EFJohnson 7780 service manual Standard Conventional Calls, DTMF/ANI Signaling

TRANSCEIVER OPERATION

channel is sampled while listening to a message on some other channel.

The priority sampling times are programmed by the following parameters:

Lookback Time A - This time determines how often the priority channel is checked for activity. Times of 0.25-4.00 seconds in 0.25-second steps can be programmed.

Lookback Time B - This time determines how often the priority channel is checked once an incorrect Call Guard (CTCSS/DCS) code is detected. Since it takes much longer to detect an incorrect Call Guard signal than a carrier, this time should be relatively long to prevent the interruptions from making a message diffi- cult to understand. Times of 0.5-8.0 seconds can be programmed in 0.5-second steps.

Changing The Priority Channel

If a specific priority channel is associated with the current scan list, it can be changed if the Priority option switch is programmed. Proceed as follows:

1. Make sure all scanning is off (neither the standard

scan “ S” icon nor radio-wide scan icon displayed).

2.Select the channel that you want to be the priority channel using the channel selector switch on the top panel. If the channel is in a different zone, also select the appropriate zone.

3.Press the Priority option switch and the “ P” icon is displayed to indicate that the selected channel is now the priority channel.

2.4.13 STANDARD CONVENTIONAL CALLS

Standard conventional calls are calls to or from other mobile units on the selected channel. The proper coded Call Guard signaling (see Section 2.4.6) may need to be transmitted for them to receive your call and also for you to receive their calls. Proceed as follows to place and receive these calls:

Placing a Standard Conventional Call

1.Turn power on and set the volume as described in Section 2.3.2. Select the channel programmed for the mobile you want to call (see Section 2.3.7).

2.Monitor the channel automatically or manually as described in Section 2.4.3.

3.Press the PTT switch and the call proceeds as follows:

•If the Busy Channel Lockout feature is programmed on the channel, the transmitter is automatically disabled if the channel is busy (see Section 2.4.5).

•Otherwise, busy and out-of-range conditions are not indicated and speaking can begin after moni- toring the channel.

4.Press (and hold) the PTT switch to talk and release it to listen.

Receiving a Standard Conventional Call

1.Select or scan the channel programmed for the call you want to receive (refer to Sections 2.3.11 and 2.4.11 for more scanning information).

2.When the call is received, press the PTT switch to talk and release it to listen. If scanning, you may have to respond before scanning resumes to ensure that the response occurs on the channel of the call.

2.4.14 DTMF/ANI SIGNALING

DTMF (Dual Tone Multi-Frequency) tones can be generated manually or automatically for ANI (Automatic Number Identification) and other purposes. The following options may be enabled by dealer programming for each conventional channel:

DTMF Keypad - With full keypad (15-key) models only, pressing 0-9, * , or # on the keypad while holding the PTT switch transmits the corresponding tone until the key is released.

Pre-Tx ANI - A preprogrammed ANI sequence is automatically sent when you press the PTT switch.

November 1999
Part No. 001-7780-500	2-12