Receivers ESM-ELINT » Frequency Measurement Modules »

Activity Detection


Many advanced EW receivers, particularly those associated with ECM jamming systems, do not require the high resolution frequency information associated with a DFD or IFM based receiver. This is typically the case where a single pulse present within a broad frequency band is required to be detected and instantaneously down-converted to an IF band.

TDS manufactures a range of Frequency Activity Detectors (FADs) also known as Activity Detection Units (ADU) which perform frequency measurement of an RF pulse and output data in as little as 15ns. The basis of these products is TDS’s ability to produce high performance broadband channelisers and integrated detectors. These devices are ideal for receivers which must operate in very high pulse density environments.

The FAD consists of an RF input, which may be fed by a signal conditioning network as in the case of the IFM. This is followed by a detector integrated into each channel and a combination of video and logic circuitry. If any particular channel has crossed a predetermined threshold a trigger is created. A crucial element in the design is the channel filter characteristics and their contiguous frequency coverage, eliminating false triggers.

The FAD can be configured by TDS to drive switched multiplexers and frequency synthesizers directly for the ultimate high speed set-on and adaption.


Activity Detection

  • Airborne transport environments
  • Electronic support measures (ESM)
  • Electronic counter measures (ECM)

Features & Benefits

  • Provides indication of RF signal presence
  • Coarse frequency measurement
  • Ultra low false alarm rate
  • 2 to 16 GHz Coverage
  • 16 Channels
  • 250 MHz Channel bandwidths
  • 50 ns pulse width capability
  • Programmable threshold of 32 levels over 16 dB Window
  • Selectable video detection bandwidths



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