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Doppler Systems LLC

Radio Direction Finders and Direction Finding Systems

VHF/UHF/THF Fixed Site Direction Finders

Our VHF/UHF/THF direction finders typically are installed in permanent or semi-permanent locations where the antenna has a relatively clear view of the surrounding  area and RF obstructions and reflectors are minimal.  Three stackable antennas mounted on top of a mast, tower, or building cover 115 - 1000 MHz. in three frequency bands.  It can be remotely operated via an Ethernet or radio-modem connection.  Networked with other fixed site or mobile direction finders and utilizing our TargetTrack software facilitates geolocation of the targeted RF emitter. 

The direction finder is available as a packaged system containing everything necessary to install and operate a fixed site direction finder or it can be purchased as components and integrated by the user.

Fixed Site Direction Finder Components
Fixed Site Radio Direction Finder Components

Windows based software is provided with the direction finder allowing the user to configure the direction finder and display the bearings on a map based display.  The software tunes all networked sites to the same frequency and bearings from these sites are used to predict the location of the RF source.   

Multiple direction finder processors and receivers can be connected to a single antenna permitting simultaneous direction finding on up to 32 frequencies.


DF Method Synthetic-Doppler with patented "Smooth Summing"
Frequency Range 115 - 1000 MHz
Accuracy < 1 deg rms  (115 - 500 MHz)
  < 1.6 deg rms  (500 - 1000 MHz)
Resolution 0.1 deg
Sampling Rate 2 samples per second
Sensitivity -123 dBm (FM receiver dependent)
Averaging Adjustable from 1 to 20 samples
RF pulse detection 100 ms minimum
Commutation frequency Adjustable (250, 500, 1000, 2000 Hz)
Voltage Range 11 - 14 VDC
Power 6.5  W @ 12 VDC (processor and antenna)
Temperature Range -25 °C to 85 °C (antenna)
CE Compliant

Per EN 61000-6-2, EN 61000-6-4 AND EN 301 489-1