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Dec. 17, 1946.‘
R, c‘ SANDERS, JRW E1- ALv ’
2,412,632 I
Filed March 2, 1944
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Dec. 17, 1946.
Filed March '2, 1944
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Filed March 2, 1,944
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Dec- 17,‘ 1946'
Filed March 2, 1944
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Patented Dec. 17, 1946
’ 2,412,632
umrro stares PATENT orrice
Reyden C. Sanders, .ln, and William R. Mercer,
Hightstown, N. 3., assignors to Radio Corpora
tion of America, a corporation of Delaware
Application March 2, 1944, Serial No. 524,794
10 Claims. (Cl. 250—1)
This invention relates to bomb release appa
ratus, and more particularly to improvements in
systems of the type described in copending U. S.
where A is the altitude, 91:32.2 feet per second
and t is the time of fall.
application Serial No. 524,795 ?led by Royden C.
and entitled Radio bomb release system.
The principal object of this invention is to pro
32.2 4.01
The horizontal distance D from the target at
which the bomb» must be released is thus:
vide a method of and means for energizing a
bomb release mechanism in response to radio re
D = V‘/i
Sanders, Jr., on the same date as this application 5
flection distance and speed measuring means.
where V is the horizontal component of the speed
Another object of the invention is to provide
of the airplane with respect to the target. In
a method of and means for electrically computing
other words, for any speci?c altitude there is a
the measured distance from the target at which
particular relationship between V and D which
the missile is to be released in order to hit.
A further object is to provide an improved 15 must exist at the instant the ‘bomb is released.
By means of radio re?ection equipment, such
method of and means for measuring the speed of
as an altimeter of the F-M type, the altitude A
an aircraft relative to an object on the surface.
may be measured continuously. Similarly, the
These and other objects will become apparent
slant distance (1 (Figure 1) to the target may be
to those skilled in the art upon consideration of
measured. The slant velocity u can also be deter
the following description, with reference to the
mined continuously by this type of equipment, as
accompanying drawings, of which Figure 1 is a
described hereinafter. Since the equipment
schematic diagram illustrating a bomb release
measures the slant distance and the slant speed
problem, Figure 2 is a group of graphs illustrating
relative to the target rather than the horizontal
_ relationships between speed, distance, and alti 25 distance and horizontal speed, it is necessary to
tude in the solution of the problem of Figure 1,
determine the point of release in terms of these
Figure 3 illustrates the determination of the lin
The horizontal distance to the target is given by
ear approximation to one of the curves of Figure 2,
Figure 4 is a schematic block diagram of a system
D = Vt
for performing the required functions of speed
and distance measuring and computation of re
D=d cos 0
lease distance for a given altitude, Figure 5 is a
schematic block diagram of a modi?cation of
Figure 4, Figure 6 is a group of graphs illustrating
the variations in frequency of energy radiated 35
V_cos B
and received by the system of Figure 5, and
Substituting in Equation 1
Figure '1‘ is a group of graphs illustrating beat
frequencies produced in the operation of the sys
d cos 0=cos 0t
tem of Figure 5, Figure 8 is a schematic diagram 40
of a counter and combining circuit applicableto
the system of Figure 5, and Figure 9 is a graph
. tacos, i,
showing the variations in current during opera
tion at points in the circuit of Figure 5 and 8.
Referring to Figure 1, a bomb is to be released
from an airplane at the point B, ?ying at an al
titude A, at the proper point to strike a target
at the point C. Assuming free fall of the bomb,
> D=horizontal distance
V'=hor'izonta1 speed
t=time of fall
v=slant speed relative to target
d=slant distance to target
In order to get the result in terms of slant dis
tance and slant speed rather than angle
Figure 3. The constants in and do are diiferent
for each altitude.
Refer to Figure 4. A speed measuring device
I, capable of providing a D.-C. output voltage
proportional in magnitude to the slant speed 11,
is connected to a sensitivity control 3. The de
vice may be of the radio re?ection type, described
The sensitivity
in the output
may of
be the
10 device I, or any other means for varying the pro
portionality constant m between the D.-€. out
put'voltage and the speed c.
