`
`RS1040
`Rohde & Schwarz Gmbh & Co., KG vs. Tektronix, Inc.
`IPR2018-00643
`
`
`
`US 7,860,674 B2
`Page 2
`
`DE
`EP
`EP
`EP
`
`FOREIGN PATENT DOCUMENTS
`69322530 T
`9/1999
`0279480
`4/1993
`0554973
`8/1993
`0740161 A2
`10/1996
`OTHER PUBLICATIONS
`
`J., “Zeitintervall-Messgenauigkeit von Digital-Oszil-
`Hancock,
`loskopen,” Elektronik, Weka Fachzeitschriftenverlag, Poing, DE,
`vol. 37, No. 1, Jan. 8, 1988, pp. 94-97, XP000955160, (No transla-
`tion).
`
`Jul.
`“Bisection method”
`2004, Wikipedia,
`26,
`[online]
`XP0023 89052, Retrieved from the Internet: URL:http://Web.archive.
`org/web/20040726154027/http://en.Wikipedia.org/Wiki/
`Bisectionimethod> [retrieved on Jul. 5, 2006].
`International Preliminary Report on Patentability for Application No.
`PCT/EP2006/006368, mailed Jun. 19, 2008.
`PCT/EP2006/003756 International Preliminary Report on Patent-
`ability (IPRP) dated Jul. 17, 2008.
`
`* cited by examiner
`
`2
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 1 0f 17
`
`US 7,860,674 B2
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`
`
`(Prior art)
`
`
`
`
`thresholdl
`
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`
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`Fig. 2
`(Prior art)
`
`3
`
`3
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`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 2 0f 17
`
`US 7,860,674 B2
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`U.S. Patent
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`Dec. 28, 2010
`
`Sheet 3 of 17
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`US 7,860,674 B2
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`Dec. 28, 2010
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`Sheet 5 of 17
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`Dec. 28, 2010
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`Sheet 6 of 17
`
`US 7,860,674 B2
`
`Fig. 7A
`
`29
`
`7, 7', 7”
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`Unitforgenerating
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`
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`
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`8
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`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 7 0f 17
`
`US 7,860,674 B2
`
`S
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`triggering signals
`
`
`Stat
`
`9
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 8 0f 17
`
`US 7,860,674 B2
`
`
`
` Stu
`with athreshold value swi
`
`
`
`identification of an overshooting
`threshold value SWi by the reference signal Si
`
`
`
`--
`
`7
`
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`
`C13 PM}
`
`830 '
`
`340
`
`850
`
`
`
`
`
`
`
`
`Determination of equidistant, additional sampled
`values _S_ i' between the two sampling points of the
`reference signal 8; before and after the overshooting or
`undershooting of the threshold value SWi by
`means of interpolation in a polyphase filter
`
`
`
`
`
`
`
`
`
`Comparison of all additional sampling times _S_; with I
`the threshold value SW:
`
`
`
` Determination the additional sampled values _S_ gjj'
`
`
`of all the additional sampled values § 5' with the
`shortest distance from the threshold value SW3
`
`
`as the sought-after triggering time
`
`
`
`Fig. 8A
`
`10
`
`10
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 9 0f 17
`
`US 7,860,674 B2
`
` .’7 Start
`
`V
`of the reference signal S;
`with a threshold value SWi
`
`5110'" '
`
`oevhootringo underooshtig '
`
`'
`of the threshold value SWi by the reference signal St
`
`
`;
`
`
`5120
`
`r
`
`‘ Determniation of the additional sampled value
`
`
`
`the middle ot the time interval observed in the
`
`respective iterative step by means of interpolation
`
`
`
`
`
`
`Si 30
`
`H Ceulation ot the Name between the determined
`
`
`additional sampled value Si," and the threshold value SW.
`.
