CA1052473A - Methods and apparatus for recording well logging measurements - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
In accordance with illustrative embodiments of the present invention, well logging data in analog or digital form is recorded by a cathode ray tube recorder. A rep-resentation of the CRT beam is repetitively swept across a recording medium while being modulated with representations of the well logging signals. This modulation varies as a function of the rate of change of the well logging signals to produce an even density recording. Coding of the recorded lines or traces and the areas between selected traces can be accomplished. This coding of the lines is also varied in dependence on the well logging signal rate of change to produce a uniform coding presentation. Depth information can be recorded on the recording medium by writing depth numbers and depth lines on the record medium. Moreover, a section by section visual presentation of the data can be produced while it is being recorded.

Description

-Z91~3 This invention relates to methods and apparatus for processing well logging measurements for recording on a recording medium as a func~ion of the depth at which said measurements were obtained. The invention has special application to recordingof well logging data with a cathode ray tube recorder.
In producing well logging-measurements, a logging tool containing one or more exploring dPvices is lowered into a borehole drilled into the earth for measuring various pxoperties of the subsurface earth foxmations aajacent to a borehole, or properties of the borehole itself. Such measure-men~q are of considerable value in determining the presence and depth of hydrocarbon bearing zones that may exist in the `~
subsurface earth formations. !~ ~ ,,, "
It is desirable in may instances to provide one or more visible logs of the inves~igated subsurface phenomena ~ -at t~e well site within a relatively short ~ime after the log has been run. In other cases, it is desirable to transmit the well logging measurements to a remote location so as to enable processing of the data by a digital computer and thereby obtain valuable computed information. Such transmission~
can be undertaken while the investigating apparatus is being run through the borehole ~real time) ox at some later time as by recording the measurements on magnetic tape for subsequent transmission.
As is usually the case when such well logging data ,~
is transmitted to a remote location, the well logging measurements are converted into digital form for such trans-mission. To provide a meaningful visual record of such ~ransmitted well logging measurements, it is necessary to produce an analog type of presentation of the well logging measurements, usually in the form of recorded traces whos~
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~2473 positions on a recording medium are representative of the amplitudes well logging measurements versus depth.
When well logging measurements in digital form are transmitted from one location to another, it is sometimes the case that the transmitting tape includes data from two or more magnetic tapes which have been merged onto ~he transmitting tape~ Such merging of data produces a large number of measurement channels on a single tape. (Each channel corresp~nls to a separate informa~ion source.) To adequately produce an analog recording of such merged data puts harsh design criteria on a recorder for recroding all of this merged data in analog form. To record such merged well logging aata as well as unmerged data in the past, a galvanometer type of recorder has been used. In such a galvanometer recorder a plurality of galvanometer mirrors assume an angular orientation in proportion to the amplitude of the well logging measurement to be recorded such that light reflected off the mirror onto a nearby film .
will assume the proper position on the film. Unfortunately, a separate galvanometer mirror is required for each and every channel of data to be recorded. While there have been usually, though not always, a sufficient number of recording channels in currently used gal~anometer recorders to provide real time recording of well logging measurements (i_e~, recording of the measurements as they are derived from the investigating apparatus in the borehole), such is not always the case when recording merged data because of the large number of channels to be recoxdedO
It is, therefore, an object of the present invention to provide new and improved methods and apparatus for recording well logging data and, more particularly, for recording in a large number of channels of well logging data with one recording :
device. .

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~0~24~3 To accommodate such a large number of signal channels,~
a ca~hode ray tube recorder can be utilized for recording as many channels of data as desired. To accomplish this, the cathode ray tube beam is repetitively swept across the face of ¦ the cathode ray tube while being modulated as a function of the signals to be recorded. To accomplish this modulation, the ramp signal which causes the sweep of the beam across the face of the tube is compared with the well logying signals to be recorded and when the ramp signal amplitude equals the `~
10 well logging signal amplitude, the cathode ray tube beam is unblanked to produce a mark on the film. By so doing, as many well logging signals as desired can be recorded.
If the sweep rate is maintàined constant, the frequency of each well loggi~g signal to be recorded will affect the presentation on the film. Tha~ is to say, since a ~ark or image is placed on the film once per sweep for each well logging signal to be recorded, the spacing between such marks will be dependent on the rate of change of the well logging signal to be recorded. Thus, if a DC signal is being ~ recorded, ~he spacing between each mark will be much closer than for the case where a high fre~uency AC signal is being recorded. Without special provisions being made, the recorded high frequency signal will tend to look washed out when compared with the recorded DC signal.
It is, therefore, another object of the present invention to provide new and improved methods and apparatus for recording well logging signals wherein the frequency of the signals being recorded does not advexsely affect the visual presentation of such signals. ~
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When recording data from a plurality of channels on one portion of a recording medium, it is usually desirable to code one or more of the traces being recorded to enable easy .. . . . . .. . . .. .. ... . . . . . . . . .......................... . .. . ...... . . .
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SZ~L73 identification of the recorded traces corresponding to each measurement. Such coding usually takes the form of dotting or dashing, or both, one or more of the recorded traces.
~owever, variations in the frequency of the signals to be recorded will tend to vary ~he coding produced on the film.
For example, if the coding takes the form of dashing the recorded trace, the length of each dash (and space between dashes) will vary as a function of the frequency of the well logging signals.
It is, therefore, another object of ~he present invention to provide new and improved methods and apparatus for producing a uniform coding pattern regardless of the fre- -quency or rate of change of the signals to be recorded.
When recording a plurality of well logging measure- ~`
ments on one portion of a recording medium, the interval be-tween certain ones of the recorded traces is often indicative of certain subsurface characteristics. An example of this can be found in U.S. Patent No. 3,166,708 granted to M.L. Millican on January 19, 1965. When recording a plurality of well log-ging measurements on one portion of a recording medium, it be-comes difficult to visually identify the areas between selected ones of the recorded traces on the recording medium~ This is especially true when the recorded traces criSscroes back and ~orth. -It is, therefore, another object of the present invention to provide new and improved methods and apparatus for selectively coding the areas between recorded traces on a recording medium to provide easy identification of certain subsurface characteristics.
Many times, a particular formation parameter can be identified by the area between two recorded traces only when the trace corresponding to one well logging measurement is on . ~
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~L052~3 a particular side of the other trace, i.e.~ one signal amplitude is greater than the other. In this case, when the two traces crisscross, the relationship of the two recorded traces to one another will no longer be meaningful relative to the part-icular formation parameter.
It is another object of the present invention, therefore, to provide new and improved methods and apparatus for recording well logging data in such a manner that the area between selected traces can be readily indentified.
Along with recording the well logging measurements, it is desirable to provide visual indications on the recording medium of the depth levels from which the well logging measurements were obtained. When such well logging measurements are in digital form, the depth data is usually also in digital form thus requiring some processing of the digital depth data to enable depth numbers to be periodically recorded on the ;`
recording medium.
It is, therefore, another object of the present invention to provide new and improved methods and apparatus for processing digital depth data for recording on a recording medium.
While these recorded depth numbers provide easy identification of the absolute depth of the logs, it would be undesirable to record such depth numbers at frequent intervals. ;~
Such frequent recording of these depth numbers would undesirably~
clutter the log. However, it would be desirable to he able to identify the depth of these logs at more frequent intervals than would be provided by a relatively infrequent recording of the depth numbers. This can be accomplished by recording depth lines at selected intervals. In this connection, it would be desirable to provide readily indentifiable indications on the recording medium of selected increments of depth.

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' ~S2473 It is, therefore, still another object of the present invention to provide new and improved methods and apparatus for recording depth lines in a manner to provide easy identification of different depth increments.
When using a cathode ray tube for recording purposes, it would be desirable to monitor the beam current of the cathode ray tuhe and maintain this current at a relatively constant level so as to produce a relatively constant exposure on the film. However~ since the beam is being modulated, i.eO, unblanked at unpredictable positions of its sweep across the face of the CRT, it is difficult to know just when to measure the beam current. `
It is, therefore, yet another object of the present invention to provide new and improved methods and apparatus for measuring the beam current of a cathode ray tube for purposes of maintaining a relatively constant film exposure.
When recording well logging data, a recording -mechanism exposes selected portions of a film in accordance with the information to be recoxded. The exposed film must then be developed, and dried, before one is able to inspect the log. It would, however, be desirable to be able to inspect the log at ths same time the film is being exposed, which i5 an impossibility with present recording devices.
It is, therefore, still another object of the present invention to provide new and improved methods and apparatus ~ ;
which enable immediate inspection of the data being recorded. -In accordance with the recording methods and apparatus of the present invention, well logging signals, either in analog or digital form, are derived from either an exploring device in a borehole or from digital processing equipment such as a digital tape recorder or telemetry equipment for application to the recorder of the present invention. In a .. ..
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~ 52~73 desirable fonm, this recording equipment comprises a cathode ray tube recorder which, in response to a digitally generated sweep signal, repetitively sweaps a beam across a recording medium which is moved past this face at a rate dependent on the depth at which the signals to be recorded were derived.
The well logging signals are processed and then used to modulate the beam intensity.
To produce a constant density trace on the record medium in accordance with a feature of the invention, the length of the trace recorded on the record medium for each sweep of the beam is varied as a function of the rate of change of the well logging signal. This is accomplished by comparing the sweep signal (whose amplitude is representative of the position of the beam on the record medium) with delayed and undelayed versions of the well ~logging signal and generating a writing signal wbose pulse width is representative of the rate of change of the well logging signal. This writing signal can be used to modulate the beam.
The recorded data can be coded to distinguish the recorded signals (called logs) from one another (called line coding) and to distinguish areas between logs from one another ;
(called area coding). Line coding is accomplished by selec~ively inhibiting at least one portion of a writing signal in dependence on the rate of change of the well logging signal to be recorded. Area coding is accomplished by generating a coding pattern signal and modulating the beam with this pattern signal to thereby produce the pattern on the record medium. Conditional coding is accomplished by modulating the beam intensity as a function of this coding pat~ern signal only when two well logging signals assume a predetermined relationship to one another.
The beam current of the cathode ray tube can be ~ 5i2~
controlled by modulating the beam intensity with a constant amplitude signal at a predetermined time during each sweep of ~
the beam. The beam current can then be measured at the proper "
time during each sweep and this measured value used to adjust the beam current to a desired level.
Depth information can be recorded in accordance with another feature of the invention. This can be accomplished by writing each digit of a depth number in side by side positions on record medium and/or by writing a prescribed number of lines on the record medium for given incremental `~
change in depth. Digital depth data from suitable digital processing equipment can be used for these purposes.
In accordance with still another feature of the invention, the well logging signals are displayed a depth -;
section at a time. To accomplish this, a CRT beam is swept in one direction as a function of depth while it is at the same time repetitively swept in a transverse direction thereto.
The beam is modulated with representations of the well logging signals.
More particularly, there is provided: a method `
of recording or displaying data signals of the type represent-ing well logging data as a function of depth on a recording -or displaying medium wherein at least one writing signal is pxoduced in response to at least one data signal and com-prising the steps of directing energy at said record or display medium along a line substantially transverse to said medium to place images on said medium generating a coding pattern signal and combining said at least one writing signal with said coding pattern signal to control the level of said energy to produce a coding pattern between selected boundaries on said recording or displaying medium, at least one boundary being representative of said at least one data signal.
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~ais2~73 There is also provided: apparatus for recording or displaying well logging data comprising:
(a) means for producing at least one well logging signal representative of at least one subsurface characteristic at various depth levels in a borehole;
(b) a recording or displaying medium; `~
(c) means adapted for repetitively sweeping energy -across said medium;
(d) means responsive to said signal for producing .
writing signals;
(e) means for generating a coding pattern signal; and (E) means responsive to said coding pattern and writing signals for modulating said energy to produce a coding pattern on said medium between the recorded traces resulting from said writing signal and another selected location.
In the apparatus in the preceding paragraph the means for producing at least one well logging signal repre-sentative of a subsurface characteristic at various depth levels in a borehole produces at least two such signals;
said signal responsive means being responsive to selecte`d samples of said well logging signals for producing at least two writing signals; and said means responsive to said coding pattern and writing signals produces a coding pattern between -boundaries representative of said at least two writing signals.
For a better understanding of the present invention, ~-~
together with other and furtherobjects thereoE, reference is had to the following description taken in connection with the accompanying drawings, the scope of the invention being pointed out in the appended Claims.
Referring to the drawings:
FIGURE 1 is a block diagram representation of one embodiment of well logging data recording apparatus '`

