What-If 0087: "Enforced by Radar"

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What-If 0087: "Enforced by Radar"

Postby Klear » Tue Mar 11, 2014 9:35 am UTC

Enforced by Radar

I've occasionally seen "radar enforced" on speed limit signs, and I can't help but ask: How intense would radio waves have to be to stop a car from going over the speed limit, and what would happen if this were attempted?


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I'm imagining that the sign guy is actually BHG without his iconic hat.

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Re: What-If 0087: "Enforced by Radar"

Postby Catharsis » Tue Mar 11, 2014 10:07 am UTC

If a cellphone exerts a billionth of a Newton, and it takes a trillion cellphones to levitate a snowflake, doesn't that imply a 100 kg snowflake?

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Re: What-If 0087: "Enforced by Radar"

Postby dalcde » Tue Mar 11, 2014 10:24 am UTC

Broken link in citation 2.
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Re: What-If 0087: "Enforced by Radar"

Postby Klear » Tue Mar 11, 2014 10:25 am UTC

dalcde wrote:Broken link in citation 2.

Works just fine for me...

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Re: What-If 0087: "Enforced by Radar"

Postby mustermark » Tue Mar 11, 2014 11:57 am UTC

Newton of pressure? Lolwut?

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Re: What-If 0087: "Enforced by Radar"

Postby chalkie » Tue Mar 11, 2014 12:09 pm UTC

The last picture reminded me of an old story...

Two British traffic patrol officers from North Berwick were involved in an unusual incident while checking for speeding motorists on the A1 Great North Road. One of the officers used a hand held radar device to check the speed of a vehicle approaching over the crest of a hill, and was surprised when the speed was recorded at over 300 mph. Their radar suddenly stopped working and the officers were not able to reset it.
Just then a deafening roar over the tree tops revealed that the radar had in fact latched on to a NATO Tornado fighter jet which was engaged in low flying exercise over the Border district, approaching from the North Sea.
Back at police headquarters the chief constable fired off a stiff letter of complaint to the RAF Liaison Office. By return came the reply in true laconic RAF style:

"Thank you for your message, which now allows us to complete the file on this incident. You may be interested to know that the tactical computer in the Tornado had detected the presence of, and subsequently locked onto, your hostile radar equipment and automatically sent a jamming signal back to it. Furthermore, an air-to-ground missile aboard the fully-armed aircraft had also automatically locked onto your equipment. Fortunately the pilot flying the Tornado recognized the situation for what it was, quickly responded to the missile systems alert status, and was able to override the automated defence system before the missile was launched and your hostile radar installation was destroyed. Good Day"


Snopes is sceptical about this, but frankly I don't care. No need to spoil a good story with facts, after all.

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Re: What-If 0087: "Enforced by Radar"

Postby thornley » Tue Mar 11, 2014 1:19 pm UTC

Footnote 1 says that, to get the energy needed, you multiply the speed times mc^2 where m is the vehicle mass, and the result is expressed in joules, a unit of energy.

When I try, I get units of kg m^3 s^-3, while a joule is kg m^2 s^-2. The dimensional analysis just doesn't work here; if I switched to the cgs system, for example, I'd come up with a smaller number (presumably of ergs) than I'd get using the normal conversion factor from joules, by two orders of magnitude.

What is the correct formula?

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Re: What-If 0087: "Enforced by Radar"

Postby Exüberance » Tue Mar 11, 2014 1:34 pm UTC

thornley wrote:Footnote 1 says that, to get the energy needed, you multiply the speed times mc^2 where m is the vehicle mass, and the result is expressed in joules, a unit of energy.

When I try, I get units of kg m^3 s^-3, while a joule is kg m^2 s^-2. The dimensional analysis just doesn't work here; if I switched to the cgs system, for example, I'd come up with a smaller number (presumably of ergs) than I'd get using the normal conversion factor from joules, by two orders of magnitude.

What is the correct formula?


