RF Amplification Problem

Hmmm, you are saying there is an RF amplifier IN your home?
I'd think it very unlikely...where would it be getting it's power from?
Turn off the mains power and see if the signals are still there.
I am a firm believer in 'cockup' rather than 'conspiracy' generally and am also rather wary of (don't take this wrongly) paranoia.
I don't think you could conceal and power such an amplifier too easilly...and why6 on earth would you?
More likely you are in line with a transmitter somewhere or have something which is a tuned length picking up the signal.
The farmers in Rugby used to be able to hear the radio on the their pitchforks in the early days of radio!

Good luck.
Del

Del,

I've collected data series involving switching the power mains off. The distinctive signals are still there. I've also collected data during a localized power outage: signals were still there. However, I can't say for certain that all signals are present at the same amplitude. What I have noticed is that amplitude is reduced after a couple of hours with the power out. There's also some correlation between an increase in the electric bills and the onset of RFI troubles here.

RE: paranoia: see above comment about the Radmin program installed on my computer by intruders. It is physical fact: there was access to my home. So it is only fair to consider the possibility that there is gear in the house. If there's another explanation, I'm good with that: I have nothing invested in one explanation or another: I just want the facts.

If the better explanation is that I'm in line with a transmitter, and if others agree that there's nothing covert capable of this level of amplification, it could save me the nasty business of crawling around in the attic. Thanks!

I have been told by a friend that Radmin can be installed remotely on a PC that is not properly protected against viruses, does not have a software Firewall, does not have a hardware Firewall, and/or by going to bad websites, and/or opening emails with hidden Trojans, or a mix of all....or an infected CD or floppy could also do it!!

With regard to the RF, it sounds like radio stations to me, possibly combined with military communications.......are you in a house that is fairly high up somewhere, where reception would be particularly good....or low down and right next to a military establishment.

Have you gone outside, in your neighbourhood and checked the signal strengths for your neigbours? Is it the same?

What tells you that these levels are dangerous?

If you want to stop them, you need to build a Faraday's cage in the rooms where you live, not a small job, but simple chicken wire (correctly earthed) will do it......

Thanks Andy. This is a residential area and there's no major industry or military near by. I have the impression that the military use high gigahertz for various things, but this is out of range of the measuring instruments used. The frequencies in question are unlikely to be military use, IMO. There is a military air station next to the airport, that's about 20-25 minutes drive from here.

Re: Faraday: well... I'd rather not be the one that has to live in a cage.

Radmin21 is part of a program that gets transfered through E-mail, file sharing, or embedded inside other programs. It is spyware that allows the user to see what is on your monitor. It is to steal passwords or personal information. If you transfered files from another computer that were infected, it will also transfer the spyware. If the system is never put online, you have nothing to worry about. But wherever you transfered the file from will definitely require attention to have it removed.

Thanks for the spyware alert - this is what I expected it to be, but the people I consulted (the ones who installed Windows for me) said it would "most likely" be used the other way. They never mentioned you could accidentally pick it up with email.

I found the "new" Radmin folder in "My Documents" the first time I booted it up after I found physical evidence someone had been in my home office: they left a slip of paper with my phone# on it, lying on the office floor. Phone records showed calls from unknown callers placed while I was out. I assumed the program was installed in that incident. I hadn't recently been online. It definitely wasn't in "My Documents" when I used the computer before the illegal entry. But it sure did come off the internet: we traced the serial number and , of course, it was a free download: no traceable.

Thanks for the good advice, I don't use this box any more nor Windows either. At the time, I got my brother to help uninstall the sucker, so it was purged the same day.

It can go online all by itself if you are always connected to the net or LAN.....change all your passwords immediately.....!!

artsmith,

I've had a little experience with this type of tech, although I wonder why you would be the subject of their interest. There is a device called a "micro ear". This is a device used to monitor communications within your home through the phone lines. It is the size of a normal briefcase and needs only to be within 1000 feet of the subject location. We They only need to dial your phone number and you have no privacy. They can listen to any individual line in your home or all at once. You hear nothing if you pick up the line, just the normal dial tone. This is done through frequency modulation. Yes, it also works with cordless and cell phones.

