1. No category

Nov. 25, 1952
J. A. KRUMHANSL ET AL
2,619,632
PULSE COMMUNICATION SYSTEM
Filed April 25, 1948
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FIG. I
INVENTORS
-
FIG. 2' A
JAMES A. KRUMHANSL
By GtENN H._ MILLER
l
ATTORNEY
Nov. 25, 1952
J. A. KRUMHANSL ET AL
2,519,632
PULSE COMMUNICATION SYSTEM
‘
Filed April 23, 1948
Sheets-Sheet 2
_
INVENTORS
JAMES A. KRUMHANSL
BY
GLENN H. MILI_~ER
MM.W
ATTORNEY
Nov. 25, 1952
J. A. KRUMHANSL ET AL
2,619,632
PULSE COMMUNICATION SYSTEM
Filed April 25, 1948
3 Sheets-Sheet 3
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INVENTORS
JAMES A. KRUMHANSL
BY- GLENN H. MILLER
W.
I
ATTORNEY
Patented Nov. 25., 1952
2,619,632
'
UNITED s'mrsi
7
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osric ,
2,619,632
PULSE ooMMUNIoA'rioN SYSTEM
James A. Krumh'ans'l, Norwood, R. ‘L, and Glenn
H. Miller, A'me's! Iowa, assignors to St‘roi‘nberge
Carlson Company, a corporation of New York
Application April 23, 1948, Serial N0. 22,804
9 Claims.
.
.
1
,
..
(Cl. v332-—1<i)
2
A‘further object citric invention is to provide
a systemof pulsegtime modulation having an ad:
ditional variable factor which may be changed at
_
This invention relates to a method "of and
means for coded pulse communication, and more
particularly to systems for such communication
random intervals during the transmission of
employing pulse=timemodulation in ‘a manner
which substantially ‘enhances the secrecy of
communication,
_
g
7
‘
g
_
Cl
of substantially constant amplitude and duration,
the time displacement of each pulse with respect
time ,_ modulation system as readily varied
10
..
X-
._
.
.
.
t
..
...
prqvisib'n Ojf ,ifhprwédnisan‘s. i013 nrbducing'a train
of time-modulated .?alsési which. are es?ri’cielly
pulse being varied directly in accordanceivith the
corresponding modulating voltage.‘ The time
displacement ofeach intelligence pulseneed‘ not
be ‘directly proportional ‘to’ the signal amplitude.
For example, so 'calledi‘fpuljse‘ period” modulation
intervals-i
.Ah addiijionalxobiect 0f the. invention is the
either to the preceding pulse or to a reference
adapted for use
15
pulse cornmunicationv systems.
_ In 'accordancevvith the present invention; there
is provided means _for ‘transmitting intelligence
‘by pulse-time‘ modulation; Means are provided
may be employed if desired. Such a modulation
for altering the sense of modulation of predeter
mined successive groups of transmitted pulses, an
system‘ is disclosed and claimed in copending ap
plication Serial No. 646,614, now abandonedéas
signed to the same assignee as the present inven- -
tion. In this system, the pulse spacing‘, during
moduiation Varies with bdththe'signal amplitude
Such
,.
vide ‘any arrangement for-altering the sense ‘of
modulation ofjthe transmitted-pulses in a pulse
Inthe ordinary pulse-‘time modulation ‘system,
intelligence is transmitted by a "series of pulses
‘and an exponential
function of' time.
'
4
intelligence.
Still another object of theuinvention is to pro
_
a
pulse-time modulation system does not provide
arrangement being provided v'vh'eirehy the num
ber of pulses i-neach group may readily be altered
during trans iss'iori. 'To secure ‘synchronization
between'th‘e coder'a-tthe transmitter and the de
coder at the receiver,‘ provision is made for the
25
transmission of a synchronizing pulse following '
displacement increases with increased signal am
plitude. In the case'- of negative sense transmis
sion, the pulse spacing decreases with increased
signal amplitude‘. Pulse-time modulation; in gen
eral, may be accomplished either with or Without
30
Ways if desired. For example; the last intelligence
pulse ineach group could have its duration or
amplitude altered; or thecarrier wave Within this
?xed- reference pulses.
c0 01
secrecy of communication, since a receiver cin
ploying' a conventional averaging detector will
yield‘the intelligence being‘ transmitted.
