U.S. patent application number 10/412118 was filed with the patent office on 2004-01-22 for text enhanced telephony.
Invention is credited to Colwell, Kevin, Engelke, Robert M..
Application Number | 20040013242 10/412118 |
Document ID | / |
Family ID | 27568860 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040013242 |
Kind Code |
A1 |
Engelke, Robert M. ; et
al. |
January 22, 2004 |
Text enhanced telephony
Abstract
A system is described for assisting the hard of hearing in the
use of the telephone, the system termed here text enhanced
telephony or TET. The hard of hearing user uses a TET device or
appliance which permits the user to speak and to hear the words
spoken by the other party, the TET device also supplying to the
user a text character stream of the words spoken by the other
party. The TET system uses the system of voice-to-text relays,
already in existence to assist the deaf community communicate with
hearing persons over the telephone, to translate the spoken voice
into a text stream. The TET relay and TET device are capable of
separating voice and digital communications frequencies carrying
text so that voice and a text communications stream of the words
spoken by the voice can be carried over a common telephone line.
The devices can also be capable of automated capabilities such that
the devices can automatically configure a three-party relay call
without the need for the user's instructions.
Inventors: |
Engelke, Robert M.;
(Madison, WI) ; Colwell, Kevin; (Middleton,
WI) |
Correspondence
Address: |
Nicholas J. Seay
Quarles & Brady LLP
P O Box 2113
Madison
WI
53701-2113
US
|
Family ID: |
27568860 |
Appl. No.: |
10/412118 |
Filed: |
April 11, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10412118 |
Apr 11, 2003 |
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09977842 |
Oct 15, 2001 |
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6549611 |
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09977842 |
Oct 15, 2001 |
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09572819 |
May 17, 2000 |
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6307921 |
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09572819 |
May 17, 2000 |
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09034076 |
Mar 3, 1998 |
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6075842 |
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09034076 |
Mar 3, 1998 |
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07842943 |
Jan 9, 1992 |
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5351288 |
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07842943 |
Jan 9, 1992 |
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07616720 |
Nov 16, 1990 |
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5081673 |
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07616720 |
Nov 16, 1990 |
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07255357 |
Oct 11, 1988 |
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10412118 |
Apr 11, 2003 |
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08129894 |
Sep 30, 1993 |
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5432837 |
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10412118 |
Apr 11, 2003 |
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08155061 |
Nov 19, 1993 |
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5517548 |
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08155061 |
Nov 19, 1993 |
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07886552 |
May 20, 1992 |
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Current U.S.
Class: |
379/52 ;
379/93.17 |
Current CPC
Class: |
H04M 11/066 20130101;
H04M 3/42391 20130101 |
Class at
Publication: |
379/52 ;
379/93.17 |
International
Class: |
H04M 011/00 |
Goverment Interests
[0002] Not applicable.
Claims
We claim:
1. A text enhanced telephone station to receive both voice and text
communications simultaneously over the same telephone line, the
text communications transmitted using two digital communication
tones, the station comprising: a telephone hand set including a
speaker and a microphone; a connector adapted to be connected to
the telephone line; input wiring to carry input signals from the
connector to the speaker; output wiring to carry output signals
from the microphone to the connector; a notch filter is constructed
to preferentially obstruct the passage of the two digital
communication tones, the notch filter being connected in the input
wiring to filter signals to the speaker so that the digital
communications tones are not passed to the speaker; a modem
connected to the input wiring before the notch filter to convert
any text communication at the digital communication tones to
digital signals; a microcontroller connected to receive the digital
signals from the modem and to identify the characters encoded in
the digital form; and a visually readable display to display the
characters identified by the microcontroller, the microcontroller
programmed to display on the display the characters as they are
received so that text communications received by the station
representing the words spoken by a remote user can be displayed to
be read by a user.
2. A text enhanced telephone as claimed in claim 1 wherein the
digital communication tones are 1400 and 1800 hertz.
3. A text enhanced telephone as claimed in claim 1 wherein the
microprocessor is programmed, when asked to initiate a call by the
user, to (i) receive a telephone number from the user, (ii) dial
and connect to a text enhanced telephone relay instead of the
dialed telephone numbers, (iii) send to the relay machine control
functions in an enhanced TDD protocol which directs the relay to
dial the dialed telephone number and initiate text enhanced relay
communications between the user and the dialed number.
4. A text enhanced telephone as claimed in claim 3 wherein there is
further a plurality of user accessible switches to control the
function of the microprocessor to turn on and off the automatic
dialing of the text enhanced telephone relay.
5. A text enhanced telephone as claimed in claim 1 wherein there is
a second notch filter on the output wiring to filter from the voice
of the user any tones at the digital communication tones.
6. A text enhanced telephone as claimed in claim 1 wherein there is
a band pass filter connecting the modem to the input wiring to pass
only the digital communication tones to the modem.
7. A text enhanced telephone communication device adapted to being
connected in series between a conventional telephone and a
telephone line to permit both voice and text communications to be
carried on a common telephone line, the text communications carried
at digital communication frequencies, the device comprising: a
first connector to connect to the telephone; a second connector to
connect to the telephone line; two hybrids to separate onto
separate wires the telephone signals outbound from the telephone
from the telephone signals inbound to the telephone; a notch filter
connected in the wire for the inbound telephone signals connected
to filter out any digital communications frequencies to prevent
passage of text communications to the telephone; a decoding circuit
connected to the wire carrying the inbound telephone signals before
the notch filter to decode the text communications from the digital
communications frequencies; a visual display; and a microcontroller
connected to the output of the decoding circuit programmed to
decode the text characters in the text communications and to
promptly display the characters on the visual display as the
characters are received, wherein the device can receive both voice
and text communications on the same telephone line with the voice
passing to the user while the text communications of the spoken
words are used to create a visual text character stream for reading
by the user.
8. A text enhanced telephone as claimed in claim 7 wherein the
digital communication frequencies are 1400 and 1800 hertz.
9. A text enhanced telephone device as claimed in claim 7 wherein
the microcontroller is programmed, when asked to initiate a call by
the user, to (i) receive a telephone number from the user, (ii)
dial and connect to a text enhanced telephone relay instead of the
dialed telephone numbers, (iii) send to the relay machine control
functions in an enhanced TDD protocol which direct the relay to
dial the dialed telephone number and initiate text enhanced relay
communications between the user and the dialed number.
10. A text enhanced telephone device as claimed in claim 9 wherein
there is a user accessible switch to control the function of the
microcontroller to turn on and off the automatic dialing of the
text enhanced telephone relay.
11. A text enhanced telephone device as claimed in claim 7 wherein
the device also includes a dual tone multifrequency receiver to
receive and decode dialing by the user.
12. A text enhanced telephone device as claimed in claim 7 wherein
there is a second notch filter connected in the wire for the
outbound telephone signal to filter out any voice components at the
digital communications frequencies.
