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Патент USA US2408703

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Patented Oct. 1, 1_946
2,408,702
lUNITED)ÍS'ÍFMES PATENT OFFICE
- Y »George‘lClifford' Sziklai, Princeton, N, J., assigner
to Radio Corporation ofA America,- a corporation
' -
ofY Delaware
l; Application May 20, 1944, Serial No. 536,457
10 Claims.
(Cl. Z50-27)
v
2
'
.
.
_
Another object of my invention 'is to provide
My ,present invention relates generally to de
deflection. electrodes in a beam tube which are
tectors of angle modulated carrier waves, and
additionally adapted to -function as anodesof
more particularly to novel 'circuits for detecting
diode rectifiers.
frequency modulated carrier waves.
is well known, in the absence of special pre 'Cil ‘ Another object of this invention is lto provide
a :beam tube detector for FM waves, wherein fre
cautions .the conventional frequency modulation
quency variable waves causeV relatively different
(FM) detector not only has an output dependent
emission variations from'a pair- of secondary
on frequency variation, but also on intensity vari
emission surfaces thereby to. provide a' resultant
ation of the signal. Even in the case of a bal
anced FM detector circuit, :which has zero out
useful’
Still output
anothervoltage.'
object Yof this
U ‘ invention
’
is to
' Íim `
put at carrier frequency, crossemoclulation effects
are obtained if the carrier. intensity changes dur- '
prove reception of angle modulated carrier waves
ing production of output energy in ‘response to
frequency deviation', i; e. simultaneously with
reception of frequency-modulated signals. `In the
past an amplitudeflimiter stagev has' been used
by producing variable secondary electron emission
from an output electrode in response to phase
departures of a pair of signal voltages from a
.normal phase relation, variations in amplitude
of the signal voltages being Vautomatically com
prior to the FM detector to vminimize such car
rier intensity changes.v Limiters are, in general,
pensated for by Ycontrolv of said Yvariable emis
clipper tubes which require a minimum signal '
s1on.'ìv
ping, va comparatively large p-ortion ofthe gain
is diverted intoV amplifying carrier harmonics e
during actual limiting, For v'this reason the=stabilityv of> the preamplifier is'diminished for the
30
provide a detector for FMfwaves which is sub
stantially non-responsive to carrier intensity vari
ation >withoutrthe use of aspecial `limiterstage
f'-
'
'
into` effect.
drawing:
`
‘
,
1
~
-
'
Y
~
‘
'
'_
Fig. 1 showsthe electrodes of a beam tube of the
type employed Vin my invention,
'
Fig.»2 shows FM detector circuits employing the»
of the type employing` opposed rectiñers, usually
one electron emitter .cannot be Aconnected to'
ticularly objectionable - in- battery-operated- re'
by reference >tothe following description, taken
In- the
=
increased ñlamentpower. This latter fact is par--4
The novel 'features which I believe to be char
acteristic of- my invention are set forth with par
ried
,-fdetectors `
ground,> and,¿ therefore,za tube with indirectly
heated cathode must'be used thereby 'requiring
"
in connectionwith theI drawing, in which I have
indicated `diagrammatically several circuit or
ganiza'tions' whereby my invention may be car
' Itis Aan important object of my‘invention 'to
‘ In the conventional andprior FM
'
ticularity inthe appended claims; the inven
tion" itself,`however, las to both its organization
and methodof operation will best be understood
appear .during the normal tuning-process. ' »
priorto thek FM detector. y,
‘-‘
prove vgenerally the eliiciency and stability of FM
receivers,and vto provide an amplitude limiter-Y
free FM receiver system which is economical to
manufacture and assemble.
the detector and of the receiver.` While a limiter
normally has a- high gain when it is not clip
'l weak signal; or no+signal',’stat_e,- and the receiver
generally requires a noisemuting _circuit to sup-"
press: reproduction of inter-'station'noises ywhich
.
' 'Still other objects of my invention are to'im
to operate, and thisA minimum signal (threshold>
improvement level) determinesthe sensitivity of
40
Fig. 2a shows diiîerent positions of the electronV
beam on the target,
._
_
Fig. `3 shows a modiñed tube and circult.
_
Referringnow >to the accompanying drawing,
v wherein- like~ reference numerals in the different
ceivers.` Another'importan-t, object of my >inven
tion, thereforeris to'improve the construction and 45. figures designate similar circuit, elements, there
is'shown in Fig. 1 a tube envelope I of any de-l
gain of FM detector tubes byemploying a beam>
sired conflguration.~ >The electron emitter of the
`type of ,tube` permitting the >use of a grounded
primary electron emitter.`
2
l
It is a further object >'of my presentinvention
tube is an indirectly heated cathode I' >which is
laterally arranged relative to the axis of the tube.
to provide `a beam tube employing a target ele
50 The emitter I’ may be of the filament type, if
ment having portions capable of emitting second
ary electrons, and means> for controlling the elec
of ' electrons S which passes through a narrow
tron >beam ofçthe-tube so as to minimize the`
effects of intensity variations of the received en-y
ergyfon theA ‘output current ofthe tube.
