What kind of transmission characteristics should the ideal bandpass filter have?

Depus Electric will answer for you: 1. Filter out current harmonics, which can efficiently filter out the harmonics of 2 25 times in the load current, so as to make the distribution network clean and efficient, and meet the requirements of the national standard for distribution network harmonics. The product truly achieves adaptive tracking compensation, which can automatically identify the overall change of load and the change of load harmonic content and quickly track the compensation, 80us response to load change, 20ms to achieve complete tracking compensation.

2. Improve the system imbalance, which can completely eliminate the system imbalance caused by harmonics, and in the case of equipment capacity, the negative sequence and zero sequence unbalance components of the system can be compensated according to the user's settings and the reactive power can be appropriately compensated. On the basis of ensuring the function of filtering out harmonics, the system imbalance is effectively improved. 3. Suppress the resonance of the power grid, and will not resonate with the power grid, and in its capacity

If a channel has a uniform bilateral noise power spectral density, an amplitude modulated signal is transmitted in the channel, and the frequency band of the modulated signal is limited to 5, and the carrier frequency is 100, the sideband power is 10, and the carrier power is 40, if the receiver gets the input signal through a suitable ideal bandpass filter, and then added to the envelope detector for demodulation. Try to find: (1) the signal-to-noise power ratio at the input end of the demodulator;

2) the signal-to-noise power ratio at the output of the demodulator;

3) Institutional gains.

The former is called an "infinite gain multiplex feedback" band-pass filter, and the latter is called a "voltage-controlled voltage source" band-pass filter, both of which are very common forms of active filters that can be designed to achieve the same performance.

The former can use one less component, but when the value of the element is high, the numerical range of the component is widely distributed, and the error of the component has a great influence on the value of the Q, so it is best to use it below Q 10; The bandwidth and center frequency of the latter can be adjusted separately, which is more convenient to adjust, and the Q value should not be greater than 10.

A filter that allows only a certain frequency to pass through is called a bandpass filter.

The center frequency and bandwidth of the bandpass filter are dedicated to the frequency sweeper, the signal generator, and the millivoltmeter. The display of the dedicated scanner is relatively straightforward, you can see its instructions.

You can also use the signal generator as the input signal input filter, the output terminal uses a millivoltmeter to measure the output voltage, change the output frequency of the signal generator, the output voltage will change, the corresponding signal generator frequency when the output voltage is the maximum is the center frequency of the filter, on both sides of the center frequency, the difference between the two frequencies corresponding to the amplitude change to the output maximum value is the pass band.

The conditions for this cluster closure are as follows:1. According to today's headlines, the center frequency must fall within the passband range of the bandpass filter, and the center frequency must match the band-through width and order of the filter to obtain the best filtering effect.

2. The center frequency should select the most important frequency in the signal to ensure that the key information of the signal is not filtered out.

The center frequency is usually defined as the geometric mean of the bandpass filter frequency, which in logarithmic coordinates is the midpoint between two 3dB points, and is generally represented by the arithmetic average of two 3dB points. The frequency in the middle of the passband of the filter is subject to the center frequency, which is higher than the center frequency until the frequency voltage decays to multiple times is the upper side frequency, and the opposite is the lower side frequency, and the pass band is between the upper and lower edge frequencies.

In a digital baseband signal transmission system, the transmit filter can play the role of ().

a.Filter out channel out-of-band noise.

b.Pattern transformation of the input transmission code.

c.The frequency band in which the input signal is compressed.

d.Converts the waveform of the transmission code entered by Kiri.

e.Generate bit-timed synchronization pulses.

Correct Answer: Perform a pattern transformation on the input transmission code; The frequency band of the input signal is reduced by the pressure wheel.; Converts the waveform of the input transmission code.

Summary. Kiss, I'm here for you. Low-pass:

Low-pass filter is an electronic filter device that allows signals below the cut-off frequency to pass through, but signals above the cut-off frequency cannot pass through. Qualcomm: It is a combination device of capacitors, inductors, resistors, and other devices that allow signal components above a certain frequency to pass through and greatly suppress signal components below this frequency.

Its characteristics can be described in terms of impulse response and frequency response in the time and frequency domains, respectively. Let's say a sensor with a sampling frequency of 500Hz. When the waveform is collected to dry, it is found that there are (400Hz, 30Hz, 50Hz, 15Hz, 10Hz).

Low-pass filter: pass below 30Hz, 30Hz

What are the conditions for the frequency characteristic function of ideal filters such as low-pass and high-pass in their respective pass bands?

Kiss, I'm here for you. Low-pass filter is an electronic filter device that allows signals below the cut-off frequency to pass through, but signals above the cut-off frequency cannot pass through.

Qualcomm: It is a combination device that allows the signal components of the nuclear source above a certain frequency to pass through, and greatly suppresses the signal components below the frequency. Its characteristics can be described in the time domain modification and frequency domain by impulse response and frequency response, respectively.

Let's say a sensor with a sampling frequency of 500Hz. When the waveform is collected to dry, it is found that there are (400Hz, 30Hz, 50Hz, 15Hz, 10Hz). Low-pass filter with you:

Passes below 30Hz, 30Hz

Types of Qualcomm: 1. Active high-pass filters and passive high-pass filters are classified according to the different devices used. Passive high-pass filter:

A filter consisting only of passive components (R, L, and C) is constructed using the principle that the reactance of capacitor and inductive elements changes with frequency. The advantages of this type of filter are: the circuit is simpler than the leakage, does not require DC power supply, and has high reliability; The disadvantages are:

The signal in the passband has energy loss, the loading effect is more obvious, and it is easy to cause electromagnetic induction when using inductive elements, and the volume and weight of the filter are relatively large when the inductance l is large, and it is not suitable in the low frequency domain. Active high-pass filter: It consists of passive components (typically R and C) and active components (such as integrated operational amplifiers).

The advantages of this type of filter are that the signal in the passband not only has no energy loss, but can also be amplified, the load effect is not obvious, and the interaction between multiple stages is very small. It is easy to form a high-order filter using the simple method of cascade, and the filter is small, lightweight, and does not require magnetic shielding (since no inductive components are used); The disadvantages are:

The passband range is limited by the bandwidth of active devices (such as integrated operational amplifiers), which requires DC power supply, and the reliability is not as high as that of passive filters, and is not suitable for high-voltage, high-frequency, and high-power occasions. 2. According to the mathematical characteristics of the filter, it is divided into first-order high-pass filter, second-order high-pass filter, etc.

The passband cut-off frequency of the low-brightness guess-pass filter must be lower than the passband cut-off quiet frequency of the high-pass filter.

a.That's right. b.Mistake.

Correct answer: B