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~ i2~73 constructed in accordance with the present invention;
FIGURE lA shows a portion of the FIGURE 1 system in greater detail; .
FIGURES 2A-2G are waveform diagrams useful in explaining certain features of the Figure 1 system;
FIGURE 3 illustrates an example of a recording medium on which scale lines have been recorded when utilizing`:
the Figure 1 system; -~
. ,: . ., FIGURES 4A and 4B show certain portions of the Figure 1 system in greater detail and will hereinafter be ~
referred to simply as Figure 4; :
FIGURES 5A-5K, 6A-6F, and 7A-7F are waveform diagrams useful in explaining the operation of the circuitry-: :
of Figure 4; ~ ~
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-~ 5~3 FIGURE 8 is an example of a xecording medium on which depth lines have been recorded through utilization of the Figure 4 circuitry;
FIGURE 9 is an example of a recording medium on which both scale lines and depth lines have been recorded;
FIGURE 10 illustrates a portion of the Figure 1 ~ :
system in greater detail;
FIGURES llA-llE are waveform diagrams useful in explaining the operation o circuitry of Figure 10;
FIGU~E 12 is an example of a log or record produced : ~
when utilizing the apparatus of Figure 10; - :
FIGURE 13 is a more detailed representation of still another portion of the Figure 1 system;
FIGURES 14A, 14B and 14C show a more detailed representation of still another portion of the Figure 1 system and will be hereinafter referred to simply as Figure 14;
~ IGURES 15A-15L illustrate examples or recordings :. .
produced through utilization of the apparatus of Figure 14; -.~
FIGURES 16A-16G illustrate wa~eform diagrams useful -~ ~:
in explaining the operation o~ the apparatus of Figure 14;
~ IGURES 17A and 17B show still other portions of the Figure 1 system in greater detail and will be hereinafter referred to as Fiyure 17;
FIGURE 18 shows a well tool in a borehole along with recording apparatus cons~ructed in accord~nce with the present invention; and FIGURE 19 shows still another embodiment of recording apparatus constructed in accordance with the present invention.
Now referring to Figure 1, a digital information source 20 produces output signals which are utilized by the recording apparatus of the present invention to provide recordings o~ such signals. This in~ormation source 20 can --11~

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1~)5i~2473 ~ ~
take th,e form of a digital telemetry transmitter receiver such as the system shown in Miller et al V.S. Patent 3,599,156 of ';~
August 10, 1971. For presen~ purposes, it will be assumed that the information source 20 takes the form of the digital telemetry system shown in the said Miller et al UOS. Patent ';~ ;, 3,599,156.
The telemetry system described in this copending '~
Miller et al application is a tape-to-~ape synchronous digital transmission system wherein data read from a tape at one , ~' remote location is transmitted in serial form to a telemetry , receiver at another remote location and written on tape at that remote location. At both the transmitting and receiving locations, the telemetry equipment includes playback circuits which convert the serial digital data to analog output signals ', which are representative of the digital data. Additionally ',,~
this telemetry equipment includes provisions for playing back a tape without transmission to con~ert the digital data on tape " , to parallel analog signals. These parallel analog signals are '~, -outputed from the telemetry equipment on the cond~ctors 21.
The channels 1~ 2, 3 ..... n designations on individual ones of these conductors indicates the channel num~ers of the data being outputed from the telemetry equipment 20. Each channel corresponds to a diferent information source or well logging measurement. The outputed data can correspond to transmitted or received data or it can take the orm o~ data played back ' from a tape without a simultaneous transmissio~,. ~- - ' These outputed well logging measurements are applied' to a plurality of parallel low pass filters Z2 which operate to filter out any transients caused by the commutating operation within the telemetry equipment 20. The filtered well logging signals are then applied to a plurality of parallel pulse positions and pulse width modulators 23 which .. . . .
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~L~5~73 indi~idually operate to produce wri~ing signals for application -to subsequent circuits for further processing.
These individual modulators operate to compare a sawtooth sweep signal from a sweep circuit 24 with the-individual well logging signals and produce writing signals when the amplitudes of the two compared signals are sub-stantially equal. In producing these writing signals, the individual modulators operate to compensate for vaxiations in the frequency or rate of ch~nge of the individual well logging signals. ~ow this is accomplished will be described in detail laterD ;
The modulated signals are then applied to "parallel line coding circuits" 45 where they are selectively coded so that, when recorded on film or the like, the recorded traces for each channel can be readily identified. The modulated signals are also applied to area coding circuits 48 via an `
area coding card reader 47. The area coding circuits 48 `~
operate to generate area coding patterns which are recorded between selected traces on the recording medium ~e.g., film).
The area coding card reader 47 selects the patterns and the signal channels or this coding operation~ Both the line and area coded signals are combined in a "combining and logic c~rcuit" 42, as are othex signals to be discussed later. The combined signals are applied to a"CRT brightness control circuit" 50 for application to the brigh~ness control grids of the cathode ray tube 25.
The sweep signal generated by the sweep circuit 24 is applied via a "CRT horizontal deflection circuit" 34 to the horizontal sweep coils of the tube 25 for repetitively sweeping the beam across the face of tube 25. The beam is modulated by the signals from tne CRT brightness control circuits S0 to record traces o~ a rPcording medium (film) 36. Desirably, ~5;~73 the cathode ray tube 25 is of the fiber optic type in that ~`
it has a fiber optic face plate for bringing about superior resolution of the "spot" (beam striking the face) on the ~`~
recording medium 36.

The recording medium 36 is moved past the face of the tube 25 at a constant rate by a constan-t speed motor 37 which moves the film at a rate determined by the transmission :
rate of telemetry equipment 20. If desired, the mo~or 35 :
could be synchronized by the telemetry equipment 20.
Before proceeding with a detailed discussion of how -~
the writing signals are processed for application to a CRT
recorder, it would first be desirable to discuss the operation of the sweep circuit ~4 portion of the present invention in det~il. This sweep circuit 24 operates to periodically .
gen~rate pulses at a fixed freguency, count these pulses, and produce a sweep signal for application to a cathode ray tube :-and provide ~iscrete digital siynals for use by other circuits .~ :
in the Figure 1 system. :
A pulse generator circuit 26 utilizes the 60 Hertz power line for generating pulses a frequency of 120 Hertz. . i .
(See Figure 2A.) The generator 26 can take the form of an overdriven amplifier, clipping circuit, and monostable multi-vibrator operating in conjunction to generate a pulse for each zero crossing of the 60 Hert~ signal. Each pulse ;
produced by the generator 2S sets a sweep control flip-flop 27 which, when s~t, enables an AND gate 28 to pass high frequency pulses generated by a high frequency clock 29. (See Figures 2B and 2C.) The pulses from the AND gate 28 designated CL, are divided by two by a flip-flop 30 and applied to the count input of a binary counter 31. As will be seen later, the numerical state of the binary counter 31 corresponds to the position o~ the beam on the face of a cathode ray tube.

~ . . .

1~5~473 The binary counter 31 output is applied to a binary to analog converter 32 which produces an analog voltage whoe magnitude increases in accordance with the increase of the -count state of the binary counter 31. Thus, as more and more clock pulses are applied to the counter 31, the output voltage of the binary analog converter 32 will correspondingly increase. This output signal from the converter 32 is designated the'sweep signal" and is shown in Figure 2D.
This sweep signal is applied to the modulators 23 as well as to CRT horizontal deflection ~ircuits '34 which process the sweep signal in a manner to produce a linear sweep ~ersus time of the cathode ray tube beam across the face thereof. Thus, the sweep signal can he referred to as a sweep position signal.
An '!end of sweep matrix circuit" 35 responds to a selected numerical count of binary counter 31 to produce a reset pulse for re&etting the sweep conkrol flip-flop 27.
(See Figure 2E.) This sweep reset pulse is also applied to various other circuits in the Figure 1 system f~r purposes to , :
be described lateri The output signals from each stage of the binary counter 31 are also applied'to a scale line circuit 37 which, in response to selected count sequences of the binary counter 31, generates scale line signals used for writing scale lines on the recording medium 36. To accomplish this, the output signals from binary counter 31 are applied to a scale grid card reader 38 which'selects certain numerical outputs of the :
binary counter 31 for application to one of a pair of one-shots 39 and 40. The one-shot 39 produces pulses having a pulse width of time duration tl and one-shot 40 produces pul~es having a puls2 width of time duration tl + t2. The output of one-shots 39 and 40 are combined in an OR gate 41 for application to combining and logic circuits 42. Figure 2F

l~S2473 shows the resulting scale grid pulses.
The combining and logic circuit 42 processes these pulses from one-shots 39 and 40 to produce scale lines on the r~cording medium 36. The pulse width of the pulses from one-shots 39 and 40 determine the length of the trace produced on the recording medium 36 as the beam sweeps transversely across the recording medium 36. These traces are shown in Figure 2F.
Since the recording medium is moving in a direction perpendic-ular to the direction of this sweep, the writing time will determine the width of the line produced on the recording medium as the beam is repetitively swept thereacross. The card reader 38 enables any scale line pattern desired to be produced by ;
merely inserting the appropriate card therein.
The scale line circuit 37 also includes an "initial scale line one-shot" 43 which operates in response to the leading or rising edge of the sweep control signal flip-flop 27 output signal to generate an "initial scale line pulse"
for applicaticn to the OR g~te 41 and separately to the combining circuits 42, as well as to other circuits to be described later. Since, as seen in Figure 2~, the sweep contxol signal rises at the initiation of the s~eep signal of Figure 2D, the one-shot 43 will operate to generate a pulse at the beginning of each sweep, which pulse is used o produce an initial scale line on the recording medium. The reason for this separate treatment of the initial scale line will be described later.
The writing signals from modulators 23 are individually applied to separate ones of a plurality of parallel line coding circuits 45 which operate to code the traces which are recorded on ~he recording medium 36. As will be explained in more detail later, the coding circuits 45 operate to inhibit selected portions of ~he writing signals . . . . .
, , ~5;~:~'73 to accomplish this coding operation. The coding circuits 45 also operate in response to the rate of change of the well logging signals to vary the coding operation as a function of this rate of change to enable uniform line coding regardless of the rate of change of the well logging signals. To allow selection of the particular type o~ coding to be applied to -the signals for each channel, the line coding card reader 46 instructs the line coding circuits 45 to apply selected codes to signals from the different channels.
The writing signals from ~odulator 23 are also applied to an area coding card reader 47 which selects individual ones of the writing signals from modulators 23 for application to individual coding circuits of the area coding ; circuits 48. The area coding circuits 48 include a plurality of pattern generators which operate to individually produce any one of twelve patterns on the recording medium 36;
Examples of these patterns are shown in Figures 15A~15L.
These patterns can indicate such subsurface con tituents as oil, gas, sand, porosity, water, limestone, etc.
As discussed earlier, it is usually the case that the area between two recorded traces indicates the amount of a particular subsurface constituent only when one of the traces is on one or the other side of the other traae on the recording medium. ~o enable the area coding circuits 48 to ge~erate patterns only under the proper conditionS~ the area coding card reader 47 causes ~he card reader 47 to select certain ones of the writing signals as "start" signals and certain ones as "stop"signals. The start signals will signal the circuits 48 to begin producing the area coding pattern and the stop signals will cause the pattern to terminate- If the selected start-stop signals are reversed, no pattern will be j~
produced.

~L~5;~4~73 Addi~ionally, the line coded writing signals are :~
appliad to a "trace intensifier card reader" 49 which, in reponse to a selected card placed therein, selects certain ones ~`
of the line c~ded writing signals for application to a special input channel of the combining and logic circuit 42. The .;
circuit 42 operates to boost the amplitude of these selected si~nals to thereby intensify the recorded trace for just these signals. The combining circuits 42,.among ~ther things, . :-combines all of the line coded and area coded signals and separately combines the trace intensified signals for all ........ :
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channels for application to the CRT brightness control circuits 50. The combining circuits 42, in addition to combining these ..:
signals, also includes suitable logic circuits which operate to give preferential treatment to certain ones of the writing .:.
signals applied thereto for purposes to be explained later~
The CRT brightness control circuits operate to combine the line and area coded writing signals, the trace -.
intensified signals and scale line signals (as well as depth :;
line signals - to be discussed later) and produce signals for modulating a grid~of the cathode ray tube 25. The brightness contxol circuits 50 also operate to monitor and control the beam current prQduced by the cathode ray tube 25.
As discussed earlier, the cathode ray tube is modulated by the writing signals produced from well logging measurements at random time inter~als, thus making it very ::
difficult to properly monitor the beam current for control ;
purposes. To circumvent~this problem, in accordance with an important feature of the present invention, the initial scale line pulse from scale line circuit 37 causes the cathode ray .
tube beam to be unblanked a specified amount and at a specified ~
t~me period during each sweep. This specified time is the .
beginning of each sweep. To this end, the initial scale line : . -,'. . , ,~ ' .