' A distance measuring device
aranged to
provide D.-C. output proportional in magnitude
15 to the slant distance d, has its output circuit
connected in series with that of the control 3 in
opposing polarity, so that equal changes in the
two outputs would produce no change in their
Substituting in Equation 5
sum. The device 5 may also be of the radio re
20 ?ection type, similar in construction and operation to an F-M altimeter.
A'D.-C. source ‘i is also connected in series with
the outputs of the devices 3 and 5, through a
voltage control 9. The algebraic sum of the three
“which, for the sake ‘of simplicity in explanation,
a quadratic equation, the solution of which is
output voltages is applied to a relay device H,
' is ‘assumed to operate upon the occurrence of
Zero voltage at its input'circuit, although in fact
‘ it may‘ be'desig'ned to operate at any predeter
mined voltage, providing-an additional voltage is
. ,=i/_A_
supplied to it so that operation will occur when
Since the equipment will require a certain
the algebraic sum of the outputs of the devices
?nite time T to operate and release the bomb ‘ _3, ‘5 and 8 is zero.
after the relationship of Equation '7 is estab
The controls 3 and 9 are adjustable in accord~
lished, the dropping distance (1' must be in 35 ance with the altitude at which a bombing run.
creased accordingly, by adding to the time of
isto be made to positions corresponding to the
fall t the delay time T:
‘constants m and do, respectively. An altimeter
53, which may be of the above~mentioned radio
re?ection type, is provided to enable the pilot
40 'to maintain the altitude to which the controls 3
and 9 set. The controls may be ganged to a single
In practice, the delay time T may be of the
order of 70.4 second. The value must be deter
mined -for the particular equipment used.
manually operable knob, or automatically oper
ated from the altimeter by means of a servo
* tem, not shown.
- - A series of curves of slant speed Vs. slant drop
The curves do not pass
In the operation of the system, the controls
3 and 9 are'set as described. above, and the air-v
craft is ?own toward the target. The total volt»
. through zerov because they are based" on slant
( age applied to the relay circuit I l is proportional
speedand slant distance. When the airplane is
to mo+do—d. As the target is approached, the
component corresponding to at will decrease with
decrease in the slant distance. The component
corresponding to me will ordinarily decrease also,
I ping distance, for different altitudes may be plot—
I ted from Equation 8. Figure 2 shows a typical
group of suchcurves.
‘directly above the target, the distance to the
target is the altitude, rather than zero.
In the system of the present invention, a
straight line approximation to the curves of Fig
ure 2 is used, rather than the actual non-linear
shows one of the curves of Figure 2, plotted (dash
although at a varying rate, because of decrease in
'the value of cosine 0 (see Figure l) as the target
is approached. When the condition ci‘ Equa
tion 9
line) on a different scale so as to accentuate the
relation between speed and distance.
Figure 3
non-linearity. To obtain the best approxima»
tion to the curve, arange of speeds most likely
to be used is selected. The lower and upper limits
of this range are designatedvv c1 and 212, respec
tively, in Figure 3. The corresponding dropping
distances, determined from Equation 8, are 021
and d2. The solid line, representing the linear
approximation, is drawn with a slope
is reached, the total voltage applied to the relay
circuit I I is zero, and the bomb is released. Pro
the azimuth (horizontal direction of
’ viding
?ight) is correct, the bomb will strike the target,
within the-limit of error of the linear approxi
~matio-n. The-magnitude of this rror is greatest
altitude of 300
65. at-the highest altitude.‘ At
feet the maximum error over the range of
'110 ft./sec. to 500 ft./sec. (slant speed) is plus
"or minus 12 feet.
