USVI MPT-1327 System Info

scannerboy02

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I just got back to the mainland from 10 days in St. John. I took several scanners and my laptop with 4 RTL-SDR's with the hopes of doing as much research on the radio systems on the island as I could. I was in St. John about 7 years ago and only took one scanner with me at that time (not knowing how it would go with security. I had no problems at all) so I came prepared on this trip. Yep I'm a radio nerd, when I go on a Caribbean vacation in the middle of winter I still play with radios.

I stayed in a house at the top of Bordeaux Mountain on the Coral Bay side of the island within walking distance from the radio tower on the mountain, this was the same area as I stayed on my last trip. I know the hurricanes in 2017 took out a lot of the radio towers on the islands including the tower on Bordeaux Mountain that fell and was completely rebuilt. Although I only had one scanner with me on my last trip it seemed like I was able to hear a lot more radio traffic last time than I was able to hear this time, perhaps the loss of radio towers had something to do with this.


As for what I was able to hear,

I used SDRTrunk and 3 of the RTL-SDR's to successfully decode and monitor the "Virgin Island, Government of" MPT-1327 trunking system.
While I was able to audibly hear several control channels I was only able to get the software to decode the control channel for the Bordeaux Mountain site. It's possible I was either too far away from the other sites or too close to the Bordeaux Mountain site and it was interfering with the signals, I was able to hear the Bordeaux site with the antennas taken off of my scanners.

Bordeaux Mountain Site
Site: 20577
Control Channel - 159.1500
Traffic Channel 100 - 156.2400
Traffic Channel 112 - 159.4500
Traffic Channel 113 - 160.2750
Traffic Channel 101 - 157.4500
Traffic Channel 110 - 158.8350
The site assigned the traffic channels in the order listed moving from one channel to the next with each assignment. The sites use message trunking (perhaps all MPT-1327 systems do this?) so the entire conversation could be heard on one channel and some of them were VERY longwinded lasting more than the 60 second timeout I had set in the software.

Talk Groups
002-6000 - VIPD - Could hear calls being dispatched on all three islands.
002-6002 - Unknown - Sounded like possibly a VIPD secondary/talk channel.
002-6009 - Unknown - Possibly same as above.
002-6033 - VI Port Authority - Heard several calls at the airports.
003-6020 - Unknown - Only heard a few mic clicks.
003-6021 - VIEMS - Heard several EMS calls.
003-6022 - Unknown - Only heard a few mic clicks.
003-6025 - Unknown - Only heard a few mic clicks.
003-6035 - VIFS - Heard several Fire Service calls.
003-6036 - Unknown - Possibly a Fire Service secondary/tac channel, heard a VIFS unit told he was on the wrong channel, he then came up on 003-6035.
003-6042 - Unknown - Heard something being referenced to as "good evening radio checks" and a rollcall being conducted.
003-6049 - Unknown - Only heard a few mic clicks.

Of note, I could hear the same traffic I was hearing on the Bordeaux site on several other frequencies likely from other sites.
Here is the channel lineup that I was getting, the same traffic rolled from frequency to frequency at the same times.
156.2400 / 159.2550 / 159.1950
157.4500 / 159.0300 / 159.2100 / 159.0000
158.8350 / 160.6650 / 159.4650 (Could hear a "data" signal on this frequency while the others were transmitting voice)
159.4500 / 159.4350
160.2750 / 159.4650

MPT-1327 control channel signals were heard on
158.2450
158.7650
158.7700
158.8950
158.9700
159.1500 - Bordeaux Mountain
160.2450


Other things heard.
127.7500 - Cyril E. King Airport ATIS
151.3500 - CTCSS 241.8 - Unknown agency radio checks
419.4125 - DCS 051 - Unknown, mic clicks
160.4550 - CTCSS 74.4 - Taxi Service
158.5000 - Radio checks between several area islands and the "EOC"


Additional notes.
Many of the frequencies I heard were either not in the FCC database or not being used as they were licensed in the database. For instance several of the frequencies for the "Virgin Island, Government of" trunking system were not in the database, licensed as conventional or licensed to commercial radio systems. I'm guessing being that they are "out in the middle of the ocean" they are a little loose on the FCC rules.

It also appears from documents I was able to find that they are in the process of upgrading the government radio system to a P25 trunking system. I saw some references to a VHF system and some to a 700 MHz system, I did not hear any P25 signals (or anything else digital) at all.
 