`
`
`
`8140
`
`
`
`
`Comparison of the determined additional sampled
`value Stj' with reference to overshooting or undershooting
`
`the threshold value SWi
`
`
`
`
`
`
`8150
`
`
`
`
`
`Determination of the time interval halved on the left
`or right side of the additional sampled value 3i,j'
`
`
`
`determined in the current iterative step for the
`next iterative step dependent upon overshooting
`
`or undershooting ot the threshold value SWi
`
`
`
`
`Establishment of the additional sampled value S if
`determined in the current iterative step as the
`
`soughtatter triggering time
`
`
`
`
`Fig. 88
`
`End
`
`11
`
`11
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 10 0f 17
`
`US 7,860,674 B2
`
`Start
`
`8200
`
`’
`Werennal si
`W
`
`with a threshold value SWi
`
`82H] '
`
`'
`
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`
`ldentiticaontiot an overshooting or undershooting
`of the threshold value SWi by the reference signal Si
`
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`8220
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`
`Dtmnaerition of the additional sampled value SM' in
`the middle of the time interval observed in the
`respective iterative step by means of interpolation
`
`8230
`
`Calculation ol the distance between the determined
`additional sampled value Sit" and the threshold value SW
`
`8240
`
`
`
`3250
`
`
`
`
`Comparison of the determined additional sampled
`
`value Sit with reference to overshooting or undershooting
`the threshold value SW i
`
`3250
`
`527g
`
`Fig. BC
`
`
`
`
`
`Determination of the time interval halved on the left
`
`
`
`
`or right side oi the additional sampled value Styj'
`determined in the current iterative step for the
`next iterative step dependent upon overshooting
`or undershooting oi the threshold value SWi
`
`Determination oi the intersection between the reference signal
`S; and threshold value SW; as the triggering time of the triggering
`signal by means of linear interpolation from the additional
`sampled values 3i,j' and S 3114' in the last two iterative steps
`and their associated sampling times and the threshold value SWi
`
`End
`
`12
`
`12
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 11 0f 17
`
`US 7,860,674 B2
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`
`
`
`3300 ~ ~
`
`
`
`,. Srom
`Combining of several signals
`the signals _8_ to be presented with a reference signal Si
`
`
`
`
`
`tigring ignal STR with triggering
`
`:;
`time from the reference signal Si and threshold value SWi
`j
`
`
`
`
`
`
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`
`
`
`
`
`
`
`
`
`
`
`
`
`S4l0
`
`
`S310
`
`Fig. 9A
`
`8400
`
`Calculation of the respective triggering signal Sm ,
`STR2
`STRK with associated triggering time from
`the comparison of the reference signal
`81, 82
`SN with the threshold value SW
`
`Combining oi the individual triggering signal STRt ,
`8mg
`STRK to form an overall
`triggering signal Sm
`
`Fig. QB
`
`13
`
`13
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 12 0f 17
`
`US 7,860,674 B2
`
`
`
`8500
`
`Cobminingo
`
`f
`
`
`several triggering signals ~1, 82,...,
`g
`from all the signals 8
`
`to form a reference signal 87R,
`
`Still]
`
`,
`
`:
`
`Calculation of the respective triggering signal 8mg,
`STEM-+1: STRM+2 with associated
`triggering time from the comparison of the respective
`reference signal 85 , 8 M+1 ,
`SM+2 with the threshold SW,
`
`S520
`
`Combining of the individual triggerin signal STRi ,
`
`
`STRM+1 . STRM+2 to form an
`
`overall triggering signal Sm
`
`Fig. 90
`
`c,
`
`S600
`
`'7
`
`
`
` Calculation of the respective triggering signal STRit .
