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全部话题 - 话题: bandwidth
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p******u
发帖数: 14642
1
来自主题: Military版 - 万州这地方
把高压电想像成宽带下载毛片,运煤铁路想像成地摊上卖的cd。latency上高压电是贼
快,但throughput就没法和下楼买一打cd比了。
Never underestimate the bandwidth of a station wagon full of tapes hurtling
down the highway. —Tanenbaum, Andrew S.
k**o
发帖数: 15334
2
这个其实不错,至少手机不用买3g data plan了。可能不能替代家庭宽带,因为
bandwidth肯定巨低。
W*******a
发帖数: 1769
3
来自主题: Military版 - 美国穷疯狂了 ATT DSL也要usage cap
别的国家都是速度越来越快,价格越来越便宜,美国是反着来
AT&T to cap data usage for DSL customers
By Dow Jones Newswires-Wall Street Journal
Posted today at 5:51 a.m.
AT&T Inc. said it would begin to cap DSL data usage for its customers
and begin to implement charges for anyone who goes over the limit.
The Dallas telecommunications giant said that customers who went over a
limit of 150 gigabytes of data a month three times would be charged $10
for every extra 50 gigabytes of data they consume. Customers on its
higher-end ... 阅读全帖
s******r
发帖数: 5309
4
来自主题: Military版 - 美国穷疯狂了 ATT DSL也要usage cap
In theory I think it is fair to put caps on certain users, who abuse the
bandwidth and slow down everyone else. Before the ISP can build higher speed
connections, it is helpful to set a generous cap to limit unreasonable
downloads.
So what is the cap ATT has set? Do you think it reasonable? Comcast caps
seem to work in a way that high volumn downloaders are automatically slow
down untill the cumulated usage over the past x days is below the limit.
w*******r
发帖数: 7276
5
Increasing the receiving antenna gain can boost the receive signal power and
increase the signal to noise ratio ( assume the receiver noise floor is due
to thremal noise at the front end). I bet the receive antenna used in moon
landing broadcast will be huge. BTW, the broadcast used analog transmission.
So the signal quality will degrade gracefully with lower SNR ratio, not
like the digital comm, once you are below certain BER, the image will not be
decodeable.
Estimation will be simple for a co... 阅读全帖
w*******r
发帖数: 7276
6
HEHE, you know nothing about satellite communication, this is for sure. Can
you tell me what kind of other distortion you are talking about? The
satellite channel is roughly a Line of sight AWGN channel. Tx and Rx antenna
gains, Tx power, distance between the two, and transmission bandwidth,
receiver noise floor basically are the factors influcing the performance.
What is your 信号传播中的噪声,引起信号变形? BTW, the deep space rx antenna
used in moon landing has a diameter of 230 feet ( around 80m), which is ... 阅读全帖
w*******r
发帖数: 7276
7
Just searched, and the video bandwidth is only 500 Khz. The broadcast is
directly from moon lander to earth antenna in Australia. It is definitely doable. Anybody doubt about this should shut their mouth, once for all.

moon
f*u
发帖数: 5923
8
废话,我用的就是bell,学校是不限量的。还有个加拿大人不太知道的小公司,我忘了
名字也是不限量的。但都要签合同,而且只有第一年不限量。
你到现在连bell都没用过关心过?你自己看看,你给我的链接有没有定量:
Performance you want
Download speed: up to 2 Mbps1
Upload speed: up to 800 Kbps
Internet usage: 2 GB of bandwidth per month
$28.90 /mo. 3
我靠,你在加拿大呆过没?就算稍微看看加拿大的华人网也知道了啊,你悲剧了。
p******u
发帖数: 14642
9
来自主题: Military版 - 中国特高压技术已成世界制高点
不是我知不知道的问题,计算机系N久以前的名言:“Never underestimate the
bandwidth of a station wagon full of tapes hurtling down the highway. —
Tanenbaum, Andrew S. ”
你电线传送能量也一样,再牛逼也没一艘30万吨油轮牛,再牛也没10分钟一趟的2万吨
变态扭曲大列煤车牛
t*******l
发帖数: 3662
10
来自主题: Military版 - 华为Mediapad 10 对比 ipad 3
GPU要比的话,就看pixel clock,render的frame rate,最大支持的
resolution等等,还有memory bandwidth,功耗啥的,这些有用

