close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2412670

код для вставки
1D@n 17, 1946.
D. w, EPSTEIN
-PULSE-ECHO POSITION INDICATOR
Filed June 26, 1942
2,412,670
Dec. 17, 1946.
D, W_ EPSTElN
2,412,670
PULSE-ECHO POS ITION INDICATOR
Filed June 26, 1942
„34
2 Sheets-Sheet 2
CHW/ODL' )MY
TUBE‘ 52
1G. Z.
4Z
NORTH
/NDlCH’í'l/VG
’
G. 36
Way/vc. PULSE
I-I
|
EG. 4. l
'I
l
Fiend;
, _pma
.
l
Ij 70 /vomw
fía. 6.
Fie., Z
FÍG.8a.
_ITM
""“91
'
L
_,igfJ/gggk ""ME _*
.sPo'r 35
SYNC.
Snnen‘tor
David WEpvsteLn
Gttomeg
Patented Dec. 17, 1946
UNITED STATES
PATENT ori-fica
2,412,670
PULSE-ECHO POSITION INDICATOR
David W. Epstein, Merchantville, N. J., assignor
to Radio Corporation of America, a corporation
i
of Delaware
Application June 26, 1942, Serial No. 448,663
-
1
8 Claims.
,
My invention relates to pulse-echo position indi
cating system and particularly to systems adapt
ed to convey the position information to a re
mote point or central station. It will be de
scribed as applied to‘a position indication sys
tem-in which a directive transmitting antenna _is
rotated horizontally to sweep a radio beam
>
through a horizontal plane while pulsing-the
beam. 'I'he radio pulse is reflected if it strikes
an- airplane or the like. The reflected pulse is
picked up by a receiver located near the pulse
transmitter and the distance of the reflecting
object is determined by the time elapsed between>
transmission of the initial or time-reference pulse
and receptionof the reñected pulse. The direc
tion of the reilecting object is determined also by
employing at the receiver a cathode ray indi
cator tube in which the cathode ray is deflected »
radially and at the same time, rotated in syn
(Cl. Z50-1)
.
2
.
‘
rate as compared with the rate at the indicator
tube located at the transmitter; these rates are
30 per second and 600 per second, respectively, in
the example describedl below. The signal for
5 pulsing or modulating the cathode ray of the
indicator tube at the remote station (this signal
corresponding to the reflected pulses applied to
the indicator tube at the receiver which is usu
ally located in the vicinity of the transmitter)
isobtained by applying the reflected pulses to a
second cathode ray tube at the transmitter to
store them on a fluorescent screen and by deflect
ing the cathode ray of this tube along a line trace
at the pulse rate. The resulting stored pulse ap
pearing at a point on the line trace is scanned by
a rotating disc having radial slits which scan the
line trace at the low frequency radial deflection
rate employed at the remotey indicator. When a
scanning disc aperture'comes opposite the light
chronism with the rotation of the transmitting- 20 spot on the line trace, a pulse of light is trans
mitted to a photoelectric cell to produce a cor
antenna.
responding electrical pulse. These pulses may
It may be desirable to install a plurality of sta
be transmitted .over an ordinary wire line such
tions of the above described type spaced apart
as a telephone line or over a narrow frequency
the proper distance to give protection over a
large geographical area. In that case it may be
band transmitter to the cathode ray tube indi
cator at the remote or central station since their
desirable to convey the information from all pulse
repetition rate in the example assumed is 30 per
echo stations to a central station where one per
second, instead of 600 per secondv as the trans
son has before him a view of all the position in
mitter station, with a corresponding reduction in
dicating views or patterns that are present at the
individual stations. A dimculty in doing this is 30 the frequency band. The invention will be better understood from
that such infomation ordinarily occupies a fairly
wide frequency band, from 100 to 60,000 cycles
the following description taken in connection with
the accompanying drawings' in which Fig. 1 is a
per second, for example. This band is too wide
diagram of a pulse-echo position `indicator sys
for transmission over the usual telephone, tele.
