What-If 0087: "Enforced by Radar"

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

Postby PayasYouDraw » Mon Mar 17, 2014 3:18 pm UTC

ShuRugal wrote:
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.


Perhaps if there is a grain of truth to it it would be the SkyShadow pod putting out an active signal which could have confused the radar gun into shutting down without actually detecting it.


ShuRugal wrote: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.


Part of the SEAD mission is to react to radar detection. The ALARM does have a 100 km range, but it is equally suited to taking out SAM radars that are activated when the aircraft is much closer. Those missions often require hunting for enemy radars, which means getting close enough to wake them up to your presence. Clever SAM operators only switch their radars on when the target is visible.

Tornado's carry 2 or 3 ALARMs on that mission, and no other offensive weapon because they don't have enough capacity to do so.
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Re: What-If 0087: "Enforced by Radar"

Postby ShuRugal » Tue Mar 18, 2014 3:36 am UTC

PayasYouDraw wrote:Perhaps if there is a grain of truth to it it would be the SkyShadow pod putting out an active signal which could have confused the radar gun into shutting down without actually detecting it.


that's reasonable. At close enough range, an ECM pod broadcasting a general CW confusion program could induce the police radar to shut itself off due to inability to interpret erroneous readings. I would expect the MFR to have it display an error code instead of total shutdown, but that is entirely variable on the design end, and so this is still a credible possibility.

Part of the SEAD mission is to react to radar detection. The ALARM does have a 100 km range, but it is equally suited to taking out SAM radars that are activated when the aircraft is much closer. Those missions often require hunting for enemy radars, which means getting close enough to wake them up to your presence. Clever SAM operators only switch their radars on when the target is visible.

Tornado's carry 2 or 3 ALARMs on that mission, and no other offensive weapon because they don't have enough capacity to do so.



SEAD is a horrifically complicated mission profile, for exactly the reason you describe. Enemy EW radar tracks inbound AC and hands them off to individual SAM installations, who then crank up their own tracking radars when the flight is in range for a good probability of kill. Conversely, the SEAD flight will try to determine probable placement of individual launch sites based on known EW stations, local terrain, available intel, and even confirmed launches. It then devolves into a game of high-stakes chicken. A modern SEAD package would, ideally, even include an AWACS unit loitering outside SAM range to identify enemy emissions, plot their locations, and determine the threat they represent.

The point is, a pilot tasked with SEAD should already have a good general idea of where the threat will be coming from, where safe fly zones are, etc etc. There would be no question of deciding on wasting a missile on a 'decoy' radar site because it surprised him. If a SEAD flight finds itself under surprise attack by enemy air defenses, someone is doing their job wrong.

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

Postby keithl » Tue Mar 18, 2014 4:02 pm UTC

In the American West, roads are long and cities are far apart, so it was common in the age of expensive plane tickets and cheap fuel to drive much faster than the speed limit, and use radar detectors to slow down for speed traps. Now the "speeding ticket" occurs at the gas pump.

My crazy friend Oz had fun with radar detectors - he built radar emitters. He would follow fast cars down the interstate at night, and turn on the emitter, watching drivers brake suddenly. He called this "trolling for taillights".

Oz later made a product with his emitters, incorporating them into yellow flashing lights for construction barricades. Those caused many speeders to slow down around construction sites, saving worker lives without the expense of 24x7 cops.

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

Postby eran_rathan » Mon Mar 24, 2014 5:11 pm UTC

keithl wrote:In the American West, roads are long and cities are far apart, so it was common in the age of expensive plane tickets and cheap fuel to drive much faster than the speed limit, and use radar detectors to slow down for speed traps. Now the "speeding ticket" occurs at the gas pump.

My crazy friend Oz had fun with radar detectors - he built radar emitters. He would follow fast cars down the interstate at night, and turn on the emitter, watching drivers brake suddenly. He called this "trolling for taillights".

Oz later made a product with his emitters, incorporating them into yellow flashing lights for construction barricades. Those caused many speeders to slow down around construction sites, saving worker lives without the expense of 24x7 cops.



that's rather brilliant. Where can one purchase said emitters?
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Re: What-If 0087: "Enforced by Radar"

Postby Mikeski » Mon Mar 24, 2014 6:07 pm UTC

eran_rathan wrote:that's rather brilliant. Where can one purchase said emitters?

Just for this purpose? Legally? Nowhere (in the US, anyway). The FCC says who gets to use what part of the spectrum. "Random schmuck" and "the part where radar is" isn't one of the legal combos. You can't buy radar jammers, which is what these would be.

That said, I know a ham-radio operator who claims he can tune his in-van radio to broadcast at or near-enough-to one of the radar bands to trigger radar detectors. He does the reverse of the previous post... flips it on when some leadfoot is chasing him. Speed demon approaches, catches signal, drops back for a few miles... takes off again, catches signal again, backs off again...

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

Postby Kaiman » Fri Apr 11, 2014 10:29 pm UTC

If you want to slow down a one-ton car by radiation pressure, your radar gun would need to deliver about two trillion joules worth of radiation—the energy of a small nuclear weapon.


This doesn't seem right. The energy required to slow an object at a given mass & velocity is not dependent on the source of the energy. So this would mean that you are applying the energy of a nuclear weapon to your vehicle whenever you brake?

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

Postby gmalivuk » Fri Apr 11, 2014 10:38 pm UTC

To slow down you want to apply momentum, and the momentum of radiation pressure is a lot less energy-efficient than the momentum of slower-moving things like cars.
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Re: What-If 0087: "Enforced by Radar"

Postby JonasRahbek » Tue Dec 02, 2014 10:51 am UTC

With chance of being repetitive..