GPU
s****r
发帖数: 31686
11
no idea...
but the ornbitor, as reported, has semt back huge amount of data for mars
survey, three times of all past trips, so i guess it has very decent
bandwidth

orbitor能有1kW的发射功率么?
★ Sent from iPhone App: iReader Mitbbs Lite 7.56
s***d
发帖数: 15421
12
来自主题: Military版 - Dish Network的高速INTERNET怎么样?
快了 我们公司打算把moca搬到卫星上 其实只要bandwidth够大就好

★ 发自iPhone App: ChineseWeb - 中文网站浏览器
★ 发自iPhone App: ChineseWeb - 中文网站浏览器
o********s
发帖数: 971
13
lz恐怕连上千用户同时进行复杂操作的系统都没有做过才能说出这样的外行话。
真的很难。
租用多少服务器?
用什么样的load balancer?
用什么级别的cache?
用什么级别的bandwidth?
y*h
发帖数: 25423
14

互联通讯的性能主要有两个,一个是bandwidth,一个是latency,对于现在的超算而言
latency更重要。
c*****t
发帖数: 421
15

No bandwidth.
u***n
发帖数: 10554
16
Found an old article
http://www.lvse.com/site/republicwireless-com-5407.html
Republic Wireless是一家无线运营商,由美国一家宽带服务供应商Bandwidth公司分离
而来。2011年11月,新兴无线运营商Republic Wireless,将于11月8日开始以19美元/
月的价格提供无限制的语音、短信和移动数据套餐计划。Republic Wireless将在Wi-Fi
网络可用时通过Wi-Fi网络提供语音呼叫和短信服务。同时,当用户不在Wi-Fi网络内时
,该运营商将通过一张标准单元网络提供语音服务。Republic Wireless将通过向
Sprint购买整批的(网络连接)时间,然后向其用户进行再出售。Republic Wireless将
提供特别的Android手机,这些手机支持通过类似于UMA的技术在Wi-Fi网络上实现语音
呼叫,某些T-Mobile的Android和黑莓终端便具备这一功能。Republic Wireless同样将
提供无限制3G数据流量套餐计划。
如此的费用得以实现源... 阅读全帖
c*******n
发帖数: 2764
17
文科了,bandwidth不错,但是latency太高,很多应用没法用,例如股票交易,聊聊视
频倒是问题不大
e***i
发帖数: 58
18
Bandwidth is proportional to inverse of frequency
4G faster than 3G
Visible light is THz vs Wireless <100 GHz/satellite
Optical fiber infrared light, that's your bone of high speed network
But range /medium is the limitation for optical com
d*******3
发帖数: 8598
19
来自主题: Military版 - NIGMS 要劫富济贫了 (转载)
【 以下文字转载自 Biology 讨论区 】
发信人: sunnyday (胖头鱼。按斤卖就赚了), 信区: Biology
标 题: NIGMS 要劫富济贫了 (转载)
发信站: BBS 未名空间站 (Mon Jan 5 22:35:03 2015, 美东)
发信人: sunnyday (胖头鱼。按斤卖就赚了), 信区: Faculty
标 题: NIGMS 要劫富济贫了
发信站: BBS 未名空间站 (Mon Jan 5 22:29:34 2015, 美东)
革命了革命了!
今天收到NIGMS director 的公开信,里面明白着说单个实验室不应该拿到超过三个R01
(除非是clinical research), 并明白指出这个动向的原因是:
1。在钱的总数有限的情况下,一个实验室拿到多的钱就会导致另外一个实验室拿到的
钱变少。
2。大实验室对博士后和研究生培养不利,因为导师的注意力被分散了。
3。从统计上来看,大实验室的成果并不和资金成正比
A Shared Responsibility
Dr. Jon LorschPosted by Dr. Jon Lorsch o... 阅读全帖
w*********r
发帖数: 42116
20
该研究的主导者是哈佛大学终身教授Sendhil Mullainathan,主要合作者是普林斯顿大
学教授Eldar Shafir。此研究论文曾发表于美国《科学》杂志,基于此研究的书《稀缺
