Kopáč (the word means "the digger" in Czech) was an early electronic warfare support measures (ESM) system developed in Czechoslovakia in the early 1960's that used measurements of time difference of arrival (TDOA) of pulses at three sites to accurately detect and track airborne emitters. Czech (ˈʧɛk čeština ˈʧɛʃcɪna in Czech is a West Slavic language with about 12 million native speakers it is the majority language in the In military Telecommunications the terms Electronic Support (ES or Electronic Support Measures (ESM describe the division of Electronic warfare involving Czechoslovakia may also refer to what is now the Czech Republic and Slovakia. Multilateration, also known as hyperbolic positioning, is the process of locating an object by accurately computing the time difference of arrival ( TDOA The system used the principle of multilateration and was capable of simultaneously manually tracking up to six targets. Multilateration, also known as hyperbolic positioning, is the process of locating an object by accurately computing the time difference of arrival ( TDOA It was first deployed in 1963 and was also known by its serial number, PRP-1. The initials PRP come from the Czech "Přesný Radiotechnický Pátrač", meaning "Accurate Radiotechnical Locator", the name comes from "Korelační pátrač", meaning "Correlation Locator".
The concept was derived by Vlastimil Pech and patented in Czechoslovak classified patent 771 on November 13th 1961. Subsequent related patents 830, 852 and 859 were filed by Vladimír Zárybnický in 1962. The system used analogue signal processing and operated in D, G\H and I\J bands, as well as specifically against IFF and TACAN transponders at 1090 MHz. D band is the range of radio frequencies from 1  GHz to 2 GHz in the Electromagnetic spectrum. NATO G band The G band in the modern (NATO/EU sense is the range of radio frequencies from 4  GHz to 6 GHz in the Electromagnetic The H band is the range of radio frequencies from 6  GHz to 8 GHz in the Electromagnetic spectrum. The I band is the range of radio frequencies from 8  GHz to 10 GHz in the Electromagnetic spectrum. The J band is the range of radio frequencies from 10  GHz to 20 GHz in the Electromagnetic spectrum. In Telecommunications, identification friend or foe (IFF is a Cryptographic identification System designed for command and control TACtical Air Navigation, or TACAN, is a Navigation system used by military aircraft The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second.
It remained in service with the Czechoslovak People's Army until 1979.