am gasit un text destul de interesant.. vezi mai jos

pare un fel de id special compus din 5 tonuri, dar nu gasesc formularea cea mai inspirata, poate te ajuta textul...

SELCALL, 5-Tone
Selective calling (SELCALLl) is the closest thing to privacy on radio. Normally a system enables single users to call other single users, on the same system, without any other users hearing what is being said.
You can also define groups and sub-groups and program calls accordingly. Supervisors may have the functionality to call every user individually whereas the shop-floor staff may only have a group call facility.

It works in a similar way to CTCSS but uses 5 tones, sent when the transmit button is pressed, instead of a single continuous tone. The receiving radio is constantly looking for a signal on its frequency. When it sees that signal it checks to see if the CTCSS tone is present and correct, and then if programmed correctly checks to see if its 5 tone id is transmitted before it "unmutes".

5-tone is normally used if the radio operators require extra privacy or if the over-all radio system is quite large encompassing different departments within a company. Each user can have his own ID and can be called if the radio has the correct features. These features may be used either from a contact list or a numeric keypad.



With SELCALL individual units can be called from the Base. The called device will ring notifying the user that he is required. This is particularly useful where the driver is constantly out of the cab. When he returns a ring tone, or a flashing light, will indicate that the base was trying to make contact. The device can also be used to call the base. The display on the base will indicate the number of the device calling.



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Note added at 40 mins (2007-05-13 17:04:09 GMT)
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ar merge... codul special format din 5 sunete/tonuri ??? parca e prea lung