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1、 TIA STANDARD ANSI/TIA-825-A-2003 Approved: April 16, 2003 A Frequency Shift Keyed Modem for Use on the Public Switched Telephone Network TIA-825-A (Revision of TIA/EIA-825) APRIL 2003 TELECOMMUNICATIONS INDUSTRY ASSOCIATION Representing the telecommunications industry in association with the Electr
2、onic Industries Alliance Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- NOTICE TIA Engineering S
3、tandards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product fo
4、r their particular need. The existence of such Standards and Publications shall not in any respect preclude any member or non-member of TIA from manufacturing or selling products not conforming to such Standards and Publications. Neither shall the existence of such Standards and Publications preclud
5、e their voluntary use by Non-TIA members, either domestically or internationally. Standards and Publications are adopted by TIA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, TIA does not assume any liability to any patent owner, nor does it assume
6、 any obligation whatever to parties adopting the Standard or Publication. Further details of the development process are available in the TIA Engineering Manual, located at http:/www.tiaonline.org/standards/sfg/engineering_manual.cfm This Standard does not purport to address all safety problems asso
7、ciated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (From Standards Proposal No. 3-4628-RV1, formulated u
8、nder the cognizance of the TIA TR-30.1 Subcommittee on Modems.) Published by TELECOMMUNICATIONS INDUSTRY ASSOCIATION 2003 Standards and Technology Department 2500 Wilson Boulevard Arlington, VA 22201 U.S.A. PRICE: Please refer to current Catalog of TIA TELECOMMUNICATIONS INDUSTRY ASSOCIATION STANDAR
9、DS AND ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada (1-800-854-7179) International (303-397-7956) or search online at http:/www.tiaonline.org/standards/search_n_order.cfm All rights reserved Printed in U.S.A. Copyright Telecommunications Industry Association Provided
10、 by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- NOTICE OF DISCLAIMER AND LIMITATION OF LIABILITY The document to which this Notice is affixed (the “Documen
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21、SIBILITY OF SUCH DAMAGES. THE FOREGOING NEGATION OF DAMAGES IS A FUNDAMENTAL ELEMENT OF THE USE OF THE CONTENTS HEREOF, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS. Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Empl
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23、y Association. For information consult our website at http:/www.tiaonline.org/about/faqDetail.cfm?id=18 Organizations may obtain permission to reproduce a limited number of copies through entering into a license agreement. For information, contact: Global Engineering Documents 15 Inverness Way East
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25、r networking permitted without license from IHS -,-,- FOREWORD (This foreword is not part of this Standard) This Standard was formulated under the cognizance of TIA Subcommittee TR-30.1 Modems. This Standard specifies a Frequency Shift Keyed (FSK) modem operating at a data signaling rates of 50 and
26、45.45 symbols/sec. The deaf and hard of hearing generally use this modem for real time 2-way text based communication over the public switched telephone network. i Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Be
27、rnie Not for Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- This page intentionally left blank ii Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not fo
28、r Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA-825-A A FREQUENCY SHIFT KEYED MODEM FOR USE ON THE PUBLIC SWITCHED TELEPHONE NETWORK 1 SCOPE This standard specifies a FSK modem which operates at a nominal data signalling rates of 50 or 45.4
29、5 symbols per second over the switched telephone network. 2 NORMATIVE REFERENCES TIA-232-F-1997 Interface Between Data Terminal Equipment And Data Circuit Terminating Equipment Employing Serial Binary Data Exchange. TIA-968-A-2002 Telecommunications, Telephone Terminal Equipment, Technical Requireme
30、nts for Connection of Terminal Equipment To the Telephone Network. TIA/TSB121 Cellular Subscriber Unit Interface for TDD 3 DEFINITIONS 3.1 Frequency Shift Keying (FSK) - a transmission method where a signal is applied to the line in response to the pressing of a key (or the electronic equivalent). 3
31、.2 TTY - A term used by the deaf and hard of hearing for a device which incorporates a FSK modem such as described in this standard. This term originates with the electromagnetic Teletypewriters originally used for this communications. 4 Line Signal 4.1 Transmission Mode The transmission mode is cha
