Miscellaneous Standards

 

ITU V Standards[1]

V.1     Defines bits as mark/space voltage levels

V.2     Power levels for modems signals over telephone loops

V.3     International Alphabet  No. 5

V.4     The data frame - The general structure of V.5 signals

V.5     Synchronous signaling rates for dial-up lines

V.6     Synchronous signaling rates on leased lines

V.7     A list of modem terms in English, French, and Spanish

V.10   Unbalanced high speed interfaces [RS-423]

V.11   Balanced high speed interfaces [RS-422]

V.14   Asynchronous to synchronous conversion

V.15   Telephone acoustic couplers

V.16   Medical analog data modems

V.17   Group 3 fax modulation. Two wire, half-duplex, trellis coded, 7200, 9600, 12000, & 14400 bps.

V.19   DTMF modems

V.20   Parallel data modems in the PSTN

V.21   300 bps FSK modem [Bell 103]

V.22   1200 bps [600 baud] FSK modem [Bell 112A]

V.22bis QAM 2400 bps modems with 1.2 Kbps fallback

V.23   600/1200bps FM modem with a 75 bps reverse channel. Used on some videotext systems

V.24   Defines the interface between DCE and DTE. Equivalent to functional part of EIA RS-232C

V.25   Automatic calling and answering equipment with manual enabling of echo suppression.

V.25bis  Bit synchronous auto-dialing protocol. Equivalent to the Hayes AT commands

V.26   2400 bps [1200 baud] 4 wire full duplex PSK modem

V.26bis  2400 bps [1200 baud] half duplex PSK modem usable over the switched network.

V.26terbo 2400/1200 bps [1200 baud] PSK full duplex modem

V.27   4800 bps [1600 baud] PSK modem

V.27bis 4800/2400 [1600/1200 baud] PSK modem. Usable on leased circuits.

V.27terbo 4800/2400 PSK modem used for half duplex Group 3 fax at 1600/1200 baud. Used on the switched network.

V.28   Defines the electrical characteristics of V.24 or RS-232

V.29   9600/7200/4800/ [2400 baud] PSK/QAM modem. Often used for Group 3 fax over the switched network.

V.31   Electrical characteristics for single circuit interexchange circuits controlled by contact closure.

V.32   9600/4800 [2400 baud] QAM full duplex modem using trellis coding and echo cancellation. Used over the switched network.

V.32bis 4800/7200/9600/12000/14400 [2400 baud] TCQAM full duplex modem using trellis coding, echo cancellation, and automatic rate adaptation. This is a very popular modem for PCs.

V.32terbo 14400/16800/19200 [2400 baud] TCQAM full duplex modem using trellis coding, echo cancellation, and automatic rate adaptation.

V.32fast The informal name for an unfinished standard that may be renamed V.34 when ratified. It may replace the V.32bis with speeds up to 28800 bps, it may also be the last analog protocol.

V.33   14400 bps [2400 baud] TCQAM 4 wire full duplex modem

V.34   The ratified version of V.32fast. It is expected to provide speeds up to 128 Kbps [3429 baud]

V.35   48 Kbps data transmission over 60 - 108 KHz group band circuits.

V.36   Specialized multi line 48000 bps modem over 60 - 108 KHz group band circuits

V.40   Electromechanical equipment error indication.

V.41   Code-independent error control system.

V.42   Defines the two stage detection and negotiation of LAPM error control, enabling 19.2 Kbps transmission over dial-up lines.

V.42bis Extends V.42 to include data compression

V.50   Sets the standard for data transmission quality over telephony circuits

V.51   Maintenance requirements for international data circuits

V.52   Measurement equipment for data distortion and error rates

V.53   Impairment limits for data circuits

V.54   Modem loop testing devices

V.55   Impulse noise measurement

V.56   Comparative modem testing procedures

V.57   High speed data transmission test equipment

V.100  Interconnection techniques between PDNs and PSTNs

ITU X Standards[2]

