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 Adur Communications Upper Beeding West Sussex BN44 3WH
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Doppler Systems Radio Direction
Finding Equipment Adur Communications have been appointed as the exclusive distributor in the United Kingdom for the direction finding equipment from Doppler Systems Inc. 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, utilising a patented constant impedance, smoothly varying RF summing unit for high sensitivity and high dynamic range. Three systems are currently offered. 5900 Series Simple Mobile/Fixed Site 6000 Series Advanced Fixed Site 6100 Series Advanced Mobile 5900 Series  The 5900 series features wide frequency coverage using a remote RF summing circuit. The summer is available with a magnetic mount for mobile operation. A wide range of antennas is offered to cover frequencies between 88 and 1000 MHz. This series is recommended for low cost homing from a vehicle. (The series 6000 direction finder should be used when remote operation and/or triangulation is required). A complete setup requires a processor, a remote display, an RF summer, and an antenna. A narrow band fm receiver is also required. Good quality scanners, transceivers, service monitors, and spectrum analyzers can be used; however, care must be taken to avoid transmitting into the direction finder if a transceiver is used. Features Remote display of bearing angle and signal strength Broadband - covers 88 to 1000 MHz 5 deg bearing accuracy (1 sigma, no reflections) Digital processing for high sensitivity and multipath reduction Notch filter eliminates tone from built-in speaker output Selectable moving average and RF attenuator To download the operation manual please click on this link 6000 Series  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. Features Broadband - 125 to 1000 MHz. All functions remotely controllable. Selectable commutation frequency for optimum match to signal conditions. 2 deg bearing accuracy (1 sigma, fixed site). Software for fast data acquisition from multiple sites and automatic triangulation to locate source on digital maps. Controllable signal averaging reduces multipath effects in mobile use. Front panel display of bearings in digital and compass rose format, and signal strength on scale of 0 to 9. Two data ports provide serial input and output in ASCII and CIV formats. Rugged, weather-resistant fixed site antennas include built in summer electronics and 8 elements. 4-element mobile summer is magnetically mounted in separate sealed enclosure. Notch filter eliminates commutation tone from audio output of built-in speaker. To download the operation manual please click on this link 6100 Series  The 6100 series radio direction finder provides a self contained system for mobile triangulation. Utilizing the AutoTrack software program running on the user's laptop computer, lines of bearing may be recorded on a digital map. A GPS receiver is used to measure the tracking vehicle's location and heading which are displayed as an icon on the map. Lines of bearing (LOB) are also shown on the map originating from the icon. When the user determines that a valid bearing is displayed, the LOB is stored and the icon changes. By driving to another location and taking another LOB, the intersection indicating the emitter location is found. This process continues as the tracking vehicle closes on the emitter. The number of LOBs displayed may be limited to show only the most recent; however, all selected LOB data is written to a file that may be recovered later for analysis of the data. Features Broadband - 88 to 1000 MHz All functions controllable from laptop Selectable commutation frequency for optimum match to signal 5 deg bearing accuracy (1 sigma) Includes AutoTrack software Controllable signal averaging reduces multipath effects Multiplexes four auxiliary serial ports (3 RS232 and 1 CIV) with direction finder data to laptop Integrated low profile antenna platform available Distributes 12 VDC power to all components from single cigar plug outlet To download the operation manual please click on this link Theory of Operation Four or eight omni directional antennas are arranged in a circular array and are connected to an RF combining or "summer" circuit. The summer combines the antenna signals in a way which simulates the continuous rotation of a single antenna element about the axis of symmetry of the antenna array.Rotating Antenna  In the simplified figure, a single antenna element is shown rotating in a circular path. As the element approaches the incoming rf wavefront, a frequency increase occurs, and when the element travels in the same direction as the wavefront, the frequency decreases. This up-down frequency shift or modulation occurs at the rotational frequency of the antenna. Applying the modulated RF signal to the input of a narrow band fm receiver produces a component in its audio output at the antenna rotation frequency (sometimes called the commutation or sweep frequency). This tone is superimposed on the normal audio output and the phase of the tone (relative to the clock reference used to commutate the antenna) is the bearing angle. The direction finder processes this audio signal to calculate and display the bearing angle. There are two connections to the receiver. The antenna output connects to the receiver's antenna jack and the audio output at the receiver's loudspeaker is taken to the direction finder audio input. Typically, the external speaker jack is used for this connection. For further details including specific requirements of operation on any of the systems, please contact us. |
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  PMR-WEB A new software application designed to give advanced functionality for the management process of radio communications systems - more info 
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