As for the computer, have you ever called a help desk and given them access to use your computer remotely? Well they only ask for permission because they know you are looking. They can access your computer at any time. Big companies and government have done this for years. If you are using a computer at or for work, they can remotely watch every thing you do. They can even make changes as you work. There are keystroke programs that send a copy of all of your daily computer uses,and alert someone each time you log onto any computer anywhere, as long as you use a known identity.

I had better stop here, they're outside. Good luck, and remember whenever you log onto a computer you should always covvvvvvvvv

"micro ear"

ah, is that the one where if you pick up the phone and listen, there's no dial tone? Oops, time to change the music again. Sometimes, if you depress a button halfway, again so there's no dial tone, you can hear communications on the line. All pretty standard fare for telephones though... in my experience this can happen at any time for mysterious reasons fondly referred to as "lines are crossed" or somesuch.

How useless would that be, somebody monitoring ..what I say when there's no one else in the house?... Aaaaagh.... For a far more exciting, really scary criminal scene they should try listening for clean communications network signal in ? 149/159 MHZ maybe, if the survey was any good. Probably need a warrant for that.

There's some wild hairy video retrace though, (15735ish) and a booming video sync pulse that are typical of signals environment in the house, but not out around the area. Commercial TV retrace was hard to find, but where I got it, it was very clean, narrowband, composite video with no separate sync pulse. 181 Mhz is a commercial TV license here, and is amped up pretty high in the house, so this could explain a strong retrace. But doesn't explain the broad, dirty quality of the signal nor the separate 60 hz "sync pulse". I must admit, it doesn't foster feelings of enjoying any privacy...

The thing I'm really bothered with here is the incoming RF and RFI. 40 Mhz and 159 Mhz stuff. Unsolicited, not-broadcast-radio-or-tv, interference of various kinds.

KEYSTROKES: I swear I have seen this sh@# on my computer: spellos and grammos: I even had a date changed once that screwed up what I had to say. Does this stuff really exist for linux? after all: I've seen this on Open Office unless I am mistaken. Is there something to do about it on linux?

I can't address the computer issue, but here are some thoughts on the rf issue.

We need to get some terminology straight first. You said there is amplification of 20 dBm. Amplification is in dB; it is a ratio. If you maybe meant you were getting 20 dBm (100 mW) signal level from antennas in your home at the frequencies you cited, you either live very near the broadcast stations, or someone is indeed amplifying these signals.

But I am going to assume, for this post, that what you meant is that signal levels at the frequencies cited are 20 dB higher in your home than without.

At the levels that typical broadcasts are received, several kilometers or tens of kilometers from the broadcast antennas, if you wanted to boost these signals with an amp, a 1 Watt amp would be more than sufficient, and that is a very small device that plugs into ordinary mains power. But you have to be careful how you do that, else you get a positive feedback effect with the rf input picking up the amplified output - that's one of the reasons why they do translator stations, and don't simply amplify the original broadcast signal at the same frequency.

So I don't think there is intentional amplification going on.

Another possibility is that significant metal in a structure will act as an antenna and in the immediate vicinity of that structure the rf currents flowing on it will make for a stronger localized field than if the structure wasn't there. You can experience this if you are driving at the fringes of an FM station broadcast area and drive under a bridge; momentarily you will get much better reception, which will immediately fade as you leave the bridge structure behind.

With the info at hand, I'm guessing this latter is the more likely scenario.

Thanks for answering.

Terminology: The measurements are made in dBm that is field strength. When I used the term "amplified" I meant that the signals in question are 19 or 20 dBm stronger than elsewhere, only on the inside of my house. Nominal confidence interval for the instrument was +/- 3 dBm.

