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Патент USA US3034059

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May 8, 1962
3,034,049
_1. w. DOWNS
MUZZLE VELOCITY CHRONOGRAPH
2 Sheets-Sheet '1
Filed March 16, 1955
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FROM
DELAY STÄRT
GHTE' 30
TIITEI
May 8, 1962
3,034,049
J. w. DOWNS
MUZZLE VELOCITY CHRONOGRAPH
Filed March 16, 1955
2 Sheets-Sheet 2
ì. ,va/,sf ---|
A IIÈWWMIHIIIIIllllIlllllIIIIIIIHIIIIIIIIIIIIHI
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I
INVENTOR
- dof/N Vl/.ßo w/vs
BY
Ta 6,475 .50
/ä//áßßaé
ATTORNEY
tice
Y 3,034,049
Fatented May 8, i962
Z
3,034,049
MUZZLE VELGCÍTY CHRONOGRAPH
John W. Downs, Glen Cove, N.Y., assigner to Sperry
Rand Corporation, a corporation of Delaware
Filed Mar. 16, 1955, Ser. No. 494,782
15 Claims. (Cl. 324-70)
This invention relates to a Doppler-type chronograph
directional counter through a pulse divider circuit, which
divides the number of pulses according to the ratio
T1/ T2.
The pulse source is also connected to the decimal
counter. When the bidirectional counter is brought back'-
to its zero condition, it cuts oft thecorrective pulses from
the pulse source to the decimal counter. The resulting
indication on the decimal counter is the true muzzle
velocity.
For a better understanding of the invention, reference
is concerned with a chronograph including a computer 10 should be had to the accompanying drawings, wherein:
for measuring projectile velocities, and, more particularly,
for giving true muzzle velocity of an artillery piece.
In application S.N. 250,887, filed on October ll, 1951, in
the name of John W. Downs, and now Patent No. 2,751,
593, there is described a Doppler-type chronograph which
FIG. 1 is a block diagram of a complete chronograph
circuit including the computer;
.
_
FlG. 2 is a block diagram of the component- parts of
the programming circuit of FIG. l;
FIG. 3 is a graphical representation ofthe wave shapes
measures the velocity of a projectile a predetermined 15
at various stages of the programmingcircuit of FiG. 2;
time interval after it is ûred from a gun. The reason for
delaying the velocity measurement is to permit the ñash
gases to dissipate, since the flash gases obscure the pro
FIG. 4 is a graphical representation of projectile
velocity as a function of time, with the timing intervals
superimposed; and
.
jectile, preventing the reflection of the Doppler radar sig
nal by the projectile. While the chronograph therein 20 FIG. 5 is a schematic diagram of a portion of the
computer.
described is highly satisfactory in operation and gives
With particular reference to the `form of the invention.
extremely accurate velocity measurements, the resulting
illuustrated in FIG. l, the numeral 10 indicates generally
measurement is not a true muzzle velocity but is the
a high frequency radio transmitter, the youtput of which
velocity measured at some distance from the gun. Since
all gun sighting computers are set up to receive velocity 25 is coupled to an antenna 12. The transmitter is prefer
ably designed to generate a carrier signal having a fre- 7
information in the form of muzzle velocity, it is neces
quency of 10,000 megacycles. The transmitting antenna
sary to apply a correcting factor to the velocity readings
12 is so positioned relative to a gun (not shown) Whose
obtained from the chronograph described in the above
muzzle velocity is being measured that as a projectile 14
mentioned copending application. The correction to be
added, however, depends on many factors including the 30 emerges from the gun, the transmitted signal is reflected
therefrom back to a receiving antenna le. The transmit
Weight of the projectile, the size and form of the pro
ting antenna l2 and receiving antenna 16 are preferably
jectile, the propellant used, the density of the air, the
temperature of the air, and the elevation of the gun.
If the correction factor were computed and tabulated
mounted adjacent each other.
`
would be complex, bulky, and a nuisance to use.
It is the general object of this invention to avoid and
received atthe antenna 16 is of a frequency of 10,00()
- fd megacycles, where fd is the Doppler frequency shift.
Doppler-type chronograph which measures the projectile
manner characteristic of the superheterodyne-type re
The frequency of the reflected signal is shifted in ac
for a number of different guns for varying conditions of 35 cordance With the Doppler principle by an amount pro
portional to the velocity of the projectile 14. The signal
the above factors, it is evident that the tabulated data
In addition, there isY a small leakage signal of 10,000
overcome the foregoing and other diiiiculties of and ob
jections to the prior art practices by the provision of an 40 megacycles from the transmitting antenna 12 at the
receiving antenna 16.
improved Doppler chronograph which indicates the true
The signal at the receiving antenna is mixed with a
muzzle velocity of the projectile of any gun regardless
signal of 9,966 megacycles from a local oscillator 17.
of the above-enumerated factors affecting the trajectory
The receiver input signal and the local oscillator signal
of the projectile.