_
Pulse-time modulation may be accomplished
Such changeovers may he“ indicated in other
in two senses. If the sense is positive, the pulse
.'
p
I
p
pulse could be frequency modulated.
I
a Any desire‘dlarrangeinen't may bcjempmy'e'd to
A certain degree of secrecy may be achieved in
pulse-time medication systems by alternating the
coding of successive pulses between the positive
and negative senses. sucn an arrangement is
disclose‘d- and claimed 11?; depending application
each group of intelligence pulses. The synchron
i'ziing pulses serve to indicate a ‘changeover from
positive to negative coding sense, or vice versa,
40
the coder and the decoder together. ‘For
example, the pulsed output of the-coder may serve
to modulate o'r-covntrol a transmitter of ultrahigh
frequency energy, and ;a suitable receiver and
demodulator provided at the receiving- end. in
stead yofra» radio link, it withinthe scope of
the invention to‘. convey coded intelligence to a
serial No‘. 646515, now Pat. NO. 2,466,230 issued
remote point. over a wire line, a transmission line,
Aprils,- 1949, assigned to the same assignee as
the‘ present invention. An averagingcetecmrwi11
or a coaxial line;
Y
not respond to' this type of coding. If the' output
The above and other objects and features‘df
pulses‘ from the‘ receiver‘ are used to trigger a 45 the‘ inventionwill be better understood by refer
multivibrator circuit having two conditions of
ence to the" following description taken in con
static equilibrium; as ro'r' example an Eccles
Jcrdan circuit, and the output of this’ multi
v'ibrator is averaged, the transmittéd‘intel-ligénce
may be‘ obtained,
‘
v
It is a principal object of the present invention
to provide an improved pulse coinmu'r'iication
system.
nection With' the accompanying-- drawings, in
which. like components are designated by like
reference munera'ls and in which: I
50
Fig. 1v represents; in block form, a'co'der and
associated apparatus for use at the transmitting
end of a pulse communication system in accord
ance with the present ‘invention;
'
Another object of the: present invention‘ is to
‘Fig. 2 shovvsl graphically, to ‘a common“ time
provide a; communication system utilizing'pulse 55 base, the voltage wavelforin's developed at various
time-modulation.
_
'
Q
.
..
.
Still another‘obje'cit of the invention'is‘ .to'uti'lize
a: novel ‘form of pulse-time modulation ‘which pro‘
vides' a high‘. degree3 of :sécrecy'. with? relatively
simple, compact-and inexpensive apparatus‘.
points‘ in the coderof Fig. '1' ;
-
Fig‘. 315191 schematic diagramlof the portion of
the coder of Fig. 1 .re'pre’sentedthy‘ block I 3‘;
' I Fig; . .4‘
a‘. schematic - diagram of "the - dividing
circuit represented by‘ block I‘? of Fig‘. 1;
2,619,632
3
4
Fig. 5 represents, in block form, a decoder
adapted for use at the receiving end of a pulse
communication system in accordance with the
of the wave shape designating the time interval
during which electronic switch H is conductive
for the waveform represented by curve 3. In the
example chosen for illustration in Fig. 2, the
present invention; and
'
Fig. 6 shows graphically, to a common time
period of the signal wave (curve I) is % that of
the switching square wave represented by curve
base, certain of the voltage waveforms developed
in the decoder of Fig. 5.
In the drawings, the encircled reference nu
It will be understood, of course, that it is
within the scope of the present invention to vary
merals refer to the corresponding curves or waves
this ratio over a wide range either above or be
represented in Figs. 2 and 6. Reference will be 10 low unity.
made to these curves in the following description
Fig. 3 shows the schematic diagram of a por
as an aid to a better understanding of the opera
tion of the coder represented by unit I3 of Fig. 1.
tion of the present invention.
