Accession Number : ADA259083


Title :   Computer Simulation of a General Purpose Satellite Modem


Descriptive Note : Master's thesis


Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING


Personal Author(s) : Montgomery, Jr, William L


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259083.pdf


Report Date : Dec 1992


Pagination or Media Count : 138


Abstract : The purpose of this research was to model and simulate the performance of a digital phase shift keyed satellite modem. The probability of bit error (P sub b) at different levels of energy per bit to noise power ratio (E sub b/N sub o) was the performance measure. The channel was assumed to contribute only additive white Gaussian noise. A second order Costas loop performs demodulation in the modem and was the key part of the simulation. The Costas loop with second order Butterworth arm filters was tested by finding the response to a phase or frequency step. The Costas loop response was found to be in agreement with theoretical predictions in the absence of noise. Finally, the effect on P sub b of a rate 1/2 constraint length 7 convolutional code with eight level soft Viterbi decoding was demonstrated by the simulation. The simulation results were within 0.7 dB of theoretical. All computer simulations were done at baseband to reduce simulation times. The Monte Carlo error counting technique was used to estimate P sub b. The effect of increasing the samples per bit in the simulation was demonstrated by the 0.4 dB improvement in P sub b caused by doubling the number of samples.... Modem, Computerized simulation, Convolution, Encoding, Costas loop, Coding, Phase modulation.


Descriptors :   *COMPUTERIZED SIMULATION , *SATELLITE COMMUNICATIONS , *MODEMS , FREQUENCY , PREDICTIONS , PERFORMANCE(ENGINEERING) , PROBABILITY , ENERGY , POWER , CONVOLUTION , DECODING , PHASE SHIFT , PHASE MODULATION , CHANNELS , DEMODULATION , FILTERS , GAUSSIAN NOISE , THESES , MONTE CARLO METHOD , ESTIMATES , ERRORS , ARTIFICIAL SATELLITES


Subject Categories : Radio Communications


Distribution Statement : APPROVED FOR PUBLIC RELEASE