‘
Another object of this invention is the provision of a 45 are heterodyned in the mixer circuit 18 in conventional
ceiver to produce an intermediate frequency having a
velocity after a period of time sufficient to permit the
34 megacycle component, a 34-j-fd megacycle compo
dissipation of the ñash gases.
nent, and a 34-fd megacycle component. It will be‘
Another object of this invention is to provide a chrono
graph including a computer which automatically com 50 appreciated that the intermediate frequency signal is es
sentially a carrier signal of 34 megacycles modulated by
putes the muzzle velocity from velocity measurements
the Doppler frequency of fd. The intermediate frequency `
taken at ñxed time intervals after the tiring of the gun.
signal is amplified by suitable amplifying means 2€) and
These and other objects of the invention which will
applied to an amplitude modulation detector 22, the out- `
become apparent as the description proceeds are achieved
by the provision of apparatus including transmitter-re 575 put signal of which is the Doppler signal having a fre- quencv of fd.
ceiver means for producing a train of Doppler pulses at
The Doppler signal at the output of the detector 22 is
a repetition frequency proportional to the projectile
amplified at 23 and applied to a band pass ñlter 24 de
velocity. The Doppler pulses are gated during a fixed
signed to pass frequencies of the order of 38 to 84 kilo
time interval to a decimal counter, the center of the
ñrst interval occurring at a predetermined time interval 60 cycles and to reduce spurious noise signals outside this
frequency range, thus eliminating Doppler cycles due to
T1 after the gun is ñred. During the same fixed interval
moving objects other than the projectile and also sup
the Doppler pulses are also gated to a bidirectional
pressing inherent noise pulses. A filtered sine wave
counter. The Doppler pulses are gated during a second
signal is then shaped into pulses by means of a shaping
time interval to the reverse count input of the bidirectional
Ycircuit 26 to trigger a computer indicated generally at 28. Y
counter, the center of this second interval occuring at 65
The output from the shaping circuit 26 is shown in
a predetermined time interval T2 after the gun is iired.
FIG. 3A. When the gun is fired, initially some ten or
The resulting count on the bidirectional counter after
fifteen Doppler pulses are produced before the signal is
the second interval is equal to the difference between the
obscured by the llash gases. The period during which
number of Doppler pulses, i.e., the velocity, during the
the flash gases are emerging from the gun barrel lasts for
ñrst interval, and the number of Doppler pulses, i.e., 70 a period of time depending 0n the size of the gun. ` For
the velocity, during the second interval. A pulse source
is then coupled to the reverse count input of the bi
example, a 120 millimeter gun is found to have a ñash
gas dissipation time of approximately .20 second, while
3,034,049
4
a 90 millimeter gun has a flash period of .l5 second.
During this interval only a noise signal is present at the
receiver antenna and no Doppler pulses are produced.
After the flash gases have dissipated the Doppler pulses
are continuously produced until the projectile passes out
of the range ofthe Doppler radar.
The initial ten or fifteen Doppler pulses are not suñi
cient to make a velocity measurement, so that a delay
must be introduced before a velocity measurement is made
bidirectional counter 44. Thus at time t2, corresponding
to the end of the ñrst pedestal pulse of FIG. 3D from
the programing circuit 32, a count is established on the
decimal counter 38 and on the bidirectional counter 44
corresponding to the average velocity of the projectile
during the time interval t2-t1.
At the time t2, the programing circuit puts out a
pulse, as shown in FlG. 3E, which is coupled to the elec
tronic switch 36 and the electronic switch 42.
At a re
However, the 10 sult the electronic switch 42 then couples the output of
the gate 40 to the reverse count input of the bidirectional
initial ten or fifteen Doppler pulses are used to trigger the
to permit dissipation of the íìash gases.
computer 23 by means of a delay start gate 30 connected
counter 44.
At a time t3, the programing circuit 32 puts
out a second pedestal pulse of the same time duration as
to the output of the shaping circuit 26. The delay start
the tirst pedestal pulse, as shown in FIG. 3F, which is
gate 30 comprises a step-type integrating circuit, prefer
ably of the type described in the above-mentioned co 15 coupled to the gate 40. `A second group of Doppler
pulses are passed by the gate 40 from the shaping circuit
pending application. Only ten pulses of the frequency
26 to the reverse count input of the bidirectional counter
and amplitude of the Doppler pulses from the shaping
44. At a time t4, corresponding to the end of the sec
circuit will trigger the integrating-type counter or" the
ond pedestal pulse, the gate 40 is closed and the count
delay start gate 30. However, random noise pulses will
not actuate the delay start gate 30. Thus it acts to in
sure that the computer will not be prematurely triggered
by periodic noise pulses or other transient signals.
On receiving at least ten Doppler pulses from the shap
ing circuit 26, the delay start gate 30 triggers on a pro
on the bidirectional counter 44 is equal to the ditference
between the number of Doppler pulses occurring during
the ñrst pedestal pulse from time t1 to t2 and the number
of Doppler pulses occurring during the second pedestal
pulse from time t3 to t4.
A source of correcting pulses, indicated at 46, is pro
graming circuit 32. The programing circuit, shown
vided in the computer 2S, the output from the pulse source
in FIG. 2 and to be hereinafter more fully described,
46 being connected through a relay 43 and a gate 50 in
controls the sequence of operations of the computer 28.
series, and through the electronic switch 36 to the deci
The various outputs of the programing circuit 32 are
mal counter 38. The gate S0 is opened by the program
shown in FIGS. 3D-G. When triggered by the delay
start gate 30, the programing circuit 32 puts out a pedes~ 30 ing circuit 32 at time t4, as indicated in FIG. 3G. The
relay 48 is actuated by the bidirectional counter 44, in
tal pulse starting at time l1, the elapsed interval of time
a manner hereinafter to be more fully described, such
being suñicient to permit dissipation of the flash gases.
that the relay 48 is open-circuited whenever the bidirec
The pedestal pulse is shown in FIG. 3D and is coupled
tional counter 44 is in its zero condition. However, when
to a gate 34 which passes Doppler pulses from the shaping
circuit 26 for the duration of the pedestal pulse from the 35 any count exists on the bidirectional counter 44, the relay
programing circuit 32.
