How They Know What You're Listening To On Your Radio!
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www.flickr.com/photos/coldwar... - วิทยาศาสตร์และเทคโนโลยี
Imagine working for TV licencing and going to all the effort of triangulating an unlicenced local oscillator, knocking on their door and saying "Hello, I'm from TV licencing, can I come in?" just to be told "No."
I am something of an anglophile, and was actually shocked to learn about the TV license, and the "search van" hunting for unlicensed TVs. I mean, Damn... Honestly, I have a like for the people, the armed forces (spent 2 wks w/RN), and some of the most beautiful camping in the world. Not so much the political stuff.
Back in the day you needed a license for radio or TV reception. It was The Post Office Radio Interference Branch back then and they did have more powers than the TV Licensing mob.
It's a fact that TVL have never used "detector evidence" in any court proceeding and give the explanation that to do so would reveal sooper-seekrit information to the defence about how it worked and its capabilities. You don't have to be a conspiracy theorist to think the alternative explanation is more credible. That it either doesn't work at all and it's all bluff or it does work but not to any degree of accuracy a court would be willing to accept as evidence and it's mostly bluff. I tend towards it being all bluff and even though it is, or at least was, technically possible it wasn't worth the time and expense so it was all bluff.
I haven't owned a TV for over 20 years so I don't concern myself with the subject any more but TVL were sending out leaflets that claimed their "hand-held detection technology" was so sophisticated and so secret that it was designed by two teams neither of who knew what the other was doing... Yeah... Pull the other one TVL.. It's got bells on. As if designing cutting edge devices works that way.
Here is something Rather sad but true..
When I worked for RADIO RENTALS, I initially earned my stripes in a Bucket Shop.. Churning out EX RENTAL TVs etc..
Every Thing we sold had a "FREE" 3 MONTH WARRANTY... FOR ABSOLUTE FREEE!
All the customer needed to do was register their NAME, ADDRESS and POSTCODE for a Possibly illegally poor warranty for 3 months....
Even though they probably had 90 days by Consumer Retail Laws anyway.....
The whole agreement was that when Buddy bought a £20 14" Nearly Colour Portable Ferguson...
THORN EMI... Would log the Name and Address and Postcode with TV Licensing!
Greasey
@@xxxggthyf It's pretty common knowledge now that the vans never worked technically. But they were a great marketing tool, so their value was somewhat valid, if not technically incapable. Imagine being a TVL van crew knowing that you were effectively an actor... lol
I knew they were monitoring me as they kept giving it away by announcing "You are listening to Radio 4 ........" - now I've had it confirmed.
Underrated comment
Back when I was 14/15 I discovered the local oscillator leaking RF at the 1st harmonic 10.7mhz above the tuned frequency on "VHF", so a radio tuned to say 90mhz would transmit at 100.7 a blank carrier. By exploiting this feature I was able to set up an FM pirate station by opening up the radio, locating the oscillator, attach an antenna and modulate the carrier with music from my 3 in 1 stereo, all the neighbours would tune in...those were the days my friend we thought they'd never end.
Gonna go drink a beer and listen to Mary Hopkin tonight.
I had a Karaoke machine that blew some electrical part and started transmitting on an FM station. That was fun with it's tape player and built in microphone. A whole radio studio in a box. Even portable if you had enough D cells. 😂
I think you mean 10.7 MHz and 90 MHz. Megahertz. mhz suggests millihertz although that would actually be mHz.
😢
@@-fuk57 My uncle Dated Mary Hopkin, from Pontardawe, Swansea haha
In the early 2000s two detector Vans used to park up overnight at the fire station I served at. We got quite friendly with the operators who used to pop in for a cuppa before starting work, they confided in us that the Vans were all bluff ! Not believing them they showed us that the Vans were indeed empty of anything !
The main culprit in modern electronic TV are the computer (an ARM chip) clock circuit, and the backlit LED driver. But those signals are drowning in a plethora of clock signals and switching power supplies present by the dozen in any house nowadays. I have problems listening LW band for this very reason. The Powerline adapters, which send Ethernet over the main power line, are a work of the devil, as they radiate powerful harmonics up to the 10 meters band!
Thank you for the video, was a trip down the memory lane...
I am trying to listen to radio caroline from home on a hot GEC AM/FM radio from the 70's known to be a great MW performer. although the freqencies either side of caroline are dead quiet in the daytime, when i'm smack on their 648 khz freqency, i can all sorts of squawks, and constant crackling about their weak signal from 160 odd miles away. wish i could recieve ONLY their signal ...
Brilliantly researched, as usual, Lewis. Truly the Mark Felton of radio geeks!
The German WW2 submarine service was absolutely paranoid about local oscillator radiation - by mid 1942, they'd issued directive after directive on radio procedure and even banned the use of the military issue 'civilian' type broadcast receiver that was issued to U-boats to amuse the submariners (the output could be interfaced with the boat's PA system so the crew could all be entertained) except when the vessel was in port. The Kriegsmarine SIGINT people believed that the LO on this non-military designed radio was particularly leaky.
