
Czech Passive Radar Detecting B-2 at 150 miles (2015) - enigmabridge
https://defence-blog.com/army/anti-stealth-radar-vera-ng-of-vietnam-in-action.html
======
ChuckMcM
Hmm, not your typical RADAR. This is basically using the RF emissions of the
plane, and their detection at multiple RF detection stations with synchronized
clocks, to determine the difference in arrival time. The radio emissions all
travel at the same speed through the air, the difference in arrival time can
be used with some simple trig to figure out where the RF emitter is. There are
a number of Time Difference of Arrival or TDOA systems out there. It is why I
expect aircraft stop using their radios when they are about to engage their
targets.

That said, they are "easy" to jam in the sense that when you have two radio
signals on the same frequency, they will interfere with direction finding. And
there is a lot of noise in the RF spectrum out there, especially during
thunderstorms.

~~~
JDulin
More to the point, detecting a stealth aircraft is very different from
shooting at a stealth aircraft.

This radar would likely not have the location accuracy of where _exactly_ the
B-2 was to accurately engage it with a missile. Your accuracy would be limited
by the rate of RF pings the B-2 is putting off, and then the margin-of-error
of these RF waves and receiver.

This is one difference between the B-2 and stealth fighters like the F-22 &
F-35: The latter are not necessarily designed to be invisible, only impossible
to reliably hit. Their shapes and radar-absorbent paint deflect, diffuse, or
absorb the high-frequency bands used in the terminal guidance of missiles. So
they are hard to target. But they can be picked up at range by long-distance,
long-wavelength VHF and UHF radars. These frequencies, used in early-warning
radars, have too low-optical resolution* however to be any good at aiming guns
or missiles. The B-2's "flying wing" shape is able to not-interfere with these
wavelengths though, and hence hides from them. In that sense, this is somewhat
interesting, if neutered for the reasons you mention.

*You can only localize the detection to a few sq hundred meters, even kms.

~~~
sfifs
If you can localize down to the range of a km? Can't you just shoot down
optically? A giant dark plane blotting out the stars...

~~~
nradov
An airplane at altitude doesn't blot out stars. Optical sensors are nearly
useless, especially against a black aircraft at night.

~~~
Enginerrrd
Not to sound skeptical, but I've seen some stuff Ratheon was putting out at
least 10-15 years ago and I think it had some pretty impressive optical
sensors. Are we including the various infrared frequencies?

~~~
nradov
Optical and infrared sensors have improved a lot and can be a useful
supplement but due to limited field of view and interference from weather you
generally can't count on them for primary search. Unless the target is really
time sensitive, B-2 mission planners try to fly at night in bad weather when
those sensors are seriously degraded.

------
whalesalad
The B2 is relatively ancient as far as stealth tech goes.

Also, most stealth aircraft are detectable on radar. The question is how big
or small is the radar cross section. That’s not something this blog post digs
into. Meaning, most of the time a B2 looks like a goose or a small animal.

Correction on my part: The B-2 and F-35 have radar cross sections roughly the
size of a marble.

~~~
willvarfar
A goose flying at 600mph?

~~~
HumblyTossed
It could happen:

[https://en.wikipedia.org/wiki/Chicken_gun](https://en.wikipedia.org/wiki/Chicken_gun)

~~~
dmos62
In that vein: cold-war era chicken-heated nuclear bomb (for area denial)
[https://en.wikipedia.org/wiki/Blue_Peacock#Chicken_power](https://en.wikipedia.org/wiki/Blue_Peacock#Chicken_power)

~~~
GekkePrutser
Oh dear.... Never heard of this but I'm glad the cold war is over.

"Alright chaps, let's bury some 10 kiloton nuclear mines in Germany in case
the Russians come.", From wikipedia: "deny occupation of the area to an enemy
for an appreciable time due to contamination"

"It was judged that the risks posed by the nuclear fallout and the political
aspects of preparing for destruction and contamination of allied territory
were too high to justify. "

Ummmmmm yeah WOULD YOU THINK???

"One particularly remarkable proposal suggested that live chickens be included
in the mechanism. The chickens would be sealed inside the casing, with a
supply of food and water; they would remain alive for a week or so. Their body
heat would, it seems, have been sufficient to keep the mine's components at a
working temperature."

Ok...... Now I'm really wondering if the Soviets were the crazy ones.