I'm pretty sure it's supposed to be E = mcΔv where m is the mass of the car, Δv is the change in velocity of the car, and c is the speed of light

My reasoning:
E = mc2, so the effective mass of a photon/series of photons with energy E would be E/c2.
Since the radiation obviously moves at the speed of light, it's momentum would be E/c.
We want to slow the car by speed Δv, so we want to change it's momentum by mΔv
Assuming the photons are absorbed by the car and don't alter its mass, then E/c = mΔv, so E = mcΔv
If the photons are instead complete reflected (bounce back off the car), then they only need to have half that energy)

I might be wrong though


If we use his example of a 1 (metric) ton car being slowed by 9m/s (~20mph), then the required energy is 2.7 × 1012 J. (2.7 trillion Joules) if the photons are absorbed or 1.35 trillion Joules if reflected. If we assume half the photons are absorbed and half are reflected, we get Randall's result of ~2 trillion Joules.
Last edited by Exüberance on Tue Mar 11, 2014 1:57 pm UTC, edited 6 times in total.

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Re: What-If 0087: "Enforced by Radar"

Postby cellocgw » Tue Mar 11, 2014 1:36 pm UTC

thornley wrote:Footnote 1 says that, to get the energy needed, you multiply the speed times mc^2 where m is the vehicle mass, and the result is expressed in joules, a unit of energy.

When I try, I get units of kg m^3 s^-3, while a joule is kg m^2 s^-2. The dimensional analysis just doesn't work here; if I switched to the cgs system, for example, I'd come up with a smaller number (presumably of ergs) than I'd get using the normal conversion factor from joules, by two orders of magnitude.

What is the correct formula?


I suspect GLR is having fun with you. The "mc^2" as you (should) know is the equivalent energy of the car if converted entirely into photons. The energy needed to slow the car is easier to calculate if you start with momentum conservation :D (maybe). Calculate the momentum of each radar photon, pretend you've got 100% reflectivity to maximize the momentum transfer, and calculate the delta momentum of the car: m*(v1-v2) . Once you know how many photons are needed, you know the energy required.


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Re: What-If 0087: "Enforced by Radar"

Postby Klear » Tue Mar 11, 2014 1:41 pm UTC

cellocgw wrote:Side Note: dunno about "worst scanned PDF ever" but it's sure "slowest downloading link since the days of 24k modems"


Hmm.. I don't have any trouble accessing it. If anyone is having troubles, here's the front page:

http://i.imgur.com/7pJe8lv.png

The rest is surprisingly readable though.

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Re: What-If 0087: "Enforced by Radar"

Postby Thorbard9 » Tue Mar 11, 2014 2:37 pm UTC

Image

I have always thought that my town should use signs like this during the annual seafront air show. When accompanied by military aircraft overhead I think the effect would be greatly enhanced.

Of course, with the population of the town doubling overnight, the chances of anyone breaking a speed limit at that point in the summer is pretty slim.

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Re: What-If 0087: "Enforced by Radar"

Postby BrianK » Tue Mar 11, 2014 2:40 pm UTC

Wouldn't it be much easier to embed electromagnets in the road and induce eddy currents in the speeding cars?

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Re: What-If 0087: "Enforced by Radar"

Postby forward4 » Tue Mar 11, 2014 4:10 pm UTC

Klear wrote:Enforced by Radar

Spoiler:
Image


I'm imagining that the sign guy is actually BHG without his iconic hat.

It's Beret Guy for me.
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Re: What-If 0087: "Enforced by Radar"

Postby eran_rathan » Tue Mar 11, 2014 4:35 pm UTC

forward4 wrote:
Klear wrote:Enforced by Radar

Spoiler:
Image


I'm imagining that the sign guy is actually BHG without his iconic hat.

It's Beret Guy for me.


I have to agree - BHG would not bother with the sign, he'd have the trillion-watt radar gun set at a reasonable distance to watch the fireworks.
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Re: What-If 0087: "Enforced by Radar"

Postby Whizbang » Tue Mar 11, 2014 4:48 pm UTC

He's more devious than maniacal. Just setting up an energy weapon and then blasting a bunch of people isn't his style. He'd set it up in such a way that it was the people's own stupidity that led to getting fried.

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Re: What-If 0087: "Enforced by Radar"

Postby Jackpot777 » Tue Mar 11, 2014 5:16 pm UTC

Whizbang wrote:He's more devious than maniacal. Just setting up an energy weapon and then blasting a bunch of people isn't his style. He'd set it up in such a way that it was the people's own stupidity that led to getting fried.


Image

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Re: What-If 0087: "Enforced by Radar"

Postby gmalivuk » Tue Mar 11, 2014 6:05 pm UTC

thornley wrote:Footnote 1 says that, to get the energy needed, you multiply the speed times mc^2 where m is the vehicle mass, and the result is expressed in joules, a unit of energy.

