Lo-Fi Phones and the Future 228
bossanovalithium writes "Back in 1936 — 74 years ago — boffins accepted that about 3.3Khz was the accepted frequency that telephone calls are going to run on and it's been like that, generally, ever since. Call quality is reasonable but leaves a lot to be desired. Think calls from Skype to Skype where quality is often crystal clear." It's crazy to me that (for people with decent mics at least) Ventrillo sounds better than corporate conference calls.
Insightful commentary (Score:2, Funny)
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The Coral Cache version works.
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Is it just me, or does anyone else think it'd be somewhat wise to have Slashdot story submission code automatically turn links into Coral Cache links?
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It's just you. We don't read the TFA; the only reason we click on those links is we like to crush people's servers. Get with the program, please.
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There's a Firefox plugin [mozilla.org] that does this for you.
Ignore the "Not available for Firefox 3.6" message - you can override compatibility checking with the Add-on Compatibility Reporter [mozilla.org] plugin and it works just fine.
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Thanks. Now, what to do when faced by...
Based on your corporate access policies, access to this web site ( http://www.techeye.net.nyud.net/business/how-and-why-telephones-are-going-to-get-a-whole-lot-better [nyud.net] ) has been blocked because the web category "Proxies & Translators" is not allowed.
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Find a proxy that your company doesn't blacklist and connect to the nyud.net proxy via the other proxy? Just keep chaining them together ... eventually something is bound to work.
it's bandwidth, not frequency. (Score:3, Informative)
I bet boffins did. But they were wrong. Serves them right for being boffins, I suppose.
It's bandwidth, not frequency. In the USA, POTS (Plain Old Telephone Service) lines are 3 KHz, specifically 400 Hz to 3.4 KHz. 400 Hz is the low frequency, and that is way above the lowest tones in most voices; while 3.4 KHz, the highest frequency passed, is way below the highest tones in most voices. But
guess what (Score:4, Informative)
I live in 3rd world country and our major cellphone networks support hd-voice codecs.
Re:guess what (Score:5, Funny)
Only HD?
You're all a bunch of suckers buying HD phones and HD TVs, when Ludicrous Definition is just around the corner.
Re:guess what (Score:5, Funny)
Ludicrous Definition? Pffft.
Here in Scotland, our TV definition has gone plaid.
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Bah, my phone has Dolby Prologic, THX, dts, EAX, D3D and 7.1
And I'm just in alabama.
Mobile Phones taught us to accept bad voice (Score:2)
The VOIP world has spent a lot of time arguing about codecs, and is a MOS score less than 3.9 adequate for toll quality, and the IP PBX business was having to convince customers that 8kbps G.729 codecs were good enough for business, you didn't need full 64kbps G.711 uncompressed voice. Fortunately, cell phones became universal a few years back, so customers got used to low-bandwidth sound, compression, and cheap little microphones with road noise and passing trucks in the background, and somehow the MOS sc
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I live in a first-world country where we have HD sunglasses [hsn.com].
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You barely get a signal?
I'm so jealous....
Bandwidth (Score:3, Funny)
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This is the sound of one server melting down....
Queue Time Limit Exceeded (Score:2)
503. (Score:2, Informative)
hmm, well it is running IIS...
Coral Cache .... (Score:5, Informative)
Just click here [nyud.net] and avoid the Slashdotting...
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Until the Coral Cache caches the "We've been slashdotted" page.
Not Boffins, Evolution! (Score:3, Informative)
Boffins did not decide this. It is a consequence of the evolution of human speech, both vocalization and hearing. The part of our speech that encodes content is the part that telephones have been engineered to convey. It's actually less than the 300-3400 Hz band, there's a mostly-useless band segment between the low frequencies and the higher ones that can be left out without much effect on speech recognition.
There have been a number of "hi-fi" schemes for telephony and bandwidth-limited radio. Some add ba
Let's Make it Narrower! (Score:4, Informative)
Vent conference calls? (Score:2)
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The hell with Ventrillo, we switched to Mumble 6 months ago and would never go back
http://mumble.sourceforge.net/ [sourceforge.net]
Jonah HEX
Bandwidth not Frequency (Score:5, Informative)
I can't even read the referenced article but I can tell you the phase ""Back in 1936 — 74 years ago — boffins accepted that about 3.3Khz was the accepted frequency that telephone calls are going to run on" is totally wrong.