‘ The functions of speed measuring and distance
and in a position such that. its1maXimum l'devia
tion A from the dash curve is a-minimum' over the 70 measuring may be combined in one system, using
selected speed range.
a frequency modulated signal. Referring to
The equation of the linear approximation is
‘ ure 5, a transmitter I5 is coupled to an antenna
I ‘I and arranged to be varied cyclically in fre
' d=mv+do
quency by means of. a frequency modulator I3,
where do is the distance intercept, indicated in 75 Which may be of the vibratory variable capacitor
requires a ?nite time to travel from the trans
mitter to the target and back to the receiver, the
type described in copending U. S. application
Serial No. 471,003, ?led January 1, 1943, by S. V.
received signal is delayed with respect to' the
Perry and entitled Capacity modulator unit. The
transmitted signal, and the variation in frequency
modulator I9 is connected to be energized by the
of the received signal will follow that of the
output of a wave shaping circuit 2|, which is
transmitted signal by an interval proportional to
connected through an adjustable voltage divider
the distance as shown by the graph 59 in Figure 6.
23 to a battery 25 and a periodically operable
Thus the transmitted and received signals will
switch 21. The circuit 2! is of the type described
constantly differ in instantaneous frequency by
in copending U. S. application Serial No. 512,153
?led November 29, 1943, by Irving Wol?‘ and en 10 an amount proportional to the distance, causing
the detector 29 to produce a beat output of the
titled Vibratory mechanical systems, and is de
difference frequency, as indicated by the graph
signed in accordance with the mechanical char
6| of Figure 7. The beat frequency is
acteristics of the modulator IE to provide substantially linear triangular wave variation of the
capacitance thereof in response to square-wave 15
input to the wave shaping circuit.
cycles per second, where S is the sweep width,
A detector 29, preferably of the balanced type
or range of variation of frequency of the trans
described in copending U. S. application Serial
signal in' megacycles per second per sweep,
No. 445,720 ?led June 4, 1942, by R. C. Sanders, Jr.,
and entitled Frequency modulated altimeter or 20 in; is the modulating frequency in cycles per
second, and d is the distance in feet.
distance indicator, although any suitable beat
If the equipment is on a vehicle which is mov
detector may be used, is connected to a receiving
ing toward the target, the received signal is
antenna 3| and to the transmitter IS. The out
shifted by Doppler effect to a higher frequency
put of the detector 29 is applied through an
by an amount proportional to the velocity, as
ampli?er 33 to a limiter 35. The output circuit
shown by the dash line 53 of Figure 6. The beat
of the limiter 35 is connected through a double
frequency is correspondingly decreased during
throw switch 31 to a pair of- frequency responsive
periods that the transmitted signal increases
devices 38 and 4|, which may be averaging cycle
in frequency, and increased during the periods
counters or other means for providing D.-C.
that the transmitted signal decreases in fre
output proportional in magnitude to the fre
quency, providing a beat frequency output from
quency of an A.-C. input. The switch 31 is
the detector z?wvhich varies as indicated by the
mechanically coupled to the switch 21, so that
graph 65 of Figure '7. The average beat fre
the limiter output is applied to the counter 39
quency is proportional to the distance, and the
‘while the switch 21 is closed, and to the counter , range
of variation of the beat frequency is pro
4| while the switch 21 is open. The switches 21 :
portional to the velocity. The change in fre
and 31 are connected to a motor 43 for periodic
quency caused by Doppler effect is
actuation thereby, as schematically indicated by
the dash line 45.
The counter 39 is connected so as to provide an
output voltage which is positive with respect to
ground and which increases with increase in input
cycles per second, where f0 is the carrier fre
quency, z; is the radial velocity in feet per second
frequency. The counter 4| is connected to pro
relative to the target, and C is the wave propaga
vide an output voltage which is negative with
tion velocity in feet per second.
respect to ground and which increases with in
The beat frequency output of the detector 29
crease in input frequency, but at a lower rate 45
is ampli?ed by the ampli?er 33 and limited to a
than that of the counter 39. The output circuits
constant amplitude by the limiter 35. The out
of the counters 39 and 4| are connected to a
put of the limiter 35 is applied through the switch
common load resistor 41 which is bypassed by a'
31 to the positive counter 39 during increase of
capacitor 49 and connected to a relay circuit 5|.
frequency of the transmitted signal, and to the
A D.-C. source 53 is also connected to the relay
negative counter 4| ‘during decrease of frequency
circuit 5|, through an adjustable voltage divider
of the transmitted signal. The output of the
55, so that the output of the voltage divider is
counter 39 corresponds in magnitude to the’
added to the voltage across the load resistor 41.
