U.S. patent number 3,833,765 [Application Number 05/327,953] was granted by the patent office on 1974-09-03 for keyboard and message system.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the. Invention is credited to Joseph D. Brabel, Kenneth J. Bray, Edwin H. Hilborn.
United States Patent |
3,833,765 |
Hilborn , et al. |
September 3, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
KEYBOARD AND MESSAGE SYSTEM
Abstract
A keyboard entry digital data transmission and reception system
employing a one-handed keyboard is disclosed. The novel keyboard
arrangement and the logic circuitry associated therewith permits
single data characters to be rapidly entered by a plurality of
sequential key depressions which uniquely define each
character.
Inventors: |
Hilborn; Edwin H. (Framingham,
MA), Brabel; Joseph D. (Concord, MA), Bray; Kenneth
J. (Medway, MA) |
Assignee: |
The United States of America as
represented by the Secretary of the (Washington, DC)
|
Family
ID: |
23278822 |
Appl.
No.: |
05/327,953 |
Filed: |
January 30, 1973 |
Current U.S.
Class: |
178/79; 178/17C;
400/88; 341/34; 400/472 |
Current CPC
Class: |
G06F
3/0235 (20130101); H03M 11/16 (20130101) |
Current International
Class: |
H03M
11/14 (20060101); H03M 11/16 (20060101); G06F
3/023 (20060101); G08b 001/00 (); H04b 001/00 ();
H04l 015/02 () |
Field of
Search: |
;178/17C,79,80,81,17.5
;340/365,172.5 ;235/145R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Robinson; Thomas A.
Attorney, Agent or Firm: Farmer; Herbert E. Edelberg; Nathan
Deeley, Jr.; Harold P.
Claims
What is claimed is:
1. Keyboard entry communications apparatus comprising:
keyboard means, said keyboard means having character entry keys
fewer in number than the total number of characters comprising the
language in which information is to be communicated;
means connected to said keyboard means for encoding signals
produced by the operation of each key on said keyboard means;
a plurality of storage devices connected to said encoding means for
temporarily storing encoded signals commensurate with key
operations;
steering logic means connected to said keyboard means and
responsive to each key operation for generating and applying
enabling signals sequentially to said temporary storage devices
whereby successive key operations will result in an encoded signal
being accepted by a different one of said temporary storage
devices;
memory means connected to said temporary storage devices and
responsive to the enabling of the last storage device in sequence
for accepting and storing encoded information from all of said
temporary storage devices, said information from all of said
temporary storage devices being commensurate with a unique
character defined by a plurality of successive key operations;
transmitter means connected to said memory means for transmitting
messages stored in said memory means, said messages comprising a
plurality of characters each uniquely defined by a plurality of key
operations; and
means for selectively enabling said transmitter means.
2. The apparatus of claim 1 wherein said keyboard means includes a
space key and wherein said steering logic means is responsive to
operation of the space key for generating a signal for
simultaneously enabling all of said temporary storage devices
whereby an encoded signal commensurate with a space will be applied
to said memory means upon operation of the space key.
3. The apparatus of claim 2 further comprising:
display means for providing an intelligible presentation of
information entered by said keyboard means on a real time basis,
said display means being connected to said memory means and
responsive to the entry of encoded information therein for
providing an indication of such information.
4. The apparatus of claim 3 wherein said encoding means
comprises:
a binary encoder; and wherein said communications apparatus further
comprises:
means connected between said temporary storage means and said
memory means for converting the plural binary coded signals in said
temporary storage devices into a code compatible with said display
means.
5. The apparatus of claim 1 further comprising:
means for storing a programmed identification message;
selector means having input terminals connected to said programmed
identification message storing means and said memory means, said
selector means having an output terminal connected to said
transmitter means; and
means responsive to command signals provided by said transmitter
means enabling means for controlling said selector means whereby
said programmed identification message and keyboard entered message
are sequentially delivered to said transmitter means.
6. The apparatus of claim 3 further comprising:
means for storing a programmed identification message;
selector means having input terminals connected to said programmed
identification message storing means and said memory means, said
selector means having an output terminal connected to said
transmitter means; and
means responsive to command signals provided by said transmitter
means enabling means for controlling said selector means whereby
said programmed identification message and keyboard entered message
are sequentially delivered to said transmitter means.
7. The apparatus of claim 4 further comprising:
means for storing a programmed identification message;
selector means having input terminals connected to said programmed
identification message storing means and said memory means, said
selector means having an output terminal connected to said
transmitter means; and
means responsive to command signals provided by said transmitter
means enabling means for controlling said selector means whereby
said programmed identification message and keyboard entered message
are sequentially delivered to said transmitter means.
8. The apparatus of claim 1 wherein said keyboard means
comprises:
a one-hand operated key set including ten alpha-numeric information
associated keys; and
means for providing a separate electrical output connection
commensurate with each key.
9. The key set of claim 8 wherein characters are associated with
the keys in alphabetical and numerical order.
10. The apparatus of claim 2 wherein characters defined by certain
of said plural sequential key operations will be commensurate with
words to be followed by numerical information and wherein said
memory means comprises:
a read only memory, said read only memory identifying those words
which are to be followed by numerical information and generating a
control signal commensurate therewith;
means responsive to control signals provided by said read only
memory for providing a signal to said steering logic means which
results in all of said temporary storage devices being
simultaneously enabled in response to each succeeding key operation
until the space key is operated.
