Motorola P Series Manual de venda - Página 27

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Detailed Features/Benefits Description

If the store manager receives a customer query relating to the availability of a hardware product, he

can simply click to position 4 on the channel selector knob and talk to the Hardware department,

without disturbing the staff in other departments.

PL is often a licensing requirement for community repeaters where several different companies

share a common repeater infrastructure. PL prevents communications from one company being

heard by the others (and vice versa).

The Motorola Private Lineª signalling system actually consists of two different signalling schemes:

TPL - Tone Private Line - sub-audio tones continually transmitted with the audio signal (also

called CTCSS - Continuous Tone Controlled Signalling System)

DPL - Digital Private Line - sub-audio digital code continually transmitted with the audio

signal

Another beneÞt of using PL is that it eliminates the annoying "squelch tail" typically associated with

two-way radio communications. The elimination of the squelch tail improves the quality of

communication and means that conversations are easier to follow and understand.

The squelch tail is a short burst of channel noise heard by the receiving radio when the PTT is

released on the transmitting radio. This is caused because the receiving radio does not immediately

recognise that the transmission is over and squelch is momentarily held open, even though carrier is

not present.

PL prevents this by generating a reverse burst (for TPL) or a "turn off code" (for DPL) at the

transmitting radio when the PTT is released. The receiving radio instantly recognises the reverse

burst (or turn off code) and squelches the speaker audio.

The reverse burst (or turn off code) can be enabled or disabled using the CPS.

The P Series CPS allows you to program different transmit and receive PL codes on a per-channel

basis. TPL codes within the frequency range 67.0Hz to 254.1Hz (inclusive) are supported, as well as

the standard EIA/TIA-603 codes (including 2 non-standard codes).

3.4.2

Variable Squelch Settings

The Squelch setting, programmed into the radio on a per-channel basis, sets the criteria for

unmuting the radio speaker.

The Squelch setting ensures that the radio user only hears the necessary conversations - unwanted

channel noise is effectively Þltered out.

The P Series radios support two different types of Squelch :

Carrier Squelch : the radio speaker unmutes whenever carrier is detected on the channel

PL Squelch : the radio speaker unmutes when the appropriate receive PL code is detected on

the channel

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