Does anyone know if there is a MPT1327 system in SoCal that is operating on the 216-222 MHz band? I am hearing what sounds like a control channel on 217.925. There are lots of comms down in that freq range and seems to be trunking because I do not get any CTCSS/DPL tones and the conversations can go from English to Spanish, so there are multiple users.
Anyone know about the MPT1327 system in SoCal?
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madnachos
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I am in Huntington Beach and I get the signal on 217.9250 really strong from here.
Have you tried the MPT decoding software yet?
Could it be related to these guys? "Roamer One Inc."
http://www.wirelessweek.com/article/CA4826.html?spacedesc=
I've found control channels on 217.6225 Mhz and 220.5325 Mhz in Marin County where I live here in the SF Bay Area, both licensed to Roamer One Inc. The one on 217 has a high pitched sound very similar to the MPT1327 Control Channel on the "digital modes samples" web page, while the one on 220 has a much lower sound to it. But I got no results when running the latest UniTrunker on either one.
Refering to this article, it sounds like they use something called the advanced digital network trunking (ADNT) protocol, which is BASED on MPT1327 but has additional features. That might explain why Unitrunker didn't decode the control channels I found.
http://mrtmag.com/mag/radio_news_31/
I've attached zip files with recordings of the two control channels through the discriminator tap on my scanner. Brandon, is this comprable to what you're hearing or entirely different? Does anyone know more about the type of trunking protocol in these recording (such as ADNT, if indeed that's what it is)?
Thanks!
-Inigo
http://www.wirelessweek.com/article/CA4826.html?spacedesc=
I've found control channels on 217.6225 Mhz and 220.5325 Mhz in Marin County where I live here in the SF Bay Area, both licensed to Roamer One Inc. The one on 217 has a high pitched sound very similar to the MPT1327 Control Channel on the "digital modes samples" web page, while the one on 220 has a much lower sound to it. But I got no results when running the latest UniTrunker on either one.
Refering to this article, it sounds like they use something called the advanced digital network trunking (ADNT) protocol, which is BASED on MPT1327 but has additional features. That might explain why Unitrunker didn't decode the control channels I found.
http://mrtmag.com/mag/radio_news_31/
I've attached zip files with recordings of the two control channels through the discriminator tap on my scanner. Brandon, is this comprable to what you're hearing or entirely different? Does anyone know more about the type of trunking protocol in these recording (such as ADNT, if indeed that's what it is)?
Thanks!
-Inigo
madnachos
Member
Your recording on 217Mhz sounds like what I here on 217.9250.
Yeah the first recording sounds like it alright.
Funny thing is UniTrunker decodes when I put it on the control channel freq.
Here are some screenshots...
Group ID
Radio ID
I don't know a thing about MPT1327 systems so I have no idea if this is accurate but at least its something. Still need to figure out the channel lineup. Here are the 217 MHz channels I have logged voice activity on... some might be unrelated but who knows. Seems to be some towing and taxis using the system.
217.875 - English and Spanish : weird data burst at end of transmission
217.350
217.425 - mention of address in Pomona
217.800 - English and Spanish : weird data burst at end of transmission
217.050 - English and Spanish : weird data burst at end of transmission
217.200
217.750 - English and Spanish : weird data burst at end of transmission
217.725 - English and Spanish : weird data burst at end of transmission
The weird thing is whenever there is activity in UniTrunker, it doesn't seem to key up very long on this system. But it definitely shows data and activity.
Funny thing is UniTrunker decodes when I put it on the control channel freq.
Here are some screenshots...
Group ID
Radio ID
I don't know a thing about MPT1327 systems so I have no idea if this is accurate but at least its something. Still need to figure out the channel lineup. Here are the 217 MHz channels I have logged voice activity on... some might be unrelated but who knows. Seems to be some towing and taxis using the system.
217.875 - English and Spanish : weird data burst at end of transmission
217.350
217.425 - mention of address in Pomona
217.800 - English and Spanish : weird data burst at end of transmission
217.050 - English and Spanish : weird data burst at end of transmission
217.200
217.750 - English and Spanish : weird data burst at end of transmission
217.725 - English and Spanish : weird data burst at end of transmission
The weird thing is whenever there is activity in UniTrunker, it doesn't seem to key up very long on this system. But it definitely shows data and activity.
