US3870869A

US3870869A - Digital apparatus for the timing and analysis of internal combustion engines

Info

Publication number: US3870869A
Application number: US354849A
Authority: US
Inventors: Arthur Eberle; Nicholas A Spitzer
Original assignee: Columbia Gas Syst
Current assignee: Columbia Gas System Service Corp
Priority date: 1973-04-26
Filing date: 1973-04-26
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A starting impulse generated when the crank shaft of an engine passes a specific point and starts a counter that counts impulses for one revolution. During the same revolution, another signal corresponding to a specific engine event starts another counter that continues until the end of the same revolution. A computing circuit uses data from the counters to determine engine speed and the angle at which the engine event occurs and presents this information as a numerical readout. A mark signal may be generated as a cursor for cathode ray tube display of ignition or other engine waveforms. The cursor can be moved to any point along the waveform by a manual control, and the angle at whatever point is selected will be presented in the numerical readout.

Description

United States Patent [1 1 Eberle et al.

[4 1 Mar. 11, 1975 DIGITAL APPARATUS FOR THE TIMING [54] 3,594.552 7 1971 Adamson 235/92 CV AND ANALYSIS OF INTERNAL COMBUSTION ENGINES Primary Examiner-Gareth D. Shaw Assistant Examiner-Robert F. Gnuse 7 l t A th Eh I 5] nven Ors g z g f g g t gl g Attorney, Agent, or Firm--Curtis, Morris & Stafford of Ohio 1 [73] Assignee: Columbia Gas System Service [57] ABSTRACT Corporation, Columbus, Ohio A starting impulse generated when the crank shaft of [22] Filed, Apr 26 1973 an engine passes a specific point and starts a counter that counts impulses for one revolution. During the DM- 349 same revolution, another signal corresponding to a specific engine event starts another counter that con- [52] U S C] 235/92 FQ 235/92 C 235/92 CC tinues until the end of the same revolution. A comput- 235/92 235/92 ing circuit uses data from the counters to determine [5 1] Int Cl i103! 21/34 engine speed and the angle at which the engine event [58] Fie'ld CP 92 FQ occurs and presents this information as a numerical 235/92 readout. A mark signal may be generated as a cursor for cathode ray tube display of ignition or other en- [56] References Cited gine waveforms. The cursor can be moved to any point along the waveform by a manual control, and UNITED STATES PATENTS the angle at whatever point is selected will be presgfig gkgzg grakybrook 235/92 CV ented in the numerical readout,

,l c er 3,263,065 7/1966 Savage 235/92 CC 20 Claims, 8 Drawing Figures FREQuEMcY PER/OD GATE ScALER COUNTER /5 g l 250 KHz J CRYSTAL CLOCK l I /5 22 I Z3 24 ,L I r i r I GATE FREQUENCY up LIP-DOWN ScALER COUNTER l l l L- 1 II 20 Mum/WON COMPuTEpEQuENQE START WMING CONTROL. PULSE LOG/c COMPUTE SEQUENCE END GN/T/ON PULSE /9 MARK PuLsE GATE Z6 Z7 M PK .SINGLE 01v OFF 012 Z8 4-PERIOD AVERAGE Z E MANUAL. 4 CYCLE ENG/NE ENG/NE PATENTEB 1 I975 3. 870.869

SHL'EI l U? 6 Hzzausmy PER/OD GATE ScALER COUNTER F i i 250 KHz J cmsmz. I

CLOCK Z ZZ 24 i J I G fihsaumcv up LIP-DOWN SCALE/2 COUNTER i L i H F ZQ WM'WG g m COMPUTE [fizoumvcls START ONTROL. puLSE LOG/C Com/ un: SEQUENCE END 1 A 34 Z! IGN/T/ON /8 /9 MARK PULSE GATE q /Z5 J26 Z7 M RK SINGLE ON OFF I OR AVERAGE Z C Z I- MANUAL 4 CYCLE PATENTEDHARI I I975 3.870.869 SHEU 2 [1F 6 34 DATA REG/5T5? COMPUTE COMPUTE SEQUENCE SEQUENCE 3600 START END SELEC- T012 3/ I I7 I 5 %5 5 ON ETE PEQ/OD COUNT/5Q I LOG/C i TOf? I I I I 9 i 2 I BINARY UP-DOWN 5 722. RATE :DOWN COUNTEQ MULTIPLE I I I 38 I 39 l FREQUENCY OUTPUT 5cAI EI2 COUNTER ANGLE 1 SPEED ANGLE M EMOQY 5 PEED I A I DATA FQEAD ADDRESS 5PEE0 DATA 72 ENG/NE SWEEP GENERATOQ PATENTEDHARI 1 I975 3.870.869

SHEET 3 OF 6 43 SDPEED 5 4/4 ATA PEED RESET 4 CYCLE FROM COUNTER FROM ENG/NE COMDUTEF? COMPUTER TIMING 0360 Q 46 CONTROL PULSE 360- 720 SPEED LOAD LOG/C 7 52 REG/STEP? 65 V 5 45 VRESET y I 250 MH BINARY v SWEEP ENG/NE cRvsTAf RATE E X EEF CONT/20 SWEEP CLOCK MULTIPLIER COUNTER UNBLANKING 4 L/OGIC ENG/NE 59 r 54 W i /6c. BLAN I q 3 655%? DAG 02 5. 7 SIGNAL.