13. A text enhanced telephone device as claimed in claim 7 wherein
there is a band pass filter connecting the decoding circuit to the
wire carrying the inbound telephone signals to pass only signals at
the digital communications frequency to the decoding circuit.
14. A text enhanced telephone communication device adapted to being
connected in series between a conventional telephone handset and
the telephone base unit, and adapted to permit both voice and text
communications carried at digital communications frequencies to be
carried on a common telephone line connected to the telephone, the
device comprising: a first connector to connect to the telephone
handset; a second connector to connect to the telephone base unit,
the first and second connectors being connected by inbound and
outbound telephone wires; a notch filter connected in the inbound
wire to filter out any digital communications frequencies from
transmission to the telephone handset; a decoding circuit also
connected to the inbound wire to decode the text communications
from the digital communications frequencies; a visual display; a
microcontroller connected to the output of the decoding circuit and
the visual display and programmed to decode the text characters in
the text communications and to promptly display the text characters
on the visual display as the text characters are received, wherein
the device can receive both voice and simultaneous text
communications on the same telephone line with the voice passing to
the user while the text communications are used to create a
simultaneous visual text character stream for the user of the words
being spoken by the voice.
15. A text enhanced telephone device as claimed in claim 14 wherein
the digital communication frequencies are 1400 and 1800 hertz.
16. A text enhanced telephone device as claimed in claim 14 further
including a notch filter connected in the output wire to prevent
the user's voice from interfering with the text communications.
17. A text enhanced telephone device as claimed in claim 14 further
including a band pass filter connecting the decoding circuit to the
inbound wire so as to present only the digital communications
frequencies to the decoding circuit.
18. A text enhanced telephone station for communicating in both
voice and text characters over the same telephone line, the text
characters being transmitted at two discrete digital communication
frequencies, the station comprising a telephone handset including a
speaker and a microphone; a notch filter connected to the speaker
to prevent the passage to the speaker of both of the digital
communication frequencies; a decoding circuit connected to the
telephone line and responsive to signals at the digital
communications frequencies received over the telephone line to
convert those signals to digital signals; an analog output circuit
connected to the telephone line to convert digital information into
signals at the two digital communications frequencies; a visually
readable display; and a microprocessor connected to the decoding
circuit and the analog output circuit and the display, the
microprocessor programmed to display text characters received in
digital form from the decoding circuit on the display so that the
user can hear a voice and also see the text of the words that are
spoken, the microprocessor also being programmed to, if a user
indicates that a text enhanced call is to be originated, to
transmit on the telephone line a series of command codes causing a
relay to be connected as well as the called party, so that the
relay can supply the text of the words spoken by the called party
for display to the user.
19. A text enhanced telephone station as claimed in claim 18
wherein there is also a notch filter connected to the microphone so
that the user's voice is filtered at the digital communications
frequencies to prevent interference with the text
communications.
20. A text enhanced telephone as claimed in claim 18 wherein the
microprocessor indicates that a text enhanced call is to be made by
communicating with the relay in an enhanced TDD communication
protocol that permits command functions to be transmitted to the
relay.
21. A text enhanced telephone as claimed in claim 20 wherein the
enhanced TDD communication operates at the digital communications
frequencies of 1400 and 1800 hertz.
22. A relay for use in a telephone system for text enhanced
communication and operated by a call assistant, the relay
comprising a first telephone line connected to a hearing user; a
second telephone line connected to a text enhanced user; an audio
telephone linkup with a speaker connected to the first telephone
line so that the call assistant can hear words spoken on the first
telephone line; a communications terminal connected for
transmitting a text character stream using digital communication
frequencies to the second telephone line; a notch filter connecting
the second telephone line, the notch filters filtering out the
digital communication frequencies such that voice can pass between
the first and second telephone lines while no digital communication
frequencies are passed to the first telephone or to the call
assistant, thus permitting the call assistant to pass to the text
enhanced user a text character stream of the words spoken by the
hearing user without either of the hearing user or the call
assistant hearing the digital communication frequencies.
23. A relay as claimed in claim 22 wherein the notch filter filters
out the digital communications frequencies of 1400 and 1800
hertz.
24. A relay as claimed in claim 22 wherein there is also notch
filter connected to the second telephone line so that any
components of the voice of the hearing user do not interfere with
the text communications between the call assistant and the text
enhanced user.
25. A relay as claimed in claim 22 wherein both of the notch
filters filter out the digital communication frequencies of 1400
and 1800 hertz.
26. A relay as claimed in claim 22 wherein the digital
communications terminal is capable of receiving command codes from
a text enhanced telephone device operated by the text enhanced user
to cause the terminal to dial another party and automatically
commence text enhanced telephone communications between the text
enhanced user and the other party.
27. A relay for use in a telephone system for text enhanced
communication and operated by two call assistants, the relay
comprising a first telephone line connected to a first text
enhanced user; a second telephone line connected to a second text
enhanced user; an audio telephone linkup with a speaker connected
to each of the first and second telephone lines so that a
respective call assistant can hear words spoken on each of the
respective telephone lines; a communications terminal for each call
assistant connected for transmitting a text character stream using
digital communication frequencies, the terminal for each call
assistant connected to transmit on the other telephone line than
the one on which the call assistant is hearing words spoken; a pair
of notch filters connecting the telephone lines, the notch filters
filtering out the digital communication frequencies such that voice
can pass between the telephone lines while no digital communication
frequencies are passed to the users or to the call assistant, thus
permitting the respective call assistants to pass to a one of the
two text enhanced user a text character stream of the words spoken
by the other text enhanced user without either of the text enhanced
users or the call assistants hearing the digital communication
frequencies.
28. A method for text enhancing telephone communications between a
first telephone user who is hard of hearing or is deaf but can
speak understandably and a second telephone user who can speak and
hear the spoken word, the method comprising the steps of connecting
between the first and the second users a relay including speech to
digital communications conversion capability such that the digital
conversion of the text of the spoken words of the second user are
transmitted at digital communications frequencies on the telephone
line to the first user at the same time as the voice of the second
user is transmitted over that same telephone line, at the telephone
station of the first user, filtering the incoming signal to the
speaker of the first user so that the frequencies of digital
communications are eliminated from the signal to the speaker; and
at the telephone station of the first user, simultaneously
translating the digital conversion of the text received to text and
displaying the text in visually readable form so that the first
user receives both the voice of the second user as well as a text
transcription of the words spoken by the second user.
29. A method as claimed in claim 28 wherein the digital
communications conversion capability includes a human call
assistant connected telephonically to the second user who enters
words spoken by the second user into a digital communications
terminal which places the text conversion in digital form at
digital communications frequencies on the telephone line to the
first user.
30. A method as claimed in claim 28 further comprising the step of
at the telephone of the first user and at the relay filtering the
telephone lines carrying voice to remove from the voices any
frequency components at the digital communications frequencies so
that the voice signals do not interfere with the text
communications.
31. A method as claimed in claim 30 wherein the digital
communications frequencies are 1400 and 1800 hertz.