\
35;~473 pulse from the scale line circuit 37 is applied to the CRT
brightness control circuits S0 to inform the circuits as to `~
the time when the initial scale line is being written. As will be explained in greater detail later, the CRT brightness ~;
control circuits S0 operate in response to this initial scale line pulse to sample the beam current and appropriately adjust it, if necessary. By so doing, the beam current will be maintained at the desired level.

: .
The system of Figure 1 also operates in accordance with other features of the present invention to record depth infonma~ion, e.gO, depth lines and depth numbers on the recording medium 36. To accomplish this, the initial depth at which well logging measurements are derived i5 set into depth determination circuits 60 by a plurality of initial depth preset switche~ 61. Data from the telemetry transmitter or receiver is thereafter utilized to continuously update the depth determination circuits 60. The depth determination circuits 60 continually provides data for a dep~h display i unit 62 so that a numerical representation of the depth of the well logging signals outputed from the telemetry transmitter or receiver 20 can be viewed at all times.
To update the depth determination circuit 60, pulse code modulated data from the telemetry unit 20 is applied to the depth determination circuit 60 fox entry into an appropriate register. ~he telemetry equipment 20 also supplies shift ; pulses and a shift pulse window to the depth determination 60 to enable the pulse code modulation data to be shifted into the register at only the time period when a depth word is ; being transmltted or received. The-shift pulses are applied to this entry register under control of the shift pulse window, the shift pulse window acting to insure that only the necessary number of shift pulses are actually applied to this --19_ iz4'73 entry register. The telemetry equipment 20 causes a depth shift command pulse to be applied to the depth determination circuits 60 to insure that only depth words are entered into this entry register. The depth data in this entry register . . .. .. . .
is then shifted to another register by a gate control pulse from the telemetry equipment 20 after the depth word has been entered into this entry register. How the depth determination circuits 60 utilize these signals from the telemetry equipment 20 will be described in detail later.
As mentioned earlier, the telemetry equipment 20 ;~ is described in the said Miller et al UOS. Patent 3,599,156.
In this United States Patent the pulse code modulated data is derived from the wiper arm of a four position switch 70A in Figure 15C of that application. The shift pulses are derived from the output of an AND gate 205 in Figure 15A of the co-;.
pending Miller et al appIication and are designated "shi~t 14"
therein. The shift pulse window is deri*ed rom a one-shot 187 in Figure 15A of the copending Nillet et al application ,~ . . .
and is designated "tape write and depth display window"
therein. The depth shift command pulse is derived from the wiper arm of a four position swit~h 70E in Figure 15A of the said Miller et al U.S. Patent 3,599,156 and is designated "command shift depth display" therein! The gate control pul~e is derived from a one-shot 188 in Figure 15A of the said Miller et al U.S. Patent 3,599,156 and is designated "X4"
therein.
It is to be understood that the telemetry apparatus for producing these above-described signals does not comprise part of the present invention. Furthermore, it is to be understood that any information source could be utilized as the input ~o the recording apparatus of the present invention ; and the invention is thus not limited to recording data from -2~ ~
., .

S~47~
the telemetry equipment described in the copending Miller et al application.
The depth determination circuits 60 supply data to a depth interval detector 63 which operates to generate ~.
signals representative of 2', 10', 50' and 100' depth intervals.
The 2' t 10 ~ and 50' depth interval signals are applied to a "depth line genera~or" 64 which operates to generate "depth :
line writing signals n for application to the combining and logic circuits 42 for subsequent recording. The depth line generator 64 opera~es to generate one line for every 2 foot depth interval, two lines for every 10 foot interval and four lines for evexy 50 foot interval. The depth determination circuit.60 also supplies data to a "digit selector circuit"
.` 65 which processes the depth data and causes a numerical display of the depth number by energizing a cathode ray tube .
; numerical display unit 67 via a "depth driving CRT circu _"
66. The display unit 67 ~s positioned relative to the re-cording medium 36 so as to record numerical representations : of the depth numbers on the recording medium 36. The digit .: 20 selector circuits 65 process the depth data from the depth determination circuits 60 so that depth numbers will be :~ printed on the re¢ording medium 36 when the last two digits of the depth numbers are 96, 98, 00, 02, a~d 04. Thus, for .
example, a digit of a depth number will be recorded at each of .
2196 ft., 2198 ft., 2200 ft., 2202 ft., and 2204 ft~ By so doing, the depth number will appear sideways on the record medium to minimize the width of the depth track.
The hundred foot depth interval signals fxom the depth interval detector 63 are applied to a sawtooth generator 70 which operates to generate a timing signal having a time period corresponding to 100 feet of data generated from the telemetry equipment 20. This 100 ft. sawtooth signal is ;.

. ,, . .... , .. . . ., . , . . .. ., , .. . . . . ... , .. . -- , .

~L~52473 ~
: applied to a vertical deflection amplifier 71 which drives the vertical deflection coil of a storage cathode ray tube - :
72. The horizontal sweep signal`from the ~weep circuit 24 ~.:
; is utilized to energize the horizontal sweep coil of the storage cathode ray tube 72 via a horizontal deflection amplifier 73. The CRT brightness control circuits 50 supply the combined writing signals to the stor7ge cathode ray tube 72 to modulate the beam intensity thereof.
By this arrangement, in accordance with another `.
feature of ~he present invention, the storage cathode ray ; tube 72 will provide-a visual display of up to lO0 feet of recorded data to thereby enable one to visually determine what data has been recorded on the recording medium 36. The : phosphor of the storage CRT 72 is erased at the end of each lO0 ft. interval.
. .
Now turning to Figure 4, there is shown the depth determination circuits t initial depth preset switches, digit ;
selector circuits, depth interval detector and depth line generator of ~igure 1 in greater detail. First, concerning the initial depth preset switches 61, five decade switches 80, 81, 82, 83, and 84 are set in accordance with the initial : depth o~ the data which is being transmi~ted or received by the telemet~y equipment 20. The decade switch 80 corresponds to units of feet, the decade switch 81 to tens of feet, switch 82 to hundred~ of feet, switch 83 to thousands of feet, and the switch 84 to tens of thousands of feet. The ten contacts -~
of each decade switch are connected to individual decimal to binary coded decimal converters 85 which operate to convert . the decimal number from each decade switch to a binary coded decimal number-The binary coded decimal numbers corresponding to the tens, hundreds, and thousands foot switches are applied ;~

- . ' ' ~ . .,, ' ' ', ,, ': . ~
.. .. . ~, . .
: .

~S~2~73 i to the tens, hundreds, and thousands foot positions of a five decade depth memory regis~er 86 via OR gates 87. The units and tens of thousands foot ~inary coded decimal numbers are applied directly to the corresponding portions of ~he register 86. ~:
To set the initial depth number into the register 86, a switch 87 is momentarily depressed so as to apply a DC voltage to the wiper arms of the five decade switches 80- :
84. Once the switch R7 is depressed, the memory register 86 will have stored therein the initial depth of the measurements to be received from the telemetry equipment 20.
The depth memory register 86 is then continually updated as data is transmitted, received or played back by the telemetry equipment 20. To accomplish this, the pulse code modulated data from the telemetry equipment 20 is entered into a three-decade shift register 90. As discussed in the said Miller et-al U.S. Patent 3,599,156, depth words are transmitted every ten feet. Thus,.whenever a depth word is i e~tered into the depth register 90, it can be assumed that the lowest order digit will always be zero. ...
Since the PCM data conductor from telemetry equip~ .
. ment 20 has data therein continuously, the depth entry register 90 is activated only when a depth word is being transmitted or received. ro accomplish this, the shift puIses and shift pulse window (which corresponds in time to the generation of ; the shift pulses) and the depth shi~t command pulse from the telemetry equipment 20 are combined in an AND gate 91. The resulting gated shift pulses from AND gate 91 are utilized to shift the contents of the depkh register 90.only when depth `
30 words are being transmitted,. received, or played ~ack. By .
this means, only depth words will be e~tered into the depth register 90. .~

.: .
-23- :~
~' :

' ~

1~5;~ 3 After depth has been entered into the register 90, a plurality of depth memory control ga~es 92 are energized by the gate control pulse from the telemetry e~uipment 20 to transfer the data in the depth register 90 to the tens, hundreds, and ~housands foot portions of the depth memory register 86 via the OR gates 87. Thus, the tens,hundreds, and thousands portion of the memory register 86 will be con-tinuously updated while data is processed by the telemetry ; equipment 20. ;
To update the units foot portion of the depth memory register 86, the shift pulse window pulses from the telemetry equipment 20 are divided by two by a flip-flop 93 and then . .
applied to the count input of the unit foot position of the register 86. As discussed in the said Miller et al U.S. Patent 3,599,156, the shift pulse window pulses are generated once per 5iX inches of depth. Thus, the ~nits foot portions of the depth memory register 86 will be updated at one foot intervals.
` The register ~6 counts down to correspond with the telemetry ;i operation. (Boreholes are logged from bottom to top and thus 20 the actual depth footage decreases.) The contents of the depth memory register 86 are applied in parallel fashion to the depth display unit 62 such that a visual numerical display Or the dapth of th~ dàta being transmitted, received or played back by the telemetry equipment 20 can be obtained at all ~imes. The c~ntents of the depth memory register 86 are also applied to the digit selector circuits 65, which as discussed earlier, operate to select those depth numbers whose last two digits are 96, 98, 00, ~2, and 04 for application to the cathode ray tube n~merical display device 67.
To accomplish this, the binary coded decimal outpu~
signals from the units and tens decade units of the depth - ' ' '~

, ' ' ' '' ' .': : ' . . ' .

~, memory xegister 86 are applied to a pai-r of binary coded "i decimal to decLmal conver~ers 95 and 96 respectively. ~,he count sequences for the combination of converters 95 and 96 are shown in Figure 5A. An AND gate 97 is responsive to the zero digit of the converter 96 and the No. 4 digit of the :; converter 95 for producing the pulse of Pigure 5B for setting a flip-flop 98. When set, the flip-flop 98, whose normal output is shown in Figure 5C~ enables an AND gate 99 to pass a two foot depth signal from the depth interval detectors 63. ~;
The gated two foot depth signal is shown in Figure 5D. (This ., two foot depth signal is obtained by dividing the one foot depth signal from the flip-flop 93 by two with a divide by two flip-flop 100 within the depth interval detector 63.) Every two feet the leading edge of the gated two foot signal from AND gate 99 advances a binary counter 101 and energi,ze~ '' a one shot 102. The binary counter 101 count sequences are ,, shown in Figure 5E and the one shot 102 output pulses are shown in Figure 5G., The three stages of the binary counter 101 are connected to a binary to decimal converter 103 which produces an output signal on one of five output conductors during the ~'~
:.
first five count sequences of the binary counter lOlo As stated earlier, depth numbers are printed on the ,~

'~.; record medium 36 sequentially in reverse order as the record ' medium moves past the depth number printing CRT 67 (see ,~. Figure 1) and since depth numbers are printed every 100 feet, , ~ .

~', the first two printed digits will be zero~ Thus, the first '' and second output sequences from converter 103 are combined ,:

. in an OR gate 112 and applied to the zero input position of ' ,i the CRT numerical display unit 67 via an AND gate 113. The AND gate 113 is enabled by the output pulse from one-shot 102 ' to cause the CRT 67 ~o be flashed at the proper time and for : the proper time duration to enable an appropriate exposure time :::
,:
. . .

