I forgot all the math.

呜呼哀哉

I forgot all the math. [Copy link]

 

For the normalized n-order low-pass filter, it can be considered that

Actually, this is with phase. Now how to find the modulus expression? I forgot the phase angle expression.

I haven’t returned my math knowledge to the teacher yet. Please help me, friends.

极限零

I forgot too, now I'll just use the code to calculate it...

Squat with a great god

okhxyyo

I dare not answer because I have already given it to the teacher.

wangerxian

I have been working for a few years and have hardly used any mathematical formulas. . .

lkh747566933

I have graduated for many years and I have almost forgotten all the math I learned in high school, let alone something this difficult.

呜呼哀哉

It seems that I am not the only one who has given back the knowledge to the teacher. Everyone is almost the same. As a result, I found it and roughly estimated it, which is correct, but I can't calculate it, and I can't do the modulus value of a+jb.

秦天qintian0303

a little complicated

呜呼哀哉

Qintianqintian0303 posted on 2023-9-1 09:32 A bit complicated

Moderator, how do you calculate the modulus of a+jb? It should be the square root of a plus the square of b, right? And the phase angle should be the inverse tangent of B/A?

秦天qintian0303

Alas, posted on 2023-9-1 11:06 Moderator, how do you calculate the modulus of a+jb? It is the square root of a plus the square of b, right? The phase angle is the inverse tangent of B/A?

Mathematics is returned to school.

吾妻思萌

For an N-order low-pass filter, the normalized phase angle formula is:

Ark = tan-1(w*N)

here,

• Ark is the normalized phase angle,
• w is the frequency,
• N is the order of the filter.

This formula is valid for Butterworth filters. For other types of low-pass filters, such as Chebyshev or elliptic functions, the phase angle formula will be different.

Note: In actual applications, due to errors in resistance, capacitance, and external factors such as power supply, the phase angle formula may deviate from the theoretical value.

chejm

I totally agree. After working for a few years, you will find that what you learned in school is basically useless.

振动试验仪器

The knowledge learned in school is to lay the foundation, focusing on theory, and is seriously out of touch with actual work, so I don’t feel the usefulness of knowledge in my work. The biggest shortcoming of education is to instill knowledge into students, but not teach them how to use it.

振动试验仪器

In school, we learn to solve problems and calculate fractions in math class, but in actual work, I think the role of math is the application of mathematical ideas and methods.

天地侠客

Alas, posted on 2023-9-1 11:06 Moderator, how do you calculate the modulus of a+jb? It is the square root of a plus the square of b, right? The phase angle is the inverse tangent of B/A?

right

天地侠客

Vibration Test Instrument Published on 2024-1-8 16:24 The knowledge learned in school is to lay the foundation, focusing on theory, and is seriously out of touch with actual work, so I can't feel the usefulness of knowledge in my work. The greatest benefit of education...

Brother, how do you think students should learn? I feel like I have learned a lot of theory, but I don’t know how to apply it.

呜呼哀哉

Tian Di Xia Ke posted on 2024-1-26 14:37 Brother, how do you think students should learn? I feel like I have learned a lot of theories, but I don’t know how to apply them

It's so good to be a student in school. If you want to work on software, you only need a computer and an embedded application development board. But the hardware is a bit miserable. It is difficult to implement a design without a purpose. If you are good at theory, you can watch the college students' electrical competition. A teacher in the forum gave a very good analysis and explanation. You can choose a topic, find out the software design principle and PCB, and you will be quite familiar with it after soldering and debugging it yourself once.

gmchen

Strictly speaking, the low-pass filter formula on the first floor is wrong.

The 8th floor gives the calculation formula for the modulus of complex numbers.

The 10th floor gave a normalized phase angle formula. The normalization here means that the angular frequency w in this formula is normalized, that is, the cutoff angular frequency of the filter is equal to 1. The 10th floor pointed out that this formula is only applicable to Butterworth filters, which is indeed the case.