32. A method as claimed in claim 28 further comprising the step of
the first user initiating the call by dialing a number into a
telephone connected to a text enhanced telephone device the text
enhanced telephone device intercepting the dialed number and
dialing instead the relay, the text enhanced telephone device then
transmitting command codes to the relay instructing the relay to
dial the number dialed by the first user and to initiate text
enhanced communications through the relay with the dialed number.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of Ser. No.
07/842,943 filed Jan. 9, 1992, which was a continuation-in-part of
Ser. No. 07/616,720 filed Nov. 16, 1990, now U.S. Pat. No.
5,081,673, which was a continuation of Ser. No. 07/255,357 filed
Oct. 11, 1988. This application is also a continuation-in-part of
Ser. No. 08/129,894 filed Sep. 30, 1993 and of Ser. No. 08/155,061
filed Nov. 19, 1993, both of which are continuations-in-part of
Ser. No. 07/886,552 filed May 20, 1992.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to telephone communication in
general and relates in particular, to assisted telephone
communication for persons having attenuated hearing capability.
[0004] Much of modern personal communication, both in social and
business environments, takes place through the telephone. Yet,
there are many persons in society who have attenuated hearing
capability and are thus disabled or incapable or handicapped in
using the voice telephone system commonly in use today. For person
who are deaf, there has for some time been a system of
communication through the telephone system which has been used by
the deaf community. That system makes use of devices known as
telecommunication devices for the deaf (TDDs), also known as text
telephones (TTYs). Current TDDs are electronic devices consisting
of a keyboard and a display and a modem, to acoustically or
directly couple to a telephone line, which permit the user to type
characters into their keyboard, with the characters then be encoded
and transmitted over the telephone line to be displayed on the
display of a communicating or remote TDD.
[0005] Current TDD communication is conducted in a code, known as
Baudot or Baudot/Weitbrecht, which evolved historically at a time
when many telecommunication devices for the deaf were based on
mechanical or electromechanical devices rather than the current
generation of electronic devices. Accordingly, the Baudot protocol
was constructed for a set of constraints which are no longer
relevant to present day devices. The original Baudot protocol was a
uni-directional, or simplex, system of communication conducted at
45.5 baud. The normal Baudot character set consists of a 5 bit
characters, and the system is a bi-tonal system based on 1400 and
1800 hertz tones. The protocol does not utilize a carrier when no
signals are being sent, and because of the protocol for character
transmission, which includes a start bit and at least 1 1/2 stop
bits, it is only possible to send approximately 6 characters per
second, one way, during conventional Baudot communications.
[0006] In spite of its limitations, the Baudot communication
system, and TDDs, are widely used within the community of persons
who are deaf. In addition, systems have been implemented to permit
users of the TDD system to communication with hearing people. This
is done through the use of a so-called "relay." A relay, as used
herein, refers to a system of voice to TDD communication which uses
an operator referred to as a call assistant who serves as an
intermediate between a hearing user on one telephone line and a
deaf TDD user on a second telephone line. The call assistant wears
a headset to communicate by voice with the hearing user and also
has access to a TDD so that the call assistant can communicate with
the deaf user via the TDD. Thus, the call assistant serves as an
intermediary between the deaf person and the hearing person so as
to, in effect, translate from voice to digital electronic forms of
communication.
[0007] While the TDD communication system has a constituency within
the deaf community, it is not widely used by persons who are
deficient in hearing capability, but would not describe themselves
as deaf. Many otherwise fully able persons, particularly elderly
ones, suffer attenuated hearing capability due to aging, disease,
or other traumatic condition. Many persons who have some degree of
hearing capability left do not consider themselves "deaf," and
therefore will tend not to avail themselves of specialized
equipment intended for the deaf community. If a person has spent
much of his or her life engaged in oral communication using the
spoken word in the telephone, it is difficult to accept that
telephonic communication may become difficult or impractical as
one's hearing declines in efficiency. No system has heretofore
existed which is capable of assisting the person who has
significant hearing loss, in communication over the telephone in a
manner which emulates, to the fullest extent possible, the normal
telephonic communication patterns of hearing people.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention is summarized in that a text enhanced
telephonic device is made available to persons who have a hearing
loss. The text enhanced telephone will, to the user, operate like a
normal telephone but will, in addition to receiving normal voice
communication, permit the user to receive the words spoken by the
remote party in a visual format on a visual display located on the
text enhanced telephone which the user is operating.
[0009] It is an object of the present invention to provide a text
enhanced telephone which may be operated by a user who is hearing
deficient in a manner like all conventional telephones, but with
the added capability that received communications are displayed in
text so that the user can read the communications to supplement any
words which are not understood verbally.
[0010] It is a feature of the present invention that the operation
of the text enhanced telephone can be made transparent to the user
so that little or no retraining or otherwise adaptive behavior
needs to be taught to the user of the system.
[0011] Other objects, advantages, and features of the present
invention will become apparent from the following specification
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] FIG. 1 is a schematic circuit diagram of one embodiment of a
text enhanced telephone (TET) constructed in accordance with the
present invention.
[0013] FIG. 2 is a schematic illustration of the operation of a
conventional TDD relay.
[0014] FIG. 3 is a schematic illustration of the operation of a TDD
relay with voice carry-over.
[0015] FIG. 4 is a schematic illustration of the operation of a
text enhanced telephone (TET) relay system.
[0016] FIG. 5 is a circuit diagram of a TET relay for use in the
system of FIG. 4.
[0017] FIG. 6 is a timing diagram of synchronization sequences for
use in an enhanced TDD protocol useful in the present
invention.
[0018] FIG. 7 is a circuit diagram of a notch filter useful in a
TET device.
[0019] FIG. 8 is a circuit diagram of another embodiment of a notch
filter which can be used in a TET device.
[0020] FIG. 9 is a circuit diagram of another embodiment of a TET
device.
[0021] FIG. 10 is an exterior view of another embodiment of a TET
device.
[0022] FIG. 1 is a circuit diagram of an alternative relay
circuit.
[0023] FIG. 12 is a circuit diagram of another alternative relay
system.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The present invention envisions a new class of telephone
communications equipment, here termed text enhanced telephones or
TETs. These TET devices are intended to assist the hard of hearing
person in the use of a telephone to communicate with others in a
normal fashion. The text enhanced telephone device can be packaged
in any of several ways. The device can be, for example, any of (i)
an intermediate appliance plugged in between the handset and the
telephone base, (ii) an intermediate appliance plugged in between
the telephone and the wall jack or (iii) a unitary device built
into the telephone itself. Whichever physical form it takes, the
TET device includes a visual display onto which text characters may
be displayed. The user of the TET uses the device as they would a
normal telephone. The difference is that for a TET, in addition to
the remote persons' spoken voice being heard over the telephone
speaker or earpiece, the words spoken by the remote user appear in
written text form on the visual display, where they can be read by
the person with hearing difficulty. Thus, to the person who is
hearing impaired, the use of the TET device is "normal," and in
accord with their usual habit, and the person gains the benefit of
any non-verbal spoken cues, such as inflection, volume, pauses, or
the like, that the user can hear, as well as receiving in a text
character stream all of the words actually spoken by the other
person.