What they meant to say was that the relevant bandwidth for understanding speech would be from 100Hz to 3.4kHz. Making the required bandwidth be 3.3Khz.
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Ha... if 3.3KHz was the accepted frequency all they'll hear probably sounds like bird chirping.
No, that 3.3 kHz would be a constant sine wave. Turning that sound on and off requires some bandwidth.
Re:Bandwidth not Frequency (Score:4, Funny)
Damn it, 3.3Khz is more Khz than anyone will ever need!
Re:Bandwidth not Frequency (Score:4, Informative)
Actually the bandwidth is 3.1kHz, running from 300Hz to 3.4kHz. This is the range of frequencies that conveys the most information relevant to intelligibility. Anything else makes it easier to recognise the speaker but doesn't make it easier to understand them and can make it harder to understand in noisy environments.
If you low-pass filter speech below 3.4kHz then mostly you only lose the high frequencies in sibilants, but you also filter out a lot of background noise. If you're really interested you could set up a media player to play recorded speech through a tunable bandpass filter and see what you can filter out before the speech becomes hard to understand. Once you've got a feel for how the filters affect the intelligibility, try playing it back in a noisy environment (or mix in a recording of the inside of a car or something).
The 300-3400Hz filter is pretty standard in communications, and it crops up in all sorts of places. I wrote a software-defined radio app that defaults to 300-3400 but is easily tunable up to 15kHz for either low or highpass (although if you highpass filter at 15kHz you won't hear much). Occasionally I'll use it to roll off above about 2.8kHz to remove high-pitched squeaky noises from adjacent transmitters.
Obligatory screenshot: http://www.gjcp.net/~gordonjcp/lysdr.jpg [gjcp.net]
You can see the yellow strip representing the passband of the filter. The (fairly weak) signal shown doesn't really have any strong components much above about 2kHz, and I could reduce the noise by sliding the leftmost (lowpass) filter in a bit. A quick explanation of what you're looking at - that's a spectrum plot of a chunk of the 7MHz amateur band, with lower frequencies on the left as indicated by the scale at the bottom. Since on 7MHz we use lower sideband (LSB) [wikipedia.org], the higher audio frequencies correspond to lower RF frequencies (further away from the red tuning cursor).
Re:Bandwidth not Frequency (Score:4, Interesting)
Actually the bandwidth is 3.1kHz, running from 300Hz to 3.4kHz. This is the range of frequencies that conveys the most information relevant to intelligibility. Anything else makes it easier to recognise the speaker but doesn't make it easier to understand them and can make it harder to understand in noisy environments.
That's a myth, 3.4 kHz is not high enough to tell the "f" sound from the "s" sound over the phone. Similarly for "v" vs "z" and a bunch of others. If phones were that intelligible, people wouldn't have to say "a as in alpha, b as in bravo, ...".
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Another thing is that while Skype calls can be better, they're often among the worst that I've received too. If you're doing it with the $1 mic that came with the computer, then you're probably doing your recipient a disfavor. It isn't about Skype per se, it's a matter of where the weakest link is, even a crappy phone seems to have a more tolerable mic pickup than standard computer mics.
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But really, I wonder if the article person confuses (sampling) frequency with bandwidth? Not that they used to be sampled, but that's a common measure. In that case, these would be equivalent to 6.6 kHz sampling rate. I know, like it makes a big difference. But still...
Many people seem to confuse bandwidth with data transmission rate, so you can imagine the confusion if the author had actually used the correct terminology.
Its crazy to me... (Score:2)
What's crazy to me is the summary goes from 3.3khz to Skype in the quoted portion and somehow jumps to Ventrillo with nary a through of a segue.
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Perhaps the quibble is over the definition of "limited".
Your random headset mic on skype to skype produces an exceptionally good connection, vastly superior to anything sent thru the phone system, such as when you skype to phone.
It would be kind of messy remembering to switching mics just because the next number you dial thru skype was going to be POTS.
