What is phase sensitive demodulator?
Phase-sensitive demodulation PSD is important for sig- nal conditioning in electronic instrument design and for communication. Its output is a function of not only the amplitudes of both input signals but also the phase difference between the two input signals.
What is the function of phase sensitive detector in a LVDT circuit?
A phase sensitive detector (PSD) is a useful circuit to make the measurement direction sensitive. It is connected at the output of the LVDT and compares the phase of the secondary output with the primary signal to judge the direction of movement.
What is LVDT sensitivity?
Sensitivity is usually specified in terms of milliVolt output per thousandths of an inch core displacement per Volt of excitation (mV/mil/Volt). Sensitivity varies with excitation frequency, which must also be specified. Sensitivity mostly affects the gain required of the LVDT’s signal conditioning electronics.
What is LVDT signal conditioner?
The model LVDT/A or LVDT/D signal conditioner provides a convenient and flexible solution to the measurement of displacement or position (linear or angular) when using Linear Variable Differential Transformers or Rotary Variable Differential Transformers (LVDT’s or RVDT’s).
What is phase sensitivity?
adjective. Sensitive to the phase of a vibration, current, etc.; (of a detector or other device) producing an output that is proportional to the phase difference between an input and a reference signal.
What is phase sensitive detection?
Phase sensitive detection is a method whereby the signal of interest is “tagged” by modulating at a frequency much higher than any normal changes which the signal might experience. This tagged signal is then later retrieved amidst the unwanted noise.
What is null position in LVDT?
The zero, called Null Position, is defined as the core position where the phase shift of the (Va-Vb) differential output is 90 degrees. LVDT Schematic. The differential output between the two secondary outputs (Va-Vb) when the core is at null position is called the Null Voltage.
What is principle of operation of LVDT?
The working principle of the linear variable differential transformer or LVDT working theory is mutual induction. The dislocation is nonelectrical energy that is changed into electrical energy. And, how the energy is altered is discussed in detail in the working of an LVDT.
How do you find the sensitivity of LVDT?
To determine the sensitivity, we energize the primary at the recommended drive level (3 VRMS for E-100 LVDT) and move the core off the null position by the full-scale displacement. Now, we measure the voltages across the two secondary windings to find the overall output voltage (Vout).
What is sensitivity and resolution?
RESOLUTION – the smallest portion of the signal that can be observed. SENSITIVITY – the smallest change in the signal that can be detected.
What is meant by signal conditioner?
Signal conditioning is the manipulation of a signal in a way that prepares it for the next stage of processing. Many applications involve environmental or structural measurement, such as temperature and vibration, from sensors.
What is the working principle of LVDT?
LVDT works under the principle of mutual induction, and the displacement which is a non-electrical energy is converted into an electrical energy. And the way how the energy is getting converted is described in working of LVDT in a detailed manner.
How does synchronous demodulation of LVDT multiplies differential output?
The synchronous demodulation technique multiplies the LVDT differential output by the excitation signal (or a signal synchronous with the excitation signal in general). This gives: Equation 2. The first term inside the brackets is DC, however, the second term is at twice the excitation frequency.
Can a rectifier demodulator be used on a 5 wire LVDT?
With a rectifier-type demodulator, we need access to the center tap of the LVDT secondary to rectify the voltage across each of the secondary windings. Therefore, this type of demodulation is only applicable to 5-wire LVDTs (Figure 1 (b)).
What is the required current for a LVDT?
A: It is almost always a low-distortion, constant-amplitude sine wave typically between 1 kHz and 20 kHz. The amplitude is usually between 1 and 24 Vrms, and the required current is between 20 and 100 mA, depending on the LVDT specifics. The classic Wein-bridge oscillator architecture is often used due to its simplicity and low distortion.
What is the function of a demodulator in a signal conditioning circuit?
A: The function of the demodulator is to take the AC output of the transducer and convert it into a useful dc voltage proportional to displacement, Figure 2. In a basic signal-conditioning circuit, the absolute values of the two output voltages of the secondary outputs are subtracted.