The working principle of the phase sensitive detection circuit is briefly described

Multiply the modulated signal UX by the carrier signal with an amplitude of 1 to obtain the bilateral band amplitude modulation signal us, and multiply the bilateral band amplitude modulation signal us by the carrier signal, and the modulated signal UX can be obtained after low-pass filtering. This is the reason why phase-sensitive detection circuits are structurally similar to modulation circuits.

If the electric field meter probe is in a positive electric field, the induced voltage signal and synchronization signal of the probe are input through the geophone, respectively.

Multiply the modulated signal UX by the amplitude.

The carrier signal of 1 can obtain the bilateral amplitude modulation signal us, and the bilateral amplitude modulation signal us is multiplied by the carrier signal, and the modulated signal UX can be obtained after low-pass filtering.

The phase-sensitive detector realizes the multiplication of the high-frequency amplitude modulation signal and the high-frequency carrier signal, and outputs the low-frequency demodulation signal after filtering.

The phase-sensitive detection circuit is the phase detection circuit, when the signal phase is deviated from the phase of the standard signal source, the circuit is detected, and there is a strong and weak output according to the size of the deviation, so as to control other circuits.

The phase-sensitive detector eliminates the influence of higher harmonics, so that the amplitude of the output signal is proportional to the amplitude of the carrier signal, so that the amplitude modulated signal can be demodulated and reproduced.

Through a low-pass filter.

After the output of a negative polarity DC voltage signal, the measured electric field can be judged as a negative electric field, so as to achieve the accurate identification of the polarity of the measured electric field.

Analog PSD: Using a multiplier, a reference signal with the same frequency as the signal to be measured is multiplied by the signal to be measured, and the result is a DC signal related to the amplitude and phase of the signal to be measured through a low-pass filter.

Digital PSD: The synchronous rectification circuit is controlled by a reference signal with the same frequency as the signal to be measured, and the synchronous rectification result of the signal to be tested is obtained through a low-pass filter to obtain a DC signal related to the amplitude and phase of the signal to be measured.

1. The conditions of use are different.

When the synchronous detection circuit detects the wave, it is necessary to add a synchronous signal at the same frequency and in phase as the amplitude modulation signal.

Envelope detection. There is no need to add a synchronization signal.

2. The scope of application is different.

Synchronous detection circuits can be used to demodulate any amplitude modulation wave, but in order to obtain a synchronous signal at the same frequency and in phase as the amplitude modulated signal, the circuit is more complicated, so it is mainly used to demodulate unilateral sideband and bilateral amplitude modulation signals.

The envelope detection of the hidden wave of the electric touch hall is very simple, but it is only suitable for demodulating ordinary amplitude modulation waves.

Hello, phase-sensitive detection circuit and normal detection circuit are two different circuits. A phase-sensitive detection circuit is a circuit that uses phase difference detection technology to achieve high-speed and high-sensitivity detection. There is a phase difference between the input signal and the reference signal of the phase-sensitive detection fast trap circuit, and the amplitude information of the input signal can be obtained by measuring the phase difference.

The advantage of the phase-sensitive detection circuit is that it can achieve high-speed, high-precision signal detection, and is suitable for signal detection with high frequency. The ordinary detection circuit is a simple signal detection circuit, by filtering out the high-frequency part of the input signal, only retaining its low-frequency part, and then rectifying and smoothing to obtain a DC voltage related to the amplitude of the input signal. The advantages of ordinary detection circuit are simple and easy to implement, and it is suitable for detection with low signal frequency and low accuracy requirements.

In general, the phase-sensitive detection circuit is suitable for high-speed, high-precision signal detection, while the ordinary detection circuit is suitable for detection with low signal frequency and low sideslip accuracy requirements. It is necessary to select the appropriate circuit according to the specific application scenario.

The main difference between phase-sensitive detection circuits and ordinary detection circuits is that they use different detection components. Ordinary detection circuits generally use passive components such as half-wave rectifiers, full-wave rectifiers or constant-voltage diodes for detection, and their principle is to convert the input AC signal into DC signal output. This method has low detection efficiency, and has problems such as reverse leakage current and capacitive filtering.

The phase-sensitive detection circuit uses active components such as operational amplifiers and limiting amplifiers as detectors, and uses nonlinear characteristics to detect and demodulate the input signal. The phase-sensitive detection electrocollapsing circuit has the advantages of high efficiency, fast response, low distortion, etc., and is suitable for detection and demodulation in complex environments such as high frequency and weak signals. In short, the phase-sensitive detection circuit is more sensitive and efficient than the ordinary detection posture annihilation circular circuit, and is suitable for signal detection and demodulation in complex environments.

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Summary. Both phase-sensitive detection circuits and ordinary detection circuits are circuits used to detect information signals in modulated signals, but their working principles are different.

Both phase-sensitive detection circuits and ordinary detection circuits are circuits used to detect information signals in modulated signals, but their working principles are different.

Ordinary detector circuits use the nonlinear characteristics of diodes and other devices to convert the amplitude change of the modulated signal into a DC signal output. Simple amplitude modulation (AM) signal detection can be achieved. Conversely, this principle can also be used to transport the group to achieve the side-by-orange demodulation of the modulated signal.

This kind of circuit is often used in the detection of low-frequency modulated signals.

The phase-sensitive detection circuit compares the phase of the modulated signal with the reference signal, and outputs a pulse or DC car mode voltage when the phase difference is zero. The phase-sensitive detection circuit can detect the modulated signal with higher sensitivity, and it is also effective for the detection of phase modulated (FM) signals and frequency modulated (PM) signals. Therefore, in the detection of high-frequency modulated signals, phase-sensitive detection circuits are often used.

In general, phase-sensitive detection circuits and ordinary detection circuits have their own advantages and disadvantages, and the specific choice of which circuit should be judged according to the specific situation. If it is necessary to detect signals with high frequency random clearing and modulation mode of FM or PM, the phase-sensitive detection circuit is used in a closed manner; If you only need simple amplitude modulation signal detection, you can use a common detection circuit.

First of all, let's introduce phase-sensitive detection: phase-sensitive detection circuit is a detection circuit with the ability to distinguish the phase of the modulated signal and select the frequency.

Principle: The phase-sensitive detection circuit (with the filter) can restore the amplitude modulation wave to the original signal waveform and play a demodulation role; and has the ability to identify the phase of the signal. A typical diode phase-sensitive detection circuit and its input-output diagram are shown below. by four.

The diode D1 D4 with the same characteristics is connected in series along the same direction into a bridge loop, and there is an additional resistor on the bridge arm, which is used for the four endpoints of the bridge scale to be connected to the secondary coils of transformer A and B respectively, the input of transformer A is the amplitude modulation wave XM(T), and the input signal of B is the carrier Y(T), UF

The frequency selection characteristics of the phase-sensitive detection circuit refer to the fact that it has different transmission characteristics for input signals of different frequencies. With the reference signal as the fundamental wave, all even harmonics have an average output of zero in one cycle of the carrier signal, that is, it has the function of suppressing even harmonics. For n=1, 3, 5 and other odd harmonics, the amplitude of the output signal is attenuated to 1 n of the fundamental wave, that is, the transmission coefficient of the signal decreases with the increase of harmonic times, which has a certain suppression effect on the higher harmonics.