`STRiK with associated triggering time
`STFti2
`
`
`from the comparison of the relerence
`
`signal S; with the respective threshold
`
`value SW1 , SW2 ,..., SWK
`
`
`
`
`Combining of the individual triggerini;
`STRiz
`STRiK to form an overall
`
`triggering signal Sm
`
`
`
`
`
`
`14
`
`14
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 13 0f 17
`
`US 7,860,674 B2
`
` ComparrsonothereerenceSIgnal SI
`
`with atthreshold value SWI
`-
`
`
`
`
`Identification of two successive sampled
`
`
`values SII and SII-I of a reference signal SI ,
`
`both of which are disposed eitther below or above a
`
`
`
`thresholdvalue signal SWI
`
`S700
`
`S710
`
`8720
`
`~
`
`Determinattron of equidistant, additional sampled value SI7 " ‘
`
`
`between the two identified sampled values 8I and
`
`
`SII--1 of a reference signal by means of interpo ation
`
`
`onthebaSIsof polyphasefilters
`.
`
`$730
`
`'
`
`Comparison of the levels of all determined additional
`sampled value § I" with the threshold value SWI
`
`
`
`Dependent upon positive or negative slope triggering,
`identification of additional sampled values SII" and SII'I" with
`overshooting or undershooting of the threshold value 3ij ,and
`determinationfof the additional sampled value SI " or SII.I" which
`provides the shortest level difference relative to the
`
`threshold SWi , as the sought--atterttriggering time
`
`
`
`
`
`
`
`
`
`
`8740
`
`3750
`
`No
`
`
`
`
`Yes
`
`
`
`Triggering
`time identified ?
`
`»
`
`Generation of the triggering signal STR'"
`
`
`
`End
`
`,
`
`15
`
`15
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 14 0f 17
`
`US 7,860,674 B2
`
`S800"
`
`with a threshold value SWi
`
`
`
`8810'
`
`S820
`
`identification of two successive sampled
`values SH and 8 hit of a reference signal Si,
`both of wish are disposed either below or above a
`thresholdevalue signal SW;
`
`
` Determination of an additional sampled value 3 g "
`
`
`
`in the middle of the time interval observed in the
`respective iterative step by means of interpolation
`
`
`
`
`
`Establishment of the halved time interval disposed on the
`right or left side of the determined additional sampled
`
`value 3 i,j " for the next iterative step dependent upon the
`
`
`relatively shorter distance between the left or right-side
`sampled value Si i or SLi-i and the threshold value SW;
`
`
`
`
`
`iterative determination of the additional sampled value Sm
`
`of which the associated sampling time is the
`
`
`sought—alter triggering time
`
`3840
`
`3850
`
`3350
`
`,
`
`,
`
`Generation of the triggering signal S TRW
`
`Fig. 108
`
`End
`
`16
`
`16
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 15 0f 17
`
`US 7,860,674 B2
`
` 390i]
`
`
`retercene signal si
`>
`with a threshold value SW;
`.
`
`
`3910a
`
`'
`ldentificatinot two succesive
`values St; and S l 1-1 of a reference signal Si,
`both of which are disposed either below or above a
`threshold-value signal SWr
`
`' W
`
`_. ,,
`
`.
`
`
`
`..
`
`S920 '
`
`,. Deteiiionalspled valueSi’j
`in the middle of the time interval observed in the
`respective iterative step by means of interpolation
`
`
`
`
`
`"
`’ SW Sl,j*1’Si,j">SWi
`Yes
`
`
`oder
`Str’Sii-tsir‘SWt?
`
`
`
`
`
`
`
`
`8940
`
`- _50
`
`89
`
`Establishment of the halved time interval disposed on the
`right or left side of the determined additional sampled
`value S Li " for the next iterative step dependent upon the
`relatively shorter distance between the left or right-side
`sampled value Sit or Sit-1 and the threshold value SWi
`
`
`
`
`
`
`
`
`
`
`Iterative determination of the additional sampled value 8i i
`of which the associated sampling time is the
`sought-after triggering time
`
`
`
`
`
`8960
`
`
`
`
`Determination of the intersection between the reference signal Si
`and threshold value SW; as the triggering time of the triggering
`
`
`signal by means of linear interpolation from the additional sampled values
`S Li" and Sty-.1" in the last two iterative steps and their associated
`
`
`sampling times and the threshold value SW
`
`89.70
`Fig. 100
`
`,_
`
`7
`
`Generation oithe triggering signalSTR"'"
`
`End
`
`17
`
`17
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 16 0f 17
`
`US 7,860,674 B2
`
`.