Doesn't it just take a singe Radar gun???
The question goes: How intense would radio waves have to be to stop a car from going over the speed limit

If you imagine a car going en infinitesimal amount over the speed limit, lets say 55.0000000000000001 mph. the margin down to the speed limit would definitely be conquered by the Radar....

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

Postby PinkShinyRose » Thu Dec 18, 2014 12:15 am UTC

keithl wrote:In the American West, roads are long and cities are far apart, so it was common in the age of expensive plane tickets and cheap fuel to drive much faster than the speed limit, and use radar detectors to slow down for speed traps. Now the "speeding ticket" occurs at the gas pump.

My crazy friend Oz had fun with radar detectors - he built radar emitters. He would follow fast cars down the interstate at night, and turn on the emitter, watching drivers brake suddenly. He called this "trolling for taillights".

Oz later made a product with his emitters, incorporating them into yellow flashing lights for construction barricades. Those caused many speeders to slow down around construction sites, saving worker lives without the expense of 24x7 cops.

I don't know whether petrol prices are really related to speeding. In the Netherlands petrol prices are also high, distances are short, yet the government makes plenty of money on speeding tickets. They even have two-camera systems that calculate your average speed over a distance with signs warning for them and still seem to get back their investment.

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

Postby DanD » Tue Dec 23, 2014 9:48 pm UTC

Mikeski wrote:
eran_rathan wrote:that's rather brilliant. Where can one purchase said emitters?

Just for this purpose? Legally? Nowhere (in the US, anyway). The FCC says who gets to use what part of the spectrum. "Random schmuck" and "the part where radar is" isn't one of the legal combos. You can't buy radar jammers, which is what these would be.

That said, I know a ham-radio operator who claims he can tune his in-van radio to broadcast at or near-enough-to one of the radar bands to trigger radar detectors. He does the reverse of the previous post... flips it on when some leadfoot is chasing him. Speed demon approaches, catches signal, drops back for a few miles... takes off again, catches signal again, backs off again...


The claim is completely reasonable. The 1.2 centimeter band (24-24.25 GHz) is licensed for amateur radio and is a portion of the K-band (18-27 GHz), a portion of which is used for police speed radars. In theory the specific sub-bands don't overlap much, but I suspect the frequency discrimination on radar detectors isn't that great.

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

Postby DanD » Mon Apr 18, 2016 10:10 pm UTC

ShuRugal wrote:
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.


And your last bit shows the problem with your first bit. The entire point of the radar detection capability in an anti-radiation missile (even more so in an ECM pod) is to detect the source of the radiation from far outside the detection range of the emitter. Ideally far enough outside that you can detect it, localize it, identify it, lock on it, fire on it, and have the missile reach and destroy the target, all before the the launcher detects you and can fire. All while you are travelling towards it at 2400 kph.

The SA-11 has a detection range of 85km. Not my area of expertise, but at 3km every 2 seconds, even 5-10 seconds of extra detection range is going to seriously attenuate that. Especially if you're talking about the relatively weaker continuous engagement radar rather than the stronger tracking radar.

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

Postby ShuRugal » Thu Apr 21, 2016 1:25 am UTC

DanD wrote:And your last bit shows the problem with your first bit. The entire point of the radar detection capability in an anti-radiation missile (even more so in an ECM pod) is to detect the source of the radiation from far outside the detection range of the emitter. Ideally far enough outside that you can detect it, localize it, identify it, lock on it, fire on it, and have the missile reach and destroy the target, all before the the launcher detects you and can fire. All while you are travelling towards it at 2400 kph.




Right, the bit that you are missing here is that the launching aircraft (LA) only needs to be travelling straight at the target radar set at the moment of launch. On approach, the LA can approach the target at as much of an oblique angle as the sensor is able to slew and make detection, greatly reducing closure rate. Once the target is locked and the LA is ready to fire, pilot begins to turn as hard as possible without bleeding airspeed towards the target, launches when good, and then either turns to the next target or tightens up his turn and begins to egress. Verification of target destruction is carried out by supporting elements (overwatch aircraft, FAC, JTAC, etc)


The SA-11 has a detection range of 85km. Not my area of expertise, but at 3km every 2 seconds, even 5-10 seconds of extra detection range is going to seriously attenuate that. Especially if you're talking about the relatively weaker continuous engagement radar rather than the stronger tracking radar.


The point you're missing here is exactly how massive the scale of difference between power levels actually is. A hand-held radar gun might have an output power of, at the extreme end, 6 watts (and even this would be in gross violation of FCC regulation). on the other hand, the AN/SPY-1 (Aegis Radar) has an output of 6 million watts.

Another important thing to know is that radio signal strength drops off in accordance to the inverse-square law with difference. Under ideal conditions, doubling the power output increases the signal range by 50%. Since the output of the Aegis is 1-million times the power of our hypothetical over-powered police radar, the signal can be received approximately 500,000 times as far away at the same strength.

The AN/SPY-1 has a published detection range of 100 miles. To estimate how far away it could be detected, we take into account that the detection range of a radar set is subject the the inverse square law... twice (once for the signal to the target, and again from the reflection back to the radar). General rule of thumb is that a radar signal can be detected at 4x the range it can detect a target. This gives us 400 miles detection range of the AN/SPY-1 by our SEAD flight. Adjust for the fact that the flight has a much smaller dish than the emitting radar, and say 300 miles.

Now, 1/500,000th of 300 miles... is 38 inches.

Basically, the only way that tornado could detect a police radar is by crashing into it.


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