:为什么拥有太少后果会很严重?》(Scarcity: Why Having Too Little Means So
Much)也已出版。
这个研究源于Mullainathan对自己拖延症的憎恨。他7岁从印度移民美国,哈佛毕
业后在麻省理工学院任教经济学,获“麦克阿瑟天才奖(MacArthur Fellows Program
or MacArthur Fellowship)”后被返聘为哈佛终身教授。
而立之年就几乎拥有一切的他,觉得自己唯一缺少的就是时间。脑袋里永远有各种
计划,总想把自己分身去搞定所有事情,结果却常常陷入承诺无法兑现的泥潭。发现这
一问题后,Mullainathan便把手头正在做的国际扶贫研究和自己的问题联系起来。最终
,他竟发现自己面临的问题和穷人的焦虑惊人地类似。
穷人们缺少金钱,而他缺少时间。两者内在的一致性在于,即便给穷人一笔钱,给
忙得焦头烂额的人一些时间,他们也无法很好地利... 阅读全帖
c*********e
发帖数: 16335
21
来自主题: Military版 - 成人网站有多大 zz (转载)
【 以下文字转载自 Programming 讨论区 】
发信人: Jadeson (紫昂德帅), 信区: Programming
标 题: 成人网站有多大 zz
发信站: BBS 未名空间站 (Thu Jul 9 19:58:55 2015, 美东)
上网之人,多少都会接触过成人网站。这是一个举世公认的事实。
不过这是一个难以洞察的领域,因为相关数据少之又少。我们知道成人网站都是那些在
互联网上有着超高流量的网站。根据 Google DoubleClick 的 Ad Planner 服务(通过
cookie跟踪网民)显示,全球 Top 500 网站中,就有数十个成人网站。全球最大的色
情网站 Xvideos 每月网页浏览量(Page Views,PV)高达 44 亿,是 CNN 或 ESPN 新
闻网站的 3 倍,是 Reddit 的 2 倍。LiveJasmin 也不小。除了 Google 和 Facebook
等大站,其他网站在YouPorn、Tube8 和 PornHub 面前都是小巫见大巫。
虽然网页浏览量是一个很好的起始点,但它们仅告诉我们某些色情网站比某些非色情网
站要... 阅读全帖
d*b
发帖数: 21830
22
抗干扰跟距离没关系,不懂无线电通信的少说几句。frequency hopping也对付不了干
扰。frequency hopping更多的是为了加密和提高bandwidth和frequency的利用率
p****s
发帖数: 3184
23
抗干扰的一个物理实现就是增大发射功率,而敌我双方都可以增大发射功率,谁也不欠
谁的是吧。
增大发射功率的游戏玩到最后,对Rx而言,远端Tx的信号就有被近端Tx的信号变成背景
噪声的趋势。
论加密FHSS不如DSSS效果好。
真正提高bandwidth和frequency利用率的是OFDM。你如果指的是利用N个正交的FHSS频
段同时通信,对方干扰机的效率也会同时提高N倍。
我劝你不懂无线电通信就少说几句。
e***y
发帖数: 4307
24
来自主题: Military版 - 感觉python的前途堪忧
人当然感觉不到了,你要是控制一个高速移动的东西还要高精度,10ms就是渣。就说说
前几天版上讨论的清华搞出来的光刻机吧,那东西控制系统的bandwidth至少要40khz以
上。类似的东西还有很多,而且还要很多人手优化的,你还敢大言不惭的说纠结“一点
”时间。你不懂就歇歇吧,别给码工丢脸了。
m**c
发帖数: 7349
25
来自主题: Military版 - One port, one cable
ast year Intel announced that Thunderbolt 3 would use the same port type as
USB-C. Meaning that depending on the type of device connected to it, every
Thunderbolt 3 port will also work as a USB-C port and every Thunderbolt 3
cable will work as a USB-C cable and vice versa (as long as you get a
qualitative USB-C cable.)
When working as Thunderbolt 3, the port delivers up to 40Gbps bandwidth and
as USB-C, up to 10Gbps. Both types of connections allow for the delivery of
data, audio and video, maki... 阅读全帖

发帖数: 1
26
来自主题: Military版 - 所有的bandwidth都用在舔米国
添普京没用。太穷,舔不出油水来,反要倒贴。
f******o
发帖数: 2469
27
来自主题: Military版 - 特别希望中美早点打热战

