In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 151, No. 4_Supplement ( 2022-04-01), p. A281-A281
Abstract:
In this paper, we verify the performance of the equalizer and phase-locked loop (PLL) operating jointly for channel time variability in underwater acoustic communications. We apply the decision feedback equalizer in order to eliminate channel multipath and PLL to phase rotation due to Doppler effects. In the PLL, a decision-directed tan−1 type phase detector is adopted. As shown in previous papers, it is difficult to make PLL to be steady state because of time-varying ISI occurred by multipath. Also, the phase rotation incurs the equalizer tap rotation. Therefore, we can see that the two subsystems of equalizer and PLL complement each other perfectly. Another issue is the convergence speed; how quickly we can make the joint equalizer and PLL to be stable state within the preamble period (known data). In order to verify the performance, the sea experiments were conducted in the condition of moving transmitter. The transmitted signal is modulated by using PSK and consists of five burst frames that are composed of preamble of PN code and random data. As a result, if we use the initial multipath value and Doppler frequency offset, we can make the joint equalizer and PLL to be the steady state more quickly.
Type of Medium:
Online Resource
ISSN:
0001-4966
,
1520-8524
Language:
English
Publisher:
Acoustical Society of America (ASA)
Publication Date:
2022
detail.hit.zdb_id:
1461063-2
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