[0025] The functioning of such a device will preferably be based on
an enhanced TDD protocol, such as the one which will be disclosed
below. It is to be understood, however, that TET can also be
implemented in devices operating in conventional Baudot or other
digital text data protocol, such as ASCII or CCITT. A TET device
may also employ the existing relay system to serve as the
communication link to convert oral to text communication, also as
will be described below. Thus the specification below will begin
with a schematic of the prototypical TET device, followed by a
description of the preferred code system, a description of relay
operation in general, and then a description of several of the
variants of TET design which may be utilized within the system of
the present invention.
The Text Enhanced Telephone
[0026] Shown in the schematic illustration of FIG. 1 is the
circuitry of one embodiment of a version of a text enhanced
telephone (TET) operated in accordance with the present invention.
The TET device of FIG. 1 is a device intended to be inserted in
series in between the base unit of a conventional telephone and the
wall jack into which the telephone is connected. Therefore, at its
input, and its output, the TET of FIG. 1 is configured to have
conventional analog telephone connectors or jacks. Indicated at 12
is the jack which would be connected to the telephone, and
indicated at 14 is the jack which would be connected to the
telephone wall jack. Connected to each of the respective input and
output jacks 12 and 14 is a device referred to in the telephone
industry as a hybrid or a two-wire to four-wire converter, the two
hybrids being labeled 16 and 18 respectively. These hybrids,
conventional in the telephone and data communications industry,
serve to either separate or combine the transmitted and received
analog telephone signals or, as their other name implies, separate
the two-wire telephone signal into four wires. On the transmit
line, which is created from the hybrid 16, the line is connected
next to a notch filter 20. The notch filter 20, of conventional
design in the art, is specifically intended to pass signals of all
frequencies, except those at the digital text communication
frequencies, which are 1400 and 1800 hertz for the enhanced TDD
protocol described below. The output of the notch filter 20 is
connected through an analog summer 24 to the input side of the
hybrid 18. The output side of the hybrid 18 is connected as an
input to a notch filter 22, which is similar in design to the notch
filter 20, and also constructed to provide filtering of signals at
1400 and 1800 hertz. The output of the notch filter 22 goes as the
input to the hybrid 16.
[0027] Also connected to the same line that goes to the input of
the notch filter 22 is a band pass filter 26. The band pass filter
26, also of a design conventional within the art, is the converse
of the notch filters 20 and 22. The band pass filter 26 is intended
to pass only signals at 1400 and 1800 hertz. The output of the band
pass filter 26 is connected to a tone detect circuitry 28, or
receive modem as they are also termed, of a type conventionally
used in TDD devices. The tone detect circuitry 28 detects either
1400 or 1800 hertz, and provides an appropriate digital output to a
microcontroller 30. The microcontroller 30 includes a
microprocessor and appropriate ROM and RAM memory. Code stored in
the ROM directs the operation of the microprocessor. On the output
side of the microcontroller 30 is a digital to analog converter 32,
the output of which is connected as the other input to the analog
summer 24. A DTMF decode circuit, indicated at 34, is connected to
the output line from the hybrid 16, and is the type of device
intended to decode the dual tone multifrequency, or "Touch Tone,"
(Trademark) signals from a push button telephone. The output of the
DTMF decode circuit 34 is also connected as an input to the
microcontroller 30. The microcontroller 30 also operates a normally
closed switch, or relay, 35 located between the hybrid 16 and the
notch filter 20 after the connection to the DTMF receiver 34. A
series of user accessible switches 36 are also connected as inputs
to the microcontroller 30. The microcontroller 30 is also connected
to a visual display 38 which is capable of providing an
alpha-numeric display of text characters presented to it by the
microcontroller 30. Separately, a bypass circuit, designated at 40,
and controlled by an on/off switch 41, is connected between the
input and output telephone jacks 12 and 14 directly and which, when
actuated, is capable of bypassing the entire internal components of
the device of FIG. 1.
[0028] The operation of the device will be described briefly here,
and then in more detail below. The purpose of the TET device, when
enabled, is to intercept the outgoing call placed by the user, as
detected by the DTMF decode circuit. The microcontroller 30, during
the dial by the user, intercepts the dialed tones and does not
present them on the output line by opening the switch 35. When the
user has finished dialing the number, the microcontroller 30
utilizes its analog capabilities, accessed through the D to A
converter 32, to present on the output line the DTMF signal for a
telephone number, but not the telephone number dialed by the user.
Instead, the microcontroller 30 dials the number of the TET relay
which the user normally utilizes. As the TET device makes initial
contact with the relay, the TET device passes to the relay a series
of machine command codes. The operation of such command codes will
be described below. The function of the command codes at this point
is to inform the relay as to the type of call to be implemented,
and then to pass to the relay the number for the ultimate hearing
person to be connected. The relay equipment will then automatically
dial the number of the hearing user and configure a TET relay with
a call assistant in the loop between the TET device, operated by
the TET user, and the hearing user at the other end of the
line.
[0029] When the set-up is completed, the hearing user speaks and
the call assistant types the words spoken by the hearing user into
the TDD at the relay. The telephone line between the TET and the
relay will carry both the spoken words of the hearing user and the
digital signals for the text typed into the device used by the
relay call assistant. In the TET device of FIG. 1, the purpose of
the notch filter 22 is to keep the text communication tones from
being heard by the TET user. At the same time, the purpose of the
notch filter 20 is to prevent the words spoken by the TET user from
inadvertently interfering with the transmission and receipt of the
digital communication tones. While the communication session is
on-going, the TDD tones are passed through the band pass filter 26
and detected and decoded by the microcontroller 30. The
microcontroller 30 decodes the digital text, and then presents a
text character stream of the words spoken by the remote party on
the visual display 38 so it can be read by the user. Thus the user,
without having to take specific action, has created a call in which
he or she may speak normally to the person at the other end of the
line, and the person at the other end of the line may also speak
normally. The hard of hearing or deaf user does not hear any of the
digital communication tones for the text, but sees at his or her
TET device a visual text character stream of the words spoken by
the user at the other end of the line, in a real time fashion.
[0030] These advantages to the user, and the intimate functioning
of the device of FIG. 1, can best be understood by understanding
some additional technical details of the device which will be
described below.
TET Relay
[0031] As relays for the TDD community are presently constituted,
the relay serves as a translator between Baudot or TDD users and
users who can speak and hear. The person employed at the relay,
referred to as a call assistant, sits at a TDD terminal and wears a
headset connected as a regular voice telephone. Using the TDD
operated by the call assistant, the call assistant communicates in
a digital code over one telephone line to the TDD user, preferably
using an enhanced TDD protocol. Using the headset, the call
assistant communicates over the second telephone line in normal
voice with the speaking and hearing party. In this way, the deaf
person is facilitated in communicating with hearing persons over
the telephone. Such relays are now maintained by local or regional
telephone exchanges all over the United States, and in other
countries, and are specifically intended to allow access to the
telephone communication system for users who have difficulty
hearing or who cannot hear.