REFERENCE CONVERTER 6/ v [DANE/L A AL ENGINE FRONT VOLTAGE hfii 5WEEP CONTQOL 57 IQAMP 58 VOLTAGE COMPARATOR 7 PULSE G NE ATO;2 B S;

PATENTED HARI l IQTS SHEET b 0F 6 SWEEP TRIGGER r SELECT 5WEEP IOIv/T/OIv 5ELECTOR OR WMING 5W'TCH 65 64 67 gg 6 9 74 gELETED WE D g ft SELEC- RAMP 5WEEP RAMP 77 AT PTs E f E f; DEFLECTION 56 R Em AMPLIFIER T1 [1.4 72 VOLTAGE I COMPAPATOR+ gELECTED E72 76 E TEZ ea- 5 WEED CONTROL LOG/C RAMP TO EEFLECTION .MPLIFIERS ANGLE/SPEED ANGL$PEED/4O A A DATA I MEMORY 5 QEAD CE I. Tlg- 5CDATA ADDRE5$ UNBLANKING ANNER DATA 6 v I I I 50 7 I 3 Z MHE DSPLAV SEGMENT DIG/T AAOLE/S/ EED 3 55 COUNTER vCOUNTEQ SELECTOR 82 8;] V CNOR/z. I HARACTOQ gu/I/IEQIcs NUMEg/cs I DISPLAY WAVEF'ORM NABLE WAVEFORM D/G/T/ZER w GENERATOR 88 I VERT CHARACTOR I WAVEFORM PIIEIIIEII I I m 3.870.869

SHEET 5 [1F 6 TRACE I SELECT I I- 5 OR A MULTIPLEY MODE. CI-IoP OR ALTERNATE swap ELECTOR 99 WITCH I 532% \5AMPLEA SAMPLE A5 75 HORIZ. DISPLAY 5 MPLE CONTROL DEFLECT/ON AMPL/FEQ GENERATOR LOG/C 5ELEcTED -5WEEP /O/ I 4 TRIGGER 77Q/GGER IGNITION C/Rcu/T pULsE /06 INPUT 96 ATTENUATOR PREP i TRACE A AMPLIFIER v 9/ INPUT V/RAEE B I Q I //Z ATTENuATvR PRE- AN O DEELEET/ON "(Z TRACE B AMPLJFIER GATE AMPLJ/ /ER 94 COMPOSITE I 97 VERT SAMPLE VEFLECTION AvEEoRM N Q To VERT ANALOQ CHARACTOR I GATE WAVEFORM PATENTEU m1 1 I975 COMPOSITE DEFLECTIOA/ AMPL/F/ER WA VEFORM 2 C I.

Tiq E mz UNBLAN KNG SHEET '6 IF 6 A SAMPLE A FROM VER DEFLECTION AMP.

x 6 SELECTED ANAL-0G SWEEP GATE //8 RAMP H7 INVERTER IZZ r H0212. k ANAL-0G CHARACTER GATE /Z/ WAVEFORM /3/ 5WEEP 551.50 DATA 7 /Z4 7Z2AcE SELEcT DATA /25 EAST Sweep UNDLAN UNBLANKING /Z6 'MARIC Puma: /z9 1 SINGLE/NORMAL. V B3 TRALZE CONTROL. L m,

AMPLIFIER BACKGROUND OF THE INVENTION This invention relates to the field of analyzers for internal-combustion, piston engines, and in particular, it relates to the field of analyzers with digital readout of speed and angular information. I

Most commercially available engine analyzers heretofore have merely indicated the waveform of ignition pulses by means of a conventional Oscilloscope with special probes. In general, they are not suitable for accurately timing an engine nor for use with condenser discharge ignition (CDI) systems. Also, with multicylinder engines, it is possible to time the No. l cylinder correctly and yet have an error of several degrees on other cylinders. On large engines timing often takes two people: one to read the timing light and another to adjust the angle, for the timing marks and the ignition.

advance adjustment are often at opposite ends of the engine. Convenient and safe access to the timing marks is also often a problem.

One object of this invention is to provide an instrument that can be easily connected to an engine and, using digital circuits, will directly read timing advance angle to a high degree of accuracy. It has been proposed to control an analyzer by a stable but variable oscillator at 3,600 times engine speed. By gating a counter on and off with a magnetic pick-up positioned on the engine flywheel to detect top center, it was possible to set the oscillator at 3,600 times engine speed. This, in effect, divided the flywheel into 3.600 equal increments, each corresponding to 0.1 degree of crank angle. When this was done, the same counter was reset and used to count the oscillator pulses between the ignition pulse and top center. This was the timing angle in degrees and tenths. That system had several disadvantages. However, it was possible to time an engine without a timing light. It was also proposed to use a voltage controlled oscillator and phase lock it to the variations'in engine speed.

A disadvantage of the timing method just described is that the engine speed can vary slightly from the calibration rotation to the measurement rotation.

Therefore, another object of this invention is to provide an analyzer that calibrates and measures during the same rotation.

