Electronic Voice Annunciating System Having Binary Data Converted Into Audio Representations

Abstract

A voice annunciating system having an electronic memory for storing digital data representative of the analog audio signal of a plurality of predetermined sound components, selected series of said data being applied from said memory to a digital to analog converter adapted to produce an audio signal corresponding to the digital data applied thereto, by means of a control logic. The control logic is operative in response to an actuating signal associated with the desired message. Substantially all redundancy is eliminated from the digital data stored in the memory, said control logic being adapted to repetitively apply individual sound components or series of sound components to the digital to analog converter for reconstructing the desired message.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to systems for providing prerecorded voice messages consisting of instructions and/or warnings in response to actuating signals. Conventional voice annunciating systems generally utilize magnetic tapes, drums or discs for the storage of the desired messages and utilize conventional playback arrangements. However, the use of such conventional systems in a number of applications has presented substantial difficulties due to the environmental, weight and size limitations imposed by such applications. Thus, conventional arrangements use motors and drive mechanisms which are subject to wear during normal use and to failure in severe environments. Magnetic tapes tend to become brittle at low temperatures and to become elastic at high temperatures, resulting in severe distortion and malfunction.

One important application of voice annunciating systems would be in voice warning systems for use in aircraft to warn of equipment failure. Since environmental, size or weight considerations frequently preclude the use of conventional voice warning systems in aircraft, designers have turned to visual or tone warning arrangements. However, such arrangements can fail to attract the attention of the pilot or operator of the vehicle or device in which they are installed due to said pilot's or operator's concentration on his normal operating duties. Thus, it has been found that tone signals and lights are often ignored by pilots who continuously fly heads up. Further, tone signals and lights are incapable of advising the pilot or operator of the action to be taken in response to the warning, while such instructional material can be incorporated into a voice annunciating system. By providing an electronic voice annunciating system, of minimum size and weight, rugged construction, and without moving parts, the foregoing disadvantages of the conventional arrangements are avoided.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the invention, a voice annunciating system is provided which includes electronic memory means for storing digital data representative of the analog audio signal of a plurality of predetermined sound components. The stored digital data consists generally of the nonredundant sound components of the message to be produced. Digital to analog converter means is operatively connected to said memory means for producing an audio signal corresponding to the digital data applied thereto from said memory means. Control logic means is operatively connected to said memory means for applying selected series of said sound component digital data from said memory means to said digital to analog converter means. The control logic means is operative in response to actuating signals applied thereto, the selected series of sound components defining words in the message associated with said actuating signal.

The control logic means is adapted to repetitively apply selected sound components from said memory means to said digital to analog converter means to reconstruct redundancies eliminated from the stored digital data representative of particular sounds present in the message. In addition to repetitive sound components present in individual sounds, redundancies in sounds and words appearing in various positions in a single message or in a plurality of messages may be eliminated from the digital data stored in said memory means. In such a case, the control logic means according to the invention would be adapted to reconstruct the message from the stored data by repeating portions of said data where necessary. The digital data stored in the memory means may consist of a library of words which in various combinations produce a plurality of messages, or a library of sounds which, in various combinations, define a plurality of words, said words defining a plurality of desired messages.

The electronic memory means preferably comprises a nondestructive read-only memory. Further, the control logic means is preferably provided with priority decision logic means for receiving a plurality of actuating signals each associated with a different message and selecting one of said messages having the highest priority for transmission. Said actuating signals may be responsive to the status of sensors or to manually actuated signals. Messages associated with sensor signals may be descriptive of the status of said sensors and/or include instructions for responding to said status.

In other embodiments, monitor means may be provided adapted for converting the output of an optical character reader or a teletype to voice actuating signals whereby the voice annunciator produces the voice messages read by said optical character reader or transmitted by said teletype signal.

Accordingly, it is an object of this invention to provide a voice annunciator system of minimum size and weight and maximum resistance to environmental conditions, particularly adapted for use in aircraft and related applications.

Another object of the invention is to provide a voice warning system having a plurality of messages recorded in digital form in an electronic, nondestructive, read-only memory.

A further object of the invention is to provide a voice annunciator system wherein substantially all of the redundancies in the message to be produced are eliminated from the stored data.

Still another object of the invention is to provide a voice annunciator system which will be responsive to actuating signals representative of the status of a plurality of sensors while only transmitting the highest priority message associated with said actuating signals.

