

How does a fighter jet lock onto and keep track of an enemy aircraft? (2013) - KhalilK
http://gizmodo.com/how-fighter-jets-lock-on-and-how-the-targets-know-1644871272

======
reduce
The system has not performed "a lock on the target", at least not in the way
that the language leads you to believe. The tool is making a prediction, that
within a certain level of confidence, and given the present parameters, that
firing the missile will result in the neutralization of the target.

There's growing number of ways, both active and passive, that targets can be
tracked or future positions predicted. One of the answers on that page hints
at this, the other answer is misleading and often not how it's done in many
modern systems.

Source: engineered parts of these systems before.

~~~
berkut
The radar and weapon control systems are "locked on" to from the aircraft's
perspective - I don't really understand what you're talking about...

A particular target has been identified, it is being tracked (maybe at the
expense of scanning for other targets if its an older system, probably with
track-while-scan otherwise), and based on this updates are being sent to the
missile in order to control its initial trajectory when it gets launched to
point it in the correct direction.

------
ufmace
Related anecdote - I worked with a coder a while back who was a naval aviator
before he went back to school, flying carrier-based transports. I asked him
once about whether he would have wanted to fly fighters instead, and he said
that just flying transports was already a huge amount of work, as far as
flight plans, training, practice, and such. Flying fighters apparently
involved doing all of that same work, plus a bunch more for weapons, tactics,
etc, so those guys never had any free time. Apparently, flying fighters wasn't
nearly as fun as it sounds.

~~~
bkohlmann
believe me, flying fighters really is as much fun as it sounds. It is more
work than the transport guys, but you get out what you put in. its all worth
it coming in for a 450 knot overhead at 600', pulling six g's in the break,
then catching the three-wire aboard the carrier.

~~~
swah
To remember that there are people that can and do pilot those jets regularly,
before coming home to their family, gives me a kind of feeling of vertigo and
envy, that my life (and the other peasants around me) is flat, onedimensional,
boring and meaningless.

But soon I forget and resume watching Netflix.

------
IgorPartola
So why don't they include two radars, one for sweeps and one for tracking? I
know, I know, weight, power, etc. At the same time, isn't that the obvious
answer?

~~~
_djo_
No space. Take a look at this image, it's the standard AN/APG-63 on an F-15C
fighter aircraft:
[http://commons.wikimedia.org/wiki/File:APG-63_radar_of_F-15_...](http://commons.wikimedia.org/wiki/File:APG-63_radar_of_F-15_1985.JPEG)

Note how the radar's processing units and dish take up the entirety of the
aircraft's nose and how large the system is compared to the technician working
on it. There simply isn't enough space to add another radar.

Nor would it make sense to split that into two smaller radars, as the size of
the dish and processing units is strongly linked to its power and range.
That's one reason larger aircraft like the F-15, F-14 and Su-27 have longer-
ranged and more powerful radars than smaller fighter aircraft.

This track vs scan limitation is removed by Active Electronically Scanned
Array (AESA) radars such as this AN/APG-63(V)2 retrofitted to a USAF F-15C:
[http://www.pacaf.af.mil/shared/media/photodb/photos/070720-F...](http://www.pacaf.af.mil/shared/media/photodb/photos/070720-F-9999J-001.jpg)

Rather than having a mechanically-slaved reflective dish, an AESA radar has
hundreds of Transmit/Receive Modules (TRMs) each capable of acting like a tiny
radar dish by transmitting or receiving on its own frequency and being steered
its own direction.

So now, rather than having the radar dish jump between track and scan at rapid
intervals, the system can just dedicate a few hundred of the AESA TRMs to
tracking one or more targets while letting the remainder continue sweeping the
skies. There's no limitation on azimuth because each TRM can be individually
steered.

So in short, the answer is that the latest fighter aircraft don't have two
radars, they have hundreds or thousands of tiny radars that can work together
in a whole bunch of useful combinations.

 _Edit: Replaced initial image with a Wiki Commons link that doesn 't have
linking issues._

~~~
theoh
It is important to note that the antennae in a phased array (TRMs) cannot be
"steered" individually: it is the electronics that creates a beam by timing
the transmit and receive signals to a number of antennae. It's similar to the
way an array of atoms creates a pattern of beams in x-ray crystallography, if
that makes it clearer.

