Fig. 1. Schematic diagrams of GM-APD array detection system based on photon counting method.(a) System flow chart; (b) GM-APD array detector received photon coverage distribution diagram; (c) array unit distribution diagram

Fig. 2. Algorithm flow based on time-domain space-domain signal processing. (a) Uniformly distributed signal; (b) Gaussion distribution signal; (c) simulation of the original signal; (d) convolutional layer; (e) activation function; (f) max pooling; (g) fully connected layer

Fig. 3. Matrix dimension expansion calculation method;(a) Raw convolution kernel; (b) row expansion calculation; (c) column expansion calculation; (d) rhombus expansion calculation

Fig. 4. Four-frame echo signal, superimposed signal comparison chart, and log signal-to-noise ratio graph. (a) Single channel reception signal; (b) log signal-to-noise ratio graph; (c) echo signal and frame-by-frame superposition results

Fig. 5. Convolutional kernel processing results for different dimensional expansion methods

Fig. 6. Log signal-to-noise ratio plot for different dimensional expansion methods

Fig. 7. Plots of the results of different standard deviation processing and the change of signal-to-noise ratio