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phase with the corresponding sequences of the transducer selected (see figure 3). The output of both correlations is added and an ideal delta is obtained. The peak of the obtained delta will correspond to the received echo.

Figure 3 phase with the corresponding sequences of the transducer selected (see figure 3). The output of both correlations is added and an ideal delta is obtained. The peak of the obtained delta will correspond to the received echo.

Related Figures (8)

For simplification in the correlation algorithm, it is also assumed the received signal to be the same attenuated emitted one plus an additive gaussian noise [13]. It is assumed a 2,5Us period (400KHz sampling rate), so we will have eight samples per received QPSK cycle. Figure 2 shows a transmitted sequence generated using the complementary pair {A=1001010001, B=1000000110}.
For simplification in the correlation algorithm, it is also assumed the received signal to be the same attenuated emitted one plus an additive gaussian noise [13]. It is assumed a 2,5Us period (400KHz sampling rate), so we will have eight samples per received QPSK cycle. Figure 2 shows a transmitted sequence generated using the complementary pair {A=1001010001, B=1000000110}.
Once each phase is demodulated and low pass filtered, the received I and Q sequences are obtained (see figure 2), and an independent correlation is performed on each
Once each phase is demodulated and low pass filtered, the received I and Q sequences are obtained (see figure 2), and an independent correlation is performed on each
Figures 5 shows de emitted and received signals. Figure 6 shows the received phases and the correlation obtained for both transducers with the configuration showed in figure 7. Displacements in the microphone position with respect to transducers can be detected by means of the location of autocorrelation peaks as it is shown in the figure 6, where it is easy to appreciate the differences between
Figures 5 shows de emitted and received signals. Figure 6 shows the received phases and the correlation obtained for both transducers with the configuration showed in figure 7. Displacements in the microphone position with respect to transducers can be detected by means of the location of autocorrelation peaks as it is shown in the figure 6, where it is easy to appreciate the differences between
signal is simulated without noise, as we only want to know the influence of crosscorrelation due to the simultaneous reception.
signal is simulated without noise, as we only want to know the influence of crosscorrelation due to the simultaneous reception.
both TOF denoting the light displacement from the axial axis. Obviously non-zero crosscorrelation between sequences yield to non-ideal signals but peaks maintain
both TOF denoting the light displacement from the axial axis. Obviously non-zero crosscorrelation between sequences yield to non-ideal signals but peaks maintain
At last, figure 10 shows the practical result for a two simultaneously received transducers signals as it was done in figure 6. In real system, different peak level values are due to amplifier gain. To verify theoretic results, a _ relatively simple configuration is set up (figure 8). An HC11 family microcontroller based card is used to generate up to four synchronous low correlated QPSK modulated signals, this signals are fed to a power stage and then to four 50Khz Polaroid transducers.
At last, figure 10 shows the practical result for a two simultaneously received transducers signals as it was done in figure 6. In real system, different peak level values are due to amplifier gain. To verify theoretic results, a _ relatively simple configuration is set up (figure 8). An HC11 family microcontroller based card is used to generate up to four synchronous low correlated QPSK modulated signals, this signals are fed to a power stage and then to four 50Khz Polaroid transducers.
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