h********e
发帖数: 1130 | 1 Sorry can't type Chinese in this computer.
Here is recording link (noise start at 1:25) https://soundcloud.com/hiac-
banks/noise-1-25
Last year I got into an accident, and my primary car is total, so I started
to drive this backup car, a 2002 Honda civic. life is a little bit messy
after the accident, spent a lot of time on the medical/billing, and paid
little attention to this old car until today.
since about 4 months ago, I notice the car is slow to start. Every day I
drove about 0.25 mile in ... 阅读全帖 |
|
w*******y
发帖数: 60932 | 2 Audio-Technica ATH-ANC23 QuietPoint Active Noise-Cancelling In-Ear
Headphones $38.95 at buydig.com when you apply coupon code "SOUNDON5" in the
cart
ATH-ANC23 QuietPoint Active Noise-Cancelling In-Ear Headphones reduce
distracting background noise by up to 90% while offering the superior sound
that makes Audio-Technica a world-leading pro audio company.
Engineered to create a comfortable listening environment in areas with high
ambient noise, these in-ear headphones feature a miniature microphon... 阅读全帖 |
|
b*****e
发帖数: 1193 | 3 我的看法
１）white noise是如何产生的？所有的电路都会产生吗white noise？
white noise是随机噪声，没有特定的统计规律的噪声；所有电路元件的噪声叠加在输
出端，可以看作白噪声；做仿真时我用gaussian noise作为white noise的近似
２）如何确定采集的数据中有white noise？
作FFT，可看见频谱很宽的噪声
无法通过带通/阻filter有效去除。
３）如何消除white noise？能推荐几个算法吗？
Adaptive filter
adaptive median filter
wiener filter
另外观察噪声的幅值和相位特征，也是一个很直观的滤波的办法 |
|
ET
发帖数: 10701 | 4 想了半天，终于明白了你这个问题了。
你的意思是说，flicker noise的corner frequncy ，在经过一个single ended amplif
ier (2-pole filter),这个corner frequency 会会被spread out?
这个flicker noise的noise corner是基于noise density.
而经过一个single-ended amplifier后（two-pole), 算出的noise是total noise. 这时
的bandwith是这个filter的bw.
我认为不是一个概念。
but
for
noise |
|
m*****t
发帖数: 3477 | 5 That's the point.
One student from Berkely simulate output noise using our model and complain
the "noise corner frquency"(where the slop turn to flat) is too high.
I believe he mistaked the input noise corner (KHz) with the output noise
spectrum.
He/She should simulate input refeerd noise, where you set Vd as noise source
and prob the noise at G. I want to confirm that. |
|
X***9
发帖数: 7385 | 6
Active Noise Cancellation (ANC)
并非全系都有，以前只有6缸的有，为了减少3缸工作时候带来的噪音（引擎缸数越少噪
音越大。
现在的雅阁是全系都有，但本田一贯低调的态度所以并不刻意宣传自己，所以不是很多
人都知道
拥有新款雅阁的同学可以回家看看自己车子的顶棚，除了前方有个蓝牙的麦克风外，后
排顶上还有一个麦克风
Active Noise Cancellation (ANC) is designed to dramatically reduce low
frequency noise in the interior. The system operates whenever the car is
running, regardless of whether the audio system is on or off.
The microphones capture low-end drivetrain frequencies entering the cabin,
and send a signal to the Active Noise Cancellat... 阅读全帖 |
|
t*******h
发帖数: 2744 | 7 Beatdom
ABOUTSUBMISSION GUIDELINESBUY
Home/Beatdom Content/Noise Poetry: An Interview with Thurston Moore
Thurston Moore reading his poetry at Naropa University's Summer Writing
Program, 2011.
Noise Poetry: An Interview with Thurston Moore
Share
0
0
0
As an MFA fiction student at the Jack Kerouac School of Disembodied Poetics
at Naropa University (one of the longest, most consistently-made-fun-of
school names ever), I was fortunate enough to be brought face-to-face with
some of the most legendar... 阅读全帖 |
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p***p
发帖数: 16 | 8 Noise figure (NF) is defined as the ratio of input SNR (signal to noise ratio)
and output SNR. Because the a sistem (no matter it's an amplifier or sth else)
generate noise itself, input SNR is always greater than output SNR. Therefore,
NF is alway bigger than 1.