Latency? (Score:4, Interesting)
My experience with Skype, VOIP, and even to a lesser degree cell phones is that they all have latency worse than landlines. Is this actually true?
We were considering switching our business phone lines over to Time Warner voip. I talked to one of their people on the phone. My side was landline, theirs was time warner voip. The delay was awful. We kept talking over each other. If that's the best Time Warner can do, I was very not impressed, and as a result was still have our more expensive landlines.
Is there anything to my complaint, or have I just had bad luck??
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My vonage service is indistinguishable from a copper connection.
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Depends on your connection speed. Sometimes when playing a game that taxes my computer & Internet connection I can say something in Vent and then ~1 min later when someone else says something, I can hear my comments playing in the background.
So it is possible to have latency issues.
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My only landline is a VOIP service from my cable provider (Net, from Brazil). There are some downsides (like the fact that the line goes down when the power does, or the time it takes from the moment you switch on the adapter to actually getting a dial tone, which is a problem when you return home from a trip), but I've NEVER experienced a voice delay. YMMV, of course, but Net allocate a fixed bandwidth to the voice service above the amount you have for your Internet connection; and they give voice a much h
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I have a telecoms book which explains that at a certain point in the past, calls early in the morning EST in the oversubscribed east coast corridor (which I recall as Boston to Washington) were sometimes circuit switched via California, since the east-west links had a lot of excess capacity at 05:00 PST. This strategy sucked for the phone company if the call lasted more than th
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I've gone from land line to Vonage to running Asterisk with several VOIP gateway services, which I've been doing for about 5 years. VOIP quality primarily depends on routing. I've currently got a VOIP gateway provider with ping times 40 ms and the latency and jitter during calls is not a problem and definitely better than a cell phone. I can't control how the gateway routes calls and it seems that some area codes I call have some noticeable latency, but overall it is a good experience. I've had many pe
Re:Latency? (Score:4, Informative)
Latency of the call is highly variable, and dependent on two factors:
1. How much latency is in the network?
2. How much latency is introduced by the VoIP conversion itself?
I joined Vonage about 5 years ago. On my first ISP, I got a little over 3/4 second of latency on a really good ISP connection. This was annoying, but not enough to really make me want to spend two and a half times as much for a landline with a non-portable number. Eventually, Vonage went through a stretch of upgrades to the firmware on my adapter and the latency dropped to about 1/4 second (all but unnoticeable). However, I traveled a lot a couple of years later and found that hotel connections tend to have a lot more latency, so I got a cheap prepaid cell for when I was on the road. I settled down to a local job again and had a lot of trouble with my new ISP for a while, resulting in poor call quality and very high latency, then we got that straightened out and I was back to 1/4-second delay, which was pretty much the rule until my company issued me a cell phone with unlimited minutes, so I ditched my Vonage line because I didn't use it. But friends who have joined since have reported very low delays, almost unnoticeable, as long as their connections were good.
So the technology has improved, but you are still dependent on someone who gives you the better tech, and on a good Internet connection between you and the adapter on the other end where the call is bridged back to a POTS network.
However, landlines have a few features that people have a hard time giving up. Whether you are willing to pay for them is a different matter.
1. No need to manage power to a device. If the wires are up, the connection is the telco's responsibility.
2. Real, honest 911 with pretty much 100% accurate location awareness. Your tax dollars at work (which are a generous chunk of the difference between telco and VoIP).
3. "Feedback loop" (you can hear yourself talk in your earpiece). This helps regulate your volume, which is why people tend to talk louder into cellphones (they don't get that feedback).
4. No-delay talking. When telcos use VoIP, they use really high-end gear and fast networks to support it.
5. True DTMF support. This has gotten a little better, but VoIP for the most part can't carry DTMF tones to sufficient clarity, so your local VoIP adapter has to recognize an attempt at one and generate a fresh tone that your analog gear can recognize. Conversations with people can occasionally be interrupted by a "BEEP" as your VoIP adapter misidentifies a sound in their voice or the background as a DTMF tone and faithfully reproduces it, and you may get occasional complaints of the same issue on the other side . If it fails to reproduce when needed and you run a menu system, your customers will really hate traversing your menus.
