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Патент USA US2412963

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EQE.
P. K. CHATTERJEA ETAL
2,412,93
ARRANGEMENT FOR DETERMINING AND MONITORING THE
‘
DURATION OF ELECTRICAL PULSES
Filed June 12,1943
H64.
'
Patented Dec. 24, 1946 ~
"1:1 T.
2,412,963.
Al{RANGEMENTv FOR DETERIVIININGI- AND
MONITORING 'THE DURATION 'OF ELEC
TRICAL PULSES
Prafulla. Kumar Chatteriea,
Charles
Thomas '
Scully, and Dermot Min Ambrose, London, Eng- .
land, assignors to StandardTele'phones and
.
Cables Limited, London, England, a British
company .
_
Application June 12, 1943. Serial No. 490,574
. In Great Britain July 21, .1942
5 Claims. ' (Cl. 161-15)
.
1
2
.
Figure 1 is a diagram showing the circuit con
The‘ present invention relates to a method of
and arrangements for determining or monitoring
nections to the cathode ray tube.
-
' Methods of estimating pulse width normally.
Figure 2 shows the form of the pulses which are
to be measured and which are applied to the
employed are either direct measurement of the
vertical de?ector plates.v
\ the duration of electrical pulses.
pulse width as compared with the repetition time of the pulses on the screen of a cathode ray oscil
. l'oscope or by using an oscilloscope with a circular
'
Figure 3 shows the sine wave which is applied
to the horizontal de?ector plates. .
Figure 4 shows the composite trace which ap
, trace and applying ‘the pulse to the grid of the
pears on the screen of the tube.
cathode ray tube and so blanking out a section of 10
The circuit forxthe apparatus is shown in Fig. 1.
the trace during the pulse vperiod. Thus, if the
The cathode ray tube H with X~de?ector plates
speed of the circular sweep is known then the
l3 and Y-de?ector plates 15 is connected by any
' duration of theblanked out section may be de- ,
known means to a power supply,‘ not shown, in
'
termined.
.
>
such a manner as to produce a focussed spot on
15 the screen at S. One X-de?ector plate I3 is con
'
The ?rst of these methods cannot be used prac
tically when the pulse duration is small and/or
when therepetition time is small while the second
tends to become expensive in special apparatus.
‘
nected to an oscillation generator l'l, while ‘one
Y-de?ector plate I5 is connected via lead 19 to
the source of the pulses whose duration it is re- '
‘According to one aspect of the present inven
quired to determine.
~tion,_the method of determining the duration of 20
‘
-
v
The other X and Y plates are bonded to ground
or some. similar ?xed datum voltage level.
electrical pulses comprises generating oscilla
tions, comparing the oscillation period against
the pulse duration and varying the frequency of
plates while the sine wave oscillations from the
the generated oscillations until the oscillation
generator H are on the horizontal de?ector
The pulses are thus on the vertical de?ector
period is equal to the pulse duration,
25 plates. Figures such as are shown in Fig. 4 will
According to another aspect of the invention,
then be obtained under certain conditions as will
a method of determining the duration of electrir
now be described.
. 1 _
‘
cal pulses comprises generating oscillations hav
The explanation of the ?gures produced on the
ing a period equal to the pulse duration.
cathode-ray tube screen ‘when the frequency of
_
The method of monitoring the duration of elec 30 the oscillation generator is adjusted to have the
trical pulses according to the present invention
same period as the pulse duration will be given
comprises comparing the duration of said pulses
in conjunction with the Figures 2, 3 and/‘l.
against the period of oscillation of known con
Figures 2 and 3 represent the pulse l0 and the
stant frequency.
.
‘
'
From another aspect, the method of monitor
ing the duration of electrical pulses according to
.
. wave-form generated in I‘! respectively drawn to
the same time scales. Figure 4 shows the dia
gram as produced on the cathode-ray tube. (The
. the present invention comprises generating oscil
scales in this ?gure (Fig.4) ‘bear no reference to
the scales in Figures 2 and 3.)
to the desired pulse duration, comparing the pulse
At the start of a cycle point 2| the spot on the
duration against the oscillation period and ad 40 cathode ray tube is at point 2|’ and moves so
lusting the pulse duration until the said duration
that at 23' it coincides with’ point 23 in Fig. 3.
is equal to the said period. Y
'
, This is, with reference to Fig. 2, the start of the
lations of ?xed frequency whose period is equal
In the method described below the only appa-~ ~
ratusv required is a cathode ray tube which is
capable of producing a spot on the screen and an
oscillation generator of variable frequency su?l
-cient to cover the frequency of period equal’ to
'. the duration of the pulse. For instance, if the
rise of the pulse which continues its rise to point
25 when the spot has now travelled verticallyto
point 25'. From here the spot performs almost a
.quarter of a cycle to point 27' corresponding to
21 and from thence over a half cycle to 29" and
_ a further quarter cycle to point 3 l ' corresponding
- pulse duration is X micro-seconds the frequency
to point 31. Thus. from point 25' to 3|’ which is
‘ having this period would be
50 practically a complete cycle the spot has no
I
1
_E
x><10”°_ x
“cycles/second and the oscillation generator would
7 have to be capable of producing this ‘frequency,
change in its vertical de?ection,
-. .At point it’ and 3| the end of the pulse is
reached and the spot falls to point 33' corre
sponding to 33 and travels to point 35' thus cour
55 pleting a cycle and one half from point 2| '. Un- _
2,419,988,
3"
4
-
' til the next pulse occurs the spot now oscillates ’
between points 2|’ and 35" with no change in its
vertical de?ection.