~~~
rcxdude
This does also mean that the whole array can be pointed in multiple directions
at once: The only limitation is the number of phase shifters coming off of
each antenna (if the signals are directly sampled and then the beam forming is
done in software you are then only limited by your processing power. I'm not
sure if this is currently possible in radar but I've seen it done for sonar).

------
OldSchool
Hmmm, I was kind of hoping for an explanation of how the control system
determines how to modify the highly directional antenna's orientation to
continue to maximally "illuminate" the target once it's been selected from a
general scan.

Can anyone describe the solution to this?

Example idea: Once selected for "lock," the antenna scans in small circles and
migrates its central point toward the point on the scanned circle that
provides the strongest return, allowing for variation due to noise sources.

~~~
ChuckMcM
There is a book on it[1]. But suffice it to say that the radar is computing an
"exit vector" when the target it moving away from center and applying a
correction to the pointer. I built a similar system with LEDs when building a
tracking system for two moving robots. In my case I used a parabolic dish (a
solar cigarette lighter) and a line of LEDs (bar graph display) as detectors
rather than lights. Since the target robot and the pursuing robot had their
beacon and search dish in the same plane I could reduce the problem to a
managable bit of 2D geometry. As the signal went off axis you could turn the
robot to re-align by applying the opposite rotation.

[1] "Multiple Target Tracking with Radar Applications" \- Sam Blackman
([http://books.google.com/books?id=Ag9TAAAAMAAJ&q=tracking+mul...](http://books.google.com/books?id=Ag9TAAAAMAAJ&q=tracking+multiple+targets+with+radar&dq=tracking+multiple+targets+with+radar&hl=en&sa=X&ei=VVk4VPiNLsnwoAS4rICoCw&ved=0CC0Q6AEwAA))

~~~
OldSchool
Thanks for the thoughtful reply and reference!

------
platz
After playing something like Falcon BMS you'll have all these radars
memorized.
[https://www.youtube.com/watch?v=uU3pmXvnc0k&hd=1](https://www.youtube.com/watch?v=uU3pmXvnc0k&hd=1)

It acutally makes the sim quite fun to play, although you do have to get past
that learning curve. I think for me it was the learning part that was kind of
fun too

~~~
Perseids
The radar discussion in the video is pretty good itself. It begins at 30min
31sec:
[http://youtu.be/uU3pmXvnc0k?t=30m31s](http://youtu.be/uU3pmXvnc0k?t=30m31s) .

------
jlas
Another interesting aspect is the Lock-On detection of the enemy aircraft.
Aircraft are able to identify when they're being tracked by other aircraft or
homing missles. [1]

[http://en.wikipedia.org/wiki/Radar_warning_receiver](http://en.wikipedia.org/wiki/Radar_warning_receiver)

~~~
lucb1e
like mentioned in the answer..?

------
ibisum
Upon reading of RWR and its delights, at least one part of me, the techno-
dweeb, goes "weeeh!" ..

Another part, more of a hippy tree-hugger, goes "wish we were using this to
figure out where to drop the water/medicine/books instead of _BOOMB_ devices"
..

I mean, seriously. Tell us where to drop the books, and _BOOM_ there it is:
how it should be.

~~~
caf
You might be interested in the UAV Challenge:

[http://www.uavoutbackchallenge.com.au/](http://www.uavoutbackchallenge.com.au/)

------
Someone1234
Good response, worth the read. Heck the response alone could justify their own
article.

As an aside: I hate quora' site design so much I have blacklisted it using
Google Personal Blocklist. Somehow I dislike it more than Experts Exchange
(which is also blacklisted), it is just super cluttered with nonsense, rolls
into the comments section without warning and rarely offers good content (see
Experts Exchange again).

That being said Yahoo! Answers also rarely has good content but at least with
Yahoo! Answers you can determine that with a glance. You visit the page and
you can see the answer (or lack of answer). So Yahoo! Answers remains in my
search results, Quora and Expert Exchange have been vanished indefinitely.

PS - Quora also likes to spawn pop ups whenever you click anywhere on the page
for no real reason (just asks for your Quora login details). For someone who
randomly highlights blocks of text while reading this is pure hell...

~~~
click170
I remember you used to see experts exchange or the like come up in search
results and you could block it right there, in your search results without
having to go to a separate page. Since they've hidden it, I honestly thought
they'd removed the ability to block websites. Thanks for letting me know I
just have to hunt for it.

