CA1319405C - Frequency independent information transmission system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The system is used for transmitting information wherein each possible message unit in a set, (e.g. the alpha-numeric symbol set) is defined by a specific interval (I = f5/fR) and messages are transmitted by conversion to the interval code and for the sending of signals of any two frequencies (f5 and fR) that are related by the specific intervals. The signals are received by a receiver which computes the interval, matches it with the pre-defined message unit interval and outputs that message unit. A
sequence of message units may be sent using a reference frequency signal and a succession of specific signals each related to the reference frequency by the specific interval for that message unit. A computer program can be utilized for automatically encoding or decoding. The system has the advantages that is relatively free of errors caused by long term frequency shifting, allows transmission at any frequency level, and allows interacting communication between stations wherein the transmitters operate in entirely different frequency domains.
In particular, the system is operable to transmit information in the form of interval-coded tones suitable for interpretation by a human listener. Examples of the use of the system include a clock and a voltmeter comprising tone output circuitry.

Description

FREQUENCY INDEPENDENT INFORMATION
TRANSMISSION SYSTEM
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to the transmission of information and is especially concerned with a code transmission system.
Description of the Prior Art Numerous systems for the transmission of information have been proposed. See, for example, U.S. Patents Nos.
3,366,737 issued to Brown, Jr. for "MESSAGE SWITCHING CENTER FOR
ASYNCHRONOUS START-STOP TELEGRAPH CHANNELS", 3,627,951 issued to Batin for "ASYNCHRONOUS CO~MUNICATIONS SYSTEM CONT~OLLED BY DATA
PROCESSING DEVICE", 3,633,172 issued to Eggimann et al. for "MEANS FOR AND METHOD OF ADDRESS-CODED SIGNALING", 3,796,835 issued to Closs et al. for "SWITCHING SYSTEM FOR TDM DATA WHICH
INDUCES AN ASYNCHRONOUS SUBMULTIPLEX CHANNEL", 3,988,545 issued to Kuemmerle ~t al. for "METHOD OF TRANSMITTING INFORMATION AND
MULTIPLEXING DEVICE FOR EXECUTING THE METHOD", 4,154,983 issued to Pedersen for "LOOP CARRIER SYSTEM FOR TELECOMMUNICATION AND
DATA SERVICES", and 4,390,985 issued to Fourcade et al. for "DEVICE FOR THE SYNCHRONIZATION OF DIGITAL DATA TRANSMITTED IN
PACKETS".

~d~

SUMMARY OF THE INVENTION
The present invention i5 directed to a system for transmitting information wherein the information consists of series of specific message units out of a set o~ possible units, (e.g. a word message made out of the 26 letters of the alphabet) and includes the step of defining an interval for each of the members of the set. Then the message is converted into a signal of a reference frequency signal and a series of information signals each having a frequency related to the reference signal's frequency by the interval so defined. Next this message is transmitted. This set of signals can then be translated back to the message by a receiver that compares the received signals to determine their intervals and compares the intervals so derived to the defined interval.
The system may be readily adapted to be machine implemented using a digital computer and encompasses a transmitter and a receiver for carrying out the process.
Since an interval is used, the message can be sent and recogniged despite shifts in frequency from one message to another or despite uniform shifts in frequencies. The system has the following advantages:
The Message-Interval Coding in the system is frequency independent and, hence, portable across the frequency spectrum.
The Message-Interval Coding of the system forms a smart system because a message, identified by a particular interval, can be conveyed at higher or lower frequencies.
The system affords great freedom in hardware design.
The system permits different machines to talk at higher or lower frequencies while conveying the same Interval-Coded Message.
The system makes high-frequency machines compatible with low-frequency machines.
With the Message-Interval Coding of the system, a wide band machine listener is capable of understanding both high-frequency and low-frequency transmitters which convey the same Interval-~oded Message.
The system provides a smart machine transmitter because the 3 j transmitter can convey a particular Interval-Coded Message at higher or lower frequencies.
Furthermore, the transmitter of the system can be employed in another manner to transmit information in the form of Interval-Coded audible tones for direct interpretation by a human listener. When used in this manner, the machine receiver of the system may be omitted. Examples, including a clock and a voltmeter comprising such tone transmitter, are also disclosed.
The system, together with the advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which, like reference numerals identify like elements.

~ 3 ~ ? `j BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a set o~ waveforms useful in explaining the system of the present invention.
FIG. 2 is another waveform illustrating one aspect of the system of the present invention.
FIG. 3 is yet another waveform for illustrating another aspect of the system of the present invention.
FIG. 4 is a table for use with the system of the present invention.
FIG. 5 is a flow chart useful in illustrating the overall operation of the system.
FIG. 6 is a block diagram of a system for producing or transmitting signals constructed in accordance with the system of the present invention.
FIG. 7 is a more detailed flow chart useful for illustrating the operation of the system shown in FIG. 6.
FIG. 8 is a waveform diagram illustrating a feature of the system of the present invention.
FIG. 9 is a block diagram of a receiver system constructed in accordance with the principles of the present invention.
FIG. 10 is a flow chart illustrating the operation of the system shown in FIG. 9.
FIG. 11 is a circuit and block diagram of one particular embodiment for part of the system shown in FIG. 9.
FIG. 12 is a set of waveforms useful in illustrating the operation of the system of the invention.
FIG. 13 is a schematic block diagram of a record/playback unit of the system employing a recording media (such as a magnetic tape).
FIG. 14 is a detailed electrical circuit diagram of the record/playback unit shown in FIG. 13.
FIG. 15 is a block diagram of a clock employing a transmitter system constructed in accordance with the principles o~ the present invention.
FIG. 16 is a block diagram of a measuring device employing a transmitter system constructed in accordance with the principles of the present invention.

~ 3.~
DESCRIPTION OF THE PREFERRED EM~ODIMENT
Referring to the drawings and especially to FIG. 1, the processes of the present invention may be appreciated from the following description with reference to FIG. 1.
It should be noted that while square waves are depicted in the drawings, the principles explained apply to any shaped periodic waveform.
The system or process of the present invention uses the Interval I, between two frequencies of a waveform such as waveforms WR and WS(1) f FIG. 1 to identify specific messages or items of information (e.g. the letter "A") from a table of such messages. These frequencies may be designated fR for a reference frequency and fS for a signal frequency. Then the Interval I may ba defined by the following equation:
I =
fR
Using the usual definition of the periodic T of a wave as the inverse of its frequency (T = l/f) this becomes:
TR DR
I= =
TS DS
where DR and DS represent the duration of a half cycle of the waveform WR or Ws.
Each interval in a table of intervals can be assigned a different specific message. With reference to FIG. 1, then, the two waveforms WR and W5(1) would define an interval:
TR
Is(1) =
S(1) Taking the general case, any waveform WS(N) would define an interval:
TR fS(N) IS(N) TS(N) fR
and by defining a message unit, Nth Message, the two waveforms WR and WS(N) yield this Nth Message unit M(N)- If the value f IS(N) :~ 3 ~
equals Ik in the table, which has been assiyned a specific message member M~, then M(N) equals Mk.
FIG. 4 is one such generalized tabl~. As a concrete example, let us assume we wish to transmit a message using the English alphabet. We could then make up a table such as this:
TABLE I
MESSAGE UNITS INTERVAL
2A (M/24) A 1.000000 B 1.029302 C 1.059463 D 1.090507 E 1.122462 F 1.155352 G 1.189207 H 1. 224053 I 1.259921 J 1.296839 K 1.334839 L 1.373953 M 1.414213 N 1.455653 0 1.498307 P 1.542210 Q 1.587401 R 1.633915 S 1.681792 T 1.731073 U 1.781797 V 1.834008 W 1 . 8g7748 X 1.943063 Y 2.000000 Z 2.058604 10 Space 2.118926 etc.
Thus, a message unit for "Y" could be translated from two waveforms WR and WS wherein the ~requency of WR was 10 XHz and that of WS 20 KHz. Note that ik could also be lKHz and 2KHz or 1.13MHz and 2.26 MHz.
(Of course, in a practical receiver of this system any interval within a range about the above precise values would be accepted as being that interval.) ~0 The waveforms WR and WS(1)~ etc. can be transmitted sequentially as shown in FIG. 2 and even single cycles of the waveforms used as there shown. However, in most practical systems it is preferred that the waveforms WR~ WS(1)~ etc. persist for a number o~ cycles so as to make the detection of them accomplished easily and with less precise equivalence. However, this is not necessary for even as short a duration as one half cycle D~, DSt1), DS(N) can be used as illustrated in FIG. 3.
Again, in this case each message unit is represented by the interval defined by the equation there set out.
Transmitter FIG. 5 shows the steps in practicing the process of the present invention in the conventional computer flow chart manner.
From a start at 12, the first step 14 is to establish the message interval (MI) Table (step 14). The next step 16 is to input specific message units M(l). . . M(N) (for example, the letters and spaces NOW IS THE TIME . . . AID . . . using Table I above.) at step 16 and select the corresponding intervals from the MI
Table o~ stop 14. The final step 18 is to generate the waves WR~
Ws(l~ etc. in accordance with the input of step 16 and when this is done the operation is over at step 20.
A transmitter 21 for carrying out the process of FIG. 5 is ~ 3 ~ ~9 ~ 3 shown in FIG. 6 wherein a microcomputer 22 receives the message units (e.g. through a keyboard) at input 24 and selects the proper intervals from a ~I Table unit 26. (This table may take the form of a ROM chip or any other suitable source). The microcomputer 22 derives a succession of signals for a reference waveform and message waveforms and supplies them to an output 28.
These can be, for example, the duration of half-cycles of the wave~orms DR~ Ds(l) The output 28 feeds a programmable wave generator 30 which produces the output wave WR~ WS(1)~ etc. on its output 32. This latter output 32 may be fed to a suitable transmission vehicle such as a transmission line or optic fiber or broadcast antenna.
This transmitter has been constructed and successfully operated using a BBC Microcomputer Model B. This Microcomputer contains a 6502 CPU and two 6522 Versatile Interface Adaptors, where one of which, the US~R VIA, is already connected to the Model B's USER PORT for user applications. A more detailed flow chart for this particular and currently preferred method of carrying out the invention is shown in FIG. 7.
In this particular case, the microcomputer 22 may serve as not only the microcomputer 22, but by placing the Table MI in its RAM as the table 26, the USER VIA section can be operated as the generator 30 wherein the output waves are obtained across the standard circuit points identified as PB7 and OV at the USER PORT
of this commercially available computer.
The flow chart of FIG. 7 includes a start command 34 which establishes a MI Table at step 36 and accepts input messages at step 38. In response to the first of these steps, it fetches a pre-selected reference D (half-cycle) at step 40 and in the next stage 42, inverts the logic state at the output and starts a countdown on D. Before the conclusion of this countdown it fetches the next signal D (i.e., Ds(l)~ etc.) in function block 44. If this is not the last D fetched (test block 46) the system responds as indicated in block 47 to restart the process of electing the next D. If the answer to test 46 is "yes", the system responds as indicated by logic block 50 to proceed to countdown on the last D and as indicated by block 52 to invert ~31~3.'j logic at the output and proceed to end at 54.
The program for carrying out khis operation is as ~ollows:
Transmitter Proqram I
REM INVENTED BY HO KIT-FUN
REM UNPUBLISHED COPYRIGHT
REM
REM NORTH POINT
REM HONG KONG
REM

