451.49375 IDAS

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W1KNE
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451.49375 IDAS

Post by W1KNE »

Hearing constant data "pulses" followed by the occasional conversation on TG 1-80, which sounds like a transportation company.

Heard the other week comms about "going into Waltham". Today heard comms about coming from a body shop.

All has been quite strong here in Taunton. Bill picked it up in Weymouth as well, but not as strong.

FCC has nothing on this frequency.
Mike Fitzpatrick
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Re: 451.49375 IDAS

Post by ecps92 »

I thought it would have been 451.5000 [using a Scanner for DMR] but it could be .49375
W1KNE wrote: 03 May 2021 13:26 Hearing constant data "pulses" followed by the occasional conversation on TG 1-80, which sounds like a transportation company.

Heard the other week comms about "going into Waltham". Today heard comms about coming from a body shop.

All has been quite strong here in Taunton. Bill picked it up in Weymouth as well, but not as strong.

FCC has nothing on this frequency.
Bill Dunn N1KUG
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Re: 451.49375 IDAS

Post by W1KNE »

Definitely on .49375, it won't decode on .5000.
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Re: 451.49375 IDAS

Post by garys »

I'm getting a strong pulse signal here in Stoughton. I'll sit on it for a couple of days and try to get an idea of the users.

Eric has a good post over at RR http://forums.radioreference.com/thread ... ng.298002/ on different types of IDAS. Based on his post this seems like it is a Single Site system. DSDPlus IDs it at IDAS TB.

I've set the Band Width in DSDPlus to 4 and I'll see how the decoding is.

451.5000 is part of the Gillette Stadium "Operations" Cap+ system.
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Re: 451.49375 IDAS

Post by garys »

1-80 and 1-90 active today. 1-90 discussion about an accident on I-95 south, but no location.
Both TGs seem to be the same operation.

To add to the mystery, there is also a "Channel 4" showing up on the frequency. I don't know enough about IDAS to know if that means there's another frequency that's missing from our view or what.
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Re: 451.49375 IDAS

Post by garys »

My last update for now. Here is what I have up to now.

DSDPlus identifies three channels, 1, 4, 5. 451.49375 is Channel 1, the other two are unknown as of now.

I have heard TGs 1-75, 1-80, 1-90. From reading Eric's post at RR, it seems that these systems use an LTR type TG structure. x is the "home channel" then the other number is the actual TG. I haven't figured out the UID structure yet.

The control channel beacons at longer intervals than Cap+, more like LTR systems.

I have this system set up in DSDPlus as follows,

IDAS 0.1, 1, 451.49375, 0.0, 0
IDAS 0.1, 4, xxx.xxxxx, 0.0, 0
IDAS 0.1, 5, xxx.xxxxx, 0.0, 0

Note that DSDPlus will through an error message if you put Xs in the frequency field so I have those last two channels remarked out.

I'm stuck now as without FCC data it's going to be a needle in a haystack chase to figure out those other two channels. Unlike NXDN systems, there are no hints in the channel number. Unless someone has an idea on formulas that is.

Maybe Eric will jump in with some insights.
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Re: 451.49375 IDAS

Post by garys »

1-80 appears to be a tow company. They might do the initial dispatch by text, because I never hear that. They do updates over the radio. Today, they mentioned something on I-95 near Route 3, which is in Burlington.

Also, they are on the air at all times of the day and night, which tow companies share with ambulance services.

1-75 is also on at random hours and 1-6 is on weekends more than week days.

It's a PITA that there is no license for this.
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Re: 451.49375 IDAS

Post by ecps92 »

Initially had thoughts of Maine with a band openning ,but decided to try this one again this week
Not a Busy Company after two days only 4 transmissions

But it is R9 into Weymouth/Rockland/Hingham and no band openning today for UHF
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Re: 451.49375 IDAS

Post by ecps92 »

Updates - this appears to be part of a TRS

Ch.1 is 451.49375

There is also a Ch.2, 4 and 5
as they appear in the DSD+ console when they are using the other frequencies in rotation

Additional TG's 1-75, 1-6

Locations mentioned today are Salem,. Watertown (1-75)
based on the Conversation it may not be Tow Co's but a Concrete Delivery
as they were talking about being the X truck in line

Thinking this is
https://wireless2.fcc.gov/UlsApp/UlsSea ... =&x=10&y=4

going to sit on each frequency +/- for the next few days, see what appears
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Re: 451.49375 IDAS

Post by garys »

My notes have Channel 4 as 451.6875, although I don't think that's verified. It's been a while since I listened to this system. I show Channel 1, 4, and 5, but haven't seen a Channel 2 as of yet.