35 tem embodying the invention, Fig. 2 is a view of
graph or wire line.
the scanning disc shown in Fig. 1,- and Figs. 3 to
An object of the present invention is to pro
8a are graphs which are referred to in explain
vide an improved method of and means for re
ing the invention. Like parts in the figures are
- ducing the above-.mentioned frequency band, pref
erably enough to permit transmission of the po
indicated by similar reference numerals.
sition indication information over a wire line to 40 Referring to Fig. 1, a radio transmitter I0 is
keyed at the rate of 600 pulses per second. for ex
a central station.
,
ample, to radiate pulses of very short duration
Another object of the invention is to provide
from a suitable directive antenna Il. Antenna
an improved method of and means for conveying
Il may be a dipole in a parabolic reflector I2 or
>information from a radio pulse-echo position in
45 it may be of any other suitable design. It is ro
dicator to a remote point.
_
tated at 10 rotations per minute, forexample, in
A further object of the invention is to provide
a horizontal plane about a vertical shaft I3. The
an improved means for and method of producing
shaft I3 is driven by a synchronous motor It
an orienting indication in a system of the above
through a gear box I6, the mechanical coupling
- described type.
In one embodiment of my invention the posi 50 being indicated by the broken lines. The motor I4
is connected to a 60 cycle power line I6.' Suit
tion indication- at the remote station appears on
a cathode ray tube provided with a defiecting yoke
able pulse keying means I1 is driven by a syn
chronizing pulse generator I8.
that is rotated in synchronism with the rotation
of the transmitter antenna.` 'I'he radial deñec
The receiver I9, which is located in the vicin
tion produced by this yoke is at a low frequency 65 ity of the transmitter, receives 'the reñected pulses
` ‘
2,412,070
3
of carrier wave frequency, demodulates them, and
applies them to the control electrode .of a cath
ode ray indicator tube 2| having a fluorescent
screen 22; Tube 2| is provided with a rotat
rotated in synchronism with the antenna rota
tion. This may be done by a synchronous motor
51 that is driven synchronously from the tele
phone line as will be explained below. A sawtooth
deilecting wave recurring 30 times per second is
produced in the yoke 56 by a sawtooth wave gen
erator 3| to deiiect the cathode beam radially.
The generator 6I is held in ñxed time relation to
able deñecting yoke 23 of the magnetic type hav
ing slip rings 24 and 23 which are connected
through brushes to a sawtooth generator 21. The
yoke 23 is rotated synchronously with the an
tenne rotation by means of gears 23 and 23 which
the pulse transmission by synchronizing pulses
are mechanically coupled to the gear box I3.
transmitted over the wire line. It will be under
The sawtooth generator 21 is synchronized with
stood that atthe indicator tubes 2i and 54 the
the radio pulse transmission by means of pulses
sawtooth sweep is so phased with respect to the
from the synchronizing ~generator I3 supplied over
transmitter pulse that the deiiection starts from
a conductor 3l. The deiiecting wave applied to
the center of the fluorescent screen at the in
the yoke 23 contains a direct current component 15 stant the pulse is transmitted. The ñuorescent
such that the deñection of the cathoderay is
screen of the tube 54 is indicated at 53.
from the center of screen .22 toward the circum
The synchronizing pulses for controlling both
ference. The cathode ray tube 2| may be biased
the sawtooth generator 3i and the synchronous
nearly to beam current cutoii! in the absence of a
motor 5l are produced at a photoelectric cell 33
received pulse or to some value less than maxi
mum Ibeam current whereby a luminous spot ap
pears on the screen 22 upon the reception >of a
puise. This spot has a circumferential position
depending upon the direction of the reiiecting
object from the rotating transmitter antenna and
has a radial position (distance from center of
screen) depending upon the distance of the re
ñecting object from the transmitter antenna.
Ii an attempt were made to transmit the re
20
positioned opposite the scanning disc 42 whereby
light from a source I1 falls upon the cell 83 each
time a slit aperture 45 comes between the source
61 and the cell 66. A mask 65 may be provided to
deiine an area of light opposite a disc aperture. -
The resulting synchronizing pulses are amplified
by an ampliñer 68 and are supplied to the mix
ing ampliiler 50.