11. The apparatus of claim 10 wherein said keyboard means
comprises:
a one-hand operated key set; and
means for providing a separate electrical output connection
commensurate with each key on said key set.
12. The apparatus of claim 11 wherein said encoding means comprises
a binary encoder.
13. The apparatus of claim 12 wherein said memory means further
comprises:
means connected between said temporary storage devices and said
read only memory for converting plural binary coded signals in said
storage devices into a code compatible to presentation to a human
operator.
14. The apparatus of claim 13 further comprising:
display means for providing an intelligible presentation of
information entered by said keyboard means on a real time basis,
said display means being connected to said read only memory means
and responsive to the entry of encoded information therein for
providing an indication of such information.
15. The apparatus of claim 14 further comprising:
means for storing a programmed identification message;
selector means having input terminals connected to said programmed
identification message storing means and said memory means, said
selector means having an output terminal connected to said
transmitter means; and
means responsive to command signals provided by said transmitter
means enabling means for controlling said selector means whereby
said programmed identification message and keyboard entered message
are sequentially delivered to said transmitter means.
16. The apparatus of claim 1 wherein said encoding means
comprises:
a binary encoder.
17. The apparatus of claim 16 wherein said memory means
comprises:
means connected to the output terminals of said temporary storage
devices for converting plural binary coded signals from said
storage devices into a code compatible to presentation to a human
subject; and
means connected between said code converter and said transmitter
means for storing a complete message in the form of a plurality of
characters defined by plural key operations.
18. The apparatus of claim 17 further comprising:
voice synthesizer means adapted to receive messages delivered out
of said storing means via said transmitter means in response to
operation of said transmitter means enabling means.
19. The apparatus of claim 18 wherein said keyboard means
comprises:
a one-hand operated key set including ten alpha-numeric information
associated keys; and
means for providing a separate electrical output connection
commensurate with each key.
20. The apparatus of claim 19 wherein said keyboard means includes
a space key and wherein said steering logic means is responsive to
operation of the space key for generating a signal for
simultaneously enabling all of said temporary storage devices
whereby an encoded signal commensurate with a space will be applied
to said code converting means upon operation of the space key.
21. The apparatus of claim 20 further comprising:
display means for providing an intelligible presentation of
information entered by said keyboard means on a real time basis,
said display means being connected to said code converting means
and responsive to the entry of encoded information therein for
providing an indication of such information.
Description
ORIGIN OF THE INVENTION
The invention described herein was made by employees of the United
States Government and may be manufactured and used by or for the
Government for governmental purposes without the payment of any
royalties thereon or therefor.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the coding and subsequent digital
transmission and reception of data and to the presentation of the
thus transmitted and received data in readily usable form. More
specifically, this invention relates to a keyboard entry data
transmission and reception system employing a one-handed keyboard
wherein single characters or information bits are uniquely defined
by a plurality of sequential key depressions. Accordingly, the
general objects of the present invention are to provide novel and
improved methods and apparatus of such character.
2. Description of the Prior Art
The necessity of increasing the speed and accuracy of data
transmission is particularly evident in the field of air traffic
control. At the present time most information exchange between an
aircraft and ground controllers is accomplished by voice
transmission. The present overload on voice transmission links as
utilized for air traffic control is forcing the need for digital
message transmission so as to free air time and permit an increase
in the number of messages which can be transmitted per unit of
time.
In order for digital data link transmission techniques to be
acceptable or adaptable for widespread usage, some form of keyboard
entry of information is required. The most basic form of keyboard
data entry device, of course, comprises the existing standard
typewriter keyboard. The standard keyboard typewriter, however,
originated as a purely mechanical device. Because of the initial
crudity of the mechanical linkages available, the characters on the
keys of early typewriters were intentionally positioned in a
somewhat awkward arrangement so as to slow the typist to a speed
compatible with capabilities of the mechanical apparatus. The
original typewriter keyboard layout has persisted to the present
time, although substantial equipment improvements have been made,
for the very basic reason that a change to a different character
layout would require the retraining of millions of typists as well
as the rebuilding of all existing typewriters.
Returning to a consideration of the air traffic control problem,
with which the present invention is concerned but not limited,
space constraints within aircraft cockpits are severe and this
factor alone dictates that the means for generating information for
the input to a digital message transmission system must be in some
form other than a standard typewriter keyboard. As a further factor
dictating against the use of a standard typewriter keyboard,
obviously an aircraft crewman cannot be expected to have two hands
free for efficient operation of a normal QWERTY keyboard.
Special purpose key sets have been developed and are presently in
use. The well known Stenotype machine represents one example of one
such special purpose keyboard. Extremely high input rates are
possible with a Stenotype machine through the use of chord keying.
However, use of a Stenotype machine requires an extended period of
training and the output is in coded form rather than in normal
English text.