`
`.. Sampling POW
`
`Threshold~value
`
`signal
`
`/ Triggering time
`
`Sampling point
`
`Additional sampling points
`
`
`//Triggeringtime
`
`
`
`
`
`Threshold value
`
`
`
`Sampling points
`
`18
`
`18
`
`
`
`US. Patent
`
`Dec. 28, 2010
`
`Sheet 17 0f 17
`
`US 7,860,674 B2
`
`Addlllenal sampled values
`
`Thrash/oldvalue
`Triggeringpaint /1\
`
`
`
`Sampled alues 3W ,3”
`
`Fig. 12A
`
`Additional sampled points
`
`Triggering point / i
`
`\
`
`Thrash/old value
`
`
`
`
`
`, S
`
`ampled values Sill ,Su
`
`Fig. 128
`
`19
`
`19
`
`
`
`US 7,860,674 B2
`
`2
`
`jitterifor
`conditions, or a statistical valueistatistical
`example, if stochastic phase noise is superposed on the mea-
`sured signal.
`In addition to these phase errors in the oscilloscope display
`resulting from time discretisation of the measured signal and
`stochastic phase noise ofthe measured signal, undesired jitter
`can also result from different delay times in the measurement
`channels ofmeasured signals, which are used in combination
`for checking the triggering condition. In this context, it is also
`a disadvantage that the triggering condition may not occur at
`all, and accordingly, the measured signals are not even pre-
`sented on the oscilloscope screen.
`The fact that phase and respectively time errors in the two
`paths of the measured signalianalog-digital converter or
`triggering systemiare mutually superposed and under
`extreme conditions can bring about a doubling of the effect
`can be seen as an additional disadvantage.
`DE 39 36 932 Al discloses a triggering-signal generator
`for an oscilloscope, which generates the triggering signal in a
`digital manner.
`
`10
`
`15
`
`20
`
`SUMMARY OF THE INVENTION
`
`1
`METHOD AND SYSTEM FOR SECURE
`DIGITAL TRIGGERING FOR AN
`OSCILLOSCOPE
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`The present application is a national phase application of
`PCT Application No. PCT/Ep2006/003756, filed on Apr. 24,
`2006, and claims priority to GermanApplication No. 10 2005
`035 473.4, filed on Jul. 28, 2005, the entire contents of which
`are herein incorporated by reference.
`
`FIELD OF THE INVENTION
`
`The invention, according to various embodiments, relates
`to triggering of an oscilloscope.
`
`BACKGROUND OF THE INVENTION
`
`Digital oscilloscopes as shown in FIG. 1 consist of an input
`amplifier, of which the variable amplification factor is used to
`match the amplitude ofthe measured signal to be displayed on
`the oscilloscope with the measurement range of the oscillo-
`scope; a downstream analog-digital converter for generating
`sampled values of the digitized measured signal; a recording
`unit for presenting over time the sampled values of the digi-
`tized measured signal; and a triggering system connected in
`parallel to the analog-digital converter for phase-corrected or
`respectively time-corrected presentation in the recording unit
`ofthe signal portion ofthe measured signal identified with the
`triggering threshold of the analog triggering system.
`Via several comparators, an analog triggering system
`shown in FIG. Zifor the sake of simplicity, only one mea-
`sured signal is used for triggering in the triggering system of
`FIG. Zicompares the measured signal present at the respec-
`tive input A, and pre-amplified with reference to its ampli-
`tude, in each case with reference to overshooting or under-
`shooting the level of a threshold-value signal present at the
`input B, in order to form complex triggering conditions. The
`respective, variable threshold values 1
`.