I wonder why they removed that option from search results?

~~~
infogulch
No the option is completely gone, not just hidden. You have to use an
extension (which is what Google Personal Blocklist is).

~~~
toomuchtodo
Pesonal Blocklist Extension:
[https://chrome.google.com/webstore/detail/personal-
blocklist...](https://chrome.google.com/webstore/detail/personal-blocklist-by-
goo/nolijncfnkgaikbjbdaogikpmpbdcdef)

------
AYBABTME
This was a great read until I reached the truncated bottom of the post.

God I hate Quora. There's the `share=1` flag but still, the end of the article
is truncated and you're asked to login.

Quora wouldn't piss me off so much if they were not so annoying about me
logging in and linking a social account, if they didn't post crap from my
friend's facebook account who do have an account, send me spam about whatever
people I know might have done (or not done) on their platform.

This is trying to gather users by pissing them off. Likely I'd have created an
account since if it weren't for their aggressive behavior.

~~~
KhalilK
That's odd. On the page with the signup box look for the id
"__w2_LG4FatW_modal_signup_wrapper" and delete the whole div, that'll get rid
of the box allowing to you to continue reading the top answer but not the
others.

------
krat0sprakhar
Off Topic: Man! Reading this answer so makes me want to play those FlightSim
games of the yesteryears like Apache Havoc, Commanche, Jane's F/A 18 Hornet
etc etc. Does anyone have any suggestions for a modern Flight Sim game?
Thanks!

~~~
chrisan
Commanche was great. Strike Commander with a full Thrustmaster setup back in
the day was epic.

Games to keep an eye on (if you like combat)
[http://www.polygon.com/2014/6/9/5791924/e3-2014-marks-the-
re...](http://www.polygon.com/2014/6/9/5791924/e3-2014-marks-the-return-of-
the-flight-sim-genre)

Been out of games for a while, but looking forward to Oculus and whatever
today's Thrustmaster equivalent is :)

~~~
the_af
For being a "Wing Commander"-like game, Strike Commander was surprisingly good
and detailed. The manual was pretty interesting, with lots of information
similar to the Quora answer.

The hardcore side of combat flightsim gaming for me was Su-27 Flanker
([http://www.mobygames.com/game/su-27-flanker](http://www.mobygames.com/game/su-27-flanker)),
published by SSI. So hardcore I never actually managed to complete a full
mission! It was a bit dry, without any campaigns or any kind of career
tracking, but man was it detailed! It made me fall in love with the real-life
Flanker.

And of course, Falcon 3.0 by Spectrum Holobyte. Another awesome flightsim I
spent a lot of time with but never managed to complete a single mission with.
It was obvious this sim was a work of love.

------
chollida1
__Meta Note __

I 'm not sure if its the software or the OP who added the "?share=1" parameter
but thank you for including it in the link.

The flag makes reading quora possible. If HN doesn't add this parameter by
default I think it would be a worth while upgrade to the site.

Lots of great content is locked in quora otherwise.

~~~
readerrrr
Since quora has problems in the money department, how is their competitor
Stack Exchange maintaining profit?

~~~
serf
I don't know any numbers, but it seems as if Stack Exchange is far more
popular, especially as an information database for employees and students.

Quora has the opportunity to do the same, but I think the specific stack
exchange communities offer a better partition between topics. Quora does it's
best to show you targetted questions/comments, whereas StackExchange sites
just throw you wherever you showed up (which, if by search, is usually a
better choice)

A good example : I once answered a fringe question about the Dalai Lama on
Quora, now many of the questions i'm tasked with giving answers to are
spiritual in nature, and of absolutely no interest to me. It's the same search
bubble problem that YouTube/Google runs into occasionally. Things like that
make me prefer more 'basic' sites like StackExchange networks.

------
hueving
Is there any way to view the rest of the answer hidden behind the "more" link
without signing up for an account?

~~~
el_benhameen
I usually just open dev tools and delete the div that contains the modal
dialog and gray-out background (its ID is along the lines of
"Modal_signup_wrapper"). You still won't be able to read past the first
answer, but at least you'll get all of that answer's content.

------
Rapzid
Interesting(I didn't read the whole article because I'm not logging into
Quora). I wonder what the state of the art is? Certainly we have tech now to
get all the info on all the aircrafts? I would think that software could be
employed to fill in the gaps and extrapolate the info at the least. What with
3d video tracking and the like at the levels they are at today.