When I try, I get units of kg m^3 s^-3, while a joule is kg m^2 s^-2. The dimensional analysis just doesn't work here; if I switched to the cgs system, for example, I'd come up with a smaller number (presumably of ergs) than I'd get using the normal conversion factor from joules, by two orders of magnitude.

What is the correct formula?
Using mph is shoddy as hell, but apart from that the thing to notice is that he's ignoring units and just using numbers. If everything's in a self-consistent system like SI, then we need the fact that for light, E=pc, and for our decelerating car, p=mv. Which suggests E=mvc, missing a factor of c from what Randall claims...

Perhaps he's treating v as a fraction of c, so it needs to be multiplied by c to have the right units? I guess that could be. Treat velocity as a dimensionless fraction of the speed of light, and then multiply that by the mass-energy of the thing?

Edit: Yeah, thinking about it more that's definitely how the math works out. It does have one convenient consequence, though, which is the illustration that if you want to use (absorbed or emitted, not reflected) photons alone to change your velocity by x fraction of c, you need to convert x fraction of your own mass into energy. (If you are perfectly reflecting the photons, you only need half that. Also, this is only an approximation, which works at small fractions of c (such as the 1/10,000,000 you'd be going in a typical car). For the same reason it works equally well for emission and absorption, because ex has a derivative of 1 near x=0, so the exponential effects of the previously discussed rocket equation don't come into it yet, approximately.

Catharsis wrote:If a cellphone exerts a billionth of a Newton, and it takes a trillion cellphones to levitate a snowflake, doesn't that imply a 100 kg snowflake?
A billionth of a Newton total in all directions. So a trillion phones would be radiating 1000N in all directions, but a 1cm2 snowflake 1m away is only getting about 8 millionths of that, or 8 millinewtons. Which is... still a bit overkill, considering it'd be almost enough to lift 1g, or about 1000 times more than exists in a snowflake.
Last edited by gmalivuk on Tue Mar 11, 2014 7:03 pm UTC, edited 1 time in total.
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Re: What-If 0087: "Enforced by Radar"

Postby Mikeski » Tue Mar 11, 2014 8:07 pm UTC

gmalivuk wrote:
Catharsis wrote:If a cellphone exerts a billionth of a Newton, and it takes a trillion cellphones to levitate a snowflake, doesn't that imply a 100 kg snowflake?
A billionth of a Newton total in all directions. So a trillion phones would be radiating 1000N in all directions, but a 1cm2 snowflake 1m away is only getting about 8 millionths of that, or 8 millinewtons. Which is... still a bit overkill, considering it'd be almost enough to lift 1g, or about 1000 times more than exists in a snowflake.

The hard part is folding space to get all of those cell phones under the snowflake. If you just ball them up as though you were going to throw them off the back of your moonbound rocket, most of them won't be radiating much in a direction that will move the snowflake upwards.

chalkie wrote:Snopes is sceptical about this, but frankly I don't care. No need to spoil a good story with facts, after all.

It is hard to believe that you could fly a jet fighter with auto-locking, auto-firing, radar-tracking missiles over any populous first-world country on a training exercise without leveling lots of speed traps, microwave transmitters, cel towers, weather radars, puddle-jumper airports, and many other things. I think Snopes is right to be skeptical. It might work in Wyoming or the Northwest Territories, but Great Britain?

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Re: What-If 0087: "Enforced by Radar"

Postby stickler » Tue Mar 11, 2014 9:41 pm UTC

Radar jamming doesn't even work like that.

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Re: What-If 0087: "Enforced by Radar"

Postby Azkyroth » Tue Mar 11, 2014 10:03 pm UTC

My question is, when do we get "Slow Traffic: Pull Off The Road, Curl Up in A Ball in the Front Seat, and Feel Bad About Yourself - Enforced by Aircraft"?

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Re: What-If 0087: "Enforced by Radar"

Postby speising » Tue Mar 11, 2014 10:24 pm UTC

Klear wrote:
cellocgw wrote:Side Note: dunno about "worst scanned PDF ever" but it's sure "slowest downloading link since the days of 24k modems"


Hmm.. I don't have any trouble accessing it. If anyone is having troubles, here's the front page:

http://i.imgur.com/7pJe8lv.png

The rest is surprisingly readable though.


yeah, i not only know worse, i even have to ocr them regularly...