beat frequency during increase of transmitted
The operation of the system of Figure 5 is as
frequency, and is the difference between two com~
follows: The motor 43 operates the switch 21,
ponents proportional to distance and to speed
cyclically connecting the battery 25 across the
respectively. The output of the counter 4| corre
voltage divider 23 and thus providing a square
sponds in magnitude to the beat frequency during
wave input to the wave shaping circuit 2|. The
decrease of frequency of the transmitted signal
output of the circuit 2| actuates the frequency
modulator l9, varying the frequency of the trans— 60 and is the sum of two components proportional
to distance and to speed respectively. If the two
mitter l5 cyclically and linearly with respect to
counters were of equal sensitivity, the portions of
time, as illustrated by the graph 51 of Figure 6. '
their outputs corresponding to distance would
A small portion of the output of the transmitter
cancel in the resistor 41, and the voltage across
I5 is applied directly to the detector 29, and the
the resistor 41 would be proportional to speed.
remainder is radiated by the antenna l1. Some
However. as stated above, the sensitivity of the
of the radiated energy strikes the target (not
counter 39 is greater than that of the counter 4| .
shown) and is reflected to the receiving antenna
See Figure 9, wherein the average current Io
3|. The antennas l1 and 3| are preferably both '
through the resistor 41 is analyzed to show the
directive, to, avoid the effects of re?ection by
average component I1 of current during modula
objects other than the desired target.
tion upsweep due to distance only, the average
_ Assuming that the distance of the target from
component I2 of current during downsweep due
the antennas-l1 and 3| remains constant, the
to distance, only, the resultant average com
reflected signal picked up by the antenna 3| will
ponent I3 of current due to distance, the increase
vary in frequency over the same range as the
I4 in negative average component of current duré
transmitted signal. Since the radiated energy
ing downsweep due to speed, and thedecrease Is
in positive average component of current during
The operation of the system of ‘Figure 8 is as
follows: The motor I95 operates the switch I89
upsweep ‘due to speed. Accordingly, the total cur
rent through the resistor 41, and hence the
voltage across it, is proportional to
periodically to ground and unground alternately
the upper end of the voltage divider I87, causing
the voltage at this point to alternate between
ground potential and substantially B+ potential.
This square wave voltage is applied to the con
where m depends upon the ratio of the sensi
trol grid circuit of the tube I55 and through the
tivities of the counters 39 and M and upon the
relative responses of the system, in beat frequency 10 phase inverter £93 to the control grid circuit of
the tube I53, causing the tubes I53 andv I65 to
cycles per second, to distance and to speed.
The carrier frequency in, which determines the
speed sensitivity, and the modulation frequency
fm, which, together with the band width S, deter»
mines the distance sensitivity, are predetermined
in accordance with practical considerations not
directly related to the‘ values of m which will be
become conductive and non-conductive alter?
nately with respect to each other. A’ similar
square wave voltage of lower amplitude appears
at the tap I 9! and is applied to the frequency
modulatoncausing the frequency of the trans
mitter to increase while the switch I89 is open
and to decrease while the switch I39 is closed.
required. The counter sensitivities are then de
when the switch I89 is closed the tube I53
termined so as to provide the various desired
is conductive and acts as a diode, charging the
values of m by variation of the band width S over 20 capacitor H5 during the positive half cycles of
a predetermined range. Thus in the operation
the beat frequency input wave. The capacitor
of the system, the constant in is adjusted in ac»
cordance with altitude, by means of the voltage
divider 23. The voltage across the resistor It’! is
proportional to d-mv. The voltage divider 55
is adjusted, also in accordance with altitude, to
provide a voltage bearing the same proportion
ality to —do. The total voltage applied to the
relay circuit 5'I is proportional to d-1;w—da.
When this voltage becomes zero, the condition 30
of Equation 9, d=mv+do, is satis?ed, and the
i5I is discharged through the diode I 55 during
negative half cycles of the input voltage. These
operations tend to charge the capacitor I15 to a
voltage positive with respect to ground and pro
portional in magnitude to the frequency of the
input voltage. Whenthe switch I89 is open, the
tube m5 is conductive and functions as a diode.