To briefly summarize the foregoing, operations within complex
man-machine systems are imposing increasing needs for keyboard
entry of information under conditions where two-handed keying is
not feasible in the face of requirements for the performance of
other concurrent tasks. The piloting of airliners, operation of
police vehicles equipped with digital communication links and the
checkout of complex military and space systems represent examples
of technological areas wherein, even in the absence of space
constraints, use of a standard typewriter keyboard would be
inefficient when keyed by only one hand. Accordingly, a need
clearly exists for a simple one-handed keyboard and associated
logic systems which may be used for communication purposes. Such
equipment, while having initial utility in an area such as air
traffic control to replace the present inefficient use of voice
transmission, may be applied to a general purpose one-handed
typewriter. A typewriter capable of being produced in a pocket-size
version would have wide application to students taking lecture
notes, or for other persons who must regularly make records, and a
similar input device coupled to a speech synthesizer would permit
deaf mutes to communicate with the public at large.
SUMMARY OF THE INVENTION
The present invention overcomes the above briefly discussed and
other deficiencies and disadvantages of the prior art by providing
a limited-key input device having the capability of easy insertion
of alphanumeric information. In accordance with the present
invention a keyboard data entry device, with keys having electrical
contacts which actuate digital logic circuitry, is employed. In the
use of a preferred embodiment of the invention, the depression of
one key provides an electrical signal which is later modified or
added onto by a signal resulting from the depression of a second
key; character or bit presentation resulting only after the
depression of the second key. The present invention thus comprises
a uniquely organized one-handed keyboard, with a limited number of
data entry input keys, and associated logic circuitry whereby
single characters are uniquely defined by sequential key
depressions.
In the disclosed embodiment of the invention, which is directed to
an air traffic control application, the keyboard is used to enter a
message which is presented on a printer or a volatile display in
real time for proofreading; the message comprising a number of two
stroke defined characters. The displayed message is simultaneously
stored in binary form so that, when proofreading is completed, the
message may be transmitted at high speed to a remote terminal where
it may, for example, be used to activate a speech synthesizer which
then pronounces the message at a normal speaking rate. The digital
logic circuitry associated with the one-hand keyboard permits the
generation and transmission of normal English text or of
mnemonically coded messages. When mnemonically coded messages are
transmitted, the logic circuitry recognizes that such a message
would normally be followed by digits, for example indicative of
altitude or heading, and thus the circuitry performs an automatic
shift to numerals until such time as the space key is depressed
whereupon the system resumes use of double entered alphabetic
characters.
BRIEF DESCRIPTION OF THE DRAWING
The present invention may be better understood and its numerous
objects and advantages will become apparent to those skilled in the
art by reference to the accompanying drawing wherein like reference
numerals refer to like elements in the several figures and in
which:
FIG. 1 depicts a representative keyboard layout in accordance with
the invention;
FIGS. 2A and 2B, when placed side by side, are an electrical
circuit block diagram of data entry, storage and transmission
circuitry in accordance with an embodiment of the invention
employed in air traffic control; and
FIG. 3 is an electrical circuit block diagram of a receiver which
would be employed with the transmission circuitry of FIGS. 2A and
2B.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Solely for purposes of explanation, the present invention will be
described in the environment of a data link between an aircraft and
a ground controller. As noted above, the invention has much broader
utility. With reference to FIG. 1, a basic keyboard layout in
accordance with the present invention is depicted. In considering
the design of such a limited key set; i.e., a key set having fewer
keys than the number of characters which may be printed or words
which may be pronounced; it is desirable to place characters on the
keys in an easily remembered sequence. Such character placement
permits use of a coding scheme which is already familiar to an
appreciable proportion of the population of potential users of the
apparatus. An additional design consideration is to arrange the key
layout in the interest of permitting the full use potential of one
hand. In the keyboard of FIG. 1, these design considerations have
been fulfilled by arranging the letters and numerals in
alphabetical and numerical order, by allocating letters to keys
such that the keying of the first two letters of the words in the
ICAO phonetic alphabet will uniquely define each letter of the
English alphabet and by using a keyboard layout which permits four
finger operation.
With the keyboard layout of FIG. 1, since the keys are conveniently
placed under the fingers of one hand, rapid keying is possible even
though two key strokes are required for each letter to be typed. In
the basic form depicted, the keyboard uses only 26 of the possible
100 combinations of two key strokes and there are accordingly 74
additional combinations which may be employed. By way of example,
in the English language there are approximately 45 two and
three-letter combinations which occur with high frequency and some
or all of these combinations can be specified with two-key
combinations not used for the phonetic alphabet. Thus, after an
operator has learned basic keying of the ICAO combinations, he may
be taught the second-order combinations in order to reduce the
number of key strokes required to generate a given number of
letters. A third level of complexity may, obviously, also be
introduced in the interest of utilizing other common combinations
of English characters in order to further reduce the number of key
strokes required to produce a given amount of text.