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Re: What-If 0087: "Enforced by Radar"

Postby keithl » Wed Mar 12, 2014 4:39 am UTC

1) Ancient Mad magazine: Speed Enforced by Radar. Oscar Radar, Sheriff.

2) Large parabolic radar dish, dropping off its mount, landing on car, crushing it.

2a) Or just swivelling and pointing at the speeding car menacingly. This was demonstrated with the Stanford Radio Telescope dish in the 70's. ROTC chose the dish as their objective during a weekend training exercise, crawling "stealthily" up the hill towards the 46 meter dish. The operators saw them, and dropped the elevation on the dish so it pointed at the ROTC cadets. They scattered.

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Re: What-If 0087: "Enforced by Radar"

Postby Djehutynakht » Wed Mar 12, 2014 9:08 am UTC

Klear wrote:
cellocgw wrote:Side Note: dunno about "worst scanned PDF ever" but it's sure "slowest downloading link since the days of 24k modems"


Hmm.. I don't have any trouble accessing it. If anyone is having troubles, here's the front page:

http://i.imgur.com/7pJe8lv.png

The rest is surprisingly readable though.




It's not that bad. Old documents tend to make for sucky PDF scans in general... front pages are always bad because they're the outside and get screwed with.

If anyone ever combs the CIA's public document releases on their website, you'll see comparable examples. Admittedly, the CIA screws with their documents a lot more before release (all that black-out...)

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Re: What-If 0087: "Enforced by Radar"

Postby PM 2Ring » Wed Mar 12, 2014 10:41 am UTC

FWIW, footnote 1 now uses the correct formula: E=pc.

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Re: What-If 0087: "Enforced by Radar"

Postby obfpen » Wed Mar 12, 2014 10:51 am UTC

Mikeski wrote:
chalkie wrote:Snopes is sceptical about this, but frankly I don't care. No need to spoil a good story with facts, after all.

It is hard to believe that you could fly a jet fighter with auto-locking, auto-firing, radar-tracking missiles over any populous first-world country on a training exercise without leveling lots of speed traps, microwave transmitters, cel[l] towers, weather radars, puddle-jumper airports, and many other things. I think Snopes is right to be skeptical. It might work in Wyoming or the Northwest Territories, but Great Britain?

The problem here - aside from associating Britain (especially 80s/90s Scotland*) with that "populous first-world country" stuff - is assuming that jet fighters make a habit of flying over populated areas on exercises. Being a not-overly-large island, it's quite easy to reach the sea, which is where the plane was described in the story:
http://www.snopes.com/horrors/techno/radar.asp wrote:The radar had in fact latched on to a NATO Tornado aircraft in the North Sea

I don't think the story as told is true, but it does at least get some details right (e.g. the "A1 [...] between Oldhamstocks and Grantshouse" does look out to sea if you're facing the "Edinburgh to London" traffic, Sir William Sutherland was the Chief Constable of the Lothian & Borders Police) which makes it better than the armchair 'debunking'. (I'm not going to claim the conclusion is wrong, but the argument could be better.) My favourite part is:
Thus, the Tornado in question was most likely [emphasis mine] being "painted" by multiple radar stations at various airports around the UK, and possibly also from the continent. A puny police traffic-enforcement radar signal wouldn’t even be noticed in all the noise.
Isn't this like trying to argue that with all the light bouncing around from the sky and trees and things, you wouldn't notice someone shining a puny laser pointer directly at your eyes?

* This is not intended to denigrate Scotland. Outside London, even 21st century England has plenty of sparsely populated areas, and this is truer still for much of Wales and Scotland. And at the time of the story, I doubt mobile phone towers were even a consideration.

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Re: What-If 0087: "Enforced by Radar"

Postby Luminous » Wed Mar 12, 2014 1:30 pm UTC

Of course, you don't need any of those things. If your goal is to slow down the car—rather than to catch speeders—your radar gun doesn't need any power. You can just stand by the side of the road next to a police car holding a fake radar gun.


When I was a young teenager (13 years old ish) this was essentially what my friends and I did to entertain ourselves sometimes. When a few of us slept over at my place, often after an extended AD&D session, we would sneak out late at night and walk to the nearby 4 lane wide main road, where people regularly went over the 80km/hr speed limit. We'd position ourselves in a convenient cluster of trees and bushes, and when a car came by we'd take a shot with my little 110-film camera (sans film). More often than not the flash of light would result in the driver slamming on their brakes as they were caught by the "speed camera". Really a great way to waste some time with friends.

