Modeling and Data Analyses - Short and Medium Range Digital Troposcatter Tests. Volume I.
Final rept. Jun 67-Feb 69,
SIGNATRON INC LEXINGTON MA
Pagination or Media Count:
The report concerns the modeling of troposcatter channels and modems together with data reduction efforts connected with a series of tests conducted at the RADC troposcatter test bed between September 1967 and March 1968. Two high speed digital data techniques were tested in addition to data transmission over the conventional FDMFM system. Limited channel measurements were taken concurrently with data transmission by utilizing the received signals. Mathematical models were developed for the modem receivers which accounted for all critical determinants of system behavior. Such factors as AGC, non-linearity of detectors, non-ideal combining, inter-symbol interference, and others were included. The complex Gaussian scatter channel model was used in conjunction with experimentally determined median envelope frequency correlation functions to form a mathematical channel model. With the aid of the mathematical models, theoretical predictions of error rate and error rate scatter were made. It was found that the observed error rate scatter occupancy was consistent with that predicted theoretically for 20-minute measurement time per error rate sample. As a result of the knowledge gained on this program, it is concluded that new approaches must be made to the comparative evaluation of modems which alleviate the error rate scatter problem. Author
- Radio Communications