Another object of the invention is to provide a voice annunciator system adapted for use as a voice warning system capable of transmitting both warnings and instructions for responding to said warnings.

A further object of this invention is to produce a voice annunciator system responsive to the outputs of optical character readers or to teletype signals to produce voice messages corresponding to the message being scanned or transmitted.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a block diagram of the electronic voice annunciator system according to the invention;

FIG. 2 is a wave form diagram of a typical speech sound;

FIG. 3 is a block diagram of one embodiment of the control logic according to the invention; and

FIG. 4 is a logic diagram showing the operation of one embodiment of the control logic according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, the electronic voice annunciator system 10 depicted includes control logic 12 operatively connected to memory 14 through line 16 to apply selected digital data stored in said memory through line 18 to digital to analog converter 20. Stored within memory 14 is digital data sufficient to produce any one of the desired voice messages when a selected series of said digital data is sequentially applied to digital to analog converter 20 which produces an analog voltage at its output directly proportional to the digital code applied thereto. The series of analog voltages produced by said digital to analog converter is applied along line 22 to sample and hold circuit 24 adapted to produce a continuous varying analog signal which is strictly a function of the final analog voltage associated with each element of digital data and is not affected by any logic transitions during normal operation.

Any of the conventional digital to analog converter and sample and hold arrangements may be utilized in the system according to the invention. For example, a ladder network may be utilized as digital to analog converter 20, but the system according to the invention is not limited to any particular digital to analog converter or sample and hold circuit. Timing for sample and hold circuit 24 is provided from control logic 12 through line 26.

The output of sample and hold circuit 24 is preferably applied to filter 28 through line 30, said filter being adapted to eliminate all extraneous frequency components outside of the desired audio passband which are caused by the process of reconstructing the audio signal. For example, an active low-pass filter may be utilized. The output of filter 28 is preferably passed along line 32 to a buffer amplifier 34 at which audio output 36 is taken. Said audio output may be applied to one or more speakers which may, if desired, be located in remote locations. The system operates in response to actuating signals applied along line 37 to control logic 12.

Said voice actuating signals are preferably received from monitor 38 which can take any one of a plurality of forms depending on the application of the voice annunciator system according to the invention. For example, monitor 38 may be connected, along lines 39 to a plurality of sensors such as thermocouples, in which case the voice actuating signal would be representative of the status of said sensors to produce a corresponding warning and/or instructional message. In another arrangement, monitor 38 could be provided with means for manually selecting one of a plurality of voice actuating signals to transmit any one of a corresponding plurality of voice messages. Examples of the latter arrangement might be a voice annunciator system incorporated in an aircraft to transmit messages such as "no smoking" and "fasten safety belts" to the passenger compartment thereof.

In other embodiments, monitor 38 could be connected along lines 39 to receive the output of an optical character reader or a teletype signal. When so connected, said monitor would be adapted to convert said optical character reader output or said teletype signals to voice actuating signals for the production, by the voice annunciator system according to the invention, of the voice messages read by said optical character reader or transmitted by said teletype signal. Monitor 38 of such embodiments would include code converting means for converting the signals applied along lines 39 to codes compatible with the system according to the invention, register means for storing said signals until the stored signals define a word or phrase from the library of words or phrases which the voice annunciator system of such embodiments would be designed to produce, and comparator means adapted to compare the stored signals in said register means with said system library and for producing the appropriate voice actuating signal for transmission along line 37 to control logic 12. For example, in the case of an optical character reader said register means would preferably store the converted signal representative of a sequence of letters until said sequence defines a word present in the system library, at which time, the appropriate voice actuating signal would cause the production of that word at the audio output in the manner described above. As used herein, for example, the term "word" includes numbers, so that the arrangement would produce, a voice message corresponding to a series of numbers transmitted by a teletype signal.

In still another embodiment the voice annunciator system according to the invention could be connected to a digital computer through monitor 38, said system being adapted to produce selected voice messages in response to signals applied to monitor 38 by said digital computer. Accordingly, the voice annunciator system according to the invention is adapted for a wide range of applications where it is desired to produce a voice message without resorting to the conventional magnetic tape, drum, or disc arrangements.