Could D/f be used on a specific radiating LO signal from an operational U-boat? I think it could. The principal sub command net was hosted on a powerful permanent LF/VLF transmitter at Lorient, France, on Brittany's Atlantic coast, which operated on a fixed frequency. Furthermore, U-boats carried a standard complement of radio transmitters receivers (some with their own D/f capability) so, 99% of the time, listeners to Lorient (of the naval rating, Oberfunkmat, U-boat type, anyway) were using exactly the SAME type of receiver. - and therefore, identical LOs. The Allies by this time had captured enough U-boats to understand this. Knowing the receiver IF and also the frequency of the incoming transmission, means that the likely frequency of the radiated LO signal is exactly known.
Sure, the power of the radiated LO signal will be extremely low. And, in fact, the U-boat receivers DID use an RF stage ahead of the mixer. But, those valve mixers (triode/hexode or pentagrid) are unbalanced and provide nil in/out port isolation, so SOME of the LO will be radiated regardless of the RF amp stage. Remember that this is a LF/VLF signal which will propagate via ground wave - and over a highly conductive (seawater) surface will get a considerable distance. The idea that an aircraft within a few kms could accurately detect this easily identifiable signal (and home in on it) isn't so fanciful.
However, LO radiation wasn't really the U-boaters headache. It was a red herring - but a herring that also caused them to abandon the R600A 'METOX' 200MHz aircraft radar detection receiver device on the same basis, 'vulnerable emissions'. Had they known about British HF/DF detection and most importantly, Bletchley Park's penetration of the naval Enigma, they would have lost interest in local oscillators completely.
Oddly I was just reading about an anti-ship missile that does not use radar so it can operate in stealth mode. So it is not just ships - you want you missiles to go undetected too.
Love this highly accurate and detailed comment.
I love reading things I really don't understand. Good job on you, nerd. That is both a compliment and a derogatory.
I saw the inside of a detector van in the early nineties. Except for a crisp packet, it was completely empty.
You were misled...
@@wigglepig115 by what?
@@opts9 whilst it true that *some* of the vans were dummies (for purposes of research) there were a number of real, working setups (more than two and fewer than twelve.) The equipment was/is complicated to operate, extremely costly and not completely reliable, especially with the changes in radio designs in use.
@@wigglepig115 yeah, I can believe it.
@@wigglepig115 absolutet rubbish
Fun fact: I do believe that even though you had/have to supply a name and address when buying a TV, for licence purposes, neither you nor the retailer were obliged to prove that address was correct.
Cue thousands of TVs being watched in 10 Downing Street, by Mickey Mouse.
Fun fact: you're not obliged to pay the TV licence as you don't watch live TV. ;)
@@snuggleseal indeed, they are exceptionally good at sending 'threatening' letters (no joke, at least one a month for the last 9 years), some what less good on actioning the mentioned visits... Which is a shame. Even made it 'easy' for them with a telly in the front room.
(disclaimer : I don't actually watch telly, at all, but why do *they* need to know that...)
Buy a nearly new set from a friend :-)
I have only recently come across this Manchester Ringway site. As an ex Eccles stonian now living in Australia and a very long time ago a JET (Junior engineer in Training) at Winter Hill ITA transmitter. I found the article on Winter Hill first on a nostalgia search most interesting and surprisingly accurate. I was there during the effects of the Emley Moor mast collapse and the implications on the Winter Hill mast.
I was on my basic training course at Marconi Chelmsford when Emley More actually collapsed.
Exciting times as colour for ITV and BBC1 was being implemented. How technology had moved on in the last two decades particularly.
Local oscillators send a carrier wave further than you would think. Back in the 80s a friend used the oscillator from a grundig transistor radio and just by attaching an fm dipole at the coil and feeding in an audio output, managed to broadcast over half a mile.
German WW2 uboats were equipped with a radar detector operating in the VHF band used by earlier Allied anitsubmarine radars. The detector was called Metox and it was a superheterodyne receiver.
"Metox also emitted a weak signal, a property common to many radio receivers, especially superheterodyne receivers. In an indirect way, this had serious consequences. In the spring of 1943, the U-boats suffered badly because of the introduction by the British of a 10cm ASV radar. But a captured British officer told the Germans that their misfortunes were caused by the transmission of Metox, which were detected by Coastal Command aircraft. After verifying that this was technically possible, the Germans believed the story. This delayed the introduction of Naxos by some months, during which the U-boats suffered heavy losses."
Naxos was a newer radar detector built to detect signals with wavelengths between 8cm and 12cm.
Luis Alvarez, who later proposed the asteroid impact K-T extinction theory with his son Walter, realized that U-boats' radar detectors non-directionally measured the signal from the airborne search radar. Since the radar pulse drops with 1/r2 and the return also goes as 1/r2, adding a circuit reducing the transmitted signal by 1/r3 during an attack run would still allow the return signal to get stronger during the approach- but make the signal detected at the U-boat decrease as 1/r. This spoofing lulled U-boats into to staying on the surface to run their diesels since the radar always seemed to be going away...