The net result of all of that is, well, you get what you pay for. Telcos are expensive, but you are pretty much guaranteed a good call every time. Most of the gear you probably own was built to analog specifications, and the telcos are good at maintaining that spec.
For most of us, cell or VoIP is sufficient. We're OK with slight delays, a less-than-perfect reproduction of our voices, the occasional errant DTMF tone, etc.
If you run a business and you strongly feel that clear telephony is a vital part of your business, then it's probably worth paying for in your case, or at least paying for a REALLY good Internet connection and high-end VoIP gear, not consumer-grade stuff. Though you could always run one VoIP line for a while and see how it works out (just use it for less critical calls to start with).
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3. "Feedback loop" (you can hear yourself talk in your earpiece). This helps regulate your volume, which is why people tend to talk louder into cellphones (they don't get that feedback).
The term you are looking for is sidetone.
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Describing Wal-Mart's business model to a 'T' - you're willing to put up with almost any
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Re:Latency? (Score:5, Informative)
An MIT student did his thesis on Voice vs. Data lantency on cell phones, you might be interested in his methodology and results:
Quality of Service Analysis for Audio over Cellular Voice Networks [mit.edu]
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Have you tried it any time recently? I haven't had a noticeable delay using Skype on a notebook in ages. There used to be a delay when I was using Fring with an iPhone 3G, but the official Skype app also works with no noticeable delay.
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My experience with Comcast VOIP has been I cannot tell the difference except that, if anything, the sound is clearer than POTS. I don't notice any significant latency. It is difficult to beat POTS for latency, though. For voice they typically send a burst of compressed voice data every 10 or 20ms. POTS typically uses a dedicated very lot latency network which will have a lower latency than packet switched networks.
Re:Latency? (Score:5, Informative)
I've been working with VoIP in enterprise environments for a little over a decade. Latency is indeed a real issue and has to be considered, however it's not as restrictive as you might think. Generally speaking, if your ping is 150ms round trip you will not be able to distinguish a delay during an audio conversation, unless you're in the same room with them. Latency up to 300ms round trip is generally considered acceptable.
Cell phone conversations may or may not utilize VoIP during some legs of their calls. If they do, it's not between the phone and the tower unless you're using Skype or some other 3rd-party application on the phone. There is a distinction between encoding/decoding analog voice and how the digital signal is transmitted; you cannot consider cell phone calls to be synonymous with VoIP even though they do share some characteristics.
While cell phones do have highly variable horsepower in the CPU, the encoding/decoding is handled in purpose-built hardware chipsets, not on the CPU. It's unlikely that the type or brand of phone has any but a negligible difference in latency. Most people do not notice the latency in cell-to-cell conversations, so it may be that you're more sensitive to it for some reason.
Another factor is that some of the widely-deployed audio codecs used to compress voice were built and tuned for English speakers. Those speaking very dissimilar languages, such as Mandarin, may find that audio quality is poorer even on the same equipment.
Lastly, there are defined codec standards for wideband audio. Cisco has been including them on all their phones for several years; I assume other VoIP manufacturers have as well but do not have personal knowledge. I found that some customers did not like using them, as they are accustomed to hearing some level of white noise in the background and are prone to misinterpret a period of silence as call disconnection. If you've ever asked "are you still there?", the clarity of the call was greater than you expected or, possibly, wanted. Even with normal quality codecs we've had to inject comfort noise for years.
Little of the above applies to video. That's a whole different story.
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Echo is always on the analog side.
What usually happens is the audio from the handset feeds back into the mic on the same handset. With a traditional very-low-latency phone call you still have echo, but you hear it so close to when you speak that you don't notice. The larger the latency, the more evident the echo.
In loud environments (like retail stores) the user will often crank up the volume on their handsets, and that makes echo even more noticeable. I did a deployment for about 250 retail stores some yea
How many died? (Score:5, Funny)
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So how many boffins died to bring 3.3Khz to our phones?
74 years ago when they made that policy? I'd say probably all of them.
worst summary ever? (Score:4, Insightful)
This has got to be up there in the competition. Doesn't layout a summary of the article. Offers an opinion about some piece of software I've never heard of. No hint of whether or not there's a proposed solution.
Bizarre.
