Rafael Helispot

[lastdingo]

Rafael Helispot is/was an Israeli system for non-line of sight infrasound detection and triangulation of battlefield helicopters that was developed in several marks.

All I have about it is this:

https://irp.fas.org/agency/dod/jason/infrasound.pdf
mentions possible further source: "Srour, N. “HELISPOT MKII Evaluation of Helicopter and Ground Vehicle Detection”, US Army Research Laboratory, undated briefing"

https://defense-and-freedom.blogspot.com/2016/10/acoustic-sensors.html
which embedded this marketing brochure about Helispot: https://de.scribd.com/doc/6956942/Helispot

https://web.archive.org/web/2011082...ael.co.il/Marketing/186-931-en/Marketing.aspx
https://web.archive.org/web/2005103...el.co.il/web/rafnew/products/air-helispot.htm

• infrasound (non-line of sight)
• 360° coverage (all directions at same time, nothing rotates)
• 3° bearing accuracy
• up to 20 km range (minimum achievable range appears to be 4 km), very likely much-dependant on atmospheric conditions, esp. wind direction and speed, smallest claimed range was against MD 500 (known to be a rather silent helicopter, esp. with hush kit, it was likely tested against the MD 500M/TOW Defender that were in IDF use)

 

[lastdingo]

I should add that the topic is of renewed interest because

1. Non-line of sight missiles/drones can exploit the target data to endanger helicopters over a battlefield
2. Helispot was also claimed to work agaisnt RPVs, a.k.a. drones such as Shaheed-136.
3. The Ukrainians are known to use a distributed acoustic sensor network to track Shaheed cruise missiles (posisbly also conventional cruise missiles):

https://www.youtube.com/watch%3Fv%3DdHmJGyqwjY4

https://www.youtube.com/watch%3Fv%3DPduYzq-E1OM

https://www.reddit.com/r/ukraine/comments/1ed5pq0/ukraines_acoustic_drone_detection_network_eyed_by

View: https://www.reddit.com/r/ukraine/comments/1ed5pq0/ukraines_acoustic_drone_detection_network_eyed_by/

Ukraine’s cheap sensors are helping troops fight off waves of Russian drones

Sub-$500 rig helps save expensive air-defense missiles for bigger threats.

www.defenseone.com

Ukraine employs innovative network: Acoustic sensors for drone defense

General James Hecker is the chief of NATO's Allied Air Force Command and the commander of American air forces in Europe…

essanews.com

 

[Big_Zukini]

During the current war (October 7th, 2023 - present) on the Lebanon front, Hezbollah frequently used valleys close to the border and the Hermon mountain (which had split control between Israel and Syria) to launch drones and get them up to the border - at which point their interception was complicated as it would endanger civilians.
There was effectively a blind spot. Israel occupied the Syrian Hermon after the fall of Assad, which removed this blind spot.

If Israel was to deploy such acoustic detection system today, it'd probably be made suitable for higher frequencies such as those emitted by UAS and cruise missiles, particularly by smaller and faster props and probably along Mt Hermon outposts to make detection distance more relevant.

In 2011, Israeli defense giant Elbit invested in a small company Pearls of Wisdom, which developed small unattended terrain-blending ground sensors.





Apparently Elbit didn't see it as a dead end as 12 years later in 2023 it unveiled an evolved concept of more refined sensors and a dedicated drone delivery system.







These are reportedly in operational service, and the basic sensors last about 21 days.

 

[lastdingo]

Historically, acoustic sensors started as artillery locating systems (WWI), expanded to pre-radar aircraft detection & tracking through clouds capability (1930's, also UK during Battle of Britain behind the CH/CHL chain). During the 90's acoustic sensors became focused on detecting sniper locations (directions, the hype began with peacekeeping in Bosnia), often by measuring not the muzzle blast, but the sonic crack of the bullet.

Now Ukraine is using acoustic sensors as cheap trackers against cruise missiles (conventional and "drone" CMs), for it's so cheap and easily doable with mobile phone networks.

The infrasound helicopter detection never took off. Maybe everyone expects to have a look-down radar in the air, though that's clearly not often-enough the case in the Russo-Ukrainian War. Ukrainian AEW are propeller-driven adn cannot survive close to the front, Russian AEW is turbojet-driven, but still not survivable enough up front. Su-3x fighters patrol, but most likely don't have the datalink capability to SAM units with active radar seeker missiles up front to deter Ukrainian helicopters.

There are still new acoustic artillery locators from France, Israel, Ukraine and Russia, but no news about their employment.
examples https://www.thalesgroup.com/en/firesonic

How Russian 'Owl Ears' spot Ukraine’s guns—you won't believe

Russia’s BUH1a 'Owl Ears' system detects Ukraine’s guns daily with acoustic precision, staying hidden. Discover its upgrades and tactical impact now.

bulgarianmilitary.com

 

[timmymagic]

There are still new acoustic artillery locators from France, Israel, Ukraine and Russia, but no news about their employment.
examples https://www.thalesgroup.com/en/firesonic

One of the most popular is the Leonardo HALO from the UK. Used by 10 nations including UK, Canada and USMC.

It was used in Yugoslavia, Iraq and Afghanistan. Getting a deep refresh now as part of the UK's SERPENS system, alongside short and deep radar systems.

Halo

electronics.leonardo.com