During negative half cycles of the beat frequency
input, the capacitor 575 is charged through the
diode Mil and the capacitor I63. During posi
tive half cycles the capacitor I53 is discharged
through the tube I55. This operation tends to
charge the capacitor I '15 to a voltage negative
bomb release mechanism is actuated.
Figure 8 shows a preferred circuit for per
forming the functions of the switched counters
of Figure 5. The circuit of Figure 8 combines so in
with respect to ground and proportional in mag
the outputs of the preferred counter arrange
nitude to the frequency of the input voltage.
ments to determine the point of release as de
This action occurs only when the tube I85 is con
scribed above. The beat frequency input volt
age from the limiter, not shown, is applied
through a capacitor IE! to the anode of a triode
I53 and to the cathode of a diode I55. The
cathode of the tube H53 is connected to the con~
ductive since the capacitor £53 must be dis
charged after each beat frequency cycle in order
for the counter operation to take place.
Thus during the periods while the transmitter
frequency is increasing, the condenser I'I5 tends
trol grid of a pentode tube l5? which is provided
to becomefcharged positively and during the pe
with a load resistor I 59v in its cathode circuit.
The anode of the diode 455 is connected to a tap 45 riods when the transmitter frequency is decreas
ing, it tends to become charged negatively. The
IBI on the resistor I 59.v The input circuit is also
average voltage across the capacitor I75 is a
coupled through a capacitor I53 to the anode of
function of the difference between the beat fre
a triode I55 and to the cathode of the diode Gill.
quencies produced between the modulation up
The cathode of the tube IE5 is connected to the
and the modulation down-sweep, as de
cathode of the tube I5l, and the anode of the ,
scribed above in connection with Figure 1. The
diode I5’! is connected to the control grid of the
relative sensitivities of the counter circuits I53,
tube I57. The control grid of the tube I5? is
W5 and I55, £67 are determined by the capaci
tances of the condensers I5I and I63 respectively.
The voltage across the capacitor I15 is applied
A capacitor H5 is connected between the con 55 to the control grid of the tube I57. The tube I51
functions as a cathode-follower type ampli?er,
trol grid of the tube I51 and ground. The cath
automatically adjusting its anode current to a
ode of the tube 55'! is connected to the cathode
value such that the drop across the resistor E59 is
of an ampli?er tube Ill. A relay I79 is in
substantially equal to the voltage between the con
cluded in the anode circuit of the tube I'll. The
control grid of the tube IT‘! is connected through 60 trol grid and ground. The voltage across the re
sistor I59 is thus substantially the same as that
a resistor Hill vto an adjustable tap Hi3 on a volt
across the capacitor £115 but it is presented by a
age. divider. 185 which is connected between 3+
source of ‘much lower impedance and, therefore,
and‘ ground.
of better regulation characteristic. This voltage
An adjustable.voltagedivider i8? is connected
to the B+ terminal and through a switch I89 to 65 is applied to the cathode of the tube I65 to im
prove the linearity of counter operation by dis
ground. The adjustable tap ‘I9! is connected to
charging the capacitor IEB after each count to a
the frequency modulator circuit, not shown in
value closely approximating the voltage across the
Figure 8, and is mechanically ganged with the
movable contact E83. on the voltage divider I85. 70 capacitor H5. rather than to zero voltage. ‘The
anodeof the diode H55 is. returned toth'e resistor
The switch I89 is coupled to the control grid of
I58 for the same reason, but to the intermediate
the, triode I65, and through a phase inverter
point vit! which is slightly less positive than the
tube I93 to the control grid of the triode I53.
cathode of the tube I65. This is necessary to
The switch I89 is mechanically coupled to mo
prevent the diode I 55 from becoming continu
75 ously conductive and failing to operate properly.
returned through a resistor I69 to a tap Ill on a
voltage divider H3, which is connected between
the positive anode supply source B+ and ground.