BRIEF DESCRIPTION OF THE INVENTION In accordance with this invention, a control circuit, actuated by a signal that occurs when the crankshaft reaches a specific position, such as the top dead center (TDC) of the No. 1 cylinder, allows fixed frequency pulses to be counted in a first counter until the next occurrence of the timing pulse. While the first counter is counting, the same pulses are gated through to a second counter starting with the occurrence of a signal that corresponds in time to a specific engine event, such as an ignition pulse for a specific cylinder, the timing of which is to be investigated. The second counter stops counting at the same time as the first. The total count in the first counter. is related to the speed of the engine, and the total count in the second counter, is related to the angle between the crankshaft position at the time of the signal being investigated and the position that corresponds to the timing pulse.

.2 After this pulse information has been stored in the counters, the angle and speed are computed. The angle is computed by causing a counter, for example the second counter, to count a selected number equal to that originally counted in the second counter. However, the

counting rate during computation is at a pulse repetition frequency that is a certain fraction of the clock pulse frequency at which the counting was first done. The fraction is proportional to the total value counted in the first counter and to the clock pulse frequency. The fractional rate is typically produced in a binary rate multiplier and is appliedto a down terminal of the second counter to count the number stored therein back to zero. While the second counter is counting to zero, a third counter is counting up from zero at a clock frequency. When the second counter reaches zero, the counting stops in the third counter and the count therein is transferred to the second counter, which is then caused to count again back to zero at the clock frequency. During this second count-down, the third counter is caused to count up at yet another rate, such that the final number on the third counter, when the second counter has returned to zero the second time, is exactly the number of degrees and decimal fraction of a degree between the crankshaft position at the time of occurrence of the specific engine event and the position of the crankshaft at the next timing pulse. This number is transferred to a storage device, leaving both the sec-ond and third counters clear.

The speed is calculated by loading a specific scaling constant into a counter, preferrably the second counter, and counting that number down to zero at a counting rate that is a fraction of the rate at which the original counting was done. This fraction is proportional to the rate at which the second counter was counted back to zero the first time. At the same time that the second counter is being counted from the specific number back to zero, the third counter is counting up from zero at a different rate, and the relationship between the counting rates is such that, when the second 'counter reaches zero, the number recorded in the third counter is equal to the speed in RPM of the crankshaft of the engine. I

The information thus determined for the speed and angle can be entered into a numerical display unit. In particular, it can be entered into a system that will deflect the electron beam of a cathode ray tube to trace out numbers on the screen, and these numbers can be viewed simultaneously with the'waveform of the ignition or other engine characteristic under investigation so that analysis of the engine includes angle and speed information along with waveform information, all capable of being viewed virtually simultaneously.

It should be noted that different clock frequencies can be used at different times. The following description will be made in relatively specific terms because it would be exceedingly complex to spell out on each occassion the possible variations, but such variations are within the contemplation of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the components used in obtaining the basic data according to the invention.

FIG. 2 is a block diagram of the components used in computing speed and angle according to the invention.

FIG. 3 is a block diagram of a system for generating a marker pulse according to the invention.

FIG. 4 is a block diagram of a sweep generating system as used with the system of this invention.

DETAILED DESCRIPTION OF THE INVENTION Data Acquisition Phase Within the analyzer, information is processed in two phases. In the first phase, data acquisition, two time intervals are measured automatically. During the second phase the measured data is processed by a special purpose computer for display. During the data acquisition phase, the crank rotation period is measured by the circuit shown in FIG. 1. Measurement of the crank rotation period begins with an acquisition control logic circuit 11, which may comprise a flip-flop circuit receives, by way of an input terminal 12, a timing pulse generated by any suitable means 13 and usually fixed so that it occurs when the No. 1 piston is at top dead center (TDC) position. This timing pulse causes the acquisition control logic circuit 11 to open a gate 14 by causing the flip-flop to change states. A fixed frequency clock 15, for example a crystal oscillator having a frequency of 250 KHZ, is connected to supply pulses at this frequency to the gate 14. The pulses that pass through the gate are applied to a frequency scaler 16 through which they may pass at the same frequency or at a frequency that is a fraction of the initial frequency. The pulses from the frequency scaler are applied to a first counter circuit 17 which is referred to as a period counter. When the second TDC pulse is received, the acquisition control logic circuit 11 closes the gate 14 so that no further pulses can pass through it to the counter 17. At that time the count n, stored in the counter 17 is proportional to the time required for thecrankshaft of the engine being analyzed to complete one revolution.

During the same revolution, a second pulse, which may be obtained from the ignition circuit via an input terminal 18, or a mark pulse generated in another portion of the analyzer and applied via an input terminal 19, is selected by a selector gate 21, which may be a single-pole-double-throw switch, and transmitted to the acquisition control logic circuit 11. The acquisition control logic circuit uses this latter pulse, for example in a second flip-flop circuit, to open a second gate 22, which then passes pulses from the clock to a second frequency scaler 23. The frequency scaler may pass the pulses at the same repetition rate or may divide them by an integral number. The output of the frequency scaler 23 is applied to the up count terminal of an updown counter circuit 24. This counter counts pulses from the time of the occurrence of the ignition or mark pulse to the time of occurrence of the second TDC pulse, which closes the gate 22 as well as the gate 14. Thus, on one crank rotation two time intervals are measured, the time T from one TDC to the next and the time r from the ignition or mark pulse, as selected by a manual control 25, to the following TDC.