`.
`. N are stored in
`digitized form in a register. A triggering signal for the correct
`presentation of the required signal portion of the measured
`signal in the recording unit is generated in an evaluation unit
`connected downstream of the comparators dependent upon
`the respectively-set triggering condition and subject to the
`occurrence of the triggering condition.
`If the intersection of the threshold-value signal with the
`measured signal to be recordeditriggering pointiis dis-
`posed between two sampled values ofthe digitized, measured
`signal to be recorded, a triggering offset is provided, as shown
`in FIG. 3, between the triggering point and the next sampled
`value or respectively between the triggering point and the
`preceding sampled value of the digitized, measured signal to
`be recorded. This triggering offset leads to a phase offset in
`the presentation of the measured signal in the recording unit
`between the measured signal to be recorded and the coordi-
`nate origin of the recording unit.
`This phase offsetijitteribetween the measured signal to
`be recorded and the coordinate origin of the recording unit is
`also known in analog oscilloscopes and is presented in FIG. 4.
`In FIG. 4, a jitter of 0.3 display units on the screen of the
`oscilloscope is evident for a triggering threshold of 0 V.
`It is known from analog oscilloscopes that this jitter adopts
`either a constant valueisystematic jitter 7, if the distance
`between triggering point and the next sampled value of the
`digitized measured signal is largely unchanged under stable
`
`25
`
`30
`
`35
`
`40
`
`45
`
`In accordance with various embodiments of the invention,
`a triggering method, a triggering system and a corresponding
`digital oscilloscope are provided for a secure triggering, cor-
`responding to the selected triggering condition, ofthe record-
`ing of one or more measured signals on the display unit ofthe
`oscilloscope with a higher time resolution than the sampling
`rate of the analog-digital converter used in the digital oscil-
`loscope.
`According to an embodiment of the invention, a digital
`triggering system is used instead ofthe analog triggering with
`its associated disadvantages. In this context, during the trig-
`gering process, the sampled values of the digitized measured
`signal used as a reference signal are compared successively
`with a threshold value. According to a first embodiment ofthe
`invention, if an overshooting of the threshold value by the
`digitized reference signal occurs within two sampled val-
`uesifirst sampled value<threshold value, second sampled
`value>threshold value, or if an undershooting of the thresh-
`old-value signal by the digitized reference signal occurs
`within two sampled valuesifirst sampled value>threshold
`value, second sampled value<threshold value, the exact trig-
`gering time is determined by calculating several additional
`sampled values of the reference signal, which are disposed
`between the two sampling times at an equal distance from one
`another, and the exact time ofthe overshooting or undershoot-
`ing of the threshold value by the reference signal is deter-
`mined by a further comparison of all additional sampled
`values of the reference signal with reference to overshooting
`or undershooting the threshold value. In this manner, an
`occurring triggering offset can be minimized corresponding
`to the number of selected, additional, sampled values of the
`reference signal, which are calculated by means of interpola-
`tionipreferably by means of polyphase filter.
`According to a second embodiment of the invention, in
`order to minimize the number of additional sampled values of
`the reference signal to be calculated and therefore to realize a
`delay-time-optimized triggering, instead of a fixed number of
`additional sampled values of the reference signal, an addi-
`tional sampled value of the reference signal is calculated
`iteratively in each case in the middle of the time interval
`observed in the respective iterative step by means of interpo-
`lation with polyphase filters, and a comparison with reference
`to an overshooting or undershooting of a threshold value is
`implemented. Starting from the result of the comparisoni
`overshooting or undershootingi, the next iterative step uses
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`the halved time interval disposed on the left or the right side
`of the respective, additional, sampled value of the reference
`signal.
`According to a third embodiment ofthe invention, after the
`iterative halving of the time intervals corresponding to the
`second embodiment of the invention, an additional sampled
`value of the reference signal is calculated within the time
`interval of the last iterative step by means of linear interpo-
`lation.