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Re: What-If 0087: "Enforced by Radar"

Postby RobFreundlich » Wed Mar 12, 2014 1:31 pm UTC

Whenever I see one of these signs, I get a picture in my head of a short bespectacled US Army company clerk from the 1950's pointing a loaded teddy bear at my car.

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Re: What-If 0087: "Enforced by Radar"

Postby aquarius » Wed Mar 12, 2014 6:14 pm UTC

Jackpot777 wrote:Go too fast? That's a blastin'.

I was massively disappointed when, after a brief flourishing, all the "your speed is actually X" digital display road signs got taken away because people were using them as a high score board. Until I realised that I liked them precisely because... I was using them as a high score board. Hm.

I'm still impressed with the idea of showing a smiley face or frowny face on a sign dependent on your speed, which has been done in a few places. Clearly the thing to do is add a bunch of other emoticons as Easter eggs dependent on speed, time of day, phase of the moon, car colour, etc, etc. Could be the next big viral game hit. "I got a :P face!"

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Re: What-If 0087: "Enforced by Radar"

Postby gmalivuk » Wed Mar 12, 2014 8:46 pm UTC

obfpen wrote:
Thus, the Tornado in question was most likely [emphasis mine] being "painted" by multiple radar stations at various airports around the UK, and possibly also from the continent. A puny police traffic-enforcement radar signal wouldn’t even be noticed in all the noise.
Isn't this like trying to argue that with all the light bouncing around from the sky and trees and things, you wouldn't notice someone shining a puny laser pointer directly at your eyes?
Not at all, since the article is talking about radar signals in every case. So the correct analogy is to argue that with dozens of other people near and far shining lasers at you, you wouldn't notice someone shining a puny laser pointer directly at your eyes.

This is not intended to denigrate Scotland. Outside London, even 21st century England has plenty of sparsely populated areas, and this is truer still for much of Wales and Scotland. And at the time of the story, I doubt mobile phone towers were even a consideration.
It depends what you're comparing it to. The current population density of Wales puts it a bit above Florida, so it'd be the 8th most densely populated US state (meaning 43 states are less dense). If Scotland was a US state instead of Wales, it would edge in just behind Michigan and be in the 18th spot (33 less dense).

Sure, England is even denser than New Jersey, at more than 1000 per km2, but even without England the UK is pretty dense from an American standpoint. (Mikeski, the one who described Great Britain as a populated first-world country, hails from Minnesota, with a population density of 26 per km2.)
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Re: What-If 0087: "Enforced by Radar"

Postby Mikeski » Thu Mar 13, 2014 1:34 am UTC

obfpen wrote:
Mikeski wrote:It is hard to believe that you could fly a jet fighter with auto-locking, auto-firing, radar-tracking missiles over any populous first-world country on a training exercise without leveling lots of speed traps, microwave transmitters, cel[l] towers, weather radars, puddle-jumper airports, and many other things. I think Snopes is right to be skeptical. It might work in Wyoming or the Northwest Territories, but Great Britain?

The problem here - aside from associating Britain (especially 80s/90s Scotland*) with that "populous first-world country" stuff - is assuming that jet fighters make a habit of flying over populated areas on exercises. Being a not-overly-large island, it's quite easy to reach the sea, which is where the plane was described in the story:
http://www.snopes.com/horrors/techno/radar.asp wrote:The radar had in fact latched on to a NATO Tornado aircraft in the North Sea

A police traffic-radar gun, though, has a range of about a mile. Maybe two miles for a high-quality one.

If the jet was "out to sea", and the cop was able to check its speed on his radar, it wasn't very far out to sea. Certainly close enough to land to pick up (and lock onto, and waste) a whole pile of RF signal generators.

gmalivuk wrote:Sure, England is even denser than New Jersey, at more than 1000 per km2, but even without England the UK is pretty dense from an American standpoint. (Mikeski, the one who described Great Britain as a populated first-world country, hails from Minnesota, with a population density of 26 per km2.)

...and most of us are in the southeast corner of the state, around Minneapolis. I have relatives out in the dark-green areas.