For example, the 102 Mhz signal (commercial FM) measured in the range of - 62 dBm to - 52 dBm (those are minus signs!) in other locations: -34 inside my house and -35 outside on that day. that is 18 to 28 dBm difference.

The 40 Mhz signal was -50 dBm to -51 dBm at all outdoor locations including right outside my house. On the inside it is -31 dBm or 19-20 dBm stronger.

159 Mhz was -66 to -62 dBm everywhere measured, except right outside the house -54 and inside the house -45 dBm. That's 17-21 dBm stronger inside the house than the "norm" around the area within 15 to 20 minutes drive.

My understanding is that dBm is a log scale but I am very hopeless in certain maths department and can't get past the simple equivalencies: I've read that 20 dBm is the same as one hundred times stronger signal.

I guess I shouldn't use the term "amplified" in this context: I am assuming that it is amplified by something in or near the house and that's what I wanted to find out. What would gear look like that would amplify signals in these bands by 100 X ?

The signals have been amplified by 20 dB. That is the ratio of -60 dBm outside, and -40 dBm inside:

-60 dBm + 20 dB = - 40 dBm.

You can't do this:

-40 dBm + 20 dBm = -40 dBm^2

Anyway, I suspect you have a passive device in your home, either a metal beam, or more likely just the house wiring, picking up these external signals and re-radiating at a higher level within the home.

This would be easy to check with an rf current probe that can be clamped around household wiring, like in the attic.

I have a lot of these; can loan you one if your field strength meter has a coax input. You pay shipping, both ways.

BTW, dBm is a unit of power, not field strength. The field strength can be related to the power reading given by the meter by knowing the gain or antenna factor of your antenna. But there is no need for this job; you are just looking at relative values.

Many thanks to you for helping with the terminology: it's obvious when you write out the equation. I am obviously clumsy with stuff I have tried to learn by reading, thanks for your patience.

RE: passive device: I have done some reading about antennas and understand that the "tuning" effect is related to antenna length vis a vis specific frequencies. So there should be some reason why 40 Mhz, 102 Mhz and 159 Mhz are resonating but others are not. Should I be looking at specific lengths or spans in the wiring that might correspond to these frequencies. Don't forget, in the 102 MHz example, there are a bunch of stations very near in the band (at least three around 97, 98, 99 for example), and they are not even picked up at all with the broadband setup used. Why the specificity? It would have to be pretty much the right length, do you think?

Lets say I have an attic full of wiring. The rafters run about 28 feet. I can measure the spans of wire that run along the rafters or any branching off at 90 degrees to that. If the wiring runs 25 feet (as opposed to the full 28) that could explain 40 Mhz reception. Five foot lengths would be optimal for 102 Mhz. and for 159 Mhz, lambda over two would be 3.125 feet for optimal antenna. Is this a reasonable approach?

I have an RF probe in the range 1 Mhz to 1 Ghz, it is not the clamp type but has a little copper hook on the end. And I have a DMM to plug it into: the fancy field strength meter is long gone, I only had it for a week. I did take the probe and DMM up in the attic at one point: the readings up there were very high compared with the main floor of the house, and maxed out the meter when held to the roof in certain places. The wiring is in the rafters below: there wasn't anything that I could see on the inside of the roof to account for antenna activity. But there are some odd, unaccounted for patches on the outside that look like a glue of some kind. It's a very inaccessible spot to get to unless you dangle from the peak. Is there anything RF related that would look like this? (Hopefully not! The attic is bad enough.. )

The DMM is a broadband device in its operating range (up to around a few kHz, somewhere below its sample rate). Above that it's a crap shoot, and you cannot rely on it. Most likely your DMM was responding to 60 Hz fields, not rf.