`
`According to a fourth embodiment of the invention, if the
`triggering time between two respectively-successive sampled
`values of the digitized measured signal is erroneously not
`identified as a result of the absence of an overshooting or
`undershooting of the threshold value by the reference signal
`(threshold value is disposed either above or below two suc-
`cessive sampled values of the reference signal), additional
`sampled values of the reference signal should be calculated
`between the two sampling times by means of interpolation
`with polyphase filters, in order to identify a possible over-
`shooting or undershooting of the threshold value by two
`successive, (additional) sampled values of the reference sig-
`nal.
`
`According to a fifth embodiment of the invention, in order
`to minimize the number of additional sampled values of the
`reference signal to be calculated, the number of calculations
`to be implemented is significantly minimized by comparison
`with the fourth embodiment of the invention by iterative
`halving of the time interval, subsequent calculation of an
`additional sampled value of the reference signal disposed in
`the middle of the respective time interval and comparison of
`the additional sampled value of the reference signal with the
`threshold value.
`
`By analogy with the third embodiment of the invention,
`there is also a sixth embodiment, in which the additional
`sampled value ofthe reference signal is determined in the last
`iterative step by means of linear interpolation from the addi-
`tional sampled values ofthe reference signal calculated in the
`two preceding iterative steps by interpolation with a
`polyphase filter.
`In order to reduce the sensitivity ofthe triggering system, a
`comparison with two threshold valuesiequivalent to a com-
`parator with hysteresisiis implemented. In the case of an
`overshooting, the upper threshold value is used, while the
`lower threshold value is used in the case of an undershooting.
`Different delay times in the measurement channels associ-
`ated with the individual measured signals are registered via a
`calibration procedure and compensated in the individual
`measured signals, before the reference signal is determined
`from the individual measured signals for the digital triggering
`or respectively before the sampled values of the individual
`measured signals are presented on the screen of the oscillo-
`scope.
`
`Still other aspects, features, and advantages of the present
`invention are readily apparent from the following detailed
`description, simply by illustrating a number of particular
`embodiments and implementations, including the best mode
`contemplated for carrying out the present invention. The
`present invention is also capable of being embodied within
`other and different embodiments, and its several details can
`be modified in various obvious respects, all without departing
`from the spirit and scope of the present invention. Accord-
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`ingly, the drawings and description are to be regarded as
`illustrative in nature, and not as restrictive.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Various exemplary embodiments are illustrated by way of
`example, and not by way of limitation, in the figures of the
`accompanying drawings in which like reference numerals
`refer to similar elements and in which:
`
`FIG. 1 shows a block-circuit diagram of a conventional
`digital oscilloscope with an analog triggering system;
`FIG. 2 shows a block-circuit diagram of a conventional
`analog triggering system;
`FIG. 3 shows a conventional time characteristic of the
`
`digitized measured signal with triggering offset, according to
`an exemplary embodiment;
`FIG. 4 shows a conventional graphic presentation of a
`display device of an oscilloscope with an erroneously-pre-
`sented measured signal with analog triggering, according to
`an exemplary embodiment;
`FIG. 5 shows a block-circuit diagram of a digital oscillo-
`scope with digital triggering system, according to an exem-
`plary embodiment;
`FIGS. 6A, 6B, 6C show block-circuit diagrams of a the
`first, second and third embodiments of a unit for generating
`digital triggering signals, according to certain embodiments;
`FIGS. 7A, 7B, 7C and 7D show block-circuit diagrams of
`a the first, second, third and fourth embodiments of a system
`for digital triggering;
`FIGS. 8A, 8B, 8C show flow charts of a the first, second,
`and third embodiments of a method for generating digital
`triggering signals;
`FIGS. 9A, 9B, 9C and 9D show flow charts of a the first,
`second, third and fourth embodiments of a method for digital
`triggering;
`FIGS. 10A, 10B and 10C show flow charts of the fourth,
`fifth and sixth embodiments of a method for generating digi-
`tal triggering signals;
`FIGS. 11A, 11B show a time characteristic ofthe digitized,
`measured signal according to the first and second embodi-
`ments of the method or respectively system for digital trig-
`gering; and
`FIGS. 12A, 12B show a time characteristic of the digitized
`measured signal according to the fourth and fifth embodi-
`ments of the method or respectively system for generating
`digital triggering signals.
