Fig.1

Multibeam echosounder system"

Fig.2

Signal processing flow of multi-beam sounding system"

Fig.3

Schematic diagram of phase detection method"

Fig.4

Schematic of channel coherence"

Fig.5

Variation curve of coherence factor characteristics with respect to array element number and selection method"

Fig.6

Block diagram of fitting interval estimation method"

Fig.7

Diagram of the single Ping water body in sea area 1"

Fig.8

Diagram of the subarray correlation coefficient for the single Ping in sea area 1"

Fig.9

Single Ping sounding results by correlation coefficient method in sea area 1"

Fig.10

Phase difference curve of 5th beam by correlation coefficient method"

Fig.11

Diagram of the channel coherence factor for the single Ping in sea area 1"

Fig.12

Phase difference curve of the 5th beam by coherence factor method"

Fig.13

Single Ping sounding results by coherence factor method in sea area 1"

Fig.14

Seabed topographic maps of sea area 1"

Fig.15

Diagram of the single Ping water body in sea area 2"

Fig.16

Diagram of correlation coefficient of single Ping subarray in sea area 2"

Fig.17

Local map of subarray correlation coefficient in sea area 2 （$ \eta = 0.4 $）"

Fig.18

Phase difference curve of the 32nd beam by correlation coefficient method （$ \eta = 0.4 $）"

Fig.19

Single Ping sounding results by correlation coefficient method in sea area 2 （$ \eta = 0.05 $）"

Fig.20

Single Ping sounding results by correlation coefficient method in sea area 2 （$\eta = 0.4$）"

Fig.21

Diagram of channel coherence factor of single Ping in sea area 2"

Fig.22

Phase difference curve of the 32th beam by coherence factor method"

Fig.23

Single Ping sounding results by coherence factor method in sea area 2"

Fig.24

Post processing results in sea area 2"