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CCITT draft recommendation T.4 (RFC0804)

IP.com Disclosure Number: IPCOM000003853D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 8 page(s) / 17K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

International Telegraph and Telephone Consultative Committee of the International Telecommunication Union: AUTHOR

Abstract

SOURCE: DRAFTING GROUP ON DRAFT RECOMMENDATION T.4 TITLE: DRAFT RECOMMENDATION T.4 - STANDARDIZATION OF GROUP 3 FACSIMILE APPARATUS FOR DOCUMENT TRANSMISSION (as amended and agreed by Working Party XIV/2)

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RFC 804

CCITT Draft Recommendation T.4

As Defined In: CCITT STUDY GROUP XIV, CONTRIBUTION No.25-E

SOURCE: DRAFTING GROUP ON DRAFT RECOMMENDATION T.4

TITLE: DRAFT RECOMMENDATION T.4 - STANDARDIZATION OF GROUP 3

FACSIMILE APPARATUS FOR DOCUMENT TRANSMISSION (as

amended and agreed by Working Party XIV/2)

Draft Recommendation T.4

STANDARDIZATION OF GROUP 3 FACSIMILE APPARATUS FOR DOCUMENT

TRANSMISSION

The CCITT, considering

a. that Recommendation T.2 refers to Group 1 type apparatus

for ISO A4 document transmission over a telephone-type

circuit in approximately six minutes;

b. that Recommendation T.3 refers to Group 2 type apparatus

for ISO A4 document transmission over a telephone-type

circuit in approximately three minutes:

c. that there is a demand for Group 3 apparatus which

enables an ISO A4 document to be transmitted over a

telephone-type circuit in approximately one minute;

d. that for a large number of applications black and white

reproduction is sufficient;

e. that such a service may be requested either

alternatively with telephone conversation, or when

either or both stations are not attended; in both cases,

the facsimile operation will follow Recommendation T.30,

(unanimously) declares the view that Group 3 facsimile

apparatus for use on the general switched telephone network

and international leased circuits should be designed and

operated according to the following standards:

1. Scanning track

The message area should be scanned in the same

direction in the transmitter and receiver. Viewing the

message area in a vertical plane, the scanning direction

should be from left to right and subsequent scans should be

adjacent and below the previous scan.

2. Dimensions of apparatus

CCITT Draft Recommendation T.4 PAGE 2

The following dimensions should be used:

a. A normal definition standard and an optional higher

definition standard of 3.85 and 7.7 line/mm respectively

in vertical direction;

b. 1728 black and white picture elements along the scanned

line;

c. A scanning line length of 215 mm. Other scanning line

lengths may be employed in which case the scanning

density should be changed to maintain the correct

picture proportions;

d. Input documents up to a minimum of ISO A4 size should be

accepted.

3. Transmission time per scanning line

A total scanning line is defined as the sum of DATA

bits plus any required FILL bits plus the EOL bits. The

minimum t...