Malicious jamming of Cajundome frequencies

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Tim-B

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Someone is transmitting for several minutes at a time on 453.975 which is one of the Cajundome's frequencies. They transmit a noise that sounds like an engine running. Does anyone in the Lafayette area know how to direction find the source of a signal? I would love to see the perpetrator bend over and take it from behind with a $10,000 FCC fine. This is not appear to be some new digital format they are using as I get static every now and then in the signal and it is using a CTCSS of 173.8 Hz which is the tone they use for their comms on that frequency. If I had some direction finding equipment I would hit the road right now and find they guy and sic the long arm of the federal govt. on him but I do not know how to DF. If anyone in the Lafayette area is up to the task then go get 'im.
 

kb5udf

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458.975

Sounds like you are hearing interference on a repeater output, so to DF (direction find) the culprit, you need
to listen 5mhz up on 458.975. Depending on the power output of the offending signal, direction finding can
be done with very modest equipment, such as an HT only. Basically the principal is to receive the offending signal weakly enough such that if you turn away cover the antena with your hand etc, you attentuate. Wash, rinse and repeat until you get closer. The hard part is narrowing it down further if the signal is strong.
That is, if someone has a 4 watt baofeng, using above methods you will narrow it down, two a neighborhood/a few houses. Eventually, when you are close, you can remove the HT antenna altogether.

DF'ing better than this requires a directional antenna and some type of "box" with variable attentuation.
Obviously, I know you are no fool, but for the record and CYA, I would discourage confronting the culprit yourself.

I would also point out that cajundome has been migrating to DMR I believe, I'll have a listen.
 

Tim-B

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I would never confront him myself but I would pass the information on the FCC enforcement division. I have testified in court numerous times as both a material witness and as an expert witness and I am not afraid to "get involved" as they say. But I will leave the confrontation up to the authorities.
 

kb5udf

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figured

I figured as much Tim, no insult intended, I know you're responsible,that was just the CYA part of my post.

FYI I did confirm per FCC uls that the freq is licensed for DMR. Post an audio clip of the culprit if you can.
 

ecps92

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Sounds like your user has gone DMR along with Analog use
ULS License - Public Safety Pool, Conventional License - WNFA485 - LAFAYETTE, CITY OF - Frequencies Summary
and Based on the FCC License, they are Licensed for MotoTRBO
Emission Designator - The RadioReference Wiki
Someone is transmitting for several minutes at a time on 453.975 which is one of the Cajundome's frequencies. They transmit a noise that sounds like an engine running. Does anyone in the Lafayette area know how to direction find the source of a signal? I would love to see the perpetrator bend over and take it from behind with a $10,000 FCC fine. This is not appear to be some new digital format they are using as I get static every now and then in the signal and it is using a CTCSS of 173.8 Hz which is the tone they use for their comms on that frequency. If I had some direction finding equipment I would hit the road right now and find they guy and sic the long arm of the federal govt. on him but I do not know how to DF. If anyone in the Lafayette area is up to the task then go get 'im.
 

Tim-B

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Okaaaay - what I am hearing sounds an awful lot like the NEXEDGE sample on the website I linked to above. However - the transmissions sometimes last for several minutes and not the five or ten seconds that they normally talk and I am stil hearing their normal day to day and getting ready for tonight's concert type analog traffic on the same frequency. And if this is a legitimate digital mode I should not see the analog PL tone transmitted at the same time. I think it is some fool deliberately playing a recording in analog mode on their frequency and PL tone so they hear it.
 

kb5udf

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Trunking?

FYI many scanners can display false indications of PL tone. Not saying that's happening here, but
it does happen to me often, with various scanner types. Also, it could be possible they are deploying
some type of trunking. Some of the DMR systems do have a control channel. For example Stuller Settings does this wherein one of the UHF frequencies will be continously active for a time with the control channel, but it rotates.

I'll be in the home office/shack in a few, and I'll give it a listen.
 

Tim-B

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That could be it. Since the 536 can't do NXDN then that is probably why it is listening to it in analog mode. But, on the other hand I have the frequency in two different favorites lists. One list is for all DMR licensed frequencies in Lafayette Parish and it is set to digital mode and search for NAC or color code and the other is set as analog mode to only open squelch on the proper PL tone. The analog one with the PL tone entered is opening squelch and monitoring the weird transmissions. Soooooo, I don't know what is happening.

I normally hear them on 453.55 with a CTCSS of 141.3 and on 453.975 with a CTCSS of 173.8.
 

ecps92

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Which is why many folks report 67.0 Hz on P25 :D


FYI many scanners can display false indications of PL tone. Not saying that's happening here, but
it does happen to me often, with various scanner types. Also, it could be possible they are deploying
some type of trunking. Some of the DMR systems do have a control channel. For example Stuller Settings does this wherein one of the UHF frequencies will be continously active for a time with the control channel, but it rotates.

I'll be in the home office/shack in a few, and I'll give it a listen.
 

Tim-B

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No, it comes and goes. The signal is very strong and clear when I do hear it and it sometimes stays on for a few minutes they cuts off. I heard one employee call for another one on analog then the sound came back for a minute or so then when it stopped the employee who was being called answered the one calling him on analog. So it does not sound like it belongs to them.
 

kb5udf

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Repeater problem

Heard it, sounds like an oscillation/feedback loop of some sort. Alot of odd noise and a ton of reverb. I think its a problem with the repeater.
 

Tim-B

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I just heard them say that they were having trouble with the repeater. So that's what it was. Oh well, looks like I won't be doing a fox hunt.
 
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