The arrangement according to the invention is particularly adapted to take advantage of certain characteristics of the messages normally transmitted by voice annunciator systems and of speech sound in general. It has been found that most discrete sounds utilized in speech contain a redundant repetition of the same sine wave pattern over the duration of several tenths of a second. Thus, having reference to FIG. 2, the sine wave representation 40 of a typical sound consists of the repetition of a series of uniform sound components 42. While this redundance is required to allow time for mental pattern recognition by a human listener, such redundance need not be stored in the memory 14 so long as the basic pattern of each sound component 42 is preserved along with the number of times that said pattern is repeated in the sound to be recorded. Further economies of storage can be achieved by noting that where a plurality of messages are to be stored, certain words are usually present in more than one message. This redundancy can also be avoided in the data stored in the memory. Further, certain messages require the repetition of a particular phrase a predetermined number of times. Again, it is merely necessary to store the phrase along with the number of repetitions thereof required. Still a further economy in required memory capacity, can be achieved by storing a library of voice sounds such as vowel and consonant sounds rather than a library of words. In this manner, each word in the message to be transmitted would be assembled by sequentially transmitting from memory 14 the sounds making up that word. Of course redundancies within each sound would be eliminated as described above. However, this alternate embodiment of the arrangement according to the invention, while generally reducing required memory capacity does have the disadvantage that words reconstituted from mere speech sounds tend to lack the tone quality and accent of real speech and may present difficulties in comprehension. On the other hand, a system based on a library of words recorded and converted to the stored digital data in the manner more particularly described below, presents a more accurate representation of human speech, and is more likely to result in the proper response from the pilot or other operator of the system, when applied to a voice warning system.

In order to take advantage of the above-described economies of storage, control logic 12, as more particularly shown in FIG. 3, includes a message format controller 44. Said message format controller controls the identity of the elements of digital data stored in memory 14 applied to digital to analog converter 20 and the sequence of such application. When a particular voice actuating signal is applied through priority decision logic 46 and line 48 to message format controller 44, said message format controller identifies the particular message associated with that actuating signal and provides the sequential commands to memory 14 which apply the required data to said digital to analog converter. The logic of message format controller 44 is arranged to repeat the digital data representative of each sound component the number of times necessary to reconstruct the original voice sound, and in like manner is adapted to repeat the sequence of sound component digital data required to repeat particular words or phrases as determined by the selected message.

Control logic 12 also includes system timing generator 50 connected along lines 52 to sequence controller 54 to provide basic system timing to insure accurate reconstruction of the audio voice signal in the same phase relationship as the originally recorded audio message. Sequence controller 54 controls the sequential operation of priority decision logic 46 through line 56 and message format controller 44 through line 58. Line 60 is provided between said message format controller and sequence controller to provide a signal to said sequence controller upon the completion of a message. Sequence controller 54 provides timing signals along line 26 to sample and hold circuit 24.

Priority decision logic 46 is incorporated in the embodiment of the arrangement shown in the drawings in recognition of the fact that, in certain applications, such as voice warning systems, all messages will not have the same desired importance. For example, when applied to aircraft, an engine fire would have an extremely high priority when compared with a subsystem failure in the navigation system. Accordingly, the priority decision logic is adapted to scan the voice actuating signals at line 37 to select and transmit to message formal control 44, only that voice actuating signal having the highest priority. This arrangement would permit the interruption of a lower priority message to enable the immediate transmission of a message of higher priority. If desired, priority decision logic 46 may be dispensed with, in which case the message format controller 44 would be responsive to the various voice actuating signals in the order of receipt. Further, priority decision logic 46 may be incorporated in monitor 38, if desired, so that only the priority voice actuating signal is transmitted to control logic 12.

In order to provide a better understanding of the operation of control logic 12, reference is had to FIG. 4 which shows a logic diagram of one embodiment thereof. Tracing said logic diagram, line 37 is examined, as represented by logic block 70 to determine at block 72 if a message is called for. If a message is called for, path 76 is followed to logic block 78 at which the priority of the message called for is compared with the priority of the message being played, if any. If the message being played is of a higher priority, the message called for is held in abeyance as represented by logic block 82. However, if the message called for is of a higher priority, or if no message is being played, path 84 is selected and the appropriate signal is applied to message format controller 44 to proceed with the first instruction of the selected message, as represented by block 86. In the interim, the line 37 is continuously scanned as shown by path 74 to detect voice actuating signals and the priority determination is made with regard to each detected actuation signal.

