Passive radars

Most medium-to-large warships usually have an Early Warning/Volume Search radar in addition to the main one for long-range target detection. While researching such systems I came across a certain peculiarity: Modern Russian ships generally use the 3Ts-25 Garpun and Mineral-ME volume search radars, which advertise a passive detection capability.

Aside from the usual radar transmitting antenna, these systems have an additional antenna element that simply receives signals from other radars, identifies and pinpoints them, like a passive listening station. This enables them to detect targets as far as 450km using their own radar emissions.

I don’t know the specifics of how such systems work, but in theory it seems to me an excellent idea for today’s warships, hearing all the praise about how powerful and long-ranged modern radar systems like the Type 45’s are. Why is it that there is no Western analogue to such systems i.e. a passive radar system for the volume search role?

Afaik, Mineral ME and Garpun are 2D (range and bearing) radars used specifically for OTh AShM targeting. For which Western ships tend to use organic heliborne radar and shipborne 3D radar and ESM and networked off-board RADAR/ELINT/ESM assets.

Mineral ME does have a back-to-back arrangement of antennea.
See this at p272

Great book, that. If only I had the funds to buy it…

Seeing the structures above and behind the parabolic dish I was under the impression it had two separate antennas. But do ESM suites have an effective range of upto 500km? And can they pinpoint the locations of radar emitters with the same level of accuracy under heavy clutter?

Mineral ME does have a back-to-back arrangement of antennea.
See this at p272

No, that is a fundamental principle which affects all radar and ESM systems. Simply put, consider a radar with a maximum detection range of 100km, its receiver must be capable of detecting a return signal that has travelled 200km – from the antenna to the target and back again. From this it follows that an ESM system fitted with a receiver of similar sensitivity would be able to detect the above radar from a distance of 200km.

“Traditional pulsed radar systems have suitable amounts of transmitter power to enable them to meet their design objectives. A small pleasure vessel’s radar used in confined waterways and for coastal navigation might have a peak pulse power of only 4 kiloWatts whereas a long-range air surveillance radar might pack well over 2 MegaWatts. Given general propagation conditions, an ESM system will detect pulsed radar systems at around twice their target detection range.”

… I wonder what the point of these radars was then. Were Soviet ESM systems unreliable?

Seeing the structures above and behind the parabolic dish I was under the impression it had two separate antennas. But do ESM suites have an effective range of upto 500km? And can they pinpoint the locations of radar emitters with the same level of accuracy under heavy clutter?

According to the brochure for 3Ts-25E Garpun, active surface target detection range (against target RCS – 1,000 sq. m) is 35-45km in normal radar visibility, up to 90km in high radar visibility and up to 250km in conditions of super-refraction (depending on the area covered). Surface target detection range in passive mode is 50-500km, depending on signal potential and frequency band of electronic equipment emissions.

That is, depending on what band and how strong an emittor. In addtion, it would make a difference how high up on the ship the equipment is mounted. And how high up the emitting target is (ship > close to sea level, aircraft e.g. 10km). Of course at 500km accuracy will be less.

“Traditional pulsed radar systems have suitable amounts of transmitter power to enable them to meet their design objectives. A small pleasure vessel’s radar used in confined waterways and for coastal navigation might have a peak pulse power of only 4 kiloWatts whereas a long-range air surveillance radar might pack well over 2 MegaWatts. Given general propagation conditions, an ESM system will detect pulsed radar systems at around twice their target detection range.”
http://www.ausairpower.net/APA-Maritime-ESM.html

500 km is not an unusual detection range for passive systems (ESM/ELINT). See e.g. http://www.ausairpower.net/APA-Warpac-Rus-PLA-ESM.html (some of the tables are particularly informative e.g. for 85V6 Vega / Orion ELINT System and Lantan/Almaz-Antey Valeria E ELINT and Emitter Locating System

Seeing the structures above and behind the parabolic dish I was under the impression it had two separate antennas. But do ESM suites have an effective range of upto 500km? And can they pinpoint the locations of radar emitters with the same level of accuracy under heavy clutter?

