n2nov.net

[BxScan]

Whenever I hear transit field units (i.e. train operators or conducters) transmit, the transmission is proceeded by a fairly long data burst. Is this simply a PTT unit identifier, or does the data burst serve another purpose, such as opening up a squelch system or a repeater input?

If it is a PTT identifier, then why does the dispatcher always have to ask for the unit to ID anyway?

[LIBUFF]

many data bursts at the beginning of the messages are in the format of MDC1200 or GE-Star. they do send identification that is programmed for each radio... MDC is 0001-DEEE (in Hex), and GE-Star is 0001-16500 (not exaclty sure on the number, but its decimal)...

for an example, in the FDNY EMS system, the portables and mobile radios in the ambulances are programmed with an MDC1200 code which is just number, for example purposes, EMS unit 10Adam, may have Mobile# 2115, Portable # 1234, 5678...

now the dispatch computer at EMS is programmed to receive that identifier and display 10A to signify what unit is speaking, but that depends on the units input when logging into the system.

most radio identifiers are used for secondary purposes, to confirm what unit is speaking, however, there are circumstances where a false-id may be displayed. examples may be co-channel users who are also utilizing the same signaling...

[slamcac]

the data bursts identify the radio number and the employees TA pass (ID)
number. (if properly logged on) TA train crews still cave to identify themselves with train call letters
for example,

"control center, this is the 1915 Fox 179 train operator reporting a red signal at....."

in plain english
7:15PM "F" train out of 179th St
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THE RED, THE BLACK and THE GREEN !!!

[CEFX 1037]

If the employee TA pass is also added to the data burst, does this mean that every motorman/conductor is assigned to have their own radio?

[slamcac]

Yes it does, You take the radio home with you and you had better bring it back to work when you are to report for duty !!!. That is why you will sometimes hear a child talking on either "A", "B1" or "B2" the -repeaterized channels
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THE RED, THE BLACK and THE GREEN !!!

[MustangFan424]

This is wrong info about transits data burst. Their radios are Vertex Standard 900s with a special mod by vertex to allow crews to change the G.E Star Data burst on the fly. The G.E star data burst that transit has is one of a kind and no one else has it because its format made for transit only. The burst goes as follows, 222-1234. First 3 digits are your crew number, last 4 digits are your interval (time the train left terminal) The emergency button is also programmed to send out a G.E star emergency signal, but, when you press it the radios are not set with a delay to open the repeater before it sends the burst. This causes the burst to get chopped off and be useless.

The whole system is not even used by transit and there is no way to decode any of the IDs at rail control center. So basiclly it was a waste of time to even build the G.E star system for transit and all it does it take up air time when people unkey their radios. The only radios in transit with no data burst are the cab radios found in the R142, R143, and R160 cabs. The R142s and R143s have Bendix King Mobles, The R160s have vertex mobiles.
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-Phil