interesting federal data bursts

[mancow]

Same thing in the Kansas City area. I assume it's some sort of link system as many repeaters seem paired.

 

[batdude]

this is what i am thinking.... i am becoming convinced there is a much larger effort in place than "vote-scanning". I think this is an effort to link multiple repeater sites, across agencies....

 

[ecps92]

My experience [monitoring] is that most Vote-Scan sites are linked for Wide-Area coverage.
a. Common input Freq and NAC for the Wide-Area Vote-Scan - where we see the beacons occur periodically
b. But also have a Unique NAC for "Local Only - aka One Repeater" on the same input

this is what i am thinking.... i am becoming convinced there is a much larger effort in place than "vote-scanning". I think this is an effort to link multiple repeater sites, across agencies....

 

[batdude]

My experience [monitoring] is that most Vote-Scan sites are linked for Wide-Area coverage.
a. Common input Freq and NAC for the Wide-Area Vote-Scan - where we see the beacons occur periodically
b. But also have a Unique NAC for "Local Only - aka One Repeater" on the same input

i have never seen any of the monitored freqs i posted use anything other than the "normal" NAC listed for the repeater. Not saying that your theory isn't plausible.... i just have not observed that activity on these pairs.

 

[sflmonitor]

ecps92 is correct. There are some federal systems (including some here in Florida) that use NAC steering to allow users to select either wide-area/linked repeaters or standalone/single repeaters. This is normally done by programming different NACs in the repeater input frequency. The repeater output frequency will have the same NAC in either mode.

 

[ecps92]

I think you missed the comment about input which is the key item

Note, all this information is fictional and made up as an example [don't try this at home]
Repeater A 172.8625 $200
Repeater B 172.7750 $200
Repeater C 172.7125 $200
Repeater D 169.6000 $200
Repeater F 163.7500 $200

All using 162.7250 $201 for the Vote-Scan input for the Wide-Area Coverage

However each Repeater has the same Freq input, but a different NAC for LOCAL access, not going across the other repeaters.
The Output NAC remains the same, we as Scannists [err Casual monitors] don't even notice

So Local Access is
Repeater A 172.8625 $200 / 162.7250 $20A
Repeater B 172.7750 $200 / 162.7250 $20B
Repeater C 172.7125 $200 / 162.7250 $20C
Repeater D 169.6000 $200 / 162.7250 $20D
Repeater F 163.7500 $200 / 162.7250 $20E

Since we many never be close enough to the Operation the input is never caught/mentioned/reported.

Same situation we have had for years with CBP and ATF when folks report DNET-01 or NET-01 routinely
when the input freq/tone is important and we then really find out it is DNET 3, 6, 17, 39, 40, 43, 47, 52, 55, 57, 58, 59, 60-65 or 69

to steal off of a catch phrase on the sad years

"Input Lives Matter"

i have never seen any of the monitored freqs i posted use anything other than the "normal" NAC listed for the repeater. Not saying that your theory isn't plausible.... i just have not observed that activity on these pairs.

 

[DeepBlue]

I've always had a sense these agencies were setting themselves up for collisions on the air when local and wide area users both need the same freq. Same happens in DMR on the Amateur repeaters here. Despite having hundreds of routing options, people forget you really only get one user per frequency at a time. This is especially dicey when you only hear the NAC or in DMR, the color code/slot you are listening to, as a user.

Just an observation.

S.

 

[K5MPH]

The data burst could be for control channel use.

 

[IcomIcR20]

My two nearby VHF P25 conventional repeaters used by a Fire and Police Department makes similar data bursts when it is inactive. It’s seemingly random when the burst happens and the length of the burst varies. The repeaters are in two different states but behave quite similarly to what you are describing.

 

[ecps92]

Generally these "Wide Area' are limited to a Field Office or Resident Agent Office so they know who is using them in the area
and if needed will assign a second net for conflicting area of Ops.

I've always had a sense these agencies were setting themselves up for collisions on the air when local and wide area users both need the same freq. Same happens in DMR on the Amateur repeaters here. Despite having hundreds of routing options, people forget you really only get one user per frequency at a time. This is especially dicey when you only hear the NAC or in DMR, the color code/slot you are listening to, as a user.

