Receiver Hunting

Not a myth.

Still have your radio shack and antennae in with the rest of your gear and your people?

20 responses to “Receiver Hunting

  1. Alfred E. Neuman

    Reblogged this on FOR GOD AND COUNTRY.

  2. Scanners are becoming useless with Big Brother encrypting civil comms. Any idea on how to match your transmitter’s LO spurious snot with decoys of the same frequency, thus swamping an area with noise?

    That would be a good way to find DFing snoops on the ground too. “Hey that van has circled the block three times in the last ten minutes.”

    • Grey Ghost


      The only way I know would be “modify” your comm gear to use the same IF/LO. This requires knowledge in locating the LO on the PCB, unsoldering it and soldering in a LO that matches what Leviathan uses. That may or may not be possible depending on the radio architecture and availability of parts. This is easier said than done. And that doesn’t even include moding your gear to the same IF.

      But if I had some disposable radios… I could in theory hide them in the AO and set them transmitting extreme low power cw with fake 5 number sequences that are as long as possible. Fake foxes if you will. A diversionary signal tactic that can not be avoided by Leviathan. Will they find it… sure. But if it was transmitting during your comm window, the chances are very good the fox just might draw the hounds away from their hunt of your receiver. After all there is a transmitter sending long 5 number sequences IN their area.

      I’m sure there are other ways to MIJI this problem of receiver hunting.

      Grey Ghost

  3. Here is your threat: AN/PRD-13 and AN/PRD-12. Open source information readily available.

  4. I think the IC-7300 is immune to this since it is SDR. No IF/LO on the receive side.The incoming signal is directly converted to digital and then processed. It could makes some other computer RF noise that can be picked up.

  5. You could make your radio room a Faraday cage, or just the portion in which the transceivers are located. You’ll have to buy quite a lot of copper window screen, it comes on rolls. Overlap the seams, and use several ground straps attached to deep ground rods, four or five of them.

    Placing ferrite beads on your coax feed lines is a good idea, too, since that reduces spurious radiation from your coax mesh lining.

    • If I understand the article correctly, the LO output is going out the antenna you are listening/transmitting on. It’s a tiny output, but a very sensitive radio might be able to hear it, between your transmissions, even if you never transmit. Shielding your room won’t help with this. This is why TEMPEST is so frustrating, and useful.

      • I’ve used Tempest detectors and seen, but not used, Tempest resistant keyboards. Yes, folks, your computer keyboard radiates electromagnetic (radio) emissions unless it’s shielded and grounded.

        Ferrite beads, which aren’t particularly tiny like decorative beads, form a electromagnetic choke, preventing spurious emissions from traveling along your coax feed line.

        Here’s one source.

        You want them large enough for the coax to pass through, though the split versions can work, their longevity outdoors is not good. For two meters I ran about six beads just below the coax connector near the antenna. I put them inside heat shrink tubing, yes large heat shrink, and used black silicon adhesive to keep them in place. The beads also force all of your signal to the antenna, without them some power travels back down the outer coax conductor.

  6. The other white meat

    Since unofficial groups can never compete with official groups in the hardware realm, other measures have to be borrowed from the past. Assume that the official team has excellent networked AI 4-D RDF (linked to circling drones and robot artillery) and has characterized your hardware and operating modes through hard work (torture & murder, along with credit card records). What does the unofficial team do? Cardboard cutout targets everywhere, in what look like random-but-reasonable places-and-times, among real things that look (on the RF spectrum) a lot like the cardboard cutout targets that are assets belonging to the official team. The unofficial team may/will bring some damage on the locals (90% who are going along to get along with whoever controls the food shipments), but the marking on the fragments of cases came from the official side. Or, nothing happens for a while, which is great, compared to the UT being instantly and automatically slaughtered remotely (perhaps, forcing actual men to do missions like the “OBL extraction” at tremendous cost). Time going by is to be considered a WIN! by the Unofficial Team everywhere because the Official Team is bankrupting itself.

    The AI will report success of the mission in all cases.