The Doppler pulses passed by the gate 34 are coupled
48 is closed, passing correction pulses from the pulse
source 46 to the gate 50. Thus at the end of the second
pedestal pulse with a difference count existing on the
bidirectional counter 44, the relay 43 passes pulses vfrom
which counts the number of Doppler pulses during the
interval the gate 34 is open. The decimal counter is of 40 the pulse source 46 through the now open gate S0 to the
electronic switch 36 which has been triggered by the
conventional high speed counter design, such as described
programing circuit 32, as mentioned above, to pass the
in Patent No. 2,547,434, capable of counting rates up to
correcting pulses to the decimal counter 38.
100,000 counts a second.
At the same time the correcting pulses passed by the
The relationship between the velocity of a moving ob
gate 50 are coupled to an adjustable pulse divider 52
ject and the change in frequency of the reñected signal
which puts out pulses in any desired fractional ratio to
is given by the expression
through an electronic switch 36 to a decimal counter 3S
the number of input pulses.
C
(1)
A suitable circuit which
can be used as such a divider is the conventional ring
counter circuit, or the well known shifting register type
circuit. The output of the divider 52 is coupled to the
where c is the velocity of propagation and f is the fre 50 diiîerence counter 44, the output pulses from the divider
quency of the transmitted signal. Since the velocity of
52 triggering the bidirectional counter 44 to reduce its
propagation of a wave in space is 9836x105 feet per
count back to zero and close the relay 48.
As .will here
inafter be more fully appreciated, by making the ratio
second, and the transmitter frequency is 10,000 mega
cycles per second, the velocity may be expressed as 55 of counts produced by the divider 52 equal to the ratio
v=.049l8fd feet per second. Thus by counting the Dop
pler cycles during a time interval of .04918 second, the
¿2
'number of cycles counted is directly equal to the average
tri- 2
velocity of the projectile in feet per second during this
interval. The pedestal pulse put out by the programing 60
circuit 32 is accurately controlled to have a duration of
.04918 second, so that the figure appearing on the deci
mal counter is the average velocity of the projectile in
feet per second. The chronograph apparatus thus far
described is substantially identical to that described in
the resulting count on the decimal counter 33 is made
equal to the initial velocity of the projectile in .feet per
second.
the above-mentioned copending application.
The operation of the computer can best be understood
by reference to FIG. 4 which shows a graphical plot of
the velocity of the projectile as a function of time. The
projectile starts out with initial velocity of V0. At the
switch 42 to a bidirectional or diiîerence counter 44. A
70 end of an interval T1 its velocity has dropped to a value
suitable bidirectional counter is described in Patent No.
V1 and at the end of a second interval T2 its velocity
2,656,460 and includes two inputs one producing a for
has dropped to a value V2. It will be apparent that if
The programing circuit 32 also couples the initial
pedestal pulse to a second gate 40 which passes Doppler
pulses from the shaping circuit 26 through an electronic
ward count and the other producing a reverse count.
the change in velocity over the combined periods Trl-T2
The electronic switch 42 is initially set to pass the Dop
is substantially linear then the amount that must be added
to the velocity V1 to get the initial velocity V0, an amountI
pler pulses from the gate 40 to the forward input of the
3,034,049
5
designated X, will be given by the proportionality equa
tion
6
The multivibrator ’601, when it is triggered to itsV initial
condition by the output from the divider 56 passes an
output pulse, as shown in FIG. 3E along to a second
(2)
multivibrator 62 and also to the electronic switches 36 .
and 42, changing the condition of the electronic switches
where AV is the change in the velocity from V1 to V2.
In the computer as described above, the value of V1
in the manner above described. The multivibrator 62
on being returned `to its initial Ycondition by the next
in feet per second is recorded on the decimal counter
pulse out from the divider 56 triggers a third multivbratory
64, changing its stable condition. One Side of the multi
during the interval from t1 to t2. As indicated in FIG.
4, the average velocity V1 occurs at the center of this
interval, corresponding to the indicated time interval T1
after the gun is tired. The value of V1 is also recorded
on the bidirectional counter 44 during the interval from
t1 to z2 with the reverse count corresponding to V2 being
applied during the interval from t3 to t4, giving a net count
equal to AV on the bidirectional counter.
n
vibrator E6ft is connected to the gate 4t) so as to open
the gate 4t! when triggered from the multivibrator 62.
The next output pulse from the divider 56 triggers the
multivibrator 64 back to its initial condition, closing the
gate 40. The output Waveform of the multivibrator 64
to the gate 40 is shown in FIG. 3F.
The multivibrator 64 in turn is coupled to a fourth
`Correcting pulses are then applied through the divider
multivibrator 66, changing its stable condition. One side
$2 to the bidirectional counter 44. It will be appreci
ated from Equation 2 above that, if the divider 52 pro
duces output pulses in the ratio to input pulses of T2 to
T1, then when AV corrective pulses have been coupled
to the bidirectional counter 44, returning it to zero, the
number of corrective counts added to the decimal counter
38 will be equal to the quantity X, so that the final count
of the multivibrator 66 is connected to the gate Sit, so
that when the multivibrator 66 is triggered from the
multivibrator 64, the gate 50 is opened. The output of
on the decimal counter will be equal to V1+X, or the
the multivibrator 66 is shown in FIG, 3G. The multi
vibrator 66 is returned to its initial condition by appro
priate reset means, utilized in conventional manner to
reset all of the various multivibrator stages throughout
the various circuits of the computer before a subsequent
muzzle velocity V0 of the gun.
rcading’is made.