[0032] One enhancement that has already been built into some relays
is intended to provide better telephone access to users who can
speak but not hear. Such persons may still use a relay, but use it
in a mode known as "voice bridge" or "voice carry-over" (VCO),
where the voice of the deaf or hard of hearing user is transmitted
through the relay to the hearing user. Such a voice bridge relay
system is discussed and disclosed in more detail in U.S. Pat. No.
5,081,673, the disclosure of which is hereby incorporated by
reference. Shown in FIGS. 2, 3 and 4 are schematically the
different arrangements of relay usage for normal relay, voice
bridge relay, and text enhanced telephony relay respectively. In
each of FIGS. 2, 3, and 4, the hearing and speaking user is at the
telephone 42.
[0033] The telephone 42 of the hearing and speaking user is
connected in FIG. 2 to the handset (or headset) 43 of the call
assistant who uses a TDD 44 to communicate with the TDD 46 of the
deaf or hard of hearing person.
[0034] In FIG. 3, the voice bridge, a switching circuit 48 connects
the telephone line from the telephone 42 to a telephone 50 accessed
by the deaf or hard of hearing user. The switching-circuit 48, such
as that described in the above U.S. Pat. No. 5,081,673, connects
the two telephones 42 and 50 such that when voice is on the line
and opens the circuit when TDD signals are on the line, as when
either of the TDDs 44 or 46 are operated. Thus, the variant of FIG.
3 permits text or voice on the same line, between the relay and the
disabled user, alternately, but does not permit simultaneous
transmission of text and voice. Also, since the telephone line
between the relay and the telephone 50 is switched to text
transmissions when the user at telephone 42 is speaking, voice is
never received at the telephone 50.
[0035] Illustrated in FIG. 4 is the general scheme for the typical
relay implementing TET. The telephone 42 of the hearing user is
connected by a first telephone line 45 to the handset 43 of the
call assistant. The call assistant types at the TDD 44, placing
data communications on a second telephone line between the relay
and the hard of hearing user who is at the telephone 50. A TET
appliance 52 is also placed in series with the telephone 50. A
filter circuit 51 connects the telephone line 45 from the hearing
user's telephone 43 to the telephone line 47. The filter circuit 51
is constructed such that all voice communications, but no data
signals from text, pass through the filter circuit 51, so that the
hearing user does not hear the communication tones of the text
transmissions. At the station of the deaf or hard of hearing user,
the TET appliance 52 receives the text communications from the TDD
44 and displays the received text characters for the user. At the
same time, the TET device 52 filters from the telephone line 47 the
text communications signals so that the user on telephone 50 only
hears the voice communications. Thus the users of the two
telephones 42 and 50 converse normally, with the communication to
the user of the telephone 50 assisted by the display of the text of
what is said by the other user onto the visual display of the TET
appliance 52.
[0036] Thus, to implement the present invention, some modifications
must be made to the configuration of the relay. A schematic diagram
showing such a modified relay for TET operation is shown in FIG. 5.
In FIG. 5 reference numerals are similar to FIG. 4 for similar
parts, such as the call assistant's headset 43, the TDD 44 of the
call assistant and the filter circuit 51, shown here in more
detail. At each of its ends, the relay of FIG. 5 includes hybrids
54 and 56 to separate the single telephone line carrying
communications in each direction into separate lines for each
direction. A notch filter 58 is connected to the hearing user's
telephone line 45. The notch filter 58 is, again, constructed so as
to pass through signals of all frequencies, except for signals at
the text communications frequencies, preferably the 1400 and 1800
hertz tones of enhanced TDD protocol. Also connected to the input
line is a amplifier 63, connected to supply voice from the hearing
user to the headset 43 of the call assistant. A side-tone amplifier
62 is connected to feed attenuated voice of the call assistant back
to the call assistant for normal voice feedback purposes. The
output of the notch filter 58 passes through AGC amplifier 64 and
an analog summer 66 to be connected to the telephone line 47 to the
TET user.
[0037] The telephone line 47 from the TET user, connected through
the hybrid 56, is passed through a notch filter 68, then through an
AGC amplifier 70 to the telephone line 45 to the hearing user. Also
optionally connected to the telephone line 47 from the TET user is
a band pass filter 72, constructed so as to pass only the digital
communication frequencies. The output of the band pass filter goes
to the TDD 44, while the output of the TDD 44 is connected through
the analog summer 66 to the TET user's telephone line 47.
[0038] The circuit of FIG. 5 thus permits both voice and text to be
carried simultaneously on the telephone line 47 between the TET
relay and the TET user. The text communication frequencies are
filtered out by the notch filter 68, so that the hearing user and
the call assistant will not hear the text communication tones.
Meanwhile, voice signals pass through the relay in both
directions.
[0039] The purpose of the notch filter 58 in the circuit of FIG. 5
is to minimize voice interference with accurate text
communications. Since normal human voice may contain frequency
components at 1400 and 1800 hertz, the voice signal could garble
the text communications between the call assistant and the TET
user. By using a narrow notch filter, little or no voice content is
perceived to be lost while the accuracy of text transmission is
maintained. If some garbling of text is acceptable, it may be
possible in some applications to omit the notch filter 58.
Similarly, the band pass filter 72, inserted to assure the
integrity of text communications, if desired, to the call
assistant, can be omitted if no such transmissions are to be
conducted.
[0040] Certain optional functions of the TET device, when used in
conjunction with the TET relay, are made possible by the use of the
enhanced TDD protocol and machine control codes. Thus these
protocols will be described next.
Enhanced TDD Protocol
[0041] To make use of the present invention, a code system is
required which permits the transmission of text communications
efficiently and quickly. The preferred system for use in the
present invention is an enhanced TDD protocol, specifically
designed to be backwardly compatible with the installed base of
Baudot TDD communication terminals. The enhanced TDD protocol is
based on frequency shift keying encoding an average, though
variable, transmission rate of just over 100 BAUD. The signals for
a logical 1 and logical 0 in the enhanced TDD protocol are just as
they are in standard Baudot, i.e. 1400 hertz for a mark and 1800
hertz for a space. However, the enhanced TDD protocol is unusual in
that, for reasons having to do with the electronics associated with
TDD tone recognition circuitry, the time for a space bit and the
time for a mark bit are defined to be different. The space bit is
defined to be 12 milliseconds, while the mark bit is defined to be
7 milliseconds. Moreover, the enhanced TDD protocol character set
consists of a 7 bit 128 character table, such as the ASCII or CCITT
character table, rather than the conventional 32 or 64 character
table used by conventional Baudot communications. This permits the
enhanced TDD protocol to use upper and lower case letters, as well
as leaving extra characters available for machine control
functions. The enhanced TDD character data signal consists of a
start bit, the 7 character bits, no parity bit, and 2 stop bits.