’
desired. The emitter l’ provides a beam or sheet
space or slit between the forward wings or flanges
1 andv 8,of respective deflection plates 2 and 3.
The plates' 2 and 3 are spaced in parallel rela-r
2,408,702
3
4
tion, and the flanges 'I and 8 are each bent nor
mally to the planes of the plates. As will be ex
one or more selective high frequency amplifiers
followed, if the receiving circuits are of the super
heterodyne type, by a converter which functions
to produce the intermediate frequency (I. F.)
signal energy.
plained in further detail at a later point, flanges
‘I and 8 function as respective spaced diode an
odes relative to common cathode I’. The beam
or sheet of electrons S passes ythrough spaced con
‘trol grids 4 and 5 and falls on target plate 6.
The latter, as shown, is provided with a central
triangular area 6’.
The target 6 is of conducting material, and one
portion of its inner face is a high secondary elec
tron emission surface, i. e. it emits a copious flow
of secondary electrons upon bombardment by the
beam of primary electrons S. However, the dark.
area 5’ of the target 6 has a relatively low sec- ’
ondary emission characteristic, so that upon
bombardment of area ß’ by the beam of electrons
S relatively less secondary electrons are emitted
therefrom. The area, 6' may be provided by a
coating of carbon for poor secondary electron
emission, while the high secondary electron emis
The I. F. signal energy may be of a mean fre
quency chosen from a range of 2 to l5 mc., for
example 4.3 mc. My invention is not limited to
thespeciñc I. F. band, as values' up to 100 mc. can
be used. The ampliñer V1 ampliiies the I. F. sig
nal energy at the selected 4.3 mc. value.
In the
plate circuit of amplifier V1 there is arranged a
resonant circuit Ci-Li tuned to the operating
LF.. value.A The low potential side of circuit
`‘C1-Li isv connected to the B-i- terminal of the
direct current energizing source through resistor
9, while condenser I Il bypasses all I. F. currents to
ground. Resonant circuit Lz-Cz is tuned to the
operating I. F. value. Coils L1 and L2 are mag
netically coupled, while direct current blocking
condenser: Ca'connects-'the- midpointof coil Lz to
sion may be provided by a caesium oxide coating.
Further, the target 5 could be madey of silver~
the high alternating - potential side of circuit
target the low emission area 6’. If desired, the
area 5’ of the target may be the smaller portion
of theïentirearea of target 5.
Seeley ink his U.> S. Patent No. 2,121,103, granted
June. .21, 1938. My invention is not restricted,
however, to this specific> form of discriminator, as
any other form ofsuitable frequency‘discrirnina
tor> circuit may be usedv priorto the tube I.
C1---~Li. The network Ci--Li and Cz-'Lz and its
associated elements-_provide a, form of frequency
magnesium alloys, or caesium on silver. InA either
of the latter cases‘there would be formed on the 25 discriminator disclosed and .claimed by S, W.
When theV beam S is deflected in such. a way
that the major portion ofthe electrons thereof
land on the high secondary emission surface of
target 6,.a large number of negative secondary
The output’terminalsïof circuit Cz-Lz are con
nected to-the controlelectrodes of tube I. Elec~
tron emitter I’ of tube Iv (the latter'is schemati
electrons leave the latter. Hence, the target as
»cally represented in Fig. 2) is connected to
sumes a relatively positive potential. On the
ground, and also tothe junction of resistors Ri
other hand, when the beam is deflected so that
and R2. The latter two elements are connected
the major portion of the electrons hits the low
in series across' the tuned circuit C2-L2. The di
emission surface 5', less electrons leave the target
rectv current blocking condenser I'I connects one
6 vthan are collected. Hence, the target becomes
side of secondary circuit Cz-Lz `to the upper end
relatively negative in potential. The tube shown
in Fig. l, therefore, provides a device for varying 40 of resistor Ri, whereas the blocking'condenser I2
connects the opposite side‘of circuit Cz-Lz to the
theeffe'ctive potential of an electrode by sweep
lower end'of resistor'Rz.
ing a beam of electrons across secondary emission
Deflection plate 2 is connected to resistor Ri,
surfaces of different emîssivity in accordance
with the relative potentials of a pair of beam
and deflection plate 3` is vconnected to resistor R2.
It will'be seen that each of diodes I’--ï and
control electrodes.