Reference or “north indicating" pulses 'il are
also produced by means of a photoelectric cell 33
ñected pulse, wnich recurs at 600 times per sec 30 and a light source 1 I positioned on opposite sides
ond, to a remote station over an ordinary wire
of the scanning disc 42. The pulses from the cell
line, for example, it would be found that the ñ
69 are ampliiied by an ampliñer 12 and are sup
delity of transmissionwould be very poor as the
line would not transmit the required frequency
band. Therefore, I have provided means for re
plied through a biased amplifier 13 to the mixing
ducing the frequency band required whereby in
ampliñer 50. A mask 14 limits the area of light
opposite the synchronizing slit.
Fig. 2_ indicates the relative radial positions of
fomation sent over a line to a central station will
give on the indicator tube an acceptable indica
tion of the position of the airplane or other re
the photoelectric cells 43, 53 and 36 (which have
been displaced toward the center of the scanning
disc to avoid confusion in the drawings) and of
fleeting object.
40 their associated light sources while Figs. 3 to 4
The frequency band reducing means comprises
show the photoelectric cell outputs and the way
a cathode ray tube 32 having a iluorescent screen
in which they are mixed. The rotation yof the
30 on the enlarged end. Deflection of the cathode
scanning disc 42 is in the direction indicatedr by
ray is provided by means of a pair of defiecting ,
the arrow. At the instant the disc 42 is in the po
coils 33 which are supplied with sawtooth current 45 sition illustrated, a synchronizing pulse (Fig. 3)
from the sawtooth generator 21. The 600 cycle
sawtooth current is synchronous with the keying
pulses.
`
‘
The tube 32 is properly biased nearly to beam
is being generated and a north indicating pulse
(Fig. 6) has just been generated. The line trace
34 and spot 35 (Fig. 4) have already been scanned
and will now be scanned again.
y
cutoff, for example, so that a spot of light 35 ap 50
A_S shown in Fig. 5, the synchronizing pulses are
pears on the screen 30 when a reilected pulse
reversed in polarity by ampliner 33 and are mixed
is applied to the control electrode of tube 32 over
in amplliler 50 with the signal representative of
a conductor 4 I. This light spot appears at a point
spot 35. Also, the reference or north indicating
on the linear deflection path or trace indicated by
the dotted line 34 and 'at a position determined
by the time that the reñected pulse appears upon
the control electrode.'-
.
'
pulse is combined with the signal (shown in Fig.
5) to produce the resultant signal shown in Fig. 7.
This signal is sent over the wire line to the central
station.
.
'
A rotatable disc 42 having a plurality of radial
At the central station the signalis ampliiled by
slit apertures 45 is located opposite the screen
ampliilers ‘I1 and 13 and is applied to the control
30. In order to direct light from the spot 35 to a 60 electrode of cathode ray tube 54 with the syn
photoelectric cell 43,v a lens system 41 is provided
chronizing pulses of negative polarity. The same
to image the light spot 35 on a disc aperture. The
signal, but preferably of opposite polarity, is sup
dise 42 is rotated te cause the apertures 4s to scan'
plied to a synchronizing pulse separator 18 where
the spot 35 at a low rate compared with the pulse
by synchronizing pulses may be supplied to the
’ rate, this being 30 per second in the example il
deilecting circuit 3| and to a tuned ampliiler 3l
-lustrated whereby theirequency band is reduced
which drlve's the motor 61. A diilïerential gear 32
yto 3%00 or 17g@ ot the original >band width. The
permits phasing of the yoke 53 by turning a crank
Vdisc may be driven by a motor 5I which may or
33.
‘
'
may not be synchronous. The pulse output of
The north indicating pulse appears on the
the photoelectric cell 43 is amplified by an ampli 70 screen of tube 54 only when the antenna il is
iler 52 and transmitted through a mixing ampli
pointing north (or is pointing in some other pre
fier 50 and over a wire line to the central station.
determined direction). This is accomplished by
At the central station there is a cathode ray
driving a switch 33 from the gear box I3 or from
indicator tube sa which, like the tube 2|. is pro
antenna shaft i3 so that the switch 33 is closed
vided with a rotatable deilecting yoke 53 that is 75 only when antenna il is pointing in the desired
$5,412,670
6
2. In a system for reducing the frequency band
required to transmit the information contained
direction. When the switch 88 closes it com
pletes a circuit through a conductor 81 to unblock
a relaxation oscillator much as a multivibrator
in a wave consisting of periodically recurring
I9 whereby multivibrator pulses 9| (Figs. B and
electrical pulses each of which occurs at a certain
time> after -the occurrence of a time-reference
pulse, means comprising a cathode _ray tube and
a screen associated therewith for storing an image
8a) are produced. When the switch 86 is closed
it connects the cathode of a- multivibrator tube to
ground to initiate a pulse 9|.
