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Intentional repeater jamming and how to deal with it

repeater jamming repeater jamming

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#1 WRAK968

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Posted 22 September 2020 - 04:40 PM

Good afternoon/evening everyone. Hoping your Tuesday has gone well.

 

This afternoon I experienced my first intentional jamming incident on the repeater. It started as a few key-ups, however when my father asked if I was calling, this unknown individual chose to hold down the transmit button without speaking. They did this for 30 seconds, than a minute, then 5 minutes, then for 20 (Im sure their transmitter is toast now.) At first I suspected that maybe something was wrong on the RX side of the repeater, so I tuned my portable to the repeaters input frequency, and sure enough there was a signal. So my first action was to jump into my SUV and try to track it. I could clearly receive the signal from inside of my house on a portable, so the transmitter couldn't be too far away.  Using both the truck radio and the portable I tracked it to a house about 4 blocks away where a group of young adults were standing in the driveway laughing. I could see an antenna on the pick-up in the driveway and one of them was holding what looked to be a portable radio. At that location, my portable was receiving a clear signal without an antenna and while laying next to my leg. As I drove by, they saw my vehicle and me looking at them and they panicked. By the time I drove around the block, they had removed the antenna from the roof of the pick-up, and all had gone inside, looking out a window for me, and they stopped transmitting.


Now, I would not recommend confronting anyone about radio jamming. There are too many crazy's in the world and really its not something to get shot over. I slowed in front of the house, and acted like I was taking down information, then drove away just to scare them a bit.

Upon getting home, I removed the access codes from the MyGMRS listing. (Its odd they just tuned directly to the DPL I set for the repeater) and over the next day or two I will begin changing the access tones for the repeater. I may even use a split tone just to reduce the likelihood of this happening again.

 

Then I got curious, I wondered what other repeater owners have done during a jamming situation to protect their equipment and stop the jammers from getting in.

 

So to repeater owners out there, have you ever experienced jamming and how did you handle it?



#2 WRAK968

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Posted 22 September 2020 - 04:41 PM

Also for the record, this was the site with the issue:
https://mygmrs.com/view?id=3027



#3 wayoverthere

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Posted 22 September 2020 - 04:54 PM

I wonder if it's worth reporting to fcc.

https://consumercomp...t_form_id=38844

#4 kidphc

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Posted 22 September 2020 - 05:04 PM

They probably got scared when he did the drive by. If it happens again then yup I would report it. Personally, I wouldn't change a thing. Just to promote it happening again. When it does just have a buddy drive by in a black tahoe/suburban. Make sure to slap as many mag mounts on it before it drives by.

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#5 WRAK968

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Posted 22 September 2020 - 05:40 PM

Overthere, I can't prove they were the ones doing it, just coincidence for the most part, though I would say I am 99% sure. Most times the FCC wont get involved anyways.



 


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#6 mbrun

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Posted 22 September 2020 - 05:51 PM

Great job tracking them down, and keeping a level head and avoiding the confrontation.

If it occurs again, and you have similar luck tracking them down once again, get photos (if possible), license plate information and address info to share with FCC.

Amateur’s also have an official FCC sanctioned group that specializes in such tracking. If you have ham friends, perhaps one of them could help to engage the local tracking team to help. It could be fun for them, and their word/work carries weight.

Michael
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#7 WRAK968

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Posted 22 September 2020 - 05:59 PM

Great job tracking them down, and keeping a level head and avoiding the confrontation.

If it occurs again, and you have similar luck tracking them down once again, get photos (if possible), license plate information and address info to share with FCC.

Amateur’s also have an official FCC sanctioned group that specializes in such tracking. If you have ham friends, perhaps one of them could help to engage the local tracking team to help. It could be fun for them, and their word/work carries weight.

Michael
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The ham community is how I learned to fox hunt (the official term for it) Been a ham for 11 years now :)

If I had known I was gonna locate them as fast as I did I would have had camera ready but I didnt, at least I now know where they are so if it does happen again I can roll by with a camera running.



#8 mbrun

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Posted 22 September 2020 - 06:16 PM

The ham community is how I learned to fox hunt (the official term for it) Been a ham for 11 years now :)

If I had known I was gonna locate them as fast as I did I would have had camera ready but I didnt, at least I now know where they are so if it does happen again I can roll by with a camera running.


Makes sense, and nice job.

I am a new General myself and learned about the group in my studies. Sounds like something I could have fun doing as well. I would love to undergo the training.

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#9 WRAK968

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Posted 22 September 2020 - 06:47 PM

Makes sense, and nice job.

