It's amazing that modem speeds reached 56Kb/s over analog lines that were digitized at 64Kb/s. Especially since T1 carrier systems stole one low-order bit in every other sample for control purposes. That's an incredible accomplishment of signal processing. As late as the mid-1970s, it was believed to be theoretically impossible. Bell Labs once did a study that concluded that 19Kb/s was the upper limit for analog phone lines.
It's also impressive that the modem negotiation process worked as well as it did, across many vendors and generations of modems.
When the modems agree on a good high-speed mode, the data sounds like white noise. That's proper. Any modulation scheme which doesn't sound like white noise is wasting bandwidth. Carriers and tones waste energy but carry no payload data.
This, incidentally, is a critique of SETI. For a long time, the SETI crowd was looking for "carriers", signals with a big fixed-frequency component. Carriers are obsolete. Other than legacy analog broadcast stations, almost nothing with high power today transmits a strong carrier signal. So SETI was looking for civilizations that used high power analog radio.
In my first year of university I used dial-up to connect from home. The university had a mixture of 14.4Kbps and 28.8Kbps modems all tied into the same phone number, so it was random which kind you got. Obviously, doubling your data rate in those days was easily worth hanging up and trying again as many times as it took! The handshaking sound of the two types of modems the university was using were audibly distinct, so you could hang up and try your luck again immediately if you heard a 14.4K modem handshake. Listening was much quicker than waiting for the handshake to finish and then testing the download rate.
So, why did a 14.4Kbps modem handshake sound different from a 28.8Kbps modem handshake? The scrambled data test phase seems to be a likely culprit, because modems with different capabilities should sound different in this phase. There are plenty of 14.4Kbps modem recordings on youtube, but I couldn't find a 28.8Kbps handshake recording to do a proper comparison! It might also be that different brands or models of modems could be distinguished from one another before they even got to the scrambled data test.
I always thought its kind of funny that everyone believed this to be true when in reality you could just deactivate the sound in the driver settings. Which I did pretty much immediately, but nobody I knew ever even thought of.
Its a perfect example for the fact that most people will never ever change the default settings.
I liked hearing the sounds. I could tell just from the connection sounds what speed I connected at. If my modem was falling back below 33k frequently, especially below 28k, then I knew something was wrong.
It's also a great example of a terrible default, and why it's important to think about what the default should be. I'm sure the guys designing it were like "Well, people will want to hear this, so they can tell if something is going wrong." In reality, the modem noise is the opposite of what anyone ever wanted to hear, ever.
the modem noise is the opposite of what anyone ever wanted to hear, ever.
Speak for yourself. Not only is it music to a nerds ear, but it also provided useful information (line busy, handshake problem, connection speed, sysops mom picked up the phone) long before the modem itself would report back.
Given that auto redial was also a popular default, having the speaker on is important so you know when you've dialed a person instead of a computer. A terrible default would have been having the modem speaker be on for the duration of the call, and not stop once the handshake is done.
The fake noise thing in electric cars bugs the hell out of me. I've got an aging Honda Element extremely loud tires. I want my next car to be as quiet as possible.
Amazing I remember the "tune" that the modem makes from back in the day but never realized how much stuff was going on. I never knew a custom connection was being made each time, but I guess that makes sense as not all phone connections are equal. Has anyone tried to use a dial up model recently? Do the telephone lines still support it, or has anything changed on the exchanges that would stop a modem working?
Apparently still alive and well in some circles (agree with below that most uses are financial/credit/legacy apps). I worked at one of the largest developers of ISP modem infrastructure in the late 90's called Ascend. Company was purchased by Lucent. Just a few years ago I ran into a friend still with the company and mentioned that, globally, carriers were still installing new dial-up infrastructure to the tune of a few $100-million annually. Amazing.
A lot of lines here in Australia will still support it (some at only ~31.2kbit due to copper quality) but when you sign up to ADSL you can order a "naked" service with no dialtone, which can be cheaper in some cases - there'll be no dialup fallback if you do that, though.
Remembers me of this funny anekdote: there were a whole lot of 56k6 modems out there that had this bug, where they would parse the +++ATH0 (hangup) command, over plain text connections. So when I sent that into a huge IRC channel.. You could see over a hundred connections all being quit; with reason 'EOF from client.'
Many rejoined with stuff like
#Appears as ANNA.
From MS Comic Chat. Good old days!
It wasn't quite like that (at least in the usual cases). You had to do something that would get the other end to send it back out again, such as putting it in a ping payload.
The reason for the "bug", if I'm remembering correctly, is that Hayes or US Robotics or some company like that had a patent on the guard times that were supposed to surround the +++.
I remember having to whistle at the right tone down an acoustic coupler to get carrier to pick up (110 and 300 baud) as we where a long way from the exchange.
I know these sounds very well.. I ran a BBS for many years in another life, and left the modem sound on (probably to just irritate my parents). I could identify a connection "speed" from the sounds, but I never really knew what was going on, other than some high-level idea of initialization. Cool to see this.
In this link http://youtu.be/vvr9AMWEU-c you can hear an additional sound pattern at the end that is not explained in the article or the image, but I remember hearing it every time I connected via modem. Can someone explain what it is?
That extra twangy bit means the modems negotiated a V.92[1] connection instead of a v.90 connection. Just a newer protocol, that was a bit faster, but required cleaner phone lines to negotiate successfully.
I spent 6.5 years of my life working technical support for a dial-up ISP. Listening to the handshake (when the user had two phone lines so they could attempt a connection with us on the line to listen) was a valuable diagnostic tool.
I had some cheapie external modem that didn't have a full AT command set for some reason, ended up physically soldering a switch between the speaker and the rest of the circuit to mute/unmute it.
It's also impressive that the modem negotiation process worked as well as it did, across many vendors and generations of modems.
When the modems agree on a good high-speed mode, the data sounds like white noise. That's proper. Any modulation scheme which doesn't sound like white noise is wasting bandwidth. Carriers and tones waste energy but carry no payload data.
This, incidentally, is a critique of SETI. For a long time, the SETI crowd was looking for "carriers", signals with a big fixed-frequency component. Carriers are obsolete. Other than legacy analog broadcast stations, almost nothing with high power today transmits a strong carrier signal. So SETI was looking for civilizations that used high power analog radio.