!. . . ; ., - on the film record medium 36.
~¦ The hundreds, ~housands, and ten thousands binary coded decimal signals from the depth memory register 86 are `~
¦ applied to three parallel binary coded decimal to decimal ¦ converters 104. The conjunctive combination of the thirdsequence output signal from the binary decimal to decimal ~
converter 103 and the pulse from the one-shot 102 energizes ~ :
ten individual parallel gates 105 by way of an AND gate 106.
When energized, the gates 105 connect the ten output conductors from the hundreds foot portion of the binary coded decimal to decimal converter 104 to ten OR gates 107. The enabling ~`
pulse from AND gate 106 is shown in Figure 5H.
The number 4 sequence output from the binary to decimal converter 103 and the pulse from one-shot 102 are combined in an AND gate 107 for energizing 10 parallel gate circuits 108. When energized, the parallel AND gates 108 connect the ten output conductors from the thousands foot ~;
. portion of the binary coded decimal to decimal conv~rter 104 to individual ones of the OR gates 107. The enabling pulse from AND gate 107 is shown in Figure 51.
. In like fashion, the No. 5 sequence output from the binary to decimal converter 103-is combined with the output pulses from one-shot 102 in an AND gate 109 for energizing ;~
the parallel AND gates 11~ during the fifth sequence of the :
binary coun~er 101. (See Figure S~.) When energized, the parallel AND gates 110 connect the ten output conductors . from the ten thousands foot portion of the binaxy coded decimal to decimal converter 104 to indi~idual ones of the OR .~. .
gates 107. The output from the 10 OR gates 107 are connected : :
to individual ones of the ten input terminals of the CRT
numerical display unit 67. The leading edge of the No. 5 : sequ~nce output signal resets the flip-flop 98 and thus the ':
:~S2~
AND gate 9g to prevent the counter 101 from being advanced beyond sequence No. 5.
To rese~ ~he binary coun~er 101, an AND gate 111 is responsive to the No. 2 output of the units foot position of the binary coded decimal to decimal converter 95 and the nine digit output of the tens foot output position of the binary coded decImal to decimal converter 96 for resetting the binary counter 101 whenever the tens and units digits of the depth number are 92.

Summarizing the operation of the digit selector ~:
circuit 65, whenever the last two digits of the depth number are ~4 as determined by the AND gate 97, the flip-flop 98 is set to enable binary counter lQl to count the rising edges of the two foot depth signal from ~he depth interval detector 63, as seen by inspecting Figures 5A-5D. As seen in Figure 5E, the ;~:
binary counter 101 counts five rising edges of the two foot ::
depth signal and then resets itself when the last two digits of the depth number are 92.
During thP first two sequences, the binary to decimal conver~er 103 energizes the ~Izero~ input of the nu-merical display unit 67 by way of the OR gate 111. During ~:
the third se~uence, i.e., at a depth whose last two disits are 00, the number for the hundreds foot digit is gated by the parallel gates 105 to the proper input terminal of the numerical display unit 67 by way of the OR gates 107. Thus, for example, i~ the hundrsdths foot number is 6, the numerical display unit 67 will display the number 6 during sequence 3.
During sequences 4 and 5 the thousandths and ten-thousandths foot numbers are likewise gated to the proper input terminals : :
of the numerical display unit 67. `:

At the beginning of sequence 5, the flip-flop 98 is reset to thereby disable advancement of the binary counter 101.

.. ..... .. .. .... ...... .......... . . .................. .
.: , , :' , " ':. :, ~ ' ' , ' ~ ~05~7~

The binary counter 101 is then reset a~er the entire number ¦ has been printed by the pulse from AND gate 111.
Taking an example of this operation assume that the number to be printed is 5100 feet. At 5104 feet, the flip-flop 98 will be set and the binary counter 101 will advance to its first count sequence thus enabling the AND
gate 113 via OR gate 112. The pulse from on~ shot 102 then ~-energizes the zero digit of the display unit 67 and a zero ; is printed at 5104 feet. Next, at 5102 feet the binary counter 101 advances to its number two count sequence and through the same operation a zero is again prin~ed. At 5100 feet the binary counter 101 advances to its number three count sequence, thus enabling the AND gate 10~ to pass the pulse ; from one shot 102 to the parallel gates 105. The hundredths - foot portion of binary coded decimal to decimal converter 104 will, at this time, be generating an output signal on the number five output conductor such tha~ when the gates 105 are energized, the number five digit of the display unit 67 will be energized. Then at the number four sequence, the number ~ive ~utput signal from the thousandths foot portion of converter 104 will energize the number five digit of the display unit 67. During the fifth sequence, the zero digit o the display unit 67 will be flashed. Then at 4992 feet, a safe time ater the entire depth n~mber has been printed, the system will be reset in readiness for the same operation to occur at 5004 feet for printing the depth number 5000.
; Now concerning the depth interval detector 63, it operates in reponse to data from the depth register 90 and the divide by two flip-flop 93 to generate 2, 10, 50 and 100 foot signals. How the two fDot signal is generated has -~
already been discussed. To generate the 50 foot signal, a -matrix circuit 120 is responsive to the tens foot portion of the ~ -' -~8-,, - ;

~S~ 73 depth register 90 to generate an ou~put pulse every 50 feet.
...
To generate the 100 foot signal, a matri~ circuit 121 is responsive to the hundreds foot portion of the depth register 90 to generate a pulse every 100 feet. The ten foot depth pulse~ are obtained directly from the depth shift command output of the telemetry equipment 20 since, as discussed earlier, a depth word is transmitted every ten feet by the telemetry e~uipment described in the copending Miller et al application. ' : 10 The hundreds foot depth pulses from the detector 63 are applied to the hundred foot sawtooth generator 70 of Figure 1 to enable the hundred foot depth sweep for the storage cathode ray tube 72. :
The depth line generator 64 operates in response to ~:
the 2, 10, and 50 foot depth sisnals from the depth interval ..
detector 63 to generate ~ignals which causes a line to be written on the recording medium every two feet, two lines to .
be written every ten feet, and four lines to be written e~ery `
fifty feet. To accomplish this, referring to ~igures 4 and :`
6A-6~ in conjunction, and first concerning the two foot poxtion of the depth line generator 64, the leading edges of ~he two ``~`
foot depth signals, shown in Figure 6A, set a flip-~lop 125 ; which when set, enables an AND gate 126~ The normal outpu~ of flip-flop 125 i5 shown in Figure 6C. When enabled, the AND :.
gate 126 passes the sweep reset pulses, shown in Figure 6B, to the set inpu~ of a flip-flop 127. The resulting gated sweep reset pulses a.re shown in Figure 6D~ The flip-flop 127 is set on the trailing or falling edge of each gated sweep reset .
pulse of Figure 6D. The trailing edge of each sweep xeset pulse also resets the flip-flop 125 via a NAND gate 128 .

which inverts the output pulses from AND gate 126 to enable ;
the pulse rising edges to reset flip-~lop 125.

.

,' ' ` . .` ;"` ' ~'. ' : ` . . ~
'' ` ' . ~ ` :

` 1~5;247~
The normal output of flip-flop 127, shown in Figure 6E,is applied to an OR gate 130. The output signals from OR gate 130 constitute the dep~h line signals which are applied ~ to combining and logic circuit 42 for eventually causing one I line to be swept transversely across the recording medium 25 every two feet. To insure that only one depth line is printed every two feet, the normal output of the flip-flop 127 enables NAND gate 131 to pass the sweep reset pulses to the : reset input of the flip-flop 127 after one sweep of a depth ~-line has been completed. The ou~put signals from NAND gate .' . ~.
I 131 is sh~wn in Figure 6F. -~
To generate two such depth lines every ten feet is I the unc~ion of the ten foot depth line generator 133 of the depth line generator circuitry 64. The ten foot depth line 3 generator 133 operates in an identical fashion as the two foot dep~h line generator 124 except that a divide by two ! flip-flop 134 prevents the control flip-flop corresponding to `
. ;. .. .
flip-flop 127 of the two foot circDit 124 from being reset `~ until two sweeps have been completed and the two depth line sweeps are initiated by the ten foo~ signal from depth interval detector 63. Thus, during the time ~hat it takes the cathode ray tube 25 ~o complete two sweeps, the output of the OR gate 130 is maintained at the "one" level by the ten foot line generator 133 to thereby produce two depth lines on the record medium every ten feet.
To generate four dePth lines every 50 feet, a 50 foot depth line gen~rator 135 responds to the fifty foot depth pulses from the depth interval detector 63. The fifty foot depth line generator 135 operates in an identical fashion with the two foot and ten foot depth line generators 124 and 133 except that a divide by four circuit 136 prevents the system from resetting itself until four sweeps have been completed.
.,' .

. .. , ., .. : , 1 ~05;2473 These elements in the 10 foot and 50 foot depth line generators 133 and 135 which are identical in operation with elements in ~`
the two foot depth line generator 124 a~e designated th~ same except for the addition of a letter a after the numbers for the ten foot depth line generator 133 and the addition of a letter '~`
b for the fifty foot depth line generator 135.
Figure 8 is an example of a recording medium with the depth lines printed thereon through utilization of the depth :
line generator circuit 64. In Figure 8 it can be seen that the ~-depth lines at 10 foot intervals are wider than the depth lines ` at 2 foot intervals and that depth lines at 50 foot intervals are wider and thus more outstanding in appearance than either the two foot or 10 foot interval depth lines.
Now, turning to Figure 9, there is shown a recording medium on which both depth and scale lines have been printed, as well as the depth numbers. In addition to the dis-tinguishing features of the 2, 10 and 50 foot depth lines, it can ~-be seen that one of the scale lines per track is darker than the rest. This is accomplished by inserting the desired card into the scale grid cara reader 38 of Figure 1. The depth track is - shown in Figure 9 as being located between tracks 1 and 2 and devoid of any printing other than the depth number. To ac-complish this, the scale grid card reader generates a signal designated "Depth Track InhiE~lt" (the means "NOT Depth Track Inhibit") which is utilized by the combining and logic circuit 42 to inhibit scale and depth lines from being printed in the depth track (see Figure 1 ).
A depth number 11300 is printed in the depth track.
It can be seen that there is one digit of this number printed every two feet for a ten foot interval. At 1304 and 1302 feet `' "zeros" are printed and at 1300, 1298, and 1296 feet the digits 311 are printed such that when examining the recoxding ,. ~'''"' ',, .. . .. . . .
.. . :
. ,, ' :, .

~5Z~73 medium, it is eYident that the he~vy depth corresponds to a . -j! depth of 11300 feet.
As discussed earlier, a trace is recorded on the recording medium 25 by periodically sweeping the cathode ray tube beam transvexsely across the recording medium and un-~'I blanking this beam at the proper time. If the well logging signal to be recorded has a slow rate of change, the marks 'l will be placed on a recording medium in relati~ely closely ~`
spaced apart positions. If the signal to be recorded has a fast rate of ch~nge, these marks will be placed on a recording medium at relatively widely spaced apar~ positions. This difference is undesirable since it presents a non-uniform log.
~ To alleviate thi~ problem each pulse position and pulse ; width modulators 23 individually operate to vary the width of the trace recorded on the recording medium in accordance : with the rate of change of the signal to be recorded.
To this end, referring to ~i~ure 10, there is shown one of the pulse position and pulse width modulators. In actuality there are as many modulators as there are signal channels but since all such modulators are indentical, it is only necessary to show one here. In Figure 10, the channel signal ~rom one of the low pass filters 22 ~in this case, the channel n signal is used) is applied to a vol~age comparator 140 where it is compared in amplitude with the weep signal -~
from the sweep circuit 24. When the ampli~ude of the sweep signal exceeds the channel n signal amplitude, the voltage comparator 140 changes from the "zero" to "one" state.
The channel n signal is also applied to a second voltage comparator 141 after being delayed by a delay circui~ ;~
142. The voltage comparator 141 also compares the channel signal with the sweep signal to yenerate a "one" upon the sweep signal amplitude exceeding the channel signal amplitude.

~ 1~52~73 The outputs of both voltage comparators 140 and 141 are applied to the input of an Exclusive OR gate 143 which changes from ~he ~zero" to "one" state when one,~but not both, outputs of the voltage comparators 140 and 141 are at the "one"
level. The leading edge of the resulting output pulse from the Exclusive OR gate 143 energizes a one-shot 144 and the output pulses from the exclusive OR gate 143 and one-shot 144 ~-are ORed together in an OR gate 145 to produce the "writing signal" for application to the line coding circuit 45 (see Figure 1). The output signals from the voltage comparators 140 and 141 are also ORed together in an OR gate 146 for application to the area coding card reader 47 for purposes to be explained later.
; Concerning the operation of the Figure 10 modulator and referring to ~igures llA-llE, Figure llA shows the sweep position signal and delayed and undelayed channel signals, the delayed channel signal being shown in dashed line form. -Figure llB shows the output pulses from the exclusive OR gate 143 and Figure llD shows the output pulses from the OR gate 145. The resulting recording trace is shown in Figure llE.
By CGmpariSOn of Figures llA and llB it can be seen that the pulse width of the output pulses from the Exclusive OR gate 143 will vary as a function of the rate of chan~e of the ~hannel signal to be recorded. Thus, as illustrated by t~e left-hand portion of Figures llA and llB,- these p~ulse wid~hs ` will be ex~remely narrow when the input channel signal does not vary in amplitude.
As se~n by the intermediate portion of Figure llA, when the channel signal begins to change in amplitude, the delayed channel signal will have ~he same change but at a delayed time. This causes the sweep signal to define a given time interval between the delayed and undelayed channel .
.
. ..
.