`
`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`The digital oscilloscope shown in FIG. 5 matches the
`amplitude level of the measured signal disposed at its input
`with the measurement range of the display device 5 using a
`pre-amplifier 1, which provides a variable amplification fac-
`tor. After the level matching, the pre-amplified, analog mea-
`sured signals are supplied to an analog-digital converter 2 for
`conversion into a corresponding digital data format.
`An adjacent unit for compensation of delay times 3 com-
`pensates different delay times in the measurement channels
`associated with the individual measured signals. An equalizer
`system 4, which implements an equalization of the linear, or
`respectively non-linear, distorted, digitized measured signals
`is optionally disposed downstream. The linear or respectively
`non-linear distortions of the measured signals result from the
`transmission behaviour of the transmission elements of the
`
`measurement channel as a whole (sensors, measurement
`lines, pre-amplifier and analog-digital converter).
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`US 7,860,674 B2
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`5
`After the equalization, the digitized measured signal is
`checked by a digital triggering system 5 with reference to an
`adjustable triggering condition, and in the case of an identi-
`fication of this triggering condition, a triggering signal for
`triggering the digital oscilloscope is generated in the mea-
`sured signal at the output of the digital triggering system 5.
`Those sampled values of the digitized, equalized measured
`signal, which are registered simultaneously with the trigger-
`ing signal or immediately following the triggering signal in
`time, are presented on a screen of the recording unit 6 of the
`digital oscilloscope.
`third and fourth
`Before describing the first, second,
`embodiments of the system for digital triggering with refer-
`ence to FIGS. 7A, 7B, 7C and 7D of the drawings, the fol-
`lowing section presents the first, second and third embodi-
`ments of a unit for generating triggering signals, which is
`incorporated alternatively in all of these embodiments of a
`system for digital triggering, with reference to FIGS. 6A, 6B,
`6C:
`
`In a first embodiment 7 of a unit for generating digital
`signals shown in FIG. 6A, one signal S from several signals
`S to be presented in a digital oscilloscope is used as a refer-
`ence signal S for generating a triggering signal S TR. For this
`purpose, the sampled values Si,j of the reference signal SI. and
`a threshold value SW1. are supplied respectively to an input of
`a comparator 8. The comparator 8 compares the sampled
`value Si,1. ofthe digitized reference signal S with the threshold
`value SW1. and activates a first output in the case of an over-
`shooting of the threshold value SW1. by the sampled value Si,1.
`of the reference signal 8,, or respectively a second output, in
`the case ofan undershooting ofthe thresholdvalue SW1. by the
`sampled value Si,1. of the reference signal 8,.
`In a slope detector 9 connected downstream of the com-
`parator 8, dependent upon a positive or negative slope trig-
`gering and upon the two signals at the two outputs of the
`comparator 8, an overshooting or undershooting of the
`threshold value SW1. by two successive sampled values Si,1.
`and Sid.+1 of the reference signal S is identified by an activa-
`tion of the output of the slope detector 9.
`
`The sampled values Sig]. of the reference signal S are sup-
`plied to a unit 13 for determining additional, sampled values
`Si' of the reference signal S disposed at an equal distance
`between two successive sampled values Si,1. and SJ._ 1. This
`unit 13 consists of the actual interpolator 132, which is pref-
`erably a polyphase filter, and a unit 131 for controlling the
`interpolator.