I am a new General myself and learned about the group in my studies. Sounds like something I could have fun doing as well. I would love to undergo the training.

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Its fun if you can afford the equipment, or if the target is easy and stays in one spot. It becomes harder when you cant spend $100 for a yagi and a dedicated radio/signal indicator. The pros use 5 antennas and a special computer which can tell them the direction and strength of the signal and even then you need to take several readings from an area and get several bearings before you get a good idea of where the signal is coming from. Its a bit out of budget for me though, even if I would enjoy doing it.



#10 Lscott

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Posted 22 September 2020 - 07:51 PM

Here are some suggestions from somebody who had similar problems. http://www.repeater-...7pp/art005.html

#11 WRAK968

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Posted 23 September 2020 - 05:34 AM

Here are some suggestions from somebody who had similar problems. http://www.repeater-...7pp/art005.html

That was a good read and I agree about not confronting anyone. My goal was to at very least get a location to know where it was coming from and to do some research into what I was dealing with. Could have been a kid who didn't know what they were doing, or some adult who was annoyed he cant play radio with others. Figuring out what I'm dealing with helps determine how I should handle the situation. Do I replace the codes? Do I report an active license as an abuser? Do I do nothing? The more info I gather, and if the situation repeats on a regular basis, I will end up taking other actions to stop the jammer.



#12 Lscott

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Posted 23 September 2020 - 07:26 AM

That was a good read and I agree about not confronting anyone. My goal was to at very least get a location to know where it was coming from and to do some research into what I was dealing with. Could have been a kid who didn't know what they were doing, or some adult who was annoyed he cant play radio with others. Figuring out what I'm dealing with helps determine how I should handle the situation. Do I replace the codes? Do I report an active license as an abuser? Do I do nothing? The more info I gather, and if the situation repeats on a regular basis, I will end up taking other actions to stop the jammer.

I see you're also a Ham so maybe the local club have a few guys that are into Fox Hunting with the required direction finding gear. Repeater jamming is something they take seriously since it does require a significant investment in time, money and equipment to put a repeater in operation. 

 

Some of the better equipped guys have Doppler direction finding equipment. The jammer only has to be on the air for a very short time to get a fix. I've seen a few using the system below.

 

http://www.kn2c.us/

 

Also when you see police cars with those four short antennas in a square pattern they are using a similar system, LoJack, for locating stolen vehicles. The patent application covers the details. Starting at figure 6, sheet 5 of 7, you can see the 4-square antenna setup towards the bottom of the diagram.

 

https://patentimages...0/US4908629.pdf

 

https://en.wikipedia.org/wiki/LoJack



#13 GuySagi

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Posted 23 September 2020 - 07:29 AM

Man, I wish you the best of luck and if someone hasn't said it recently, thank you for allowing use of your repeater (even if it's down now, or inaccessible, thanks are due for your generosity, regardless). There are none within range of my home....dang it. But I do know there are many out there you've probably never heard from who appreciate yours being on the air. My daughter's a quadriplegic who still loves to camp, and one of her favorite sites has no cell service. We haven't been back since I've gotten my gmrs license, but there's a nice tall repeater nearby, and it disturbs me to think jerks like this will compromise my (and everyone else's) ability to punch out an emergency message efficiently.  


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#14 tweiss3

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Posted 23 September 2020 - 08:25 AM

Maybe add a time out timer? 5 & 20 minutes is pretty serious. A 120s TOT would at least make it more difficult to persist.

#15 jec6613

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Posted 23 September 2020 - 08:25 AM

Man, I wish you the best of luck and if someone hasn't said it recently, thank you for allowing use of your repeater (even if it's down now, or inaccessible, thanks are due for your generosity, regardless). There are none within range of my home....dang it. But I do know there are many out there you've probably never heard from who appreciate yours being on the air. My daughter's a quadriplegic who still loves to camp, and one of her favorite sites has no cell service. We haven't been back since I've gotten my gmrs license, but there's a nice tall repeater nearby, and it disturbs me to think jerks like this will compromise my (and everyone else's) ability to punch out an emergency message efficiently.  

 

You can still usually get out in an emergency, relying on a repeater as your only way out is usually a bad idea, anyway.  Interference aside, what about power outages or maintenance, both of which are much more common?  Put yourself on another channel, and use a bit of equipment to be prepared to try simplex on the traveler channel, or have somebody listening for you.  GMRS actually has significant power available to it, 50W on UHF can do crazy things put through the correct antenna.  Most, "Jammers," are using either CCR's or something like a Motorola Talkabout.  Protip: the cheap radios that aren't Part 95 certified are generally dumping half of their power out to harmonics, and they will spill over to adjacent channels, so watch for that and open your squelch to check for it.

