I have always assumed that the enemy radar has stopped searching, with occasional pings, and has begun pinging you continuously. Right or wrong, or is it just a movie thing?
You may be mixing radar with sonar. Radar is exactly like shining a light on something, except using radio frequencies. Crudely, if the light stays on you, they’ve locked on to you. Modern radar equipment can do rather better than that.
From this, it sounds like that’s the way older systems worked.
But things are much more sophisticated now:
[Moderating]
I don’t see an arts discussion here. It looks factual, so I’m bumping it over to General Questions.
EDIT:
Er, that is, I will as soon as I figure out how moving threads works nowadays. Is this it?
Yes.
In very general terms, an air defense system will have search radars that scan a large area. Any positive returns are then interrogated to see if they (the return) are friend or foe (IFF). An incorrect response or non-response will trigger an alert (possible intercept - other factors come into play). A target illumination radar will attempt to “lock on” the target. The illumination radar has a much narrower beam and takes its cue from the search radar on where to look. A “lock on” means an anti-aircraft missile may be on the way shortly. The target will see a search radar signal as a number of individual sweeps while the targeting radar will be constant illumination.
There’s all kinds of variations (pulse, frequency hopping, etc…) but having someone “lock on” to you is bad. You’ll need countermeasures, evasive action, sweat and tears in that situation.
A “Lock on” is when a radar transitions from search mode to targeting mode. As in Reimann’s first cite, in general that involves the radar paying a lot more attention to that specific target and relatively less attention to the rest of the search space. Historically, like pre 1990ish, these changes in radar emission could in principle be detected by the target aircraft / ship / whatever and displayed to the crew.
Reimann’s second link is about sophisticated warning receivers and is not so much about the latest and greatest radars.
As the electronics have gotten fancier this whole scenario gets more complicated than the classical 1950s-1980s case outlined above. Right now the pendulum has swung a long way towards the offense and away from the defense.
Modern radars can detect targets using much less emitted power than before. Which means the warning receivers need to be even more sensitive to even recognize search, much less track, signatures. As well, modern 2010 radars can emit across a wide frequency range such that older warning receivers never recognize the incoming signals as hostile radar.
Modern 2010+ radars are also much more able to track multiple targets without altering their output. The end result is that being searched for, being found, and being tracked all look exactly the same to the target. Under those circumstances, even in principle it’s become impossible to say “They’ve locked onto us.” From the target’s POV there’s no way to tell.
Another handy invention of the 1990s and later is the IRSTS (InfraRed Search and Track System). These have been around in cruddy form since the 1970s but really came into their own in the 1990s. With IRSTS (or equivalently imaging visible-spectrum TV sensors), the radar can detect a target is generally over that way, and signal the IRSTS to look over there, all without tipping its hand by going into a tracking mode.
If IRSTS detects a target signature in that direction it can begin to track it left/right & up/down. The radar can then look someplace else. The target has no way to know a TV/IR sensor is watching it. Just as you have no way to know whether somebody is looking at you from across a crowded room. Eyes don’t emit beams you could detect. The TV/IR sensor can keep a track through a lot of maneuvers and although it has no way to directly compute range to the target it can track relative bearing. Which may be enough info to press the attack or even to launch weapons.
Finally, traditionally in pre-1990s radars when a radar-guided missile was launched, the radar would switch mode from target tracking mode to target tracking plus missile guidance mode. That transition was readily detectable by the target. Who’s warning system would signal “Red Alert; inbound missile on the way!!”
IR missiles can be locked on and fired with no such emissions, and no warning to the target. Modern radar guided missiles use lots of fancy tricks to avoid being so obvious. Including things like the targeting radar computing where in the space the missile is likely to meet the target, then telling the missile to fly to those GPS coordinates followed by launching the missile. The aircraft radar then looks someplace else while the missile is in flight. The missile wakes up its own onboard radar a handful of seconds before arriving at that GPS point in space, starts looking around, and kills the closest thing it finds. Long before the target can react to the surprise attack.
The latest and greatest thing is networked warfare. All the aircraft or ships are hooked together by stealthy datalinks and each can see and understand the combined picture revealed by everybody’s sensors: radar, IR, TV, acoustic, passive RF receivers, laser, live satellite video, etc.
And anybody can shoot at any target identified by the complete fused sensor picture. Plus it can all be deconflicted so three shooters don’t all choose the same bad guy to hit first.
This affords the idea that the shooters may never have to emit at all; they just passively consume the state of the battle area sent over the network from other sensor systems on other platforms.
Once that happens, there’s not necessarily any way even in principle for the target(s) to know they’ve been recognized or prioritized for attack. If you can get the weapons themselves into the network, they too can be silent up to impact.
The future is fast becoming very lethal. Very expensive, but very, very lethal.