`The unit 131 for controlling the interpolator reads in the
`individual sampled values Si] of the reference signal S in a
`cyclical manner and buffers them. The output signal of the
`slope detector 9 activated in the case of an overshooting or
`undershooting of the threshold value SW1. by two successive
`sampled values SiJ and Sid;l ofthe reference signal Si is used
`by the unit 131 for controlling the interpolator 132 for the
`sequential transfer to the interpolator 13 2 ofa given number of
`sampled values Sig]. ofthe reference signal 8,, which have been
`read in and buffered, and which are disposed before or respec-
`tively after the identified slope event. Additionally, the unit
`131 for controlling the interpolator transfers to the interpola-
`tor 132 the associated filter coefficients K. for the calculation
`of the respective additional sampled value SiJ' of the refer-
`ence signal S. The additional sampled value SiJ' of the ref-
`erence signal S calculated in each case by the polyphase filter
`13 2 is read in and buffered by the unit 131 for controlling the
`interpolator. When all of the additional sampled values SiJ' of
`the reference signal S have been calculated by the interpola-
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`tor 132, the unit 13 1 for controlling the interpolator outputs all
`calculated and buffered additional sampled values Si' of the
`reference signal 8,.
`The additional sampled values Si' of the reference signal S
`are read into a downstream comparator 14 and compared in
`each case with the threshold value SW,. The comparator 14
`provides for each of the additional sampled values Si' of the
`reference signal S respectively two outputs, of which one
`output is activated in the case of an overshooting of the
`threshold value SW1. by the additional sampled value SiJ' of
`the reference signal 8,, and the other output is activated
`respectively in the case of an undershooting of the threshold
`value SW1. by the additional sampled value SiJ' of the refer-
`ence signal S.
`Dependent upon a positive or negative slope triggering and
`upon the signals disposed at the individual outputs of the
`comparator 14, a final evaluation logic unit 15 determines the
`additional sampled value SiJ' ofthe reference signal 8,, which
`provides the shortest distance from the threshold value SW1.
`and which represents the sought-after triggering time for the
`triggering signal STR.
`In order to minimize the plurality of necessary additional
`sampled values Si' of the reference signal SI. of the first
`embodiment 7 of a unit for generating triggering signals, a
`second embodiment 7' of a unit for generating triggering
`signals is described below with reference to FIG. 6B, which
`requires a minimised number of additional sampled values Si'
`of the reference signal SI. for the determination of the trigger-
`ing time.
`In a manner equivalent to the first embodiment 7 of the unit
`for generating triggering signals, the second embodiment 7'
`of the unit for generating triggering signals compares the
`individual sampled values SiJ of the reference signal S,
`which are selected from several signals S to be presented on
`the digital oscilloscope, with the threshold value SW1. in a
`comparator 8'. The comparison leads to an activation of a first
`output of the comparator 8' in the case of an overshooting of
`the threshold value SW1. respectively by two successive
`sampled values Si ,1. and Sly; 1 of the reference signal 8,, and to
`an activation of a second output of the comparator 8' in the
`case of an undershooting of the threshold value SW1. respec-
`tively by two successive sampled values SiJ and Sig];l of the
`reference signal 8,. A slope detector 9' connected downstream
`ofthe comparator 8' determines from the two signals disposed
`at the first or second output of the comparator 8', whether,
`dependent upon a positive or negative slope triggering, an
`overshooting or an undershooting of the threshold value SW1.
`respectively by two successive sampled values Si,1. and Sig];l
`ofthe reference signal SI. is present and activates the output of
`the slope detector 9' in the case of an overshooting or under-
`shooting.
`The sampled values Si,1. of the reference signal S are sup-
`plied to a unit 13' for determining additional sampled values
`Si' ofthe reference signal Si disposed between two successive
`sampled values Si,1. and $1.314. This unit 13' consists of the
`actual interpolator 13 2', which is preferably a polyphase filter,
`and a unit 131, for controlling the interpolator.
`In a first iterative step, by analogy wit
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