 

First, set up a protocol to check back with someone back at civilization ... either you check in with them a few times/day and if not they send someone, or ask them to listen for your transmissions a few times/day, like the ham wilderness protocol.

 

And if you're counting on GMRS to get out in the event of an emergency, I highly recommend getting a GMRS tuned HT antenna at bare minimum.  I have yet to come across one that comes with a decent antenna, most of them might as well be dummy loads.  Nagoya 701G/777G at minimum, and just throw the rubber duck in your bag as a, "Just in case," antenna.  If you're using a HT the same as usual with a long GMRS tuned whip on it, you can expect a bit over 6 dB of gain (that's 4x the power pointed at the horizon) over your stock HT antenna ... if you use a speaker/mic and get the HT dead vertical and away from your face, about 8-9 dB if you use your body as a giant reflector.

 

And of course, with portable Yagis and collapsible Rhombics fed from 50W, you can go crazy and sling GMRS upwards of 100 miles.

 


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#16 marcspaz

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Posted 23 September 2020 - 11:40 AM

I know this is going to sound strange, but I have had to deal with this several times in the past. Fixing it on their end, psychologically, usually works best.

First, never do or say anything on the air that would give the troublemakers an indication that they are impacting you. That is what they want... to know they are trolling you.

The next thing to do is to make them think they are having zero affect on you. On repeater systems, We have gotten 3 or 4 people together in a parking lot and all started talking to each other on the mobiles, via the repeater. Even though jammers were jamming the repeater, we can all hear each other directly and just keep talking on the radio, having a full convo. Whenever the jammer lets his/her mic up and hears everyone talking as if nothing is happening, they start to realize that they are not impacting you. Then, they give up and go away.

We do that on HF all the time too. We get some knucklehead try to cause interference on frequency, but most of the guys in the club are friends, we we get on the phone and talk over the phone in a conf call and on the radio at the same time. Me and my buddy Danny only live 35 miles apart and both have 1,500 watt stations. When someone tries to interfere with us, we just talk right over them.

Using the methods I mention... usually 2 or 3 minutes of not getting the attention they want, and get get bored and go away. Lot easier than calling the FCC, who rarely does anything.
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#17 WRAK968

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Posted 23 September 2020 - 02:12 PM

Lscott: I've seen the 4 antenna system in use for fox hunting, its an interesting bit of equipment. The doppler is a new one to me though. I'll have to look it up!

Guysagi: It is unfortunate that some will ruin things for others. I never fully understood the mentality behind it other than to just cause grief. These people would likely walk past a burning building and pretend they didn't see it. And on behalf of repeater owners, I want to say Thank You. Its when we hear others who join in on the conversation and bring friends and family online that we know we did a good job. Even the smaller systems like mine can mean a big impact for others. :)

Tweiss: All of the WRAK968 repeaters are set to a 120 second TOT just for this reason. After two minutes the transmitter shuts down and you get a steady beep tone until the system stops receiving. I monitored the repeaters input and that's why I knew how long dipstick was transmitting.

Marc: Knowing the repeater range meant it would be efficient to see if I could hunt the signal. The fact that I could hear them TX on the input side from within my house meant they were very near by. My logic was to locate them, then call their location over the air when they let up in an attempt to scare the hell out of them, instead they saw the big mean truck with several antennas slow up in-front of their place, then return and stop on the second pass. As you said its all about the mind games. Still I am considering ways to reduce jamming in the future, I'll be speaking with my father who is a co-owner and see what he thinks and come up with a plan.



#18 kidphc

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Posted 23 September 2020 - 02:33 PM

Marc: Knowing the repeater range meant it would be efficient to see if I could hunt the signal. The fact that I could hear them TX on the input side from within my house meant they were very near by. My logic was to locate them, then call their location over the air when they let up in an attempt to scare the hell out of them, instead they saw the big mean truck with several antennas slow up in-front of their place, then return and stop on the second pass. As you said its all about the mind games. Still I am considering ways to reduce jamming in the future, I'll be speaking with my father who is a co-owner and see what he thinks and come up with a plan.

 

What is funny in a couple of years these yahoos will probably asking permissions to use the repeater once they get a clue.



#19 WRAK968

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Posted 23 September 2020 - 02:36 PM

What is funny in a couple of years these yahoos will probably asking permissions to use the repeater once they get a clue.

hahaha, sad but true



#20 WRAK968

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Posted 23 September 2020 - 05:10 PM

And someone is keying the repeater again.  <_< Never understand why people feel the need to do this stuff.







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