Multivibrator 89 is adjusted so that a pulse 9|
of said nrst pulses on said screen with said image
which is short enough to add only one "north in
spaced from a time reference point by an amount
dicating” pulse 'l0 is added thereto in the biased 10 determined by sai certain time, said means in
cluding deilecting m ansior producing a straight
amplifier 'I3 as shown in Fig. 8. As shown in
Fig. 8a, the antenna switch 86 is opened before
line trace'on. said screen, and means for scanning
another multivibrator pulse 9| indicated in dotted
said trace at a slower rate' than that 4oi’ the iirst
line in Fig. 8a can occur. As shown in Fig. 8, the ‘ ` pulses to convert said stored image to pulses re
ampliñer 'I3 is biased suñlciently beyond cutoiï 15 curring at said slowerrate, said scanning means
comprising a scanning disc having a plurality
so that a north indicating pulse is passed to the
mixing ampliñer 50 only upon the occurrence of a
of radial slits therein.
multivibrator pulse 8|.
3. In a radio system, means for transmitting
The persistence of fluorescence of the screen 83 I' pulses to an object whereby they are reflected
and of the screen 22 of tube 2i should be several
from said object, said pulses lrecurring at a cer
seconds, preferably six seconds where -the yoke
tain rate, means for receiving said reflected
rotates 10 R. P. M. (i. e., once in 6 seconds; The -
persistence of fluorescence of the screen 30 of the
pulses inthe region of the transmitting means,
there being a certain time interval between said
transmission and reception, a cathode ray tube
tube I2 should be at least l/too second (the time
of one deflection) and preferably is about 1/ao 25 having >a ñuorescent screen that has persistence
second in the example shown for good signal
of fluorescence, means for defiecting the cathode
' » to noise ratio. The fluorescence decays gradually,
ray along a linear trace on said screen at said
as is well known, but a satisfactory screen is one
certain rate, means for modulating said cathode
ray by said reñected pulses whereby an image
in which the light falls to one-half maximum in
` tensity in ‘lsu second, for example.
30 thereof is stored on said'screen, means for scan
From the foregoing it will be apparent that
ning said screen at a lower rate than said certain
the pulse produced in the photoelectric cell I3 oc
rate and for simultaneously taking signal oft' said
~‘curs at a time following the instant of pulse
screen at said lower rate to produce pulses at said
lower rate, said last means including a scanning
transmission which is measured by the time taken
for a disc aperture to rotate from a “zero delay" 35 disc having a plurality of circumferentially spaced
position which is at one end of the scanning
apertures located to rotate the apertures'past said
line 34 to the position of the spot of light 35. Thus
trace to scan it lengthwise, a cathode ray indi
the 30 cycle pulses sent over the line to the cen
cator tube having a beam control element, meansx
for applying said pulses occurring -at the lower
tral station have a time delay with respect to the
instant of pulse transmission that corresponds 40 rate to said control element, and means for de
accurately -to the delay between pulse transmis
fiecting the `cathode ray of said indicator tube
at said lower frequency.
sion and pulse reception at receiver i9. The
‘4.In a system for indicating the position oi’
radial position indication on the indicator tube
an object, means for transmitting pulses to said
M will be the same las on the indicator tube 2|.It will also be seen that the north indicating pulse 45 object from a directive rotating antenna whereby
is obtained, without the use of any mechanical
they are reflected from said object, said pulses
connection between the rotating antenna || and ' recurring at a certain rate, means for receiving
the scanning disc 42. This may be an important
said reflected pulses in the region of the trans
advantage as the frequencyreducing unit com
mitting means, there being a certain time inter
prising disc 42 may be located several hundred 50 val between said transmission and reception, a
feet from the antenna. A further advantage is
cathode ray tube having a storage screen, means
that with the proposed reference or north indi
for detlecting the cathode ray along a straight
cating system the scanning disc 42 itself need
line trace on said screen at said certain rate,
not be held in synchronism with the rotating an
means for modulating the said cathode ray by
tenna. A still further advantage is that .by means
said reflected pulses whereby an image thereof is
of my system a very exact timing of the north in
stored on said screen, means comprising a rotat
able disc having circumferentiaily spaced slits for~
dicating pulse is obtained at the indicator tube
scanning said trace at a lower rate than said cer
5I.