This unit comprises an electron discharge device
Referring now to Fig. 1, a modulating wave
2 i, which may be a triode vacuum tube having a
(curve l) is supplied from a suitable source of
cathode 22, a control electrode 23, and an an
modulating voltage (not shown) to a phase in
ode 2Ll. Cathode 22 may be grounded as shown.
verter til, the output of which comprises ?rst and
A network comprising a capacitor 25 shunted by
second waves (curves 2 and 3) which are in phase
a resistor 26 has one of its terminals connected
opposition. Phase inverter 10 is of conventional
to control electrode 23. The other terminal of
design and hence need not be described in greater
network 25-26 is connected to the common cath
detail.
ode 21 of an electron discharge device 28, which
The outputs from phase inverter 58 are sup
is preferably a vacuum tube comprising a pair of
plied to an electronic switch II. This switch,
triodes each having a relatively sharp cuto? char
likewise of conventional design, is arranged se
acteristic. Vacuum tube 28 may, for example, be
lectively to connect either of the two input volt
of the type 6J6. Cathode 27 of vacuum tube 28
ages to its output, the changeover from one in
is connected to ground through resistors 29 and
put voltage to the other, and vice versa, being
Si] in series.
controlled by the voltage supplied to electronic
Control electrode 3| of the left-hand portion
switch ll through the connection [2.
of vacuum tube 28 is connected through resistor
The output voltage from electronic switch ll 30 32 and capacitor 33 in series to a ?rst input termi
may, for example, have the waveform illustrated
nal 313. The second input terminal 35 is prefer
in Fig. 2 by curve 4 when a suitable control volt
ably connected directly to ground as shown. A
age is supplied through connection IE to the
resistor 36 is connected between the junction of
switch.
resistor 32 and capacitor 33 and the junction of
The output of electronic switch II is supplied 35 resistors 29 and 3B.
to a coder unit 13, which is a device adapted to
The anode 24 of vacuum tube 2| is connected
provide a train of pulses the relative spacing of
through a ?rst winding 3'! of a transformer 38 to
which
time Varies in accordance with the in
a suitable source of positive potential, as indi
put voltage. The output of unit l3 comprises a
cated at 39. .Anodes 48 and 4| of vacuum tube 28
series of pulses of substantially uniform ampli
are likewise connected to potential source 39.
tude and duration but, in general, of varying
The control electrode 32 of the right-hand por
spacing, and is supplied to a mixer unit M by
tion of vacuum tube 28 is connected through a
means of connection [5.
winding 43 of transformer 38 to the junction of
One output from mixer unit hi, supplied
resistors 29 and 30. A third Winding M of trans
through connection l6, corresponds in waveform
former 38 is connected between a ?rst output ter
to the signal on connection I5, and is supplied
minal I35 and ground. The other output termi
to a dividing circuit ll. Assuming that dividing
nal d6 is preferably grounded as shown.
circuit I? is arranged to divide by a factor of
In operation, a suitable input signal is supplied
three, for example, its output will have the wave
between input terminals 34 and 35. The left
form indicated by curve 5 in Fig. 2. This output
hand portion of vacuum tube 28 functions as a
wave is supplied by means of connection 12 to
cathode follower, so that the applied input sig
electronic switch II and is utilized for the pur
nal is effectively repeated between cathode 2‘! and
pose of throwing this switch after each group of
ground. This cathode voltage is applied, through
three successive pulses has passed through.
network 25-2 6, to control electrode 23 of vacuum
The output of dividing circuit l‘! is also sup
tube 2|. This vacuum tube, in combination with
plied to a delay circuit I8, the output of which in
transformer 38 and the right-hand portion of
turn serves to trip a synchronizing blocking os
vacuum tube 28 functioning as a cathode follower,
cillator G9. The output of unit l9 comprises a
operates as a blocking oscillator to produce a
series of pulses of the same periodicity as the
series of substantially rectangular output pulses
series represented by curve 5, but delayed with
between output terminals 45 and 46. The rate
respect thereto. These delayed synchronizing
at which these pulses are produced is a function
pulses are supplied by connection 28 to mixer
of the potential of control electrode 23 relative
to cathode 22, this potential in turn depending
unit M, in which they are combined with the sig
upon the amplitude of the voltage between cath
nal on connection 15. The resultant output wave
is represented by curve 6 of Fig. 2, and will be
ode 27 of vacuum tube 28 and ground and upon
the time constant of network 25 26.
seen to include a plurality of groups of three in
telligence pulses ‘I, of varying spacing, these
When the blocking oscillator fires, that is,
groups being interspersed by a series of synchro
vacuum tube 2| becomes conductive, control elec
nizing pulses 8 of substantially uniform spacing.
trode 42 of the right-hand portion of vacuum
Curve 9 of Fig. 2 is intended to represent graph
tube 28 is driven positive, so that this portion of
ically the operation of electronic switch H, the
this tube becomes highly conductive. The result
positive portions of this wave shape designat
ant current ?ow through the circuit including
ing the time interval during which switch ll
cathode 21 causes a substantial potential drop
functions to pass the waveform represented by
across resistor 29. This potential drop is of such
curve 2, for example, and the negative portion 75 polarity and of sufficient magnitude to render the
2,019,532
5
6
'left-hand'portion of vacuum tube 28 nonco'nduc
‘tive. In this manner, no appreciable signal volt
nected-through an adjustable resistance device 63
age is developed between cathode 21 and ground
during the ?ring portionof the cycle. As a result,
resistor
to control
64 iselectrode
connected
45’‘between
of vacuum
control
tubeelectrode
41.
electrode 6| , andaii'anode 62. Cathode 66 isccm
the magnitude of the signal voltage at input ter
6| of vacuum tube 59 ‘and a suitable source of
minals ‘3'4 and '35 can have no in?uence upon the
negative potential as indicated at '65. A. ?rst
input terminal ‘66 ‘is coupled to control electode 161
by
preferably’
capacitor
grounded
61. 1 Theasother
shown.
input
Anode
terminal
525's con
58.
amount of charge acquired by capacitor 25 due
to the flow of grid current in vacuum tube "2|
during thew-?ring portion of the cycle.
In other words, network 25-26 is e?ectively 1O nected to positive potential source 55.
_
always returned to a constant potential during
‘In operation, vacuum tube 41, in association
?ring, rather than having the potential of its
return point vary in accordance with the applied
signal voltage. By this arrangement, which is a
feature of the present invention, the time which
elapses between a first pulse and a second pulse
is made substantially independent of the magni
tude of the signal voltage which determined the
timing of the ?rst pulse.
When ?ring ceases upon control electrode 23
reaching a negative potential relative tocathode
22 well beyond cutoff, capacitor 25- gradually ‘dis
charges through resistor 26. Vacuum tube ‘2|
again becomes conductive as soon as the algebraic
sum of the potential across capacitor 25 and the
with transformer 53 and capacitor 5 I , operates as
a normally ‘biased-‘01f blocking oscillator. Each
time this oscillator ?res, a pulse of short dura
tion is produced betweenoutput terminals 51 and
58. Vacuum tube 5e~operatesas a cathode fol
lower to repeat at its cathode 60 positive-going
pulses which are applied between input ‘terminals
66 and 68. When such a pulse occurs, the poterr
tial of cathode 60 increases, and the resultant
current flow increases the charge of capacitor 5|.
During the interval between input pulses, vacuum
tube 59 is cut off, so that there is no appreciable
leakage current path through which the charge
on capacitor 5| may be dissipated. Thus control
electrode 49 of vacuum tube 41 is maintained at a
voltage of cathode 21 relative to ground makes
control electrode 23 less negative than its cu'to?
substantially ?xed potential following the cessa
value.
tion of each input pulse.