The start bit is a space and the stop bits are both marks.
[0042] The enhanced TDD protocol, like conventional Baudot
protocol, operates in a simplex mode, in which only one of the two
terminals communicating can be transmitting at any one time.
However, the details of operation of the enhanced TDD protocol
result in a pseudo-duplex capability. The pseudo-duplex capability
arises because each of the enhanced TDD protocol terminals is
constrained by virtue of its programming to operate in accordance
with two rules. The first rule is that each terminal is constrained
not to make any transmissions outward on its communication line
while it is receiving data. During the time period that the
terminal is receiving data, characters entered from the keyboard
are not transmitted, but are stored in a buffer. The enhanced TDD
protocol terminal will wait until there is a pause in the
communication line before transmitting characters from its buffer
in turn toward the other station. The second rule of pseudo-duplex
communication requires that the enhanced TDD terminal pause after a
certain N number of characters have been transmitted. The number of
characters N is between 1 and 72, and preferably between 1 and 20.
Thus, only one station is transmitting at a time, and the other
station listens and buffers characters until the first station
pauses, at which time it begins transmission of characters. The
effect of the operation of these two rules, together with the
higher speed of transmission achieved by communication at over 100
Baud, causes the communication between the two stations to appear
duplex to the users, even though on an electrical signal level,
communication is simplex. It is for this reason that this style of
communication is referred to as pseudo-duplex.
[0043] In addition to the other differences from conventional
Baudot communication, the enhanced TDD protocol requires a
recognition or handshake protocol in which the two stations must
establish that they are both capable of enhanced TDD protocol
communication before switching from conventional Baudot
communications to the enhanced TDD protocol. Accordingly, the
enhanced TDD protocol preferably includes a series of
synch-originate characters and synch-answer characters, which are
defined not to be printing characters, which the stations may
transmit to each other to identify themselves to each other and to
switch into enhanced TDD protocol communication. The
synchronization characters also have non-standard bit times so they
can be distinguished from displayable characters. To originate
communications, an originating special synchronization character,
referred to as the "O-synch" sequence is transmitted by the calling
station. If the called enhanced TDD device receives and recognizes
the O-synch sequence, and is capable of enhanced TDD communication,
then it transmits an "A-synch," or answer synchronization sequence,
to the originating station. FIG. 6 illustrates an exemplary O-synch
sequence at 74 and an exemplary A-synch sequence at 76. After
recognizing the transmission and receipt of these signals both
machines can then communicate in the enhanced TDD protocol. If the
enhanced TDD terminal fails to receive proper synchronization
sequence from the remote unit, it assumes that the remote unit is
operating in conventional Baudot protocol, and continues all
communication using the conventional Baudot protocol.
Machine Control Commands
[0044] The enhanced TDD protocol described above makes use of the
larger 7 bit character set. Unlike the smaller 32 character Baudot
character set, the 7 bit ASCII and CCITT character sets of 128
characters include both upper and lower cases as well as a full set
of punctuation characters, and also includes the capability to
include control characters. This permits the enhanced TDD to
operate with control codes not presently available in conventional
Baudot communications. Such control codes may be used to facilitate
machine-to-machine communication along the same telephone lines
used for communication between the users of the TDD devices, but in
a manner invisible to the users of the TDD terminals.
[0045] Of particular interest, and with relevance to the present
invention, are machine-to-machine commands for controlling and
sending information to a TET relay station. In particular, the TET
device, utilizing machine control commands transparent to the user,
can configure the relay to a method of communication which is
suited to the type of call that the originating station wishes to
make, i.e. to set itself up for TET communications. The type of set
ups will be described below after the method of implementing
machine control commands is described first.
[0046] A preferred system for machine control commands begins
through the use of special synchronization sequence which is
similar to the O-synch and A-synch, as described above. The special
synchronization sequence, indicating a machine command is to
follow, is here termed the [REQ] (request) sequence. The purpose of
the REQ sequence is to indicate that machine command codes follow
but to avoid requiring the user to wait while a lengthy character
set is transmitted to initiate machine-to-machine communication. A
form of [REQ] signal is indicated at 78 in FIG. 6.
[0047] The protocol for machine-to-machine messages under the
enhanced TDD protocol follows the following format:
[0048] [REQ][CATEGORY][FUNCTION][ERQ]
[0049] In a command of the format described above, [REQ] is the
synchronization signal described above which is defined to be a
non-printing character which is detectable by both the originating
and receiving machines operating under the enhanced TDD protocol.
The characters should be selected so as to be non-printing and
non-recognizable on a conventional Baudot TDD device.
[0050] As illustrated in FIG. 6, the [REQ] sequence begins with an
echo suppression pulse "EST" for 35 milliseconds to unlock the
receiving phase locked loops. This is followed by three 18
milliseconds mark tones and two 24 milliseconds mark tones, each
separated by twelve milliseconds of echo suppression tones. The
pattern is terminated with a 35 millisecond echo suppression pulse.
The [REQ] sequence is distinguishable from the A-SYNCH sequence by
the length of the final two mark tones.
[0051] The [REQ] sequence is not an ASCII character, both because
it does not conform to the format of an ASCII character with start
and stop bits flanking a sequence of marks and spaces, and because
it is not one of the character codes obtainable with the ASCII word
length. It follows, generally, that the [REQ] sequence may not be
initiated by the TDD user by pressing the keys on the keyboard. For
this reason, the [REQ] sequence is particularly well suited for
applications, such as initiating the "downloading" of emergency
information by an emergency service, which should be reserved to
particular users, such as legitimate emergency services.
[0052] The [REQ] sequence is followed by a [CATEGORY] character
which is a 7 bit binary number limited to 16 numbers from
hexadecimal 10H (16) to 1FH (31). These are nonprinting characters
under the ASCII character set and thus provide a degree of error
correction without risk of printing on the TDD. If the character
following the [REQ] sequence is not within the 10H to 1FH range
then the machine-to-machine communication procedure is aborted
before it causes a response or changes operation of the TDD.
[0053] In the preferred embodiment, [CATEGORY] 10H is reserved for
general machine-to-machine communication between TDDs, whereas
[CATEGORY] 11H is used for automatic machine-to-machine
communication for emergency services. [CATEGORY] 12H is used for
machine-to-machine communication for TDD or TET relay
functions.
[0054] The next character of the machine-to-machine message format
is a [FUNCTION] character which may be any 7 bit number. The value
of the [FUNCTION] character is interpreted in light of the
[CATEGORY] character previously transmitted. If the [CATEGORY]
character is 11H (emergency services), then a [FUNCTION] of 01H
instructs the originating TDD to transmit caller information in a
block format as will be described below. The pseudo-duplex
capabilities of the enhanced TDD protocol eliminates the
possibility that this block of information will be inadvertently
interrupted and garbled by transmissions by either party. If the
[CATEGORY] value is 12H (relay services), [FUNCTIONS] 01H to 06H
may be obtained as provided in Table I.