The programing circuit 32 is shown in more detail
in FIG. 2 and includes a crystal oscillator 54 having a
nominal frequency of 100 kc., for example, the output
of the oscillator being coupled to a frequency divider
circuit 56. The divider 56 preferably includes tive free
running type blocking oscillator stages having natural
frequencies of 50 kc., l0 kc., 2 kc., 460 cycles and 80
cycles per second, respectively. Each stage is synchro
nized by the previous stage with the input stage being
controlled by the crystal oscillator. Two additional
binary stages reduce the frequency to 4() and 20 cycles
per second respectively, giving a time period for one
cycle of nominally .05 second at the output of the di
vider 56. Actually, the frequency of the crystal oscil- ~
lator is set to give a time period of the desired .04918
second at the output of the divider 56. The waveform
of the output of the divider 55 is shown in FIG. 3B.
The divider 56 is biased into operating condition by the
‘
All of the circuits shown in block form in FIGS. 1
and 2 as above describedV are Well known in the digital
computer art.
The relay 48 is preferably a push-pull
type of relay as shown in FIG. 5. The relay coils
are preferably connected to the bidirectional counter 44
as shown. The bidirectional counter includes a plurality
of binary stages each n.including a pair ofV triodes or
pentodes having their cathodes connected to ground.
The counter may be modified for the present invention
such that the’cathodes of each of the tubes of the cor
responding side of each binary stage are connected to
gether to one coil of the push-pull relay and the cath
odes of the other side of each binary stage are con
nected together to the other coil of the push-pull relay.
In the zero condition for the bidirectional counter one
side of each binary stage is conducting, putting -a maxi
mum current through one of the coils of the push-pull
relay and a minimum current through the other coil
input from the delay start gate 39, in the manner more
of the push-pull relay, holding the relay in one posi
fully described in the above-mentioned copending appli
tion. -As soon as a count is established on the bidi->
rectional counter the amount of current through the one
coil will be reduced by at least the current through the
tube of one stage while the current in the other coil
will be increased by at least the same amount. Any
such incremental change in the current through the two
coils is suñicient to actuate the relay, completing the
circuit between the pulse source 46 and the gate 50.
From the above description, it will be seen’that the
various objects of the invention have been achieved by
cation.
The output from the divider 56 is coupled to an adjust
able divider 58, which preferably is a four-stage binary
counter. Each stage is a conventional bistable multi
vibrator circuit including two triodes which alternately
conduct and are capable of producing an output pulse
for each two pulses applied to the input. In the fourth
stage, however, the input is applied to only one of the
grids so that successive pulses into the fourth stage do f
not cause the two triodes to alternately conduct. The
result is a single output pulse regardless of the number
of input pulses, provided the initial conductive condition
is properly established. Although a maximum time delay
of .40 second or one pulse out for every eight pulses in,
is possible, a shorter delay period is achieved in conven
tional manner by changing the initial conducting arrange
ment of the counter stages. FIG. 3C shows the output
waveform of the divider 58 when it is set for a .20 second
time delay, which is one pulse out after four pulses in,
The output of the adjustable divider 58 is coupled to
a bistable multivibrator 60, the output pulse from the
divider 5S triggering the multivibrator 60 to one of its
stable conditions. One side of the multivibrator 60 is
connected to the gates 34 and 40. The next pulse from
the divider 56 following the output from the divider 58
is coupled to the multivibrator 60‘ returning it to its ini
tial condition and closing the gates 34 and 40. The
output from the multivibrator 60 is the pedestal pulse
shown in FIG. 3D.
the provision of a Doppler radar chronograph for
measuring the muzzle velocity of a projectile. Although
actual Velocity measurements are taken .at points in the
trajectory remote from the gun, the computer circuit
automatically converts the actual velocity measurements
to muzzle velocity. The computer can be readily set to
operate with a wide variety of guns by proper setting
of the two dividers, namely, the dividers 52 and 58,
which may be linked for simultaneous setting Vfrom a
single control. Where the Vflash dissipation time is rela
tively short, a one-to-one ratio of T1 to T2 can be used,
in which case the divider 52 is by-passed. It is desir
able for the sake of accuracy that the ratio be kept as
¿near unity as possible, within the limits imposed by the
range of the radar, the ñash dissipation time, and linearity
of the trajectory within the total measuring time.
Since many changes could be made in the above con
struction and many widely different embodiments of this
invention could be "made without departing from the
scope-thereof, it is intended that all matter contained in
3,034,049
l7
the above description or shown in the accompanying
drawings shall be interpreted as illustrative and not in
of clock pulses after the gun is fired, the first and third
gates passing Doppler pulses for a fixed time interval,
a limiting sense.
means actuated in response to the clock pulse source for
opening the third gate again a predetermined number
of clock pulses after the first opening of the third gate,
the third gate passing Doppler pulses for a fixed time
What is claimed is:
1. A Doppler chronograph for measuring the muzzle
velocity of a projectile, comprising means for transmit
ting and receiving a continuous microwave signal, means
coupled to the receiver for generating a series of Dop
interval, means actuated in response to the clock pulse
source for opening the second gate with the second clos
ing of the third gate, first switching means for selectively
connecting the counting means to the output from the
first gate and output of the second gate, second switch
ing means selectively coupling the output of the third
gate to the forward input of the bidirectional counter
and the reverse input of the bidirectional counter, and
means for actuating the first and second switching means
following the first opening of the first and second gates.
