Waveform selection is the key to the performance of active sonar systems, due to the diverse and complementary characteristics of transmitted signals. Among a great quantity of waveforms, a binary phase-shift keyed (BPSK) signal has good Doppler and time resolution properties simultaneously, which makes it advantageous for underwater targets detection.
Under the Doppler perturbation situation, the property of good Doppler resolution will result in a sharp decline in detection performance. In recent years, waveform fusion has got extensive attentions.
A novel waveform combining binary phase-shift keyed signal and a Doppler in sensitive signal can improve the performance of target detection in case of perturbation. This new method has recently been proposed by researchers JIANG LI, YAN Shefeng, WU Yongqing and MA Xiaochuan from the Institute of Acoustics of the Chinese Academy of Sciences.
They have found that a combined linear frequency-modulated binary phase-shift keyed (LFM-BPSK) signal offers stronger performance than a pure binary phase-shift keyed signal under the Doppler perturbation.
There are three sonar transmitted waveforms that have been discussed here i.e. linear frequency-modulated (LFM), binary phase-shift keyed (BPSK), and linear frequency-modulated binary phase-shift keyed (LFM-BPSK). Each has unique characteristics that may be exploited to advantage in particular situations.
The binary phase-shift keyed has good time and Doppler resolution, however, the detection performance will sharply decline under the perturbation situation. Meanwhile, if one desires the good time and Doppler resolution like binary phase-shift keyed signal, linear frequency-modulated binary phase-shift keyed waveform is a solution.
The time and Doppler resolution of linear frequency-modulated binary phase-shift keyed signal will decline compared with binary phase-shift keyed signal. Still the match filter loss of linear frequency-modulated binary phase-shift keyed doesn’t decline as that. Thus it can be said the linear frequency-modulated binary phase-shift keyed waveform is a compromise solution.
Future research is to be carried out on a lake trial, where the detection performance analysis of the linear frequency-modulated binary phase-shift keyed under the influence of underwater channel will be paid more attention to.
Reference：
JIANG LI, YAN Shefeng, WU Yongqing and MA Xiaochuan. Sonar Detection Performance with LFM-BPSK Combined Waveforms. OCEANS 2016- Shanghai. DOI: 10.1109/OCEANSAP.2016.7485501
Contact:
YAN Shefeng
Institute of Acoustics, Chinese Academy of Sciences, 100190 Beijing, China
Email: sfyan@ieee.org