KrakenSDR Low Power FM Transmitter Hunt
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- čas přidán 3. 07. 2023
- Find more information about KrakenSDR at: www.crowdsupply.com/krakenrf/... and www.krakenrf.com
In this video we are using a KrakenSDR to hunt for the location of a low power FM transmitter (LPFM) station at 106.7 MHz. These low power FM transmitters are legal as unlicensed transmitters as long as they operate under certain restrictions, the main one being that they transmit at under 1 watt EIRP. LPFM stations are typically operated by local communities or niche radio stations.
Because they are unlicensed, there is no official record and their location doesn't show up in the radio spectrum management database. A requirement of LPFM is that the station broadcast the contact information of the owners regularly, but it can be difficult to locate non-compliant stations that don't do this. But the KrakenSDR makes finding them easy.
The array is 45cm in radius, which is about the maximum that my RAV4 car roof can fit. Some of the antennas sit on a slight curve on the roof, but this appears to have negligible effect. The spacing factor is about 0.19 (optimal is 0.5 - a much larger radius), but even 0.19 is sufficient to find the transmitter fairly easily.
Even with the small spacing factor, KrakenSDR ends up pinpointing the transmitter to within a couple of meters. - Věda a technologie
I really really love this project. I've been manually hunting a few times with a friend.
We have found some "dumb" analog relays from the local authorities and once we even tracked down a foxhunt :)
I really appreciate this awesome device and love the idea of implementing a navigiation into the app to help with convienince.
I hope to get my hands on a KrakenSDR next year. Manual DOA is fun, but that device is so satisfying :D
There are so many signals I am wondering about, and I would love to create a map of all misc transmitions in my hometown :)
Thanks for the video! I am really wondering how few people are interested into those kind of videos.
Maybe typical ham radio operator are "too old" for the hightech stuff and stick with old analog tracking technics, and the younger people, that are into SDR might not enjoy something like tracking down transmitter and antennas :D I love it tho, really curies for stuff like this.
Cool tech thanks for the demo
Nice one! -cool music
Great! More examples, please. Is the 5-antenna product getting close to shipping?
The five-antenna product, known as KrakenSDR, has been shipping for over a year.
Very cool, im interested
I was thinking about running a linear array for better resolution, and starting out with a handheld yagi, or loop antenna null, to get initial bearing. Plus, I dont have a permanent rack/mount that I can just throw onto roof with antennas hard-mounted and I dont have a template for circular. Making a linear array with a tape measure and eyeball would be easier. First, have to wait for decent buck converter to arrive next week. My chinese cigarette lighter adapter didn't provide enough amperage and the wifi kept dropping out.
That is a LOT of driving to find it. How does this approach compare going to a few, elevated positions and doing a DOA measurement from a static position to get an initial fix ?. If free from a lot of multipath signals, that should get you fairly close to the target ? Then repeating with a few measurements bracketing the target ?
About 50 minutes of driving for this one (I edited out a quick lunch stop), with ~10 mins driving around the location to search houses for the antenna. The drive time of course depends on how far away the transmitter is. This TX ended up being 20km away from the starting location which according to Google maps is anywhere from a 26-55 minute drive at that time of the day depending on traffic, so the only real extra drive time was spent on the antenna search. If it was only a few kilometers away the drive time could be 5-10 minutes.
You can also do manual triangulation from a hilltop with KrakenSDR, but actually that method takes significantly longer (drive to each elevated position, set up equipment, break down equipment, drive to next elevated position, triangulate, drive to TX, search for TX...), and of course doesn't work if there aren't any multipath free elevated positions within the reception range of the TX. Then if you chose bad positions and the TX is actually much further away than you thought so you don't get a good intersection, then you need to find new spots etc. It's easier to just drive closer and closer while automatically triangulating through the app, and end up directly at the TX for inspection.
Kraken actually loves multipathing more than direct LOS. Watch the lobes on the top part of the screen. If you can get some height with it though it nails location pretty quickly.
@@OllieVK You will definitely get more multipath corruption on the ground than when up on a hill with good LOS. But the beauty is that it doesn't really matter, because you can take so many readings while on the move that any multipath averages out.
Also wanted to note that a lot of what might look like multipath corruption in the video is because I did not turn "pause data collection while stationary" on for this run. So when the car stops the GPS on the Android device doesn't get a quality heading, and the lobe bearing is hence wrong for the period of time when the car is stopped. Also with a small spacing factor for this frequency, multipath corruption becomes larger. If a larger array could fit on the car it would improve results. Regardless, the TX antenna was located to within a couple of meters, it would have just been a few minutes faster with a larger array.
Thank you very much for your video. My question is that can I use kraken sdr on 2.4GHz and 5.8GHz band without moving?
The frequency range of the KrakenSDR is 24 MHz -1766 MHz.
@@thekraken2086 Lets hope Krakan2 has 0-6Ghz -maybe based on the HackRF AD chipset or better
I need to figure out how to modify cells of the Radius Array Calculator, so that I can have a list of maybe 20 frequencies on 2m, and the corresponding Interelemental dimension, based on a static array size. In other words, if the dimension is 22.2", what multiplier is used for frequency of 146.520. What about 146.55, or 147.015, etc. Would be nice to have a quick way and make a small printable sheet. I'm sure it's possible, but I'm not a "freak in the sheets", as IT would say.
Will the radius affect the accuracy? Wondering why choosing spacing factor as 0.19
Yes, a larger spacing factor will provide better resolution.
Adding that the reason for the small spacing factor is simply due to that being the largest size possible to fit on this vehicles roof.
Don't be a little snitch.
That's what I was going to say.