105247~1 signals which defines the pulse ~idth of the pulses of Figure llB.
At the righ~-hand side of Figure lLA, the input channel signal changes amplitude very rapidly, thus causing the sweep signal to define a long time interval between the time whe~ the sweep signal amplitude equals the channel signal to the time when it equals the delay channel signal.
Thus, it can be seen that the faster the rate of change of the channel signal, the longer will be the duration of the output pulse from the Exclusive OR gate 143. The one shot 144 acts to guarantee a minimum pulse width for the modulator output pulses such that minimum pulse width pulses will be generated when DC signals are being recorded. The combined output pulses from the exclusive OR gate 143 and one-shot l44 are shown in Figure llD and produce the recording traces of Figure llE.
Referring to Figure 12, there is shown an example of a recording made using the modulator of Figure 10. During t~e period when the channel signal does not vary in amplitude, it can be seen from Figure 12 that dots will be recorded on the recording medium. However~ when the amplitude of the signal begins changing, the transverse sweep lengths become longer, thus compensating for the increase in the rate of change of the input channel signal. The overall result is to produce a recording which is uniform in appearance regardless of the rate of change of the input channel signal.
Mow, referring to Figure 13 there is shown one of the parallel line coding circuits 45 of Figure 1 in detail. Since all of the line coding circuits are identical, it is only nec-essary to show one circuit in detail. The function of the line coding circuits is to code the line which is recorded on the recording medium 36 to thereby enable easy identification of each o the various signals being recorded. Each line coding circuit - ~LOS24~3 ¦ recei~es an instruction from the line coding card reader 46 ,~ produce a dotted~ dashed, long dashed, or solid line on the t recording medium.
One way of accomplishing this is to register a count for each sweep of the CRT beam and alternately blank and unblank ~he writing operation for a specified number of such sweep counts to produce the desired code. To this end, the sweep reset pulses from the sweep circuit 24 of Figure 1 are applied to an OR gate 150 which, aftex processing by some logic circuits, are applied to a divider made up of a divide by five counter 151 and a divide by eight counter 152.
To this end, the sweep reset pulses from the sweep circuit ~4 of Figure 1 are applied to an OR gate 150 which, after processing by some logic circuits, are applied to a divider made up of a divide by five counter 151 and a divide by eight counter 152. The feedback connections for the counters ~ -151 and 152 are selectable to produce the desired line coding pattern. Thus, fo~ example, a mark could be recorded for 40 .1 , . .sweeps and inhibited for 40 sweeps, or recorded for 160 sweeps and inhibited for 40 sweeps, etc. ~o perform the recording and inhibit function, the normal output of the last stage of the di~ide by eight counter 152 enables an AND gate 158 to pass the writing signal from the appropria~e one of modulators 23 to the combining and logi~ circuit 42.
As discussed earlier, the length of the dots or -~
dashes will be dependent on the rate of change of the channel signal to be recorded. In other words, if a do~ting pattern is desired where marks are inhibited from being placed on the recording medium for 40 sweeps and then recorded for 40 sweeps, .1 . . .
it can be seen that 40 sweeps for a DC signal will produce a much shorter line on the recording medium than 40 sweeps for a rapidly varying signal. -~. .

. . -j ~S~473 To provide a uniform line coding pattern regardless of the rate of change of the input channel signal, the writing signal from the proper modulator 23 enables an AND gate 153 which, when enabled~ passes high frequency clock pulses from a clock source 154 to the other input of the OR gate 150. Thus, when the channel signal has a high rate of change, more pulses are applied to the counters 151 and 152 than for the case of a 810wly varying signal. The frequency of the clock source 154 is chosen in accordance with the CRT beam sweep rate to produce the desired xesults.
Now, concerning how each of the individual line co~ing patterns are produced and firs~ concerning the dotting pattern, ' the output pulses from OR gate 150 are applied to one input of an AND gate 155~ and one input of an AND gate 156. The no~mal output of the last stage of the divide by eight counter 152 and , ~he dotting control signal from the line coding card reader 46 - enable the AND gate 156 to pass the pulses from the OR gate 150 to the count input of the divide by five counter 151 via or OR
gate 157. Thus, when the line coding circuit is in the dotting mode and the normal outpu~ of the last stage of the counter 152 is at the "one" level, the counters 151 and 152 will, in con-junctlon, proceed to count 40 pulses from the OR gate 150. At the end of 40 pulses, the last stage of the counter 152 changes to its complementary state, thus disabling the output AND gate 15B and enabling the AND gate 155 to apply pulses to the input of the counter 151 via the OR gate 157. A~ter 40 more pulses -~
have been counted, the normal output of the last stage of counter 152 returns to the "one" state, thus enabling the AND gate 158 to pass writing signals to the combining and logic circuits 42 of Figure 1 and enabling the AND gate 160 again. The process then repeats itself.
Thus, it can be seen that the line coding circuit of 529~73 Figure 13 will inhibit at least a selected portion of one writing j signal from passing to the combining and logic circuits 42. As `L a maximum, it could inhibit many writing signals. The criteria ~ar inhibiting the writing signals or portions thereof is not ~he ¦ number of writing signals themselves but the length of the line I being recorded on recording medium 36. This length is a functionI of the pulse width of the writing signals from modulator 23.
Thus, the AND gate lS3 will gate a ~uantity of clock pulses to the counters 151 and 152 per sweep depending on the rate of change of the channel signalO rhe application of the sweep reset signal to the OR gate 150 for counting by counters 151 and 152 l serves to set a minimum limit of one count per s~eep when a DC
¦ signal is being recorded. Looking at the extremes, if the channel signal has a low rate of change, a great many writing signals would be inhibited and if it has a high rate of change, a portion of one writing signal would be inhibited or if the rate o change is very hight several non-adjacent portions of one writing signal could be inhibited.
The dashing and long dashing operations are very similar to the do~ting operation except that the waveorm generated by ~he counter 152 will be unsymmetrical. This unsymmetrical waveform is produced by inserting a divide by ~ -; four counter 159 in th~ feedback path from th~ normal output of the last stage o counter 152 to the input of the counters 151 and 152. Thus, during a dashing operation, an AND gate 160 is enabled such that when the normal output of the last stage of counter 152 goes to the "one" level, the pulses from OR gate 150 will be applied to the divide by four counter lS9.
By so doing, the absence of a recorded trace will be 1/4-the length of the recorded traces on the record medium 36. To provide a long dashing operation, a divide by eight counter 161 is inserted in the feedback path. Thus, during such a long .

' . : ' ' ' .

~ 52~73 dashing operation, an AND gate 162 is enabled such that when the normal output of the counter 152 is at the "one" level, counters 161, 151 and 152 opérate in a serial fashion to count pulses from the OR gate 150. This arrangement dictates that the recorded traces will be eight times as long as the absence of such traces thus giving a long dash line.
To produce a solid line on the recorded medium 36, a control signal designated n solid" from the line coding card reader 46 sets the last stage of the counter 152 to its normal state such that the AND gate 158 is always enabled to pass writing signals.
Now referring to Figure 14, there is shown the area coding circuit 48 of Figure 1 in greater detail. The area coding circuits of Figure 14 are made up of twelve individual ;~
pattern generators which are ~tilized to generate the patterns shown in Figures 15A-15L. As discussed earlier, these coding ~'~ patterns are generated whenever a selected channel signal assumes a predetermined relationship to a second channel signal.
The area coding card reader 47 selects certain ones of the .. . .
pulses generated by the QR gate 146 (see Figure 10) of each modulator of the parallel position and pulse width modulators ,~
23 as "start" signals (start coding) and certain ones as ~Istopn signals. The area coding card réader 47 also selects certain ones of the divided clock signals from the binary counter 31 for application to the area coding circuits. In Figure 14, these signals are designated SC2, SC4, SC8, etc., with the number following "SC" indicating the stage of the counter 31, i.e., SC2 indicates that the second stage of the counter 31 has been selected.
The first circuit to be described will produce the area coding pattern shown in Figuxe 15A. This pattern usually designates oil. In Figure 14, a di~ide by four counter 171 :

" ~OSZ473 counts the trailing or rising edges of inverted sweep reset pu~ses, designated SR, produced by inverting the sweep reset pulses from the sweep circui~ 24 of Figuxe 1. The falling edges of the square wave output signal from the divide by ~-:
four flip-flop 171 and the inverted sweep reset pulses SR from the AND gate 172 energize the set and reset inputs respectively : :
of a flip-flop 173., The rising edges of the output signal from the/normal output contact of the flip-flop 173 toggle a flip-flop 174 which, when the normal output of flip-flop 173 is a~ the "one" level, enable a pair of AND ga~es 175 and 176 respectively to pass the sweep counter signals SC2 and SC2 .
respectively to a "trace length one-shot" 177~ The pulse width .
of the pulse generated by the one-shot 177 is set such as to produce the desired trace length on the recording medium, i.e., - :. .- .
it determines the unblanking time of the cathode ray tube 25. -~
To insura that the oil coding pattern is printed only when one selected channel signal has a predetermined relation~
ship with the other selected channel signal, the trace length .:;.
pulses from one shot 177 are combined in an AND gate 178 with the start and stop signals from the area coding card reader 47.
The card reader 47 provides for inversion of the stop signals.
The card reader 47 selects those area coding control .;
signals which are utilized as the start and stop signals for ~ . . .
each of the pattern generators of Figure 14. Thus, for example, if the oil coding pattern generated by the circuit 170 is to be printed on a recording medium whene~er the channel 2 signal is ~ .
greater in amplitude than the channel 4 signal, the card reader 47 will select the channel 4 signal as the stop signal and apply ` ~ .
these to the oil coding circuit 170. To insure that no scale and depth lines are recorded while the area coding pattern is being recorded, the start and stop signals from the area coding card reader 47 are combined in an AND gate 179 to produce a j .
'~

- ,. : , . . ,, . ~ . , , . . . . . . . . .
- . . . . .
, ' . . . ': '': ~

- ~L lg5Z~3 control signal representative of the time interval during which the area coding pa~tern is being generated. This area coding blanking signal is applied to the combining a~d logic circui~ 42, ~
which as will be discussed later, blanks out depth and scale -lines while the area coding pattern is being recorded.
To better understand how this conditional area coding operation takes place, refer to the oil coding circuit 17 of Figure 14 in conjunction with Figures 16A-16F. Figure 16A is an illustration of the sweep signal overlayed on the channel signals which are selected by the area coding card reader 47 - as the start and stop signal~ for use by the area coding cir-cuits. Figure 16B'shows the sweep reset pulses generated by the sweep circuit 24 of Figure 1.
' It will be re alled from the discussion of the modulator of Figure 10 that the output of the OR gate 146 will rise to the "one" level upon the sweep voltage exceeding the channel sig~al amplitude and will remain at that level until the sweep signal amplitude is less than the channel signal amplitude. Thus the area coding control signal generated by ~he modulator which is processing the signal designated "start" in Figure 16A will produce the area coding control - signal of Figure 16C. Likewise, the modulator which is pro-cessing the channel signal designated ~stop" in Figure 16A
will produce an inverted version of the area coding control signal shown in Figure 16D. (The stop signal is illustrated in Figure 16D~) Through action of the area coding card reader 47, the signal in Figure 16C becomes the start signal and the ; control signal of Figure 16D ~ecomes the stop signal which are applied to the AND gates 178 and 179.
The conjunctive function, start stop is shown in Figure 16E and, ~hrough the action o~ AND gate 179, eomprises the area coding blanking signal. Likewise, through the action ~, ' .