  7. Y’all can also acquire one of these to maintain vigilance on your commo shack and to detect emissions where none are supposed to be, such as people sneaking recording devices into meetings.

  8. DuckDuckGo: “Operation Rafter”
    (these 2 links have similar but different content–read both)

    And more on the technique:

    Supposedly this is how the UK gov tracks down those using television sets without paying their television TAX.:

    I’ve also heard that this method has been used to estimate radio station market share by putting a receiver at a commuter choke point to pick up what stations they’re tuned to, but I don’t have a reference for it.

    From here:
    “Local oscillator radiation
    “It is difficult to keep stray radiation from the local oscillator below the level that a nearby receiver can detect. The receiver’s local oscillator can act like a low-power CW transmitter. Consequently, there can be mutual interference in the operation of two or more superheterodyne receivers in close proximity. In espionage, local oscillator radiation gives a means to detect a covert receiver and its operating frequency. In the United Kingdom, local oscillator detection is used to find television receivers being used without a television license.[citation needed] A method of significantly reducing the local oscillator radiation from the receiver’s antenna is to use an RF amplifier between the receiver’s antenna and its mixer stage.”
    “Local oscillator sideband noise
    “Local oscillators typically generate a single frequency signal that has negligible amplitude modulation but some random phase modulation. Either of these impurities spreads some of the signal’s energy into sideband frequencies. That causes a corresponding widening of the receiver’s frequency response, which would defeat the aim to make a very narrow bandwidth receiver such as to receive low-rate digital signals. Care needs to be taken to minimize oscillator phase noise, usually by ensuring that the oscillator never enters a non-linear mode.”

  9. Grey Ghost

    1. It’s clear that Leviathan tries to get all their radios using the same IF/LO “signature” so they can tell friend from foe with some reasonable amount of certainty. Somehow I doubt commercial radios have the same LO signature. So get slightly older .mil radios or radios that use this same IF/LO signature. Then in effect you are “hiding in a patch of grass in their backyard”. This is not foolproof but it helps to hide in plain sight and may cause some confusion on the part of the Leviathan operator whether human or AI.

    2. It’s not exactly clear to me how the LO harmonic signal is “escaping”, either via the antenna or “through the case”. It could very well be through BOTH methods. Maybe Sparks31 would like to clear that up. At any rate, I think Pat Hines is on the right track. Faraday cage the radio(s) and/or the radio room if the LO harmonic is coming through the case. This has other benefits as well. While ferrite beads work ok for common mode current problems on antenna feedlines, I think large 2.4″ or 4″ mix 31 toriods with as many wraps as you can get of the antenna feedline may be a better way to knock down the LO harmonic if it is escaping via the antenna. What do you say Sparks31?

    3. Computers. IIRC it was the video subsystem that was the main culprit back in the day when CRTs were first used as monitors and the only networked computers were in DARPA. I’m not sure how LCD/LED monitors stack up against the old CRT systems for vulnerability, but my guess is LCD/LED video subsystems are probably worse, though I have no evidence to back that up. Hacking into computers via network interfaces whether wired or wireless (incl bluetooth) has been around for as long as computers have been networked. There is even “side channel” attacks. Think ubiquitous “wake on Lan” technology that is built into ALL network interfaces.

    Why do you think Leviathan came up with SCIFs and classified network architectures?

    One of these days I’d like to talk to Sparks31 about “vertical hacking” of classified network architectures! Something I picked up from monitoring Bugtraq about 15 years ago.

    Grey Ghost

    • Keyboards radiate so much RF that a non-Tempest protected keyboard can be copied and the keystrokes broken out so that you can follow what the man typing is typing. Yes, it’s that bad.

      The old CRT displays certainly radiated, but, as far as I know, not so you could see what was being displayed. Way back, when the Soviet Union used microwave signals to relay their long range radar images to a central location, certain US agencies could break that out, put it through to a standard, US built radar scope. That is, the US agency could see what the Soviet operator was seeing. The Soviet Union had severe issues which restricted their use of land line communications over long distances.