90 ?&FE6B=&CO : REM SET USER 6522 AT FREE-RUNNING MODE
92 ?&FE62=&80 REM INITIALIZE OUTPUT (SET PB7 AT HIGH) 94 ?&FE6E=&OO : REM INTERRUPT DISABLED

120 DR=3000 : REM SET REFERENCE "HALF-CYCLE" DURATION, PROGRAMMABLE
130 DELAY%=2 140 DSH%=&ODAO : DSL%=&ODCO : REM LOCATION OF MI TABLE
150 FOR M = 0 TO 31 DEMONSTRATION
180 REM (EACH MESSAGE HAS THE SAME INFORMATION CONTENT
AS 5 BINARY BITS) 200 DS% = INT 2^ (-M/24)*DR : REM COMPUTE SIGNAL "HALF-CYCLE" DURATION

220 REM INTERVALS 2^ (0/24), 2^ (1/24), 2^ (2/24), 2^ (31/24) 230 DS%=DS%-DELAY% : REM DELAY CORRECTION
232 REM TRUE DURATION = PROGRAMMED DURATION + DELAY
235 DSH%?M=DS% DIV 256 238 DSL%?M=DS% MOD 256 300 N=128 : REM TAKE N INPUT MESSAGE UNITS
(N=1,5,16,64 ETC., PROGRAMMABLE) 320 DTA%=&3000 : ?DTA%=N
330 FOR NUM% = N TO 1 STEP -1 340 M=GET : REM SPECIFIC MESSAGE UNIT OF A DEPRESSED
KEY
342 IF M=32 THEN M=27 ELSE M=M-65 350 DTA%? (NUM%)=M

420 FOR PASS = 0 TO 3 STEP 3 430 P%=&ODOO
440 [

500 LDA DSL%
510 STA &FE64 LOAD 16-BIT COUNTER

3 3 ~ ''3 520 LDA DSH% WITH
530 STA &FE65 REFERENCE DURATION
540 LDX DTA~
550 .LOOP LDA DTA%,X

570 LDA DSL%,Y
580 STA &FE66 LOAD 16-BIT LATCH
590 LDA DSH%,Y WITH
600 STA &FE67 SIGNAL DURATION
10 620 .STS BIT &FE6D

690 .STP LDA #&80 700 STA ~FE6B

720 ]

740 CALL &ODOO

The flow chart of ~I~. 7 and this program consist of the procedure used to realize a machine which conveys a message by producing INTERVAL-CODED "HALF-CYCLE" WAVELETS like those shown in FIG. 3. It follows that by generating each of such "HALF-CYCLE" twice one obtains "SINGLE-CYCLE" WAVES like those shown in FIG. 2. And by generating each of such "HALF-CYCLE" several times one obtains WAVE TRAINS like those in FIG. 1.
The output produced by the system of FIGS. 6 ahd 7 is shown in FIG. 8 wherein the output at line 32 is depicted from the reference DR and the DS~1) and DS~2) with the various logic events depicted in their timed relationship to the output.
Receiver Referring to FIG. 9, there is depicted a receiver 60 having an input 62, on which the waveforms WR, WS(1)~ WS(N) are received from a suitable transmission media such as a transmission line or optic fiber or antenna. This input 62 delivers the waveforms to a wave duration measurement circuit 64 which serves to measure the duration D and feeds a succession of duration information on DR, DS(l)' etc. to a microcomputer 66.
An MI Table 68 which is substantially similar to that of the transmitter sending the signals WR~ WS(1)~ etc. is provided and the computer computes the intervals and derives from the table 68 the message unit M(l), . . .M(N). These message units are fed to a suitable output 70 such as a Cathode Ray Tube display or a printer or both.
The MI Table 26 of the transmitter 21 woul~ be one of precise intervals but as stated above the receivPr should recognize calculated intervals within a range of values about the precise values. This can be done by having the program select the closest interval or by having the MI Table 68 at the receiver contain a range. The system currently utilizes this latter approach and has the following MI Table 68 for the receiver 60 for the particular message unit given above:
TABLE II
MESSAGE UNIT INTERVAL BOUNDARY
2^ (M-0.5)/24) -------------------------- O . g85663 -------------------------- 1.014545 -------------------------- 1.044273 -------------------------- 1.074873 --------------------------- 1.106369 1. 13?378 ---------~ ---------- 1.172157 ~------------------------- 1.206504 -------------------------- 1.241857 1.278247 -~------------------------ 1.315702 ~------------------------- 1.354255 1.393938 M

-------------------------- 1.434783 1.476826 ----- ---- -- 1.520100 1.564642 ~ 3 ~
Q

-- -- ---- 1.610490 1.6576~1 - --- - --- 1.706~55 T

- - --~--- -- -- -- 1.756~52 --- -----~------------- - 1.807714 1.860684 W

- - - -- 1.915206 ------------ -- - -- - 1.971326 ----------------- --- 2.029090 -- - - -- - -- 2.088547 Space 2.1497~6 etc.
That is, in the TRANSMITTER 21, the MI Table 26 is in the form o~ message-wave duration correspondence, and in the R~CEIVER
60, the MI Table 68 is in the ~orm of message-interval boundary correspondence.
The MI Table in TABLE I can be an example of 32-state coding, where each message unit has the same information content as 5 binary bits, i.e. l out of 32. From TABLE I it is apparent that similar MI ~ables for coding 4-, 8-, 10-, and 24-state messages, etc. may be used.
The receiver computer 66 may also be a BBC Microcomputer Model B which is programmed in accordance with the flow diagram of FIG. 10 and the program given below. In this case the MI
Table 68 is again held in the RAM.
The receiver 60 may not be easily made from just the aforementioned computer but requires a wave measurement circuit 64. One preferred circuit 64 is depicted in FIG. 11.

s The elements, values and interconnection of the circuit are given in FIG~ 11. The circuit of FIG. 11 is connected to the I/O
port known as the l-MHz Ex~ension Bus of the BBC Microcomputer.
The conductors R/NW, NP, AO, Al, A2, ~. DO, Dl, D2, D3, D4, D5, D6, D7, and G of the circuit of FIG. 11 are respectively connected to R/NW, NPGFC, AO, Al, A2, lMHZ, DO, Dl, D2, D3, D4, D5, D6, D7 and OV of The l-MHz Extension Bus.
In overall operation, the circuit 64 serves to measure the time instant at the occurrence of each waveform transition of the input wave and present this information to the Microcomputer 66.
At the input R of the circuit 64 the received wave W is fed to inverting buffer 71 to produce at its output an inverted wave NW which is inverted once again by inverter 73 to recover an uninverted wave W at the most significant bit D15 of a 16-bit latch 74. By using decoder 76, flipflop 77 and switch 78 the computer 66 selectively feeds the waveform W or NW, alternately, to LE to produce a time-related latching waveform LW, which may be illustrated with FIG. 12. By sensing the HIGH or LOW voltage level of and, hence, transition in the waveform W at D15 the computer 66 (a) initializes LW to HIGH, (b) detects the occurrence of waveform transition in W, (c) takes a latched counter reading at 74 captured from counter 79 by a HIGH-to-LOW
TRANSITION in LW, and (d) resets LW to HIGH to unlatch 74 for another capture. Clock pulses o are provided (e.g. from computer 66) to operate the counter 79 and through inverter 80 to operate switch 78. The captured counter readings obtained in this manner provide information on durations DR, DS(l), etc. of the received ~ 3 ~

waveform W.
Referring to FIG. 10 the program upon start 82 initially establishes the MI Table in its RAM at step 84, e.g. by copying it from a disc drive or other more permanent memory. (In the case of a dedicated receiver this could take the form of a ROM
chip). Thereafter, at block 86, it measures the duration (with unit 64) ~f the received waves and, at block 88, identifies the intervals and message units in accordance with the MI Table and when completed terminates the program at end 89.
10 A suitable program that has been success~ully operated in the aforementioned particular computer is as follows:
Receiver Proqram I