' ,
'
means for adjusting the frequency of said sinusoidal electrical waves.
,.
2. Method of determining the duration of the
pulses .of a source of rectangular voltage pulses
by means of a cathode ray oscillograph having
,
. It is to be noted that between points 23 and 3|
or 25 and 33 one complete cycle is traced. Thus
when the ?gure on the screen is adjusted so that
means for producing a cathode ray beam, per~
Y the two vertical lines 23' to 25' and 3|’ to 33' as
pendicularly related ?rst and second de?ection
nearly as possible coincide the duration of the
' elements and a ?uorescent screen, which com
pulse is the same as the duration of one cycle of
prises impressing said rectangular voltage pulses
vthe. generated wave in Fig. 3. Thus if the fre 10 on said ?rst de?ection elements, impressing sinus
quency of the wave in Fig. 3 is )‘ cycles/second the
oidal electrical waves of a ‘predetermined pe
duration of the pulse‘is-v
riodlcity from another source on said second de
?ection elements and determining the duration of
said rectangular pulses by adjusting the perio
15 dicity of said sinusoidal electrical waves until the
form of the luminous trace produced on said
?uorescent screen coincides with a. predetermined
seconds or
' .12
_
micro-seconds.
pattern.
f
‘
i
.
the centre of the traces 29', 21'_ and 2|’, 35' but
may occur anywhere along these lines dependent
,. forms.
The result is not affected by this move
-'
.
thepulses from a source of rectangular voltage
pulses'by means of a cathode ray oscillograph
having means for producing a cathode ray beam,
The vertical line' 31 which is composed of the
two traces 23', 25’ and 3|’, 33' may not appear in
upon the phase relationship of the two wave
.
3; The method of determining the duration of
perpendicularly related ?rst and second de?ec—
tion elements, and a ?uorescent screen which
applying said pulses from said source
2.5 comprises
to said ?rst de?ection elements whereby the volt
ment so long as the two vertical traces coincide.
'_ To facilitate the initial. adjustment of'these
?gures obtained on the cathode ray tube screen
it may be found desirable to apply the pulses as a
small synchronising signal to the oscillation gen 30
age changes at the leading and trailing edgesof
each pulse will produce traces across said ?uo
rescent screen, applying a sinusoidal voltage to
said second de?ection elements, adjusting the
erator'by any known arrangements but should
afterwards be removed as the synchronisingwill
tend to change the frequency of the generated
periodicity‘ of said voltage until said traces co
‘pulses having a predetermined frequency com--'
prising a cathode raytube oscillograph, means for
5. Means for determining the duration of rec
tangular electrical pulses comprising a, cathode
' focussing the cathode beam on the ?uorescent
I screen thereof, two pairs of perpendicularly re
and a source of sinusoidal electrical signals, means
incide, and thereafter determining the pulse dura
tionby the frequency of said sinusoidal voltage.
4.'Means for determining the duration of rec
wave to a slight extent.
_
'
'
Besides using these arrangements for measur 35 tangular electrical pulses having a predetermined
frequency, comprising a cathode ray oscillograph
- ing pulse duration, .they may also be used to
having sets of de?ection plates, and a source of
monitor a pulse whose duration is desired to be
sinusoidal electrical signals, means for applying
. kept constant. In this case'the generated oscilla
the predetermined sinusoidal electrical signals to
tion is ?xed at the frequency, having the, period
of the required pulseduration and the pulse. width 40 one set of de?ection plates, means for applying
the rectangular electrical pulses to another set of
altered to make the lines 23’, 25' and 3|’, 33’. Fig.
de?ection plates, and means for adjusting the fre
4 coincide. ‘
.
‘
quency of the sinusoidal electrical signals whereby
What is claimed is:
a trace coinciding with a predetermined pattern is
r 1. Apparatus for determining the duration of‘
obtained.
the pulses of a source of rectangular voltage
ray oscillo'graph having sets of de?ection plates
lated de?ection elements, a, source of sinusoidal 50 for applying the sinusoidal electrical signals to
one set of de?ection plates, means for applying
electrical waves of a predetermined frequency,‘
the rectangular electrical pulses to another set of
.means for- applying said source of rectangular
de?ection plates, and means for adjusting said
voltage pulses to one pair of said de?ection ele
rectangular electrical pulse width independently
ments, means for applying said sinusoidal elec
trical waves to said other pair of de?ection ele- ‘ of the sinusoidal electrical ‘signals to produce a
trace coinciding with a, predetermined pattern.
ments, and means for comparing the width of
PRAFULLA KUMAR CHA'I‘TERJEA.
said rectangular voltage pulses with the frequency .
CHARLES THOMAS SCULLY.
of said sinusoidal electrical waves comprising
DERMOT MIN AMBROSE.
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