X.1     International PSTN service classifications

X.2     International PDN user facilities

X.3     PDN packet assembly/disassemby

X.4     International Alphabet 5 PDN code structure

X.20   PDN DTE/DCE data interface requirements

X.20bis  V.21 compatible DCT/DCE PDN interface

X.21   General purpose synchronous PDN DCT/DTE interface

X.24   Interexchange circuit definitions on the PDN DCT/DCE interface

X25     PDN packet mode DTE/DCE data interface requirements

X.26   Unbalance interexchange circuit electrical characteristics

X.27   Unbalance interexchange circuit electrical characteristics

X.28   DTE/DCE interface for national PDN PAD facilities

X.29   Control and user data proceedures between DTE and PAD

X.30   Standardization of basic model page-printing machine in accordance with International Alphabet 5

X.31   Transmission interechange between 200 baud DTE/DCE

X.32   Answerback units for 200 baud start stop machines

X.33   Margine measurement of start stop machines

X.40   FSK standards over FDM groups

X.50   International synchronous data networks

X.51   10 bit international synchronous data networks

X.60   CCS for synchronous data

X.70   Terminal and transit control signaling on international asynchronous circuits

X.71   Terminal and transit control signaling on international synchronous circuits

X.75   Terminal and transit control signaling on international packet switched data networks

X.92   Hypothetical reference connections for public synchronous data networks

X.95   PDN network parameters

X.96   PDN call progress signals

X.121  PDN international numbering plan

CCITT Modem Summary

Modem

Modulation

bps

Baud

Comments

V.17

QAM

7200-14400

7400

 

V.21

FSK

300

300

Full Duplex - Bell 103

V.21bis

QAM

2400

600

Full Duplex

V.22

4 - DPSK

1200

600

Full Duplex

V.22 bis

QAM

2400

600

Full Duplex - Bell 212A

V.23

FM

1200/75

2100/1300 & 450/390

75 bps reverse channel

V.26

4 - DPSK

2400

1200

Full Duplex

V.26bis

PSK

2400

1200

Half Duplex

V.26terbo

PSK

2400/120

1200

full duplex

V.27

PSK

4800

1600

 

V.27bis

PSK

1600/1200

 

 

V.27terbo

PSK

4800/2400

1600/12

Group 3 fax

V.29

PSK/QAM

9600/7200/4800

2400

Group 3 fax

V.32

QAM

9600/48

2400

Full Duplex

V.32bis

TCQAM

4800-14400

2400

 

V.32terbo

TCQAM

14400-19200

2400

 

V.32fast

TCQAM

to 28800

to 3429

 

V.33

TCQAM

14400

2400

 

V.36

 

48000

 

Group line modem

V.37

 

72000

 

Group line modem

 

Basic Interfaces

RS232

This North American standard enjoys wide popularity, for interconnecting devices which are located within approximately 20 meters of each other.

Standard bearer:       EIA

European equivalent: V.28

Typical 1 level:         -5 to -15 volts

Typical 0 level:         5 to 15 volts

Maximum bit rate:     20 Kbps

Pin

Designation

Direction

Comments

1

AA

Bidirectional

Chassis Ground

2

BA

to DCE

Transmit DATA

3

BB

to DTE

Received DATA

4

CA

to DCE

Request to Send

5

CB

to DTE

Clear to Send

6

CC

to DTE

Data Set Ready

7

AB

Bidirectional

Signal Ground

8

CF

to DTE

Carrier Detect

9

 

 

 

10

 

 

 

11

 

 

 

12

SCF

to DTE

Secondary Received Signal Detector

13

SCB

to DTE

Secondary Clear to Send

14

SBA

to DCE

Secondary Transmit DATA

15

DB

to DTE

DCE Timing

16

SBB

to DTE

Secondary Received DATA

17

DD

to DTE

DCE Receiver Timing

18

 

 

 

19

SCA

to DCE

Secondary Request to Send

20

CD

to DCE

Data Terminal Ready

21

CG

to DTE

Signal Quality Detector

22

CE

to DTE

Ring Indicator

23

CH/CI

Bidirectional

Data Signaling Rate Selector

24

DA

to DCE

DTE Transmitter Timing

25

 

 

 

 

 



[1]         Modem Communications Standards, Stephen J Bigelow, Electronics Now, September 1994

[2]         Datacom Networking Video Cookbook Number 8, Telebyte Technologies Inc.