5004 REM P.O. BOX 54504 5050 N=128 : REM NUMBER OF SIGNALS
5060 n=N+l : REM NUMBER OF WAVES
5070 CONSTANT1%=128*256 5080 DIM Ibound(32),DSB%(32),CTIME%(n),DURATION%(N), STORAGE%(N),M(N) 5090 HTIME=&5500 5100 LTIME-HTIME+n+l 5105 STORAGE%=&4000 : REM STORAGAE LOCATION
5108 FOR M=O TO 32:Ibound(M)=2 ~ ((M-0.5)/24):NEXT :
REM INTERVAL BOUNDARIES
5110 W=&FC03 :REM WAVEFORM W
5120 NW=&FC02 :REM WAVEFORM NW
5130 HBYTE=&FCOl :REM 16-BIT LATCH LOCATION
5140 LBYTE=&FCOO :REM 16-BIT LATCH LOCATION
5150 FOR PASS=O TO 3 STEP 3 5160 P%=&DOO
5170 [

5190 LDY#O
40 5200 LDA HBYTE \READ HIGH BYTE OF 16-BIT LATCH

5220 .NWAVE LDA NW \SWITCH TO NW WAVE
5230 .NWATI LDA HBYTE

~ rj 5250 AND #127 5260 STA HTIME,Y

5280 STA ~TIME,Y
5300 CPY #n 5310 BEQ STOPl 5320 .WAVE LDA W \SWITC~ TO W WAVE
5330 .WATI LDA HBYTE

5350 STA HTIME,~

5370 STA LTIME,Y
5390 CPY #n 5400 BEQ STOPl 5420 .STOPl RTS
5430 ]

5450 CALL ~ODOO
5470 REM COUNTER TIME CAPTURED (i.e. CAPTURED
TIME INSTANT ) 5480 FOR Y=O TO n 5490 CTIME%(Y) = (?(HTIME~Y))*256+7(LTIME+Y) 5530 FOR Y=O TO N
5540 DURATION%(Y) = CTIME%(~+l) - CTIME%(Y) 0 5550 IF DURATION%(Y) < O THEN DURATION%(Y) =
DURATION%(Y) + CONST~NTl%

IDENTIFICATION
5560 DSB%(O)= INT DURATION%(O)/Ibound(O) 5562 DSB%(l)= INT DURATION%(O)/Ibound(l) 5564 DSB%(2)= INT DURATION%(O)/Ibound(2) 5565 DSB%(3)= INT DURATION%(O)/Ibound(3) 5566 DSB%(4~= INT DURATION%(O)/Ibound(4) 5570 DSB%(5)= INT DURATION%(O)/Ibound(5) 5572 DSB%(6~= INT DURATION%(O)/Ibound(6) 5574 DSB%(7)= INT DURATION%(O)/Ibound(7) 5576 DSB%(8)= INT DURATION%(O)/Ibound(8) 5578 DSB%(9)= INT DURATION%(O)/Ibound(9) 5580 DSB%(lO~= INT DURATION%(O)/Ibound(lO) 5582 DSB%(ll)= INT DURATION%(O)/Ibound(ll) 5584 DSB~(12)= INT DURATION%(O)/Ibound(12) 5586 DSB%(13)= INT DURATION%(O)/Ibound(13) 5588 DSB%(14)= INT DURATION%(O)/Ibound(14) 5590 DSB%(15)= INT DURATION%(O)/Ibound(15) 5592 DSB%(16)= INT DURATION%(O)/Ibound(16) 5593 DSB%(17)= INT DURATION%(O)/Ibound(17) 5594 DSB%(18)= INT DURATION%(O)/Ibound(18) 5595 DSB%(l9)= INT DURATION%(O)/Ibound(l9) 5596 DSB%(20)= INT DURATION%(O)/Ibound(20) 5597 DSB%(21)= INT DURATION%(O)/Ibound(21) ~ 3 ~

5598 DSB% (22) = INT DURATI ON% ( O ) / Ibound (22) 5599 OSB%(23)= INT DURATION%(O)/Ibound(23) 5600 DSB% (2 ~ ) = INT DURATION% ( O ) / Ibound (24) 5601 DSB% (25)= INT DURATION% (O)/Ibound(25) 5602 DSB%(26)= INT DURATION%(O)/Ibound(26) 5603 DSB% (27) = INT DURATION% ( O) /Ibound (27) 5604 DSB% (28) = INT DURATION% ( O ) / Ibound (28) 5605 DSB% (29) = INT DURATION% ( O ) / Ibound (29) 5606 DSB% (30) = INT DURATION% ( O ) / Ibound (30) 5607 DSB%(31)= INT DURATION%(O)/Ibou~d(31) 5608 DSB%(32)= INT DURATION%(O)/Ibound(32) 6000 FOR Y=l TO N
6010 IF DURATION% (Y) > DS13% ~O) THEN PRINT "ERROR
IN MESSAGE (";Y;")": M(Y)=127:GOTO 8000 6020 IF DURATION%(Y) > DSB%(l) THEN M(Y)=O:GO TO 8000 6030 IF DURATION%(Y) > DSB%(2) THEN M(Y)=l:GO TO 8000 6040 IF DURATION%(Y) > DSB%(3) THEN M(Y)=2:GO TO 8000 6050 IF DURATION%(Y) > DSB%(4) THEN M(Y)=3:GO TO 8000 6060 IF DURATION%(Y) > DSB%(5) THEN M(Y)=4:GO TO 8000 20 6070 IF DURATION%(Y) > DSB%(6) THEN M(Y)=5:GO TO 8000 6080 IF DURATION%(Y) > DSB%(7) THEN M(Y)=6:GO TO 8000 6090 IF DURATION%(Y) > DSB%(8) THEN M(Y)=7:GO TO 8000 6100 IF DURATION%(Y) > DSB%(9) THEN M(Y)=8:GO TO 8000 6110 IF DURATION%(Y) > DSB%(lO) THEN M(Y)=9:GO TO 8000 6120 IF DURATION%(Y) > DSB%(ll) THEN M(Y)=lO:GO TO 8000 6130 IF DURATION%(Y) > DSB%(12) THEN M(Y)=ll:GO TO 8000 6140 IF DURATION%(Y) > DSB%(13) THEN M(Y)=12:GO TO 8000 6150 IF DURATION%(Y) > DSB%(14) THEN M(Y)=13:GO TO 8000 6160 IF DURATION%(Y) > DSB%~15) THEN M(Y)=14:GO TO 8000 30 6170 IF DURATION%(Y) > DSB%(16) THEN M(Y)=15:GO TO 8000 6171 IF DURATION%(Y) > DSB%(17) THEN M(Y)=16:GO TO 8000 6172 IF DURATION%(Y) > DSB%(18) THEN M(Y)=17:GO TO 8000 6173 IF DURATION%(Y) > DSB%(l9) THEN M(Y)=18:GO TO 8000 6174 IF DURATION%(Y) > DSB%(20) THEN M(Y)=l9:GO TO 8000 6175 IF DURATION%(Y) > DSB%(21) THEN M(Y)=20:GO TO 8000 6176 IF DURATION%(Y) > DSB%(22) THEN M(Y)=21:GO TO 8000 6177 IF DURATION%(Y~ > DSB%(Z3) THEN M(Y)=22:GO TO 8000 6178 IF DURATION%(Y) > DSB%(24) THEN M(Y)=23:GO TO 8000 6179 IF DURATION%(Y) > DSB%(25) THEN M(Y)=24:GO TO 8000 ~0 6180 IF DURATION%(Y) > DSB%(26) THEN M(Y)=25:GO TO 8000 6181 IF DURATION%(Y) > DSB%(27) THEN M(Y)=26:GO TO 8000 6182 IF DURATION%(Y) > DSB%(28) THEN M(Y)=27:GO TO 8000 6183 IF DURATION%(Y) > DSB%(29) THEN M(Y)=280GO TO 8000 6184 IF DURATION%(Y) > DSB%(30) THEN M(Y)=29:GO TO 8000 6185 IF DURATION%(Y) > DSB%(31) THEN M(Y)=30:GO TO 8000 6186 IF DURATION%(Y) > DSB%(32) THEN M(Y)=31:GO TO 8000 7000 PRINT "ERROR IN MESSAGE (";Y;")":M(Y)=255:GOTO 8000 8000 STORAGE%?Y = M (Y) 8115 IF STORAGE%?Y=27 THEN PRINT CHR$ (32); ELSE PRINT CHR
(65+STORAGE%?Y);