~~~
LargoLasskhyfv
I present you [https://foreignpolicy.com/2014/01/30/the-littlest-
boy/](https://foreignpolicy.com/2014/01/30/the-littlest-boy/) which also was
to be deployed into prepared shafts to make some area impassable. The keyword
here would be " _Wallmeister_ " for the people tasked with that mission.

~~~
dmos62
Entertaining. Excerpt:

> Cold War strategy was filled with oxymorons like "limited nuclear war," but
> the backpack nuke was perhaps the most darkly comic manifestation of an age
> struggling to deal with the all-too-real prospect of Armageddon. The SADM
> was a case of life imitating satire. After all, much like Slim Pickens1 in
> the iconic finale of Dr. Strangelove, American soldiers would strap on
> atomic bombs and jump out of airplanes as part of the opening act of World
> War III.

> From the Army's perspective, the problem was that bombers and missiles were
> managed by the Air Force and the Navy, leaving the ground force out of
> arguably the most significant development in the history of war, even as its
> soldiers would be chiefly responsible for stopping a Soviet invasion of
> Western Europe. Fortunately for the Army, many U.S. strategists still saw
> nukes simply as bigger conventional bombs, and America's post-Hiroshima
> mastery of the cutting-edge science of atomic destruction had filled weapons
> designers more with a sense of the possible than the prudent. The result was
> a series of odd creations that made their way into the Army's arsenal, from
> atomic artillery to nuclear-tipped air-defense missiles.

------
anonu
[https://en.wikipedia.org/wiki/Passive_radar](https://en.wikipedia.org/wiki/Passive_radar)

In a passive radar system, there is no dedicated transmitter. Instead, the
receiver uses third-party transmitters in the environment, and measures the
time difference of arrival between the signal arriving directly from the
transmitter and the signal arriving via reflection from the object.

Passive radar systems have been developed that exploit the following sources
of illumination:

    
    
      Analog television signals
      FM radio signals 
      Cellular phone base stations
      Digital audio broadcasting 
      Digital video broadcasting
      Terrestrial High-definition television transmitters in North America
      GPS satellites (GPS reflectometry).

~~~
jcims
You can build your own with rtl dongles and _lots_ of patience -
[https://www.rtl-sdr.com/building-a-passive-radar-system-
with...](https://www.rtl-sdr.com/building-a-passive-radar-system-with-an-rtl-
sdr/)

------
exabrial
A lot of countries posses radar that can detect stealth aircraft in a certain
area, but cannot be used to create a fire solution or even narrowing it down
to an area more than a couple square miles.

I believe as a design tradeoff, these planes are much more "invisible" (lower
radar cross section) at tracking and targeting radar wavelengths, which must
use much smaller frequencies.

------
mikeyouse
They do claim it works on all stealth planes including the F-35, but the B-2
is now _30 years old_ and was designed in the mid 1980s. Detecting it from 150
miles is impressive, but when they're equipped with 250 mile standoff air-to-
surface missiles, ultimately not very useful. I'd be curious how much better
the stealth is in the world of supercomputers and CFD for modern planes as
well.

~~~
kabouseng
Well it's passive radar. So you don't have to outperform the stand-off range
of the target, since you are invisible to the plane too.

~~~
nitrogen
Is there any risk of demodulator IF or other leakage from these receivers?

~~~
amluto
Given that it’s entirely reasonable to build a 3 GHz _baseband_ receiver these
days, you don’t need IF. The whole thing can probably be made to radiate
almost indistinguishably from a cell phone or computer.