11)5;~ 3 o ~ND gate 178, start and ~top enables the area coding signal pulses from the ~race length one-shot, shown in Figure 16F, to be applied to the combining and logic circuit 42 as the area coding writing signal whenever the normal output of the flip-flop 173, shown in Figure 16G, is at the "one" level. Since the flip-flop 173 is set only oncé every four sweeps, after the sweep reset pulse 180 of Figure 16B resets flip-flop 173 tsee Figure 16G), this flip-flop will remain in a reset state for the next four sweepsO Then it will be set by the fourth reset sweep pulse after pulse 180 to allow the area coding signal of Figure 16F ~o b~ passed.
It can, therefore, be seen that the oil coding circuit ~
170 will operate to produce evenly spaced dots on the recording ~ -! medium 36 for one out of every four sweeps in ~he area bounded -by the logs selected by the area coding card reader as the start and stop logs. The space between each dot in the direction of the sweeping beam ~transverse to the record medium 36) will be deter-mined by the counter signal SC2. The toggle FF 174 changes state, every fourth s~leep, and alternately enables gates 175 and 17~ thu~
~0 alternately connecting SC2 and SC2 counter signals to the one-shot 177. This staggers the dots printed on alternate lines of dots.
Now, concerning the circuit for producing a coding pattern which d~signates "gas", refer to the "gas coding circuit"

: :.
182 of Figure 14. This gas coding circuit 182 operates in a -manner very similar to the oil coding circuit 170 except that only one sweep out of eight i~ utilized to produce dots on the recording mediums and these dots are spaced twice as far apart as those for the oil coding circuit 170.
The major portion of the gas coding circuit 182 is 30 the logic oircuit A portion of the oil coding circuit 170. In circuit 170, this logic circuit A comprises all of the oil coding circuit 170 except the divide by four circuit 171 and is that . . , '~

5i24~73 portion of the oil coding circuitry enclosed by the dashed lines.
To produce the recording of dots once every eight ;;
sweeps, the square wave output signal from the divide by four flip-flop 171 of circuit 170 is applied to a divide by two flip-flop 183. The output of the divide by two flip-flops 183 is thus equal to SR/8 and is applied to the set input of the corresponding flip-flop 173 within the logic circuit A of the gas coding circuit 182. To produce the wider spacing of dots during those sweeps when dots are recorded, the SC4 and SC4 signals from the binary counter 31 of Figure 1 are applied to AND gates within the logic circuit ~ of the gas coding ~ .
cixcuit 182 which correspond with the AND gates 175 and 176 of the oil coding circuit 170. The resulting pattern produced on the recording medium is illustrated in Figure 15B.

Looking now at Figure 15C, there is shown the area coding pattern used to designate "sand". It can be seen that the dots recorded for this pattern are further spaced apart than the dots for the pattern shown in either Figures 15A or 15B. Returning to Figure 14, the "sand logic circuit" 185 acts to produce this coding pattern of Figure 15C. The sand logic circuit includes the logic circuit A discussed earlier.
To producP the wider spaced dots, the SR/8 square wave signal from the flip-~lop 183 is applied to a divide by two flip-flop 186 within the sand logic circuit 185 so that the dots will be recorded only once every sixteen sweeps. Moreover, the SC8 and SC8 signals from the binary counter 31 of Figure 1 are applied to the AND gates of the sand logic circuits 185 which correspond to the AND gates 175 and 176 of the logic circuits A of the oil coding circuit 170.

The next pattern generator to ~e discussed will pro-duce the coding pattern seen in Figure 15D. This Figure 15D

. , ' : , , ~(~S29~73 pattern comprises alternate ligh~ and dark stripes which run transversely of the record medium. This Figure l5D pattern designates "movable oil". To produce this pattern is the function of the "movable oil coding circuit" 190 of Figure 14.
The coding circuit 190 alternately passes and inhibits the pulses generated by the trace length one-shot 177~of the oil coding circuit 170 during alternate two foot sections on the recording medium.36.
To accomplish this, the output pulses from the trace length one-shot 177 of circuit 170 are applied to an AND gate 191 within the movable oil coding circuit 190. The start and stop signals from the area coding card reader 47 enable the AND gate 191 when the conditional coding fDrmat is satisfied.
To provide the alternate recording and inhibiting of the pulses generatea by the trace length one-shot 177 during successive two foot sections, the two foot sweep signal from the depth interval detector 63 and the sweep control signal from sweep circuit 24 of Figure 1 are combined in an AND gate 192 and the trailing edge of the resulting output pulses from AND gate 192 trigger a toggle ~lip-flop 193 whose normal output enables the AND gate 191. By this arrangement, the flip-flop 193 will enable the AND gate 191 once every other two foot section to produce th~ pattern indicated in Figure lSD.
The start and stop signals are combined in an AND
gate 194 whose output signal is the area coding blanking signal which is applied to the combining and logic circuits 42 to blank out the writing of scale and depth lines when the movable oil coding pattern is being recorded.
The next pattern generator to be described produces area ~oding pattern shown in Figure 15E. It can be seen that this area coding pattern is similar to the one shown in Figure - 15D except that the dotting pattern produced for the dark ~"
--43-- :
' :' ., , . - ~ .. .. . ~
. .
.
,,., '. ' '' .'' . ' 105247;~
sectio~s is more wiaely dispersed, thus giving a lighter or greyish appearance to the dark sections thereof. This pattern of Figure 15E designates '1movable gas n and is generated by the "movable gas coding circuit" 196 in Figure 14.
The movable gas coding circuit 196 includes a toggle flip-flop 193A which is toggled by the output pulses from the AND gate 192. An AND gate l91A is responsive to the start and stop signals selected by the area coding card reader for the movable gas coding circuit 196 and the normal output of the flip~flop 193A for passing the trace length pulses produced by logic circuit A of the gas coding circuit 182. These passed or gated SR/8 pulses constitute the area coding writing signal from the movable gas coding circuit 196. An AND gate 194A
responds to the start and stop signals selected by the card reaaer for the movable gas circuit 196 to generate.the area :1 coding blanking signal for coding circuit 196.
The difference between the movable gas coding circuit 196 and the movable oil coding circuit 190 is that in the former, the AND gate l91A is responsive to the pulses generated by the trace leng~h one-shot (corresponding to one-shop 177 of coding circuit 170) within logic circuit A of the gas coding circuit 182 while the latter uses the trace length pulses from one-shot 177. Thus, the oil pattern of Figure 15A will make up the dark areas of the movable oil pattern of Figure 15D while the gas pattern of Figure 15B will make up the dark areas of the Figure 15E movable gas pattern. Since the oil dotting pattern of Figure 15A is denser and thus darker in appearance than that for the gas coding pattern of Figure 15B, the dark sections of Figure 15E
will appear lighter than those of Figure 15D.
The next pattern generator to be described produces the coding pattern shown in Figure 15F. This coding pattern comprises the absence of all marks in the area for which coding .

.~, . . .. .. . . ..... . .
-: : . . . . ~ . . . .. .
,' ' ' ' ' ' ., ' :, ' . '' . " ' ' ' " ~ . ', , is desired and represents porosity. To produce this pattern is the functIon of the poro~ity coding circuit 198 of Figure 14~ The porosity coding circuit 198 through an AND gate 199 merely responds to the stop and start signals selected by the area coding card reader 47 for the porosity coding circuit to prevent the writing of all data between the start and stop logs. The output signal from AND gate 199 constitutes the area coding blanking si~nal for the coding circuit 198.
The next pattérn generator to be described produces the coding pat~ern of Figure 15G, which is ~he coding pattern for "water". This coding pattern comprises a light area be-tween the start and stop logs, broken only by the presence of scal~ lines. To provide this coding pattern, a "wa~er coding circuitl' Z00 of Figure 14 includes an AND gate 2~I which is responsive to the start and stop signals from the card reader 47 for this circuit for generating the area coding blanking ;
signal which inhibits the writing of data in the area bounded -, .. . . . .
by the star~ and stop logs. Then, to produce the scale lines, the scale line signal from the OR gate 41 of scale line cir-. i , .
cuit 37 of Figure 1 is applied to an AND gate 202 which is also responsive to the start and stop signals for producins the area coding writing signal for the water coding circuit. Thus, the AND gate 202 reinserts the scale line signals which have been inhibited by the action of the AND gate 201.
The next pattern generator to be described produces the coding pattern of Figure l5H which is the pattern for a type of shale which, or present purposes, if designated shale No. 1. As seen in Figure lSH, this coding pattern is defined by vertically spaced apart dashed lines wherein the dashes are staggered from one depth level (transverse or vertical lines on `

' the record medium) to the next and is generated by the shale No. 1 coding circuit 205 of Figure 14.
: :

;,. . .. ; . ,. , , :
''..' .' ,, ~

5~473 Within the coding circuit 205, a flip-*lop 206 is set by the S~/16 pulses and reset by the SR pulses. The rising edge of the normal outpu~ o~ flip-flop 206 toggles a toggle flip-flop 207 whose normal and complementary outputs enable a pair of AND gates 208 and 209 respectively to pass the sweep counter 31 square wave signals SC16 and SC16 respectively. The outputs of both AND gates 208 and 209 energize a trace length one-shot 210 which generates a pulse whose duration is selected to produce a trace length corresponding to those shown in Figure l5H. The output pulses from the trace length one-shot 210, alo~g with the start and stop signals selected by the area coding card reader 47 for this coding circuit are combined in an AND gate 2110~ The resulting output signal from ~ND gate 211 constitutes the area coding writing signal for the shale No. 1 coding circuit 205. An AND gate 212 is responsive to the start and stop signals selected for this coding circuit for producing the area coding blanking signals.
It can be seen that the flip-flop 206 will be set once every sixteen sweeps to there~y cause the energization of the trace length one-shot 210 once per 16 sweeps. The vertical or transverse distance between the initiation of each trace written on the recording medium is set by the SC16 and SC16 counter signals. By way of comparison, this distance for the shale No~ 1 pattern is eight.times greater than that for the oil pattern of Figure 15A since the counter signals SC2 and SC2 are-used by the oil coding circuit 170. It can be seen that every othertime the flip'flop 206 is in its normal state, one or ~..
the other of the ~ND gates 208 and 209 will be enabled to pass the SC16 and SC16 signals respectively thus causing the traces .
to be staggered on the recording medium 36.

.; . .:
The next pattern generator to be described will pro- :
duce the coding pattern shown in Figure 15I which corresponds to ~:

-46- :

.

.'. . ~ ' . ' , . !

,, :' ,, , ,' '.. . . .
' ', ' ' ' " ' . . ' ' :' . ' . ~ , . ' . ' .

29~3 a second type of shale, designated "shale No. 2". As seen in ~igure 15I, this coding pattern is similar to the coding pat-tern of Figure 15~ except that the vertica~y directed dashes are longer and further spaced apart. This coding pattern is generatedby the shale No. 2 coding circuit 215 of Figure 14.
To produce this pattern, the coding circuit 215 uses the normal output of the flip-flop 207 of the coding circuit 205 to en-able a pair of AND gates 216 and 217 which are also responsive to the sweep counter signals SC32 and SC32 respectively. The I 10 output pulses from AND gates 216 and 217 energize a trace length one-shot 218. An AND gate 211 passes these trace length pulses as the axea coding writing signal for coding circuit 215 when the start and stop signals sëlected for this circuit 215 are both at the "one" level. As before, an AND gate 221 responds to the start and stop signals selected for circuit 215 to pro-duce the area coding blanking signal-for ~his circuit.
Since the normal output of the flip-flop 2Q7 will be one-half the frequency of the flip-flop 206 output signal, the .
sweeps for which traces are recorded will be twice as far apart as for the shale No. 1 coding pattern. ~ikewise, since the SC32 and SC32 counter signals are used instead of SC16 and SC16, the trace length one-shot 218 of the shale No. 2 coding circuit 215 is energized one-half as often as for the shale No. 1 coding circwit 205. The trace length one-shot 218 ha~ a timing circuit set to produce pulses having a pulse width greater than that for the trace length one-shot 210 of coding circuit 205 to produce longer length dashes on the record medium 36. To provide for staggering the dashes on alternate writing sweeps, the AND gates 216 and 217 are alternately enabled by the~flip-flop 219 to pass the counter signals SC32 and SC32 on alternate writing sweeps.
The next pattern generator to be described will pro-duce the coding pattern of Figure 15J which designates limestone.

,. '.

, :: . , ' :
, ' ` ' `, ; `~ ': ~
, : .

This coding patter~ is made up of a plurali~y of spaced vertical lines having interconnecting horizontal lines between each pair of vertical lines, which horizontal lines are vertically stag-gered from one pair of vertical lines to the next. The circuit for generating this pattern is the limestone coding circuit 225 of Figure 14.
To produce the spaced apart vertical lines, and AND
gate 226 is responsive to the coincidence of the two foot sweep signal and sweep control signal from the AND gate 192 and the start and stop signa~s selected by the area coding card reader 47 for this coding circuit 225 to produce a vertical (transverse -to the record medium) line once every two feet. To produce the ~ -staggexed hoxizontal lines, the rising edges of the two foot sweep control signal from AND gate 192 toggles a divide by two ` flip-flop 227 whose normal and complementary outputs enable a pair of ~ND gates 228 and 229 respectively. When enabled, the AND gates 228 and 229 pass the sweep counter signals SC32 and SC32 to energize a trace length one-shot 230. The time period of the pulses generated by the one-sho~ 230 are small so as to produce dots on the recording medium. The output pulses from the trace length one-shot 230 are then combined in an AND gate 227 with the start and stop signals selected for this coding circuit so as to produce writing signals which will produce the ;
staggered horizontal line shown in Figure 15J.
The output signals from AND gates 226 and 227 are ~-then combined to produce the area coding writing signal fox the limestone coding circuit 225 to produce the pattern of Figure 15J.
As before, the area coding blanking signal is produced by com-bining the start and stop signals in an AND gate 228.
Summarizing the operation of this limestone coding circuit 225, the AND gate 226 opexates to produce the vertical lines shown in Figure 15J. (In actuality, the area coding ,, ~.

