Welcome to Doppler Systems' Web Site..
Established in 1981, Doppler Systems designs and manufactures radio direction finding equipment for amateur, commercial and government users. Fixed-site and mobile units are available for frequencies between 100 and 1000 MHz.
All of our direction finders operate on the simulated Doppler principle utilizing a patented constant impedance, smoothly varying RF summing unit for high sensitivity and high dynamic range.
Our 7000 series Multi Position Tracker (MPT) direction finder utilizes the latest technology to provide an accurate line of bearing to a radio frequency emitter. Depending on the antenna configuration it can be used as either a fixed site or a mobile direction finder. Multiple sites can be networked to provide geolocation of an RF source. In the fixed site configuration the DF antennas are mast mounted arrays of 8 biconical elements in a circular array with RF summing electronics embedded in the central hub ring. Fixed site DF's are always calibrated so that the line of bearing is relative to North.
The mobile configuration consists of the same processor coupled with a magnetically mounted summer and four vertical whip antennas. In mobile systems the DF's are calibrated so that the line of bearing is relative to the forward direction of travel of the vehicle. Factory calibration constants are built into the direction finder for many common receivers. USB host interfaces are provided to allow a GPS receiver, the DF receiver and a compass to be connected to the direction finder. A windows based software program is included that locates the tracking vehicle on a map and allows triangulation by displaying the lines of bearing taken from several locations.
The SignalTrack software suite provided with the direction finder allows the user to display the positions of the direction finders on a map. Then, using the bearing data provided by the DF and the heading and position data provided by the compass and GPS, SignalTrack calculates the position of the RF emitter. The software can be used with a single direction finder or a network of direction finders. Networking can be accomplished via an Ethernet based network or a network of radio modems.
The latest versions of all of our Windows based software programs are available for downloading from the Software page. These programs may be run in "playback" mode to see how they function. Firmware upgrades for the DFs may be downloaded from Firmware Upgrades. Hardware and software manuals are available for downloading in PDF format from Manuals.
Visit our Frequently Asked Questions page for a discussion of applications and some interesting technical issues. Also check out our Technical Application Notes for more detailed discussion of specific topics.
For more information on our products or to place an order, please see our Contact list.