~~~
londons_explore
A cell phone moving at that kind of speed will stand out.

~~~
nitrogen
Would a passive radar usually be moving?

------
galacticaactual
There is no evidence in the article to assert a B-2 was actually detected at
150 miles outside of unverified claims.

------
KingOfCoders
I think the current anti stealth capabilities are not clear, countries that
use anti stealth radar are not talking about the capabilities, e.g. what does
"The superior stealth target tracking capabilities ensure optimal performance
in demanding littoral environments." mean

[https://www.thalesgroup.com/en/netherlands/news/new-fire-
con...](https://www.thalesgroup.com/en/netherlands/news/new-fire-control-
radar-7-french-navy-frigates)

or "Within this enormous range it detects a wide spectrum of targets: air
breathing targets, stealth targets and ballistic missiles."

[https://www.thalesgroup.com/de/smart-l-multi-mission-
radar-0](https://www.thalesgroup.com/de/smart-l-multi-mission-radar-0)

or "It is also claimed to be highly capable of detecting stealth targets"

[https://en.wikipedia.org/wiki/S1850M](https://en.wikipedia.org/wiki/S1850M)

~~~
baybal2
> "performance in demanding littoral environments"

This is a defence contractor 1337 sp33k for "Works well in the South China
sea"

------
nradov
Many people fail to understand that there's a huge difference between
detecting the presence of an aircraft and actually targeting it. Anti-aircraft
weapons must be precisely targeted to have any chance of hitting. So a passive
radar can be useful in limited circumstances for cueing other sensors but it
can't accomplish much by itself.

~~~
m4rtink
Could the adversary still just send cannon equipped fighters to the general
that would locate the stealth bomber visually and shoot it to pieces ?

Sure, could be rather hard to do in the night but once a stealth bomber is
sighted visually, it is toast - B2 simply has no self defence weapons
available at all.

A stealth fighter could be better off if it can defend itself while still
avoiding others getting a weapon lock, effectively forcing them to use
visually sighted cannon while it can use sensor guided gun and missiles
normally.

~~~
nradov
That's the type of tactic that mostly only works in movies. In the real world
interception is very, very hard just due to geometry. Fighters have limited
fuel supplies and don't move much faster than bombers. Any no country can
afford to keep a lot of them in the air or even on alert status at any given
time. So the circumstances have to line up pretty well to get an interceptor
in the right place at the right time.

And even then, aircraft like the B-2 are difficult targets to actually hit. At
high altitudes they are fairly maneuverable due to low wing loading.

~~~
m4rtink
Well, existing stealth bombers (basically B2 at this point) are sub sonic
while many fighters are super sonic.

As for range - that's a good point, if your low fregvency or passive radar
gives you a big bounding box, your fighters could run out of fuel before they
find the stealth bomber. Or it might drop/launch its payload before you catch
it.

~~~
nradov
Supersonic dash capability can help in some limited circumstances but it
doesn't fundamentally change anything. Fuel consumption at those speeds is
extremely high.

------
whalesalad
> Jamming hard and almost impossible to be destroyed by the anti-radiation
> missiles kill radar. Positioning and stick to the target in the air, on land
> and sea surface perfectly, providing enough parameters in real time.

This post is really quite garbage.

------
LyndsySimon
That reads like a badly-translated press release. I don’t buy it.

------
lazyjones
What would air defence against a swarm of a few 1000 UAV look like? Because
China...

~~~
Retric
Drones represent a huge range of different things. Assuming you mean something
that’s a replacement for military aircraft.

In order to have a useful X,000miles range and useful payload you need to
build fairly large drones which means a large target. If their cheap that
directly translates into low speeds making them a very easy target for anti
air guns, or low cost anti aircraft missiles.

If you want a large fast drone, that’s getting expensive. To the point where
having or not having a pilot makes minimal cost differences.

Note, this assumes it’s part of a modern war with extreme radio jamming etc.

~~~
rblatz
Why would you not deploy smaller drones via another platform?

Small cheap disposable drones are a game changer. Drop them on a military base
and have them seek and distort any human shaped targets, any sources of RF
radiation, anything that looks like a vehicle or plane...

~~~
chmod775
> Drop them on a military base

If you can get close enough to drop a bunch of slow drones, you can get close
enough to just drop a bomb on the whole thing instead. Much more bang for your
buck.

Let's also not forget that small drones might become 'banned' much like
chemical weapons did, if they ever became viable.