Upon receipt of the command to proceed with the first instruction, message format controller 44 then sequentially applies the appropriate digital data from memory 14, utilizing a logic exemplified by the following. The selected message sequence, as represented by logic block 88, is started to read the first sound component of the message from memory 14 as represented by block 90 and transmit same to digital to analog converter 20. The determination would then be made at decision logic block 92 as to whether this is the last sound component of the sound being produced, which, as discussed above, normally consists of a predetermined number of repetitions of the same sound component. If this is not the last sound component of the first sound of the message, then path 94 is followed back to logic block 90 to repeat said first sound component. This process is repeated until the predetermined number of repetitions have been accomplished.

When, after the last repetition, decision logic block 92 indicates that the last sound component of the first sound has been completed, path 96 is followed to decision logic block 98 which determines if the entire sound is to be repeated, in which case, the logic returns to block 90 along path 100 to repeat said sound. If the sound is not to be repeated again, the logic proceeds along path 102 to decision logic block 104 which determines if this is the last sound of the word to be produced. If the word includes a further sound, the logic proceeds along path 106 to block 108 which commands the reading out of memory 14 of the next sound. This command advances the message sequence of block 88. In effect, digital data at a different address within the memory is applied to the digital to analog converter. Upon the advancement of the message sequence, the logic proceeds along line 110 to repeat the sound component cycle represented by logic blocks 90, 92 and 98 until the second sound is completed. The foregoing sequence of events is repeated until finally, the last sound of the word is reached, at which point the logic follows path 112 from decision logic block 104 to decision logic block 114 which determines if this is the last word of the message.

If the message has more than one word, path 116 is followed to block 118 which inserts the appropriate pause time delay present between words in normal speech. The logic then proceeds to block 120 which commands the reading out of memory 14 the next word in the message and operates to advance the message sequence at block 88 to repeat the above-described cycle represented by logic blocks 90, 92, 98, 104, 108, and 114 to produce the next word. When finally, the last word of the message is reached, this is detected at decision block 114 and the path 122 is followed to block 72 to indicate the completion of the message. The message having the next highest priority is then transmitted from memory 14 to digital to analog converter 20 by means of the above-described logic. The circuitry of the control logic would also provide for the updating of the pertinent decision logic blocks 92, 98, 104 and 114 upon each start or advance of message sequence at block 88. By the foregoing logic, the need for storing redundant sound components, sounds or words in a particular message or group of messages is eliminated.

To further minimize the size and weight of memory 14, said memory is preferably of the nondestructive read-only type. Examples of such memories are wire rope memories, diode matrix arrays and MOS and SOS integrated circuit memory arrays. Such memories have no moving parts, occupy a minimum of space, are of a minimum weight, and can be of extremely rugged construction. Further, the packaging of such memories, and in fact, of the entire system according to the invention, can take any desired shape, thereby offering a substantial advantage for aircraft applications over the known voice annunciating systems, which, due to their use of either magnetic tapes, drums or discs as their storage arrangement and motors to drive said arrangement, can be packaged in only a limited number of configurations.

Because of the read-only nature of the preferred memory, such memories are prewired to incorporate the desired digital data at predetermined addresses. The identification of the minimum digital data to be stored is accomplished as follows. Messages desired to be recorded are first digitized and stored in digital form in a large memory. Such analog to digital conversion is readily accomplished using conventional arrangements. The audio signal representing the message is periodically sampled and the absolute value of the audio signal within each sampling time slot is converted to digital form and represented by a single digital element or word formed of a number of bits. The digitized messages may then be printed out on paper for analysis to eliminate the redundancy and to provide the logic pattern necessary for incorporation within control logic 12 to reproduce the original messages. The resultant minimal data is then wired into the read-only memory.

Instead of analyzing entire messages by the above-described technique, discrete words or even sounds can be so analyzed to form, in the memory, libraries of words or sounds which can be drawn upon by control logic 12 to construct desired messages. The digital data representative of each such word or sound in said libraries would be minimized by removing redundancies in the manner described above. The sequential logic patterns utilized to read each word or message out of memory 14 may themselves be in the form of digital data stored in a further read-only memory forming a part of control logic 12. Said logic pattern digital data may be sequentially read out of said further memory and the remaining portion of said control logic which in turn reads data out of memory 14. Further, in the embodiment adopted for use with teletypes and optical character readers the code representations of the library of words stored in memory 14 can also be stored in a read only memory. Such a memory would be scanned by the comparitor of monitor 38 to identify the words stored in the registers thereof for transmission of the appropriate voice actuating signal.