The immediately preceding brief discussion is aimed at the
generation of normal English text. For special purposes, such as
air traffic control, it becomes possible to use other combinations
to produce mnemonic coding of special purpose messages. In the
preferred embodiment, the combinations required to produce the
phonetic alphabet are retained, but the remaining capacity of the
keyboard may be filled in a variety of ways. Thus, again
considering the example of air traffic control, two-letter
mnemonically coded messages may be generated such as:
Char- Ground to Air Air to Ground acter Transmission Transmission
______________________________________ 02 WEather (provides auto-
request for WEather matic transmission of information weather
information) 05 squaWK identification not used may be followed by a
numeric code) 07 You May (permiss- not used ion granted) 10 Contact
Wide area not used control (ARTCC) 11 Contact Approach not used
control 12 Contact Departure not used control 13 Contact Ground not
used control 15 AcKnowledge (ment) AcKnowledge (ment) 19 Contact
Tower not used or this may be a request for the frequency if it is
not automatically supplied by ground 25 Dump Information Dump
Information (means for clearing the display, not a transmitted
message, or transfer to another controller) 26 Flight Level? not
used in two-character (request for altitude format information) 28
not used Emergency Request for priority in use of voice channel 34
not used may I Go Higher? (request for a higher altitude) 36 not
used may I Go Lower? (request for a lower altitude) 46 Hold Level
(maintain Holding present Level present altitude) (might be
followed by digits to indicate reaching a requested altitude) 49
Hold after Taxiing Holding after Taxiing 51 not used Initial
Contact with a new controller. (should automatically provide flight
no., aircraft type and other pertinent info.) 52 If Feasible If
Feasible 56 I Locate you I Locate the traffic (radar contact) you
have pointed out 62 LEave a hold or LEaving (rolling, taking
restriction off, departing, etc.) 67 Lost Message Lost Message
(request (request for re- for retransmission) transmission) 68 what
is your Lowest not used in two-character Speed possible? format 71
you are Now Cleared not used 76 Not Located (can't traffic Not
Located find you on radar) 79 not used in two- report of reaching
the character format OUter marker 80 Stay With me (remain not used
on this frequency) 83 Restriction Gone not used (listed) 90 Thank
You Thank You 92 not used in two- estimated Traffic Delay character
format requested 99 TUrbulence (possible TUrbulence report from
wake of previous aircraft)
______________________________________
With respect to the use of "AK" for acknowledgement, as set forth
in the above tabulation, it is to be noted that present voice
transmission techniques require that any commands or advisories
from the ground be repeated by the pilot to assure the accuracy of
reception. For use of the present invention, the symbol "AK" can be
employed to cause automatic retransmission and automatic parity
check against the original transmission. This, in turn, will permit
the ground controller to turn his attention to a second aircraft
even before receipt of acknowledgment from the first.
It is also to be noted that a number of the standard messages
require subsequent transmission of digits. This may be accomplished
through the use of an automatic shift when decoding logic in the
transmission circuitry recognizes the particular combinations. The
messages which require subsequent transmission of digits
include:
Char- Ground to Air Air to Ground acter Transmission Transmission
______________________________________ 17 AltiMeter setting is not
used XXXX 26 not used in this format Flight Level is XXX 39 Go To
(altitude XXX) Going To (altitude) XXX 41 Hold at Altitude XXX
Holding Altitude XXX 44 Hold Heading XXX holding Heading XXX 48
Hold Speed at XXX Holding Speed at XXX 58 Increase Speed to XXX
Increasing Speed to XXX 68 not used in this format Lowest Speed
possible is XXX 69 Locate Traffic at XXX not used in this format 79
OUter marker is XXX not used in this format 82 Slow Down to XXX
knots Slowing Down to XXX knots 86 Report at Level (alt) Reporting
at Level XXX XXX 92 Traffic Delay estimate not used in this format
is XXX 96 Turn Left to Turning Left to XXX XXX heading heading 98
Turn Right to Turning Right to XXX XXX heading heading
______________________________________
Without going into detail herein, it is further to be noted that
the inclusion of specific alpha capabilities permits modification
of standard messages and also emergency messages such as might be
required should the pilot be forced to undertake a collision
avoidance course change. Also, because the messages are so short,
rather than employ a back space key, when an entry error is made
the entire message may be eliminated by depressing a cancel key.
Since all of the standard messages as noted above start with
alphas, but may end with numerics, a dash or space key is provided
to permit the generation of multiple message units. In the
embodiment being described, the space key serves as an automatic
shift key to return the alphas for the start of the next message
unit.
Referring now to FIGS. 2 and 3, circuitry in accordance with an
embodiment of the invention intended for use in an air traffic
control environment is shown in block diagram form. The circuitry
of FIGS. 2 and 3 illustrates the principals of double keying and
the logic required to implement this keying technique. In FIG. 2 a
keyboard 10, which may be arranged in the same manner as the
keyboard of FIG. 1, is used to enter a message in the logic
circuitry. The entered message is presented on a printer or a
volatile display 12 in real time for proofreading and is
simultaneously stored in binary form in a storage device 14 so
that, when proofreading is completed, the message may be
transmitted at high speed to a remote terminal. The transmission
may, of course, be by radio waves and an exemplary remote terminal
is depicted in FIG. 3. The received message may be used to activate
a speech synthesizer 16 in the remote terminal which then
pronounces the message at a normal speaking rate.