NF is related to noise temperature (Tn) by: NF=Tn/293+1. Tn can be measured
using Y factor method. Use two noise sources: hot source at high temperature
(Th), and cold source at low temperature (Tl). And measure the output noise
power. |
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H****E
发帖数: 444 | 9 model card里边flicker noise的参数KF, AF, EF都已经设定好了，noise应该是由
MOS器件本身产生的(flicker+thermal)但是在icfb的noise analysis下，需要选择
output noise和input noise，我应该如何选呢，请熟悉noise analysis的大哥大
姐们指点一下，谢谢！ |
|
h********t
发帖数: 555 | 10 you are right. in reality, most noise energy is below fs/2, but there are
still some noise energy beyond fs/2. from design aspect, it is a good
assumption that all noise energy is below fs/2,so that you can be prepared
for the worst case. for high resolution A-D converters, the noise
performance actually is limited by thermal noise, not Q-noise.
to
independent |
|
ET
发帖数: 10701 | 11 啥technology node?
现在的65nm 45nm flicker noise corner 上MHz也完全现实的。
input referred noise的唯一物理意义是可比性，无法可测。
都是通过测量output noise density, 折算回去。 在simulation中，
也不要设定noise souce, 因为transistor本身就是个noise source, 要measure的就是
ouput noise density..
complain
source |
|
m*******1
发帖数: 13 | 12 I think it may be related to noise parameters of a LNA. The noise figure
depends on the noise parameters and the source reflection coefficient.
F=F_{min}+\frac{4R_n|\Gamma_S-\Gamma_{opt}|^2}{Z_0|1+\Gamma_{opt}|^2(1-|\
Gamma_S|^2)}
F_{min}, R_n, and \Gamma_{opt} are the 4 noise parameters of an amplifier.
Basically, the output noise figure varies as the input is terminated by
different impedances. And \Gamma_{opt} is usually designed to be close to
perfect match, ~0. So I bet you measured lower n... 阅读全帖 |
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k***s
发帖数: 14 | 13 Hello everyone,
My house is close to Catamaran Park. It is not directly under the airflight
path, but can still hear quite a bit airplane noise from rooms facing the
northeast direction. Half of the windows are single pane and the other half
are double pane.
Does installing double pane windows reduce noise level? I heard the
airplane noise are low frequency noise and double pane window may not help
for this type of noise.
How do you deal with airplane noise in FC?
thanks in advance,
Kanas |
|
w*******y
发帖数: 60932 | 14 Smart Alarm Clock: sleep cycles & noise recording:
http://itunes.apple.com/us/app/smart-alarm-clock-sleep-cycles/i
iOS iPhone
Great offer! The app is available absolutely for FREE 1 day only! Hurry up
and download!
- Smart Alarm Clock monitors sleep cycles and ensures the perfect wake-up
time!
- Records noises while you sleep, which is especially convenient if you want
to track your snore*
- 20 special wake-up and chillout tunes
- Detailed statistics: duration of each sleep phase, time of distur... 阅读全帖 |
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k**********n
发帖数: 23 | 15 成天有同志说闸有NOISE,害怕有担心破财,实在是没有必要.
1.如果车车能杀住,有点NOISE就只当是MUSIC好了,只要不是不踩闸都响.
2.如果还不放心,到GARAGE去查一下闸,很多是免费的,但不要说是有NOISE,
只说要查查是否安全就可以了.如果人家说没问题,你就走人吧,一路上
就只管欣赏你的MUSIC.
3.大部分因为"仅仅"是NOISE而花上1/2百换东换西的,换完后还会NOISE的,
为什么?因为工人师傅没有功夫给你严格按要求安装东东,该摸油的他不摸,
该加垫片的他不加,...一句话,他要急着宰下一位...
4.实在要取掉"MUSIC",你就加墙学习,练好内功,准备DIY... |
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w********u
发帖数: 5457 | 16 冬天闲来无事，把海钓的轮子拿出来整理一下。有两个penn slammer 560，稍微清洁了
一下，顺便把trip lever取下来，改成manual bail了。结果装回去以后，两个轮子都
有轻微的click noise，每转几圈等spool升高到最高点时才有一声轻微的click，声音
很轻但是仔细些能感觉到，不能判断这细微的声音从哪里来得。换上多余的spool，也
是一样。一怒之下把一个轮子拆了，没有发现异常，装回去还是有同样的click noise
。两个轮子，一个有满spool的编织线，另一个只有17Lb mono底线，入冬前都做过
service，没有改mamual bail以前都没有noise，改了以后都有同样的click noise。原
来改过好几个penn的slammer和sg的轮子，都没有任何问题。这click noise倒是都此遇
到。请问版上海钓的大牛们，能帮着分析一下啥原因不？谢谢了！ |
|
a******t
发帖数: 75 | 17 如果你有noise source和spectrum analyzer，就很简单。
你可以把noise source接在voltage supply (28V/0V)上,然后接DUT，最后DUT接在
spectrum analyzer上。用不同的电压28V or 0V，然后看spectrum analyzer上在感兴
趣的频率上的noise floor变化，然后根据公式和ENR算出noise figure.