I didn't spell it out too well in my original post, but I picked "Wyoming and NW Territories" as places that are not just very low population, but that have large areas of near-zero population. (Though, checking Verizon's cell coverage map, I should have picked Montana). I don't think you could fly at a significant fraction of Mach 1 over even the most lightly-populated parts of Great Britain without having at least one target for your anti-radar missiles every minute or three. That's a pretty short training mission. Or a lot of time hitting the "don't shoot that" button. :wink:

(Edit: and since I don't know if cell signals get covered as "possibly-hostile radar frequencies", I'm just using cell coverage as a proxy for "where RF sources are". I know the cell coverage was far lighter at the time of the story.)
Last edited by Mikeski on Thu Mar 13, 2014 2:23 am UTC, edited 2 times in total.

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Re: What-If 0087: "Enforced by Radar"

Postby zaphodbeebledoc » Thu Mar 13, 2014 1:56 am UTC

Image

Fixed that for ya!!
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Re: What-If 0087: "Enforced by Radar"

Postby obfpen » Thu Mar 13, 2014 11:37 am UTC

gmalivuk wrote:It depends what you're comparing it to. The current population density of Wales puts it a bit above Florida, so it'd be the 8th most densely populated US state (meaning 43 states are less dense). If Scotland was a US state instead of Wales, it would edge in just behind Michigan and be in the 18th spot (33 less dense). Sure, England is even denser than New Jersey, at more than 1000 per km2, but even without England the UK is pretty dense from an American standpoint. (Mikeski, the one who described Great Britain as a populated first-world country, hails from Minnesota, with a population density of 26 per km2.)

I did actually notice the Minnesota location, and having road-tripped through there (Montana, too) I'm aware that America has large areas unblighted by human residence. But I wasn't trying to start a who's got the sparsest places competition, especially when average population over large areas is irrelevant unless the distribution is uniform (it isn't) or sample coverage is broad (flight paths are distinct). I only wished to point out that the UK is not one large sprawling population centre; flying a manoeuvrable object on the scale of a few metres without passing over populated areas is perfectly possible, especially when bases are coastal and exercises are conducted at sea. And even if we assume radar-busting technologies are present on planes that fly over inhabited countries, we must also consider whether it's continuously active. Ignoring tedious jokes about military intelligence, it seems prudent to me to turn them on only during the exercises, but have them otherwise disengaged, so commuting over random police officers needn't usually be a problem.

gmalivuk wrote:[T]he article is talking about radar signals in every case. So the correct analogy is to argue that with dozens of other people near and far shining lasers at you, you wouldn't notice someone shining a puny laser pointer directly at your eyes.

But are they the same type of radar signals (search, targeting, pulse-doppler, continuous-wave)? The same frequencies?. If the spinny dishes (and Wikipedia) are anything to go by, most of that radar noise is going to be an ever-present, regular series of short, low-activity pulses (that has perhaps already been accounted for and determined to be distant and non-threatening), whereas the radar gun will be a sudden new, nearby, very active source sustained for several seconds. And if I were a military radar detector, that's exactly the kind of detection I'm going to be concerned by. The plane in the story was low flying, which might also have eliminated some of the background 'noise' if that were somehow a problem. I'm going to explicitly reiterate here: I'm not disagreeing with the conclusion, only pointing out a perceived weakness in the argument Snopes presents - which claims signal obscuration by noise without adequately demonstrating overlap of the signals' characteristics - in a clumsily Socratic kind of way.

And this is a "What If" thread, after all, so I'm also wondering (aloud) under what narrow conditions it could be possible. This map of UK military airspace (PDF) shows TB7 passing over (and aligned with) the stretch of road described. At the northern end is RAF Leuchars, which was home to squadrons of Tornados during the 90s. Military planes can detect radar homing systems, which use continuous wave radar as do mobile speed traps.

Ultimately, the story exists even if its events aren't real, and its origin intrigues me. Maybe it was cooked up by a person/people who knew/were coincidental enough to add more accurate details than urban legends need to survive (cf. Ledasha). Or it's an embellished/misunderstood truth, where a local journalist translated 'the plane automatically prepared a missile for launch, which was then cancelled by the pilot' into 'the pilot had to actively prevent the plane from firing a missile all by itself'. And perhaps a speed detector produced an unexpected reading and locked itself into diagnostic mode to prevent legally useless faulty readings, which was then assumed to have been killed by the plane's jamming system. Either way (unlike the previous comparison) it's a story that bears to be repeated occasionally, and I'm glad chalkie did.

Velo Steve
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Re: What-If 0087: "Enforced by Radar"

Postby Velo Steve » Thu Mar 13, 2014 10:34 pm UTC

I can't believe I didn't ask this question. Those signs bug me every time I see them.

