Internet Data Modems

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Internet Summaries

Modem Speeds Summary Chart

The modem speed chart below lists current and historical modem types, along with their speeds, both in Baud rate, and Byte rate.



Currently, the most popular modems are 56K(dial-up), cable modems, and DSL modems (broadband). The 56K dial-up rate is a maximum rate.

DSL modem speeds are limited by the distance to the Central Office, and the speed should vary little.

Cable modem speeds are limited by the number of users online, and speed can suffer substantial degradation, especially on weekends, when demand is the greatest.

 

Modem Speeds

 

Approx.
Cost
per
Month
 Modulation
Method
Rated
Bits/ Sec.
(Baud Rate)
Rated
Bytes/ Sec.
(baud ÷ 8)
Bytes
per
Minute
Minutes
per
Mega
Byte
Time to download
a 20MB file

Minutes . . . . Hours
Note
 na
 FSK
2,400
300
18,000
56
1111.1
18.5

 Frequency Shift Keying

 na
 FSK
4,800
600
36,000
28
555.6
9.3

 Frequency Shift Keying

 na
DPSK
9,600
1,200
72,000
14
277.8
4.6

 Differential Phase Shift Keying

 na
DPSK
14,400
1,800
108,000
9
185.2
3.1

 

na
DPSK
19,200
2,400
144,000
7
138.9
2.3

 

Obs.
DPSK
28,800
3,600
216,000
4.6
92.6
1.5

v.34

$10
DPSK
33,600
4,200
252,000
4.0
79.4
1.3

v.34

$10
DPSK
56,000
7,000
420,000
2.4
47.6
0.8

v.90 Common "dial-up"

$30
ISDN
128,000
16,000
960,000
1.0
20.8
0.3

Integrated Services Digital Network

$26
DSL
Worst
300,000
37,500
2,250,000
0.4
8.9
0.1

Digital Subscriber Line
Distance to C. Office

$26
DSL
Best
1,544,000
193,000
11,580,000
0.09
1.7
0.0

Limited availability

$42
Cable
worst
300,000
37,500
2,250,000
0.4
8.9
0.1

Cable Modem
Other user traffic

$42
Cable
best
6,000,000
750,000
45,000,000
0.02
0.4
0.0

Limited availability

High End High-speed Modems

$500
T1
1.544M
193,000
11 million
0.1
1.7

 

 

$5K
T3
44.7M
5,592,000
335 million
0.003
0.1

 

 

$50K
ATM
155M
19,375,000
1.1 billion
0.001
0.0

 

 


Cable modems are faster than DSL modems, but seem to have more problems.
DSL speed can be excellent, but sometimes is subject to problems, as well.
At any rate, obtaining modem support frequently can be a problem.
Whether you get good support, or otherwise, is based upon the luck of the draw.
I have not had very good luck.

For instance, Comcast was not able to set up my cable modem - it wouldn't work at all.
NO ONE who works on the problem has the knowledge to fix it -
and there is NOBODY to call who can offer any help.
Just script readers.
There is no "second level support". Even for installation.
Maintain low modem speed expectations until it is working.

So I am stuck with SBC 120K speed DSL, which should be 380K MINIMUM, according to the ADSL specification.
Ahh, but SBC DSL service is Rate Adaptive, which means that however slow your service is,
TOO BAD, that's what you get.
SBC does not believe in QOS compliance (Quality of Service spec).
If your data transfer rate is marginal to poor to bad, you still PAY THE SAME amount.

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This Vaughn's Modem Speeds Summary page was last updated on 2009-01-21.