In the operation of the embodiment of FIGS. 2 and 3, the first
key-press is encoded into binary form in a twelve line to binary
encoder 18. The encoded signal commensurate with the first
key-press is thereafter stored in a first four bit latch 20. The
second key stroke is encoded by encoder 18 and stored in a second
four bit latch 22. The eight bits of data thus generated and stored
in latches 20 and 22 are presented to a read only memory 24 which
adjusts the dual binary code to a code compatible with the display
device 12 and voice synthesizer 16. The words or characters are
stored and displayed on a real time basis for proofreading before
transmission, under the control of display storage and control
circuit 26, and are simultaneously stored in a first-in first-out
(FIFO) register which comprises storage device 14. Each entry into
FIFO register 14 increments a counter 28 which counts the number of
entries. The counter 28 will be counted down to zero as data are
taken out of FIFO register 14 for transmission. When a complete
message is entered, a transmission button located remotely of the
keyboard 10 is pressed thereby generating a signal which clears the
display, if display device 12 is a volatile display rather than a
hard copy printer, and turns on a parallel-to-serial converter 30
and associated transmitter 32. The "transmit" signal also initiates
the operation of a further counter 34 which controls a
pre-programmed identification message read only memory 36. Counter
34 is incremented with each word transmitted until the complete
identification message is transmitted. An AND/OR logic selector
array 38 then selects the output of FIFO register 14 and delivers
the keyboard-entered message from storage device 14 to converter 30
for transmission. Each word transmitted decrements the word counter
28 until it reaches zero, commensurate with complete message
transmitted, at which time the counter 28 causes the generation of
a control signal which results in converter 30 and transmitter 32
being turned off and the system readied for the next data
entry.
The above briefly described entry, storage and transmission
circuitry will now be described in greater detail. Before using the
system, a "clear" button 38 is depressed to generate a signal
which, under the command of steering logic 40, initializes the
system. The "clear" switch 38 will typically be located remotely of
the keyboard and the signal generated thereby will result in the
following functions being accomplished:
1. Clear the display storage and control circuit 26 thus also
clearing display 12;
2. Clear the FIFO register 14 thereby also clearing the
parallel-to-serial converter 30;
3. Reset the up/down message word counter 28 to zero thereby also
setting the output of a zero detector 42 to zero;
4. Reset the "message present" register 44 to the "message not
present" state;
5. Reset a transmit register 46 to the "not transmit" state;
6. Reset a "number next" register 48 to the "no number next" state;
and
7. Reset the steering logic 40 to accept the first key stroke of a
two-key stroke input character.
8. Reset the preprogrammed message word counter 34 to zero.
To enter a two-key stroke character, which will typically
correspond to a spoken word from the voice synthesizer 16 of FIG.
3, any one of the 12 keyboard keys other than the space key is
depressed. The 12 lines of data from keyboard 10 are encoded by the
12 line-to-binary encoder 18 and presented at the inputs of the two
four-bit latches 20 and 22. The 12 line to binary encoder 18 may,
for example, comprise a plurality of RCA type CD4002A and CD4011A
logic gates interconnected to assign a unique binary code to each
input line while the four-bit latches 20 and 22 may comprise RCA
type CD4042A quad latches.
When the first key is depressed a key press detector circuit 50
provides an input signal to steering logic 40 via a delay circuit
52. The purpose of the delay imparted by circuit 52 is to allow the
encoded information to settle at the inputs of the latches 20 and
22 prior to the appropriate latch or latches being clocked by an
output signal provided by steering logic 40. The clock signal
provided by steering logic 40 will cause the four-bit signal
commensurate with the first key depressed to be temporarily stored
in latch 20. The key press detector 50 may also be an RCA type
CD4002A and CD4011A logic gate array arranged as an "OR" function
of the 12 key lines and the delay circuit 52 may comprise an RCA
type CD4013 flip-flop circuit or equivalent. The steering logic 40,
which provides alternate clocking signals for latches 20 and 22,
may comprise an RCA type CD4013A flip-flop, RCA type CD4011A and
type CD4001A gates and RCA type CD4009A inverters interconnected to
give the following performance. The "clear" signal from switch 38
will set the flip-flop, which is connected in a toggle mode,
whereby the flip-flop is ready to receive the first key stroke. A
subsequent signal from delay circuit 52 toggles the flip-flop and
thus sends a positive voltage level change to latch 20. Another
signal from delay 52 toggles the flip-flop thereby sending the
positive signal to latch 22. The next signal from delay 52 will
cause, in the same manner, the signaling of latch 20 again. This
action continues as two-keystroke characters are entered. If the
space key is depressed, both latches are signaled when delay 52
causes the flip-flop to be toggled thereby entering a space. The
space key generated signal also sets the flip-flop to be ready for
a subsequent "first" key stroke. Similarly, a logic "high,"
indicative of "number next," from register 48 will enable both
latches to be signaled when delay 52 signals the flip-flop.
The system remains in the above described state until a second key
depression is sensed. The second key stroke is encoded in the same
manner as the first and is presented to the inputs of latches 20
and 22. The second key stroke is also detected by the key press
detector 50 which, after the delay imparted by delay circuit 52 in
the interest of allowing the data to settle at the inputs of the
latches, signals the steering logic 40 which clocks latch 22 and
stores the second key stroke therein. At this stage, the two
latches 20 and 22 hold eight bits of data which are uniquely
defined by the two key strokes and these eight bits are
individually presented to the input of the read-only memory input
converter 24. The read-only memory code converter 24, which may
comprise a plurality of Intel type 1702 programmable read-only
memories, transforms the unique input data into a unique coded word
address which is recognized and used by the voice synthesizer and
the real time display 12.