:, . ' : . , : ' . , ~ , ', : , :

blanking signal produced by the AND gate 228 inhibits the writing of depth line between the start a~d stop logs and the AND gate 226 merely reinserts the two foot depth lines in this area.) To produce the horizontal lines, the edge of one of the SC32 and SC32 square wave counter signals periodically energizes the trace length one shot 230 to produce dots on the recording medium at the same vertical position during each sweep. Thus, during a succession of sweeps, a horizontal line will be pro-duced. Then, when the next two foot depth line is reinserted by the AND gate 226 in the area normally set aside for area coding, the two foot sweep control signal from AND gate 192 which causes this depth line to be reinserted also toggles the divide by two flip-flop 227 t~ reversé the enable-disable configuration AND gates 228 and 229 and thus of SC32 and .SC32.
By ~o doing, the staggering of the horizontal lines between vertical line pairs is produced.
The next pattern generator to be described produces the area coding pattern of Figure 15K, which represents dolomite.
As see~ in Figure 15K, this pattern is very similar to the limestone coding pattern of Figure 15J excep~ that the hori-zontal lines for limestone are slanted for dolomite. To produce this coding pattern is the function of ~he dolomite coding cir-cuit 235 of Figure 14.
The reinsertion of the two foot depth line is produced ; in this circuit 235 by an AND gate 236 which is responsive to the coincidence of the two foot sweep signal and the sweep control signal, and the start and stop signals selected by the area coding card reader 47 for this coding circuit. This is essentially the same function as was perfonmed by AND ~26 of the limestone coding circuit 225. To produce the slanted lines between the two foot vertlcal lines, the rising edges of the square wave output signals produced by either of the AND gates .
.. . .
.: , . ' , ' ' ~, :

/
~52~73 228 or 229 of the limestone coding circuit 225 set a flip-flop 237. When the ~lip-flop 237 is set, an AND gate 238 is enabled to pass the clock pulses designated CL from the sweep circuit 24 of Figure 1 to the count input of a down counter 239 ("down counter" signifies that this counter 239 subtracts a count for each pulse supplied thereto). When the contents of the down counter 239 have been completely subtracted away, the leading edge of the resulti~g borrow pulse resets the flip-flop 237.
When ~he *lip-flop 237 is reset, a trace length one-shot 240 generates a short time duration pulse which, during the coincidence of the start and stôp signals selected by the area coding card reader 47 for this coding circuit, is passe~ by an AND gate 2~1 as part of the area coding writing signal for this coding circuitO The outputs of AND gates 236 and 241 comprise the area coding writing signal for the dolomite coding circuits.
What has been described thus far in the aolomite coding circuit 235 would produce the limestone pattern of Figure lSG
given by the limestone coding circuit 225, i.e., the lines be-tween t~e vertically extending two foot depth line would be horizontal. To provide for slanting lines, a binary counter `~242 is advanced one count for each sweep reset signal applied to its count input, i.e., it is advanced one count per sweep.
: .
~- The leading eage of the sweep reset pulses causes the counter 242 to advance. The contents of the binary counter 242 are trans~erred to the dswn counter 239 in response to the trailing edges of the pulse from the one-shot 240. Thus, for each sweep of the CRT b am, the number placed in the down counter 239 in-.. . .
creases by one count thus causing the down counter 239 to receive one more CL pulse per sweep~ for the contents thereof to be emptied. Conse~uently, it takes a slightly greater time for each additional sweep for the trace length one shot 24~ to be energized thus producing a slanted line.
: ~ .

... ,.. . -- - . . .; ; - .
.
.. . , ~ .

~L~5;~73 ~
At every two foot depth interval, the binary counter 242 is reset by the two foot sweep control signal from AND gate .
192 to initiate the production of the slanted line between the next pair of two foot depth lines. Since the two foot sweep control signal toggles the flip-flop 227 for alternately en-abling AND gate 228 and AND gate 229, the slanted lines will be staggered because of the alternate selection of the SC32 and SC32 counter signals by the AND gates 228 and 229.
The area coding blanking signal is produced by an AND gate 243 in response to the start and stop signals in the usual manner.
The last pattern generator to be described produces the coding pattern of Figure 15L which identifies anhydrite and is produced by the anhydrite coding circu~t 245~ This coding pattern is a slanted line pattern within the area bounded by the . start and stop logs selected by the card reader 47. To produceD` this pattern a divide by 40 counter 247 co~nts both the clock ` pulses CL from the high frequency clock 29 of Figure 1 and the sweep reset pulses from the sweep circuit 24 of Figure 1, which are combined in an OR gate 246. An edge of the square wave out- -; put signal from the counter 247 energizes a trace length one-shot 248 which generates pulses having a short time duration so as to produce dots on a recording medium. These pulses generated by `:
~` the one-shot 248 are combined in an AND gate 249 with the start and stop signals so that the coding pattern will be produced -: only between the selected start and stop logs. The start and stop signals are also ~ombined in an AND gate 250 to produce the :
area coding blanking signal in the same manner as discussed -~ previously.
Neglecting for the moment the effect of the sweep re-set pulses, the clock pulses would, after division by the divide by forty counter 247, cause a dot to be placed on the recording :. -., ;.

.. , :
.~ ~
'~ , :

5~Z4'73 medium at the same Yertical (or transverse) position for each sweep, thus producing a plurality of horizontal linas spaced apart a distance corresponding to CL/40. ~owever, since the sweep reset pulses are also counted by ~he counter 25?, the net effect is to move the vertical point at which the dot is re- ::corded for~each sweep a given vertical increment. Thus, since the recorded dot is moved a given vertical increment for each sweep, the net result is to produce slan~ed lines within the area defined by the start and stop logs.
Now, rPferring to Figure 17, there is shown the combining and logic circuit 42 and the CRT brightness control :
circuits 50 of Figure 1 in greater detail. First, concerning the combining and logic circuit 42, it is the function of this . . circuit to combine the writing signals.from the parallel line .` coding circuits 45, the area coding circuit 48, as well as the trace intensified writing signals from card reader 49, and the scale and depth line signals from the scale..line circuit 37 and -depth line g~nerator 64 for application to the CRT 25. In .~ :
~, addition to these combining operation~, circuit 42 also performs certain logic operations to give a desired recording format.
The line coded writing signals from ~he line coding circuits 45 of Figure 1 are combined in an OR gate 260 and the area coding writing signals from the area coding circuits 48 :.
are combined in an OR gate 261. The outputs of OR gates 260 and 261 are combined in OR gate 262 for application to one in-put of an AND gate 263.
As discussed earlier, no data is to be written on the recording medium while the initial scale line is being printed .
: and during the fly-back of the cathode ray tube beam, i.e., during sweep reset. Therefore, the initial scale line and sweep :
reset pulses, after inversion by a pair of NAND gates 264 and 265, respectively, are applied to individual inputs of ~he AN~

: ~ ,, ~ (3 S2473 gate 263 so as to inhibit any writing signals from OR gate 262 during printing of the initial scale line and fly-back of the cathode ray tu~e beam. The ou~put of the AND gake 263 is applied to a limiter circuit 266 which sets the desired voltage level for the outpu~ signals from AND gate 263 and then applies the signals to the CRT brightness co~trol circuit 50.
The scale and depth lines are combined i~ an OR gate 267 for application to a limiter circuit 268 which performs the same funckion as limiter circuit 266 and then applies the scale and dep~h line signals to the CRT brightness control circuit 50 To insure that a depth line signal is generated only during the time the beam is being swept across khe usable portion of the recording medium, the depth line signal and sweep control sig-nal are combined in an AND gate 269 before being applied to the OR gate 267. Moreover, since as discussed earlier, scale and depth lines are not to be written in the depth track, thP depth track inhibit signal from the scale grid card reader ! 38 (see Figure 1) is used to disable the AND gate 269/and an AND gate 270 to which the scale line signals are applied whenever the CRT beam is being swept through the depth krack. Also depth and scale lines are not to be recorded whenever one of the area coding pattern generators is operating to produce a pattern (except where the pattern generator itself reinserts the depth or scale line) or when a channel signal is being recorded. To accomplish this function, the area coding blanking signals from the area coding circuits 48 are combined in an OR gate 271 and the output of this OR gate is combined with the output of AND
gate 263 in an OR gate 272. The output signal from the OR gate 272 thus represents the combination of the area coding blanking signal and the line and axea coding writing signals. Since scale and depth lines are not ko be recorded when any of these other signals are processed ~or recording, khe output control ..

`;
~52~73 : signal from OR gate 272 is inverted by a NAND gate 273 and applied to the input of an AMD gate 274, ~o which also is ; supplied the output from OR gate 267. Thus, the AND gate 274 will be disabled whenever the channel signals are being recorded and during area coding.
In addition to the above, the combining and logic circuit 42 also combines the trace in~ensifier signals from the trace intensifier card reader 49 of Figure 1 in an OR gate 275, :
.I and the amplitudes of the signals from OR gate 275 are limi~ed ~:
10 by a limiter circuit 276 before application to the CRT bright-; ness control circuit 50. The amplitude level of the limiter ;
circuit 276 is set high enough to enable a higher amplitude :
level for these trace intensified output signals from OR gate ;
275 than the scale and line signals from gates 267 and 274 and the line and area coded wr~ting signals from AND gate 263.
Now, concerning the CRT brightness control circuit ~:~
portion of Figure 17, the line and area coded writing signals, `~
scale and depth line signals, and trace intensifier signals from the limiter circuits 266, 268, and 276 respectively of 20 the combining and logic circuit 42 are fed to the negative or inverting inpu~ of an operational amplifier 280 via summing and weighting resistors 281, 282, and 283 respectively. The values of these resistors 281, 282 and 283 are set in con~
junction with the limiting values of the limiter circuits 266, 268 and 276 ~o bring about the proper relationship of trace intensities for the coded writing signals, scale and depth line .~ signals, and trace intensifier signals. These combined signals ., ~ .
are then further processed by the CRT brightness control circuits 50 for use in unblanking the CRT beam.
Wi~h a CRT having a fiber optic faceplate, the anode ~I ~. . , must be operated at ground potential, thus nece~ssitating that the grid and cathode be at a high negative potential, e.g., :: .. .. . .
: : .

.. . .
.
, ,- '.. ,',,,', . . ': ~ . .',' :

:
~ 5Z9~73 :`
approximately -10,000 volts. Since the signals of the opera-tional amplifier 280 are within a few volts of ground potential, these signals must be translated through a level of thousands of volts. To alleviate this problem, a transformer 284 isolates the two circuits and the amplitude of a high frequency signal produced by an oscillator 282 is controlled by the output signals from amplifier 280. To this end, the amplifier 280 signals control ~he gain of a variable gain amplifier 281 to which the high frequency signal from oscillator 282 is applied. The out-put signal from amplifier 281 feeds the primary winding 283 of a transformer 284 with one side of the primary winding 283 being connected to the same circuit ground as the amplifier 283. On ; the secondary side of the transformer 284, the signals are detected by the detector 28~r i.e., converted to signals which resemble the signals produced by the amplifier 280, and applied to an amplifier and pulse shaper 286. This circuit 286 operates ;
to produce the final amplification to obtain the voltage level necessary for the cathode ray tube 25 and shape the pulses in a manner to compensate for the non-linear effects of the cathode ray tube 25.
As discussed earlier, the beam intensity of a cathode ;I ray tube can vary during the operation of the tube. Of course, such a variation in beam intensity would be undesirable for present purposes because it would tend to vary the quality of the recording. To alleviate this problem, a current to voltage -converter 287 monitors the beam current at the anode of the cathode ray tuhe 25 and supplies a voltage proportional thereto to the summing input of the amplifier 280 to thereby maintain this beam current constant. However, since the beam current is being modulated in ac~ordance with the inormation ko be recorded, the beam current cannot be monitored indiscriminately because o the wide fluctuation or variation in this modulation during any given sweep.