So the junior jackboots close with velcro instead of laces; whodathunkit. 
Radar actually does ping. The radar transmitter will send out pulses and will then listen for the echo. The time from the transmitted pulse to the receive pulse tells you the distance and the frequency shift tells you the target’s speed.
Continuous wave radars have existed (and are still used). Those do basically “shine” the radar beam at the target continuously, like a beam of light. CW radars have the advantage of being cheap and reliable. One disadvantage of CW radars is that they don’t give you range unless you modulate the signal, which kinda turns it into a pulse-ish type of radar.
Back when I worked on radar systems (early 1990s), your typical fighter jet radar had a moving antenna and sent out fairly high power pulses at specific frequencies. When the radar locked onto a target, it would predict where the target was likely to be next and wouldn’t search such a wide area. This meant that from the target’s point of view, the pulses would get a lot more frequent. It wasn’t that the radar was sending out more pulses, just that the pulses were no longer spread out across the larger search pattern.
These days, your typical fighter jet radar uses synthetic aperture radar (SAR) which uses a phased array of antenna elements to electronically steer the radar beam instead of moving the antenna.
SAR type radar units can steer the beam around faster and, since they don’t have a moving antenna, they are much more rugged and reliable.
They’ve also switched to spread spectrum pulsing, so the radar no longer sends out high powered pulses but instead spreads out the pulses over a very wide range of frequencies. From the target’s point of view, the radar pulses are spread out so much that the radio energy just looks like background noise. The pulses aren’t concentrated in narrow frequency bands so they can’t be as easily detected.
The older single-frequency pulse-doppler radars definitely “pinged”. They sent out single-frequency pulses. Spread-spectrum radars still pulse, but they send out a wide spectrum of tiny pulses. I guess you can still call that a “ping”. If you want the audio frequency equivalent, the older radars basically yelled eee eee eee eee eee and the spread spectrum ones very quietly say shh shh shh shh shh.
Waitasec. I checked the date. **Chronos ** mods… Did I miss the memo? (I havent looked into ATMB for a while.) Once a mod, always one?
@Leo
Go check ATMB. All will be explained.
What actual or potential defenses seem like they’ll be fairly effective? Decoys, dodging, outranging/outrunning, staying below the horizon, shaping/RAM, anything else?
Are the various types of jammers still much use against somewhat sophisticated enemies?
Clearly stealth is the main defensive gain recently (~20 years). How much longer it’ll last is an open question.
Outranging works fine as long as you don’t need to go where the defenses are defending. That’s pretty hopeless. OTOH, for any given level of tech, it’s easier to make a sneaky/stealthy missile than it is an aircraft. Due to size of nothing else. So progress in missile motor efficiency will improve stand-off range and launch vehicle survivability.
Decoys are expensive and large. So few in number. A ship could carry larger decoys than an aircraft, but probably also needs a larger decoy.
Low altitude and terrain masking is very effective against surface-based and low-altitude aerial radars. It was certainly the tactic of choice in my era. The advent of high altitude platforms with good look-down capability took a lot of that sanctuary away. As did operations over a populace seeded with scattered MANPADs.
My personal view is detection is on an inexorable rise. Hiding aircraft and surface ships from well-equipped enemies will soon be close to impossible.
So we’ll move on to speed. Even if you can detect a Mach 8 incoming missile there isn’t time to do anything about it. Directed energy weapons are another option which will alter the balance between offense and defense.
Finally, it’ll still be the case that ordinary aircraft and ships are undetectable by folks with only simple defenses. So to decide where and how to invest in capabilities we first need to know whether we’re going to fight the PLA or the Taliban or Latin American drug smugglers. Answering “all the above” is a defense contractor’s dream.
Both of those would suggest that munitions will travel at quite high altitude, correct? Ramjet at 30-40km altitude? Scramjets when/if they can fly without blowing up?
The radar horizon for a platform at 10KM altitude against a 0km* altitude target is about 400km. Against a 15km** altitude target, it’s 900km. Is that realistic against non-stealthy targets?
Seems like AEW and EW planes will become akin to the capital ships of the past.
- Like a ship or a sneaky plane
** Like a fighter or early warning plane
How does AEW or GCI with datalinks work in this future? From what I have read the datalinks can make even older airframes potent in the Air Defence role. The Indian AF had hoped to keep its MiG-23’s in longer with the A-50 inductment, though the lousy state of the airframes might preclude that.
What’s interesting to me is how little the Russians have bet on stealth. Partly due to their economic climate, but even them most roubles have gone to none stealth platforms and ECM (I believe they have come up with some really advanced kit recently). From the open sources that I have read, the Russians seem to think that stealth brings with it unacceptable performance penalties in range and payload, as well as mission flexibility. Its quite telling that except for the Sukhoi T-50, most new Russian aircraft like the Su-34 Fighter bomber and the various new Su-30 and MiG-29 versions are not stealth, ratehr rely on powerful ECM.