1 TABLE I 01H Number to dial 02H Carrier of choice 03H Relay user
ID 05H VCO on 06H VCO off 07H TET on 07H TED off 09H Transmit relay
information block
[0055] "Number to dial" is the number of the other party of the
conversation, which in this manner may be received and dialed
automatically by the relay without operator intervention to
eliminate the possibility of error in dialing, to speed the dialing
process, and to enhance the privacy of the communication.
[0056] [FUNCTION] 03H, the relay user ID is a personal
identification number that may be requested of the originating
caller to check for authorization of a particular user to use the
relay whereas [FUNCTION] 04H and [FUNCTION] 05H: "VCO On" and "VCO
Off" control a TDD voice bridge as described above.
[0057] For TET relay use, two machine commands may be used. The
first might be a [FUNCTION] 01H, directing the relay to dial a
remote hearing user to initiate communications. The second might be
a [FUNCTION] 06H, telling the relay to set up for a TET
configuration, such as is shown in FIG. 5.
[0058] The final portion of the machine-to-machine message format
is an [ERQ] (end of request) character which is a standard ASCII
character 04H. The termination of the machine command by the [ERQ]
character is used to allow the TDD software to respond to
machine-to-machine requests at variable lengths. For example, the
response to a request for emergency service caller information
could be any length from zero (no data) to tens of characters. The
initiating TDD would collect the characters until an [ERQ]
character was received. The format for a response to a
machine-to-machine request is simply
[0059] [REQ] [RESPONSE] [ERQ]
[0060] where [RESPONSE] is the responding data.
[0061] Thus these command functions, and the use of the enhanced
TDD protocol enable both the TET device and the relay to
automatically properly set up a call for the user. The enhanced TDD
protocol devices are capable of understanding their respective
roles in the TET relay system and acting accordingly. Thus, for
example, the TDD 44 of the call assistant may receive command codes
from the TET appliance of the TET user instructing it to dial
another party and automatically engage the relay in a TET
configuration.
[0062] Other command characters could select other parameters of
TET relay function. One could be two-directional TET. Another might
select voice privacy or a male or female call assistant. Text
protocols, code selections and similar technical parameters can be
selected by these commands. Thus the user education and
participation are minimized.
Circuit Details and TET System Variations
[0063] Thus, it can be appreciated from the above discussion that
the text enhanced telephone system and devices of the present
invention differ from prior devices in that the same telephone line
is used to carry voice and, at the same time, a digital signal
representing a text communication containing the words in text that
are being spoken simultaneously by voice. At each end of the
telephone line which carries both the text and voice
communications, care must be taken to filter the digital
communication frequencies from the earpieces of the users and also
to filter from the voice signals of each of the users any signals
at those text communication frequencies which might otherwise
interfere with the text communications. Thus the use of notch
filters is important to the present invention. Shown in FIGS. 7 and
8 are two embodiments of exemplary high performance notch filters
which may be used within the present invention. Many other designs
are, of course, possible as well.
[0064] Referring first to FIG. 7, which shows a type of notch
filter known in text books as "Twin-T," the input signal 80 is
connected through a pair of resistors 82 and 84 to the input of an
integrated circuit voltage follower. The input signal 80 is
connected through a capacitor 88 to ground and the junction of the
resistors 82 and 84 is connected through the series of a capacitor
90 and resistor 94 to ground, with the junction of the capacitor 90
and the resistor 94 also connected to the inverting input of the
voltage follower 86. The output of the voltage follower 86 is
connected through resistors 96 and 98 to the input of a second
integrated circuit voltage follower designated 100. Capacitors 102,
104, 108 and resistor 106 are connected similarly as to the
corresponding components associated with the voltage follower 86.
The voltage follower may be any of a wide number of integrated
circuits designed for this purpose, such as a National
Semiconductor LM102. The voltage follower 86 and the voltage
follower 100 operate as notch filters, with the frequency of the
notch being determined by the appropriate selection of resistors
and capacitors associated with each of the integrated circuits. By
appropriate choice of resistor and capacitor combinations, it is
possible to use the circuit of FIG. 7 to selectively notch filter
exactly 1400 and 1800 hertz from a broad band communication
signal.
[0065] Similarly, shown in FIG. 8, an input signal 80 is connected
as one input to a universal dual filter building block integrated
circuit 110. The filter building block integrated circuit also
receives a clock pulse on input line 111. The frequency of the
clock pulse on line 111 determines the frequency at which the
integrated circuit 110 performs filtering operations. The output of
the integrated circuit 110 is connected through a buffering
amplifier 112 to the input of a second universal dual filter
building block integrated circuit designated 114 which also is
driven by an appropriate clock signal 116. The output of the
integrated circuit 114 is connected through a buffer 118 to the
output signal 120. If the input line 111 to the integrated circuit
110 is operated at 140,000 hertz and the clock signal 116 to the
integrated circuit 114 is operated at 180,000 hertz, the series
combination of these two integrated circuits will create a dual
notch filter filtering out from the input signal a notch of
frequencies centered on 1400 and 1800 hertz respectively. A
suitable integrated circuit for use as the building block
integrated circuits 110 and 114 is the Linear Technology LTC 106 or
other similar integrated circuit.
[0066] Among the other ways that text signals can be separated from
voice, one other merits particular mention. It is possible to
digitize the entire telephone signal incorporating both voice and
text signals. Then it is possible to manipulate that digital signal
using a digital signal processing (DSP) integrated circuit, of
which many are commercially available. Using the DSP, a digital
filtering of the tones representing the frequencies of the text
communication can be done mathematically with high precision. After
processing, the DSP output is again converted to analog form for
presentation to the user.
[0067] Another variant possible within the present invention,
although perhaps a less desirable one, would be to construct a TET
circuit, similar to FIG. 1, but without the hybrid circuits. Using
a single telephone line, which carries signals both directions,
notch filtering would still be necessary to prevent text
communications from reaching the ear of the user. This device might
also use switching of the telephone line in response to sensed
signal type (i.e. local voice versus received voice and text) to
prevent input text signals from reaching the user's ear.
[0068] In FIG. 1 above, it was specifically envisioned that the
text enhanced telephone communication appliance was inserted in
series in between the telephone base station unit and the wall jack
to which the telephone was to be connected. While it is important
to the present invention that the TET device be capable of
receiving both digital communications and voice communications over
the common telephone line, there are several physical
configurations in which a TET device can be configured so as to
operate with, or replace, the conventional telephone. For example,
shown in FIG. 9 is another embodiment. In the embodiment
illustrated in FIG. 9, the TET appliance is placed in series
between the handset of a conventional telephone and the base unit.
The TET of FIG. 9 will not function to intercept and dial on behalf
of the user, so dialing of the TET relay must be manually by the
user, but other than that difference, the device of FIG. 9
functions in a manner quite similar to the TET device of FIG. 1. In
fact, those components in the embodiment of FIG. 9 which are
identical in their connection and function to the corresponding
components in the embodiment of FIG. 1 have been given identical
reference numerals, and will not be described in additional detail
herein.
