Partial-band Multitone Jamming Research Articles

On the probability distribution of differential phase perturbed by tone interference and Gaussian noise

This paper presents a novel method for determination of the general probability distribution of a received differential phase corrupted by both continuous tone jamming and Gaussian noise. An alternative and yet simple expression is derived for this general probability distribution. As an example of its application, we analyze the error performance of a general uncoded SFH/DPSK system under partial-band multitone jamming.

Performance analysis of frequency hopped/coherent MPSK in the presence of multitone jamming

This paper studies the performance of frequency hopped/coherent M-ary PSK signals in the presence of partial-band multitone jamming. The probability density function for the jammed received signal phase is found and utilized in obtaining a probability of error expression. The analytical expressions to assess the performance under worst case multitone jamming are provided.

Optimization of a hybrid SFH/DS MFSK link in the presence of worst case multitone jamming

The performance of a hybrid slow frequency hopped direct sequence multiple frequency shift keyed (SFH/DS MFSK) communication link in the presence of partial band multitone jamming is considered. The communication signal is characterized by a DS-spread MFSK signal bandwidth that may exceed the FH slot spacing, and the signal consists of multiple M-ary symbols per DS code period. An equation for the bit error rate (BER) is developed for the signal in the presence of multitone jamming. The equation is flexible enough to allow examination of optimization of jamming strategy. It is shown that the jamming strategy may be optimized by varying the number of tones, their placement, or both. It is shown that in the presence of optimized jamming, overlapping systems are more resistant to jamming than nonoverlapping systems with equal parameters (except for the number of FH slots). It is also demonstrated that, in some cases, the addition of DS spreading to an FH system, without increasing the total system bandwidth, can significantly improve the system's resistance to partial band multitone jamming. >

Error probability for FH/MDPSK in multitone jamming, fast Rician fading, and Gaussian noise

A method is presented for the calculation of M-ary DPSK error probability in partial-band multitone jamming and white gaussian noise. Both unfaded and faded signals and jamming tones may be analyzed by the method. The fading considered is frequency-flat, time selective, Rician fading. The results have application in mobile, slow frequency-hopped, military, satellite systems. The method uses the Pawula-Rice-Roberts (1982) method for calculating the probability distribution function of the phase angle between two vectors when they are perturbed by noise. The worst case error probability in partial-band jamming with fading is efficiently computed using Houston's (1975) approach. A fundamental parameter, independent of the actual jammer power being used on the system, is identified. The effect of the ratio of the direct signal energy to the faded (indirect) signal energy is shown by example, as is the effect of fading bandwidth and Doppler shift. For practical values of the parameters, jammer fading was not found to be significant. Results for M=2, 4, and 8 are given. >

Analysis of an antijam FH acquisition scheme

An easily implemented matched filter scheme for acquiring hopping code synchronization of incoming frequency-hopping (FH) signals is analyzed, and its performance is evaluated for two types of jamming: partial-band noise jamming and partial-band multitone jamming. The system is designed to reduce jammer-induced false alarms. The system's matched filter output is compared to an adaptive threshold that is derived from a measurement of the number of acquisition channels being jammed. Example performance calculations are given for the frequency coverage of the jamming either fixed over the entire acquisition period or hopped, that is, changed for each acquisition pulse. It is shown that the jammer's optimum strategy (the worst case) is to maximize the false alarm probability without regard for the effect on detection probability, for both partial-band noise and multitone jamming. It is also shown that a significantly lower probability of false acquisition results from using an adaptive matched filter threshold, demonstrating that the strategy studied here is superior to conventional nonadaptive threshold schemes. >

Multitone jamming of hybrid SFH/DS-MFSK communication systems

The performance of hybrid SFH/DS-MFSK systems under partial band multitone jamming is considered. The BER equation derived is appropriate for communication signals consisting of many M-ary symbols per DS code period, jammed by equally-spaced tones with random phase and possibly tone placement errors. This may be used to study the effects of system design alternatives and of jammer tone offsets. Systems with fixed bandwidth and non-overlapping FH channels may be optimised, as can systems with overlapping channels.

The Performance of M-ary FH-DPSK in the Presence of Partial-Band Multitone Jamming

Using a geometric approach, the performance of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -ary FH-DPSK in the presence of partial-band multitone jamming is evaluated. The optimal jamming strategy is determined as a function of the number of signaling levels <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> and the ensuing results are used to determine worst case bit error probability performance as a function of this same parameter. It is demonstrated that, for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> =2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> , the best performance is obtained for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> =4.

Differentially Coherent Detection of QASK for Frequency-Hopping Systems - Part II: Performance in the Presence of Jamming

The performance of differentially coherent detection of frequency-hopped QASK in the presence of partial-band noise and partial-band multitone jamming is presented. In each case, the worst case jamming strategy is determined which consists of specifying the worst case partial-band fraction and the corresponding maximum average error probability. The results obtained are compared with those of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -ary FH-DPSK operating in the same jamming environment.