The electronic voice annunciating system according to the invention is extremely compact, of relatively lightweight, and extremely rugged. Accordingly, it is particularly suited for use in aircraft and other applications wherein factors such as weight, size or resistance to environmental conditions are of primary importance. Further, since the system incorporates no moving parts, an extremely high reliability can be achieved as compared to the reliability of the mechanical arrangements utilizing magnetic tapes, discs or drums. Further, when used for voice warning, the system according to the invention offers substantial advantages over warning systems utilizing lights or tone signals since a voice warning system insures attracting the attention of the operator and may be utilized to provide not only a warning, but also instructions for curing the defect actuating the warning. Finally, the priority decision logic incorporated in the arrangement according to the arrangement permits the operator to identify and direct his attention to the most important defect, a feature not possible if light or tone warning systems are utilized.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

I claim:

1. An electronic voice annunciating system comprising electronic memory means for storing the digital data code converted equivalent to the analog audio signal of a plurality of predetermined sound components; digital to analog converter means operatively connected to said memory means for producing an audio signal consisting of said predetermined sound components converted from the digital data supplied thereto from said memory means; and control logic means operatively connected to said memory means for applying selected series of said sound component digital data from said memory means to said digital to analog converter means, said selected series of sound components defining words in a desired message, said control logic being operative in response to an actuating signal applied thereto associated with said desired message, said control logic means including means for repetitively applying the digital data equivalent to preselected ones of said sound components from said memory means to said digital to analog converter means in producing the sounds defining said words, said repeated sound components representing redundancies in said sounds.

2. An electronic voice annunciating system as recited in claim 1, wherein said memory means has stored therein at least the digital data equivalent to the sound components necessary to define a plurality of messages, said system including priority decision logic means for receiving a plurality of actuating signals each associated with a different message and selecting the one of said messages having the highest priority for transmission.

3. An electronic voice annunciating system as recited in claim 2 wherein at least some of said actuating signals are responsive to the status of sensors, the messages associated therewith being descriptive of said status.

4. An electronic voice annunciating system as recited in claim 3, wherein at least some of said messages associated with sensor status also include instructions for responding to said status.

5. An electronic voice annunciating system as recited in claim 1, wherein said memory means comprises a nondestructive read-only memory.

6. An electronic voice annunciating system as recited in claim 5, wherein said read-only memory has stored therein at least the sound components necessary to produce any one of a plurality of desired messages.

7. An electronic voice annunciating system as recited in claim 1, wherein said memory means has stored therein at least the digital data equivalent to each sound of the desired message less substantially all such digital data equivalent to redundancies in sound components in each such sound, said control logic means being adapted to repetitively apply selected sound components from said memory means to said digital to analog converter means to reconstruct said redundancies in each such sound to form the desired message.

8. An electronic voice annunciator system as recited in claim 1, wherein said memory means has stored therein at least the digital data representative of a plurality of sounds, said sounds, in various combinations, defining a plurality of words, said words defining at least a plurality of desired messages, said control logic means being adapted to sequentially apply the digital data representative of selected sounds from said memory means to said digital to analog converter means to define the desired message.

9. An electronic voice annunciating system for use with an optical character reader as recited in claim 1, including monitor means connected to said control logic means for converting the output signal of said optical character reader to voice actuating signals, said memory means having stored therein at least the digital data equivalent to the sound components necessary to define a library of words, said control logic means sequentially applying digital data representative of words scanned by said optical character reader from said memory means to said digital to analog converter means in response to said voice actuating signals to produce a voice message formed from said scanned words.

10. An electronic voice annunciating system as recited in claim 9, wherein said monitor means stores elements of said optical character reader output signal until said elements define a word stored in said memory means, at which time the appropriate voice actuating signal is produced.

11. An electronic voice communicating system for use with a teletype system as recited in claim 1, including monitor means connected to said control logic means converting teletype signals to voice actuating signals, said memory means having stored therein at least the digital data equivalent to the sound components necessary to define a library of words stored therein, said control logic means sequentially applying digital data representative of the words transmitted by said teletype signal from said memory means to said digital to analog converter means to produce a voice message corresponding to said transmitted words.