3 ms·
That's what I meant when I said "wardrive" around the neighborhood and look for where the signal strength peaks. It's easy in theory, but I'd guess you'd proba
by throw20102010 7y ago
That's what I meant when I said "wardrive" around the neighborhood and look for where the signal strength peaks. It's easy in theory, but I'd guess you'd probably only narrow it down to plus/minus two houses in every direction- UHF attenuates through walls, but in air it is more gradual, and so you wouldn't get a sharp peak as you walk around. So now you have eight houses to go check. But once you started knocking, probably all the neighbors would either say, "yeah, that's probably Bill, he's does electronic stuff" or maybe they would say, "that's might be my neighbor I've never met."
A strong directional antenna would help, but that means that you have to build it yourself, I'm not aware of an off the shelf antenna that has high gain at 315 MHz. So
- crankylinuxuser 7y agoThere's a new piece of inexpensive gear for RDF: KerberosSDR. It's a quad input coherent radio receiver based after the RTL-SDR chips. One such function is it can give direction and strength of signals in a wide area. And I find this electronic kit antenna works well as long as you pull it out for the appropriate frequency: https://www.nooelec.com/store/ratlsnake-m5.html https://www.nooelec.com/store/ratlsnake-m5.html I use 4 of these for my KerberosSDR.
- throw20102010 7y agoI saw that these are shipping and have almost convinced myself to buy one. I think they're pretty neat and now a wideband phased-array direction finder is a project that a smart high-schooler can do, at a price point that many people can reach. Maybe the next time this type of interference occurs the headline will read different: "Local kid solves problem with science fair project, stumped adults for weeks." With that said, these KerberosSDRs (or any multi-channel coherent SDR solution) are not widespread, are considerably more expensive (6-7x more than a single RTL-SDR), and are only recently available. So my previous point still stands about how armchair hackers can talk about how easy this problem is to solve in theory but they lack the actual equipment to do it.
- crankylinuxuser 7y agoOh absolutely. A simple RTL-SDR is widespread, but anything coherent is absolutely not. I mean, the Ettus 4x4 pcie card is coherent, but it's also starting at $5000 for the card. And since it's a pcie, it goes in a very non-portable computer. The KerberosSDR has one very significant disadvantage: the databus is usb2. The theoretical max is 30M samples at 8bit I and Q... And frankly we need much more bandwidth. But for a beginner foray into coherent radio applications, a KerberosSDR for $100~ is crazy worth it. Now, the older way of doing RDF (I'm a Ham, btw), was to get a handheld receiver capable of listening to the freq in question, highly directional antenna, take measurements and move. Effectively, the human with a receiver is the manual triangulator which can be trained with experience. That was because gear that did triangulation was $$$$$$.
- tknkx 7y agoIn the context of this article, having eight houses to check is soooo much better than having absolutely no clue. If it's not a malicious actor, you'll find out what's emitting the signal in a matter of an hour tops. Being able to do that using a $10 device from ebay is fantastic.
- megaremote 7y agoOk, you have 8 houses to check. What do you do now?
- tknkx 7y agoYou knock, explain the problem, ask if they've installed new electronics lately, especially remote controlled/domotics stuff. Repeat until you get a satisfactory answer. Chances that you will get one are very high.