~55-'. ' ,: . , 1~5Z4~3 To provide a valid measure of beam current, a sample and hold circuit 288 i5 responsive to the initial scale line signal from the scale line circuit 37 of Figure 1 for instruct~
ing the sample and hold circuit 288 to sample the voltage out- ;
put of the converter 287 only when the initial scale line is being recorded. ~t will be recalled from the discussion of Fiyure 1 that the initial scale line pulse was combined with the other scale line pulses in the OR gate 41 for application to the combining and logic circuit 42 as the "scale line sig- -nals~. It will also be recalled from the discussion of the co~hining and logic circuit 42 of Figure 17 that the initial ;~
scale line pulse caused all other writing signals to be in~
hibited. Thus, it can safely be assumed that the output signal from the amplifier 280 will always be of constant amplitude while the initial scale is being recorded.
Since the sample and hold circuit 288 operates to sample this beam current only when the initial scale line is being recorded, the beam current can be measured once per ' sweep and adjusted in response to this measuxement to provide the desired beam intensity throughout the remainder of the sweep. To this end, the ~utput signal from the sample and hold circuit 288 is applied to a low pass filter 287 which filters out transient occurring during this sampling process and applies the measured beam current indication signal to a suitable meter 290 and to the summing input of the amplifier 280 via a summing resistor 291. The time constant of the low pass filter 289 can be selected high enough to prevent one or ; two erroneous measurements from completely upsetting the appearance of the recording, i.e., the feedback system will only respond to relatively slow changes in beam current intensity.
A "brightness adjust potentiometer" 292 also provides , : ' :. ' , ' . . " : . . : : ' :, .: ~

current to the summing input of the amplifier 2B0 ~ia a summing resistor 293. The posltion of the' potentiometer 292 can be preset to give the desired brightness level.
' The recording system described up to this point , ', derives data from telemetry equipment for recording. It would also be possible to record data while the exploring device ` which makes the measurements is moved through the borehole. ; , ,, This could be accomplished by recording the measurements ~ -derived directly from the downhole exploring device or recording -thi~ data after it has been digitized by a digital tape recorder., ; 10 First concerning the recording of data from a digital tape recorder simultaneously with writing the well logging measurements on magnetic tape, refer to Figure 18. In Figure 18, a well tool 300 is suspended in a borehole 301 by a multi-conductor cable,302 for investigating the suxrounding earth ; formations 303. The measurement signals produced by the well "~
, tool 300,are transmitted to suitable signal processing circuits .,~ - .
~', 304 over ~he conductors of the cable 302. The signal processing `' circuits operate to, for example, reference the signals to a - :
common reference potential and depth. The processed signals are "
' then applied to a digital tape recorder 305 which digitixes the meausurements and writes them on magnetic tape. The tape '-' recorder 305,could comprise any digital tape recorder. One example o~ a suitabie tape recorder is disclosed in U.S. Patent No. 3,457,544 granted to G. R. Miller et al on July 22, 1969.
This Miller et al tape recorder produces a plurality ""`
of signals which are used by the recording equipment of the ' ,~

,, present invention. It produces a plurality of channel selection signals 306 which designates the channel for which PCM data on a conductor 307 corresponds to. It also generates shift pulses for use by exterior e~uipment in shifting the PCM data into a ', suitable entry register and a "shift pulse window" fox use in properly gating the shi~t pulses to insure that the proper ~L~SZ~3 number of shift pulses are used. Pinally, it generates a "depth word" signal whenever a depth word; is on the PCM data line 307.
To produce the digital data words a~ a ~unction of borehole depth, a shaft 313 which is rota~a~ly connected ~o a wheel 314 in rotatable engagement with the cable 302 is connected to the input of the tape recorder 305. This shaft causes a circuit within the tape recorder 305 to generate incremental depth ., " .
pulses at given depth increments which are used to initiate the digitizing operation. For moxe information on this tape ; 10 recorder and how it produces these signals, refer to the Miller et al Patent No. 3,457,544.
Now concerning how the digital data from the tape recorder 305 is processed for application to the recording equip-men~ of Figure 1, the PCM data line 307,from the tape recorder 305 is connected to the inputs of a plurality of individual storage registers 308. The particular register which the PCM
data is entered into i5 selected by the channel designation sig-; nals on conductors 306, i.e., one channel designation conductor at a tLme will be active to thereby activate one storage register at a time to en~er the PCM data. The shi~t pulses and shift pulse window signal from the tape recorder 305 are combined in an AND gate 309 for application to each of the individual stor-; age registers 303. Thus, a particular storage register will be selected by one of the channel designation signals and the PCM
data will be entered into this selected register under control of the gated shift pulses.
~ The output stages of the storage registers 308 are ; connected to diyital to analog converters 309, the output stages of each storage register 308 being connected to an individual digital to analog converter. Thus, each converter 309 will produce an analog output signal whose amplitude is proportional to the digital number contained in each storage register 308, i.e., one analog signal per channel.

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~ SZ~3 : As set forth in the Miller et al tape recorder patent ; word 1 of each frame is reserved for ~he depth word. Since there is no need to convert depth words into analog quantities, . , .
the analog signals from converters 309 are sampled during the time period when the depth word is being processed by the tape recorder 305. To this end, the leading edge of the depth word control signal from tape recorder 305 energizes a "strobe one-shot" 310 which applies a stxobe pulse to suitable sample and hold circuits 311. ~en strobed, the sample and hold circuits 311 sample the analog voltages from the digital to analog converters 309. T~e stored analog signals in sample and hold circu~ts 311 are then applied to the filters 22 of Figure 1 in place of the signals from the telemetry unit 20. ;~
~ A plurality of bias circuits 312 opexate to select-ively bias the analog well logging signals to place them in selected tracks on the recording medium. In the Figure 1 system, it was assumed that this bias operation was taken care of prior to processing of the data by the Figure 1 circuits, i.e., the ; data output from the input equipment 20 already include the proper bias. Of course, if desired, bias circuits could be included in the Figure 1 apparatus (just after the low pass ilters 22) to perform this operation.
To supply the depth data to the~Figure 1 recorder circuits, the shift window, depth word designation signal and . .
shift pulses are all applied to the AND gate 91 of Figure 4 so as to enable the PCM depth word to be entered into the entry register 90. The depth word is then processed in the manner discussed earlier to provide depth indications on the recording medium.
In ~his case where the well logging measurements are recorded while they are being made by the wall tool 300, the recording medium is driven by the shaft 313. In this c~se, also -~ ~05;~4~73 for optimum results, the C~T beam sweep repetition rate should no~ be at a constant frequency. Of course, for good recording resollltion, there should be plurality of sweeps between sampling and digitizing of the well logging measurements. In the Miller et al tape recording system, the depth word designation signal is generated every time the well logging measurements are sampled, for most applications. Thus, the strobe pulse from the one-shot 310, which was energized by the depth word designation signal, is applied to a sweep pulse generator 315.
The generator 315 generates a plurality of pulses per strobe pulse which are applied to the set input of the sweep control flip-flop 27. In this embodiment, the 120 Hertz pulse generator 26 would be disconnected.
The sweep pulse generator 315 could take the fonm of a pulse generator which generates a fixed number of pulses when .. ,; . .
; energized~ Each generated pulse would energize a recorder drive stepping motor 316 which whçn energized, would cause the record-ing medium to step a predetermined incremental distance. This .~ . .~ . . . : .,, , .-stepping of the recording medium is synchronized with the sweep of the beam across the face of the cathode ray tube.
It is not necessary to use a digital tape recorder to supply "real time" data to the recorder of the present invention.
Instead, the well logging measurements could be applied directly to the present recorder. Turning to Figure 19, there is shown such an arrangement. The well logging measurements rom signal processing circuits 304 axe applied dixectly to parallel sample and hold circuits 320. To strobe the circuits 320, a depth pulse generator 321 generates a pulse each given incremental movement of the shaft 313. These depth pulses also energize the sweep pulse generator 322 which performs the same function as the generator 315 of Figure 18.
To provide the depth information to the recording . . . :
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,~ : ' .; ' ' .. . . . . . .

s ~ID5~73 equipment of the present invention, the shaft 313 is connected to a depth encoder 343 which can, if desired, take the form of the dep~h encoder illustrated in the Miller et al tape recorder patent. The digitized depth data is then transferred to the depth determination circuits 60 of Figure 1. In this Figure 19 case, the data could be transferred in parallel to the `~
circuits 60 thus eliminating the necessity of shift pulses and the shift pulse window.

It can thus be seen from the foregoing that new and improved methods and apparatus have been provided for recording well logging data. This has been accomplished by utilizing a cathode ray tube for recording such signals. ~ recording system has been shown and described which not only can record data as it is being deri~ed rom a well logging tool in a borehole, but can also record data being transmitted or received over a telemetry link as well as data which has been previously recorded on magnetic tape and then played back to the recorder. The recorder of ~he present invention can provide any desired pattern of ~cale and depth lines. Moreover, this recorder is able to produce any number of line and area coding patterns as desired to thereby enable easy identification of not only individual logs recorded on the recording medium, ~ut also parameters represented by the areas between certain selected logs. This coding can b~ conditional by allowi~g area coding only when these logs maintain certain selected relationships to one an-other. Moreover, good quality recordings can be obtained regardless of the rate of change of the signals to be recorded.
It should be pointed out here that the techniques of the present inventions could be used with other types of record-ing devices than the fiberoptic CRT shown here. For example, an electrostatic recorder could be used just as well. Such an electrostatic recorder would have a pluIality of~wire ends ~a~52~73 positioned transversely across a record medium. The proper wire end would be energized to produce a mark at the proper posltion.
While there has been described what is at present ~;
considered to be preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made in the instrument without departing from the invention, and it is, therefore, intended .
to cover all such changes and modifications as fall within the ;~ -true spirit and scope of the invention. .

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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED, ARE DEFINED AS FOLLOWS:

1. A method of recording or displaying data signals of the type representing well logging data as a function of depth on a recording or displaying medium wherein at least one writing signal is produced in response to at least one data signal and comprising the steps of directing energy at said record or display medium along a line substantially transverse to said medium to place images on said medium generating a coding pattern signal and combining said at least one writing signal with said coding pattern signal to control the level of said energy to produce a coding pattern between selected boundaries on said recording or displaying medium, at least one boundary being representative of said at least one data signal.

2. The method of claim 1 further comprising the steps of combining the two writing signals produced from two data signals with said coding pattern signal to produce a coding pattern between two selected boundaries on said record or display medium, said two selected boundaries being representative of said two data signals.

3. The method of claim 2 wherein said coding pattern is produced between said selected boundaries only when said data signals assume a predetermined amplitude relationship to one another.

4. The method of claim 1 wherein said energy is directed at said record or display medium during successive sweep intervals along said line transverse to said medium and that the level of said energy is controlled to determine the placement and linear extent of said images on said record or display medium to thereby produce said coding pattern between boundaries.

5. The method of claim 1 wherein at least one writing signal produced in response to at least one of said data signals operates to produce a boundary trace representing said data signal further comprising the step of combining one signal function-ally related to said data signal with said coding pattern signal and said writing signal to produce a coding pattern writing signal operating to cause said coding pattern to appear between said selected boundaries.

6. The method of claim 5 wherein a reset signal is produced at the end of each sweep interval and the step of gener-ating a coding pattern signal comprises the steps of producing digital signals controlling the sweeping operation of said energy on a record or display medium and combining at least one selected digital signal with said reset signal for each sweep to produce said coding pattern signal.

7. The method of claim 6 further wherein the step of producing digital signals comprises the steps of generating clock pulses, counting said clock pulses to produce said digital signals, converting said digital signals to an analog sweep signal adapted for sweeping said energy across said record or display medium.

8. The method of claim 7 further comprising the steps of producing scale line signals from said digital signals, and combining said scale line signals with said coding pattern and writing signals to additionally produce scale lines on said record or display medium.

9. Apparatus for recording or displaying well logging data, comprising:
(a) means for producing at least one well logging signal representative of at least one subsurface characteristic at various depth levels in a borehole;
(b) a recording or displaying medium;

(c) means adapted for repetitively sweeping energy across said medium;

(d) means responsive to said signal for producing writing signals;

(e) means for generating a coding pattern signal; and (f) means responsive to said coding pattern and writing signals for modulating said energy to produce a coding pattern on said medium between the recorded traces resulting from said writing signal and another selected location.

10. Apparatus according to claim 9 wherein said means for producing at least one well logging signal representative of a subsurface characteristic at various depth levels in a borehole produces at least two such signals;

said signal responsive means being responsive to selected samples of said well logging signals for producing at least two writing signals; and said means responsive to said coding pattern and writing signals produces a coding pattern between boundaries representative of said at least two writing signals.