OVERVIEW: The KRTP-81M Ramona (NATO: SOFT BALL) ELS is a is a transportable, ESM system for passive direction finding and locating airborne emitters operating in the C-J (NATO) or UHF-KU (IEEE) bands. 

DETAILS: The KRTP-81M is an improved version of the KRTP-81.  Like the KRTP-81, the KRTP-81M uses Differential Time of Arrival (DTOA) capabilities to locate both airborne and surface emitters. The KRTP-81M, has higher sensitivity (+ 3dB) and higher resistance to interference, improved performance against TACANs and improved software.

The deployed system typically comprises a central site containing the signal processing equipment and an ESM receiver and two or three side sites containing only an ESM receiver. The receivers typically are targeted against emitters such as secondary surveillance radar (SSR) transponders, identify friend or foe (IFF) transponders, airborne radars, weather radars, tactical air navigation (TACAN) transponders, distance measurement equipment (DME) beacons, digital communications signals, and pulsed jamming signals.  The received signals are transmitted to the central site over a microwave link. 

The central site uses the known propagation delay from the side sites to estimate the TDOA of the pulses at each site. The TDOA of a pulse between one side site and the central site locates the target on a hyperboloid. A second side site provides a second TDOA and hence a second hyperboloid. The intersection of these two hyperboloids places the target on a line, providing a 2D measurement of the target's location (no height) or a 3D location with reception from 3 or more receivers.

 The side sites are usually deployed 15-40 km from the central site, providing a compromise of coverage and accuracy.  Up to 20 targets can be automatically tracked.

In contrast to the successor KRTP-86 TAMARA, RAMONA was palletized and loaded on a total of 13 three-axle trucks and required 4-12 hours for operation. 


Specifications:

Frequency: 		 80 MHz-18 GHz (B-J Bands (NATO); UHF, L, S, C, X, KU Bands (IEEE)))  
	
Range Resolution:	 unknown m (range), unknown degrees azimuth 					
On/Off time:		 unknown
Deploy/Stow Time	 4-12 hours
Max Range:		 240 nm (radar horizon)

NOTES:  IOC 1980. A total of 17 KRTP-81s, 14 KRTP-81Ms and a training system were produced. 

SOURCES:"CZK - KRTP-81 Ramona (radiotechnický Pátrač)." Https://www.valka.cz. Accessed September 22, 2021. https://www.armedconflicts.com/CZK-KRTP-81-Ramona-radiotechnicky-patrac-t12985. ; "RAMONA." Homepage Manfred Bischoff. Accessed September 22, 2021. https://www.manfred-bischoff.de/RAMONA.htm. ;"Czechoslovak passive electronic intelligence stations." Accessed September 22, 2021. https://pvo.guns.ru/other/czech/tamara/. ;  Kopp, Dr C. "Warsaw Pact / Russian Emitter Locating Systems / ELINT Systems." Air Power Australia. Accessed August 9, 2021. https://www.ausairpower.net/APA-Warpac-Rus-PLA-ESM.html#mozTocId797754.