The cathode voltage of the tube I5‘! is also ap
magnitude connected in series‘ with said load’
plied to the cathode of the tube I'll, As long as
the cathode of the tube Ill remains positive with
respect to the control grid, the tube I1‘! is cut off
and the relay I19 is de-energized and remains
open. When the voltage at the cathode of the
tube I79 becomes equal to or slightly negative
with respect to the grid voltage, the tube I'I‘i
3, A system for measuring the speed of a mobile
Icraft with respect to a re?ecting object, compris
ing means for radiating a frequency‘modulated
signal, means for receiving said signal after re~
?ection by said object, detector means for com
bining said radiated and said received signal to
‘produce a beat frequency signal, frequency re
conducts, operating the relay I19. A positive
voltage is applied to the lower end of the counter 10 sponsive counter means connected to said de
teeter means to produce a D.-C. voltage pro
load resistor I59 from the tap I'Ii 0f the voltage
divider I13 so that the charging of the capacitor
portional in magnitude to the frequency of said
I15 starts from a predetermined positive poten
beat frequency signal, second frequency respon
tential, rather than from zero. The potentials
sive counter means connected to said detector
of the cathodes of the tubes I5‘! and Ill vary 15 means to produce a 11-0. voltage proportional
similarly with respect to a similar positive refer
in magnitude to the frequency of said heat fre
ence potential. The taps I33 and Ni on the
quency signal but opposite in polarity to the out
voltage dividers I85 and I81, respectively, are
put of said ?rst mentioned counter means, a
adjusted to positions determined by the altitude
common load circuit connected to said ?rst and.
at which the equipment is to be used, and control 20 second counter means, means for preventing op-i
the quantities do and m respectively of Equation
eration of one of said counters during increase
9 set forth above. When the counter outputs
in frequency of said transmitted signal, and‘.
are such that the voltages at the cathode and
means for preventing operation of the other of‘
the control grid of the tube I‘?! are equal, the
said counters during decrease in frequency of,‘
conditions represented by Equation 9 for the 25 said transmitted signal.
particular altitude are ful?lled and the relay I19
4. An automatic bomb release system for air»
is operated. .
craft including means for producing an A.-C..
The invention has been described as a radio
signal which changes cyclically in frequency about;
speed measuring system in which a frequency ' a mean value Which corresponds to the distance
modulated wave is radiated, re?ected from the 30 of a craft from a target, and over a range of.‘
object with respect to which the speed is to be
frequency corresponding in width to the velocity.‘
determined. heterodyned with the transmitted
of said craft with respect to said target, a pair:
wave and the resulting beat frequencies combined
of frequency responsive counter means, means;
separately during the up-sweep and the down
for applying said signal to said counter means;
sweep of the frequency modulation cycle. 35 a relay circuit, means for applying the outputs;
Doppler effect causes a shift in the received sig
of said counter means in opposition to each other.‘
nal frequency during both the up-sweep and
to said relay circuit, means for preventing oper-n
down-sweep periods, alternately increasing and
ation of one of said counter means during pe-r
decreasing the beat frequency. The range of this
riods when the frequency of said signal is greater
variation is a, measure of the speed. By altering
than said mean value, and means for preventthe sensitivity of the system during the up-sweep
ing operation of the other of said counter means
period with respect to that of the down-sweep
during periods when the frequency of said signal
period, the system may be adapted to afford an
is less than said mean value.
indication of the occurrence of the predetermined
5. The invention set forth in claim 4 wherein
relationship between the distance to the re?ect 45 each of said counter means includes a pair of
ing object and the speed of approach. An em
electron discharge tubes, each including at least
bodiment of the invention has been described
an anode, and a cathode, an input capacitor con
wherein this eifect is utilized to control auto
nected to the anode of one of said tubes and to
matically the dropping 01” a bomb from an air
the cathode of the other of said tubes, discharge
50 circuits connected to the other anode and to the
We claim as our invention:
other cathode respectively, at least one of said
1. A radio bomb release system including
discharge tubes including a, control grid.
means for radiating a frequency modulated sig
6. The invention as set forth in claim 4, where
nal to a reflecting target, means for receiving
in said means for alternately preventing opera
said signal after re?ection and detector means 55 tion of said counter means includes a source of
for combining said received signal with said
substantially square wave voltage, means for ap
transmitted signal to produce a beat signal, fre
plying said voltage directly to one of said counter
quency responsive counter means for producing
means, and phase inverter means for applying
a direct current output proportional in mag
said voltage in opposite phase to the other of said
nitude to the frequency of an input thereto, sec 60 counter means.