Our local cable company (USA) would drive a windowless van through neighborhoods during TV prime time...the rumor was that they were looking for people watching scrambled "premium" channels that weren't paying for them. Showtime could be descrambled on an old Atlanta Scientific push-button cable tuner by depressing the "3" and "7" buttons together 😂 (note-it required taping the buttons down, as the spring mechanism would release when two buttons were simultaneously pressed!).
As someone who worked for Time Warner Cable as a Technician, many cable devices have backdoor menus usually for testing purposes. You could also get 3rd party boxes that de-scrambled channels, you can still buy them today. The cable company was more concerned with illegal cable connections outside than anything that happen inside your house.
@@TheBaldr The FCC fines cable companies if they allow their cable connections to leak their cable signals out, so many company vehicles have alarm devices that monitor a single fixed frequency CW signal on their cable system. I am sure that is all that is happening where I live, your mileage may vary. Ron W4BIN (in Florida)
@@TheBaldr two different systems. With the antique mechanical tuner box, "scrambling" was via interference and paid subscribers got a notch filter to filter out the interference. Scrambling, I have a network tuner that can descramble the cable signals, if I purchased the subscription and QAM card. I'm sure there are similar that are dummied to not require the card, but I never bothered trying them.
I only needed the network tuner so I could use MythTV to legally record my programs I wanted to watch.
There was a similar system used, in the States, in the 1950s. At prime time, a detector van would drive around a given neighborhood w/ a system to detect which households had their sets on. But not only that, they were also able to detect which channel the sets were tuned to (presumably via the harmonics). These were tallied up for the TV ratings.
they could pick up the local oscillator for the TV, TV sets had a standardised I.F. so it was easy to do.
Wait a minute, you mean in Europe you had to supply your name and address to buy and use a friggen TV? Talk about government overreach!
Yeah, but not to find violators with unlicensed TV, since no license was required in the US. At least we did something right.
@@houstonfirefox You have to buy a licenses also.. that is FU.
@@houstonfirefox Worse than that you need a TV incense £160 a year for the BBC service, even if you don't watch there channels & it's enforceable with prosecution. Don't call it Auntie Beeb for nothing big mother is watching.
Good thing is that you don't get any adverts on BBC. I think its a archaic business plan should be able to opt out , like Netflix & other subscription services.
In South Africa we once made an oscillator that ran off a 9v battery. We tossed it into various trees, the signal being so strong it would swamp their equipment. We seldom had much trouble with them after that.
Swamp whos' equipment?
Great video. I was about to mention 'Spycatcher' but you beat me to it! It reminds me of the time I discovered - completely by chance - that by mixing the radiated LO carrier (or a harmonic of it) from a nearby valve mediumwave radio, to my portable, Marine Band radio, I could resolve SSB and CW transmissions from radio amateurs on 160 and 80m. I was chuffed (I was 10!)
Yep. Been there, done that. I used to resolve ssb on my cheap Niponease multiple waveband portable by putting a MW receiver alongside it
I did it too.
G4GHB
Although I understand why licensing of radios and television sets was implemented in the UK, the whole idea of pay radio sounds strange to those of use who grew up in America. The rule of thumb here is that if it's coming through your airspace, then you're free to listen... unless, of course, you're using equipment designed to illicitly decode secure government, military or financial communications. You can get in a lot of trouble for doing that and rightfully so.
This channel just gets better and better. I'd like to see a video about the first Freebanders.
Honestly appreciate the ‘plain language’ and analogies. Not a radio geek since the 60s. You brought together your research, visuals and knowledge in an explanation a layperson could comprehend. Really enjoyed it.
I was in the police when these vans were in use. They were simply transport to take the TV licensing officers to the next batch of addresses and frighten the locals into paying. Detection was 99.9% people confessing on the doorstep. We used to reluctantly enforce the warrants.
It still is 99.9% people confessing on doorsteps, the other 0.1% is the enforcement goons twisting people's words into confessing. And they don't use the vans anymore, they use their personal cars. Whenever someone questions whether they have business insurance on their vehicle, they quickly drive away.
Ah, yes. crown enforcers all the truths coming out now, you will be judged .
It's still 99.9% detection from doorstep confessions.
They have no right to access your property
gestapo 20xx and beyond
Back in 1994 at work a FM table radio had a local oscillator signal strong enough to appear on the screen of a spectrum analyzer what was testing a FM broadcast interface for a rear window antenna intended to address high interference in Detroit's Greenfield Road test course due to the many radio stations there. Broadband field strength at Greenfield was over 500,000 uV/M! Two FM stations even created cross band suppression of a AM station at 590Khz!! (The table radio at work was 200 Ft away from the lab! Finally, a shielded room was installed.)
I never saw the point of Post Office detector vans. Post Offices aren't that hard to find!
They are these days down our way.
It's more of an old school problem. They had to use those big vans because the equipment was so big and sometimes you may need to carry auxiliary power (which requires more room). Finally they are still used today but I believe only for longer stake-outs, but often times they are just resorting to "dead cars" that are just wired to the teeth.
All our TV here in the states was supported entirely by advertising with the exception of PBS which was mainly supported by viewer donations. Beyond that, any commercial free TV that was available was on cable TV like HBO which we had to pay extra for.