Definitely buying the book...

transFaerie
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Re: What-If 0087: "Enforced by Radar"

Postby transFaerie » Fri Mar 14, 2014 3:23 am UTC

I don't know what Randal's talking about, that PDF might look a little smudgy, but it's selectable! I was so surprised.

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PayasYouDraw
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Re: What-If 0087: "Enforced by Radar"

Postby PayasYouDraw » Fri Mar 14, 2014 1:15 pm UTC

chalkie wrote:The last picture reminded me of an old story...

Two British traffic patrol officers from North Berwick were involved in an unusual incident while checking for speeding motorists on the A1 Great North Road. One of the officers used a hand held radar device to check the speed of a vehicle approaching over the crest of a hill, and was surprised when the speed was recorded at over 300 mph. Their radar suddenly stopped working and the officers were not able to reset it.
Just then a deafening roar over the tree tops revealed that the radar had in fact latched on to a NATO Tornado fighter jet which was engaged in low flying exercise over the Border district, approaching from the North Sea.
Back at police headquarters the chief constable fired off a stiff letter of complaint to the RAF Liaison Office. By return came the reply in true laconic RAF style:

"Thank you for your message, which now allows us to complete the file on this incident. You may be interested to know that the tactical computer in the Tornado had detected the presence of, and subsequently locked onto, your hostile radar equipment and automatically sent a jamming signal back to it. Furthermore, an air-to-ground missile aboard the fully-armed aircraft had also automatically locked onto your equipment. Fortunately the pilot flying the Tornado recognized the situation for what it was, quickly responded to the missile systems alert status, and was able to override the automated defence system before the missile was launched and your hostile radar installation was destroyed. Good Day"


Snopes is sceptical about this, but frankly I don't care. No need to spoil a good story with facts, after all.


There's probably a grain of truth to that. The Tornado's Sky Shadow pod could well have detected the police radar and emmited a signal to confuse it. The police radar gun could have shut down through getting confused about the signals it was now receiving.

Now it's unlikely that a Tornado would have been armed on exercises. I would assume the ALARM anti-radiation missile would be the weapon in question. It's the only weapon in the RAF's inventory that homes in on radar signals. I doubt it would or even could be set to automatic in the way described by the story, though automatic lock on to unexpected threats is very likely, because seconds saved can mean lives saved. However, the response sounds very likely, because that is the RAF (and British Armed Forces in general) sense of humour.
Ah-ooooh! Rolling back the rivers in Time!

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Re: What-If 0087: "Enforced by Radar"

Postby Jamaican Castle » Sat Mar 15, 2014 8:38 am UTC

PayasYouDraw wrote:There's probably a grain of truth to that. The Tornado's Sky Shadow pod could well have detected the police radar and emmited a signal to confuse it. The police radar gun could have shut down through getting confused about the signals it was now receiving.

Now it's unlikely that a Tornado would have been armed on exercises. I would assume the ALARM anti-radiation missile would be the weapon in question. It's the only weapon in the RAF's inventory that homes in on radar signals. I doubt it would or even could be set to automatic in the way described by the story, though automatic lock on to unexpected threats is very likely, because seconds saved can mean lives saved. However, the response sounds very likely, because that is the RAF (and British Armed Forces in general) sense of humour.


If this did happen at all, my guess is the missile is a later embellishment (although the snippy letters do sound plausible). Automatic fire for an anti-radiation missile is an unlikely feature for several reasons: one, it's generally considered impolite to shoot off munitions on a modern battlefield without confirming the target first; two, that goes double for anti-radiation missiles, which are godawfully expensive (the ALARM's price isn't disclosed, but the US equivalent, the AGM-88 HARM, costs a quarter of a million dollars per missile); and three, with only a few missiles per aircraft, they don't want to waste any on decoys.

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Re: What-If 0087: "Enforced by Radar"

Postby rmsgrey » Sat Mar 15, 2014 4:54 pm UTC

Jamaican Castle wrote:
PayasYouDraw wrote:There's probably a grain of truth to that. The Tornado's Sky Shadow pod could well have detected the police radar and emmited a signal to confuse it. The police radar gun could have shut down through getting confused about the signals it was now receiving.