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Not to mention, no indication of what a boffin is. Had to look that bit up.
Who saves your data? (Score:2, Interesting)
At 3KHz, with compression, you can now record every conversation, from birth to death, of a connection. Think about who wants that data. I would guess that from the moment you aquire your first cell phone contract, the providers are saving all your conversations. What's the point of a wire tap when that data is available upon request? In our post 9/11 world, I would be amazed if it doesn't already work that way.
Guild Chat... (Score:2)
A conference call over Vent would be funny.
+Guild Chat
+Rankor's Room
+Raid1
+Raid2
+Raid3
+Business Conference
"Now if all the raid members would kindly leave out channel so we can get down to business... No Stan, get out of Raid1 chat..."
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Some of the calls on Ventrilo Harassment were taking place on "corporate vents", which despite that were for some reason wide open.
You think talking on an iPad is wrong (Score:2, Interesting)
But in actual practice, if you have a $40 Wireless N router, an iPad makes a very cheap phone.
And it comes with the ability in the new model releasing later this year to use iFace to share pics while you talk with iSkype.
Computers were originally used mostly for accounting, calculating missile trajectories, and for other stuff, but we don't use them to do that now, for the most part.
Don't give away the secret! (Score:2)
Shhh, if Jobs finds-out you know the game-changing "camera" feature of the iPad 2.0gs some poor guy in China's going to get axed.
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So you never have to go anywhere but campus, coffee shops, libraries and home? Are you a character on "Friends" by chance?
Anyway, for the rest of us, real phones are handy.
Noooooo!!!!!! (Score:4, Funny)
no reason it can't be backwards compatible (Score:2)
The bare wires to the phone support a lot more than 3.3Khz of bandwidth, so there's no reason why your old phone couldn't continue to work. Theoretically all the work could be done in the telco equipment. Worst case, you'd have a little breakout box with RJ11 one one end and RJ45 on the other.
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Yes, but the OP has something new to bitch about. Which given his age (he still has a TV purchased in 1936, I'm guessing he's not young) is probably a prime source of entertainment. So really it all works out, don't it?
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He's talking about his 1936 Telephone.
Most likely black, and definitely dial.
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Actually, I got my converter box. It doesn't work all that well compared to the reception I had before. It turns out that a bit of snow and occasional crackle is much easier to deal with than frozen picture and silence. Meanwhile, the freed up spectrum was all snapped up for more of the same from overly greedy telecoms.
Ignore the slashvertisement for XConnect (Score:5, Informative)
the problem has been solved yet not been implemented widely. It's called ENUM and freely available and open. No need for proprietary XConnect stuff to implement this functionality, it's based off DNS and thus already has a widely available penetration. All people (and large corporations) need to do is actually use it.
They were not prepared (Score:3, Funny)
Back in 1936 — 74 years ago — boffins accepted that about 3.3Khz was the accepted frequency that telephone calls are going to run on and it's been like that, generally, ever since.
Back in 1936, nobody expected they would have to scatter from the Lich King's defiles while a single player messing that up would cause a wipe.
Mirror (Score:2)
http://www.techeye.net.nyud.net/business/how-and-why-telephones-are-going-to-get-a-whole-lot-better [nyud.net]
Right on the spot (Score:5, Informative)
I was pondering this exact stuff just today at work, since a phone call sounded kinda crappy, barely acceptable until I needed to involve 2 more people and put it on speakerphone, it became so bad we had to give up. I dropped the phone call, switched to skype, and damn what a big difference. The crappiness of POTS is ridiculous indeed, and although I see the need for compatibility, it can't die soon enough.
By the way, if you like Ventrilo, try Mumble [sourceforge.net], which, apart from being free and open source, which can't hurt according to the /. crowd, has really awesome sound quality, and you can setup your own private instance in minutes. Plus, for the MMO crowds, it has extremely low latency, awesome echo echo echo echo cancellation and built-in auto volume normalization (helpful when That Loud Guy Without Headphones keeps pressing his PTT and everyone's in pain)
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By the way, if you like Ventrilo, try Mumble [sourceforge.net], which, apart from being free and open source, which can't hurt according to the /. crowd, has really awesome sound quality, and you can setup your own private instance in minutes. Plus, for the MMO crowds, it has extremely low latency, awesome echo echo echo echo cancellation and built-in auto volume normalization (helpful when That Loud Guy Without Headphones keeps pressing his PTT and everyone's in pain)
I absolutely LOVE Mumble, but two points...