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Beautiful! CRAP though because I still can't get that identical control channel up here on 217.6225 to decode in Unitrunker 10. 
WAIT - It just must be a far away system. I adjusted the location of the scanner and I'm getting it between 2%-10% decode. No voice channels, affiliations, groups or users yet. But I did get the SysID, and that's a start. It's MPT1327 SysID: 4091.
Wayne, would you consider trying 217.6225 Mhz and see if you recieve any MPT1327 control channel from over there in Livermore?
EDIT: I went simple and tried the vbtrunk.exe program and it's decoding all the BCAST messages fine, just no system voice activity yet.
No voice channels, affiliations, groups or users yet. But I did get the SysID, and that's a start. It's MPT1327 SysID: 4091.Wayne, would you consider trying 217.6225 Mhz and see if you recieve any MPT1327 control channel from over there in Livermore?
EDIT: I went simple and tried the vbtrunk.exe program and it's decoding all the BCAST messages fine, just no system voice activity yet.
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Brandon, after reading up on MPT1327 a little bit, I'm going to take a stab at your system. Here's what I used:
http://wiki.radioreference.com/index.php/MPT-1327
http://www.tarapippo.net/mpt1327/MPT1327.html
http://www.linato.net/trunkview/?How_to_find_base_frequency
First, I wanted to figure out the base frequency using the Control Channel:
Knowing the Base Freq and the Step Size (assuming it checked out with your known freqs, which it did), I could go back and find the freqs for the other LCNs using this method:
Here's what I found using that method:
LCN 58 - 217.8500 Mhz
LCN 60 - 217.8750 Mhz
LCN 63 - 217.9125 Mhz
LCN 64 - 217.9250 Mhz (Your Control Channel)
LCN 70 - 218.0000 Mhz
After confusing myself with algebra for a little while, I was able to figure out that:
MPT-1327 supposedly has a weird databurst at the beginning and ending of all the voice transmissions, so trying this formula on your other databurst freqs, I got:
217.725 = LCN 48
217.750 = LCN 50
217.800 = LCN 54
The others may be from other systems (such as 217.05, which is below the Base Freq), or may be conventional freqs (any CT or DC tones?) or in other trunking formats.
Give those a try and let me know whether I'm spot on or totally off, in which case it will be back to square one (and figuring out a new step size). But I'm encouraged one of the freqs you heard voice on coorelates to an LCN # in your unitrunker screenshot, and 3 more freqs could POTENTIALLY be in there given the base freq I found.
Haha learning a new trunking system is exciting, let me know how it works out!
http://wiki.radioreference.com/index.php/MPT-1327
http://www.tarapippo.net/mpt1327/MPT1327.html
http://www.linato.net/trunkview/?How_to_find_base_frequency
First, I wanted to figure out the base frequency using the Control Channel:
Knowing the Base Freq and the Step Size (assuming it checked out with your known freqs, which it did), I could go back and find the freqs for the other LCNs using this method:
Here's what I found using that method:
LCN 58 - 217.8500 Mhz
LCN 60 - 217.8750 Mhz
LCN 63 - 217.9125 Mhz
LCN 64 - 217.9250 Mhz (Your Control Channel)
LCN 70 - 218.0000 Mhz
After confusing myself with algebra for a little while, I was able to figure out that:
MPT-1327 supposedly has a weird databurst at the beginning and ending of all the voice transmissions, so trying this formula on your other databurst freqs, I got:
217.725 = LCN 48
217.750 = LCN 50
217.800 = LCN 54
The others may be from other systems (such as 217.05, which is below the Base Freq), or may be conventional freqs (any CT or DC tones?) or in other trunking formats.
Give those a try and let me know whether I'm spot on or totally off, in which case it will be back to square one (and figuring out a new step size). But I'm encouraged one of the freqs you heard voice on coorelates to an LCN # in your unitrunker screenshot, and 3 more freqs could POTENTIALLY be in there given the base freq I found.
