Specifications For TDD Data Transmit/Receive
 
All TDD manufacturers follow these specs but no tolerance level is given:
 
1.  Acoustic coupling (standard G- and K- type handset)
 
    Input level: 65 dB SPL minimum / 110 db SPL maximum
                                   -4        2
                 (0 dB SPL = 2 x 10   dyne/cm )
 
    Output level: 95 dB SPL minimum / 100 dB SPL maximum
                  (acoustic pressure to produce a -9 dBm
                   signal at the telephone set line terminals
                   on an average loop)
 
2.  Direct modular connection
 
    Connector:  standard 6-position modular jack
 
    USOC No.:   RJ11C
 
    Input level: -50 dBm minimum / 0 dBm maximum
 
    Output level: -13 dBm minimum / -9 dBm maximum
 
3.  Modem
 
    Modulation method:  Frequency Shift Keying
 
    Mark frequency:  1400 Hz +-5 Hz
 
    Space frequency:  1800 Hz +-5 Hz
 
    Signal to noise ratio:  13 dB
 
    Carrier to data delay:  180 ms
 
    Carrier to hold time:  156 ms
 
4.  Protocol
 
    Code:  Baudot
 
    Mode:  Half duplex
 
    Transmissions:  Asynchronous
 
    Start bit:  1
 
    Stop bit:   1
 
    Data bits:  5
 
    Parity:  None
 
    Data rate:  45.5 baud (buffered)
 
Note: The above information is from Plantronics, Inc. (manufacturer of
the Vu-Phone) and is assumed to be consistent with other brands as the
Vu-Phone is compatible with all other TDD's.
(1985)
--------------
Curtis E. Reid				CER2520@ritvax.isc.rit.edu
Rochester Institute of Technology/NTID	REID@DECUS.org (DECUS)
P.O. Box 9887				716.475.6089 TDD/TT 475.6895 Voice
Rochester, NY 14623-0887  U.S.A.	716.475.6500 Fax (Business Use Only)



From telecom@delta.eecs.nwu.edu Tue Mar 23 13:53:43 1993
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Date: Tue, 23 Mar 1993 12:53:35 -0600
From: TELECOM Moderator <telecom@delta.eecs.nwu.edu>
Message-Id: <199303231853.AA07817@delta.eecs.nwu.edu>
To: ptownson@gaak.LCS.MIT.EDU
Subject: tdd.specifications
Status: RO


 From: "Curtis E. Reid" <CER2520@ritvax.isc.rit.edu>
 Subject: Request to put in telecom-archives at lcs.mit.edu

PAT,

Can you put the TDD specifications in the TELECOM-ARCHIVES at lcs.mit.edu? 
Maybe call it tdd.specs ?  I get so many requests for the specifications that I
think it might be justified by keeping a separate file that you and I can tell
readers to pull this file out from the archives.  What do you say?  Thanks!

	--Curtis
-----CUT HERE---------
               Specifications For TDD Data Transmit/Receive
 
All TDD manufacturers follow these specs but no tolerance level is given:
 
1.  Acoustic coupling (standard G- and K- type handset)
 
    Input level: 65 dB SPL minimum / 110 db SPL maximum
                                   -4        2
                 (0 dB SPL = 2 x 10   dyne/cm )
 
    Output level: 95 dB SPL minimum / 100 dB SPL maximum
                  (acoustic pressure to produce a -9 dBm
                   signal at the telephone set line terminals
                   on an average loop)
 
2.  Direct modular connection
 
    Connector:  standard 6-position modular jack
 
    USOC No.:   RJ11C
 
    Input level: -50 dBm minimum / 0 dBm maximum
 
    Output level: -13 dBm minimum / -9 dBm maximum
 
3.  Modem
 
    Modulation method:  Frequency Shift Keying
 
    Mark frequency:  1400 Hz +-5 Hz
 
    Space frequency:  1800 Hz +-5 Hz
 
    Signal to noise ratio:  13 dB
 
    Carrier to data delay:  180 ms
 
    Carrier to hold time:  156 ms
 
4.  Protocol
 
    Code:  Baudot
 
    Mode:  Half duplex
 
    Transmissions:  Asynchronous
 
    Start bit:  1
 
    Stop bit:   1
 
    Data bits:  5
 
    Parity:  None
 
    Data rate:  45.5 baud (buffered)
 
Note: The above information is from Plantronics, Inc. (manufacturer of
the Vu-Phone) and is assumed to be consistent with other brands as the
Vu-Phone is compatible with all other TDD's.
(1985)
--------------
Curtis E. Reid				CER2520@ritvax.isc.rit.edu
Rochester Institute of Technology/NTID	REID@DECUS.org (DECUS)
P.O. Box 9887				716.475.6089 TDD/TT 475.6895 Voice
Rochester, NY 14623-0887  U.S.A.	716.475.6500 Fax (Business Use Only)