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Old 11-06-2013, 8:00 PM
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Cool MPT1327 Question

Could/Would/Should a MPT1327 system have the same SiteID on different frequencies?

Here's my problem. I can tune into several control channels and get their SiteID. One thing I'm seeing though, is that on the Adjacent Sites list, those SiteIDs and Channel numbers don't make sense.

I have the correct base frequency plugged in... so why would it point to a wrong channel?

Should I just not trust the Adjacent site data that's given?

Last edited by nickcarr; 11-06-2013 at 8:05 PM..
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Old 11-07-2013, 3:53 AM
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Quote:
Originally Posted by nickcarr View Post
Could/Would/Should a MPT1327 system have the same SiteID on different frequencies?

Here's my problem. I can tune into several control channels and get their SiteID. One thing I'm seeing though, is that on the Adjacent Sites list, those SiteIDs and Channel numbers don't make sense.

I have the correct base frequency plugged in... so why would it point to a wrong channel?

Should I just not trust the Adjacent site data that's given?
Don't know if this will answer your question.

1. It seems that a lot of systems come out with a Default SiteID (2309 - I think), so if the people setting up the systems don't bother changing the Default SiteID, you end with a number of unrelated Sites in an area, all with the same SiteID.

2. In Australia, we often have a VHFsystem, and a UHF system on the same Site. Both systems are owned by the same Business, and have the same SiteID. The two systems are NOT interconnected.

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Old 11-07-2013, 1:23 PM
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Cool

Thanks for the response. Apparently, our power company decided to emulate the rest of the Western USA and upgraded to this fancy MPT-1327 system. It's on 217 Mhz.

At times, we've had really bad storms and my guess is that so repair crews (from any state) don't need to use multiple radios. So these companies decided to all go with the same system.

So far, each control channel seems to use a unique ID but I'm getting conflicting results when looking at Trunkview's adjacent sites. It reports that this site is on X channel but that doesn't jive.

I'm 99% sure that the base frequency is correct as it jives with everything else I've seen/heard.

I'm thinking that I might be picking up an alternate tower with the same ID but on a different frequency -- possibly to increase its range.
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Old 11-07-2013, 3:06 PM
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So far, each control channel seems to use a unique ID but I'm getting conflicting results when looking at Trunkview's adjacent sites. It reports that this site is on X channel but that doesn't jive.

I'm 99% sure that the base frequency is correct as it jives with everything else I've seen/heard.

I'm thinking that I might be picking up an alternate tower with the same ID but on a different frequency -- possibly to increase its range.
OK, a quick reply, as I am supposed to be somewhere else.

The Base Frequency concept only works if the system uses contiguous Channels / Frequencies.

In Victoria, Australia, there is a Statewide system that basically goes from Channel 161 (164.0625) to Channel 251 (165.1875) in 12.5 kHz Steps,

You would expect 165.2000 to be Channel 252, but it is Channel 301, and the Channels go on from there up to Channel 364 (165.9875).

In TrunkView, you have to create a Custom Band Plan for this type of system,

Post some of the "wrong" Channel / Frequency pairs, and I might be able to come up with the required plan.

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Old 11-07-2013, 9:47 PM
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I'm thinking that I might be picking up an alternate tower with the same ID but on a different frequency -- possibly to increase its range.
They are possibly using a Cell Extender.

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Old 12-19-2013, 10:20 PM
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the fist two digits are the operator and the second 2 are the site so for example 0081 is site one and 0089 is site two,00a1 site 3 and son on,so the radios look at the first two digits to see if they should be on that system
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Old 12-19-2013, 10:21 PM
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you might find it interesting to know that there are more mpt1327 systems on the planet than all the other kinds put togther
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Old 12-20-2013, 6:12 PM
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Default MPT-1327 Question

Nick I am curious, is the power system you are monitoring using NFM? The reason I ask
is that I am seeing a lot of 1 - 2 second burst of data in the 220-222 mhz range. But the
modulation seems to be ACSB (Amplitude Condensed(?) Side Band). It is possible that it is
LTR. I can monitor LTR but am not familiar with MPT-1327. Does it's control channel burst or
is it continuous. I can't remember the site that has all the sample audio's to compare.
Again the reason I am asking is that I have a Power system close by that is licensed for 220-220.
I've tried Unitrunker, LTRAnalyzer and Trunkview and none of them seem to accept the audio.
I've also tried AM, NFM, USB and DMR with a SDR dongle. The only one to get any audio is the
USB and DMR, and I can hear the spurts of data so I assume that its ACSB.

Thanks;
Mil
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Old 12-20-2013, 7:15 PM
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Yes the PSE system is using NFM.

Well, 219-225 here is the 1.25m ham band. Are you sure it's not APRS or packet data?
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Old 12-21-2013, 9:10 AM
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Default MPT-1327

220-222.999 was given to business long ago. The FCC database
has alot of inactive users and a few active ones. One is a
Power company in my area. It seems to be sideband and is
not supported by any of any decoder that I can determine.

Thanks;

Mil
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