Haha learning a new trunking system is exciting, let me know how it works out!
Just as I was going to say it's dead quiet it broke squelch. It's barely readable though. Propagation seems similar to sites on the peninsula as I drive around.inigo88 said:
At the moment I'm getting another CC on 217.5125 at about S-1 to S-2. I know there's nothing close to me. I think if there were any nearby it would be Vollmer/Grizzley. Doesn't seem like anything from Monument or Diablo.
Wayne
I'm getting it here in Hayward S6. Wish I could decode it.
vince48
I'm getting it here in Hayward S6. Wish I could decode it.
vince48
Wayne, despite the low decode rate on UniTrunker, I have a feeling the 4091 system on 217.6225 is very local to me. It decodes fine in this TrunkSnort program, and the propogation of the signal sounds identical to another control channel on 220.5325 - this is the lower sounding one that cycles at the same rhythm as the MPT1327 CC but has a much lower tone to it (see my zipped wav file of it earlier in the thread - perhaps this mystery proprietary MPT-based "ADNT" protocol?). While I can't find ULS licenses for any of the 217 freqs, 220.5325 is licensed WPBN298 to Roamer One Inc. at Big Rock Ridge in Novato, so I figure these systems may be co-located there.
I wish I'd get a Go To Channel message though already so I can start figuring out freqs!!! I've run TrunkSnort (vbtrunk.exe) on 217.6225 Mhz for about a day and all it's giving me is:
And it just continues with lines and lines of BCAST messages thru the CCh but no system voice activity. Bummer! I'll keep at it though.
Vince, I used this link to get started:
http://www.tarapippo.net/mpt1327/MPT1327.html
I use Unitrunker and love it, but in this case I had trouble with getting Unitrunker to decode anything. I used the simpler program from that link, TrunkSnort, to at least be able to watch the control channel activity. If your system has any voice activity it should say "GTC" for a couple of lines meaning "Go To Channel", and tell you the Logical Channel Number (LCN), along with the LCN of the Control Channel when it tells the radios to go back to it (if I understand MPT1327 correctly). At that point you'll be able to start doing the math to map out the channel assignments like I demonstrated in the above post. I'm using a cable plugged from a discriminator tapped scanner to my line in port on my sound card, but you may be able to get away with using the Headphone Jack if you don't have a tapped scanner. In any case, it'd be nice to see anyone having better luck with more active systems than I am with mine.
Good luck!
-Inigo
I wish I'd get a Go To Channel message though already so I can start figuring out freqs!!! I've run TrunkSnort (vbtrunk.exe) on 217.6225 Mhz for about a day and all it's giving me is:
And it just continues with lines and lines of BCAST messages thru the CCh but no system voice activity. Bummer! I'll keep at it though.
Vince, I used this link to get started:
http://www.tarapippo.net/mpt1327/MPT1327.html
I use Unitrunker and love it, but in this case I had trouble with getting Unitrunker to decode anything. I used the simpler program from that link, TrunkSnort, to at least be able to watch the control channel activity. If your system has any voice activity it should say "GTC" for a couple of lines meaning "Go To Channel", and tell you the Logical Channel Number (LCN), along with the LCN of the Control Channel when it tells the radios to go back to it (if I understand MPT1327 correctly). At that point you'll be able to start doing the math to map out the channel assignments like I demonstrated in the above post. I'm using a cable plugged from a discriminator tapped scanner to my line in port on my sound card, but you may be able to get away with using the Headphone Jack if you don't have a tapped scanner. In any case, it'd be nice to see anyone having better luck with more active systems than I am with mine.
Good luck!
-Inigo
I have been monitoring a new system in CT and have a couple tips. For my system here, Unitrunker likes the speaker audio better than the discriminator audio. I am not sure why but it does. There is another MPT1327 program (free) called Trunkview.
http://www.linato.net/trunkview/
chris
http://www.linato.net/trunkview/
chris
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Its a company called "AccessSpectrum". The system changed hands a number of times prior to its present ownership. Their web page is www.accessspectrum.com
- Rich W7KI
www.socaltvradio.com
- Rich W7KI
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