.
,
-
I claim as my invention:
,
tain rate andfor simultaneously taking signal'
l. In a system for reducing the frequency band 60 off said screen at said lower rate to produce pulses
occurring at said lower rate, a cathode ray indi~
required to transmit the infomation contained
in a wave consisting of periodically recurring
cator tube which contains means for generating
electrical pulses each of which occurs at a certain
an -electron beam, means for applying said lower
time after the occurrence of a time-reference
rate pulses to said- indicator tube to modulate said
pulse, means comprising a cathode ray tube and
beam, means for radially deiiecting the electron
a fluorescent screen associated therewith forbeam of said indicator tube, means for -rotating
l storing an image of said ñrst pulses on said nscreen
the plane of said radial deñection in synchronism "
with said image spaced from a time reference
with the rotation of said antenna, and means for
point by an amount determined by said certain
producing said radial deilection at said lower
~time, said means including deilecting means for 70
rate with the deflection from center starting sub
producing a straight line trace on said screen,
stantially at the instant of a pulse transmission.
and means for scanning said trace at a slower
5. In a system> for indicating the position of
rate than that of the i‘irst pulses to convert said
an object. means for transmitting pulsesto said
stored image .to pulses recurring at said slower
rate.
.
.
obiect from a directive rotating antenna whereby
/sntna-evo '
they are reflected from said object, said pulses
recurring at a certain rate, means for receiv
ing said reflected pulses in the region of the
transmitting means, there being a certain time
.
8
said renected pulses in the region of the trans
mitting means, there being a certain time inter
val between said transmission and reception, a l
cathode ray tube having a storage screen, means
interval between said transmission and reception, 5 for deilecting the cathode ray along a recurring
a cathode ray tube having a storage screen, means
for deflecting the cathode ray along a straight
path or trace on said screen at said certain rate.
means for modulating said cathode ray by said
reilected pulses whereby an image thereof is
line trace on said screen at said certain rate,
means for modulating said cathode ray by said
stored on said screen, means .comprising a ro
reflected pulses whereby an image thereof is 10 tatable scanning disc having a plurality of aper
stored on said screen, means comprising a rotat
tures for scanning said trace at a lower rate than
able disc having circumferentially spaced slits for
said certain rate and for simultaneously taking
signal oir said screen at said lower rate toipro
certain rate and for simultaneously taking signal
duce pulses occurring at said lower rate. .a cathode
o1! said screen at said lower rate to produce pulses
ray indicator tube which contains means for gen
occurring at said lower rate, a cathode ray in
erating an electron beam, means for applying
dicator tube which contains means for generating
said lower rate pulses to said indicator tube to
an electron beam, means for applying said lower
modulate said beam, means for radially deiiiecting>
rate pulses to said indicator tube to modulate said
the electron~ beam of said indicator tube, means
beam, means for radially deflecting the electron 20 for rotating-the plane of said radial deflection in
beam of said indicator tube, means for rotating
synchronism with the rotation vof said antenna,
the plane of said radial deflection in synchronism
means for producing said radial deñection at said
scanning said trace at a lower rate than said
with the rotation of said antenna, means for pro
ducing said radial/deflection at said lower rate
lower- rate with the deflection from center start- `
ing substantially at the instant of a pulse trans
with the deñection from center starting substan- 25 mission,r and means for increasing the intensity
tially at the instant of a pulse transmission, and
means for increasing the intensity of the indi
cator tube beam momentarily in response to the
of the indicator tube beam momentarily in re
sponse to the rotating antenna reaching a pre
determined point in its rotation, said last means
including a photoelectric device and light source
in its rotation.