' ‘
In the meantime, control electrode 42 is no
The next input pulse causes a repetition of this
longer driven positive, so that the ‘right-hand 30 cycle of events, and adds to the charge on capaci
portion of vacuum tube 28 is no longer conductive
tor 5|, thus increasing the positive potential of
and there is no current l?ow through resistor 29
control electrode 49. When the latter potential,
due to this tube portion. The left-hand portion
after a seriesof input pulses, reaches a value
of vacuum tube 28 is thus rendered free to func
equal to or ‘exceeding the
potential of the
tion-as a cathode follower ‘to repeat at cathode 21 > blocking oscillator, the oscillator will fire to pro
the input signal applied to input terminals 34
duce a single output pulse between terminals '51
and 35.
_
-
and 58.
.
'
Still another method for solving the same prob
The magnitude of the current available‘ for
lem is to apply the signal voltage directly to the
charging. capacitor 5| due to each input pulse
control electrode 23 of the blocking oscillator 40 may be varied by adjusting variable resistance
tube 2|. The signal voltage source must be of
device 63. In this way, the dividing circuit may
high impedance in this case, so that it will not
be set to produce a single output pulse after a
appreciably effect the time constant of the
predetermined number‘of input pulses have oc~
blocking oscillator’ circuit, and its time constant
curred. The dividing factor is also dependent
must be very large compared with a pulse period
upon the negative potential of source 65, and
in order to prevent the superimposition of a 45 may be varied at will merely by applying a suite
charge on the control electrode.
able potential at this point. By changing the
Although described herein as applied to a
blocking oscillator, it will be understood that
these expedients may equally be well employed
in conjunction with other coding devices, as for
example multivibrators, delay multivibrators,
‘,‘squeggi-ng” oscillators, and thyratron relaxation
oscillators. ‘In each of these devices-as in the
blocking oscillator, the ?ring process produces a
dividing factor at more or less random intervals,
the secrecy of communication may be substani
tially enhanced. This is a feature of the present
invention.
‘
In the above-described coding process“, the
audio-frequency or other input signal voltage is
e?ectively added to a sawtooth voltage. When
the resultant sum attains a- certain value, a pulse
large current ?ow which is utilized "to give a 55 is produced. In this way, the period between
capacitor a certain charge.
pulses is made‘ a function’ of the input signal volt
Fig. 4 is the-schematic. diagram of a dividing
age. The decoding process is very nearly the eX-'
circuit such as that represented by block H in
act inverse of the coding process‘. Each’ received
Fig. I. This unit comprises an electron discharge
pulse initiates a sawtooth of predetermined‘ shape.
device 41, which may‘ be a triode vacuum» tube 60 and each sawtooth is terminated by the following
having a cathode 48, a control electrode 49, and
pulse. In this way, the amplitude to which the
an» ‘anode so. Cathode '48 may be grounded as
sawtooth rises is a function of the period between
shown. Control electrode “is connected through.
pulses and, by means of. a; sampling circuit and
a capacitor 5| to one terminal of a winding 52 of
?lter, a voltage corresponding to the input sig
transformer 531. The other terminal of winding 65 nal voltage is developed.
52?.may be grounded asshown.
7
Fig. 5 is a block diagram of one embodiment.
Anode 50 is connected through a winding 54
of a decoder in accordance with the present in»~
of transformer 53 to-a sourceof postii-ve potential,
vention. The input pulses, which comprise both.
as indicated at 55. The'term-inals of winding'56 70 intelligence and synchronizing pulses, are sup
of transiormer 5-8‘ are connected respectively to
plied to unit 10 comprising pulse separation cir
output‘termlnals 51 and 58.
‘
>
cuits. The function of unit 10 is tov distinguish
There is also provided ‘a second electron. dis~
and separate‘ thev intelligence pulses from the
.charge. device 59,,which may al'sommp?se a
’ synchronizing'pulses, and this
is of convene,
ode vacuum tube having a cathode 50, a control 75 tional design. For example, a pair of delay multi
2,619,632
.7
8
vibrators may be utilized. The second of these
delay multivibrators furnishes an output pulse
which, by virtue of its position in the time scale,
contains the intelligence originally carried by the
intelligence pulse fed into unit 10.
The intelligence pulse output from unit 10 is
supplied to a sawtooth generator ‘H.
