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Doppler Systems LLC

Radio Direction Finders and Direction Finding Systems

The products on this page are no longer in production.  We do continue to support these products with customer assistance and repairs.  Contact the factory if you have need help with any of these products.

Series 6000 Radio Direction Finding System

The 6000 series radio direction finders provide microprocessor control for enhanced signal processing and remote control. These units are especially suited for remote site operation where multiple bearings are required for triangulation. A Windows based software program is provided with the unit that permits lines of bearing to be displayed on a map in real time.


The 6000 series is normally used at a fixed site  as shown in the following block diagram. Note that the fixed site shown is local to the PC (if used). It may also be remotely located using various type of networks.


DDF6001 Processor/Display

The DDF6001 display/processor drives the RF summer with the waveforms required to mix the four antenna inputs smoothly and to produce the simulated Doppler modulation at the selected sweep frequency. Audio from the receiver is processed to calculate a best estimate of the bearing angle. The DDF6001 may be used as a standalone fixed site without a PC, a homing type radio direction finder (using the RF Summer and Antennas shown with the Series 5900) or it can be used with the Bearing Track software. Typically, two to four remote fixed sites using DDF6001 processors are linked to a centralized PC to triangulate a signal. When used with an appropriate receiver, the series 6000 system meets the following specifications:

SignalTrack Software

This Windows based software program is supplied with the DDF6001. It provides real-time control and acquisition of bearing data from one or several remote direction finder sites. Remote site receiver frequencies may be changed, and all front panel direction finder controls are available. The software supports either Internet, data radio link, telephone line or direct (RS232) connection for control and data acquisition. When the direction finders are connected over the Internet, multiple users can access the bearing data simultaneously. Bearing Track triangulates bearings automatically and displays lines of bearings on commercially available digital maps. A least squares estimation of the emitter location and/or the 95% probability ellipse can also be shown. Data logging is provided for off line analysis. For more details on this program, refer to SignalTrack.

BrgTrack Screen Image

DDF6092/6095/6097 Fixed Site Antennas


These fixed site antennas contain the RF summing electronics in a sealed central hub. Elements are located at the end of eight arms rigidly connected to the hub. The antennas are shown mounted on the single mast adapter, DDF6216.

These antenna are normally provided with flexible whip type elements that are tuned to the nominal frequencies listed in the table below. If operation at a different center frequency is desired, please specify it at the time of order.

Model 6092 6095 6097
Frequency Range MHz 125-250 250-500 500-1000
Standard Center Frequency MHz 150 450 860
Bandwidth MHz 25 (+/-12.5) 100 (+/-50) 150 (+/-75)
Array Diameter mm (in.) 797 (31.37) 403 (15.87) 200 (7.87)
Element Length mm (in.) and type 889 (35.0) Dipole 305 (12.0) Dipole 73 (2.87) Monopole
Weight kg (lb.) 6.6 (14.5) 3.5 (7.8) 2.5 (5.6)

DDF6050 Two Antenna Stacking Hardware

The DDF6050 permits stacking two fixed site antennas at a DDF6001 site. The following antenna pairs can be accommodated:

Upper Antenna DDF6097 DDF6097 DDF6095 
Lower Antenna DDF6095 DDF6092 DDF6092

A heavy duty lower mast replaces the standard mast on the lower antenna, and coupling hardware and masts are used to connect the lower antenna to the upper one. A vertical separation of 0.94 m (37.3 in.) is provided between the two antenna hubs.

DDF6040 Three Antenna Stacking Hardware


Three fixed site antennas may be stacked on a single mast using this hardware. The antennas which may be stacked are:

Upper Antenna DDF6097 
Middle Antenna DDF6095
Lower Antenna DDF6092 

A heavy duty lower mast replaces the standard mast on the lower antenna, and coupling hardware and masts are used to connect the lower antenna to the middle one and the middle antenna to the upper one.. A vertical separation of 0.94 m (37.3 in.) is provided between the lower and middle antenna hubs. The vertical separation is 0.46 m (18 in.) between the upper and middle antenna hubs. 

DDF6079 Three Antenna Remote Switch


This switch connects to three fixed site antennas and is used to remotely switch both the control and the coax cables.  The DDF6079 may also be manually operated. LEDs indicate the switch status.

The unit includes a 15 conductor control cable for connection to J8, a stereo cable for connection to J9 and a BNC-BNC coax cable for connection to the receiver. All cables are 1.8 m (6 ft) long.