30 for producing a reference voltage pulse in re
' 6. In a system for indicating the position of an
sponse to a scanning aperture moving across the
object, means for transmitting pulses to said ob
path of light from said light source to said pho
ject from a directive rotating antenna whereby
toelectric device, a biased amplifier tube, switch
they are reflected from said object, said pulses
means for producing a voltage pulse in response
recurring at a certain rate, means for receiving 35 to said antenna reaching said predetermined
»said reflected pulses in the region of the trans
point, and means for utilizing said last pulse to
mitting means, there being a certain time interval
unblock said biased amplifier momentarily to
.between said transmission and reception, a cath
pass one of said reference pulses to said indicator
ode ray tube having'a fluorescent screen that has
tube.
‘
'
persistence of fluorescence, means for deflecting 40
8. In a system for indicating the position oi'
the cathode ray along a straight line trace on
an object, means for transmitting vpulses to said
said screen at said certain rate, means for mod
object from a directive rotating antenna whereby
ulating said cathode ray by said reflected pulses
they are reflected from said object, said pulses
whereby an image thereof is stored on said screen,
recurring at a certain rate, means for receiving
means comprising a rotatable disc having cir
said reflected pulses in the region of the trans
rotating antenna reaching a predetermined point
cumferentially spaced slits for scanning said trace
l mitting means, there being a certain time inter
at a lower rate than said certain rate and for
val between said transmission and reception, a
simultaneously taking signal of! said screen at
cathode ray tube having a storage screen, means
said lower rate to produce pulses at said lower
for deilecting the cathode ray along a recurring ,
rate, a cathode ray indicator tube which con 50 path or trace on said screen at said certain rate,
tains means for generating an electron beam,
means for modulating said cathode ray by said
means for applying said lower rate pulses to said
reflected pulses whereby an image thereof is
indicator tube to modulate said beam, means for
stored on said screen, means comprising a ro
radially deiiecting the electron beam of said in
tatable scanning disc having a plurality of aper- ,
dicator tube, means for rotating the plane of 55 tures for scanning said trace at a lower rate than
said radial deflection in synchronism with the ro
said certain rate and for simultaneously taking
tation of said antenna, means for producing said
signal oii' said screen at said lower rate to pro
,radial deiiection at said lower rate with the de
f duce pulses occurring at said lower rate, a cath
- :Election from center starting substantially at the
ode ray indicator tube which contains means for
instant of a pulse transmission, means including 60 generating an electron beam, means for applying
a photoelectric device located adjacent to said
said lower rate pulses to said indicator tube to
scanning disc for producing synchronizing pulses
modulate said beam, means for radially deflecting
for synchronizing the deflection of said indicator
the electron beam of said indicator tube, means
tube, and means including a second photoelectric
for rotating the plane of said radial deflection in
device located adjacent to said scanning disc and 65 synchronism with the rotation of said antenna,
circumferentially displaced with respect to the
means for producing said radial deflection at said
other photoelectric device for increasing the in
lower rate with the deñection-from center start
tensity of the indicator tube beam momentarily
ing substantially at the instant of a pulse trans
in response to the rotating antenna reaching a
mission, and means for increasing the intensity
predetermined point in its rotation.
of the indicator tube beam momentarily in re
'7. In a system for indicating the position of an
sponse to the rotating antenna reaching a pre
object, means for transmitting pulses to said ob
determined point in its rotation, said last means
ject from a directive rotating antenna whereby
including photoelectric means for producing a
they are reñected from said object. said pulses
reference voltage pulse each time a scanning
recurring at a certain rate, means for receiving 75 aperture passes a certain point, a biased ampli
2,412,670 A
9
10
fier, a. relaxation oscillator which is normally
blocked and which ls adjusted to produce a volt
age pulse of a duration greater than that of said
reference pulse but less than the period of re
currence of said reference pulses when it is un
blocked, switch means for producing a Voltage
pulse in response to said antenna reaching said
last pulse to said relaxation oscillator to unblock
it momentarily, and means for applying said ref
erence pulses and said relaxation oscillator pulses
in additive relation to said biased ampliñer and
with such amplitudes that only the reference
predetermined point, means for applying said
pulse which is added to a relaxation oscillator
pulse is passed by said biased ampliñer.
DAVID W. EPSTEIN.
Документ
Категория
Без категории
Просмотров
0
Размер файла
807 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа