To “sort out” a hard to get radio signal from either a jamming station or simply an interfering station on the same frequency, maybe you could try the “Anti-Jamming Antenna” presented by Keith Perron, at PCJ Media, producer of THE HAPPY STATION>
http://pcjmedia.com/anti-jammng-antenna
Reflector
It’s basically a reflector to null out signals from one direction, or several if you build more than one and place them around the actual receiving antenna.
Follows the same principles as yagi’s.
They do work pretty good…only problem is this is highly dependent upon the propagation of the signal wanting to be received and its point of origin versus the propagation and point of origin of the jamming signal and strengths of each.
The technique can work…or null out the signal you are trying to pick up…a 50/50 thing, but when the factors are all in a nice neat row, it works well..and is a very old technique I might add!
RFB
for am an nrsc loop, for fm a
for am an nrsc loop, for fm a sector type antenna. both null out signals from the undesired direction.
Old AM Loop
I had a vintage Pioneer monster stereo receiver..damn thing weighed 70 pounds easy. Massive power transformer that took up most of the internal room and comprised of 80 percent of the unit’s weight. Anyway it had the on-board rod antenna attached to the back, but it also came with this loop antenna that attached to a fitting near the rod antenna. When mounted and hooked up, you could turn it and help eliminate noise and background junk on weak stations.
Worked really well. Ended up selling it in a moving sale all those many moons ago.
Remember the old analog tv receiver rabbit ear antennas with the UHF loop in the center? Sometimes moving the UHF loop would help with the VHF reception. Then again helping reception with the rabbit ear antennas could be done with a simple wad of aluminum foil or added coat hanger!
RFB
New Idea?
PURPOSE
I was just brainstorming again only this time over this anti-jamming antenna. Judging from the fact that most jamming is not CW (continuous wave) anymore and has mainly an audio component to it’s MJ (modulated jamming), I thought a novel non-RF based ECM (electronic counter measures) approach could be deployed.
BACKGROUND
MJ makes it very difficult to actually hear anything from the intended victim station being jammed. Therefore if you could attack the audio source verses the RF source, like what the anti-jamming antenna attempts to do by peaking & nulling, you might be able to hear the jammed station. Of course this only applies to AM* (amplitude modulation) not FM* (frequency modulation) signals (i.e. FM capture effect?).
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*Note: AM/FM – not talking about just AM or FM Broadcast band here. Referring to the RF modulation technique.
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PROPOSAL
The approach I am talking about is *audio-phasing*. If you had TWO portable receivers tuned to the same AM station, one of them would have a simple directional antenna to enhance (or peak) the *single* OFFENDING station so you get a pure bad-guy jammer audio signal with no hints of the good-guy signal at all in the background audio. You might even use a RF attenuation circuit to reduce the RF signal to eliminate the *wanted* good-guy signal totally. The other receiver would hear both good & bad guys equally as well*.
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*NOTE: Therefore, if we remove the offending MJ, the bad-guy strong but mostly silent RF carrier-wave component really doesn’t count *IF* you can hear the good-guy audio even just a little bit in the original signal background.
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REMOVING THE MJ
Now you need to feed both audio outputs to a novel audio-phasing processing device. It essentially would be a two-channel audio amplifier. You could convert both analog audios to digital (i.e. DAC), reverse the phasing 180 degrees out-of-phase on the bad-guy digital signal, mix the two bad and good digital signals together, then convert the mixed signal back to analog (i.e. ADC) to an audio loudspeaker. The bad-guy digital audio signals cancel themselves out almost totally. Doing it with digital makes signal phasing processing more pronounced than just doing it all analog, if analog is even possible.
CAVEATS
If you can maintain a *good-guy-free* signal on the original bad-guy-receiver then you might have a jammer-free signal on the final output. This would apply to MJ’s like white noise, white noise with modulation, simple tone, bagpipes, stepped tones, swept tones, FSK spoof, crypto spoof sounds, etc.
SUMMARY
I don’t know if it will work but someone could experiment with this and maybe patent it for themselves? If it is really novel and not done already consider it a gift (LOL).
Spooky
P.S. – Remember this WON’T work if you can’t hear even a little bit of the wanted signal. If it’s buried totally 100% by the jamming signal then this won’t work. It won’t make something that’s just not there (i.e. detectable) magically appear.
Comprendo
I like your idea and understand it….. it is worth testing.
With the ability of variable digital audio delay one could fine tune the “phase angle” of a particular audio signal (the jamming noise), which is another way of saying “shift in time-relation”, mix back with the original jamming noise, and cancel it down to the background.
By ALSO using the antenna method of canceling an RF interference, perhaps BOTH methods could result in a very clean reception of the wanted signal.
Comprendo indeed!
Yes Carl you are right on the money! Your idea to include BOTH systems would be a win-win situation. Maybe some manufacturer like Yaesu, ICOM, CC Radio, WinRadio, etc. Should look into it. The method proposed in the OP can be attributed to the Chinese and does not seem to be patented yet.
My proposal does date back to digital phone patches and voice scrambler technology. So that part has been done already. Just not like this (I think). So its off to the Patent Gazette and your $1,000 USD fee for preliminary request (LOL) I won’t as I am too broke… ;-(
On another technical note: white noise is a notorious counter measure to any audio trying to be listened to. Like running the bathroom water in your hotel room to avoid listening devices. However, even though it’s wide-band high frequency noise it can not withstand a mirror-waveform-audio-cancellation method. Even pseudo-random noise (i.e. broadcast-radio talking head feed) is vulnerable when you have an exact source feed to use.
However, white noise and pseudo-random noise are highly effective to old technology jamming and electronic surveillance – IMO that is.
Spooky
Subject Bending
While we’re on this topic, let me switch to a different topic. Except, that it is somewhat related.
We have all had the experience of using a video camera aimed at a talker. The view of the talker can be improved by just zooming in for a close-up on the face, but the on-board microphone in the typical video camera picks up an omni-directional room sound, with the voice always sounding far away in the annoying reflections. Thousands of videotapes on a hundred shelves suffer from this imperfection. It is usually the sound that is more important than the picture, so we need an invention that can pick the voice out of the room echo and tune-out the bad reflections, so it ends up sounding like a good close-up voice recording.
Start working today, and bring me your results by Tuesday next week.
I’m a invention junkie!
Carl,
Asking me to find a technical solution to a problem is like offering junk to a junkie. I live for this stuff. Now you have got me started. I hope I can offer some insight into your technical problem.
The Problem
Poor audio recording techniques.
Simple Solution
1) Make sure the microphone is always close to the mouth of the human speaker.
2) Use a small wired boom noise cancelling mic over the ear. They do this in Opera and Playhouse theaters. All cameras have an external audio/mic input. Putting foam and rubber band around the mic will stop wind pop from the mouth or from outside air. Try mounting the mic up on the cheek away from the nose and mouth and you won’t need the wind pop foam.
3) In the Hollywood movie business they hang a wired boom mic on a long stick right over the human speaker’s head. A boom-man (sound engineer) must hold it over whoever is speaking but keep it out of camera’s line of sight. The mic must hang on rubber bands to hold down stick movement noise.
4) You can build a shotgun microphone and aim it at the human speaker from across the room. Here’s how to build one from metal or PVC pipes: tinyurl(dot)com/3ofwvh3 – replace (dot) with a period.
5) Keep your studio in a small box like room (i.e. walk-in closet?). Stay away from large echo-ey rooms.
6) Pad the room walls with sound absorbing foam tiles. It looks cool too. You can get it from any music store. Or just make some yourself. Get some newspapers, crumble it up, and stick it behind some large pieces of cheap Home Depot perfboard. The perfboard has holes which help the sound not reflect as sound goes into the newspaper. Its easy to prop up temporarily or you can nail it up. It don’t look as good as pyramid tiles but you could always paint it. (It acts like an excellent temperature insulator too – warm in the winter and really hot in the summer).
7) I heard somewhere that news programs use two unidirectional mics next to each other aimed at the human speaker. I think somehow it not only enhances the gain but also cancels out side echoes.
8) There are noise cancelling microphones on the market that have separate auxiliary mics to capture the adjacent noise and then cancel it out allowing only the human speaker to be heard. They don’t seem to be cheap though.
Not so Simple Solution
OK if you have a lot of bad audio on video tapes your going to have to redub all of them. First you need to get a good audio editing program like CoolEdit, TMPGenc, Ulead VideoStudio, or get what the government uses – SOUNDFORGE PRO. I just picked up Music Center by Data Becker ($29.99 retail) for $2.99 catch-as-catch-can at SAVERS (they are worldwide thrift store).
This process will be long and laborious. You will have to bring in the bad audio, reshape it, filter it, etc. then copy the whole thing unto the audio track of a blank VHS cassette. Then you’ll have to copy over the video with no sound. Hopefully timing lip-synch will be good – it’ll be tricky. Your best bet is to just forget about the old tapes and just practice “safe sound” (as above) for the future.
Spooky
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Different Subject
World’s Cheapest Part-15 Broadcaster Console 1610 khz (yes its a kid’s toy) – Wild Planet DJ Console. You can get one on EBAY or Amazon for about $20. Toys-R-Us may still sell them. Here’s a demo video: youtube(dot)com/watch?v=7WIocldgoU4 If you could modify it you could take the audio and feed it into a better Part-15 transmitter. Put a wind pop foam filter on the mic.