Just an observation.

S.

 

[d119]

This could be a part of the very strange Integrated Wireless Network (IWN) that Federal agencies use. I occasionally do work at sites that have IWN equipment at them, and without getting into any detail, as it's not appropriate, they are very, very strange systems that are configured unlike anything I've ever seen before. They are in the aforementioned VHF spectrum, and I see TX keyup bursts on the front panels of the things occasionally.

 

[prc117f]

170.2865 Does not sound like P25 or securenet, some kind of occasional databurst. It is at most 1 second when it occurs and its random.

 

[ecps92]

.2865 is not valid

And where are you hearing it, since Frequencies do/will get used by a variety of agencies in different regions it helps to not where it was heard and/or update your profile

170.2865 Does not sound like P25 or securenet, some kind of occasional databurst. It is at most 1 second when it occurs and its random.

 

[nd5y]

If it's 170.2875 it could be
https://wiki.radioreference.com/index.php/Hydrological/Meterological_Channels
If it's a non-federal user sending the data bursts then there should be an FCC license.

 

[IcomIcR20]

Yes, 170.2875 is licensed to several users such as: "South Florida Water Management District", "MOHAVE COUNTY FLOOD CONTROL DISTRICT," etc. That could very well be the data bursts you were hearing,

 

[ecps92]

Yup, IFLOWS
https://www.nws.noaa.gov/om/water/resources/Flood_Warning-Systems_Manual.pdf

If it's 170.2875 it could be
https://wiki.radioreference.com/index.php/Hydrological/Meterological_Channels
If it's a non-federal user sending the data bursts then there should be an FCC license.

 

[DeepBlue]

Generally these "Wide Area' are limited to a Field Office or Resident Agent Office so they know who is using them in the area
and if needed will assign a second net for conflicting area of Ops.

This all sounds plausible however, if you aren't listening to the entire system, one would possibly not know they were experiencing collisions since they just hear nothing in that case.

S.

 

[ecps92]

They would hear the traffic as it comes across the entire Zone / Set of Frequencies

This all sounds plausible however, if you aren't listening to the entire system, one would possibly not know they were experiencing collisions since they just hear nothing in that case.

S.

 

[DeepBlue]

They would hear the traffic as it comes across the entire Zone / Set of Frequencies

Only if they are listening to every NAC (or wildcard). If they are only listening to specific ones they would naturally only hear valid complete packets coming through but during collisions that wouldn't be the case. They would have to be voted so only one system at a time gets the frequency even across departments, etc. Only using one frequency for multiple departments and locations especially if they are separated out by NAC is a bad idea. Like kids at a campground all using FRS radios with their own PLs. Either some controller doles out the channel availability or there are collisions and intelligibility issues. In a mass issue needing those multiple departments to be on the air at the same time, this is a bad thing. This is for single channel systems I am talking about, or limited frequencies. It's simply a maximum capacity issue. I see what you are syaing, in a multi frequency system with s controller, sure.

S.

 

[ecps92]

No Controller, we are talking Conventional systems, not a TRS

No multiple NAC's as they all use the same NAC output [In my monitoring experience], input NAC may/maynot vary

Multiple Dept's ? - You understand this is a Federal Forum

Re-Read post #23

Only if they are listening to every NAC (or wildcard). If they are only listening to specific ones they would naturally only hear valid complete packets coming through but during collisions that wouldn't be the case. They would have to be voted so only one system at a time gets the frequency even across departments, etc. Only using one frequency for multiple departments and locations especially if they are separated out by NAC is a bad idea. Like kids at a campground all using FRS radios with their own PLs. Either some controller doles out the channel availability or there are collisions and intelligibility issues. In a mass issue needing those multiple departments to be on the air at the same time, this is a bad thing. This is for single channel systems I am talking about, or limited frequencies. It's simply a maximum capacity issue. I see what you are syaing, in a multi frequency system with s controller, sure.

S.