LTR system "clicks" every 3 seconds

[W4KRR]

I know that an indication of a frequency being used by a standard LTR system is hearing "clicks" or like a mike keying every 10 seconds or so. But I have run across some frequencies where I hear this same type of clicking every 3 seconds. Is this indicative of any particular type of LTR system, like maybe Passport or some other type?

[cubn]

Sounds like LTR Passport to me.

[KCChiefs9690]

Originally Posted by cubn

Sounds like LTR Passport to me.

That doesn't means that it's Passport, all LTR systems make that noise. See this part in the wiki:

Typically on LTR systems, each of these controllers periodically sends out a data burst (approximately every 10 seconds on LTR Standard systems) so that the subscriber units know that the system is there. The idle data burst can be turned off if desired by the system operator. Some systems will broadcast idle data bursts only on channels used as home channels and not on those used for "overflow" conversations. To a scanner user the idle data burst will sound like a short blip of static like someone keyed up and unkeyed a radio within about 1/2 second. This data burst is not sent at the same time by all the channels but happen randomly throughout all the system channels.

[cg]

The original poster acknowledged the once every 10 seconds being common for LTR but was wondering about the shorter separation time. His guess about 3 seconds indicating Passport was correct.
Not every channel will have keyups but IN GENERAL approx 10 second interval in regular LTR and approx 2 second interval in Passport is accurate.

chris

[KCChiefs9690]

Originally Posted by cg

The original poster acknowledged the once every 10 seconds being common for LTR but was wondering about the shorter separation time. His guess about 3 seconds indicating Passport was correct.
Not every channel will have keyups but IN GENERAL approx 10 second interval in regular LTR and approx 2 second interval in Passport is accurate.

chris

Oh I guess I learned something new today then.

[W4KRR]

Originally Posted by cg

The original poster acknowledged the once every 10 seconds being common for LTR but was wondering about the shorter separation time. His guess about 3 seconds indicating Passport was correct.
Not every channel will have keyups but IN GENERAL approx 10 second interval in regular LTR and approx 2 second interval in Passport is accurate.

chris

I thought I saw somewhere where the once every three seconds indicated a probable Passport system, but I don't remember where I saw it. Thanks for the replies.

[slicerwizard]

PassPort systems normally (it's programmable) use a fast idle burst rate (one to three seconds) on home channels and collect channels because they're networked systems; a roaming radio can't wait for ten seconds for a site to identify itself.