你可能还需要一台ESG产生LO，如果需要LO的话。
用network analyzer也可以量，它有一个port可以控制noise source的supply,toggle
在28V/0V。但是network analyzer型号不少，每种用法不一样。具体需要读manual怎么
量。 |
|
ET
发帖数: 10701 | 18 回答这个问题，两个model 参数你可以看一下，
一个是af, 一个是kf.af 一般近似为1. 剩下的就是kf.
flick noise power 是正比与kf.
但是在<100nm， flicker noise power的计算公式有变化。
这个问题的严格问法应该是在何种条件下，一个channel length显然不够。 因为flick
er noise 反比与transistor area w*L.
同时，也是current的函数。
如果你问，在同样transistor area的情况下，which techhnology has better flicke
r noise performance? 或在同样的current 流过transistor下，flicker noise perfo
rmance..
corner frequency随着featured size decrease 而increase dramatically.
比如90nm下的corner frequency可以到MHZ ～ 10MHz. 65nm以下可能接近GHz.
而0.5um可能只是在hundr |
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b***n
发帖数: 441 | 19 书上都是直接算input referred noise,但是没说为什么要看input referred noise,
而不是output noise,
为什么呢。 |
|
s*****o
发帖数: 22187 | 20 由于高通特性，VCO noise在远小于带宽的频率下就基本看不到了，VCO的flicker在很小的offset下应该是看不到的，不过也要具体看你的process的flicker corner和带宽。除了VCO和Loop Filter，还有PFD, CP, Reference的noise也要考虑。所以小offset并不是-30和+40的简单叠加（你给的phase noise图里有一小段单调升的就是由于这个+40dB/dec造成的吧）。
可以先看看Hajimiri的"noise in phase-locked loops"，后面很多reference可以看。
noise |
|
s*********y
发帖数: 8 | 21 noise不是一个deterministic信号，用通常的想法来看average=0是不正确的。
integrator 的 input noise如果是white，output的noise power会随着时间增长
而linearly增长，也就是说output noise 的sigma和时间的square root成正比（phase
noise是unbounded就是这个道理）。于此同时你的output信号amplitude是随时间成正
比（信号 power和时间的平方成正比），所以overall的SNR还是随时间成正比。 |
|
d****6
发帖数: 971 | 22 一个普通的Rx chain, 从LNA开始到mixer然后是VGA
在fix gain 模式下观察baseband输出的noise floor
结果发现input port 设为open和loaded的情况下noise floor会差将近3个dB.
不太理解为什么，输出端的noise floor应该就是thermal noise+gain+noise figure，
为什么load和open能差这么多 |
|
w*******y
发帖数: 60932 | 23 Jawbone 2 Bluetooth Headset with Noise Assassin $24 with free shipping
Jawbone 2 Bluetooth Headset with Noise Assassin (bulk packed) $24 with free
shipping at walmart:
http://www.walmart.com/ip/Jawbone-II-Aliph-Bluetooth-Headset-with-Noise-Assassin/14967651
get them while they last!
Jawbone II Aliph Bluetooth Headset with Noise Assassin:
Ultra smooth, medical-grade plastic
Patented Voice Activity Sensor
Talk Time: 4 hours
Standby Time: 8 days
Range: up to 33'
Noise cancellation
This Jawbone Bl... 阅读全帖 |
|
w*******y
发帖数: 60932 | 24 Vaas DJ Noise Isolating Stereo Headphones with 7 Foot Cord - $7.99 Free
Shipping
Link:
http://www.icemonkey.com/vaas-dj-noise-isolating-stereo-headpho
The Vaas DJ Noise Isolating Stereo Headphones features Super Bass
performance that gives you the ultimate music experience. 40mm powerful
neodymium drivers deliver outstanding sound and the padded soft cushions
offer superior comfort and noise reduction in all environments. An
adjustable headband allows you to create a custom fit with your headpho... 阅读全帖 |
|
R*****h
发帖数: 194 | 25 我的outlander的cooling fan的切换开关会有挺大声的click noise，一开始偶尔听到
没当回事，后来经观察确定是 cooling fan 的切换开关的声音。一般在启动车后能听
到，因为这时候发动机不太热，所以cooling fan会自动的时停时开，一般是风扇启
动时开关的noise要比 停止时的开关noise大些。
我今天观察了我的camry，好像也有类似的click noise 不过小很多，不大注意得到。
大家的车呢？ |
|
d***y
发帖数: 263 | 26 3 ideas:
1. Analyze noise in siganling cascade and see how cells deal with it
2. screen for noisy genes using the constructs we have and pick up some to
analyze it
3. Analyze noise at the level of RNA decay, translation. Because most of the
work focus on txn level of noise. But I can't vision the significance very
well as txn is indeed the most important step in noise control.