Netflix utilizes 15 percent of the internet bandwidth, up to 40 percent in
the evening
w*********r
发帖数: 42116
28
来自主题: Military版 - 5G的基本标准
5G systems in line with IMT-2020 specifications,[3] are expected to provide
enhanced device and network-level capabilities, tightly coupled with
intended applications. The following eight parameters are key capabilities
for IMT-2020 5G:
Capability Description 5G target Usage scenario
Peak data rate Maximum achievable data rate 20 Gbit/s eMBB
User experienced data rate Achievable data rate across the coverage area
1 Gbit/s eMBB
Latency Radio network contribution to p... 阅读全帖
S*********e
发帖数: 4
29
上个月还20Mbps,今天发现40多了

发帖数: 1
30
真鸡巴落后
S*********e
发帖数: 4
31
我擦,你说说你是啥牛逼的服务?麻痹的

发帖数: 1
32
光纤入户啊,上行下行一个速度

:我擦,你说说你是啥牛逼的服务?麻痹的
S*********e
发帖数: 4
33
那也有gigabytes和一般的区分。再说google fiber和Verizon 不是每个城市都有。吹
什么牛逼

发帖数: 1
34
所以说你在落后地区嘛

:那也有gigabytes和一般的区分。再说google fiber和Verizon 不是每个城市都有。吹
:什么牛逼
S*********e
发帖数: 4
35
尼玛土鳖。google fiber恰恰是从落后地区开始服务的

。吹

发帖数: 1
36
Google fiber早嗝屁了

:尼玛土鳖。google fiber恰恰是从落后地区开始服务的

发帖数: 1
37
来自主题: Military版 - 某老酱说网络latency无关紧要
反正internet多数bandwidth是用于porn而已

发帖数: 1
38
He adds that while communication by servers on the ground might take
hundreds of milliseconds, in the cloud the same operation may take only one
millisecond from one machine to another. “It’s orders of magnitude faster,
and in the cloud we can easily afford more bandwidth resources, too. The
photons have less distance to travel in the cloud than on the ground. All
these factors make outsourcing the decision-making to the cloud more
advantageous.” The researchers say this new approach of enabling... 阅读全帖

发帖数: 1
39
来自主题: Military版 - 英姿飒爽的白牛特别值得交往
没有交流体液都是浪费bandwidth
Z**S
发帖数: 1211
40
There is no technical challenge in ship identification
by satellite. In the worst case, shoot a lot of satellites
up during war time, money is not an issue in such
situation.
First a set of surveillance low-res satellites
(optical or radar), interesting targets
will be identified by the on-board computer. to save
bandwidth, only image/signals around the target is
sent back to the ground control for verification, together
with their coordinates.
Then a set of high-res optical satellites are instr... 阅读全帖
g**1
发帖数: 10330
41
Gorgon Stare test uncovers major glitches
Test memo reveals current system unreliable and ineffective
By William Welsh
Jan 24, 2011
Gorgon Stare, a sophisticated video capture system with nine cameras
that provides wide-angle surveillance images, has significant
operational glitches and is not ready to be fielded, reports Colin Clark
at Defense Buzz.
The recommendation that Gorgon Stare needs further improvements because
it works less than half of the time was made by the 53rd Wing of the Air
Co... 阅读全帖
c*********s
发帖数: 85
42
pardon my simplistic example but flying "straight and level" is about as
much as modern "AI" can handle (and they're generally called automation, not
AI).
and huahuaniu is right "完全跑题了,人工控制的无人机现在有的是,根本无需讨论
". Bandwidth and latency are the only problems with remote control and have
very little to do with artificial intelligence.