Now it's unlikely that a Tornado would have been armed on exercises. I would assume the ALARM anti-radiation missile would be the weapon in question. It's the only weapon in the RAF's inventory that homes in on radar signals. I doubt it would or even could be set to automatic in the way described by the story, though automatic lock on to unexpected threats is very likely, because seconds saved can mean lives saved. However, the response sounds very likely, because that is the RAF (and British Armed Forces in general) sense of humour.


If this did happen at all, my guess is the missile is a later embellishment (although the snippy letters do sound plausible). Automatic fire for an anti-radiation missile is an unlikely feature for several reasons: one, it's generally considered impolite to shoot off munitions on a modern battlefield without confirming the target first; two, that goes double for anti-radiation missiles, which are godawfully expensive (the ALARM's price isn't disclosed, but the US equivalent, the AGM-88 HARM, costs a quarter of a million dollars per missile); and three, with only a few missiles per aircraft, they don't want to waste any on decoys.


It depends on the setting - on a routine training flight in friendly territory, you'd rather not waste missiles (and civilians) on misunderstandings. If you're overflying hostile territory, you'd probably rather "waste" a missile against a decoy than wait to find out whether you've just been locked up by a SAM launcher...

Leo 1221
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Re: What-If 0087: "Enforced by Radar"

Postby Leo 1221 » Sat Mar 15, 2014 5:25 pm UTC

Is anyone else worried that the sign listing the items that the officer has says nothing about clothing other than the hat?

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Re: What-If 0087: "Enforced by Radar"

Postby Mikeski » Sat Mar 15, 2014 6:26 pm UTC

rmsgrey wrote:
Jamaican Castle wrote:Automatic fire for an anti-radiation missile is an unlikely feature for several reasons: one, it's generally considered impolite to shoot off munitions on a modern battlefield without confirming the target first; two, that goes double for anti-radiation missiles, which are godawfully expensive (the ALARM's price isn't disclosed, but the US equivalent, the AGM-88 HARM, costs a quarter of a million dollars per missile); and three, with only a few missiles per aircraft, they don't want to waste any on decoys.

If you're overflying hostile territory, you'd probably rather "waste" a missile against a decoy than wait to find out whether you've just been locked up by a SAM launcher...

Yes, "wasting" a six-figure missile to defend a seven- or eight-figure jet and its priceless (until the actuaries get involved) pilot seems a fair trade.

(And that's before considering second-order costs, like scattering bits of our classified technology across enemy-controlled ground.)

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ShuRugal
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Re: What-If 0087: "Enforced by Radar"

Postby ShuRugal » Mon Mar 17, 2014 12:38 am UTC

obfpen wrote:And this is a "What If" thread, after all, so I'm also wondering (aloud) under what narrow conditions it could be possible. This map of UK military airspace (PDF) shows TB7 passing over (and aligned with) the stretch of road described. At the northern end is RAF Leuchars, which was home to squadrons of Tornados during the 90s. Military planes can detect radar homing systems, which use continuous wave radar as do mobile speed traps.



the biggest problem with this is that it still ignores one very important factor: scale.

I am not familiar with the related UK regulatory authority, but here in the States, the FCC's Part 15 limits the transmission power of non-licensed equipment to a maximum output of ten watts, and that particular limit is in the frequency band reserved for equipment to locate buried cables. The maximum output for unlicensed equipment in the microwave range (which is where radar operates) is limited to a field strength of (in the highest instance in the list, field disturbance detectors) to .5 volts/meter measured at a range of 3 meters. While I am not conversant with UK and EU regulations, I would be shocked to find that they allowed significantly more powerful equipment to be operated without licensed operators.

Military radar transmitters, on the other hand, measures their power output in megawatts for ground based units, and kilowatts for airborne systems.
Even if, by some freak chance, the police radar gun was outputting on a frequency and function which would be interpreted as a tracking signal by a Tornado's passive detection gear, that gear wouldn't even know the thing was there, and certainly would not have enough signal strength to lock on to source, unless the aircraft was in imminent danger of crashing into the policeman and his speedtrap.

The correct analogy here is not strobes vs lasers, it's laser strobes vs a static discharge collimated by means of two pairs of reading glasses.



rmsgrey wrote: If you're overflying hostile territory, you'd probably rather "waste" a missile against a decoy than wait to find out whether you've just been locked up by a SAM launcher...


considering that anti-radiation missiles such as the HARM are stand-off offensive weapons designed to eliminated hostile radar emitters from outside of enemy AD range, if you're overyflying hostile territory with any quantity of them still on your rails, you're doing something seriously wrong.


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