence, press the [DELETE] key.
Tones modulation level
The modulation level produced by each tone of the tone pair can be set independently.
Pressing the [Lo Tone Level] key will highlight the legend
. The modulation
level can then be set using the data entry keys.
The modulation level produced by the tones is set using the [Lo Tone Level] or [Hi tone Level]
key, followed by use of the data input keys. The modulation level limits are 25 Hz to 75 kHz FM
or 1% to 99% AM. Attempted entries outside of the values will be ignored. The default level is
1.5 kHz.
The modulation level produced by each tone of the tone pair can be set independently. Levels of
the two tones can be locked using the [Lock Levels] key. This key toggles between the locked
and unlocked condition. When going from unlocked to locked, the latest level set will be taken
by both tones.
The tone duration and the pause duration, (time between each tone) can each be set
independently, from 20 ms to 1.0 s. The default values are 150 ms duration and 50 ms pause.
A tones frequency shift facility is provided for testing decoder circuits. To shift the frequency of
the transmitted tones press the [Freq Shift] key to highlight the
legend on the
display and enter the percentage value of the shift required using the data entry keys. Frequency
increases or decreases are possible. Entering a negative value will cause the transmitted
frequencies to be decreased from the stated frequency. The maximum frequency shift is 10%.
When the DTMF TONES functions are set, return to the Rx TEST mode and enable the RF
generator. Return to the DTMF RF ENCODER function. Press the [Send Mode] key to display
the Send Mode menu. The options available are:-
[Cont Tones] Generates the tone sequence repeatedly until the orange [ON/OFF] function
key is pressed.
[Tone Burst] Generates one sequence of the tones then stops.
[Step Tones] The first press causes the first tone of the sequence to be generated for the
duration specified. When the [Step Tones] key is pressed again, the next tone in the
sequence will be generated for the duration specified.