???
is |
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z*****n
发帖数: 7639 | 27 White noise is a signal or process with a flat frequency spectrum. In other
words, there is equal energy in a given bandwidth at any centre frequency. In
time domain, the magnitude of a white noise process has normal distribution.
In digital signal processing, almost all types of noise are often approximated
with white noise since it has several useful statistical properties. For
example, it is statistically uncorrelated in time with any other signal,
including itself.
In practical applications |
|
s****h
发帖数: 3979 | 28 nonstationary time series, estimate the instanous noise level
有什么比较好的法子？ estimate里面的信号呢？
试过wavelet denoise,觉得noise成份太小了。如果把高频能量都算噪声的话。
有没有比较好的filter推荐？尤其是end filter? 有没有什么end filter可以
根据不同的phase shift来设计的？
想了个很土的法子，假设原时间序列为X,由无关的信号T和噪声N组成。
先算 var(X),downsampling 2采样后，得到X2(和T2, N2), 计算var(X2).
var(T) = 1/4 var(T2), 如果假设是gaussian noise, var(N) = 2var(N2),
假设是brownian motion， var(T) ＝ 2/3var(T2).如此可以估算噪声。
可是diff(S)的autocorre func在1,2,3...处都远大于0，这么算不太合理吧？
要是根据autocorre func和var(diff(S))来算，这个noise就是个 |
|
m*******l
发帖数: 220 | 29 我对这个一窍不通。请问：
１）white noise是如何产生的？所有的电路都会产生吗white noise？
２）如何确定采集的数据中有white noise？
３）如何消除white noise？能推荐几个算法吗？
先谢了。 |
|
W*****e
发帖数: 7759 | 30 ft,white noise and Gaussian noise are two different things. E.g. you can
have colored Gaussian noise, instead of white Gaussian noise... |
|
m*****t
发帖数: 3477 | 31 I have a question that related to this.
The equation I got from K.Martin's book between input and output refereed
noise:
Vno(f)^2 = Vni(f)^2 * A|j.2.pi.f|
Which means the output noise spectre is not only amplified by the gain, but
also shaped by the transform function. In other words, the transistor’s
bandwidth also kicks in at high frequency.
As a result the noise corner is pushed to the far end of frequency axis for
the output-refereed noise (10MHz range) compared to the input-refereed noi |
|
m*****t
发帖数: 3477 | 32 Just one individual mosfet.
I believe the 10Hz to 10KHz is the input noise corner.
While when you extract the noise model, you can not measure input noise, you
can only measure output noise current at Drain, and our measurement data
shows it's in the 10MHz to 100MHz range.
output |
|
s*****o
发帖数: 22187 | 33 PLL回路对VCOnoise是high pass特性。总的phase noise是所有noise sources通过回路
方程后的叠加。如果能看到<1K offset，phase noise还是单调减的（Reference noise
dominant)。
这些很多有关PLL的书里都有讲，可以看看。 |
|
p*********a
发帖数: 25 | 34 多谢~
是说VCO的noise在整个频段都dominate吗？
如果这样的话，Lesson公式里面VCO的Phase noise应该有-30 dB/dec的flicker noise
部分，而loop filter在low frequency应该是+40 dB/dec，所以我不清楚为什么大概是
那个形状，希望能推荐本东西看看。
noise |
|
y**c
发帖数: 6307 | 35 一般process 的flicker corner 是多少？ 我做VCO模拟的时候发现phase noise 斜率
都是-20db/dec,我很怀疑model没有包含flicker noise.
很小的offset下应该是看不到的，不过也要具体看你的process的flicker corner和带
宽。除了VCO和Loop Filter，还有PFD, CP, Reference的noise也要考虑。所以小
offset并不是-30和+40的简单叠加（你给的phase noise图里有一小段单调升的就是由
于这个+40dB/dec造成的吧）。 |
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b**********y
发帖数: 504 | 36 我有一个current source，用它来charge up一个capacitor，这个current source有
noise，那么经过一段时间，这个电容上的电压增加和noise有没有关系？ 还是只是和
current source的nominal current有关系？
我是这么理解的，虽然有noise，但是noise的average还是0, 所以对integrated
voltage没有影响。不知道对不对。
欢迎讨论。 |
|
c*t
发帖数: 452 | 37 noise在频谱上不会变化（考虑impedance把电流noise转换成电压noise），电压增加，
但是noise不变。 |
|
g****t
发帖数: 31659 | 38 这就是一个随机微分方程阿.