You are correct that if the passive "amplifier" is structural or electrical metal, it should work the same for any signals with similar frequencies: it's not as if you are going to have such super high "Q" that 102 MHz is amplified, while 97 MHz isn't. The only way that could happen is if one particular wire were so oriented that it was parallel to the electric field component of the 102 MHz wave, and perpendicular to the incoming 97 MHz electric field while being parallel to its Poynting vector. The chances of all that happening, with the rat's nest of wiring in a typical attic, are vanishingly small.

I don't know what those patches are on your roof, but what they are not is efficient antennas in the FM BCB. As you noted, the dimensions of useful antennas in that band are on the order of a meter.

I'm not sure what your 1 - 1000 MHz probe looks like, but any probe working over that broad a range is either poorly matched at the low end, or designed to drive a very high impedance load. Now your DMM is high impedance, but it isn't designed to receive rf. That's another reason you are likely sensing 60 Hz fields, not rf. An electrically short probe is only an efficient pickup device when it is open-circuited; it cannot deliver power to a circuit.

emc_c , if I have got my head around this, for the 20 dB amplification

a 1 Watt amp would be more than sufficient, and that is a very small device that plugs into ordinary mains power. But you have to be careful how you do that, else you get a positive feedback effect with the rf input picking up the amplified output -

Could these "positive feedback effects" produce the sort of power surges that have been frying my monitors, hard drives, and so on ?

Is there some way an electrician could find such "positive feedback" sources other than visually examining all the wiring?

No, a 1 Watt amp can only put out 1 Watt, or slightly above that. It's like if you have positive feedback on an audio amp, you just hear a squeal, but the amp can only drive what it is designed to. No more.

A 1 Watt amp, driving a matched antenna, could put out enough to possibly cause interference to your PC equipment, if the antenna were in its immediate vicinity, but it would fry nothing; if by "fry" we agree that means breaking things so they no longer work, whereas by interference we mean that the PC equipment works properly when the rf field is removed.

Thanks for your replies. I'll think on them til I get it straight.

Are you a government official, a drug dealer or a terrorist? Are you in an ugly custody battle with a psychotic x-wife? If the answer to all these is no, then you must ask yourself, why would someone go to all this trouble and expense and possibly risk incarceration to find out what I'm up to?

Your high energy bursts at 1-3 GHz are probably from your spread spectrum cordless phone. The periodically transmit, I suppose to stay synced. I had that problem in my shop a few years back. All the other frequencies I could account for by local TV and radio stations and I had been doing work for the spooks so I became quite suspicious until I found the source.

Do you have any analog TV's or older receivers operating? Some of the older ones were not very well shielded and the local oscillator put out quite a strong signal at whatever frequency the unit was tuned +/- the IF frequency (10.7 MHz for FM or 455 khz for AM).

rcapper: no no no and not even. Rest assured this is not the government: private cops, maybe more likely. The motive is profit, don't ask me to explain because that's not what this thread is about.

On the burst signal: I dug up some images for you to look at. It's not a cordless phone, I don't have one. Also it's not only at home. Local radar experts don't recognize it, suggest telemetry.

I'd like to know, what can you say about a signal's purpose from looking at its form? I'd also appreciate any help with the right terms to describe it.

Here's an image showing the pulse repetition rate: PRR: 4.82 seconds I believe. The PRR is consistent and a reliable way to recognize this signal, afaict.

Here's a burst in closeup. The burst width is about .045 seconds. I count 7 groups of four 'spikes' of varying length: the length of em varies from one burst to the next. Don't know what to call anything at this resolution.

Here's the burst in an "idle pattern". In this recording the same pattern repeats over and over. Width of burst looks about .04 seconds.

In some cases, there are two bursts very close together or even overlapping, it seems. The PRR is the same (and the characteristic sound.) The burst width around .08 seconds is consistent with two bursts of the same ilk.

Now what would that be all about? What sort of data can be/ would be transmitted with a 7X4 pattern like this burst?