So in the UK you pay for the right to watch TV and still have to watch adverts...total BS. We get a lot of UK shows here in the states, wonder when the UK government is going to try to suck money out of us.
@@stevelaminack1516 - no commercial advertising on any BBC TV or radio stations. That’s what the license fee is paying for. But yes, if you watch a commercial TV station, you will obviously get the advertisements as well. However, generally (it varies slightly on the time of day) the amount of advertisements is limited to 15 minutes per hour. Most broadcasters therefore run up to 4 minutes of advertising four times per hour.
@@stevelaminack1516 no. In the UK you pay to own a TV capable of receiving non-commercially funded TV or watching said non-commercially funded TV on iplayer.
Hm. Though you may have a point. You pay money to virgin and sky right? And well those channels are full of adverts so yeah I guess you do pay money to watch adverts on TV. Just it isn't the BBC or the TV Licence, but your Satellite or Cable sub.
I’ve heard that the Cat Detector Van from the Ministry of Housange could pinpoint a purr at 400 yards.
Was that the van which had the word “Dog” crossed out and “Cat” written on in crayon?
So what you’re saying is that in the 50s, one of the major ways you could detect the presence of a TV or radio inside a home was the electromagnetic radiation coming from its antenna, but in the visible spectrum. Worse yet, the leakage was present even when the device was fully turned off!
Redifusion set up a large cable undertaking here in the south east essex uk in 1964 it closed the antiquated 5 channel system in 1997 due to competition from the superiority of the the multichannel vrigin media system ...in late 80s though they introduced Premier movie channel .£10 per month ..but my friend noticed that all they encrypted it with was a simple signal that they removed with an inline notch filter at your end ...so a few electronic buffs soon copied these filters / pcb .....lol.....and sold them in local pubs ...for £20 sovs
Or £30 sovs if you wanted the fitting service x
Halfway through writing the spycatcher comment when you mentioned it 🤣 amazing that they had planes fitted with the RAFTER system, never mind vans.... but it's also the start of the 'white van outside listening to me' trope that started in TV and movies, All the early vans were white as they needed to be made out of fibreglass, and white was the only colour they could do it in and still have it look like a metal bodied van afterwards. Weird how a little detail like that goes on to spawn a trope that's still being used today
Thank you. I've often wondered if that were possible - yes it is!
Looking at the intermediate frequencies generated by amateur radio equipment I think it might also be possible to identify which make and model (in some cases) is being used.
No need for a TV licence anymore 🙌
No need for a TV at all. The content broadcasted is not worth it.
@@dave161141 how can you say that........Re-Repeats of Bargain Hunt are worth every penny
really informative and an enjoyable watch, cheers M7SPI
As an American I cannot even imagine getting in trouble for having an unlicensed TV. While in the US Navy I knew that during the Vietnam war, we could tell when a receiver was turned on within 50 miles, we could even tell the brand of the radio.
And the audio volume.
I can't imagine paying a fee just to watch over the air broadcasts.
@@fungo6631 How many dense apartment blocks do you think are at sea or in a backward jungle coastline from 1600 meters? I was in radio one behind a door that you had to put your hand in a box and push the code buttons to enter and a marine guard checked you for access. I saw the equipment but was not an operator of ECM, my job was cryptographic machines. I was friends with the ECM people and believe them. I saw some of the signals on the scopes, and even took apart some signals myself. I was told that besides jamming we could receive a radar signal for instance, modify it send it back to the enemy radar and change what they see in their repeater. BS if you want, do all the math you want, I saw what I saw back then in the late 60's in Vietnam.
In Germany the monthly fee for a car radio is $20.
@@grandrapids57 That to me is a sad joke. I would guess there are a lot of holes in dash bords.
I missed this first time around & just found it.
So many people think detector vans never worked but I had a run down of how the detection vans worked & got to see inside in 1984.
Then they got decommissioned in 84 to be replaced with fake vans looking for just the masts.
I was told at the time that the newer TV could not be detected so days was numbered This also gave me an insight into why you could not share a TV aerial as before the filter design change they would interfere.
Like the end of the detection vans so did my apprenticeship but the first few weeks I learned so much before leaving. I was NOT going to be part of the detection team but the same company.
It still BLOWS MY MIND that there are places where listening to a scanner is unlawful. I have had a scanner on in the background almost constantly since the late 1970s. (I actually have TWO running right now, one for local police and fire, the other sweeping CB, GMRS, FRS and MURS for entertainment, LOL) in Pennsylvania (USA) Scanners are as "regulated" as any other radio RECEIVER. In other words, using a scanner here is the same as using a "normal" AM (MW)/FM or SW radio! Also of course our over the air (Broadcast) TV and Radio is ad supported and thus is free to watch or listen to without a license, In fact the local TV and radio stations want AS MANY listeners/viewers as possible. Back in the 1970s I got a pocket AM radio for FREE while attending a baseball game, The radios were being handed out by the radio station that carried the baseball games!
