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Патент USA US2411572

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N°V- 26, 1946-
w. D. HERSHBERGER
'
PULSE ECHO SYSTEM
Filed June 2_5, 1941'
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Patented Nov. 26, Í94É
2,411,572
PULSE sono SYSTEM
William n. Hershberger, Haaaonñela, N. J., as
signor to Radio Corp
poration of Delawar eoration of America, a cor
Application J une 25, 1941, Serial No. 399,607
8 Claims.
This invention relates to improvements in pulse
echo receiving devices and particularly to means
for controlling the receiver sensitivity and the
scanning movements of the cathode ray indicator
of such systems.
In pulse echo systems, a pulse of energy is
radiated toward a wave reilecting object. The
reñected pulses may be received and applied to a
cathode ray tube provided with scanning means.
In such systems, it is desirable to regulate the
receiver sensitivity so that the receiver will not
be blocked by the outgoing pulses or very strong
echo signals from nearby objects. Furthermore,
since the cathode ray trace may be calibrated to
indicate the distance of the reflecting object, it
is desirable to provide a long scale so that the
distances may be read easily and accurately.
One of the objects of the invention is to pro
vide improved means for varying the sensitivity
(Cl. Z50-_1)
2
by the anode voltage applied through the anode
resistor Rl. The charging may follow the curve
marked CCI of Fig. 2. When the pulse from wave
Shaper 3 is applied to make the point G positive,
the tube Gl becomes’conductive and very rapidly
discharges the capacitor Gl as shown by the steep
line 2|. This applies a negative voltage to the
screen grids of the receiver tubes il' and makes
the receiver sensitivity approach zero. As the
capacitor CI is charged, the receiver sensitivity
is increased because the screen grid potentials
are restored to their normal value. The restora
tion of receiver sensitivity may be made accord
ing to a desired predetermined rate. It should be
understood that other than screen grid tubes may
be used and the controlling voltages applied to
electrodes other than screen grids.
The received signals are ampliñed and are ap
plied to a radial deflecting electrode 23 of the
20 cathode ray tube 25. In order that a lo-ng scale
mined time function. Another object is to pro~
may be provided in a tu-be of limited size spiral
vide simplined means for forming a spiral trace
deiiecting voltages are generated and applied as
in the cathode ray indicator of a pulse echo sys
follows: The currents from the oscillator l are
tem. An additional object is to provide means
applied to a frequency multiplier 2l. The cur
for deriving synchronously, from the timing oscil
lator of a pulse echo system, voltages of the de 25 rents of multiplied frequency are converted into
a two phase current by a phase splitter 29, which
sired wave form for controlling the sensitivity oi
may consist oi a conventional reactive and re
the pulse receiver and for controlling the sweep
sistive network: The two phase current is applied
of the pulse echo indicator.
to the deiiecting elements 3l of the cathode ray
The invention will be described by referring to 30 tube
to produce a circular sweep.
the accompanying drawing in which Figure 1 is
The circular sweep is converted into a spiral by
a schematic circuit diagram of one embodiment
applying voltages of more or less sawtooth wave
of the invention; and Figure 2 is a graph showing
form, illustrated by the curve CC2 of Fig. 2. The
the wave forms of the voltages deriving in accord
sawtooth voltages are applied in synchronism
ance with the invention.
,
35 with the outgoing pulses by applying the positive
Referring to Fig. l, a timing oscillator l is con
pulse voltages at G, through delay network 33, to
nected through a wave Shaper 3, which may be a
a tube G2 biased to cut-ofi. The anode of tube
non-linearly responsive device, and a keyer 5 to a
G2 is connected to a capacitor C2 and a resistor
transmitter l. The output of the transmitter is
applied to an antenna 9, which is preferably made 40 R2, which is connected through a shaping in
ductor L to the plus B voltage. The anode poten
directive by a reñector li and a director i3 or
tials are applied through an isolating network RC
the equivalent. The antenna 9 may -be connected,
to the radial deflecting electrode 23 of the cathode
according to the copending application Serial No.
ray tube 25.
184,354, iiled January 11, 1938, by Wolff and
Hershberger, for “improvement in Signalling 45 As thus arranged for each outgoing pulse, a
sensitivity control voltage, a radial deñecting
system,” to a receiver l5 or a separate receiving
voltage and a circular sweep voltage of appro
antenna may be used.
priate frequency are derived. rlî'he sensitivity
The receiver I5 may be of the radio frequency
control voltage is applied to the pulse echo re
or superheterodyne type employing thermionic
amplifiers and detectors Il. In the present ar 50 ceiver to diminish its sensitivity during the radia
tion of the outgoing pulse and to restore gradually
rangement, screen grid tubes have been used be
the receiver sensitivity until full sensitivity is
cause their sensitivities are readily controlled by
reached for receiving pulse echoes from the more
applying voltages to the screens in the following
distant objects. The circular sweep and radial
manner: Pulse voltages at the point G are applied
to a vacuum tube Gl, which is biased to cut-off. 55 defiecting voltages are applied to deiiect the
cathode ray of the indicator along a spiral path.
The anode circuit of the tube includes a capacitor
The
spiral path is swept once for each outgoing
Cl and a resistor Rl. The anode is connected
of a pulse echo receiver according to a predeter
through a capacitor i9 to one or more of the
screen grids of the tubes l'l of the receiver. When
pulse and may be calibrated interms of distance.
The delay circuit 33 is provided so that the phase
the tube GI is blocked, the capacitor Cl is charged 60 of spiral sweep may be adjusted with respect to
the outgoing pulses and zero of the calibration..