I would guess that it isn't a bugging device. There does not appear to be enough data for that. Beyond that I could only guess that it might be some kind of beacon.

Thanks. I don't know much about beacons. I found this:

"Beacons are primarily radio, ultrasonic, optical, laser or other types of signals that indicate the proximity or location of a device or its readiness to perform a task. Beacon signals also carry several critical, constantly changing parameters, such as power-supply information, relative address, location, timestamp, signal strength, available bandwidth resources, temperature and pressure. Although transparent to the user community, beacon signals have made wireless systems more intelligent and human-like. They are an integral part of numerous scientific and commercial applications, ranging from mobile networks to search-and-rescue operations and location-tracking systems. Beacon signals help synchronize, coordinate and manage electronic resources using miniscule bandwidth. Researchers continue to improve their functionality by increasing signal coverage while optimizing energy consumption. Beacon signals' imperceptibility and usefulness in minimizing communication delays and interference are spurring exploratory efforts in many domains, ranging from the home to outer space"

Couldn't find anything graphic about beacon signal design: waaay too much info on beacons but hard to find exactly what I'm looking for: anything recognizable as the same or similar signal. All the beacon signal images I found are single peaks.

Another odd thing, the receiver that picks up this signal is apparently being jammed: I turn it on, get maybe one or two bursts and then it is whited right out. The sound of it is pretty interesting: a "white-noise-ish thing" that gets higher and higher in pitch.. unfortunately it's hard to get a nice graphic that shows this. More mysteries...??

well, rcapper, many thanks. I reviewed my data and it looks to me like this is a probable navigation beacon:

maybe a signal that showed up in the frequency survey at 2632 Mhz, which is close to the frequency used by a ferry in the area.

there are two ferries in the system that often cross at the same time, back and forth to an island. The idle pattern would correspond to the time when they are both tied up. And the "double bursts" would correspond to the time they are both crossing. I reckon..

I have picked up the same or similar quite far from the ferry, in the city. My best guess is that it is probably a very typical navigation beacon, and the same type is operating in the port.

That puts that question to rest. Thanks very much.

Turns out it is not a marine beacon after all.

There are no marine beacons in the frequency range 1-3 Ghz here: they're in much lower bands and many are being delisted now, since GPS.

The ferry license at 2962.4 is not a beacon, and the ferry in question has not been in the area for some time as it was moved to a different service.

Here's a pure wag. Pure and unadulterated.

You live up north in cold country. Way down south here, our utility meter guys come around and read the meters, just as they have since time immemorial. Our water lines are six inches deep, and you just flip open the lid and read the meter dials. But I'm guessing that way up north in cold country, your water meters are inside the house, not outside, eight feet under ground to get under the frost line. So your meter guy would have to come into the house to read the meters, ... unless there was a small low power rf transmitter sending that telemetry data out as far as the street where he could pick it up just drivng by.

That may have nothing to do with your signal, but it's not a bad wag, eh?

not a bad wag, alright! give em a couple of years, everything will be set up with that convenience.. if there's money to put it in.

You're right, in town, the meters are inside the house. I don't know how they read em. I have a well here, so no water meter.

It could be Radar with IFF bursts, like from a plane/airport....

Yes, the first person I asked suggested a long range radar for air traffic. It wasn't the airport though. It seems like such a strong signal to be kilometers inland, I didn't pay enough attention to the marine possibilities.

Also the Raytheon rep here who would have expert knowledge of all sorts of radars in our area, he suggested it could be satellite telemetry. "Beacon" wasn't mentioned.

To a person with no expertise, the right word makes all the difference. If you don't have the word and the concept in your mind, you'll never find the explanation....

Take your field strength device and walk outside under your power line feed to the house. If the signal strength increases sharply there the unwanted signals are being conducted to your house via the power lines. I've seen this happen at AM broadcast frequencies. Just be sure you don't get fooled by 60 Hertz. Best of luck.