3. A .Doppler chronograph for measuring the muzzle
velocity of a projectile, comprising means for transmitting
pler pulses at a repetition frequency proportional to
the difference frequency between the transmited and re
ceived microwave signals, a high speed decimal counter,
a first gate coupling the Doppler pulses to the decimal
counter, a bidirectional counter including a forward count
input and a reverse count input, a pulse source, a sec
ond gate coupling the output of the pulse source to the
decimal counter, a third gate coupling the Doppler
pulses to the forward count input of the bidirectional
counter, a relay in series with the second gate for in
and receiving a continuous microwave signal, means
terrupting the iiow of pulses from the pulse source to
the decimal counter, means for :actuating the relay in 20 coupled to the receiver for generating a series of Doppler
puises at a repetition frequency proportional to the dif
response to the zero count condition of the bidirec
ference frequency between the transmitted and received
tional counter, whereby the flow o-f pulses to the decimal
microwave signals, counting >means, a bidirectional
counter is interrupted when the bidirectional counter
counter including a forward count input and a reverse
is in the zero condition, a divider coupled to the pulse
source through the second gate and the relay, the out
count input, a pulse source, a clock pulse source triggered
in response to the tiring of the projectile, means actuated
in response to a first predetermined number of clock
put of the divider being coupled to the reverse input of
the bidirectional counter, the divider producing output
pulses at a predetermined ratio in number of pulses to
pulses for coupling the Doppler pulses simultaneously to
the counting means and the forward count input of the
the input pulses, a source of clock pulses including a
bidirectional counter during an interval bet-Ween succes
30
crystal-controlled oscillator, means actuated in response
sive clock pulses, means actuated in response to a second
to the clock pulse source for opening the first and third
predetermined number of clock pulses for coupling the
gates simultaneously a predetermined number of clock
Doppler pulses to the reverse count input of the bidirec
-pulses after the gun is fired, the first and third gates pass
tional counter during an interval between successive clock
ing Doppler pulses for a fixed time interval, means
pulses, means including a divider for coupling pulses from
35
actuated in response to the clock pulse source for open
said pulse source to the countingv means and the reverse
ing the third gate again a predetermined number of
input of the bidirectional counter in a predetermined
clock pulses after the iirst opening of the third gate, the
ratio, and means coupled to the bidirectional counter for
third gate passing Doppler pulses for a fixed time inter
interrupting the output of said pulse source in response
val, means actuated in response to the clock pulse source
to a zero condition on said bidirectional counter.
for opening the second gate with the second closing of
the third gate, first switching means for selectively con
necting the decimal counter to the output from the first
gate and output of the second gate, second switching
means selectively coupling the output of the third gate to
the forward input of the bidirectional counter and the
4. A Doppler chronograph for measuring the muzzle
velocity of a projectile, comprising means for transmitting
and receiving a continuous microwave signal, means
coupled to the receiver for generating a series of Doppler
pulses at a repetition frequency proportional to the dif
ference frequency between the transmitted and received
microwave signals, counting means, a bidirectional
reverse input of the bidirectional counter, and means
for actuating the first and second switching means fol
counter including a forward count input and a reverse
lowing the first opening of the first and second gates.
2. A Doppler chronograph for measuring the muzzle
count input, means for producing a first train of pulses,
means for producing a second train of pulses, the number
velocity of a projectile, comprising means for transmit 50 of pulses during a given interval occurring in the second
ting and receiving a continuous microwave signal, means
train of local pulses being in fixed predetermined ratio
coupled to the receiver for generating .a series of Doppler
to the number of pulses during said given interval occur
pulses at a repetition frequency proportional to the dif
ring in the first train of local pulses, a clock pulse source
ference frequency between the transmitted and received
triggered in response to the firing of the projectile, means
55
microwave signals, counting means, a first gate coupling
actuated in response to a first predetermined number of
the Doppler pulses to the counting means, a bidirectional
clock pulses for coupling the Doppler pulses simultane
counter including a forward count input and a reverse
ously to the counting means and the forward count input
count input, .a pulse source, a second gate coupling the
of the bidirectional counter during an interval between
output of the pulse source to the counting means, a third
successive clock pulses, means actuated in response to
gate coupling the Doppler pulses to the forward count 60 a second predetermined number of clock pulses for cou
input of the bidirectional counter, means in series with
pling the Doppler pulses to the reverse count input of
the second gate for interrupting the flow of pulses from
the bidirectional counter during an interval between suc
the pulse source to the counting means, means for actuat
cessive clock pulses, means for coupling said first train
ing said pulse interrupting means in response to the zero
of pulses to the counting means, means for coupling the
count condition of the bidirectional counter, whereby the 65 second train of pulses to the reverse count input of the
flow of pulses to the counting means is interrupted when
bidirectional counter, and means coupled to the bidirec
the bidirectional counter is in the zero condition, a
tional counter for interrupting said first and second train
divider coupled to the pulse source through the second
of pulses in response to a zero condition of said bidirec
gate and the said pulse interrupting means, the output of
tional counter.
the divider being coupled to the reverse input of the bi
70
directional counter, the divider producing output pulses
fired projectile from Doppler frequency measurements
made at points along the projectile trajectory remote from
the point of firing, said computer comprising means for
75 converting the Doppler frequency measurements into
at a predetermined ratio in number of pulses to the input
pulses, a source of clock pulses, means actuated in re
spense to the clock` pulse source for opening the first
and third gates simultaneously a predetermined number
5. A computer for determining the initial velocity of a
3,034,049
9
Doppler pulses at a varying repetition frequency propor
tional to the projectile velocity, a local pulse source for
generating correcting pulses, pulse counting means, a first
gate for coupling the Doppler pulses to the pulse count
ing means, a second gate for coupling the correcting pulse
output of the local pulse source to the pulse counting
.