1) Vent has normalization also, you just have to Google how to do it.
2) None of your pugs will use Mumble. Period.
It genuinely is a superior product, but would be greatly improved if the server would be so kind as to interface with a Ventrilo client. Ease of transition, and all that.
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Yep, I did, and it didn't work well enough for me even after fiddling with the values. I ended up having to adjust almost every single speaker, and everytime they reinstalled their pc / changed their nick I had to do it again.
eek, pugs :)
It's a real problem. (Score:4, Informative)
While bandwidth is low, that's not the big problem. Quality is really hard to fix over networks with time jitter. Which is why VoIP and cell phone voice quality frequently suck. The best phone audio today is from an ISDN phone to an ISDN phone - end to end uncompressed full duplex digital with hard bit timing synchronization. (ISDN voice never caught on in the US, but it's widely used in some European countries.)
Wire-line telephony is 8 bits sampled at 8KHz, so the highest potential bandwidth is 4KHz. Compare CD audio, 16 bits sampled at 44.1 KHz per channel. Cell phones are worse; they're usually compressed down to 9600 baud or so. There are some high-end video conferencing systems with higher-bandwidth audio, but they're rare.
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It's also widely used for telephone interviews on TV/radio, due to the improved clarity.
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Excuse me? (Score:2)
It's crazy to me that (for people with decent mics at least) Ventrillo sounds better than corporate conference calls.
Woah, maybe better than YOUR corporate conference calls, but definitely not all. Apparently you've never heard of "HD Voice [wikipedia.org]".
WB-AMR is comming to your mobile (Score:3, Informative)
Hi!
In a year or two, most GSM/W-CDMA networks will be upgraded to WB-AMR codecs.
Orange is already using it in Moldova and London, others are testing.
It is marketed as High Definition Voice.
WB-AMR uses 16 kHz sampling instead of classic 8 kHz . Together with better voice compression,
higher quality of voice is using same capacity (say, 12.2 kbit/sec) as we use today.
Of course, PCM is out.
Both sides of connection must support WB-AMR, and everything in between as well,
so for few years it might not be available across different networks.
If one terminal can not use it any more (maybe due to handover to GSM cell not supporting WB-AMR),
fallback to AMR/EFR is made on both sides, using 64k/56k PCM inbetween.
Technology is avaialble for quite same time, but terminal vendors are slowing it down.
Some 20% of all terminals have to support it, otherwise it makes no sense for operator
to buy all SW needed to implement it network wide.
Funny: good old GSM will soon get higher voice quality as ISDN.
73
Bandwidth isn't today's biggest problem with calls (Score:5, Interesting)
I don't have an issue with the frequency range, but certainly do with latency, and the lack of true duplex any more!
I find (found) that talking on a true analog line is MUCH easier than any digital line today - be that Skype, cell phones, or even land lines in most countries. I'm always amazed when traveling abroad when I make a local call on a truly-analog system how much nicer the experience is!
With today's systems in "Westernized" countries, you can't even have an effective 2-way conversation. The duplex performance sucks - you can't hear anything while you're talking. Add to that a small but noticable delay, and you have to resort to long pauses between sentences to ensure you don't talk over one another.
Am I the only one that notices this? It's AWFUL compared to what it was like 20 years ago.
MadCow.
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I totally agree. I've basically had it with cell phone voice quality. Sometimes I use Skype and I usually say something like "Hey this sounds just like phones did back in like 1985" and I get all nostalgic for Star Wars, ALF, and (strangely) the Reagan administration.
I went most of this decade using a cell phone, and after my GF got a landline at her new apartment, I decided to get one at mine as well. I found that roughly 30% of the conversation on cell phones is one party asking the other "can you repeat
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I haven't had this problem on a wired phone in the US, even with digital signaling in between. The
POTS beats wireless (Score:2)
"Call quality is reasonable but leaves a lot to be desired."