往地
c*********s
发帖数: 85
43
yes, that's true if the memory/computing requirements to find solutions to
this highly dynamic cooperative multi-agent problem (in real-time)
physically fit within the body of each aircraft (otherwise we right back to
bandwidth problems)
m*****t
发帖数: 3477
44
我预测不出来,别说我不是大拿,就是iSuppli这种专业市场分析公司,也不是一两个
analyst就能预测出半导体行业走势的。
还有一个问题,不是好的技术都有机会拿出来普及的。特别是在现在这种board room体
制下,大的技术革新马上拿出来用的话,一来对长期保有优势不利,二来会受到相关产
业链厂商的巨大阻力。
还有,不是小就是好,除了个别的纯数字ic,像cpu,mem和dsp,其他的应用都是致力
于系统集成,最好是rf, analog, mixed-signal,power mgr和digital logic都做在一
个die上,至少是一个pack里面。这时尺寸大多是由paasive或者power device决定的,
transistor小点优势并不明显。还有III-V等等其他材料的更新。
个人观点,对于一般民用产品来说,现在不像20年前,很少有硬件性能成为系统瓶颈的
,而基本都是在wirless data bandwidth有限制下。产品用户体验的提高靠软件系统的
改善就能完成大部分。
唯一的例外就是power mgr,移动和植入电子品需要更久的待机时间和更好的散热,不
过这方... 阅读全帖
m*****t
发帖数: 3477
45
我预测不出来,别说我不是大拿,就是iSuppli这种专业市场分析公司,也不是一两个
analyst就能预测出半导体行业走势的。
还有一个问题,不是好的技术都有机会拿出来普及的。特别是在现在这种board room体
制下,大的技术革新马上拿出来用的话,一来对长期保有优势不利,二来会受到相关产
业链厂商的巨大阻力。
还有,不是小就是好,除了个别的纯数字ic,像cpu,mem和dsp,其他的应用都是致力
于系统集成,最好是rf, analog, mixed-signal,power mgr和digital logic都做在一
个die上,至少是一个pack里面。这时尺寸大多是由paasive或者power device决定的,
transistor小点优势并不明显。还有III-V等等其他材料的更新。
个人观点,对于一般民用产品来说,现在不像20年前,很少有硬件性能成为系统瓶颈的
,而基本都是在wirless data bandwidth有限制下。产品用户体验的提高靠软件系统的
改善就能完成大部分。
唯一的例外就是power mgr,移动和植入电子品需要更久的待机时间和更好的散热,不
过这方... 阅读全帖
w***g
发帖数: 5958
46
来自主题: USANews版 - 关于net neutrality
Facebook上已经在传了. 我先来打一剂预防针.
网页:
http://www.theverge.com/2016/11/9/13579800/net-neutrality-donald-trump-election-open-internet
我的反驳:
Net neutrality is in alignment with all other democratic agendas like
bathroom neutrality. I consider this article a leftist propaganda, in that
it assumes net neutrality is 100% good without explaining to the reader what
net neutrality actually is or explaining what its pros and cons are (as a
PhD in computer science, I totally believe some explanation is deserved).... 阅读全帖

发帖数: 1
47
如果川普真的说了这些没常识的话(which 我满怀疑的,是不是又是捏造?),他又在
开空头支票。
首先,联邦地方分权明确,让 FBI(或其他联邦单位)插手地方治安的法源何在?
其次,芝加哥市是否乐意与联邦合作?传统上地方已经不欢迎联邦介入了,现在联邦如
果真的扩权,地方反弹肯定很大,拒绝合作。
第三,FBI(或其他单位)真有那么多的 bandwidth?真的有多余时间去管闲事?
川普爱搞民粹,常常说些好听的话,例如反全球化或者挑战中国,傻川粉听了一阵鸡冻
,但究竟有多少可行性?就只能呵呵了。
a***r
发帖数: 594
48
来自主题: USANews版 - Death Date Announced For The Internet
what a boat load of crap. the Obama net neutrality shit is a regulatory hack
to protect the monopoly of google, netflix, etc, over the information and
content flowing through the internet,
to protect the profit margin of just a couple gigantic corporations who use
well over half of the internet bandwidth.
to protect the distortion and censorship on information by just a handful of
media companies.
the Obama net neut regulation should be scratched completely.
p**********d
发帖数: 7918
49
你有沒有看文章啊,作者有引用證據啊。
The Internet connection providers, or ICPs, on Monday filed a formal
complaint to government officials about the reduction in bandwidth, in some
cases about 10% of what they had bought, according to Mr. Ranjbar.
One Tehran resident, who asked to be identified only by his first name,
Behzad, said his home broadband connection has slowed so much in the past
few days that it's almost unusable. Simply loading Google Inc.'s home page,
he said, takes up to a minute.
"At the moment,
h****n
发帖数: 1952
50
来自主题: WorldNews版 - Joseph Andrew Stack的宣言
被md河蟹了,
This website has been taken offline due to the sensitive nature of the
events that transpired in Texas. Although the customer exceeded their
bandwidth limits earlier today, due to numerous requests, we have added
credit to this account to keep this site live for informational purposes. To
see an archived version of the original letter, please go here: http://www.thesmokinggun.com/archive/years/2010/0218102stack1.html. Please visit our forum if you wish to discuss anything related to this
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