# Design and Signal-Decoding Test Verification of Dual-Channel Round Inductsyn Decoding Circuit
## 4 Experimental and Analysis
### Multisim Simulation Experiment
#### 4.1.2 Induced-Signal Processing Circuit--Multisim Simulation Experiment  
For the simulation experiment of the induced-signal processing circuit, taking the _SIN+_ terminal of the coarse channel as an example, with an an input of 5 mVp-p, 10 kHz sine wave signal as the original induced signal. Additionally, to verify the effectiveness of the filtering circuit, some high-frequency noise is added to the input signal. Simulate the actual state of the original induced signal with noise interference. The parameters of each component in the simulation and the circuit diagram connections are shown in Figure 8.  
Figure 6: Power-amplifier circuit—Multisim simulation circuit.  
Figure 7: Excitation-signal power-amplifier circuit—Multisim simulation waveform.  
In Figure 8, XSC1 is a four-channel oscilloscope, and the waveform recording results of the oscilloscope are shown in Figure 9. XBP2 is a Bode plot tester, and the phase-frequency characteristics curve of the induced-signal processing circuit recorded by XBP2 is shown in Figure 10. The signals and amplitudes corresponding to each channel in Figure 9 are listed in Table 2.  
Figure 8: Induced-signal processing circuit—Multisim simulation circuit.  
Figure 10: Induced-signal amplification and filtering circuit phase–frequency characteristics curve.  
Figure 9: Induced-signal processing circuit—Multisim simulation waveform.  
After adding some noise in the simulation, it can be observed that the waveform of CH1 has more spikes, but the overall sinusoidal characteristic is evident. It is close to the original induced-signal output from the _SIN+_ terminal of the round inductsyn, with an amplitude of approximately 5 mV peak-to-peak and a frequency of around 10 kHz. From the waveform of CH2, it can be seen that after amplification, the original induced signal is at 1.5 V peak-to-peak, and many of the spikes in the waveform have been reduced, although some irregularities still remain.  
As shown in the waveform of CH3, after the signal has passed through filtering, it has become a relatively standard sinusoidal signal. Due to the phase shift caused by the first two stages of the circuit, the waveform in CH3 does not differ significantly in phase from the original induced signal. As shown in Figure 10, the phase-frequency characteristic curve from the Bode plotter in the Multisim software indicates that the phase shift introduced by the two-stage amplification and filtering circuit for a 10 kHz signal is \(-8.826^{\circ}\).  
According previous description, the excitation signal generated by AD2S1210 undergoes an inversion of \(180^{\circ}\) after passing through the power amplifier. When this is combined with the phase shift of the filtering and amplification circuit, and further adjusted by the phase-shift circuit, it can be tuned to achieve a phase difference of within \(44^{\circ}\) compared to the original excitation signal, as shown in the waveform in Figure 9, with an amplitude of 1.6 Vp-p. The simulation results meet the design requirements.