The computer is programmed with the above program to measure the wave durations by recording the time instants as each transition of the wave occurs. The procedure for measuring the wave durations is depicted in the timing diagram shown in ~IG.
12.
The RECEIVER ~0 thus automatically interprets the interval-coded waves, identifies and outputs the message conveyed, and stores the messages for possible subsequent use.
Message Storage/Retrieval System Referring to FIG. 13 there is depicted a novel Message Storage/Retrieval system 90 which may operate at equal or differing speeds during storage and subse~uent retrieval, i.e.
one novel feature of the invented System is that its principle of operation is lndependent of the operating speeds.
The System 90 is realized by inserting between the Transmitter 21 and the Receiver 60, a wave-transition record/playback unit such as a magnetic or optical recorder 91.
No modification is required on the Transmitter and Receiver in spite of the fact that with differing record and playback speeds the waves first recorded and the waves subsequently retrieved are in different time scales. Such operation is possible because the messages are interval coded and hence, NOT frequency specific.
A possible wave-transition record/playback unit for use in the system 90 can be realized with a commercially available tape deck and additional hardware as shown in FIG. 14. For example, a TEAC (trade mark) A-4300 with open-reel tape Maxell (trade mark) XLI 35-9OB is used with its recording le~el adjusted such that its monitor line output is about 0.6 volts peak-to-peak.
Its playback level is adjusted to give a signal of about 2 volts peak-to-peak at circuit point Y.
The Interval-coded waves from the Transmitter 21 are fed to the input LINE IN of the tape deck 91 and recorded at speed 1 (e.g. at 7.5 ips~. Upon playback at speed 2 (which may be different to speed l, e.g. at 3.25 ips) the interval-coded wave first recorded is retrieved and output at LINE OUT of the tape deck operating at playback mode 92. The signal is fed to a buffer, through a capacitor 94 and resistor 96 to the inverting input of an operational amplifier 98 which has a non-inverting input biased to +6V, i.e. 1/2 Vcc. A portion of the output of ~ 3 ~

operational amplifi~r 98 is fed through a resistor loo to chassis ground and throu~h resistor 102 back to its inverting input. The other portion of the output is fed to a differentiator, through a resistor 104 and capacitor 106 to the inverting input of an operational amplifier 108 which has a non-inverting input biased to +6V and a portion of its ou~put is fed through resistor 110 to chassis ground and through resistor 112 back to its inverting input. The other portion of the output of the operational amplifier 108 is fed through circuit point Y and capacitor 114 to a Schmitt trigger 116. The Schmitt trigger 116 consists of a MC1455 TIMER with its R and V+ points connected to ~5V, its GND
to chassis ground, and its input points TH and TR tied together at the mid-point of a potential divider formed with equal resistors 118 and 120 across +5V and chassis ground. The interval-coded output ~aves from the Schmitt trigger 116 are fed to the ~eceiver 60.
The system of the present invention is quite versatile and n~ay be employed in different manners. One such manner would be to use a set of interval-coded durations differing by equal duration increments. (For example using a set of interval-coded durations such as ... 2494, 2497, 2500, 2503, ... etc. wherein the duration increment is 3 as practised in a following concrete example.) In this manner of MI coding it should be noted that if the least duration in the set is predetermined and the magnitude of the equal duration increment also predetermined then there is a preferred number of interval-coded durations for the set, i.e.
a preferred coding for speed~ transmissions of random information as indicated in TABLE III.
TABLE III
~0 (EOUAL DURATION INCREMENT~ PREFERRED NUMBER
(LEAST SURATION OF SET) OF STATES FOR
CODING
==___ =__===========_======================__=======
0.2 8 0.025 32 0.0098 64 ~0 0.00404 128 0.00172 256 __________________________________________________________ r 3 o. 15 lo t t ---e c. e c.
TABLE III shows specifically the preferred MI coding, respectively, for each of several cases where the ratio of (equal duration increment)/(least duration of the set) is predetermined.
And the preferred number of interval-coded durations for each case is found to be 8, 16, 32, 64, 128, 256 and 10, respectively.
The use of TABLE III i5 further explained with the following example: Say, if the least duration and magnitude of duration increment for such coding are chosen to be 100 and 20, respectively, then, from TABLB III, 8-state (1 of-8 message) coding is the preferred coding and in this case the set of interval-coded durations should be 100, 120, 140, 160, 180, 200, 220, and 240.
As a concrete example of this system, using 256-interval coding, it can be achieved by coupling the specific transmitter 21 to the specific receiver 60 described above through a suitable transmission media, with the transmitter 21 programmed with the program hereafter listed:
Transmitter Proqram II
REM INVENTED BY HO KIT-FUN
REM UNPUBLISHED COPYRIGHT
REM
REM P.O. Box 54504 REM NORTH POINT
REM HONG KONG
REM

REM
?~FE6B=~CO : REM SET USER 6522 AT FREE-RUNNING MODE
92 ?&FE62=&80 : REM INITIALIZE OUTPUT (SET PB7 AT HIGH) 94 ?&FE6E=&OO : REM INTERRUPT DISA~LED

120 DR%=2509 : REM SET REFERENCE "HALF-CYCLE"
DURATION, PROGRAMMABLE
125 DD%=3 : REM DURATION INCREMENT
130 DELAY%=2 140 DSL%=&4000: "DSH%=&5000 : REM LOCATION OF MI TABLE
145 DIM LOCATION%(255) 150 FOR M = 0 TO 255 : REM THE MESSAGE IS ANY INTEGER

180 REM (EACH MESSAGE HAS THE SAME INFORMATION CONTENT
AS 8 BINARY BITS) 3 j 200 DS%=DR%-M*DD% : REM COMPUTE SIGNAL "HALF-CYCLE"
DURATION
230 DS%=DS%-DELAY% : RF.M DELAY CORRECTION
232 REM TRUE DURATION = PROGRAMMED DURATION + DELAY
235 DSH%?M=DS% DIV 256 238 DSL%?M=DS% MOD 256 245 REM: FOR A SPECIFIC RANDOMLY ASSIGNED MI TABLE
250 DATA 21,36,51,1 231,198,40,125 2,111,159,10, 68,220,232,5 251 DATA 61,123,222,249 46,19,92,151, 188,215,3,4, 56,101,223l175 252 DATA 77,8,25,26, 97,132,255,69, 105,143,211,6, ~0,228,196,203 253 DATA 83,49,126,119, 246,9,43,117, 208,29,30,224, 138,139,13,17 254 DATA 157,182,201,127, 52,33,147,113, 55,28,115,187, 194,243,64,22 255 DATA 59,226,238,200, 87,190,41,15, 66,72,229,240, 253,75,31,23 256 DATA 122,18,45,62, 191,205,24,221, 44,245,109,93, 42,14,186,227 257 DATA 155,154,153,39, 11,71,76,104, 95,100,169,207, 216,14~,131,120 258 DATA 150,140,130,160, 168,212,233,244, 177,166,48,73, 96,112,165,172 259 DATA 133,170,219,242, 27,53,78,108, 136,145,146,213, 236,250,#99,50 260 DATA 184,185,148,60, 16,80,82,98, 178,209,210,241, 152,54,57,114 261 DATA 110,70,32,86, 89,135,197,247, 206,116,65,67, 74,141,204,239 262 DATA 252,156,174,134, 84,88,158,230, 202,149,161,217, 91,94,103,118 263 OATA 128,99,106,102, 225,171,163,167, 192,193,189,181, 179,195,176,0 264 DATA 137,237,107,38, 164,235,183,20, 58,173,218,251, 35,63,124,162 265 DATA 214,79,37,142, 180,81,12,129, 234,248,254,34, 47,85,7,121 268 LOCATION%=&3800 270 FOR MESSAGE% = 0 TO 255 275 LOCATION%?(MESSAGE%) = M

300 N=128 : REM TAKE N INPUT MESSAGE UNITS
(N =1,11,128 ETC., PROGRAMMABLE) 320 DTA~=&3000 : ?DTA%=N
330 FOR NUM% = N TO 1 STEP -1 340 INPUT MESSAGE% :REM e.g. CONFIDENTIAL DIGITAL DATA
350 DTA%~(NUM%)=LOCATION%?(MESSAGE%) (Lines 390 tO 770 same as in Transmitter Program I above) The receiver 60 of FIGS. 9 and 11 may be employed with Microcomputer 66, programmed ~ith the ~ollowing program.
Receiv r Proqram II
50U0 REM INVENTED BY ~I0 KIT-FUN

5004 REM P.O. BOX 54504 5050 N=128 : REM NUMBER OF SIGNALS
5060 n=N+l : REM NUMBER OF WAVES
5070 CONSTANT1%=128*256 5080 DIM Ibound(256),DSB(257),CTIME%(n), DURATION%(N), STORAGE%(N),M(256),LocATION%(2s6) 5090 HTIME=&5500 5100 LTIME=HTIME+n+l 5105 STORAGE%=&4000 : REM STORAGAE LOCATION
5107 REM INTERVAL BOUNDARIES AS PER TRANSMITTER MI TABLE, i.e. "DSB=DR%-(m-0.5)*DD%" AND "Ibound(M)=DR%/DSBI' 5108 FOR m=O TO 256:Ibound(m)=2509/(2509-(m-0.5)*3):
NEXT:REM INTERVAL BOUNDIES
(Lines 5110 to 5555 same as Rec~iver Program I, above) 5560 FOR m=O TO 256:DSB(m)=DURATION%(O)/Ibound(m):NEXT