There are several modes of operation of the data acquisition phase. The instrument can be used on two cycle or four cycle engines by actuating

manual selectors

26 or 27, respectively. If a four cycle engine is to be analyzed, time measurements are made only during those crank rotations in which ignition or mark pulses occur. For a two cycle engine, measurements can be taken during any crank rotation. The operator may also select single or four period average measurements. In the single mode clock pulses pass through to frequency scalers l6 and 23 unchanged and time measurements are taken in a single crank rotation. If a four period average is selected, the total count of four revolutions if scaled by four by the

frequency scalers

16 and 23. In effect the scalers apply the average of four measurements to the counters. The latter mode is advantageous when engine timing or speed is somewhat erratic. Although the computer circuitry automatically resets the counters when required, the operator may manually reset and restart the system from a reset button 28 lo cated on the instrument panel. An additional control is provided permitting the operator to selecteither the ignition pulse or the mark pulse. Selection and use of the mark pulse is described hereinafter.

COMPUTATION PHASE At the conclusion of the acquisition phase, the acquisition control logic circuit 11 sends a compute sequence start" signal through an output terminal 29 to a computation section shown in FIG. 2. The compute sequence start signal is applied to an input terminal 30 of a computer control logic circuit 31. During the computation phase the acquisition control logic circuit 11 is quiescent, and upon completion of the computation phase, a compute sequence end signal" is generated by the compute control logic circuit 31 and transmitted via an output terminal 33 to an input terminal 34 of the acquisition control logic circuit 11 in FIG. 1 to reactuate the data acquisition phase and cause new measurements to be taken. The alternate acquisition and computation process is repeated as long as the instrument is connected to the engine under test.

In the computation phase, information accumulated in the period counter 17 and up-down counter 24, both of which are also shown in FIG. 2, is processed into advance angle and engine speed. This is a three step serial process in which two steps are required to obtain the advance angle and one step for engine speed. The basic information is that count 11, stored in the period counter during one complete revolution is to 360 as the count n stored inthe up-down counter is to the advance angle a. Or:

For the speed, a count N is obtained that is simply:

where k is a constant.

Upon receipt of the compute sequence start pulse, the computer control logic circuit 31 causes the number 11,, accumulated in the period counter 17, to be stored in the data register 34. This can be done by having the data register 34 non-destructively read the accumulated count in the counter 17. A binary rate multiplier 36 has one of its input terminals connected to the counter 17. The count stored in the counter 17 is presented as a parallel binary number. A second input to the binary rate multiplier 36 is a clock signalf from a clock 35, which can have a different frequency than the clock in 'FIG. 1. It is convenient for the frequency f, to be much higher, for example 1 MHz. The output signal of the binary rate multiplier 36 is a pulse signal given by the equation:

where n is the parallel binary number presented to the rate multiplier, n,,, is the maximum value n can have, as determined by the rate multiplier, and f is a' clock signal.

At this time in the computation sequence the output of the rate multiplier 36 is:

where n, is the number accumulated in the period counter 17 and is proportional to the crank rotation period, and n, is the maximum number that can be accumulated in the period counter. For an 18 bit counter, n,,, 2 -1=262,l43. The computer control logic 31 causes f to be routed through a reversing gate 37, which is basically a double pole-double-throw switch, to the down clock input of the up-down counter 24. The clock signal f, is routed through a frequency scaler 38 unchanged to an output counter 39.

The up-down counter 24, which contains the n information, counts down until zero is reached at which time the counting is stopped. The time I, required for the up-down counter 24 run-down is:

While the up-down counter 24 is counting down at the rate f,, the output counter 39 is counting up at the rate 1, and during the time t it accumulates the count n where:

It can be seen that a quantity proportional to n /n has been computed.

During the second step of the computation process the number n;, in the output counter 39 is parallel loaded into the up-down counter 24 and the output counter 39 is cleared. The period counter 17 is cleared and loaded with the number 3,600 from a data selector 41, which is essentially a single-pole-double-throw switch. This establishes an output f from the binary rate multiplier 36 where:

m 3600n /n Since the output counter 39 counts in binary coded decimaL m is the advance angle in tenths of a degree. The error in the above process is within fl.2. The advance angle number n. in the output counter 39 is then loaded into an angle/speed memory circuit 40 for future display. All counters 17, 24 and 39 are cleared and the computer control .logic circuit 31 proceeds to the third computation step.