7. The method of providing response to a pre
ond frequency responsive counter means for pro
ducing a second direct current output differently
proportional in magnitude to the frequency of
an input thereto, and of opposite polarity to the
current produced by said ?rst counter means, 65
means for applying said beat signal to said ?rst
counter means during increase of frequency of
said transmitted signal and to said second coun
ter means during decrease of frequency of said
transmitted signal, a common load resistor con
determined relationship between speed and dis
tance with respect to a re?ecting object, includ
ing the steps of transmitting a frequency mod
ulated signal to said re?ecting object, receiving
said signal after re?ection, combining said re
ceived signal with said transmitted signal to pro
duce a beat signal, deriving from said beat sig
nal during increase in frequency of said trans
mitted signal a D.-C. voltage proportional to
the frequency of said beat signal, deriving from
said beat signal during decrease of frequency of
nected to both of said counter means, and relay
means connected to said load resistor.
said transmitted signal a second D.-C. voltage
2. The invention as set forth in claim 1, in
proportional to the frequency of said beat signal
cluding a source of D.-C. voltage of adjustable 75 but of opposite polarity to said first D.-C. volt
2,412,632 7,
age, combining said ?rst and second ID.-C. volt
ages to provide a resultant D.'~C. voltage having '
an average magnitude proportional to the edge-‘
braic sum of said‘ ?rst and second-D.-C. volt
ages and effecting response to the attainment by.
said resultant voltage of a predetermined mag
A system for providing response to a pre
determined relationship between the speed andv
nal, and means for preventing operation of the
otherv of {said fcount‘e'rsi duringf'decreasein fre
quency ‘of 7said ‘transmitted? signal.
1 I
9.-Ai system“for-providing‘ response to a pre
determined relationship between speed anddis
‘tance, “includingir'adio ~' transmitter means, ireouencylmodulator means‘ ccnnected‘to said trans
mitter tor cyclically;varyingv the frequency of '
operation‘ thereon"; receiver ‘means including
the distance of a mobile craft ‘with respect to‘a 10 demodulator connected to said transmitter to pro- ‘
re?ecting object, including means forradiating
vvide a beat lfrequ'encyoutput in'response to re—'
a frequenc: modulated signal, means for receiv
?ection ofsignals ‘radiated by said transmitter,
ing said signal after re?ection by said object,
frequency responsive counter circuits ‘coupled to
detector means for combining said radiatediand
said demodulator "means :to provide 'D.-C. out
received signal to produce‘a beat frequency 15 puts having magnitudes of- different proportion
signal, frequency responsive, counter means con—
nected to said detector means to'produce a D.-C.
voltage proportional to the frequency of said beat
frequency signal, second frequency responsive
counter means di?ering in sensitivity from said _
?rst counter
‘and connected to said detece
tor means to produce a D.-C. voltage propor
tional to the frequency of said beat frequency
alities-to the'frequencyof ‘said beat frequency
voltage ‘and opposite-polarities, means for altere" ‘
nately rendering said counter circuits inoper
ative,- and means for ‘combining the outputs of '
said’ counter circuits to‘ provide a’ DQ-C.‘ voltage
:.:proportional in average 'magnitude ‘to the al'geé
braic sum of the outputs‘of said counter-circuits. ’
10; The invention ‘as set forth- in claim 8, in-'
signal but opposite in polarity to said?rst D.-C. .' cluding a relay device and-source of D‘.-C. volt- ‘
voltage, a common load circuit-connected to said 25 age of adjustable magnitude‘ connected in series
?rst and second counter means,’ means'for pre-‘
with'said common vload circuit.
venting operation of one of said counterstdur
ing increase in frequency of said transmitted ‘sigh,
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