30 5600 DATA 223, 3, 8, 26, 27, 15, 43, 254 33, 53, 11, 1~6 246, 62, 109, 87 5610 DATA 164, 63, 97, 21, 231, 0, 79, 95, 102, 34, 35, 148 73, 57, 58, 94 5620 DATA 178, 69, 251, 236, 1, 242, 227, 115, 6, 86, 108, 54, 104, 98, 20, 252 5630 DATA 138, 49, 159, 2, 68, 149, 173, 72, 28, 174, 232, 80, 163, 16, 99, 237 5640 DATA 78, 186, 88, 187, 12, 39, 177/ 117, 89, 139, 188, 93, 118, 32, 150, 241 40 5650 DATA 165, 245, 166, 48, lg6, 253, 179, 84, 197, 180, 44, 204, 22, 107, 205, 120 5660 DATA 140, 36, 167, 209, 121, 29, 211, 206, 119, 40, 210, 226, 151, 106, 176, 9 5670 DATA 141, 71, 175, 74, 180, 55, 207, 51, 127, 255, g6, 17, 238, 7, 50, 67 5680 DATA 208, 247, 130, 126, 37, 144, 195, 181, 152, 224, 60, 61, 129, 189, 2~3, 41 5690 DATA 125, 153, 154, 70, 162, 201, 128, 23, 172, 114, 113, 112, 193, 64, 198, 10 50 5700 DATA 131, 202, 239, 214, 228, 142, 137, 215, 132, 122, 1~5, 213 143, 233, 194, 31 5710 DATA 222, 136, 168, 220, 244, 219, 65, 230, 160, 161, 110, 75, 24, 218, 85, 100 5720 DATA 216, 217, 76, 221, 46, 182, 5, 158, 83, 66, 200, 47, 190, 101, 184, 123 5730 DATA 56, 169, 170, 42, 133, 155, 240, 25, ~3~3~

124, 203, 23~, 146 13, 103, 18, 30 5740 DATA 59, 212, 81, 111, 45, so, 199, 4, 14, 134, 248, 229 156, 225, 82, 191 5750 DATA 91, 171, 147, 77, 135, 105, 52, 183, 249, 19, 157, 235, 192, 92, 250, 38 5800 LOCATION%=&6000 5820 FOR M=O TO 255 5840 READ MESSAGE%
5860 LOCATION%?M=MESSAGE%

6000 FOR Y=l TO N
6010 IF DURATION%(Y) DSB(O) THEN PRINT "ERROR IN
MESSAGE (";Y;")": M(Y)=127: GOTO 8000 6020 m=l 6030 IF DURATION%(Y) > DSB(m) THEN M(Y)=m-l : GOTO 8000 6040 m=m+l 6045 IF m=257 THEN PRINT "ERROR IN MESSAGE (";Y"')" :
M(Y)=255: GOTO 8000 8000 STORAGE%?Y =LOCATION%?M(Y) 8100 PRINT "MESSAGE (";Y;") = ";STORAGE%?Y :REM DISPLAY
CONFIDENTIAL DATA

With the system so constituted a 256-state MI Table is provided in the system. An example of such a table is as follows:
TABLE IV
MESSAGE DR DS
UNIT
_________________________________________ _____ _______________ 50 _ ______________________ (256 randomly-paired MI coding) Wherein each of the 256 message units may be arbitrarily ~ ~?~ 3 assigned letters and numbers or other digital data. When many-state, such as this 256-state MI coding is used the system is especially suitable for data transmission, confidential data in particular. Using a random order in the M~ coding, such as that shown in TAB~E I~' would add a layer of complexity, making it difficult to break as a code.
At the Transmitter 21 each confidential 256-state message is transformed into an interval-coded wavelet (that means 1 byte of information at a time) according to the secret MI Table, which contains a set of 256 message units each of which has been randomly and uniquely assigned to 1 of 256 interval-coded durations.
At the Receiver 60 such waves are detected and decoded into the original confidential messages 1 byte at a time in accordance with the same secret 256-state MI coding.
It is not practical to guess at the secret MI coding if such coding is not provided since the number of permutations in this case involves 256 factorial and the secret MI coding can be changed from time to time. ~ence, such interval~coded waves, even if intercepted at the path between the Transmitter 21 and the Receiver 60 do not easily reveal the messages being conveyed.
By inserting more reference waves into the signal wave stream the Interval-coded-wave System can tolerate greater frequency drifts/shifts. And in the extreme we may choose to transmit a reference wave next to each signal wave such as follows: WR(1) ~ WS(1) ~ WR(2) ~ WR(N) t WS(N) ~ which means that the reference may be changed and up-dated for every single message unit for subsequent interval evaluation. Such format permits frequency hopping between message units, wherein the intervals may be respectively defined by the waves WR(1) and WS(1)~ WR(2) and ~S(2), . , WR(N) and WS(N), etc.
Furthermore, the process and transmitter of the present in~ention may be practiced and implemented in another manner to transmit information in the form of interval-coded tones such as interval-coded musical tones (i.e., tones belonging to a musical scale) which are capable of being easily recognized by a human listener who may then identify the information encoded therein.

- ~. 3 ~ ~.,J~

Again, this manner of information transmission is implemented with the MI table of FIG. 4, the process of FIG. 5 and the transmitter of FIG. 6. The transmitted toners are multicycle waveforms. There are shown some suitable waveforms in FIG. 1.
As a concrete example, let us assume that we wish to transmit numerical values. WP could then make up a MI table with suitable musical intervals such as this:
TABLE V
Message Interval Reference Signal Unit Tone Tone Frequency Frequency (Hz) (Hz) ________________________________ _________________________ - 0.7500 512 384 . 0.8333 512 463 0 0.9375 512 480 1 1.000 512 512 2 1.125 512 576 3 1.250 512 6~0 4 1.333 512 682 1.500 512 768 6 1.667 512 85~
7 1.875 512 960 8 2.000 512 1024 9 2.250 512 1152 etc.
FIG. 5 again shows the steps in practicing the process of the present invention. From a start at 12 the first step 14 is to establish the MI Table such as MI Table V (step 14). The next step 16 is to input specific message units M(l~...M(N) (for example, the message units "-", "1", "5", and "2", using Table V shown above) at step 16 and select the corresponding intervals from the MI Table of step 14. The final step 18 is to generate and transmit tones WR~ WS(1) ~ etc. (e.g., the tone series l'512-HZ
tone (reference tone), 384-Hz tone (data tone), 512-Hz tone (data tone), 768-Hz tone (data tone), and 576-Hz tone (data tone~") in accordance with the input of step 16 and when this is done the operation is over at step 20. The currently preferred protocol output sequence is that the reference tone is transmitted first followed by the series of information tones. The series of tones so generated are wseful as they carry interval-coded information and include a reference with which the information may be decoded, whereby information transmission may be achieved. The transmitted ted tones may be interpreted by a human listener.
(Of course, the information carried by these tones may also be automatically decoded by an above-mentioned Receiver programmed to operate with multi-cycle waves.) It should be noted that a significant advantage of implementing the present invention in this manner is that the tonal differences of such transmitted musical tones may be distinguished by a human listener more reliably than other tones bearing nonmusical intervals. A human listener who is skillful in recognizing the tones of a musical scale may recognize these output tones as tones belonging to a musical scale (interval-coded tones). (Even children would find it easy to recognize a simple musical tone series such as, say, "DO-ME-SO" and distinguish it from, say, "DO-MB-LA".) On hearing the transmitted tone series the listener may subjectively regard the first tone in the series as a reference "DO" of a certain musical scale and hence recognize the transmitted tone series as specific tones on that scale due to their interval relationship (e.g., recognizing them as the relative tone series:
"DO" "SO," "DO" "SO" "RE" ).
If the MI Table is known and the first tone in the series is also known t~ be a reference, the listener may therefore interpret the specific information tones in the transmitted tone series as "-", "1", "5", and "~". The system of the present invention provides a tone output method and transmitter operable as an output means in a specific device or system, and may serve as an alternative to visual displays.
Although the specific intervals used in TABLE V 30 belong to a natural (diatonic) scale, corresponding intervals belonging to a slightly different scale such as the equally-tempered scale can also be used satisfactorily.
It should be further noted that one of the advantages of the present system is that its principle of operation isnon-frequency specific. A transposed frequency set at another pitch can just as well be adopted in TABLE V to generate tones at a higher or lower pitch without departing from the specific intervals contained therein. This makes numerous similar frequency sets ~ 3 ~
compatible and hence permits greater freedom in the design of system hardware, and makes transmitters at different frequency ranges compatible.
The Transmitter 21 of FIGS. 5 and 6 is employed to carry out the above process. As a specific e~ample of a dedicated version for carrying out the above process for tones (multi-cycle waves) the transmitter has been constructed using a microcomputer 22, a MI Table 26 having its set of different message units respectively associated to different musical intervals, i.e., intervals belonging to a musical scale, such as those intervals shown in TABLE V above, and a programmable sound generator (e.g., a sound processor chip connected with loudspeaker output3 as gen-erator 30 to transmit audible tones as output waves at 32 in the form of multi-cycle waves such as those waveforms shown in FIG.
1~ Specific message units from a source such as a keyboard, a memory location or other circuits are sequentially fed to the transmitter at 24.
As another concrete example of the process or system of the present invention, the transmitter is employed to embody a clock 130 shown in FIG. 15 which measures time and which outputs the component digits of the value of time by transmitting interval-coded musical tones 132. These tones "tell" time, and may serve as an alternative to visual displays. This clock is embodied by coupling a timer 135 for measuring time with digital output to and at the front end of the above transmitter 21. This clock has been constructed and successfully operated using the internal timer of the BBC Microcomputer Model B as timer 135, and the same Nicrocomputer as microcomputer 22, and the standard sound chip (a SN76489 chip) which is already connected with loudspeaker output in same Microcomputer as programmable wave generator 30, and TABLE V as MI Table 26 set up in the R~ of same Microcomputer. A suitable program for the microcomputer 22 of this embodiment is listed below as Transmitter Program III:
Transmitter Proaram III

