Serial Speeds

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Note: these table list rates in bits per second. For asynchronous speeds at or below 600 bps and all synchronous speeds listed, this number is also the same as the baud (not "baud rate"). For other speeds, the bits/second figure and the baud may or may not be the same: it depends upon the encoding used to carry the signal.

The term "baud" means "symbols per second" and is already a rate. In normal operations, the "baud rate" should therefore always be zero, thus indicating that signalling is happening at a constant speed. The "baud rate" will be non-zero at the times when signalling is starting, stopping, changing encodings, or changing rates.

Asynchronous Speeds

bits/secnotes
5 (approx)professional Morse Code
45.45WWII era Radio TTY (aka RTTY)
60Baudot
75Baudot
110TTY33; the old standby
134.5IBM Selectrics
135same as above
150 
200 
300"it's so much faster than 110..."
600 

Except for Bell 202A format (the 1200 bps one that no one used much; although it is now used for caller ID signalling), speeds above 600 bps are communicated at 600 baud, with multiple bits per symbol.

bits/secnotes
1 200"boy, this is really fast..."
1 800 
2 400the speed modem that every machine came with after 9600 was available...
3 600 
4 800 
7 200 
9 600"at last, fast enough!"
14 400but then came...
19 2002 x 9 600
28 800fastest base signal rate on a phone line
38 4004 x 9 600, popular RS-232 and modem speed
56 0006 x 9 600, popular modem speed
57 600popular RS-232 speed
115 2004 x 28 800

Synchronous Speeds

bits/secnotes
8 000voice channel sample rate
56 000US DS0
64 000European DS0; ISDN B channel
128 0002 x 64 000; 1/12 T1
144 000ISDN 2B+D channel
192 0003 x 64 000; 3/24 T1
230 400AppleTalk LocalTalk
256 0004 x 64 000; 1/6 T1, AC-3 stereo
320 0005 x 64 000; 5/24 T1
384 0006 x 64 000; 1/4 T1, AC-3 5.1 sound
448 0007 x 64 000; 7/24 T1
512 0008 x 64 000; 1/3 T1
576 0009 x 64 000; 3/8 T1
640 00010 x 64 000; 5/12 T1
704 00011 x 64 000; 11/24 T1
768 00012 x 64 000; 1/2 T1
832 00013 x 64 000; 13/24 T1
896 00014 x 64 000; 7/12 T1
960 00015 x 64 000; 5/8 T1
1 000 000Corvus Omninet data rate
1 024 00016 x 64 000; 2/3 T1
1 088 00017 x 64 000; 17/24 T1
1 152 00018 x 64 000; 3/4 T1
1 216 00019 x 64 000; 19/24 T1
1 280 00020 x 64 000; 5/6 T1
1 344 00021 x 64 000; 7/8 T1; also 24 x 56 000
1 408 00022 x 64 000; 11/12 T1
1 411 200CD data rate (44 100 samples/sec, 16 bits/sample, 2 channels)
1 472 00023 x 64 000; 23/24 T1
1 536 00024 x 64 000; T1[*]; IDSN Primary
1 544 000DS1; T1 + 8 000 bps signaling
1 546 000unchannelized DS1
2 048 000E1 (European DS1)
3 000 000original Ethernet data rate
4 000 0004 Mbit token ring data rate
4 500 00060:1 compress components NTSC video
6 176 0004 x DS1; DS2
10 000 000Ethernet data rate
12 000 000USB 1.0 signaling rate
16 000 00016 Mbit token ring data rate
34 368 000E3
43 232 0007 x DS2; 28 x DS1
44 736 0007 x DS2; 28 x DS1 + overhead; DS3
51 840 000OC-1 / STS-1
100 000 000FDDI data rate; FastEthernet
115 000 0008-bit NTSC video
135 000 0003 x DS3 + signaling
155 520 000OC-3 / STS-3
270 000 00010-bit SDI component video
466 560 000OC-9 / STS-9
622 080 000OC-12 / STS-12
800 000 000FireWire 800 signaling rate
933 120 000OC-18 / STS-18
1 000 000 000GigaBitEthernet
1 244 000 000OC-24 / STS-24
1 866 000 000OC-36 / STS-36
2 488 000 000OC-48 / STS-48
4 976 000 000OC-96 / STS-96
9 953 000 000OC-192 / STS-192
10 000 000 00010G Ethernet

[*] "T1" officially refers to the physical hardware used to transport the signal over copper lines. The term "DS1" should be used to refer to the signal itself. People, being people, could care less about such details and the terms "T2" and "T3" have crept into use. But it stops there as the whole system shifts over to the OC/STS naming.

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I am Craig A. Finseth.

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Last modified Monday, 2010-07-26T19:49:57-05:00.