slicerwizard
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RSSI, a directional antenna and a full tank of gas...
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- Thread starter darkness975
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Sit on the input frequency for the repeater. Use my car antenna. Use squelch and attenuation till i get closer. Triangulate may have been the wrong word to use lol I guess find a general vicinity would have been better lol
you stand a fighting chance with a directional antennae, your idea will literally just frustrate the everliving hell out of you
ecps92
Member
Body Fade works.
Hold the radio close to your body and spin in a circle - slowly
Hold the radio close to your body and spin in a circle - slowly
you stand a fighting chance with a directional antennae, your idea will literally just frustrate the everliving hell out of you
Reconrider
Inside the Galaxy
hmm so its like fox hunting?
it is fox hunting.
Reconrider
Inside the Galaxy
What are some good antennas to use for it? Something not overly huge. Also how do you use the attenuation to your favor?
mmckenna
I ♥ Ø
If you are interested in trying this, research "tape measure Yagi". Using the blade from an old tape measure for the elements, you can make a basic Yagi antenna. I've got one I made to track some UHF interference at work. The elements are flexible, so they won't break when I toss it in the back of the truck. Cost me absolutely nothing to make. Hit it with a can of spray paint so it doesn't look some goofy b@$†@®d made it out of an old tape measure.
Next time Harbor Freight is giving away or selling tape measures cheap, pick one up.
As for attenuation, as you get closer to the source, the signal can be strong enough that using the yagi alone to find it will be difficult. Adding some attenuation dulls down the signal enough that your radio will peak when pointing the Yagi at it.
Very true, however, interference from a 5w Baofeng is going to be considerably less than that same 5w Baofeng being able to key the analog repeaters and lock down the entire system. I can definitely see a move to go digital and lock things down after this, and if you're going digital, might as well throw encryption in as well.
If you want to see a great use of attenuation in pin pointing the origins of a radio signal check out this story. Probably the best story I have read here on RR. It involves finding a stolen condtruction vehicle transmitting a Lo-Jack signal.
RFI-EMI-GUY
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No stop, not the GREEN wire! BOOM!
One of the worst cases that I've ever heard of: May 2010, "Authorities arrested a 29-year-old San Jacinto [CA] woman who investigators said interrupted police and fire radio communications and made threats over the air during a two-day period,
CA Woman Arrested for Disrupting Communications | Firefighter Close Calls
Police: San Jacinto woman arrested after making threats on police radioIrene Marie Levy was taken into custody early Monday at her mobile home in the 900 block of South Grand Avenue, Lt. Mark Richards said.By Jose Arballo Jr., SWRNN Monday, May 3, 2010 Authorities arrested a 29-year-old San...www.firefighterclosecalls.com
If you do a search of her name, her life of crime did not end there.
In July of 2012 she was arrested for violating her probation by pointing a laser beam at a CalFire crew twice as they responded and then returned from a call.
In November 2012 she was arrested on suspicion of shining a laser at a San Jacinto police cruiser and a Riverside County sheriff’s helicopter. It was the third time she has been arrested on similar circumstances, police said.
In May of 2017 she was arrested for threats of violence.
In August of 2019 she was arrested for threats of violence and punishment for stalking or harassing another while having a previous conviction for 273.5.
Surprisingly the FCC database still shows her Amateur Radio Technician license as "Active" although it expired in September of 2019.
The MDC bursts would rule out CCRs. Not doubting there were CCRs involved in the incidents, just sayin' that MDC squawks would either be rogue authorized radios or slightly (not by much) more intelligent actors. Even on analog, there are ways to keep types like those from ACCESSING the system, but that takes high system discipline.
Reconrider
Inside the Galaxy
I’m amazed you sent me such a great answer and all I can gift you is a like on your post lol.
How would I setup the attenuation on my trx1 or sds100 which I would be using this on.
mmckenna
I ♥ Ø
No problem, glad you liked it. I'd been meaning to make one for a while to try it out. Finally had a good excuse.
Not sure how to set up the attenuation on your scanner, I don't own one, but I'm sure someone here can help you.
If you are going to get serious about direction finding using this set up, you may have better luck with an external attenuator. That will give you more control than the scanner will internally. I have a couple of various BNC Male to BNC Female 3dB and 6dB attenuators that I can add if needed. You can find those cheap. Or, you can find boxes that have switches that let you add attenuation as needed. Picked one up at a ham flea market about 20 years ago, but not sure what I did with it.
A tape measure antenna is great and easy to build. Our local ARES/RACES also uses a cardboard shielded tube during their training exercise. See: Santa Clara County ARES/RACES Event Detail and the slides: https://www.scc-ares-races.org/training/courses/DirectionFinding/DFBasicsJun2011v1.4_2Up.pdf
If you've got the bucks, Arrow Antenna sells loops that work well and are pretty robust: http://www.arrowantennas.com/main/fhl.html and an "up 4Mhz" attenuator: http://www.arrowantennas.com/main/4ofha.html
If you've got the bucks, Arrow Antenna sells loops that work well and are pretty robust: http://www.arrowantennas.com/main/fhl.html and an "up 4Mhz" attenuator: http://www.arrowantennas.com/main/4ofha.html
mmckenna
I ♥ Ø
Hmmm, take a listen on 465.4875. That's my repeater input at Mt. Hamilton, serves their operations up there. Someone down in the San Jose area has started using that as a telemetry channel for their systems. Master station is pretty strong, weaker reporting remotes. The signal won't open the repeater, but if they use the repeater, sometimes the telemetry will hold it open.
I've DF'd from Mt. Hamilton and seems to be coming in from the direction of Downtown San Jose, or beyond. Basically drawing a line from Mt. Hamilton through the center of downtown.
I've DF'd from Saratoga area, and seems to be coming from Los Gatos area, maybe up in the hills.
Tried DF'ing from Loma Prieta, but haven't been able to catch it yet. The seem to run on a set schedule and I have to be in the right place at the right time.
They really seem to start at 10:08am local time and run for about 20 minutes. Then it's quiet. Periodic traffic at 9:05 and 9:18am have been noted. 11:30am and 2:30pm are heavy use times, also.
I need to spend some time next week trying to catch it again.
No license for any such user in the FCC database for the area. All other know users are using analog voice with one user in Sonoma on P25, but this isn't P25 interference.
If you guys want to give it a try, I'd buy you a case of your favorite beverage, maybe see if I can swing a personal tour of Mt Hamilton/Lick Observatory when all this COVID stuff settles down.
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