Thanks. The survey measurements were made outside the house as well as inside (and other locations). The power line runs to the house next to where I was standing to take the measurement. The measurements were 10 to 20 dB lower, outside the house and next to that power line. I guess that rules it out.

I also asked the power company about this, they came, checked the nearest transformer, replaced some connecting parts to the house "just in case" - they were very conscientious and helpful. They found nothing to suggest a role for power lines in amplifying RF in this case. Also they checked their records for some nasty power surges by time and date: there was no sign of these surges in the power system so the cause of that seems to be in house as well.

Okay, just to recap what we've discussed (many thanks to all) re: amplified frequencies 40, 102, 159 Mhz in house, and several possibilities to be considered:

1. Power lines have been ruled out. The power company found nothing: The survey data should show higher values in the outdoor reading, but the reverse is true.

2. Passive reception in the attic is a possibility to be investigated: does not explain high Q unless there is a very specific configuration.

3. The approx 20 dB increase in signal levels could also be produced by small 1 watt amplifier(s), which might also cause feedback interference if done a certain way.

4. Both possibilities 2 and 3 presuppose that there is an external transmitter somewhere, emitting the signal which is amplified. Identifying the source is ??? question pending.

Before my big excursion to the attic and/or getting an electrician in to do an inspection, I hope you can help with these questions:

1. I would like more information about small Class C linear amplifiers and their installation. If this was to be done covertly: is there somewhere specific in the wiring that such a thing would be placed? ie near a switchbox? on a wire that is the right length and/or orientation to act as an antenna? In a light fixture? If I know where to look, maybe it won't matter that I'm not sure what I'm looking for?

2. If an amp was to deliberately cause feedback interference, how would it be installed differently?

3. Pictures of 1 watt amps on the internet look big enough to find easily. Any comments about other versions? lower profiles? What's the lower limit of the size I'd be looking for?

4. With respect to passive reception by wiring, is there any way an electrician could test the wiring for frequency specificity? I reason that the configuration of wiring might ???somehow spontaneously produce the high Q observed in the readings. Is there a way of testing this?

Another thing I forgot to mention is a very strange combination of pipe noise and - apparently - audible radio signals. Hot water radiation system so lots of pipes. Pipe is metal so I should check the lengths of these as well as wires re: passive reception. Would pipe be the same as wire: as in simple length measurement for antenna frequency?

I found the file with the original data from the area survey, FYI I will try to copy it in here: Surveyed with Spectran 6060

RE: specs of Spectran 6060 and antenna used: I wasn't able to get the specsheet because the model has been through several revisions. The hyperlog antenna used was packaged with the device: it was either the Hyperlog 40xx or the 70xx. Manufactured by Aaronia.

RE: Possible Signal Sources in the Area: Here are distances and orientation of conspicuous radio sources.

The hyperlog antennas start at 300 MHz or higher. Your "questionable" measurements (where amplification occurred) are at 40 and 102 MHz, well below the range of that antenna. And that antenna should have been very inefficient at those frequencies: had you used a correct antenna, you would have received a much higher signal!

There were a lot of strong signals on the lower end. Difficult to give a measurement though, because there seemed to be this aliasing problem with Spectran.

I have this other counter, a Mitronics 1028 which also picked up strong signals below 30 Mhz. The Mitronics is different, it just reads the one strongest frequency and will lock on to it. I've watched it lock on again and again to ever changing frequencies below 30 Mhz, never repeating twice. Maybe frequency hopping or something of the kind. Also, the Mitronics would often lock on to zero Mhz and then you'd hear the gate speed increasing - seemed to happen in response to too much signal here in the house.

I have assumed that these frequencies 1 to 30 Mhz were very busy due to licensed activities and that this level of signal may be normal. Airlines and aviation for example use this band.

? Think I'm being irradiated ?? I'm wondering if insulating the SE wall of the attic would help.... (we live in hope....)