Cdv/dt=i+w, w是满足一定统计的随机变量,i是电流源的电流.
误差可以这样看:
我噪声系统满足:
Cdy/dt=i
所以C*d(v-y)/dt=w,
C*de/dt=w,所以误差就是噪声的积分.但这个几分本身也是随机变量.
我有一个current source，用它来charge up一个capacitor，这个current source有
noise，那么经过一段时间，这个电容上的电压增加和noise有没有关系？ 还是只是和
current source的nominal current有关系？
我是这么理解的，虽然有noise，但是noise的average还是0, 所以对integrated
voltage没有影响。不知道对不对。
欢迎讨论。 |
|
|
w*******y
发帖数: 60932 | 40 Logitech Ultimate Ears SuperFi 4 Noise Isolating Earphones -$29.99 after
Code Applied, with free shipping at logitech.com
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Deal LINKY:
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The real thing - Your music will sound the way it was meant tocrisp and
clean mid and high tones with detailed bass.
Not-hea... 阅读全帖 |
|
w*******y
发帖数: 60932 | 41 Ultimate Ears 200vi Noise-Isolating Headset (Plum or Blue) $19.99 free
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Plays, pauses, changes tracks, and adjusts volume from on-cord controls
Fits all ears comfortably with ... 阅读全帖 |
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|
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c****c
发帖数: 4 | 45 Someone here earlier had a post regarding belt makiing noise. Can't find the
original post. Any spray wouldn't fix it for long. You have to tight the
belt
up. It is not timing belt. To tell if it is A/C belt: turn on the A/c, rev up
the engine, if noise comes, it's a/c belt. If there is no noise, then is the
other belt. It's a fare straight forward job, could be done in less than a
hour,
if your have the right tools.
Good Luck! |
|
o*******g
发帖数: 553 | 46 The noises disappear on a smooth and even road. When the car is warm, such
noise also disappears at high speed (e.g., at high way). If it is the wheel
bearing problem, then the noise should be larger as the car's speed is
higher. Am I right? |
|
W***n
发帖数: 11530 | 47 Slipping/winding noise on startup and CVT malfunction
Feb 24, 2017
Dtfish
Hello civic owners! I am new to this forum and just recently bought a 2017
Civic hatchback. This forum seems to have a lot of great information and I
am hoping to learn a great amount from you guys and hopefully return the
favor! I have done a few minor visual mods such as clear corners, LED
interior lighting, LED headlights, and LED turn signals.
I have had the LEDs installed probably within the past 2-3 weeks. So within
... 阅读全帖 |
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c*p
发帖数: 186 | 48 【 以下文字转载自 Apple 讨论区 】
发信人: CIP (CC), 信区: Apple
标 题: bose noise cal 3 VS. B&W headphone,请教
发信站: BBS 未名空间站 (Tue Mar 16 18:49:20 2010, 美东)
想买个headphone,看中2款, 请比较下,价格都是300
Bose Noise cancelling 3 的话 可能音质不是很好,主要去noise cancelling了
B&W的 headphone design很漂亮,可是300的价格明显是B&W的低等货
该买哪个呢? 有没人都用过,音质哪个好? |
|
s******y
发帖数: 220 | 49 好像这款不错啊，
Bose® QuietComfort® 15 Acoustic Noise Cancelling® Headphones
但是amazon上要299d呢，觉得有点贵，
其实我也不是很需要noise cancelling，但是这个带着貌似很舒服。
请教有没有便宜点的不错的noise cancelling？ 在音质不错的前提下，舒服最重要。
btw，这款在outlet卖会便宜点吗？ 有deal没？
谢谢大家了。 |
|
d****n
发帖数: 233 | 50 One side of house house is next to a road. Every weekday morning, the school
bus noise and car noise wake us up around 6:30am. We thought about the
below choices to reduce the street noise inside the house.
(1) Replace the current double pane window with some sound-prevented pane,
which is expensive and may require replace the whole window instead of pane;
(2) Add one layer of window -- we have not found contractor who is willing
to do this;
(3) Add some thick curtain or thick wood blinder -- on... 阅读全帖 |
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