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Harris / MA/COM / GE / Ericsson Forum - For general discussion of MA/COM EDACS and ProVoice systems, including equipment.

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Old 06-05-2017, 2:40 PM
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Default Conventional Scan Options

Why does conventional scanning work so much differently than trunk group scanning on these (P7100 P5100 P7200) radios? It's almost useless to use the priority scan,being that it cuts into the current channel activity, checking for the priority, to the point of it making the current channel unintelligible.

Does the radio not scan the current channel that the radio is parked on if "Always Scan Selected Channel" isn't selected? Does the radio pick-up any traffic on the selected channel if that feature is off? I seem to be getting mixed results.

Last edited by TDR-94; 06-05-2017 at 2:54 PM..
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Old 06-05-2017, 6:24 PM
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Trunked system scanning isn't actually scanning. The radio is getting low speed data on the working channel to perform priority revert. In conventional the radio is needing to leave the frequency to check the priority frequency.

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Old 06-05-2017, 9:31 PM
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The ability to NOT scan the selected channel is usually used for TWO-FREQUENCY SIMPLEX systems. (IE: base is on one frequency, the mobiles/portables are on a different frequency, where the users in the field cannot hear each other intentionally. Users in California are all too aware of this system!)

The reason for this is the radio needs to be scanning one or more receive frequencies for traffic, but only transits on a single frequency. You see in some older public safety systems and in Taxicab and Wrecker dispatch comms.

For most cases, you must have ALWAYS SCAN SELECTED CHANNEL checked.

Why you seen the audio "hole" when scanning conventional with PRIORITY is the radio must physically change channels to sample the priority channel for a signal. There are minimum time requirements to be able to do this. A plain analog channel without any CG or DCG is the fastest at about 30 milliseconds. And in a CG or DCG, then there is some additional overhead time required to validate the CG/DCG if present to see if it is valid. If it is a digital voice mode channel, even more time !!! I starts to add up quickly. This is simple time constraints which must be met to perform the required functions.

P1 is the worst. I samples every second. P2 is a bit easier to listen to, as it only samples the designated priority channel half as often.

If it can be avoided, I NEVER recommend P1 scanning on conventional for this reason.
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Old 06-06-2017, 8:03 AM
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It makes more sense to me now why it must work that way.Conventional P1 is certainly the worst!
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