[0069] Referring in detail to FIG. 9, the telephone handset 121 is
connected through a conventional jack 122. Since the connection
between the telephone base unit and the handset is conventionally a
four-wire connection, no hybrid circuit is required. The connector
or jack at the other end of the device, designated 124, is intended
to connect to the telephone base unit 123.
[0070] The device of FIG. 9 is particularly intended to function as
a receive TET device and to automatically commence operation when
digital electronic communications are received over the incoming
telephone line. Accordingly, there is an automatic voltage detect
circuit created using the operational amplifier 126. This amplifier
is constructed so as to detect when a signal of any kind is
received over the incoming telephone line to the handset. The
output of the operational amplifier 126 is connected to a buffer
128 which serves to turn the power on and off to the
microcontroller 30. Connected in series between the notch filter
22, which is placed on the incoming signal line is a volume, and
control circuit 130 which allows the volume and the handset to be
adjusted according to the user's desires.
[0071] Again, the in line TET device of FIG. 9 operates in a
fashion exactly analogous to the operation of the TET device of
FIG. 1, except that it is placed in between the handset and the
base station rather than between the base station and the wall jack
of the telephone. This embodiment does not intercept the dialing on
behalf of the user, but if the user is willing to dial the relay
manually, the circuit of FIG. 9 will satisfactorily and adequately
perform text enhanced telephonic communications, prevent digital
communications from being heard by user, and display any digital
communication signals received so that they can be read by user in
exactly the same fashion as the circuit of FIG. 1.
[0072] It is also specifically envisioned herein that rather than
building a separate appliance which is placed between the handset
and the base unit or between the base unit and the telephone jack,
the circuitry for the TET device can actually be constructed inside
the telephone itself in a single unitary appliance. The external
appearance of such a device is shown in FIG. 10. This device
incorporates the circuitry of FIG. 1 within the housing in which
the telephone is manufactured. The only change necessary to the
telephone exterior would be the need to provide for a display, so
that the digital display 38 can be seen by the users, and the need
to provide some place for a few controlling buttons 36 and 40 to
turn on and turn off or otherwise select the function of the TET
function. However, note that this device also includes a keyboard,
connected to the microcontroller, so that it can also be used as a
conventional TDD (send as well as receive) by users who need that
function as well.
[0073] It is preferred, as described above, that the digital
communication frequencies of the present invention be the Baudot
tones which are used in the enhanced TDD protocol described above.
The main reason for desiring the use of these Baudot tones, is that
so the devices can be compatible with other TDD and Baudot
communicating terminals and relays. However, it is also envisioned
herein that rather than using Baudot tones, that the digital
communications in accordance with the TET devices of the present
invention could actually be conducted in other digital
communication protocols, notably the ASCII or CCITT tone protocols
conventionally used by digital computers. The only differences in
the embodiments described herein which would be required through
the use of ASCII or CCITT, rather than Baudot tones, is that the
notch filters would have to be constructed so as to filter at the
frequencies of the ASCII or CCITT carrier tones, rather than at the
1400 and 1800 hertz signals used by both Baudot and enhanced TDD
communication protocols.
[0074] It is specifically envisioned that on occasions it may be
desirable to connect two, or more, TET users through a TET relay
such that both users may obtain the benefits of text enhanced
telecommunications. Shown in FIGS. 11 and 12 are two set ups by
which that objective can be accomplished. In the system of FIG. 11,
in which parts similar to the relay of FIG. 5 have been provided
with similar reference numerals, the system is set up to utilize a
pair of call assistants, one dedicated to transcribe the voice of
each of the two TET users. One of the call assistants utilizes the
TDD 44A and the telephone 43A while the other utilizes the TDD 44B
and the telephone 43B. Between the hybrids 56 and 54, two
oppositely oriented, and identical, circuits are provided analogous
to the circuit on one side of the TET relay of FIG. 5. The received
telephone signal goes through an AGC amplifier 64 and then through
a notch filter 58 to separate out voice components which might
interfere with data. The voice is fed to the telephone 43A or 43B
for the respective call assistant and also to a summer 66 where it
is summed with the output of the respective TDD 44A or 44B. The
system is completely symmetrical. Thus, between each hybrid and the
respective user, the telephone line carries simultaneously the
voice of the other user and a text communication which represents
the simultaneous transcription of what is said by the user at the
other end of the telephone. The text communications between the two
users do not interfere with the voice communications between the
users since, on each side of the relay indicated in FIG. 11, the
text is only transmitted to the user who desires to see that text
and the text and voice are carefully filtered from each other.
Again, as far as each user is concerned, they utilize their normal
telephone mannerisms and habits. The difference is that as each
user talks, the other user sees shortly thereafter a visual
indication of the text of what the speaker has spoken on the visual
display on his TET appliance.
[0075] Shown in FIG. 12 is yet another embodiment illustrating how
a two way TET relay could be constructed utilizing a single
operator. In this instance, the output of both telephones is
connected through a summer 141 to the telephone 43 of the operator.
A switch 144 is used either to allow both parties to see the text
of either transmissions or, alternately, the switch 144 can be
constructed so as to be toggled by the operator so that each party
only receives the text version of the words spoken by the opposite
party.
[0076] It is specifically contemplated herein that technological
developments over time will enable the function of the call
assistant to be, at some point in the future, an automated
function. Once computer assisted voice recognition systems become
practical such that they do not require training with a particular
voice, the call assistant in any of the relay configurations
described above could be replaced by an automated computer. The
computer would be programmed simply to translate into text the
words spoken by the user and to pass the text to the TET user in a
fashion similar to that described above. The only difference is in
circuitry would be that the human being representing the call
assistant, and that person's telephone and TDD, would be replaced
by an automated voice recognition digital electronic system.
[0077] It is also envisioned that there may be uses for the TET
technology described herein for situations other than the hard of
hearing user. For example, such a TET relay system could be
utilized for translations where a party understands a foreign
language, but only partially. By arranging to have a TET relay
operator who was capable of providing a simultaneous translation, a
user could arrange to have telephonic communications with a remote
user who speaks a language the TET user poorly understands. In that
instance, the call assistant would simultaneously translate and
type and the TET user could see on his or her display his own
native language translation of the words being spoken by the remote
user. A TET relay and appliance system may also be desirable in
situations where it is desired to record telephonic conversations.
It is a simple matter to attach a printer to a TET appliance of the
types described above. With such a TET appliance, and utilizing a
TET relay as described above, transcriptions of telephone calls
could be readily captured and printed in hard copy or stored on a
magnetic or other storage medium. This might be particularly useful
for conference calls, for business meetings or the like where
transcriptions of spoken words are desired. The service could also
be used to create transcriptions or text by a single user.
[0078] It is to be envisioned that the present invention is not
limited to the embodiments described and illustrated herein, but
embraces all such modified forms thereof as come within the scope
of the following claims.
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