The third and final computation step results in engine speed in RPM. The data selector 41 connects the data register 34 in which count n has been previously stored, so that n, is parallel loaded into the period counter 17. The output frequency of the binary rate multiplier 36 is: r

. gine under test.

fl l m fr A scaling constant 5722 is parallel loaded into the updown counter 24, and the computer control logic circuit 31 causes the signal f to be routed through the reversing gate 37 to the down clock input of the up-down counter 24. The number 5722 is determinted by the equationz'l RPS RPM K n,,,/f Since the data acquisition clock 15 in FIG. l has frequency of 250,000 pulses/second, and n is 262,143. K=57.22. Since the computation is on a fixed point basis, K=5722 is loaded into the counter 24. The 1 MHz clock signal is routed through the reversing gate 37 to the frequency scaler signal 38 where f, is divided by and applied to the output counter. The up-down counter 24 down counts from 5722 to 0 in a period of time t During the time interval t the output counter 39 is counting up. When the up-down counter 24 reaches 0 counting process ends. The contents of the output counter n is the speed in RPM:

The speed data is then loaded into the angle-speed memory for future display.

At the conclusion of the third step all counters 17, 24, and 39 are cleared and the compute sequence end pulse is issued to the acquisition control logic circuit 11 in FIG. 1. New data is acquired processed, and repeated as long as the instrument is connected to the en- Engine Sweep and Mark The purpose of the engine sweep is to provide a horizontal sweep rate proportional to crank rotation to display ignition and other waveforms on a cathode ray tube. A mark, appearing as a small bright spot in the cathode ray tube, is used to identify points of interest on the display in terms of crank angle. When the mark is not in use the angle computed and displayed is the ignition advance angle. When the mark is used, its position is controllable from the instrument panel and the angle computed is the advance angle of the mark referenced to the timing pulse.

Development of the engine sweep begins during the third step-of the computation phase in which engine speed is computed. While the output counter 39 is accumulating the speed count in RPM, a second output from'the frequency scaler 38 is providing speed data through a terminal 42 to the engine sweep section shown in FIG. 3. This speed data is a burst of clock pulses having a frequency scaled to f /20 and is connected by an input terminal 43 to a speed counter 44, which is accumulating a number porportional to engine speed. After this accumulation the number in the speed counter 44 is parallel loaded into a speed register 46. The speed counter is then reset in preparation for the next accumulation.

The contents of the speed register 46 is connected to a binary rate multiplier 47 along with a train of clock pulses, from the 250 KHz clock 15 to produce an output signal having a frequency f As a result of repeated speed computations and accumulations in the speed counter 44, the contents of the speed register 46, and therefore the frequency f,, is maintained proportional f,/9 by a frequency scaler 48 and is applied to a sweep control counter 49. The timing pulses which occur once for each engine crank rotation are also applied to the counter 49 through an input terminal 51 to reset it. Between timing pulses the sweep control counter 49 is accumulating a count at a linear rate. At any instant of time the contents of this counter is proportional to crank angle referenced to the timing pulse. Between timing pulses the cathode ray tube is unblanked. If the instrument is connected to a 4-cycle engine, the operator may select -3 60 or 360-720 by means ofa control 52. This permits viewing of either the first 360 or the second 360 of crank rotation. This is accomplished by the engine sweep unblanking logic circuit 53.

Digital information from the sweep control counter 49 is continuously applied to a digital-to-analog converter 54 where a staircase type waveform is produced. This waveform consists of 510 successively higher voltage steps. This signal passes through an analog scaling circuit 56 where it is scaled and smoothed into a linear ramp, or sawtooth, waveform to produce, at an output terminal 57, the engine sweep.

The mark is produced from the engine sweep ramp applied to a voltage comparator 58. A second voltage, generated in a reference source 59 and adjustable from a front panel control 61, is also applied to the voltage comparator 58. When the difference between the two voltages is zero a pulse generator 62 produces the mark pulse at an output terminal 63. When the mark is being used, the mark pulse is substituted for the ignition pulse and the computed and displayed angle is the advance angle measure from the timing pulse to the mark.

Scaling of the engine sweep may be changed by a front panel control of the scaling circuit 56. The operator may select a horizontal magnification of six times normal. This This permits viewing any 60 sector of the crank rotation. Use of horizontal magnification and the mark permits the operator to identify in degrees of crank angle any point of interest on the cathode ray tube trace. K

Fast Sweep Generator When the engine sweep is not employed, the fast sweep generator shown in FIG. 4 may be selected. This generator produces a fast linear time base for observing such phenomenon as primary or secondary ignition waveforms.

Fast sweep ramps are initiated by trigger pulses. The trigger source may be either ignition pulses applied to a terminal 64 or timing pulses applied to an input terminal 66, depending on the setting of a control 65. The selected trigger pulses pass through the selector gate 67, which is basically a single-pole-single-throw switch, and set an RS flip-flop 68. The low-going output of the flip-flop 68 permits a capacitor in a ramp generator 69 to charge at a linear rate. The rate at which it charges is controlled by a sweep selector switch 71 located on the instrument panel.

A reference voltage is applied through an input terminal 72 to a voltage comparator 73, and the output of the ramp generator 69 is also applied to the same comparator. When the ramp voltage equals the reference voltage, the voltage comparator resets the flip-flop 68 and the capacitor is discharged. At this time the generator is ready for the next trigger pulse which starts the process over again. A sweep select circuit 74 in conjunction with the sweep selector switch 71 provides a means for selecting either engine sweep, via the terminal 76, or fast sweep. The selected sweep is routed through an output terminal 77 to the horizontal deflection amplifier.