32、racter oriented Frequency Shift Keying (FSK) using two tones to represent the asynchronous serial data. A binary ONE is represented by 1400 Hz 1% tone and a binary ZERO is represented by 1800 Hz 1%tone (see Annex B). 4.2 Bit duration A bit duration of 20.00 or 22.00 0.40 ms providing nominal data si
33、gnalling rates of 50 or 45.45 symbols/s respectively. 4.3 Character Set The character set conforms to the 5-bit Baudot set (see Annex A). Characters are preceded by a start bit (binary ZERO) and followed by a stop bit (binary ONE). The start bit shall be one bit time in duration. It is desirable tha
34、t the stop bit be 1.5 bit times in duration.(see Note 1) Each key depression causes the transmission of a complete Baudot character including start and stop bits. A binary ONE hold tone also follows the last key depression. In this case the hold tone is transmitted for a period of 150 ms to 300 ms a
35、fter the end of the stop bit(s). Notes: 1 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA-825
36、-A 1 Designers should be aware that existing equipment in the field may provide stop bit durations of anywhere from 1 to 2 bit times. 2 The transmitter and receiver should normally start up in the LTRS mode. Additionally, to minimize error propagation, the DCE should re-send the most recent (i.e. la
37、st sent) mode character (i.e., LTRS or FIGS) at least every 72 characters. 4.4 Bit Ordering The bit ordering is LSB first with the first data bit corresponding to the Least Significant Bit (LSB) and the fifth data bit to the Most Significant Bit (MSB) 4.5 Transmit Levels When directly connected to t
38、he network (see section 5.2.1) the transmit levels shall be in conformity with TIA-968-A. When acoustically coupled to the telephone network the level is typically 108 6 dBSPL. 4.6 Transmit capability The transmitter shall be capable of transmitting regardless of the state of the receiver. 5 INTERFA
39、CES 5.1 DTE-DCE Interface The DTE-DCE interface shall support the following circuits (or their logical equivalent) as specified in ANSI/TIA/EIA-232-F-97: Table 1 -Supported DTE-DCE Interface Circuits ITU-T V.24 Number Circuit Description 103 BA Transmit Data 104 BB Received Data 135 CK Received Ener
40、gy Present 5.2 Line Interface 5.2.1 Direct Connection When the DCE is directly connected to the switched telephone network (land line) the DCE shall provide a jack in conformity with TIA-968-A. 5.2.2 Acoustic Interface The DCE may be equipped with an Acoustic interface, the characteristics of which
41、are beyond the scope of this standard. 5.2.3 Wireless Interface When the DCE is connected to a wireless phone the interface shall conform to TSB-121. 2 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for
42、 Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA-825-A Annex A (Informative) Table A.1 - Baudot Codes DEC HEX BINARY LETTER FIGURE 0 00 00000 backspace backspace 1 01 00001 E 3 2 02 00010 LF LF 3 03 00011 A - 4 04 00100 Space Space 5 05 00101
43、 S 6 06 00110 I 8 7 07 00111 U 7 8 08 01000 CR CR 9 09 01001 D $ 10 0A 01010 R 4 11 0B 01011 J 12 0C 01100 N , 13 0D 01101 F ! 14 0E 01110 C : 15 0F 01111 K ( 16 10 10000 T 5 17 11 10001 Z “ 18 12 10010 L ) 19 13 10011 W 2 20 14 10100 H = 21 15 10101 Y 6 22 16 10110 P 0 23 17 10111 Q 1 24 18 11000 O
44、 9 25 19 11001 B ? 26 1A 11010 G + 27 1B 11011 FIGS FIGS 28 1C 11100 M . 29 1D 11101 X / 30 1E 11110 V ; 31 1F 11111 LTRS LTRS Note: CR and LF may be manually or automatically generated by the DTE. If automatic generated, the sequence may contain an extra (non-printable) character to provide adequat
45、e time for older electromechanical TTYs to respond. CR & LF are inserted into the transmitted characters after a maximum of 72 characters to allow for the carriage return of older electromechanical TTYs. 3 Copyright Telecommunications Industry Association Provided by IHS under license with EIALicens
46、ee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/30/2007 19:57:36 MDTNo reproduction or networking permitted without license from IHS -,-,- TIA-825-A 4 Annex B (Informative) B.1 Receiver Frequency Tolerance The Transmitter tolerances on existing devices in the field may vary as much
47、 as 4% from the nominal values specified in Section 4.1, therefore receivers should be designed to accommodate these variations to ensure interworking with the broadest range of terminals. B.2 Receiver Stop Bit Tolerance A receiver should be capable of decoding characters with stop bits of anywhere
48、from 1.0 to 2.0 bit times in length. B.3 Receiver Signal Level Tolerance A receiver should be capable of correctly decoding the following message, or its equivalent, for at least 120 seconds, with receive levels from 5 dBm to 45 dBm and a signal to noise ratio of 13 dB. THE QUICK BROWN FOX JUMPED OVER THE LAZY DOGS 123456789 TEST Copyright Telecommunications Industry Association Provided by IHS under license with EIALicensee=IHS Employees/1111111001,