A STUDY LEADING TO THE CONSTRUCTION OF A TROPOSCATTER SIMULATOR.
Final rept. 1 Jul 66-30 Jun 67,
COMMUNICATION SYSTEMS INC PARAMUS N J
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The objective of this program was to study the requirements for and develop a new troposcatter simulator which reproduces the dynamic fading and multipath variations observed on tactical tropo hops of 50 to 200 miles using antenna beamwidths of 0.5 to 2.0 degrees, in a 10 MHZ RF bandwidth centered on the 70 MHz inputoutput frequency. A novel approach was used to overcome the limitations common to previous designs for simulation of dispersive media. An 81 path matrix provides continuously variable delay and attenuation under the real time control of a small stored-program digital computer DEC Model PDP-8 to reproduce the fine grain multipath and fading characteristics of the medium in accordance with a pseudo-random sequence which is precisely repeatable at the operators discretion. The result of this effort was a laboratory model which met all of the technical requirements including simulation of dual diversity, operator control of fad rate, median level, delay spread, aircraft doppler plus the ability to playback any desired portion of the simulated test run. There are no restrictions on the type of modulation digital or analog which may be tested since no fixed delays are used. The entire simulator is housed in a standard six-foot cabinet except for the external ASR-33 teletypewriterprinter which controls the PDP-8 computer. There are no controls, all operator functions being in the form of computer instructions. Author
- Test Facilities, Equipment and Methods
- Radio Communications