The signal which strobes or clocks latch 22 after the second key
stroke also, after a delay imparted by circuit 54, clocks the FIFO
storage register 14, the display storage and control circuit 26 and
the up/down message word counter 28. The delay circuit 54, which
may comprise an RCA type CD4013A flip-flop, imparts a time delay
which allows the output data from code converter 24 to settle at
the inputs to the FIFO storage register 14 before being clocked
into the storage register. The FIFO storage register 14 may, for
example, comprise a plurality of Fairchild type 3341 storage
registers while the up/down message counter 28 may comprise a
series of cascaded RCA type CD4029A counters. The display storage
and control circuit 26 will be commensurate with display 12 and the
two units will typically be acquired as a single commercially
available display unit.
After being clocked by the delayed latch 22 strobing pulse, FIFO
storage register 14 will have the first eight-bit word stored in
its first storage location. The display storage and control circuit
26 also stores the first eight-bit word and displays the symbol or
word on the display 12. The up/down message word counter 28
increments each time a word is entered into the FIFO storage
register 14. A zero detector 42 connected to counter 28 changes
state when the up/down counter 28 is clocked. Zero detector 42 may,
for example, comprise a series of RCA type CD4002A and CD4011A
gates connected to perform a "NOR" function whereby detector 42
will provide a "high" output when the binary output of counter 28
is zero and a "low" output at all other times.
Subsequent to completion of the operations described above, the
steering logic 40 is now ready for the first key press of another
two-keypress entry. If the next key press is a space key, the
steering logic is signaled directly via conductor 39 and both of
latches 20 and 22 are strobed thereby storing the binary
representation of the space key in both latches. The logic then
proceeds as if two keys had been sequentially depressed and stores
a space code in the FIFO storage register 14 and the display
storage and control circuit 26; display device 12 thus displaying a
space.
After depression of the space key, the steering logic is again
ready for the first key stroke of a two key stroke pair. If the two
key strokes of a pair define a word which in the specialized usage
indicated above is always followed by a number, this fact will be
detected by read-only memory 24 as a consequence of its
programming. Read-only memory 24 will, accordingly, recognize the
combinations which are to always be followed by numbers and will
generate a signal commensurate with this information for
application as the data input to a "number next" register 48. The
"number next" register 48 has applied, as control inputs thereto, a
signal generated by depression of the space key and the doubly
delayed output commensurate with the strobing of latch 22; the
second delay being imparted by delay circuit 58 which may comprise
an RCA type CD4013A flip-flop. The "number next" register 48 may
comprise merely an RCA type CD4013A flip-flop circuit which is
sampled by the doubly delayed strobe pulse from the delay circuit
58. When sampled, register 48 transfers the data input from
converter 24 to its output terminal thereby signaling the steering
logic that the next key presses are to be treated as space key
presses and stored in both latches. The information transferred
from the input to the output of "next number" register 48 is also
fed back to the input of code converter 24 and signals the code
converter that the eight lines of input information generated by
the strobing of both of latches 20 and 22 is not a normal double
key press but rather a number whose value is determined by the
redundant information contained in both of latches 20 and 22. The
delay imparted by circuit 58 will be sufficiently long to insure
that the input address of code converter 24 does not change until
the eight-bit word from the code converter read-only memory has
been stored in both FIFO storage register 14 and display storage
and control circuit 26.
Each key stroke after an entry which is determined as having
"numbers follow it" by the code converter-read only memory 24 is
stored in the above described manner after a single key press until
such time as the space key is pressed. The depression of the space
key, in the manner described above, enters a space into FIFO
storage register 14 and display storage and control 26 and resets
the "number next" register 48. This action, in turn, returns the
steering logic 40 to its normal routine of entering two key
strokes.
The above described process of entering information continues, each
character incrementing the up/down message word counter 28 as a
word is entered into the storage register 14, until the complete
message has been entered. After the complete message has been
entered, the operator proofreads the message on display 12 and
transmit it by depressing the transmit button 60. The momentary
closing of the transmit switch 60 sets the "message present"
register 44 to the "message present" state and sets a message
control register 62 to the "preprogrammed message" state. The
setting of message control register 62 signals the AND/OR select
network 38 to gate a preprogrammed message to the transmitter in
the manner to be described below. The message present register 44
and message control register 62 may each comprise an RCA type
CD4013A flip-flop circuit. The AND/OR selector network 38 may
comprise a pair of RCA CD4019A gates and a CD4009A inverter
connected so as to transfer either the eight lines of data from
register 14 or the eight lines of data from ROM 36 to the
parallel-to-serial converter 30 depending on the logic state of the
data select line from message control register 62.
The state of message control register 62, in addition to being
applied as a control input to AND/OR selector network 38, is
delivered as an input to a clock distributor 64. The clock
distributor 64, which may comprise an array of RCA type CD4011A
gates, type CD4009A inverters and an RC differentiator circuit.
