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Radio Direction Finding Systems
Welcome to Doppler Systems' Web Site..
Established in 1981, Doppler Systems Inc. designs and manufactures radio direction finding equipment for amateur, commercial and government users. Fixed-site and mobile units are available for frequencies between 50 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. Three series are currently offered.
Our new 5900 series is micro-processor controlled and accommodates signals up to 1000 MHz. The main processing unit is contained in a low profile metal enclosure that connects to the receiver, the rf summer and a remote display unit. The remote display is a miniaturized unit which presents the bearing in both an LED compass rose and digital format and the signal strength on a colored LED bar graph. It also contains a loudspeaker, and it can be mounted on the windshield using a double pivoted mounting arm. The RF summer is housed in a separate sealed metal housing that is located near the antenna. Both fixed site and mobile antennas are available. All antennas use four monopole or dipole elements.
The 6000 series utilizes an embedded controller to provide superior signal detection and bearing angle measurement. This system can also be used fixed site or mobile. Fixed site antennas contain eight dipole elements and the RF summer is contained in the antenna mounting hub. Dual serial interfaces are provided for remote control of both the direction finder itself and its associated receiver. A Windows based software program is included that provides centralized control and triangulation of bearings from multiple remote DF sites using map overlays.
The latest version of this software provides Internet connection capability in addition to radio modem, phone line and direct (RS232) connection. The program also displays the least squares estimation of emitter location and a 95% probability ellipse. Data logging is also provided.
The 6100 series is intended for mobile radio direction finding utilizing GPS, a laptop PC, and optionally a flux gate compass. This system is similar to the 6000 in that it uses an embedded controller for signal processing, but it provides multiple RS232 interfaces so that the GPS, compass, receiver and direction finder data can be multiplexed into a single laptop computer COM port. 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.
For more information on our products or to place an order, please see our contact list.
In late 2001, we introduced new model numbers in both the 6000 and 6100 series. These new models are very similar in appearance and operation to the preceding models, but the electronics have been modified in both the RF summing electronics and the display/processor. The reason for making this change is that some of the parts used in the previous models were becoming difficult to obtain. The same software will work with either model, and in the case of the series 6000, they may be combined in the same network. The new and old models cannot be directly interchanged, however. For example, a new DDF6001 processor cannot be used with an older DDF6052 antenna. To prevent accidentally connecting an old antenna to a new processor or visa versa, we have changed the sex of the control cable connectors. Do not defeat this protection by attempting to use an adapter. We continue to support the earlier models of these products, of course.
New versions of all of our Windows based software programs have recently been released and are available for downloading from Software Upgrades. The latest version of the firmware used in the form of EPROM upgrades 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.