Last edited:

ecps92

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Jul 8, 2002
Messages
11,702
Location
Taxachusetts
419.4125 D-051 has been there for (10+) years, I heard it from St Thomas, likely a Remote downlink from another freq
but never able to narrow it down.

Being down there, the FCC does handle the US but reception from the other islands is easy, so determining who/what is tough

I just got back to the mainland from 10 days in St. John. I took several scanners and my laptop with 4 RTL-SDR's with the hopes of doing as much research on the radio systems on the island as I could. I was in St. John about 7 years ago and only took one scanner with me at that time (not knowing how it would go with security. I had no problems at all) so I came prepared on this trip. Yep I'm a radio nerd, when I go on a Caribbean vacation in the middle of winter I still play with radios.

I stayed in a house at the top of Bordeaux Mountain on the Coral Bay side of the island within walking distance from the radio tower on the mountain, this was the same area as I stayed on my last trip. I know the hurricanes in 2017 took out a lot of the radio towers on the islands including the tower on Bordeaux Mountain that fell and was completely rebuilt. Although I only had one scanner with me on my last trip it seemed like I was able to hear a lot more radio traffic last time than I was able to hear this time, perhaps the loss of radio towers had something to do with this.


As for what I was able to hear,

I used SDRTrunk and 3 of the RTL-SDR's to successfully decode and monitor the "Virgin Island, Government of" MPT-1327 trunking system.
While I was able to audibly hear several control channels I was only able to get the software to decode the control channel for the Bordeaux Mountain site. It's possible I was either too far away from the other sites or too close to the Bordeaux Mountain site and it was interfering with the signals, I was able to hear the Bordeaux site with the antennas taken off of my scanners.



Other things heard.
127.7500 - Cyril E. King Airport ATIS
151.3500 - CTCSS 241.8 - Unknown agency radio checks
419.4125 - DCS 051 - Unknown, mic clicks
160.4550 - CTCSS 74.4 - Taxi Service
158.5000 - Radio checks between several area islands and the "EOC"

Additional notes.
Many of the frequencies I heard were either not in the FCC database or not being used as they were licensed in the database. For instance several of the frequencies for the "Virgin Island, Government of" trunking system were not in the database, licensed as conventional or licensed to commercial radio systems. I'm guessing being that they are "out in the middle of the ocean" they are a little loose on the FCC rules.

It also appears from documents I was able to find that they are in the process of upgrading the government radio system to a P25 trunking system. I saw some references to a VHF system and some to a 700 MHz system, I did not hear any P25 signals (or anything else digital) at all.
 

mam1081

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Dec 19, 2002
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Next to a scanner...
You made a lot more progress than I did last summer there! I circumnavigated St John over a week, but only had a scanner to do some recordings in the evenings. I recorded sites in hex (adding decimal here). With your info, we probably have enough to submit this as a new system (since the Passport didn't seem to be on).

On Site 5061 (20577), I confirmed:
Channel 112 = 159.450
Channel 113 = 160.275
Channel 111 was control (I didn't narrow that down)
159.750 I got as site5061h/20577 also
161.400 might have been on the site too, but I was getting some terrible images on my radio

I heard other frequencies and sites:

158.7300 - didn't get channel #, site 5029h/20521 - adjacent sites 5019h (with control 021) and 5009h (with control 003)
158.8125? - didn't get channel #,site 50c1h/20521
158.7675? - didn't get channel #, site 50c9h maybe
158.8875 - didn't get channel #, site 50A1h/20641 control channel 201
158.9775 - didn't get channel #, site 50B9h/20665. adjacent site = 50A1h
157.5900 - didn't get channel #, site 5011h/20497 - perhaps near Charlotte Amalie water plant? adjacent site = 5009h (using control 003)
158.2425 - channel 216 - control was channel 227
158.9250 - channel 34 - control was channel 32
159.1050 - channel 36 - control was channel 32
159.0300 - channel 22 - control was channel 21 on site 5019h
159.4350 - channel 24 - control was channel 21 on site 5019h
158.8950 - didn't get a channel # control channel 21 site 5019h
159.0900 - channel 13 - control was channel 11
159.3600 - channel 16 - control was channel 11
159.3450 - channel 5 - control was channel 3

I wasn't able to narrow down locations nearly as well as you did (great job on that), but got a lot of channels that I had a hard time digging up licenses for!
 
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