Band Pass Filter

You know nature is analog while electronics systems accept only digital.
The systems need the A-D converter to deal with analog on digital system.

The sound is known as the wave which is the analog.
When the system computes the sound, the sound wave must pass through the filter.
Filter allows only the wave with the certain frequency passes through.

The BPF is the filter witch has the characteristics of both the LPF and the HPF.
There are several types of the BPF; negative feedback makes the circuit more stable.

As the example, one of the BPF is shown below.



You may check the behavior of this filter on the LTspice or the PSPICE. :)

Kawasaki.F vs. Kashima.A

Last week, J league had experienced one of the game (Kawasaki vs Kashima) was canceled due to the heavy rain despite in the 2nd half. And yesterday, J league has concluded the game will restart
since 29 min. of the 2nd half with the score, 3-1; Yahoo! Japan informed it. Many people placed their comments on the article. According to the comments, most people blamed the referee for the fact that he decided to cancel the game.

What I want to say them is you cannot say anything if you are not a referee! I'm sure they can't do even good call on the game. The judging is so tough, and has to be neither subjective nor objective. I used to be a referee, I know how tough it is. And I can see why he did so.


先週、Jリーグの鹿島vs川崎Fのカードが豪雨のため、後半途中で中止となりました。この件に関してJリーグは後半２９分からの後日試合再開を決定しました。YahooJapanのスポーツ欄に掲載されてました。この記事には多数のコメントが寄せられており、その多くが主審に対する不満でした。

当事者でない人がそんなに上から目線で平気で発言していることには正直驚きます。彼らが審判をやってもひどい判定しかできないと思いますが。そもそも判定はとても難しく、その場その場で基準が多少変わります。僕は審判員をやっていたことがあるのでわかりますし、その審判員の判定も正しいと思います。

test 1 week!

In colleges in the US, there are not "exam week" for mid-term exams in Japan. Each class has own exams in class and arranges the individual dates for them, and we usually have 3 tests and 1 final; these tests share at least 40% of the final grade on the class.

Ooo, I have 2 tests tomorrow.... study, study hard....


アメリカの大学では日本でいう中間試験のようなテスト週間はありません。各授業で授業時間内にテストを受け、その日も授業によって様々で、通常３つのテストと１つの期末があります。これらはだいたい最終成績の４０％以上を絞めます。

明日はテストが２つもあって。。。。大変なのです。