A friend retired as a cop and got a job driving the detector vans. This was around 2007 if I recall correctly. He told me the van was in fact empty by then and his job was to drive round areas and park up for 10 minutes at a time to be sure to be seen.
hi lewis i can remember the old 405 line tv set,s from the 70,s they used 6 meters back then i lived high ground near bath we could get atv southern westward and at times thames tv many moons ago now thanks m3hnl warminster cheers lewis
When I was in the Army training at Fort Devens, MA, the barracks I lived in had people who would tune in a local AM country music station and blast music in the barracks. I had to use earphones with my radio so I could hear the station I wanted to listen to. One day the country music was very loud. I was tuning through the AM band to check out what AM stations I could hear, when I heard a faint whistle grow louder in the country music until it was almost all that could be heard on the other guy's radio.
The whistle grew quieter until it disappeared as I continued tuning through the AM band. When I turned the knob and tuned back, the whistle returned to the other radio. The guy changed to a different AM station and turned the volume up even louder. I tuned back and fourth across the band until the whistle appeared on the new AM frequency. When the other guy found he could not make the whistle go away, by changing radio stations, he turned his radio off and put it away.
It was years later that I found out that the local oscillator of my radio was transmitting a signal that interfered with the other radio, causing a heterodyne noise, which was the whistle. Even though I did not know what it was or how it was happening at the time, I realized that I was jamming the other radio and used it to good effect. Whenever someone turned up the volume of their radio to an annoying level on an AM radio station frequency, I would get my radio out, put earphones on, and tune around the AM band until the heterodyne jammed the other radio. In a short period of time the other radio would be turned off. I also found out that it only worked with AM radio stations and not FM.
the detector van thing was a case of "they could detect" but in reality it was all a visual threat and as it worked so well in the early days they had no need to actually do any detecting.. the old 405 line aerials were huge too.
Maybe they could pick up some electromagnetic harmonics, but there's no way they could pinpoint a single household in a flat (as measured from the ground with a handheld antenna no larger than 1 foot), and determine with 100% certainty that they were watching Columbo.
i still see the occasional one rotting on a half fallen down pole of someones chimney .
@@SuperCanuck777 you have to hand it to the original manufacturers of those H aerials, they were pretty robust :)
@@amojak Yes. heavy duty thickness alloy unlike now. i salvaged one of those vhf low H antennas and used the element brackets to make a 3 ele yagi for 27mhz which i spoke all over the world on in 1982.
They used a directional microphone aimed at your living room window. Listened to what you were watching/listening to to use against you on the doorstep and get you to pay up.
Exactly, until the Investigate Powers legislation of the 1990s made this illegal unless authorised, on a case by case basis, by the Home Secretary.
I think it's hilarious how in North America, and many other places where no idiot tax is collected that electronic technicians call bullshit on the whole tv reception detection equipment and propaganda spewed by their respective local authorities. I asked my dad who is a certified electrician and electronic technician who used to service radar equipment (of all things RF). We spent several hours with RF detection equipment trying to catch the famous "European LO leak" and get this YOU CAN'T DETECT ANY RF LEAK FROM THE MAJORITY OF TV SETS OF THE 80'S AND 90'S. We tried for hours on 8 different tv models. The only one the leaked any RF was an old Hitachi from 1977. It could only be detected up to 6 feet away max. So, detection vans are only propaganda to justify stealing money from people so they can keep doing bad things to children.
Great video,thanks,I never thought about the IF stage leaking. None of the techniques you described would work these days as the noise floor or EMI in residential areas is about S6 to S9 due to cheap electronic appliances and solar panels.
Do solar panels create any inherent EMI, or is it due to the inverters?
@@galfisk All electrical appliances with switch mode power supplies generate electromagnetic radiation however there are regulations on how much radiation they may produce which is all good and well.
A Tridactylidae's don't make a loud noise but when are thousands of them, the noise is deafening.
The EMI from appliance has the same effect when there are thousands of them on at the same time. Ask any armature radio operator that lives near high voltage power lines what level the noise floor is.
Fascinating!
Fortunatly TV licences were abolished in Australia in the early ‘70s I think by Whitlam, I remember a TV ad which showed a man furtively watching a TV and then he gets a knock on the door.
I recall it was $12 a year and included all radios not just TV and you paid at the post office. (PMG).
THANK YOU ,NICE WORK,,LOVE THE HISTORY,,, DES CREAN,BELFAST,IRELAND
I am surprised to hear that people have been prosecuted for listening to transmissions. Here in New Zealand, there is no law against listening to anything. Basically if you can hear it, good for you. The only thing you are not allowed to do is act on any information you hear. For example, if you hear that the police are about to raid your neighbour's place, you're not allowed to call them and tip them off.
as was the case in western australia until recently
@@andrewsmart2949 What was Australia's position on this? You say "until recently" - what changed?
Digital encrypted now
Worcester police made threats against me for alledgely monitoring them in the late 90's before they moved to digital. mind you every man and his dog was eavesdropping on them for entertainment purposes and worse back then.
@@sw6188 they changed the law and made it a seroius offence
SWIM modified a Walkman in the 90s to modulate the IF and would play their own music over restaurant radio PAs that they patronized. Of course now everything is Bluetooth. The good old days.
Across the pond in the 'States', there was something called "The Tempest Standard", also known as Van Eck phreaking or radiation. Specialized equipment was used to detect leaky signals from CRT Displays, such as TV's or Computer Monitors, & display them on a remote display. With the right equipment, this was successfully accomplished from a respectable distance, unbeknownst to the surveilled individual.
