GAI-Tronics MRTI 2000 (No. PL1877A) Microprocessor Radio Telephone Interconnect Installation & Service Manual - Manual (Page 90)

Parameter Modification PL1877A Microprocessor Radio Telephone Interconnect
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Installation
The frequency is stored in parameter 358. Determine the number of 25-ms periods in the required
frequency. For example, if a frequency of 1 sample per second is desired, the value required would be 40
(hexadecimal 28) (40
× 25 ms = 1000 ms = 1 sec). The duration is stored in parameter 359. Determine
the number of 5-ms periods in the required duration. For example, if a duration of 40 ms were required,
the value would be 8 (8
× 5 ms = 40 ms).
Parameter Function
358 Number of 25-ms periods in the signal search frequency. Range = 10–100
359 Number of 5-ms periods in the signal search sample duration. Range = 3–20
Enhanced VOX Simplex Mode
Parameter Function
28 Disable enhanced VOX attention getting ticks = 0
Enable enhanced VOX attention getting ticks = 1
These ticks are sent to the landline user at the beginning of a mobile-originated call.
Their purpose is to hold the landline user’s attention until the mobile user seizes control
of the audio path, keeping the landline user from locking the station in transmit when he
answers the telephone. The ticks disappear upon mobile carrier detection after the
landline user answers the phone.
29
Disable enhanced VOX, land-line transmit timer = 0
Enable enhanced VOX, land-line transmit timer = 1
When the patch is being used in the enhanced VOX simplex mode, if landline audio is
continuous (keeping the transmitter keyed) for more than 30 seconds, the landline
transmit timer unkeys the transmitter for 5 seconds to allow the mobile to take control.
Caution: FCC regulations in many services require the landline transmit timer to be
enabled.
34 Disable mobile go-ahead beep = 0
Enable mobile go-ahead beep = 1
The mobile go-ahead beep is sent to the mobile user when the PL1877A detects loss of
landline VOX. It signals him/her that it is his/her turn to talk.
127 Enhanced VOX receive recovery delay: number of 50-ms periods in the delay between
transmitting and receiving in enhanced VOX mode. Valid range = 0–8
Some radios have an inherent delay between transmitting and receiving during which the
radio receiver and/or carrier detect outputs are invalid. The PL1877A must be
programmed to ignore receiver audio squelch and carrier detect logic during this period.
Otherwise, transmitter cycling could result when receiving dial tone or busy tone on the
phone line.
514 Enhanced VOX delay. Valid range = 0–100. Default = 100. This parameter determines
how long (in 5-ms increments) phone line audio is delayed before being presented at the
TX audio port in the enhanced VOX mode.