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56k modems relied on digital trunk lines
131–140 of 143 posts
Re: 56k modems relied on digital trunk lines
#132Earlier quoted context omitted.
I had 1.5 Mbps DSL in 1999, and I think nearly all of my co-workers either had that or a cable modem with similar speed. I think T1s were like 5x the price for the same download speed.
What market did you have 1.5mbit dsl in, in 1999? GTE in LA county offered 768k/768k symmetric. In 1999. I can't remember when that was increased, but it was after GTE got bought out.
Calgary. I remember it being asymmetric, probably 256 or 512 up.
Re: 56k modems relied on digital trunk lines
#133I remember the day we got 56K from our ISP. Our modem was 56K (no idea what model, some internal WinModem), but the ISP was limited to 33.6K. Then one day, the connection screech sounded different, and I excitedly pointed this out. Several seconds later, it connected, and lo and behold, we had 66% faster downloads.
The fact that all of this worked continues to amaze me, but then, so do mobile phones. I understand at a high level how CDMA works, but it’s just so insane…
Re: 56k modems relied on digital trunk lines
#134Earlier quoted context omitted.
What market did you have 1.5mbit dsl in, in 1999? GTE in LA county offered 768k/768k symmetric. In 1999. I can't remember when that was increased, but it was after GTE got bought out.
Calgary. I remember it being asymmetric, probably 256 or 512 up.
Cadvision? 3mbps cable (sadly Rogers) wasn't impossible at the time.
Re: 56k modems relied on digital trunk lines
#135Re: 56k modems relied on digital trunk lines
#136Earlier quoted context omitted.
Cadvision? 3mbps cable (sadly Rogers) wasn't impossible at the time.
Nucleus!
You know they're still around... somehow? :| The website makes their age clear: https://www.mynucleus.ca/
Re: 56k modems relied on digital trunk lines
#137Earlier quoted context omitted.
Why do 96 or 128khz sampled audio files sound better than 48khz ones? I blind tested and could always tell the difference between them, but not between 128 and 192
Typically, high sampling rate files are part of a different mastering process than what is published as a 44.1kHz cd audio or 48kHz dvd audio. Also, you might possibly be sensitive to resampling artifacts if your output device runs at 44.1kHz and your file is 48kHz or vice versa. Audio testing is hard, and testing on yourself is tricky... But if you have a sample that you're convinced sounds better at high rates than…
> If the rate isn't an even multiple, it's worth using a tool that can dither; dithered resampling artifacts are less abrasive than undithered...
This seems to be mixing up two things; proper interpolation and dithering.
If you have limited bit depth (in practice, 16 bits or worse), you should pretty much always dither, ideally also noise shape. This is independent of the interpolation you're using; having a rational relationship between the original and downsampled signal makes some of the implementation a bit easier, but even for something like 48000 -> 24000, you'll end up with effectively a float signal that you need to convert to your chosen bit depth somehow, and that should be done better than just truncating/rounding.
And even for interpolating between two prime rates, or even variable-rate interpolation, you can and should get great interpolation (typically by picking out polyphase filtering coefficients from a windowed sinc of some sort).
Re: 56k modems relied on digital trunk lines
#138Earlier quoted context omitted.
All the early metropolitan or long-haul fiber (mostly SONET) networks were digital aggregations of various circuit-modes (DS*) in those days. It made sense since the phone network was pretty much the only long haul network around and even the pure-IP networks didn't yet have enough of a market for alternative protocols. I've been out of the core-networking loop for awhile, but my understanding is that most modern lon…
Circuits meant for IP didn't convert digital to analog and back unless they had to share the line with a phone at one end. If you had digital connections to both ends of a digital circuit, you'd use all the bits for data.
I'm a little confused - I didn't say that? I said that a lot of the circuits meant for IP still had to use (digital) protocols designed for voice.
Re: 56k modems relied on digital trunk lines
#139Yup. I worked on the "Rapport" series of switches at Bell Canada. It was DS1 (Digital Signal 1) out one end and a rack full of Zyxel modems on the other side. The idea was RBOCs (Regional Bell Operating Companies) would put these in their CO (Central Office) and terminate 56k modem signals over the analog "last mile" loop to the customer premises and then do Frame Relay over the phone company's data lines to your ISP…
>I know that between around '93 and '97 if you dialed AOL from D/FW there was a good chance your call would be terminated somewhere within a mile or two of your house and the bits flowing between your Compaq Presario and AOL would be sent digitally from the local CO to AOL's data center in Sterling, VA.
Around the end of the dialup era, I noticed a bunch of similar low cost dialup services all used the same phone numbers, is this part of the reason, or were they all just reselling the same internet access or something?
Re: 56k modems relied on digital trunk lines
#140Yup. I worked on the "Rapport" series of switches at Bell Canada. It was DS1 (Digital Signal 1) out one end and a rack full of Zyxel modems on the other side. The idea was RBOCs (Regional Bell Operating Companies) would put these in their CO (Central Office) and terminate 56k modem signals over the analog "last mile" loop to the customer premises and then do Frame Relay over the phone company's data lines to your ISP…
>I know that between around '93 and '97 if you dialed AOL from D/FW there was a good chance your call would be terminated somewhere within a mile or two of your house and the bits flowing between your Compaq Presario and AOL would be sent digitally from the local CO to AOL's data center in Sterling, VA. Around the end of the dialup era, I noticed a bunch of similar low cost dialup services all used the same phone num…
Not GP, but this reminds me of how modern GPON (including XGS-, 50G-) works in some areas, like NBN (Australia), NTT FLETS (Japan) and Openreach (UK) where the fiber runs, on what is essentially, a PPPoE or IPoE pipe that tunnels the connection from the customer to the real ISP the user subscribed. Switzerland (basing at least on Init7 docs) has somehow decided on fiber-optic being a real dumb pipe, which is really nice but I imagine that it is costly.