Yes, but to be fair, that technology was intelligence state level and would certainly not have been shared for the GPO to put it in a Sherpa van on the mean streets of Manchester... lol
Very different to LO detection and with different end-game. What links the two? Peter Wright does.
I once had to design a power supply to the TEMPEST standard for a military application. When I asked how low I needed to get the emanations I was told "We can't tell you, it's secret".
Been there. Done that. Ridiculous. [Redacted as I signed the official secrets act.] :-)
A chap I knew talked a bit about the wiretaps he did, while in the employ of the local phone company. Mind you, this was back in 1970's & 80's, so technology was slightly primative, when compared to today. He worked in one of the central buildings.... the type with no windows. Anyway, he would wire to the 'suspect or marks' line, and then tie it to another line, which I'm told lead to a local govenment building. Essentially, the government types got an extension on the phone line of their 'person of interest', without going near the place. There were other configurations, that used tape recorders or monitoring services, commonplace at the time. It was less 007-type work, & more 'tight-lipped' electrical/telephone work.
Genuine thing: just outside a supermarket in a carpark in Oxford back in the late 90s when I was a teenager, I spotted a rather conspicuously parked "TV detector van" (fairly near the shop's entrance, but not too close). I remember one mother commenting to her child not to go close to the van with the blacked-out windows.
I on the other hand was both far too curious and was prepared for any consequences. Sure enough as I suspected just with a bit of life knowledge from the shape of this vehicle, when I cupped my hands on the side window to block the outside light to see into the van it was just a regular minibus. A classic bit of propaganda.
Of course TV licence "detection" is mostly done by having to register your details with the retailer at the point of sale and of course the rare visit from the licensing people.
My Mum (God Rest her soul) used to work for the GPO as it was then, she told me the old "comma" vans at the Norwich Depot had 2 chairs, a table, a transistor radio along with a large flask of tea for the "operators", no electronic gear whatsoever. They would often drive around and park up on an estate , then stop while the Football was on.
Bloody hell i have a lot to learn about radio! Lost in lingo in just the first minute :) Just got my first handheld, the uv5r. Cheers, subbed :)
i think there are flaws in the circuitry of the receivers that the police can detect such as the local oscillator and the oscillator used to set up the cancellation to extract the signal.
there was a device back in ww2 that was supposed to go between the antenna and receiver that would block the stray signals from coming back out to the antenna so you could listen in secret.
interesting about the tv vans and how they "worked" but im not sure as there has been no court cases (as far as i know) where evidence gathered by a van has been used and theres anecdotal evidence from ppl that used to drive the vans saying they didnt work it was all fake equipment , they had a list of houses that didnt have a license and they just drove down the street looking for at first an aerial and then the flickering light from a tv and reportedly turned a tv on inside the van and just went through the 2 or 3 channels until they matched the flickering seen through curtains when matched they knocked on the door of the target house and i was told by a salesman that the uk in the 70s and 80s had to report the addresses from tv sales to the relevant body at the time.
came here to comment about spycatcher, but you got that. 10/10 there technique of listening to the LO and broadcasting on the frequency of interest and hearing the LO "squak" ment the reciever must have been listening to that frequency. super cool
The technique was called Rafter (Wright), I've used it before some years ago. But have had little success with modern kit. In the modern urban RF environment without knowing what the target is monitoring and what kit they're using, Rafter is very difficult.
We never had to license our TV's. We wouldn't have stood for it. I realize that conditions were much different during the war in Britain, but even our power grid now emits "broadband - over - power - line" interferences because the power companies just got lazy and didn't want to pay a meter reader and so set things up to read meters remotely. A Ham Operator has to endure so many illegal signals that sometimes we receive nothing but illegal interferences.
So, one day I had had enough. I put a low frequency bandstop filter on the incoming mains, and then searched out every switching power supply there was, and replaced them with transformer operated power supplies. Did it get rid of all the noise on my receivers? No, but after shooting out a security light often enough with my airgun, they finally gave up on it. No noise anymore. I imagine that I had pretty much the same equipment that your "post office" officials had to search out all the offending noisemakers. In America, Ham Operators police ourselves - and others. Those who do not cooperate are taken care of.
You sound like an old man yelling at clouds
Yeah, but he's right... there's so much RFI at my place that SWL is almost not doable. 10 over power line noise. And I unplug or turn off terminal strips on wall warts and battery chargers, otherwise the noise is full pin.
I rememeber this forn the ham school study, i almost forgot this. thanks.
We had a similar scanner van thing apparently here in Sweden, though when my mom worked there (Radio & TV controller) some 10-15 years ago it was more of a prop then anything.
Nowadays we don’t have any fee though, after they changed so it became a tax instead and every single person has to pay since a few years ago.