100 PITCHR-lOl ~ 3 ~ ~ A~

120 PITCHl=PITCHR
140 PITCH2=PITCHR+8 150 PITCH3=PITCHR+16 160 PITCH4=PITCHR+20 180 PITCH5=PITC}IR+28 200 PITCH6=PITCHR+36 220 PITCH7=PITCHR+44 240 PITCH8=PITCHR+48 260 PITCH9=PITCHR+56 280 PITCHlO=PITCHR--4 300 PITCHll=PITCHR-12 320 PITCH12=PITCHR-20 510 INPUT''HOUR'I,HOUR
520 INPUT"MINUTE",MINUTE
530 RESETTIME=(60*HOUR+MINUTE)*6000 550 TIME=RESETTIME
600 DIM NOW~6) 610 CHANNEI.=l 615 VOLUME=-12 620 DURATION=lO
625 PAUSE%=lOOO
700 AI~RMMODE = O
800 KEY=INKEY(lOO) 810 IF KEY=32 THEN GOSUB 1040:
REM PRESS "SPACE BAR" FOR TIME TONES
820 IF KEY=65 THEN GOSUB 3500:
REM PRESS "A" TO SET ALARM
830 IF ALARM~IODE = 1 THEN GOSUB 3800 1042 SOUND CHANNEL,VOLUME,PITCHR,DURATION
1045 FOR PAUSE=l TO PAUSE%:NEXT
1050 NOW=TIME: REM READ INTERNAL TIMER
1100 NOW (0)=60 1150 NOW (4)=((NOW DIV 6000)MOD 60)MOD 10 1200 NOW(3)=((NOW DIV 6000)MOD 60)DIV 10 1250 NOW(l)=((NOW DIV 360000)MOD 24)DIV 10 1300 NOW(2) ((NOW DIV 360000)MOD 24)MOD 10 1390 N=O
1400 N=N+l 1420 PRINT N, NOW(N) 1450 IF N=l AND NOW(N)=O THEN GOTO 1400 1460 IF N=3 THEN GOTO 3000 1470 IF N=3 AND NOW(N)=O THEN GOTO 1400 1500 ON NOW(N)+l GOSUB 2000,2010,2020,2030,2040, 2050,2060,2070,2080,2090: REM MI TABLE
1600 SOUND CHANNEL,VOLUME,PITCH,DURATION
1650 FOR PAUSE=l TO PAUSE%:NEXT
1700 IF N<4THEN GOTO 1400 2000 PITCH=PITCHlO

2010 PITCH=PITCHl 3 .~

2020 PITCH=PITCH2 2025 RErrURN
2030 PITCH=PIT~H3 2040 PITCH=PITCH4 2050 PITCH=PITCH5 2060 PITCH=PITCH6 2070 PITCH=PITC~7 2080 PITCH=PITCH8 3000 FOR PAUSE=l TO PAUSE%:NEXT
3010 SOUND C~ANNEL,VOLUME,PITCHR,DURATION
3015 FOR PAUSE=l TO PAUSE%:NEXT

3205 ALARMMOD~=O

3215 QUIET=O

3230 FOR PAUSE=l TO 3*PAUSE% : NEXT
3250 QUIET=INKEY(lOO) 3260 UNTIL QUIET=32 :
REM PRESS "SPACE BAR" TO STOP ALARM

3520 INPUT "HOUR", ALARMHOUR
3530 INPUT "MINUTE", ALARMMINUTE
3540 ALARMTIME =60 * ALARMHOUR + ALARMMINUTE
3550 ALARMMOOE = 1 380~ REM TESTTIME
3810 IF INT (TIME/6000) = AL~RMTIME THEN GOSUB 3200 In operation the timer 135 keeps the running time. Upon a pre-programmed condition the microcomputer 22 reads the value of the running time from timer 135 and converts it into hour and minute component digits. Then the transmitter 21 takes these specific component digits as message units and responds by transmitting two interval-coded tone series respectively in a specific protocol output sequence representing the component digits of the value of the running time. This sequence of operations is carried out with the above Transmitter Program III.
In this current embodiment of the clock 130, depressiny a key (on J L ~
microcomputer 22) causes the clock to output the current value oî running tim~ by transmitting a first tone series representing the hour component decimal digits and a second tone series representing the minu~e component decimal digits of the time.
That is, th~ clock "tells" time by transmitting firstly the "hour" tones followed by the "minute" tones. For simplicity, it is currently preferred that the most significant component digit be supressed if it is a zero. The exact manner of time output in this embodiment is further demonstrated with the following 10 examples: the time, say, 02:35 is transmitted as the tone series "512-Hz tone (reference), 576-~z tone (least significant hour digit)" followed by the tone series "512-~z tone (reference), 640-Hz tone (most significant minute digit), 768-Hz tone (least significant minute digit)", whereas the time, say, 10:05 is transmitted as the tone series "512-Hz tone (reference), 512-Hz tone (most significant hour digit), 480-Hz tone (least significant hour digit)" followed by the tone series "512-Hz tone (reference), 768-Hz tone (least significant minute digit)".
This embodiment of the clock therefore enables a human 20 listener to "hear" the time.
The transmitter of the present invention is also employed in a monitor system to provide a novel alarm feature, ~h~rein an alarm condition has been preset and if the same condition is matched the transmitter automatically (and repeatedly if so preferred) transmits the tone series representing the component digits of the current value of a variable being monitored, whereby the transmitted tones may accomplish two purposes, i.e.
providing alarm tones while at the same time conveying the updated value of a monitored variable.
Such alarm feature is already successfully embodied in the clock described above, using the same Transmitter Program III
above, wherein the time for alarm may be preset and upon reaching the same time the clock automatically transmits alarm tones in the form of the above tone series (of clock 130) representing the component digits of the updated time value. Such alarm tones are more informative than conventional alarm tones, as they serve as an alarm while at the same time they convey the current component ~ 3 ~

digits of the running time.
Of course, if preferred th~ above~mentioned clock may be embodied in the form of a digital watch equipped with sound output.
As yet another concrete example to show that the method and system of the transmitter may be employed as an output means in specific devices and instruments, etc., a measuring device 140 is shown in FIG. 16. The device 140 measures a specific analog quantity at input 142 and outputs the component digits of the measured value by transmitting interval-coded musical tones 144, and it is realized b~ coupling an analog-to-digital converter 146 to and at the front end of transmitter 21. In the following speci~ic example described, the devics measures a D.C. voltage (which may be the electrical analog of yet another specific quantity) of magnitude between 0 V and 1.80 V. The device has been constructed and successfully operated by coupling a PD7002 (A/D converter chip) which is already provided in the BBC
Microcomputer Model B to the transmitter 21 embodied with the same Microcomputer. In operation the quantity to be measured, in this case a D.C. voltage is input at an analog input channel (e.g., channel 2) of the PD7002 chip. The microcomputer 22 of the transmitter 21 has been additionally programmed to read the corresponding digital output value from the PD7002 and convert this output value into component decimal digits which are subsequently taken as the specific message units. Then the microcomputer 22 of the transmitter 21 operates in the same general manner as described in the earlier embodiments; the transmitter 21 takes the above specific component message units, and subsequently converts and transmits them as interval-coded tones at output 32. A suitable program for the microcomputer 22 to accomplish the operations described is listed as Transmitter Program IV as follows:
Transmitter Program IV

100 PITCHR=lOl 120 PITCHl=PITCHR
140 PITCH2=PITCHR+8 ~3~3 .~ ~3'~3 150 PITCH3=P:[TCHR+16 160 PITCH4=PITCHR-~20 180 PITCH5=PITCHR+28 200 PITCH6=PITCHR~36 220 PITCH7=PITCHR~44 240 PITCH8=PI~CHR+48 260 PITCH9=PITCHR+56 280 PITCHlO=PITCHR-4 300 PITCHll=PITCHR-12 320 PITCH12=PITCHR-20 610 CHANNEL=l 615 VOLUME=-12 620 DURATION=lO
625 PAUSE%=lOOO
690 KEY=GET
700 REM 0 <= VOLTAGE <= 1.8 705 VOLTAGE = 1.8*ADVAL(1)/65520 : REM MEASURE VOLTAGE
710 VO = INT VOLTAGE
720 Vl = INT (VOLTAGE*lO)MOD 10 730 V2 = INT (VOLTAGE*lOO)MOD 10 1042 SOUND CHANNEL,VOLUME,PITCHR,DURATION
1045 FOR PAUSE=l TO PAUSE%:NEXT
1490 PRINT VO:

1500 ON VO+l GOSUB 2000,2010,2020,2030,2040,2050, 2060,2070,2080,2090 1518 PRINT ".";
1520 PITCH=PITCHll:GOSUB 1600:REM DECIMAL POINT
1528 PRINT Vl;
1530 On Vl+l GOSUB 2000,2010,2020,2030,2040,2050, 2060,2070,2080,2090 1550 On V2~1 GOSUB 2000,2010,2020,2030,2040,2050, 2060,2070,2080,2090 1600 SOUND CHANNEL,VOLUME,PITCH,DURATION
1650 FOR PAUSE=l TO PAUSE%:NEXT

2000 PITCH=PITCHlO

2010 PITCH=PITCHl 2020 PITCH=PITCH2 2030 PITCH=PITCH3 2040 PITCH=PITCH4 2050 PITCH=PITCH5 2060 PITCH=PITCH6 ~3~9~

2070 PITCH=PITCH7 2080 PITC~=PITCH8 2090 PITCH=PITCH9 In this specific example, the device 140 functions as a digital voltmeter. When a voltage of, say, 1.50 V is measured the device converts the measured value into a i ~ series of specific message units, in this case into "1", ".", "5", "0" and, in the general manner described earlier and in accordance with TABLE V, transmits a corresponding interval-coded tone series, in this case the following tone series: "~12-Hz tone (reference), 512-Hz tone (data), 463-~z tone (data), 768-Hz (data), 480-~z (data)". It is understood that other ~/D converters, voltage dividers, etc. may be employed in the device for measuring other voltage ranges.
From the several embodiments described, it is clear 20 that the tone output method and the transmitter of the present invention may be practiced and employed in various systems and devices, such as digital multimeter, thermometer, pressure meter, etc., and may serve as an alternative output means to visual displays. And in various such embodiments the output protocol can be changed if preferred, such as by using the last tone in the transmitted tone series to code the exponent of the value of the quantity being expressed. For example, still using TABLE V, a value of say "350000" is expressed and transmitted as the following tone series: "512-Hz tone (reference), 640-Hz tone (data), 768-Hz tone (data), 682-Hz tone ~data) 1I to convey "3" and "5" followed by four zeros.
From the foregoing description, it will be apparent that the system of the present invention provides a method and system for communication which has advantages over the prior art.
While several embodiments of the system of the invention have been shown and described, changes and modifications may be made to the system without departing from the teachings of the invention and, ther~fore, the invention is only to be limited as ~ 3 ~
necessitated by th~ accompanying claims.

Claims (80)

1. A process for transmitting information consisting of a series of message units selected from a set of defined message units, said transmission process comprising the steps of:
(a) defining the message units comprising the set of defined message units;
(b) assigning a message unit ratio to each defined message unit;
(c) providing a periodic reference signal having a reference periodic property;
(d) converting each message unit of the information to be transmitted into a set of signals including said reference signal, each message unit being a member of the set of defined message units and related to said reference signal by a specific message unit ratio;
(e) providing an information signal having an information periodic property, said information periodic property being varied for each message unit to conform to the message unit ratio for each message unit;
(f) transmitting said periodic reference signal and said information signal;
(g) receiving said periodic reference signal and said information signal;
(h) determining a received message unit ratio between said reference periodic property and said information periodic property of the received signals:
(i) deconverting said received message unit ratio to a message unit in accordance with the assigned message unit ratio, thereby to convey the information.

2. The process of claim 1 including the steps of: utilizing a first station and a second station; providing and transmitting from said first station a first periodic reference signal and a first information signal; providing and transmitting from said second station a second periodic reference signal and a second information signal; said first period reference signal and said second periodic reference signal differing in fundamental frequencies but said steps of defining and assigning of claim 1 being identical in each station.

3. The process of claim 1 wherein said periodic reference signal is transmitted first followed by said information signal.

4. The process of claim 1 wherein said information periodic property is transmitted for one half of the duty cycle of the information signal established by each message unit.

5. The process of claim 1 wherein the period of the periodic reference signal is changed after the information signal has been transmitted with the varied information periodic property for a message unit.

6. The process of claim 1 wherein said periodic reference signal is audible and said information signal is audible.

7. The process of claim 3 wherein said periodic reference signal and said information signal are audible.

8. The process of claim 6 wherein said message unit ratios include ratios which result in said information signal being varied for a message unit in a manner that the information signal is cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

9. The process of claim 6 including the step of assigning the set of defined message units, message unit ratios which are associated with message tone frequencies, including ratios of 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875 and 2.000.

10. The process of claim 5 wherein said reference signal and said information signal are audible.

11. A signal transmitter for transmitting a message comprising a series of specific message units taken from a set of possible message units, such as an alphabet, said transmitter comprising:
(a) table means defining each member of the set of possible message units as a ratio relationship;
(b) means coupled to the table means for receiving the series of specific message units, and for sequentially determining the ratio relationship defined for each successive specific message unit of the message;

(c) means coupled to said receiving and determining means for generating electrical signals including a periodic reference signal having a reference periodic property and for generating an information signal having an information periodic property, said information periodic property being varied for each message unit, the information periodic property being related to the reference periodic property by the ratio relationship determined by said determining means, and (d) output means for coupling said generated signals to transmission means, such as a transmission line or a broadcast radio transmitter or an optical fiber.

12. The transmitter of claim 11 including means for transmitting said periodic reference signal first followed by said information signal.

13. The transmitter of claim 11 including means for transmitting said information periodic property for one half of the duty cycle of the information signal established by each message unit.

14. The transmitter of claim 11 including means for transmitting the series of information signals by sequentially transmitting a single half word.

15. The transmitter of claim 11 including means for changing the period of the periodic reference signal after the information signal has been transmitted with the varied information periodic property for a message unit.

16. A signal receiver for receiving and decoding electrical signals comprising:
(a) an input unit for receiving electrical signals, including a reference signal and an information signal, each having a periodic property, and for determining the periodic property of received information and reference signals;
(b) table means for defining each member of a set of possible message units, such as an alphabet, as different specific ratio relationships between an information periodic property of the information signal and a reference periodic property of the reference signal;
(c) means intercoupled with said table means and said input unit for computing the ratio relationship between the information periodic property and the reference periodic property for producing a series of message units from said table means in response to the computed ratio relationships determined from the received signals;
(d) output means coupled to said intercoupled means for reproducing the series of message units defined by said last named means.

17. The receiver of claim 16 including means for receiving said reference signal first followed by said information signal.

18. The receiver of claim 16 wherein said table means includes means for defining a message unit for a continuous range of ratios between certain specific values.

19. The receiver of claim 16 including means for sequentially receiving a variety of reference signals having distinguishable periodic properties.

20. A tone transmitter for transmitting information comprising a series of specific message units taken from a set of possible message units, such as an alphanumeric set, said transmitter comprising:
(a) means for assigning each member of the set of possible message units a message tone at a frequency representative of a specific tone frequency ratio to a reference tone frequency to form the series of specific message units;
(b) means for receiving the series of specific message units;
(c) means coupled to said assigning means and said receiving means for sequentially transmitting the reference tone at the reference tone frequency and the assigned message tone for each of said specific message units.

21. The tone transmitter of claim 20 including means for transmitting the reference tone frequency first followed by the series of message tones.

22. The tone transmitter of claim 20 wherein the specific tone frequency ratios include ratios which result in the assigned message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

23. The tone transmitter of claim 20 including means for assigning the set of possible message units, message tones, respectively, including those tones of frequencies representative of specific tone frequency ratios 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

24. The tone transmitter of claim 20 including means for changing the reference tone frequency following the transmission of a message tone.

25. A tone output device in a digital measuring system for measuring a specific quantity, comprising:
(a) means for generating audible tones;
(b) means for receiving component digits of a measured value of said specific quantity; and (c) control means coupled to said generating means and to said receiving means for sequentially generating and transmitting a reference frequency tone and, for each of said received component digits, a message tone at a specific frequency ratio to the frequency of said reference frequency tone, said specific frequency ratio being invariant for a given component digit.

26. The tone output device of claim 25 further including table means for assigning specific frequency ratios for the message tones.

27. The tone output device of claim 25 including means for transmitting the reference frequency tone first followed by a series of message tones.

28. The tone output device of claim 25 wherein the specific frequency ratios include ratios which result in the specific message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

29. The tone output device of claim 25 including means for assigning to a set of digits, message tones, respectively, including those tones of frequencies representative of specific frequency ratios 1.00, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

30. A clock with tone output means, comprising:

(a) means for measuring time represented by component digits;
(b) means coupled to said measuring means for converting each of said component digits into a message tone at a specific frequency ratio reference frequency tone, said specific frequency ratio being invariant for a component digit;
(c) means coupled to said converting means for relating and transmitting said message tone and said reference frequency tone in sequential order in a tone series, whereby the time value may be transmitted.

31. The clock of claim 30 including means for transmitting the reference frequency tone first followed by a series of message tones.

32. The clock of claim 30 wherein the specific frequency ratios include several specific frequency ratios which result in a specific message tone which is cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

33. The clock of claim 30 wherein the specific frequency ratios include tone frequency ratios 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

34. The clock of claim 30 including means for detecting a predetermined condition, such as a depressed key or passing of the time for alarm, and for causing the clock automatically to transmit an alarm tone series including the reference frequency tone and the message tones for the specific component digits of the time.