_
10
t
n
and said pulse interrupting means, the output of the
divider circuit being coupled to the reverse input of the
bidirectional counting means, the divider circuit produc
ing a predetermined ratio of output pulses to input pulses,
and timing means connected to the gates and switching
means, the timing means being triggered in response to
the initial Doppler pulses produced at the firing of the
projectile and, in sequence, opening the first and third
gates after a first predetermined time interval, closing
tively connecting the Doppler pulses and the correcting
pulses to the counting means, bidirectional pulse counting 10 the first and third gates andY triggering the íirst and second
means, first switching means interposed between the first
and second gates and the pulse counting means for selec
means having a forward count input and a reverse count
switching means after a second predetermined time inter
input, a third gate for coupling the Doppler pulses to the
bidirectional counting means, second switching means in
terposed between the third gate and the respective inputs
of the bidirectional counting means for selectively con
necting the Doppler pulses to the forward input and the
val,V opening theV third gate after a third predetermined
time interval, and closing'the third gate and opening the
second gate after a fourth predetermined Vtime interval. v
7. A computer for determining the value `at a íirst in
stant of time of a quantity that varies `substantially linear
ly with time fromV the values of said quantity as deter
mined at subsequent instants of time, Where the input in
formation fed to the computer is in digital form, said corn
second gate and coupled to the bidirectional counting
means, said last-named means being responsive to the 20 puter comprising a vlocal pulse source for generating cor
recting pulses, pulse counting means, a first gate for cou
zero condition of the bidirectional counting means to
pling the input information pulses to the pulse counting
interrupt the output of the local pulse source when the
means, a second gate for coupling thercorrecting pulse
bidirectoinal counter is in the zero condition, a divider
output of the local pulse source to the pulse counting
circuit coupled to the local pulse source by the second
means, íirst’switching means interposedbetween the first
gate and said pulse interrupting means, the output of the
and second gates and the pulse counting means for se
divider circuit being coupled to the reverse input of the
' lectively connecting the input information pulses and the
bidirectional counting means, the divider circuit produc
correcting pulses to the counting means, bidirectional
ing a predetermined ratio of output pulses to input pulses,
reverse input of the bidirectional counting means, means
in series with the output of the local pulse source and the
and timing means connected to the gates and switching , pulse counting means having `a Áforward count input and
means, the timing means being triggered in response to 30 a reverse count input, a'third gate for coupling the yinput
infomation pulses to the bidirectional counting means,
the initial Doppler pulses produced at the firing of the
second switching means interposed between the third gate
projectile and, in sequence, opening the iirst and third
and the respective inputs of the Ibidirectional counting
gates after a íirst predetermined time interval, closing
means for selectively connecting the input information
the first and third gates and triggering the first and second
pulses to the forward inputand the reverse input of the
switching means after a second predetermined time inter
bidirectional counting means, means in series with the out
val, opening the third gate after a third .predetermined
put'of the local pulse source and the second gate and
time interval, and closing the third gate and opening the
coupled to the bidirectional counting means, said» `last
second gate after a fourth predetermined time interval,
named means being responsive to the zero condition of
the ratio of the dividing circuit being equal to
40 the bidirectional counting means to interrupt the output
of the local pulse source when the bidirectional counter
is in the zero condition, a divider circuit coupled to the ,
Where t1, t2, t3 and t4 are respectively said iirst, second,
third and fourth timing intervals.
6. A computer for determining the initial velocity of a
fired projectile from Doppler frequency measurements
made at points along the projectile trajectory remote from
local pulse source bythe second gate and said pulse in
terrupting means, the output of the divider circuit being
coupled to the reverse input of the bidirectional counting
means, the divider circuit producing a predetermined ratio
of output pulses to input pulses, and timing means con
nected to the gates and switching means, the timing means
being triggered at the occurrence in time of the quantity
the point of firing, said computer comprising means for 50 to be measured and, in sequence, opening the first and » ,
third gates after ia first predetermined time interval, clos
converting the Doppler frequency measurements into
ing the first and third gates and triggering the first and
Doppler pulses at a varying repetition frequency propor
second switching means after va second predetermined
tional to the projectile velocity, a local pulse source for
time interval, opening the third gate after `a third prede
generating correcting pulses, pulse counting means, a ñrst
time interval, and closing the third gate and open
gate for coupling the Doppler pulses to the pulse count 55 termined
ingy the second gate after ya fourth predetermined time in
ing means, a second gate for coupling the correcting pulse
terval, the ratio of the dividing circuit being equal to
output of the local pulse source to the pulse counting
means, iirst switching means interposed between the iirst
and second gates and the pulse counting means for selec
tively connecting the Doppler pulses and the correcting 60
pulses to the counting means, bidirectional pulse counting
means having a forward count input and a reverse count
fari-'Län
where t1, t2, t3 and t4 are respectively-said first, second,
input, a third gate for coupling ‘the Doppler pulses to the
third and fourth timing intervals.