2,411,572
3
I claim as my invention:
l. A pulse echo system including a transmitter,
a receiver, a cathode ray tube having deflecting
electrodes and a radial deiiecting electrode, means
for applying to saidtransmitter a current of pre
determined frequency to produce pulse signals,
means for multiplying the frequency of said cur
rent, means for applying said current of multi
plied frequency to said deflecting electrodes to
produce circular rotation of said ray, a pair of
electrical networks respectively having different
4
a pair of electrical networks respectively having
different charging voltage characteristics, means
including said keyer for discharging said electri
cal networks abruptly and in synchronism with
said pulse signals, means for applying the charg
' ing voltage from one of said networks to regulate
kthe sensitivity of said receiver in synchronism
with said pulse signals, and means for applying
the output echo signal voltages from said receiver
lo and the charging voltage of the other of said
networks to said radial deflecting electrode re
charging voltage characteristics, means for ap
plying said pulse producing current to discharge
said electrical networks, means for applying the
charging voltage of one of said networks to vary
the sensitivity of said receiver, and means for ap
plying the charging voltage of the other of said
networks and the echo signal output voltage of
said receiver to said radial deflecting electrode to
spectively to produce echo signal indications and
to convert said circular movement into a spiral
movement starting in synchronism with said
pulse signals.
5. A pulse echo system including a transmitter,
a receiver, a cathode ray tube .having deflecting
electrodes and a radial deflecting electrode, means
for applying to said transmitter a current of pre
determined frequency to produce pulse signals,
produce respectively spiral deflections of said ray 20 means for multiplying the frequency of said cur
and echo signal indications.
rent, means for applying said current of multi
2. A pulse echo system including a transmitter,
plied frequency to said deflecting electrodes to
a receiver, a cathode ray indicator including de
produce circular rotation of said ray, a pair of
ñecting electrodes and a radial deflecting elec
electrical networks respectively having different
trode, means for keying said transmitter with a 25
charging voltage characteristics, means for ap
current of predetermined frequency, means for
plying said pulse-producing current to discharge
multiplying said keying frequency current, means
said electrical networks in synchronism with said
for applying said current of multiplied frequency
pulse signal production, means for applying the
to said deflectingY electrodes to produce circular
charging voltage of one of said networks to vary
30
rotation of said ray, a pair of electrical networks
the sensitivity of said receiver in synchronism
having predetermined charging and discharging
with said pulse signals, and means for applying
voltage characteristics, means for applying said
the charging voltage of the other of said networks
keying current to discharge said electrical net
and the echo signal output voltage of said receiver
works, means for applying one of «said charging
to said radial deflecting electrode to produce re
35
voltages to regulate the sensitivity of said receiv
spectively spiral deflections of said ray and echo
er, and means for applying the other of said
signal indications.
charging voltages and the output of said receiver
6. A system according to claim 2 including a
to said radial deflecting electrode to produce re
delay circuit interposed between one of said elec
spectively spiral deflections of said ray and echo
40 trical networks and said keying means for syn
signal indications.
chronizing said spiral deflections with said trans
3. A pulse echo system including a transmitter,
mitter keying.
a receiver, a cathode ray tube having -ray de
’7. A system according to claim l including a
flecting electrodes and a radial deflecting elec
delay circuit interposed between one of said elec
trode, a source of alternating current, a keyer
connected to said source and to said transmitter
for producing pulse signals, means for multiply
ing the frequency of said alternating current,
means for deriving a two-phase current from said
frequency multiplied current, means for applying
said two-phase current to said deflecting elec
trodes to produce circular rotation of said ray, a
pair of electrical networks respectively having
different charging voltage characteristics, means
including said keyer for discharging abruptly said
electrical networks, means for applying the
charging voltage from one of said networks to
regulate the sensitivity of said receiver, and means
for applying the output echo signal voltages from
said receiver and the charging voltage of the
other of said networks to said radial deflecting
electrode respectively to produce echo signal in
dications and to convert said circular movement
into a spiral movement.
4. A pulse echo system including a transmit
ter, a receiver, a cathode ray tube having ray de
llecting electrodes and a radial deiiecting elec
trode, a source of alternating current, a keyer
connected to said source and to said transmitter
trical networks and said keying means for de
laying the start of said spiral deñections with
respect to said pulse production.
8. A pulse echo system including a transmitter,
a receiver, a cathode ray tube having ray deflect
ing electrodes and a radial deilecting electrode,
a source of alternating current, a keyer connected
to said source- and to said transmitter for pro
ducing pulse signals, means for multiplying the
frequency of said alternating current, means for
deriving a two-phase current from said frequency
multiplied current, means for applying said two
phase current to said deflecting electrodes to pro
duce circular rotation of said ray, means includ
ing a pair of thermionic tubes having input and
output circuits, said output circuits respectively
including electrical networks having different
charging voltage characteristics, means for ap
plying voltages derived from said keyer to the
input circuits of said tubes to discharge said elec
trical networks, means for applying the charging
voltage from one of said networks to regulate the
sensitivity of said receiver, and means for apply
ing the output echo signal voltages from said re
ceiver and the charging voltage of the other of
for producing pulse signals, means for multiply
said networks to said radial deflecting electrode
ing the frequency of said alternating current, 70 respectively to produce echo signal indications
means for deriving a two-phase current from said
and to convert said circular movement into a
frequency multiplied current, means for applying
spiral movement.
said two-phase current to said deflecting elec
WILLIAM D. HERSHBERGER.
trodes to produce circular rotation of said ray,
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