35. An analog voltage measuring device for representing a measured voltage, comprising:
(a) first means for converting an analog voltage to representative component digits;
(b) second means coupled to said first converting means for converting each of said component digits into a message tone at a specific tone frequency ratio to a reference frequency tone, said specific tone frequency ratio being invariant for a component digit; and (c) means coupled to said second converting means for elating and transmitting said message tones and said reference frequency tone in sequential order in a tone series, whereby the measured voltage may be transmitted.

36. The measuring device of claim 35 including means for transmitting the reference frequency tone first followed by the series of message tones.

37. The measuring device of claim 35 wherein the specific tone frequency ratios include ratios which result in a message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

38. The measuring device of claim 35 wherein the specific tone frequency ratios include 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

39. A process of information transmission, wherein the information consists of a series of specific message units out of a set of possible message units each of which is associated with a message tone frequency at a specific interval referred to as a reference tone frequency, comprising the steps of:
(a) inputting said series of specific message units;
(b) generating in response to each of said input message units a message tone at a frequency at the specific interval associated with the same message unit; and (c) relating and transmitting said generated message tone in sequential order in a tone series including said reference tone, whereby information transmission may be achieved.

40. The process of claim 39 wherein the reference tone is transmitted first followed by the series of message tones.

41. The process of claim 39 wherein the specific intervals belong to the specific intervals of a musical scale, such as a diatonic scale or an equally tempered scale, operable with tolerance.

42. The process of claim 39 wherein the set of possible message units is assigned message tones respectively including those tones at intervals 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000 referred to the reference tone frequency, operable with tolerance.

43. A process of information transmission, wherein the information consists of a series of specific message units out of a set of possible message units, comprising the steps of:
(a) defining a periodic property ratio relationship with reference to a reference periodic property for each of the members of the set of possible message units;
b) converting and transmitting the information series of specific message units into a set of signals including a reference signal and a series of information signals each having a periodic property related to the reference signal's periodic property by the ratio relationship defined for that specific message unit in the preceding step; and c) receiving said signals, and by determining the periodic property ratio relationship between the reference and information signals, converting them to the defined series of specific message units, whereby information transmission may be achieved.

44. The process of claim 43, wherein information is transmitted and received between two stations each of which employs the process of claim 43 using the same definitions but wherein each station transmits using a different reference periodic property.

45. The process of claim 43 wherein the reference signal is transmitted first followed by the series of information signals.

46. The process of claim 43 wherein the series of information signals are transmitted by sequentially transmitting a single wavelet of half a cycle.

47. A signal transmitter for transmitting a message comprising a series of specific message units, said transmitter compromising:
(a) means for generating signals;
(b) means for receiving the series of specific message units; and (c) control means coupled to said generating means and to said receiving means for sequentially generating and transmitting a reference signal having a reference periodic property and, for each of said received message units, an information signal having a periodic property representative of a specific ratio relationship to said reference periodic property, said specific ratio relationship being invariant for a given message unit, whereby the transmitted signals are tolerant of shifts such as Doppler shift.

48. The transmitter of claim 47 wherein the reference frequency signal is transmitted first followed by the series of information signals.

49. The transmitter of claim 47 wherein the signals are respectively single half-cycle signals.

50. The transmitter of claim 47 wherein the series of information signals are transmitted by sequentially transmitting a single half-cycle.

51. A signal receiver for receiving and decoding signals comprising:
(a) an input unit for receiving signals, including a reference signal and an information signal, each having a periodic property, and for determining the periodic property, and for determining the periodic property of received information and reference signals;
(b) means defining each member of a set of possible message units, such as an alphabet, as different specific ratio relationships between an information periodic property of the information signal and reference periodic property of the reference signal;
(c) means inter-coupled with said defining means and said input unit for producing a series of message units in response to the received signals in accordance of said defined ratio relationships.

52. The receiver of claim 51 including means for re-ceiving said reference signal first followed by said information signal.

53. The receiver of claim 51 wherein said defining means includes means for defining a message unit for a continuous range of intervals between certain specific values.

54. The receiver of claim 51 including means for se-quentially receiving a variety of reference signals having distinguishable periodic properties.

55. A process for transmitting information comprising a series of specific message units, said process comprising the steps of:
(a) inputting said series of specific message units;
(b) generating in response to each of said input message units a message tone at a frequency representative of a specific tone frequency ratio to a reference tone frequency, said specific frequency ratio being invariant for a given message unit; and (c) relating and transmitting said generated message tone in sequential order in a tone series including said reference tone, whereby information transmission may be achieved.

56. The process of claim 55 wherein the reference tone is transmitted first followed by the series of message tones.

57. The process of claim 55 wherein the specific tone frequency ratios include ratios which result in the message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

58. The process of claim 55 wherein the specific tone frequency ratios include 1.000, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

59. A tone transmitter for transmitting information comprising a series of specific message units, said transmitter comprising:
(a) means for generating tones;
(b) means for receiving the series of specific message units;
(c) control means coupled to said generating means and to said receiving means for sequentially generating and transmitting a reference frequency tone and, for each of said received message units, a message tone at a specific frequency ratio to the frequency of said reference frequency tone, said specific frequency ratio being invariant for a given message unit.

60. The tone transmitter of claim 59 including means for transmitting the reference frequency tone first followed by the series of message tones.

61. The tone transmitter of claim 59 wherein the specific tone frequency ratios include ratios which result in the transmitted message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

62. The tone transmitter of claim 59 including means for changing the reference tone frequency following the transmission of a message tone.

63. The tone output device in a measuring system for measuring a specific quantity, comprising:
(a) means for generating tones;
(b) means for receiving the component digits of a measured value of a specific quantity; and (c) control means coupled to said generating means and to said receiving means for sequentially generating and transmitting a reference frequency tone and, a said received component digit, a message tone at a specific frequency ratio to the frequency of said reference frequency tone, said specific frequency ratio being invariant for a given component digit.

64. The tone output device of claim 63 further including table means for assigning specific frequency ratios for the message tones.

65. The tone output device of claim 63 including means for transmitting the reference frequency tone first followed by a series of message tones.

66. The tone output device of claim 63 wherein the specific frequency ratios include ratios which result in the specific message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

67. The tone output device of claim 63 including means for assigning to a set of digits, message tones, respectively, including those tones of frequencies representative of specific frequency ratios 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875 and 2.000.

68. A timing device with tone output means, comprising:
(a) means for measuring time represented by component digits;
(b) means coupled to said measuring means for converting each of said component digits into a message tone at a specific frequency ratio to a reference frequency tone, said specific frequency ratio invariant for a component digit;
(c) means coupled to said converting means for relating and transmitting said message tone and said reference frequency tone in sequential order in a tone series, whereby the time value may be transmitted.

69. The device of claim 68 including means for transmitting the reference frequency tone first followed by a series of message tones.

70. The device of claim 68 wherein the specific frequency ratios include several specific frequency ratios which result in a specific message tone which is cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

71. The device of claim 68 wherein the specific frequency ratios include tone frequency ratios 1.000, 1.125, 1.250, 1.333, 1.500, 1.667, 1.875, and 2.000.

72. The device of claim 68 including means for detecting a predetermined condition such as a depressed key or passing of the time for alarm, and for causing the clock automatically to transmit an alarm tone series including the reference frequency tone and the message tones for the specific component digits of the time.

73. An analog measuring device for representing a measured analog quantity, comprising:
(a) first means for converting an analog quantity component to representative component digits;
(b) second means coupled to said first converting means for converting each of said component digits into a message tone at a specific tone frequency ratio to a reference frequency tone, said specific tone frequency ratio being invariant for a component digit; and (c) means coupled to said second converting means for relating and transmitting said message tones and said reference frequency tone in sequential order in a tone series, whereby the measured analog quantity may be transmitted.

74. The measuring device of claim 73 including means for transmitting the reference frequency tone first followed by the series of message tones.

75. The measuring device of claim 73 wherein the specific tone frequency ratios include ratios which result in a message tone being cognizable by a listener as a note of a musical scale, such as a diatonic scale or an equally-tempered scale.

76. The measuring device of claim 73 wherein the specific tone frequency ratios include 1.000, 1,125, 1.333, 1.500, 1.667, 1.875, and 2.000, operable with tolerance.

77. A process for recording information consisting of a series of message units selected from a set of defined message units, said recording process comprising the steps of:
(a) defining the message units comprising the set of defined message units;
(b) assigning a message unit ratio to each defined message unit;
(c) providing a periodic reference signal having a reference periodic property;
(d) converting each message unit of the information to be recorded into a set of signals including said reference signal, each message unit being a member of the set of defined message units and related to said reference signal by a specific message unit ratio;
(e) providing an information signal having an information periodic property, said information periodic property being varied for each message unit to conform to the message unit ratio for each message unit;
(f) recording said periodic reference signal and said information signal;
(g) upon playback receiving said periodic reference signal and said information signal;
(h) determining a received message unit ratio between said reference periodic property and said information periodic property of the received signals; and (i) deconverting said received message unit ratio to a message unit in accordance with the assigned message unit ratio, thereby to retrieve the information.

78. The process of claim 77 wherein said periodic reference signal is recorded first followed by said information signal.

79. The process of claim 77 wherein the period of the periodic reference signal is changed after the information signal has been recorded with the varied information periodic property for a message unit.

80. The process of claim 77 wherein said information periodic property is recorded for one half of the duty cycle of the information signal established by each message unit.