Digital Display Generator The digital display generator in FIG. 5 provides two functions: multiplexing of all information displayed on the cathode ray tube, and the generation of digital display waveforms. A display multiplex control 79, which is essentially a 3-position switch and is driven by the 250 KHz clock 15, sequentially controls the generation of the numerics waveforms and the sampling of the vertical inputs, trace A and trace B. A segment counter 81 clocked by the display multiplex control provides three bit binary number to control the operation of a numerics waveform generator 82. This circuit generates the vertical and horizontal deflection waveforms required to produce the seven number segments on the cathode ray tube. The three hit number also addresses a data scanner 83 where data from the angle/speed memory 40 is converted to the cathode ray tube unblanking waveform. A clock pulse from the segment counter 81 up-dates a digit counter 84, which, after each count of 4, updates an angle/speed selector 86. The contents of the digit counter 84 and angle/speed selector 86 provide the read address for the angle/speed memory 40. This read address is also applied to a display digitizer 87 in which analog gates apply stepping voltages via an output terminal 88 to step the digits sequentially across the face of the cathode ray tube. The vertical deflection voltages for numerals are supplied from the numerics waveform generator 82 via an output terminal 89.

Vertical Deflection Amplifier The vertical deflection amplifier in FIG. 6 provides the necessary signal amplification and control to move the electron beam vertically in the cathode ray tube. Instrument input waveforms, trace A and trace B, received at terminals 91 and 92 pass through their

respective attenuators

93 and 94 and

preamplifiers

96 and 97 where deflection scaling in volts per centimeter is accomplished. A control logic circuit 98 may operate in either oftwo modes. In the multiplex mode, sampling pulses from the digital display generator via

input terminals

99 and 101 cause a rapid sequential sampling of trace A, trace B, and the vertical character waveform. In the alternate mode, trace A is displayed completely followed by trace B and digital information is painted in a time interval between traces. A sweep selector switch 102 establishes the control logic mode. A trace select switch control 103 on the instrument panel permits selection of trace A only, trace B only or both traces. An ignition pulse is developed from the trace A signal by a trigger circuit 104. This pulse is applied through a terminal 106 to both the computer and the fast sweep logic. The sequential deflection signals as assembled by analog gates 107-109 pass through a deflection amplifier 111, where final amplification provides the necessary deflection signal to an output terminal 112.

Horizontal Deflection Amplifier FIG. 7 shows the horizontal deflection section in which signals representing sampling of trace A and trace B are applied through an input terminal 114 to an sweep ramp is applied by way of another input terminal 118 to the analog gate 116, and the gate output signal is connected to deflection amplifier 119.

At specific times the electron beam has tobe defiected to trace out numerical characters, and signals for this purpose are applied to an input terminal 121 from which they are connected to another analog gate 122. The gating signals are obtained from the inverter 117, and the gated output signal is connected to the deflection amplifier 119. The output of the amplifier 119 controls horizontal deflection of the cathode ray tube beam.

Unblanking Control The unblanking circuits in FlG. 8 combine unblanking signals applied to terminals 124-l29 and conditions necessary to turn on and off the cathode ray tube beam. There are two modes of operation. During the normal mode, an unblanking combinational logic circuit 131 combines un'blanking pulses from the fast sweep, engine sweep and data display generator circuits with sweep and trace select conditions. A train of pulses of proper widths and timing are amplified by an unblanking amplifier 132 which causes the cathode ray tube beam to be gated on and off. The mark pulse, described previously, is also applied and when processed through the circuitry, causes a higher beam current to occur during mark pulse time. This results in an intensified spot on the cathode ray tube traces. A second mode of operation is provided permitting the instrument operator to disable the unblanking circuits. Upon depressing a spring loaded switch located on the instrument panel, an unblanking control 133 will actuate a single trace logic circuit 134 to cause a one complete paint of all traces and digital data on the cathode ray tube. This mode is employed during photography when a permanent record of the total display is desired.

What is claimed is:

1. Digital analyzing means for a rotating body, said 4 means comprising:

A. clock signal source means to produce fixed repetition rate clock signals;

B. a first counter;

C. first connecting means to connect said first counter to said source means to count a first number :1 of said clock signals at a repetition rate off while said body-rotates through a first angle;

D. a second counter;

E. second connecting means to connect said second counter to said source means to count a second number in of said clock signals at a rate of kf proportional to the repetition rate f while said body rotates through a second angle;

F. first signal generating means'connected to said clock signal source means to generate a first signal having a repetition rate f proportional to the repetition rate f and to said-number n, and inversely proportional to a maximum count .n,,,;

G. means connected to said first signal-generating means to count a selected number a atsaid repetition rate f to establish a first time interval t, n /f,;

H. second signal-generating means connected to said clock signal source means to generate a secondsignal having a repetition rate f2; and

l. means connected to said second signal-generating means to count from zero to a number n at a rate f for said time 1 such that n, t f is a measure of angular rotation of said rotating body. 1

2. The analyzing means of claim 1 in which said first connecting means comprises:

5 A. means to generate a timing pulsesignal each time said rotating body passes a predetermined angular position; and

-B. gating means opened by selected ones of said timing impulse signals and closed by the succeeding timing impulse signal, whereby said first angle is 360.