Distributor 64, upon receipt of a signal from register 62
commensurate with "transmit signal being received," provides a
"clock out" signal to register 14. This "clock out" signal causes
the first character entered from the keyboard to be transferred to
the output of register 14. The output of distributor 64, by
application to counter 34, also enables further signals from
converter 30 to pass through a counter 34. However, after a further
signal from register 62, indicative of "preprogrammed message
transmission completed," the signals from converter 30 are passed
to register 14 to "clock out" the register and to count message
counter 28, rather than counter 34, down until the complete message
is transmitted. To describe the operation in more detail, clock
distributor 64 generates signals for clocking the preprogrammed
identification word counter 34 and for resetting message counter 28
to zero. However, clock distributor 64 does not provide output
signals until being enabled by an output from the
parallel-to-serial output converter 30. The transmit signal
generated by the closing of switch 60 is delayed, by means of a
delay circuit 66, to insure that the message present register 44
and the message control register 62 are set correctly and the
transmit signal is thereafter employed to activate the transmit
register 46. The activation or setting of transmit register 46
enables the parallel-to-serial converter 30 which, in turn, gates
clock distributor 64 thereby permitting the clock distributor to
send one clock pulse to the preprogrammed identification message
word counter 34. The clock pulse applied to counter 34 from
distributor 64 allows the preprogrammed identification word counter
to count to binary one and the output of counter 34 is presented at
the address input of the preprogrammed identification message read
only memory 36.
Read only memory 36 is programmed with a unique identification
message, for example an aircraft flight number and other
identifying information, in the form of a series of words stored in
such a manner that the words to be transmitted sequentially are
stored with addresses in a binary count mode. Thus, the first
identification word has binary address number one, the second word
has binary address number two, etc. through address word N which is
the last word in a preprogrammed identification message which has
binary address N. To briefly describe the transmission of the
identification message, the read only memory 36 will present
identification message word number one through the AND/OR select
gate array 38 to the transmitter 32 via the parallel-to-serial
converter 30 and a MODEM (modulator/demodulator) which will be
associated with transmitter 32. When the transmitter is ready to
transmit the next word, the parallel-to-serial converter 30 signals
clock distributor 64 which sends a second clock pulse to message
counter 34. The message counter thereupon addresses identification
message word number two in read only memory 36 and causes this word
to be presented to the transmitter in the above described manner.
This mode of operation will continue until identification message
word number N + 1 is addressed in read only memory 36 by counter
34. The address commensurate with identification message word N + 1
is recognized by an "end of preprogrammed message" detector 68
which signals message control register 62 that the identification
message has been transmitted. The message control register 62 is
thereupon reset and, in turn, gates clock distributor 64. This
action causes the clocking pulses generated by distributor 64 to be
switched from the input to counter 34 to the clock down and clock
out inputs respectively of up/down counter 28 and FIFO storage
register 14. The switching control signal from message control
register 62 is, in addition to application to clock distributor 64,
applied to the data select input of AND/OR selector network 38 and
causes network 38 to switch the output of storage register 14 to
the transmitter. The first eight-bit keyboard character is now
presented to the MODEM in the transmitter 32 via the
parallel-to-serial converter 30. The converter 30, when the
transmitter has completed the transmission of the first eight-bit
word, will signal clock distributor 64 which sends a further clock
pulse to up/down counter 28 and register 14. The up/down counter is
decremented one binary count and the second keyboard entered
eight-bit word is presented to the transmitter. This sequential
indexing and transmission of the keyboard entered message continues
until the last word of the message has been transmitted as
indicated by up/down counter 28 reaching zero. The zero state of
counter 28 is detected by zero detector 42 which again changes
state thereby resetting the "message present" register 44 to the
"message not present" state. The resetting of register 44, in turn,
causes the transmit register 46 to be reset to the "not transmit"
state thereby turning off transmitter 32.
In one embodiment of the invention the identification word counter
34 comprises an RCA type CD4024A binary counter and the programmed
identification message read only memory 36 is an Intel type 1702
programmable ROM. The end of preprogrammed message detector 68
comprises an array of RCA type CD4002A gates, type CD4011A gates
and type CD4009A inverters interconnected to give a "high" output
to the message control register 62 when counter 34 contains the
address of preprogrammed identification message word N + 1, and a
"low" output at all other times. The parallel to serial converter
30 and transmitter 32 comprises a Motorola Model No. MC2257L
transmitter used in association with any commercially available
MODEM. The delay circuit 66 is identical to delay circuit 54 and
the transmit register 46 comprises merely an RCA type CD4013A
flip-flop circuit.
Upon completion of the message entry and transmission cycle, as
described above, the system must be made ready for another cycle.
This may be accomplished by depressing a "clear all" key 70 or,
alternatively, the "transmitter-off" signal from transmit register
46 may be utilized to clear the system; for example in the same
manner as shown with respect to the display storage and control
circuit 26.