bidirectional counting means, second switching means in
terposed between the third gate and the respective inputs 65 `8. A computer for determining the initial velocity of
a fired projectile from Doppler frequency measurements
of the bidirectional counting means for selectively con
made at points along the projectile trajectory remote
necting the Doppler pulses to the forward input and the
from the point of tiring, said computer comprising means
reverse input of the bidirectional counting means, means
for converting the Doppler frequency measurements into
in series with the output of the local pulse source and the
second gate and coupled to the bidirectional counting 70 Doppler pulses at a varying repetition frequency propor
tional to the projectile velocity, means for generating a
means, said last-named means being responsive to the
iirst train of pulses and a second train of pulses, the num
zero condition of the bidirectional counting means to
ber of pulses in the two» pulse trains during a given in
interrupt the output of the local pulse source when the
terval being in a ñxed predetermined ratio, pulse count
bidirectoinal counter is in the zero condition, a divider
circuit coupled to the local pulse by the second gate 75 ing means, a first gate -for coupling the Doppler pulses to Y
3,034,049
ll
1,2
the pulse counting means, a second gate for coupling the
gates and triggering the first/and second switching means
after a second predetermined time interval, opening the
third gate after a third predetermined time interval, and
closing the third gate and opening the second gate after
first train of pulses from said generating means to the
pulse counting means, first switching means interposed be
tween the first and second gates and the pulse counting
means for selectively connecting the Doppler pulses and
a fourth predetermined time interval.
the first train of pulses to the counting means, bidirec
tional pulse counting means having a forward count input
variable at a first instant of time from the magnitude
10. A computer for determining the magnitude of a
of said variable at subsequent instants of time, where
said variable is a substantially linear function of time
ond switching?means interposed between the third gate 10 and the input information is fed to the computer in digital
>and the respective inputs of the bidirectional counting
form, said computer comprising means for generating a
means for selectively connecting the Doppler pulses to
first train of pulses and a second train of pulses, the num
the forward input and the reverse input of the ybidirection
ber of pulses in the two pulse trains during a given inter
al counting means, means responsive to the zero condi
val being in a fixed predetermined ratio, pulse counting
tion of the bidirectional counting means to interrupt the
means, a first gate for coupling the input information
first and second pulse trains from said generating means
pulses to the pulse counting means, a second gate for
coupling the first train of pulses from said generating
when the bidirectional counter is in the zero condition,
means for coupling the second pulse train output from
means to the pulse counting means, first switching means
said generating means to the reverse input of the bidi
interposed between the first and second gates and the
rectional counting means, and timing means connected to 20 pulse counting means for selectively connecting the in
the gates and switching means, the timing means being
put information pulses and the first train of pulses to
triggered in response to the initial Doppler pulses pro
the counting means, bidirectional pulse counting means
having a forward count input and a reverse count input,
duced at the firing of the projectile and, in sequence, open
ing the first and third gates yafter a predetermined time
a third gate for coupling the input information pulses
interval, closing the first and third gates `and triggering 25 to the bidirectional counting means, second switching
the first and second switching means after »a second pre
means interposed between the third gate and the respec
tive inputs of the bidirectional counting means for selec
determinedtime interval, opening the third gate after a
tively connecting the input information pulses to the for
third predetermined time interval, and closing the third
gate and opening the second gate after a fourth predeter
ward input and the reverse input of the bidirectional
mined time interval, the ratio of pulse in the first and 30 counting means to interrupt the first and second pulse
second pulse trains during a given time interval being
trains from said generating means when the bidirectional
counter is in the zero condition, means for coupling the
equal to
second pulse train output from said generating means
to the reverse input of the bidirectional counting means,
35 and timing means connected to the gates and switching
means, the timing means, in sequence, opening the first
and third gates after a predetermined time interval, clos
ing the first and third gates and triggering the first and
Where t1, t2, t3 and t4 are respectively said first, second,
second switching means after a second predetermined
third and fourth timing intervals.
9. A computer for determining the initial velocity of 40 time interval, opening the third gate after a third pre
determined time interval, and closing the third gate and
a fired projectile from Doppler frequency measurements
opening the second gate after a fourth predetermined
made at points along the projectile trajectory remote from
time interval.