Each in
cathode followers having a common cathode cir
cuit, said ?rst cathode follower having a control
electrode; a coupling loop between said anode
and said control electrode of said electron dis
charge device including said control electrode of
said cathode follower; a source of input signals;
means for applying said input signals to said con
telligence pulse resets the generator after its out
trol electrode of said electron discharge device
including said second cathode follower; and
ing between successive pulses. The intelligence 10 means for utilizing the output of said blocking
pulses from unit 10 are sufficiently long to in
oscillator.
sure the complete discharge of the capacitor in
2. In combination: a blocking oscillator com
put has reached a value dependent upon the spac
the saw-tooth generator ‘H, and so to provide a
prising an electron discharge device having a con
resetting period which extends appreciably be
trol electrode and an anode, and a multi-winding
yond the complete discharge time. The resultant 15 transformer; means connecting a ?rst winding of
sawtooth voltage wave is then passed through a
phase inverter 12, which supplies two output
waves in phase opposition to an electronic switch
13.
Switch 13 is triggered by synchronizing pulses
furnished from unit 10 by means of a connection
74. When the original input signal to the system
comprises a modulated wave and the sense of
coding is reversed after every three intelligence
pulses, the output wave from switch 13 hasthe
waveform indicated by curve 15 of Fig. 6.
This output wave is supplied to sampling circuit
16, which may be of the type disclosed and
claimed in copending application Serial No. 22,803
said transformer to said anode; ?rst and second
cathode followers having a common cathode cir
cuit, said ?rst cathode follower having a control
electrode; a coupling loop between said anode
and said control electrode of said electron dis
charge device, including said control electrode of
said cathode follower and, a second winding of
said transformer; a source of input signals;
means for applying said input signals to said
control electrode of said electron discharge device
including said second cathode follower; and
means including at third winding of said trans
former for utilizing the output of said blocking
oscillator.
3. In combination: a blocking oscillator com
?led April 23, 194.8, in the name of James A. 30
prising an electron discharge device having a
Krumhansl and assigned to the same assignee as
control electrode and an anode; ?rst and second
the present invention. Unit 16 is actuated from
cathode followers having a common cathode cir
unit 10 by means of a connection 11, in such a
cuit; a connection between said cathode circuit
manner that it stores the peak value of each saw
tooth wave before sawtooth generator ‘H is reset 35 and said control electrode; a coupling loop be
tween said anode and the input circuit of said
by the next intelligence pulse. The resultant out
?rst cathode follower; a source of input signals;
put of unit 16, therefore, is a step-function ap
a coupling between said source and the input cir
proximation of the original modulating signal, as
cuit of said second cathode follower; and means
indicated by curve 18 of Fig. 6. This wave is sup
plied to a low-pass ?lter unit 19, the resultant 40 for utilizing the output of said blocking oscilla
tor.
output of which, as shown by curve 80 of Fig. 6,
4. In combination: a blocking oscillator com
approximates the original modulating signal.
Any one of Figs. 1-3 of the above-mentioned co
pending application may be employed for sam
pling circuit '16. On each of these Figs. 1-3, wave
form 15 may be applied to signal input terminals
I1, [8; the connection 11 may be made to ter
minals 9, It; and the output waveform ‘[8 ob
tained between conductor 19 and ground (termi
nal I8).
'
If desired, sampling circuit 16 could be placed
ahead of phase inverter 12 and electronic switch
13, with substantially the same overall results.
prising an electron discharge device having a
control electrode and an anode, and a multi
winding transformer; means connecting a ?rst
winding of said transformer to said anode; first
and second cathode followers having a common
cathode circuit; a connection between said cath
ode circuit and said control electrode; a coupling
loop between said anode and the input circuit of
said ?rst cathode follower, said coupling including
a second winding of said transformer; a source of
input signals; a coupling between said source and
The sequence shown in Fig. 5 is preferable, how 55 the input circuit of said second cathode follower;
and means for utilizing the output of said block
ever, since it eliminates the undesired signal
ing oscillator.