Thanks Lewis
As you know Tempest proofing both buildings and kit was big during the Cold War. A principal driver for these efforts was the knowledge of just how much information was being gleaned from Soviet bloc kit. Nothing was covert in central London, the I.F. receiving aerials were just impossible to hide. The easiest to spot were between the buildings on Church Street and Kensington Palace Green/Gardens;with the obvious data sources being the various Soviet bloc buildings lining the private road. Top left side of any southbound bus gave a grandstand view if you were looking - very few were. These were very large vertically polarised aerials with limited swing. After the Cold War ended the site became a large housing block with eye watering service charges. Regarding information in the public domain:- Wikipedia has a Tempest category which covers a wide range of topics. Remember to check the edits log for some of the information submitted by the public.
Very well played my friend a video time of 555!
It is possible to determine the frequency a radio is tuned to by picking up the local oscillator provided you know the intermediate frequency. Standard intermediate frequencies are 455KHz, 10.7MHz etc. If a receiver was constructed with a really unusual IF then the local oscillator could still be picked up but adding or subtracting the usual offsets will give the wrong answer.
Yep! I used to work for a company making radio mikes and their receivers (I did the fault finding on UHF front ends and first and 2nd IFs) and where multiple units were going to be in use together different first IFs would be put to use to stop cross interference using anywhere between 10 MHz and 12 MHz (roughly - I don't remember exactly)
Using a very primitive set up with just a short wire antenna and an RSPduo SDR, I can pick up the LO from a small handheld MW radio about 5metres away - so not much. Has anyone any idea of the range with a more optimised set up (good directional antenna, LNA and a professional spectrum analyser)? I imagine that tube receivers with an attached outdoor antenna were also much better radiators.
We could detect this type of signal from a little more than 50 miles away with our shipboard ECM gear.
@@AdamosDad Thanks, I'll assume that that is about as good as can be obtained if ECM equipment is used.
Imagine being required to have a license to watch television. The only thing harder to imagine is an "official" visit because you're watching television.
I’ve got this book and read about this! There is a additional book to this one.
For AM radio, a tuned RF radio can be made to work very nicely. As frequencies get higher, it gets harder to amplify the signal. This is a reason to convert it down like you described.
Also some car radios and a few others used a 200KHz intermediate frequency instead of the 455KHz that was normally used. This made the radio cheaper to build but they had more problems with a strong station stepping on a weaker on.
Your FM radio and your very early TV set likely used 10.7MHz as the intermediate frequency. The standard moved it up to something near 45MHz.
Using 200 kHz for IF in a radio used in the UK would be interfered with by the BBC's 200 kHz long wave transmitters.
@@HansWHoefnagels 200KHz is kind of rare for broadcast around the world.
@@kensmith5694 That why I mentioned the UK.
@@HansWHoefnagels Yes, it makes sense. The only 200KHz car radios I have seen are US only as far as I know.
WOW,I DID NOT KNOW RECEIVERS EMITTED A EMISSION..THANK YOU
Thats a shame they went after scanners. I'm in a rural area in the US and they are essential for us farmers who have to fight fires too. Super useful to be able to hear the FD about how a fire is progressing or to hear what they want to do with air support.
That's a Hammarlund HQ-120X receiver in the center at 2:50. It had an RF stage which isolated the oscillator from the antenna.
Very interesting yes.
Always thought TV/Radio detector vans were just a ruse - thanks for explaining!
Another very informative and interesting video.
73 M7TUD
I thought you were Jason Manford when you started speaking :) Thanks for the video!
I had no idea there was a TV mafia in the UK
By accident I found this out, I was listening to npr on my radio and I found a weak npr station in the kHz range. Couldn't figure any harmonics for 81mhz then I tuned the radio and realized it was the intermediate frequency stage in my receiver. You could drive around listening to that most radio use the same IF
This video makes all of the Monty Python sketches about detector vans make a LOT more sense now..
Peter Wright: Spycatcher. They had/have it in the MI5 too, they called it RAFTER.
Imagine back in the day the lengths people would go to to avoid detection and now we just give governments and corporations our most intimate personal data, our thoughts, feelings , our contacts list, our tastes in hobbies and pastimes, our finances and purchases and our political and sexual persuasions .....all through our phones. We give it up freely without a second thought.
Well because you all said I don't have any ting to hide... Bull s***. You have many things that you what to keep private... people don't need to know you private life...the government and private company's for what they want you information....i bet that is to make money from you or spy on you.... don't give up you private information for free...you have rights...and they don't have any business to know you private information...don't give them any ting...( Asked for what they need it..and say no you don't need it )
There's 1 reply to your comment... but its vanished !! Perhaps Big brother has removed it for some reason!!
Hi Lewis, on your summary you mentioned there are not more detector vans, this is not strictly true, there any many agencies who use similar systems just not solely for TV or radio.
What were the radio telescope dishes used for?
I’m an amateur radio operator and I had no idea about this!
Is that because you are not familiar with the superheterodyne principle and mixing which is how most radio receivers work?
I used to know what TV channel my neighbor was watching on his CRT-based TV since I could pick up the oscillators from his TV on my low frequency receivers.
For more modern (ish) techniques see Van Eck and Kuhn. Both did extensive research into similar stuff but post 1980s.