Referring now to FIG. 3, the message receiver system comprises a
receiver 80 which includes a serial-to-parallel converter. Receiver
80 may, for example, comprise a Motorola Model No. MC2254L terminal
receiver. The received message is translated from
serial-to-parallel format and eight lines of data are presented by
receiver 80 to the input of a first in first out (FIFO) register
82. As each word is entered into FIFO register 82, an up/down
counter 84 is clocked up one binary count. Subsequent to the
clocking of counter 84, the voice synthesizer 16 is triggered and,
as it finishes a word, the "finished" pulse will be employed to
count down counter 84. The "finished" pulse from synthesizer 16
also, through a delay, causes retriggering of the synthesizer. This
action continues until the up/down counter 84 returns to the zero
state commensurate with the message being completely read-out of
FIFO storage register 82 at which time the synthesizer trigger
pulses are terminated.
To describe the receiver system in more detail, the operation of
the receiver starts with a transmitted message activating receiver
80 which takes the incoming eight-bit serial words and converts
them to eight-bit parallel words. Receiver 80 also generates a
"character ready" pulse when a complete character has been
received. The eight-bit parallel words from receiver 80 are
presented to the input of FIFO register 82 which may comprise a
plurality of Fairchild Model 3341 storage registers. The "character
ready" pulses are applied to the "clock in" input to register 82
and cause the storage register to store the eight-bit words in
sequential storage locations. The "character ready" pulse is also
employed to clock up the up/down word counter 84, which may
comprise an RCA type CD4029A binary counter, each time a character
is ready and entered into register 82. The first "character ready"
pulse commensurate with a transmitted message is also employed to
turn on a message present register 86. The message present register
may comprise merely an RCA type CD4013A flip-flop circuit. A signal
commensurate with the setting of message present register 86 is
capacitively coupled, via a delay circuit 88 which imparts
sufficient delay to allow the first few words transmitted to settle
in storage register 82, to the "clock out" input of register 82 via
OR gate 96. The clocking of register 82 presents the first
character entered into the first in-first out storage register at
the input of the voice synthesizer 16. Delay circuit 88 may
comprise merely an RCA type CD4013A flip-flop circuit. The delayed
signal commensurate with the setting of message present register 86
is also applied to an "enable" gating circuit 90. Gating circuit 90
may comprise an array of RCA type CD4011A gates, a type CD4009A
inverter and an RC differentiator circuit. When the data line from
delay 88 goes "high," gating circuit 90 sends a pulse to
synthesizer 16 and counter 84. During the time the input to gating
circuit 90 is "high," signals coming from delay 94 are passed
through circuit 90 to synthesizer 16 and counter 84. When the input
from delay 88 is returned to a "low" state, gating circuit 90
blocks the signal from delay 94. Thus, the "start" command from
gating circuit 90 allows synthesizer 16 to speak one word
determined by the eight-bits of input information. The start
command also clocks down one binary count from up/down counter 84
each time it activates the voice synthesizer. The word is, of
course, generated by means of a speaker 92 associated with
synthesizer 16. The voice synthesizer may be a commercially
available device presently available from McDonnel-Douglas
Electronics Corporation and other sources.
Upon completion of each word the voice synthesizer generates a
"ready next word" signal which is applied to FIFO storage register
82 via OR gate 96, and also to a delay circuit 94. The "ready next
word" signal thus causes storage register 82 to present the next
word that has been entered therein in sequence to the voice
synthesizer input. The delay circuit 94, which may be identical to
delay circuit 88, provides time for the data from storage register
82 to settle at the voice synthesizer input before permitting the
synthesizer to retrigger itself via gating circuit 90. This action
will continue with data loaded into the FIFO storage register 82
from receiver 80 being taken out of the storage register by the
voice synthesizer until the up/down counter 84 reaches zero. The
counter 84 will reach zero when the complete message has been
generated by the voice synthesizer because the synthesizer has a
much slower data rate than the transmitter and receiver. A zero
detector 92, which may comprise an array of RCA type CD4002A and
CD4011A logic gates interconnected to perform a "NOR" function.
Zero detector 92 senses the condition of zero count in up/down word
counter 84 and generates a control signal for the message present
register 86. That is, detector 92 provides a logic "high" output to
message present register 86 when the output of counter 84 is a
binary zero and provides a logic "low" at all other times. The
message present register 86 thereupon, via the delay 88, interrupts
the next "word ready" signal from the voice synthesizer by
resetting gating circuit 90 and thus stops the self-triggering of
the voice synthesizer. Accordingly, the sound generation is
terminated and the system remains ready to receive the next
transmitted message. Voice synthesizer 16 may, of course, be
replaced by or parallelled with a visual and/or hard copy display
device.
The embodiment of the invention described above is a rather complex
system specifically intended for use in an air traffic control
environment. It will be obvious to those skilled in the art that
various modifications and substitutions may be made, without the
exercise of invention, in the interest of utilizing the invention
in less demanding environments. Accordingly, it is to be understood
that the present invention has been described by way of
illustration and not limitation.
It should also be obvious that by the use of a minor change in the
ICAO phonetic alphabet involving the substitution of such words as
"George," "Isaac," "Larry" and "Zebra," respectively, for "Golf,"
"India," "Lima" and "Zulu," sequential keying of the first two
letters of the words of this revised vocabulary on the existing
Bell Touchtone Keyboard yields combinations which uniquely define
the desired letters. This permits the use of telephone lines for
the transmission of hard copy or for computer interrogation with no
requirement for special equipment at the originating end of the
system.
* * * * *