wifiが切れる・マウス反応悪い｜USB 3はノイズを出す
USB 3.0* Radio Frequency Interference Impact on 2.4 GHz Wireless Devices
by intel April 2012
2.4 GHz Wireless Devices
The 2.4 GHz ISM band is a widely used unlicensed radio frequency band for devices
such as wireless routers, as well as wireless PC peripherals such as a mouse or
keyboard. These devices may use standard protocols such as the IEEE 802.11b/g/n or
Bluetooth, or they may use proprietary protocols. The radios may use frequency
hopping, frequency agility, or may operate on a fixed frequency.USB 3.0*USB 3.0 or SuperSpeed USB* has a 5 Gbit/s signaling rate. The USB 3.0 specification
requires USB 3.0 data to be scrambled and it requires spread spectrum to be applied
on the clock. The data spectrum can be modeled as a ‘sinc’ function
the data spectrum is very broadband, ranging from DC to
5 GHz. Figure 2-2 shows the data spectrum measured by directly probing one of the
USB 3.0 transmit-pair signals of a notebook computer.
USB3に接続されているものから漏れる
A near field probe was placed close to an external USB 3.0 hard disk drive (HDD) in an
RF absorber chamber and a noise measurement was made using a spectrum analyzer,
with and without the HDD connected. The results are shown in Figure 3-3. With the
HDD connected, the noise floor in the 2.4 GHz band is raised by nearly 20 dB. This
could impact wireless device sensitivity significantly.
マウスレシーバの位置で比較
USB3はシールドに神経を使うように。
安いusb3.0ケーブルはシールドがされていない部分がありノイズが漏れるものがある。
usb３に接続されている貧相なケーブルはノイズ放出元（アンテナ）になる
usb3に接続されているケーブルを一度外して比べてみる。
廉価なUSB3.0ハブ は危険
※USB2.0は無問題 周波数低い
USB2.0ケーブルは信号経路が違う、3.0と接続していない。
廉価なLED照明もノイズを出す
消して比較してみましょう。
*正確な情報を記載するよう努めておりますが、その完全性・最新性・正確性について保証するものではありません。