the point of firing, said computer comprising means for
l1. In a Doppler chronograph for measuring the muz
converting the Doppler frequency measurements into
zle velocity of a fired projectile, transmitter-receiver
Doppler pulses at a varying repetition frequency propor
means for producing Doppler pulses at a varying repeti
tional to the projectile velocity, means for generating a
tion frequency proportional to the projectile velocity, a
first train of pulses and a second train of pulses, the
local pulse source for generating correcting pulses, pulse
number of pulses in the two pulse trains during a given
counting means, a first gate for coupling the Doppler
interval being in a fixed predetermined ratio, pulse count
ing means, a first gate `for coupling the Doppler pulses 50 pulse output of the transmitter-receiver means to the pulse
counting means, a second gate for coupling the correcting
to the pulse counting means, a second gate for coupling
pulse output of the local pulse source to the pulse count
the first train of pulsesfrom said generating means to
ing means, first switching means interposed between the
the pulse counting means, first switching means inter
first and second gates and the pulse counting means for
posed between the first and second gates and the pulse
counting means for selectively connecting the Doppler 55 selectively connecting the Doppler pulses and the correct
ing pulses to the counting means, bidirectional pulse
_pulses and the first train of pulses to the counting means,
counting means having a forward count input and a re
bidirectional pulse counting means having a forward
verse count input, a third gate Vfor coupling the Doppler
count input and a reverse count input, a third gate for
pulse output of the transmitter-receiver means to the bi
coupling the Doppler pulses to the bidirectional counting
means, second switching means interposed between the 60 directional counting means, second switching means inter
posed between the third gate and the respective inputs of
third gate and the respective inputs of the bidirectional
the bidirectional counting means for selectively connect
counting means for selectively connecting the Doppler
ing the Doppler pulses to the forward input and the re
pulses to the forward input and the reverse input of the
and a reverse count input, a third gate for coupling the
Doppler pulses to the bidirectional counting means, sec
verse input of the bidirectional counting means, means in
bidirectional counting means, means responsive to the
zero condition of the bidirectional counting means to 65 series with the output of the local pulse source and the
second gate and coupled to the bidirectional counting
interrupt the first and second pulse trains from said
means, said last-named means being responsive to the zero
generating means when the bidirectional counter is in the
condition of the bidirectional counting means to interrupt
zero condition, means for coupling the second pulse
the output of the local pulse source when the bidirectional
train output from said generating means to the reverse
counter is in the zero condition, a divider circuit coupled
input of the bidirectional counting means, and timing
to the local pulse source by the second gate and said pulse
means connected to the gates and switching means, the
interrupting means, the output `of the divider circuit being
coupled to the reverse input of the bidirectional counting
means, the divider circuit producing a predetermined ratio
and, in sequence, opening the first and third gates after
a predetermined time interval, closing the first and third 75 of output pulses to input pulses, and timing means con
timing means being triggered in response to the initial
Doppler pulses produced at the firing of the projectile
3,034,049
13
14
nected to the gates and switching means, the timing means
from said pulse train producing means to the reverse count
input of the bidirectional counter during a second time
being triggered in response to the initial Doppler pulses
produced at the firing of the projectile and, in sequence,
opening the ñrst and third gates after a first predetermined
time interval, closing the first and third gates and trig
interval, means for generating first and second pulse
trains, means for coupling the pulse trains frornsaid
generating means respectively to the pulse counting means
gering the first and second switching means after a second t
and the reverse input of bidirectional counter following
said second time interval, and means responsive to the
predetermined time interval, opening the third gate after
zero condition of the bidirectional counter for interrupt
a third predetermined time interval, and closing the third
ing the output from said generating means when the bi
gate and opening the second gate after a fourth predeter
mined time interval, the ratio of the dividing circuit being 10 directional counter is returned to the zero condition by'V
the pulses from said generating means.
equal to
14. A chronograph for determining muzzle velocity of
Y a projectile fired from a gun, comprising transmitter
receiver means for producing a Doppler signal having a
15 frequency proportional to the velocity of the projectile, `
where t1, t2, t3 and t4 are respectively said iirst„second,
means responsive to the Doppler signal for generating a
first quantity proportional to the frequency of the Doppler
third and fourth timing intervals.
signal after a first interval of time following the firing of » '
"
the gun, means responsive to the Doppler signal for
12. In a chronograph for measuring the muzzle velocity
of a fired projectile, means for producing a train of pulses 20 generating a second quantity proportional to the fre-V
having a repetition frequency continuously proportional to
the projectile velocity, pulse counting means, bidirectional
pulse counting means having a forward count input- and
quency of the Doppler signal after >a second interval of
time following the first interval of time, means forV de
riving a quantity equal to thediiîerence between said first
a reverse count input, means for coupling pulses from said
Iand second quantity, means for deriving a quantity equal
pulse train producing means to the pulse counting means 25. to said difference _quantity multiplied by the ratio of said
and the forward count input of the bidirectional counter ` first interval of time to said second interval of time, and
means for adding said last mentioned quantity to said
during a Iirst time interval, means for coupling pulses
first quantity.
from said pulse train producing means to the reverse count
l5. A chronograph for determining muzzle velocity of
input of the bidirectional counter during a second time
interval, a pulse generator and a pulse divider, means for 30 a projectile fired from a gun, comprising transmitter
receiver means for producing la Doppler signal having a
coupling output pulses from said generator to the pulse
counting means and through said divider to the reverse
frequency proportional to the velocity of the projectile,
input of bidirectional counter following said second time
means for producing a count proportional to the frequency
of said Doppler signal after a first interval of time follow
interval, and means responsive to the Zero condition of
the bidirectional counter for interrupting the output from "
the generator when the bidirectional counter is returned
ing the firing of the gun, means for producingja count
proportional -to the difference in frequency of said Doppler
to the zero condition by the pulses from said generator.
13. In a chronograph for measuring the muzzle velocity
' ysignal after said first interval and after a second interval of'
of a fired projectile, means for producing a train of pulses '
time following said first interval, and means for generating
a signal proportional to said difference count, the pro
having a repetition frequency continuously proportional l* portionality factor being equal to the ratio of the ûrst
to the projectile velocity, pulse counting means, bidirec
interval to the second interval of time, and means re
sponsive to said last-named signal for modifying the count
tional pulse counting means having a forward count input
and a reverse count input, means for coupling pulses from
at the end of said first interval by an amount determined
said pulse train producing means to the pulse counting
vby said signal.
means and the forward count of the bidirectional counter 45
during a first train interval, means for coupling pulses
`
No references cited.
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