I was fairly sure both active and passive radar could be installed on the same ship. That’s how it is with the Garpun-B, anyway.

It is not 2 radars but a single radar that can operate actively (i.e. emit and receive) as well as passively (receive only, with another radar elsewhere – friebdly or otherwise – acting as emittor). In that sense, it is no different from dedicated ESM gear, except that it is integrated into a radar system.

From your own source:

Composition
• active radar channel
• passive radar channel
• equipment used by both channels (multiband dish antenna, control panels, power management unit, antenna hydraulic drive, high-frequency channels, and offset antenna)

The radar makes coordinated use of active and passive channels to acquire and designate targets. It boasts increased operational range thanks to employment of high-energy active channel, advanced methods of signal generation and complex modulated signal processing, coupled with passive channel data, and requirements of covert operation, in severe ECM and sea clutter conditions.
The active channel uses a multiprocessor system to generate probing signals and radar data. It is integrated with a multi-computer secondary data processing, control and display network.
The passive channel performs hardware/software-based analysis and classification of incoming radar signals by comparing their parameters with those available in the database (up to 1,000 entries).

OK, thanks for the additional info.

Your first post made no mention of data-linking from another ship that was using an active radar.

This is indeed much like having a grunt on the ground using a hand-held laser designator to “paint” a target, with a jet carrying laser-guided bombs and a laser receiver using the second-hand info to hit the target.

Its just a more advanced version… and should work pretty well.

However, the “active” ship would not be a nice place to be… unless you rotate the job between several data-linked ships.

Hmmm…

I was fairly sure both active and passive radar could be installed on the same ship. That’s how it is with the Garpun-B, anyway.

OK, thanks for the additional info.

Your first post made no mention of data-linking from another ship that was using an active radar.

This is indeed much like having a grunt on the ground using a hand-held laser designator to “paint” a target, with a jet carrying laser-guided bombs and a laser receiver using the second-hand info to hit the target.

Its just a more advanced version… and should work pretty well.

However, the “active” ship would not be a nice place to be… unless you rotate the job between several data-linked ships.

Hmmm…

Mineral-ME shipborne radar system is intended to control missile armament system and provide over-the-horizon early radar acquisition and target designation on virtually all types of ships.

The system comprises:
– Mineral-ME1 active radar (ARdr),
– Mineral-ME2 passive radar (PRdr),
– Mineral-МЕЗ data exchange and orientation radar (DEORdr).

All radars are built around a single design base

Active radar

Passive radar

Datalink

Courtesy http://www.concern-agat.ru/en/production/75-typhoon/91-mineral-me

It still is like ESM integrated into a weapons targeting radar: someone else will do the active bit.

No, I’m not talking about EW suites but purpose-built passive long-range radars.

That only works if the incoming aircraft are radiating in the radar frequency ranges.

If they are “running silent”, than the ship depending on the passive system is blind.

Which is why the passive system is paired with an active radar antenna.

” Electronic Support Measures (ESM) describe the division of electronic warfare involving actions taken under direct control of an operational commander to detect, intercept, identify, locate, record, and/or analyze sources of radiated electromagnetic energy for the purposes of immediate threat recognition (such as warning that fire control RADAR has locked on a combat vehicle, ship, or aircraft) or longer-term operational planning.”
http://en.wikipedia.org/wiki/Electronic_Support_Measures

You are describing a system like the SLQ-32(V)2 or higher. Lots of countries use it or a system like it.

That only works if the incoming aircraft are radiating in the radar frequency ranges.

If they are “running silent”, than the ship depending on the passive system is blind.

That’s why the USN built the E-1 Tracer and then replaced it with the E-2 Hawkeye… they fly scores of miles away from the carrier and do the volume-search mission, while the carrier shuts off all its radars.

The E-2 sends a data-stream to the carrier allowing them to see everything the E-2 sees, but the carrier itself is not transmitting anything, and is therefore much harder to find, while still seeing everything that is going on!