From the notes, it's received well in Stoughton. It "beacons" about every 5 seconds or so.

I've been checking the FCC website periodically for 451.49375 without any local results. There are a total of nine licenses across the country that contain that frequency.
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Re: 451.49375 IDAS

Post by ecps92 »

451.6875 I likely will never get from here, as that is the JetBlue TIII

I'm wondering if you actually are getting 451.69375
based on the 451.49375 [451.5000]
garys wrote: 01 Jun 2022 12:30 My notes have Channel 4 as 451.6875, although I don't think that's verified. It's been a while since I listened to this system. I show Channel 1, 4, and 5, but haven't seen a Channel 2 as of yet.

From the notes, it's received well in Stoughton. It "beacons" about every 5 seconds or so.

I've been checking the FCC website periodically for 451.49375 without any local results. There are a total of nine licenses across the country that contain that frequency.
Bill Dunn N1KUG
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Re: 451.49375 IDAS

Post by garys »

It could be anything. I'll check the FCC website and see if there are any licenses for 451.69375.

451.49375 is close enough to one of the Gillette trunk frequencies that they sometimes interfere with each other on DSDPlus.
ecps92 wrote: 01 Jun 2022 13:21 451.6875 I likely will never get from here, as that is the JetBlue TIII

I'm wondering if you actually are getting 451.69375
based on the 451.49375 [451.5000]
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Re: 451.49375 IDAS

Post by ecps92 »

Thinking this is it
https://wireless2.fcc.gov/UlsApp/UlsSea ... =&x=18&y=8
likely a slight drift vs using 6.25 freqs
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Re: 451.49375 IDAS

Post by garys »

It's certainly worth a try.
ecps92 wrote: 01 Jun 2022 14:16 Thinking this is it
https://wireless2.fcc.gov/UlsApp/UlsSea ... =&x=18&y=8
likely a slight drift vs using 6.25 freqs
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Re: 451.49375 IDAS

Post by garys »

I must be doing something with my DSDPlus.frequencies listing for this.

I have,

IDAS, 0.1, 0, 1, 451.49375, 0.0, 0
IDAS, 0.1, 0. 4, 451.693 75, 0.0, 0

The DSD+ CC Channel Activity window shows channels 1, 4, 5, but not frequencies entered. I see some channel activity, but nothing happens on the DSD+ VC side.

I have Synthesize All Digital Voice turned on on DSD+ CC window, but get no voice.

I was getting voice last year when we tried to figure this out.

I don't know that I changed any of the information in the .frequencies page.

Anyone have any ideas?
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Re: 451.49375 IDAS

Post by bfrederi »

I got interested in this project in June, and after getting distracted several times, finally took some time today to compile my recordings and DSD+FL logs.

Unfortunately, I don't have any breakthroughs or revelations but can add my observations to what others have already contributed:

I've seen the same talk groups that others have logged, but have a little different take on at least one of them.

1-6: This has been the most active, and there is a lot of highway chatter between drivers. I think Bill is heading in the right direction with concrete delivery. That or gravel or asphalt or all of the above. Although there have been mentions of Waltham and the Lexington rest area on I-95, the most interesting catch was a discussion of how Aggregate Industries in S. Dennis is only 16 minutes from the job in Eastham.

1-75: Very little activity. One exchange included "I'm hauling gravel right now". But doesn't sound like it's related to 1-6.

1-80: It could be the suggested towing company, but it sounds to me more along the lines of delivery/courier/taxi. Many references to locations in Arlington, Lexington, Winchester (including WPD) and one Walpole. As Gary has noted, there is never any dispatch traffic, just the driver reporting completion and getting the okay to return. One interesting exchange: We need to charge $35 because it's been 20 minutes.

1-90: Very little traffic. Just something like "hey joe, are you on the air?"

I see that 451.69375 has already been suggested as a second channel. I had the idea that the distinctive 10 second beacon of 451.49375 might be an interesting signature to look for on the SDR display, and indeed 451.69375 stood out after a few minutes of watching the waterfall. And it does have a similar sound/feel, and DSD+ identified Ch 1 immediately, and then slowly added 3, 8, and 9, the same way .49375 builds up 1, 4, 5. The only TG I've seen there is 1-100 which sounds like a ride service or student shuttle. But there has been absolutely no overlap of traffic between .49375 and .69375.

One other thing: has anybody else noticed that if you run DSD+ long enough on a system, it starts to add additional channels and TGIDs that look spurious?

I'm going to pursue my beacon strategy and see if I see anything similar to .49375 outside the original SDR limits I used.

FWIW.
Bruce, KA1FGY
Burlington, MA
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