~~~
nradov
Small drones will never be banned by international treaty. There is zero
chance of that.

~~~
ClumsyPilot
Lasers were banned. Where does your certainty come from?

~~~
nradov
Lasers were not banned and are more heavily used now than ever before. Only
_blinding_ lasers were banned by treaty, and even with those China is semi-
openly defying the ban.

~~~
Retric
“Please respond to the strongest plausible interpretation of what someone
says, not a weaker one that's easier to criticize. Assume good faith.“

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

It’s clear what they where referring to, as the argument was a type of drone
being banned not all drones. Saying they “banned lasers” is correct even if
they only banned a subset of lasers.

I am genuinely curious if you have a deeper argument. As small anti personnel
drones seem suspiciously close to cluster munitions, but might be acceptable.

~~~
nradov
It was not even remotely clear what they were referring to. There are many
different types of lasers.

Considering that the US, Russia, India, and China haven't even signed the
Convention on Cluster Munitions there's clearly no political appetite for such
bans among countries with large militaries. And such a ban would be
unenforceable anyway because small drones are dual use technologies which
don't require specialized manufacturing.

------
thedance
What's the mission and purpose of the B-2 these days? It's a penetrating
strategic bomber. The justification for it was that it could strike mobile
Soviet ICBM launchers. It was never going to be any good for that. What's it
for now? Has it ever been used against a sophisticated enemy (i.e. not people
who are literally living in caves)?

~~~
gsnedders
It's combat debut was during the Kosovo War, which was clearly _not_ people
who are literally living in caves, during which the F-117 suffered its only
combat loss, shot down by anti-aircraft missiles, successfully tracked by the
radar.

~~~
thedance
OK, but what's it good for today? Kosovo was 20 years ago. If the B-2's role
is to fly conventional missions, the MQ-9 can be armed with the same weapons
that the B-2 carries.

~~~
openasocket
Getting inside an integrated air defense network to take out strategic
targets. It's got what is believed to be a better stealth profile than the
f-22 or f-35, while having payload comparable to a b-52. The MQ-9 wouldn't be
able to get anywhere close to an air defense network.

~~~
thedance
OK I'm convinced. What's the 52 for, then?

~~~
openasocket
Large scale strikes also, but after air defenses have been taken down, or
suppressed by SEAD escorts. Keep in mind we only have 21 B-2s and they are
very expensive to maintain, so it makes sense to use the B-52 whenever
possible.

------
rich_sasha
There is also a matter of accuracy. I believe stealth planes are often
“detectable” at longer frequencies, which however do not give precise enough
information to fire a missile at them. So you’ll know they are coming but
can’t shoot them down. I would imagine radio signal triangulation falls into a
similar category.

------
enigmabridge
You don't necessarily need the aircraft to emit any signals, you may be able
to detect changes in the background RF emissions reflected or distorted by the
aircraft. It would have to be enormously CPU expensive but if you can
correlate changes in tens or hundreds of frequencies, I can imagine it could
be done.

------
spiderfarmer
2016: [https://www.cnbc.com/2016/09/21/the-end-of-stealth-new-
chine...](https://www.cnbc.com/2016/09/21/the-end-of-stealth-new-chinese-
radar-capable-of-detecting-invisible-targets-100km-away.html)

------
baybal2
150 miles is not that much

------
DailyHN
2015

------
GekkePrutser
Who wrote that article? It reads like Chinese that was put through a bad
version of google translate.

I mean really who uses 'cum' in an official article (even though it's not in
an NSFW context and technically used correctly). It's a word that has fallen
into disuse because its 'other' use has taken over its association entirely :)
You won't find this in a serious publication.

And this "Distance reconnaissance: 400 km with 20 m wrong; Number of goals can
stick to 200 targets simultaneously."

Whatever it is, this ain't English.

~~~
frandroid
cum qa become remains in common use today.