3. The dig-ital analyzing means of claim 2 in which 4. Thedigital analyzing means of claim 3 in which f I/ mfc- 5. The analyzing means of claim 2 in which said selected number n,-, is 60f /n and said rate f is proportional to the rate f whereby said number 11 is the num; ber of revolutions per minute of said body.

6. The analyzing means of claim 5 in which said means to count from zero to a number n comprises a sealer circuit having a scaling ratio r, whereby f =f /r.

7. The analyzing means of claim 6 in which r=l00.

8. The digital analyzing means of claim 5 in which said means to count a selected number n;, comprises said second counter and said means to count from zero to a number n comprises a third counter.

9. The digital analyzing means of claim 8 in which said second counter is an up-down counter comprising means to parallel-load said number n therein.

10. The digital analyzing means of claim 2 in which:

A. said second connecting means comprises second gating means that opens at a particular point in a revolution of said body to start the count of n at a particular engine event and closes simultaneously with said first-named gating means;

B. n =n and 11. The digital analyzing means of claim 1 in which n =n and-f is proportional to 3600]} and inversely proportional to n,,,, whereby said number 11 is a measure of the angle through which said body rotates while said second counter is counting n 12. The digital analyzing means of claim 1 in which said first signal-generating means comprises a binary rate multiplier having a maximum count it, higher than any number n or 3600 to be entered into it.

13. The digital analyzing means ofclaim 12 in which:

A. said first connecting means comprises:

1. means to generate a timing impulse signal each time said rotating body passes a predetermined angular position, and

'2. first gating means opened by selected ones of said timing impulse signals and closed by the succeeding timing impulse signal, whereby said first angle is 360;

B. said second counter is an up-down counter comprising an up input terminal and a down input terminal; and

C. said second connecting means comprises second gating means opened at a time corresponding to a selected event during a rotation of said body and closed simultaneously with said first gating means and connecting said clock signal source means to said up input terminal.

14. The digital analyzing means of claim 13 in which said means to count a selected number 11 comprises said second counter, said binary rate multiplier being connected to said down input terminal to count said number n down to zero at a rate f proportional to the number n, and to said repetition rate f and inversely proportional to said maximum count n 15. The digital analyzing means of claim 14 in which said means to count from zero to a number )1, comprises a third counter.

16. The digital analyzing means of claim 15 comprising, in addition:

A. means connecting said clock signal means to said third counter to count up from zero while said counter is counting said number n down to zero;

B. means to transfer the count from said third counter to said second counter when said second counter reaches zero;

C. means to modify the ratio in said binary rate multiplier to produce an output signal having a repetition rate f proportional to 3600 f and inversely proportional to n,,, and to cause said counter to count down to zero a second time at said rate f and D. means to connect said clock signal source means to said third counter to count up from zero to said number n, at said rate f 17. The digital analyzing means of claim 12 comprising, in addition:

A. a data register having an input connected to said first counter to record the number m;

B. a data selector connected to said data register to select either said number n or the number 3600; and

C. means connecting the output of said data selector to said first counter to enter said number 3600 into said counter or to reenter said number n into said counter.

18. The digital analyzing means of claim 12 comprising, in addition:

A. means to generate a sweep ramp signal synchronously with said timing pulses; and

B. means comprising a voltage comparator and a reference voltage source to generate a mark pulse at any selected point along said ramp and means to use said mark pulse to initiate the counting of said second number n in said second counter.

19. The process of analyzing angular rotation of a body comprising the steps of:

A. counting a series of pulses of a first fixed repetition ratef said counting beginning when said body reaches a predetermined angular position and ending when said body again reaches said predetermined angular position, the number of said pulses counted being defined as n B. subsequently establishing a time interval t, by

counting a selected number n of pulses of said series of pulses multiplied by a selected ratio to have a second repetition rate f proportional to said first repetition rate and proportional to the number n in said first series and inversely proportional to a maximum count n,,,, whereby t n n ln f and C. counting a series of clock pulses for a time interval that has a duration equal to the time it takes to count said selected number n of pulses, the repetition rate of said clock pulses being proportional to the repetition rate of said first pulses, and said selected number n being proportional to the repetition rate of said clock pulses such that said lastnamed count n of said clock pulses is a measure of the angular rotation of said body.

20. The process of claim 19 comprising the additional steps of:

A. counting a sub-series n of said first-named pulses at said rate f beginning after said body has passed said predetermined angular position and ending when said counting of said series of pulses ends; and

B. selecting'the number n of said pulses of said subseries to count at said second rate f,, whereby the number of clock pulses counted during the count of said sub-series represents the angle of rotation of said body during the counting of said sub-series.

l l l

Claims

1. Digital analyzing means for a rotating body, said means comprising: A. clock signal source means to produce fixed repetition rate clock signals; B. a first counter; C. first connecting means to connect said first counter to said source means to count a first number n1 of said clock signals at a repetition rate of fc while said body rotates through a first angle; D. a second counter; E. second connecting means to connect said second counter to said source means to count a second number n2 of said clock signals at a rate of kfc proportional to the repetition rate fc while said body rotates through a second angle; F. first signal generating means connected to said clock signal source means to generate a first signal having a repetition rate f1 proportional to the repetition rate fc and to said number n1 and inversely proportional to a maximum count nm; G. means connected to said first signal-generating means to count a selected number n3 at said repetition rate f1 to establish a first time interval t1 n3/f1; H. second signal-generating means connected to said clock signal source means to generate a second signal having a repetition rate f2; and I. means connected to said second signal-generating means to count from zero to a number n4 at a rate f2 for said time t1 such that n4 t1f2 is a measure of angular rotation of said rotating body.