If you think call quality is inadequate on Plain Old Telephone Service, have you ever tried using wireless phones? On POTS we used to commercials that promised "you can hear a pin drop". Now it's "can you hear me now?"
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.
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And don't forget that you could use the handset to beat an attacker to death without dropping the call you were on!
And there's a good reason for that (Score:3, Informative)
Even in the dawn of telephony, frequency response was a significant issue. Besides the poor quality of transducers, the lines themselves weren't very good. Twisted pairs would have been nice, but early telephone wasn't twisted to improve common-mode rejection, it was twisted to keep the pairs together. Common residential service used something approaching zip cord from about 1960 on, maybe earlier. This isn't even twisted. You wonder why your DSL service is so crappy? I wonder how it even works at all. 10Base-T would barf on 30 feet of straight-line zip cord, and there is a good chance your house has 60-80 feet of it from the pole to the NT1. My first ISDN service at home was a fiasco, with load coils and conditioners being ripped out and new cable strung from the street to the complex demarc.
Frequency response is not the same thing as bandwidth (though they are directly related), but for telephone a 300-3300Hz response is intelligible and manageable. Doubling it to 6500Hz doesn't do a whole lot except consume bandwidth and marginally improve intelligibility. If you want fidelity, well, 12,500Hz is a good start. A loty of people never heard the flyback transformer on their old TVs vibrate, but I can hear them loud and clear. That's 15,750Hz.
And AM radio can sound very, very good. AM in America has a theoretical response of 16KHz, but currently is restricted in the U.S. to 10.2KHz (since 1989) to accomodate more stations and reduced interference from distant stations. The BBC at one time sent good audio, and a few shortwave stations did, and old AM radios had great speakers because they sent pretty good audio back then. Reducing response is also a way to extend range, along with compression, limiting, and a few other tricks that degrade ausio quality greatly. But AM is now the province of talk and news, so it doesn't seem to matter. FM, of course, also uses those tricks, and the result is nasty sound quality. To a generation broguth up on 128kbps MP3s, this is not a great loss. I code my music for my players at 320K or any of the lossless formats. 128k sizzle drive me crazy. And most FM music stations use MP3s anyways, they are largely programmed nationally and delivered over a satellite link. Tragedy.
To ask for improved sound quality in telephone is to ask for some compromises - fewer conversations over a given link, fewer conversations per cell tower, more Internet bandwidth. I'm pretty sure none of the incumbents will bother, as this ultimately results in increased direct costs, and probably zero increased revenue. Skype, etc., play with the codec and give apparently better results, the emphasis on 'apparently'. There are some clever audio tricks that will give a more pleasing experience with very little increase in bandwidth. Maybe Android can play with the audio, but I bet Apple could care less. The ILECS, bah!
So, the legacy of telephony is an old one, and has left us with something that works, but not as well as it could. Just a few more dollars, and you could have better!
engineered (Score:2, Informative)
The bandwidth was not "accepted". It was set by the engineers that design the first analog telephone systems. It is a compromise between the need to have very small bandwidth per channel (so you can multiplex a lot of channels, and send them on the expensive long-distance cable) and the need to understand what the other person is saying and also, very important, to recognize who that person is (large bandwidth is better). They made s
Telephones and Mic's (Score:3, Insightful)
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They'd better, or by God I'll go over there and finish what the Revolutionary war started!
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They'd better, or by God I'll go over there and finish what the Revolutionary war started!
America?
Re:Pardon me, but... (Score:4, Funny)
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My youngest brother was nicknamed "boff" at school in the 90s.
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Sometimes. Probably depends on when/where a given person was born. Seems a bit more common amongst older folks who were born in the countryside.
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I've got this gold plated, vacuum tube telephone cable that will fix all your problems. It normally retails for $1,000 but I'll give you a discount and sell it at $750.
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It's not just you and it's not because you grew up in a Hi-Fi world. I grew up in an environment listening to AM and SSB transmissions, and I have a hard time processing sounds, but at the same time I can hear the sounds just not understand them.
When I watch TV and have the audio coming through the TV speakers I'll turn on CC just to understand what's happening. If I feed the audio through the external receiver/dvd player/surround sound it makes it much easier to understand the dialog.
I've been accused ma
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