which would otherwise be introduced due to the
5. In combination, a blocking oscillator hav
switching operation. This desirable result is
ing an input circuit; a source of modulating volt
realized in the arrangement of Fig. 5 because the
age; means applying said voltage to said input
sampling circuit remains closed during the 60 circuit to control the recurrence frequency of the
switching operation, and hence the system is un
output impulses of said oscillator; and means for
responsive thereto.
establishing a reference voltage in said input cir
While there has been described what is at
cuit at the termination of each cycle of the out
present considered the preferred embodiment of
put of said oscillator; ‘the last named means
the invention, it will be obvious to those skilled 65 comprising a source of said reference voltage,
in the art that various changes and modi?cations
means constituting a normally interrupted cou
may be made therein without departing from the
pling path between the last named source and
invention, and it is, therefore, aimed in the ap
said input circuit, and means utilizing the out
pended claims to cover all such changes and
put of said oscillator to complete said path dur
modi?cations as fall within the true spirit and 70 ing each impulse of said output.
scope of the invention.
6. In combination, a blocking oscillator hav
What is claimed is:
ing an input circuit, a source of modulating volt
1. In combination: a blocking oscillator com
age, means applying said voltage to said input
prising an electron discharge device having a
circuit to control the recurrence frequency of the
control electrode and an anode; ?rst and second 75 output impulses of said oscillator, and means for
2,619,632
establishing a reference voltage level in said in
put circuit, the last named means comprising a
10
control electrode, and a condenser connected to
said control electrode and having the output of
source of voltage of said reference level and a cir
cuit coupling said reference voltage source to
said tube coupled thereto whereby said con
denser is charged during the generation of an
said input circuit, said coupling circuit compris
output impulse by said oscillator; a source of
ing a normally non-conducting space discharge
modulating voltage; means, coupling said source
device and means applying the output of said os
to said condenser whereby the recurrence fre
cillator to said device to render it conducting
quency of the output impulses of said oscillator
during each impulse of said output.
becomes a function of said modulating voltage;
7. In combination, a blocking oscillator, a 10 and means establishing a reference voltage level
source of modulating voltage, means applying
at said condenser at the termination of each im
said voltage to the input of said oscillator to
pulse of the output of said oscillator, the last
control the recurrence frequency of the output
named means comprising an electric discharge
impulses thereof. a source of reference voltage,
device having an anode, a cathode and a control
means coupling said source of reference voltage
electrode, said anode being maintained at said
to the input of said oscillator, a switching means
reference voltage, said cathode being coupled to
normally interrupting said coupling means and
said condenser and said control electrode of said
means applying the output of said blocking oscil
device having coupled thereto the output of said
later to said switching means whereby said cou
oscillator, said device being non-conductive ex
pling means is completed during each impulse 20 cept during the impulses of the output of said
oscillator.
in the output of said oscillator.
JAMES A. KRUMHANSL.
8. In combination, a blocking oscillator, a
source of modulating voltage, means applying
GLENN H. MILLER.
said voltage to the input of said oscillator to con
REFERENCES CITED
trol the recurrence frequency of the output im
pulses thereof, a source of reference voltage,
The following references are of record in the
means coupling said source of reference voltage
?le of this patent:
to the input of said oscillator, said coupling
UNITED STATES PATENTS
means including the space discharge path of an
Number
Name
Date
electric discharge device having a, control elec
Re. 23,288
Krumhansl et a1. ____ Oct. 24, 1950
trode, and means applying the output of said os
2,266,401
Reeves __________ __ Dec. 16. 1941
cillator to said control electrode, whereby said
space discharge path is completed during each
impulse of the output of said oscillator.
9. A pulse-position modulated pulse generator 35
comprising in combination a blocking oscillator;
said oscillator including a vacuum tube having a
2,289,564
2,444,890
2,448,814
2,449,467
2,466,230
Wrathall ________ __ July 14,
Hite et a1. ________ __ July 6,
Mann et a1. ______ __ Sept. 7,
Goodall _________ __ Sept. 14,
Goldberg _________ .... Apr. 15,
1942
1948
1948
1948
1949