2. The analyzing means of claim 1 in which said first connecting means comprises: A. means to generate a timing pulse signal each time said rotating body passes a predetermined angular position; and B. gating means opened by selected ones of said timing impulse signals and closed by the succeeding timing impulse signal, whereby said first angle is 360*.

2. first gating means opened by selected ones of said timing impulse signals and closed by the succeeding timing impulse signal, whereby said first angle is 360*; B. said second counter is an up-down counter comprising an up input terminal and a down input terminal; and C. said second connecting means comprises second gating means opened at a time corresponding to a selected event during a rotation of said body and closed simultaneously with said first gating means and connecting said clock signal source means to said up input terminal.

3. The digital analyzing means of claim 2 in which k 1.

4. The digital analyzing means of claim 3 in which f1 n1/nmfc.

5. The analyzing means of claim 2 in which said selected number n3 is 60fc/nm and said rate f2 is proportional to the rate fc, whereby said number n4 is the number of revolutions per minute of said body.

6. The analyzing means of claim 5 in which said means to count from zero to a number n4 comprises a scaler circuit having a scaling ratio r, whereby f2 fc/r.

7. The analyzing means of claim 6 in which r 100.

8. The digital analyzing means of claim 5 in which said means to count a selected number n3 comprises said second counter and said means to count from zero to a number n4 comprises a third counter.

9. The digital analyzing means of claim 8 in which said second counter is an up-down counter comprising means to parallel-load said number n3 therein.

10. The digital analyzing means of claim 2 in which: A. said second connecting means comprises second gating means that opens at a particular point in a revolution of said body to start the count of n2 at a particular engine event and closes simultaneously with said first-named gating means; B. n3 n2; and C. f2 3600fc/nm

11. The digital analyzing means of claim 1 in which n3 n2 and f2 is proportional to 3600fc and inversely proportional to nm, whereby said number n4 is a measure of the angle through which said body rotates while said second counter is counting n2.

12. The digital analyzing means of claim 1 in which said first signal-generating means comprises a binary rate multiplier having a maximum count nm higher than any number n1 or 3600 to be entered into it.

13. The digital analyzing means of claim 12 in which: A. said first connecting means comprises:

14. The digital analyzing means of claim 13 in which said means to count a selected number n3 comprises said second counter, said binary rate multiplier being connected to said down input terminal to count said number n2 down to zero at a rate f1 proportional to the number n1 and to said repetition rate fc and inversely proportional to said maximum count nm.

15. The digital analyzing means of claim 14 in which said means to count from zero to a number n4 Comprises a third counter.

16. The digital analyzing means of claim 15 comprising, in addition: A. means connecting said clock signal means to said third counter to count up from zero while said counter is counting said number n2 down to zero; B. means to transfer the count from said third counter to said second counter when said second counter reaches zero; C. means to modify the ratio in said binary rate multiplier to produce an output signal having a repetition rate f2 proportional to 3600 fc and inversely proportional to nm and to cause said counter to count down to zero a second time at said rate f2; and D. means to connect said clock signal source means to said third counter to count up from zero to said number n4 at said rate f2.

17. The digital analyzing means of claim 12 comprising, in addition: A. a data register having an input connected to said first counter to record the number n1; B. a data selector connected to said data register to select either said number n1 or the number 3600; and C. means connecting the output of said data selector to said first counter to enter said number 3600 into said counter or to reenter said number n1 into said counter.

18. The digital analyzing means of claim 12 comprising, in addition: A. means to generate a sweep ramp signal synchronously with said timing pulses; and B. means comprising a voltage comparator and a reference voltage source to generate a mark pulse at any selected point along said ramp and means to use said mark pulse to initiate the counting of said second number n2 in said second counter.

19. The process of analyzing angular rotation of a body comprising the steps of: A. counting a series of pulses of a first fixed repetition rate fc, said counting beginning when said body reaches a predetermined angular position and ending when said body again reaches said predetermined angular position, the number of said pulses counted being defined as n1; B. subsequently establishing a time interval t1 by counting a selected number n2 of pulses of said series of pulses multiplied by a selected ratio to have a second repetition rate f1 proportional to said first repetition rate and proportional to the number n1 in said first series and inversely proportional to a maximum count nm, whereby t1 n2nm/n1fc; and C. counting a series of clock pulses for a time interval that has a duration equal to the time it takes to count said selected number n2 of pulses, the repetition rate of said clock pulses being proportional to the repetition rate of said first pulses, and said selected number n2 being proportional to the repetition rate of said clock pulses such that said last-named count n3 of said clock pulses is a measure of the angular rotation of said body.