Hello: In your country you needed a licence to watch TV? (!!!). it is unusual today but in Argentina you just put an antena and watch some channels, analog and digitals. I still have them . Vans are very usual, filled pickig illegal FM Radios and use >100 m high antenae to investigate them. Cheers from frozen Patagonia.
The UK detector vans didn't actually have any working equipment in them - only tea and coffee making equipment and a chemical toilet.
So they say….but what they (whoever they are) say is usually incorrect
Back in the 1980’s when Australia has CB licenses the local radio inspector would drive around DF’ing 10.7MHz and 455kHz IF’s.
Foh kin hell 😂 all news to me! Hehehe.. Excellent video 👍
The TV detector vans from what you have said appear to work the way I thought. From various FOI requests, they still say they still work but I have a sneaking suspicion it all fell apart when PC CRT monitors, etc became common. Are you aware of any way they can still determine or should I say find out if you are using live TV? I ask this because in no court cases has tech evidence been submitted as far as researchers can ascertain. Thanks for the video as usual great content.
I dunno if CRT monitors would be that much of a problem. VGA runs at a horizontal refresh of 31kHz while TV broadcasts run at 15-16kHz, depending on the system.
How can they prosecute someone for listening to something? If they openly transmit unencrypted audio then more fool them.
I'll listen to what I want if it's open unencoded.
Thankfully in my country it is still legal to listen to radio.
Police in Australia used modified seized radar detectors to pick up the local oscillator of other radar detectors. No point having one your going to get caught and add more detectors to the pool. I did consider modifying one to detect the detectors.
Who was the comedian that said "watch out for the vans with the spinning roof racks" ? lol
Tony Hancock?
My antenna is outside, however my receiver is inside a pole barn. Would they pick up my receiver that is shielded by a metal pole barn?
Here in the US the radar detectors detectors do the same thing for the police looking for people using radar detectors on the interstate highways or any roads to drive above the speed limits.
I seem to remember a new scientist artcle that said the old TV detector vans worked on Van Eck radiation, which was the phosphorus of the screen its self re broadcasting the signal at a shifted frequency and slight time delay
Very interesting. Had no idea a license was needed for television back then.
2m26s Lovely to know you needed a car radio licence for £1 and 5s. Didn't know that.
Sherpa Van - A-reg. I used to drive one for the railway. Lucky they got theirs started each morning with all the kit inside!
And the bloke in passenger seat just has a list of addresses without a current licence. Let's just knock on Mrs Jones' door at number 29 while her husband at work and she'll spill the beans.
I don't know it it is true but in the days of TV detector vans it was rumoured that they could detect which programme you were watching by checking the synchronisation of the line scan stray field they were detecting with the transmitted line rate for that station. Thus eliminating false positives e.g. from early computer monitors made from tuner-less TV sets.
To answer some of the points in other comments…
The U.K. tv license is actually a tax.
The actual U.K. TV License operation is contracted out to a commercial company. It’s not BBC staff that get involved in the day to day operations.
Most of the time, the automatic computer generated letters go out regardless of your reason why you don’t have a license. Unless you admit to watching television, or you let them in, or they can see in through a window and see you watching television, they will have great difficulty prosecuting you.
Having said that, assuming you can afford to pay for a tv license, it is actually good value for money compared to commercial subscription tv or a typical mobile telephone contract that has a high data usage/allowance. And the money from the license funds the BBC. Whatever individuals may think of the BBC, they are one of the better broadcasters in the world.
Some money from the U.K. TV License fee has been used in the past for other public service broadcasters and for other television distribution equipment costs.
It was technically possible to pick up the local oscillator of (analogue) radios and televisions. And to pick up the line output frequency of analogue televisions. But as more and more houses got equipment, and as radio/tv equipment got better, it becomes more difficult to isolate which building the ‘transmission’ is coming from. Also the type of construction of the building has a significant effect on the strength of the signal that escapes…
It’s much easier to look and see who has an aerial… Or look in through their windows… Or compare the database of homes vs. registered licenses…
you know i never quite understood the fuss about licensing for radios and TVs in the UK. We originally had only one government channel, which was paid for from consolidated revenue. All other broadcasters were commercial stations respectively.. I refer to Australia, is this practice remain in place?
To be honest they can tell what your radio is tuned to when it is turned on, but they can't tell if you are actually listening to it.😊
I can't believe in this day and age, Britain still has TV and radio licences. We got rid of ours down under ages ago.
The Post Office detector van was a tool used to frighten people but of little actual use
I still cant get over the fact that in 2022 UK charges citizens for licences to WATCH tv or LISTEN to broadcast radio. In Australia 99.9r% of our laws are based on the UK/EU - I'm so very glad this is ONE thing we do NOT copy.
All the radio/TV licensing goes back to the great scam artist Marconi who got the post office to do his research and put his name on all the patents, he then got a cut of all sets sold (ten shillings I think) back in the days when that was a weeks wages for some then you had to pay a licence to listen to the thing or go blind trying to watch a rolling flickering image that disapeard at every opertunity.
Its to fund the bbc in most countries that is just funded with regular taxes.
The radio precept went away many decades ago, so there is no licence required to listen to the radio.
@@wigglepig115 ahh thanks for the correction
@@belstar1128 It is now but thats not how or why it started