The Chinese have the money to go for both, but even with the J-20, they have inducted the J16, non stealthy, for strike missions
AEW/GCI could function much as it traditionally does. The AEW platform can see farther than can the fighters. If we posit that any fighters that are forward can datalink their sensor info back to the AEW platform then its field of view becomes enlarged in the direction the fighters are moving. IOW it gets longer- and longer-ranged exactly in the areas of greatest tactical interest. Win-win.
The GCI function can datalink target designations and attack approvals back more quickly and accurately than traditional verbal vectoring and commands.
As well, multi-fighter flights can coordinate internally via datalink assisted by automatic target prioritization. In my era that all had to be done by voice by the fighter flight leader. It was difficult for 2, or worse 4, fighter pilots to verbally explain to each other what their radars were seeing, then have lead decide who was going to shoot whom when. We saw that a lot when practicing against our own F-15s. They’d still be coordinating their radar missile attack plan when we arrived in the middle of their formation with multiple Sidewinders already in flight. 
Doing all that by computer would improve their odds of a successful attack with no untargeted leakers.
Stealth: The Russians are a bit of a special case as their military R&D took a 20-year holiday after the SU collapsed and they were just getting it ramped up again when their economy hit the skids. So I attribute their relative lack of stealth development to mostly that, coupled with a doctrine that simple, rugged, and badly maintained but bought in high quantity has a quality all its own.
The other possibility is that the Russians were well along with VHF radars when the US went public on the F-117. Pretty quickly they discovered they could track it just fine. At which point they put almost all their eggs in the cheap counter-stealth radar basket, not the very expensive stealth aircraft basket. Betting against Russian RF tech is a bad idea; that stuff is pure voodoo and they’re magicians with it. OTOH, as everything moves into the digital domain software skills begin to predominate over the voodoo. I’m unclear who’s got the lead there. Especially when you consider Google pays about 5x what Raytheon does for top tier talent.
As you say, the Chinese have a leg in each camp. They get some tech transfer from Russia, and steal plenty more from us. Plus their own indigenous R&D which is good and getting better. And they can afford to pursue both options simultaneously.
The real problem with stealth so far is the high cost of procurement and the high hourly cost to maintain the stealthy surfaces. It makes traditionally sized force structures unaffordable.
187 F-22s is one of the dumbest things the USAF ever did. IMO if you can’t afford a thousand you can’t afford the first one either. Smaller countries can have smaller force structures that are effective for the missions they have. 187 of anything doesn’t spread far enough to cover US commitments to our various strategic missions. Which is not to say those missions are all well-founded in 2016. But given we think we need to do all of them, 187 isn’t the number that’ll get 'em done.
Their mil R & D is not lacking for funds, the Chinese are more than willing to subsidize them when it suits them.
Do you think the Russian Air Forces opinion of stealth aircraft payload and range penalty (no external fuel tanks or weapons) not being worth the gain in low observability is a valid one?
Thanks, y’all. You carry on while I explain the second stage of a Nike Ajax parked out front of the VFW hall to my daughter.
Amen. Just like today, tomorrow’s air wars will be fought with '70s technology, designed in the '60s. I read once that early F-16s were shod with wheels off mothballed B-58s. True?
The tradeoff of weapons loadout is large. Essentially you’re reduced to carrying small weapons that must be precision-guided.
Conversely, in the e.g. F-16 we specialized in using a smart aircraft to deliver dumb bombs. Which worked well enough in the pre-internet era against our expected near-WWIII scenario. Now that we need to avoid the “blown up wedding trending on youtube” effect it’s become important to have precision guidance and small warheads with reduced collateral damage. Stealth or no.
At least for our side. From what I read of the battle in Syria, Russian tactical aviation is still in the Viet Nam to '80s USAF model of just dumping bombs near or on top of whatever moves and leaving it to Allah to sort the Good from the Bad.
If that’s the Russian attitude to collateral damage then yes, stealth carries a huge and probably unaffordable penalty.
Ultimately though, a fighter or attack aircraft that doesn’t return from one of its first few sorties is tactically useless. You have to deliver ordnance on target this morning *and *survive to fight again this afternoon. If not via stealth, via what?
I don’t have hard numbers now, but back in the day I always thought the SU/WP had vastly more SAM and AAA capability than did the US/NATO. The SU/WP intended to defend its forces from the ground whereas US/NATO intended to do so via air superiority.
As such the Russians may have internalized the idea that pressing into heavily SAM/AAA defended areas just wasn’t that big a problem versus servicing their total target list. We may be seeing now the echoes of that institutional position then. IMO the US / NATO position hasn’t changed much. It’s still mostly running on echoes, not fresh zero-based analysis.