I'--8.is> connected in shunt; with a respective one
In> Fig. 2 I have shownl tube I connected in an
of resistors R1 and R2, the junction of the latter
FM receiver to function as an FM detector. The
being at ground potential. The grid 5 is estab
FM receiver is assumed to be a superheterodyne
receiver employed in the 42-50 megacycle (mc.)
lishedat a suitable positive potential B-|-+, the
voltage supply lead 'being properly bypassed to
band, the presently-assigned FM broadcast band.
ground for I. F. currents by condenser I`3. The
In that band each carrier frequency is deviated
in accordance with modulation signals. The ex
grid 5 acts, therefore, as a positive screen grid.
tent of frequency deviation is a function of mod
Grid 4 is‘connected by lead I'II to condenser C3
ulation signal amplitude, while the rate of devia
so that >the I. F. voltage across primary circuit
tion is dependent upon the modulation frequen 55 Cr-Li is applied `to grid-f4. A resistor R3 is con
cies per se. The permissible frequency deviation
nected from grid 4 to ground thereby to develop
or swing, in accordance with present broadcast
across the resistor, in a manner ‘further described
transmitting standards, is a maximum of 75 kilo
hereinafter, a recti'f-'led‘voltage which, after filter
cycles (kc.) to each side of the carrier frequency.
ing at IA" inthe usual manner, is used for A. V. C.
The invention is not restricted to the FM fre 60 bias. The IA. V. C. (automatic volume control)
quency range of 42-50 mc., nor to FM wave re
bias may be applied by lead I 5 to the signal con
ception, nor- to the specific over-al1 deviation
trol grids of >prior signal transmission tubes for
range of 150 kc. The term “angle modulated car
the customary A. V. C. action.
rier wave” used in this specification includesv
The target or secondary emitter 6 may be con
phase modulated (PM) carrier waves or FM car
nected directly to ground. However, it is pre
rier waves, or hybrid modulations of PM and FM
ferred rather to connect targetfß to a potential
possessing characteristics of each.
point which is positive relative to ground, but
The tube V1 is an amplifier preceding the usual
which is kept substantially less positive than the
discriminator network feeding the tube I. Am
potential of screen 5,. In Figs. 2 and 3 the lower
plifier V1 may be anon-limiting intermediate fre 70 positive potential of velectrode 5 is denoted by
quency (I. F.) amplifier whose input electrodes
one'plus sign, in place of the two plus signs of
are coupled to a prior I. F. amplifier, or to a con
screen 5. This positive potential of target 5 will
verter. The networks which precede I. F. am
ermit the landing of an increased number of
plifier tube V1 are of suitable and usual construc
primary electrons.- and thereby augments the
tion. They may comprise a signal collector and 75 emission of ' secondary electrons. VWhile it is
2,408,702
trueA that `the target 6 Vvvouldvassume apositive
lpotential due tothe net loss of electrons: anyway,
target voltages of higher gaingcan. 'be obtained
if the target is `startedat a positive potential.
The screen- 5, of course, functions. as an electron
collector, since it collects all secondaryelectrons
"titled .voltages derived: from " the ¿respective `1re
sultant voltages. 'Thesefrectiiied voltages will be
¿equal at resonance, :and ëbe' unequal `in Vresponse
toinequalitylof the resultant vector voltages at
the ends.:of..Lz-‘Cz. The effect. of the rectiñed
'voltagesracross R1 ¿and :Ra impressedon deflec
emitted by the target» 6. The target- 6 is con
nected to its B+ terminal iby resistor -I-6 `bypassed
tionr'platesfZ and 3 respectively, on the sheet of
‘electrons’S .will beto-deviate :the latter relative
to ground by condenser- l6’ for I. :F."cu-rrents. ~
tov itsnormal median position andr inv accordance
The voltage developed across resistor 1611s mod l10 Withf-frequency'modulation of the received sig
ulation signal voltage. y AIt corresponds to, land
is representative of, the modulation vsignals-em»
ployed »to modulate the carrier at .the FM tra-ns
mitter. The modulation-.amplifier
has 'its in.
put grid electrode »coupled to the resistor lß-by
blocking condenser 16ste amplify Vthe modulation
signal voltage across the latter. The resistor l'iii
is a high impedance elementand provides high »
gain forI ampliñer V2. The ampliñedmodulation
signal voltage isV developed across the resistor l1
arranged in the plate circuit vof tube V2; `By
passed cathode bias resistor I9’ provides normal
negative bias of amplifier V2. The amplified volt
age, when of yaudio frequency, Vvvill be furtheram
pliñed and finally reproduced in anyr desired .man 25
ner.
~
There will now be explained the manner in
nal.
~
Fis. 2a shows -the manner in which the Ytarget
is'swept ‘by the beam or -sheetxof electrons S.
When the: denection plate. 2' is more negative than
the Y. denection " plate 35 .the ^ >electrims ~ will . be f de
nec'tecitowards .thepplate 3. ~ The'dottedline aol"
Fig. 12u:` shows'the vertical line ofebombardment
of targeti.'6"at .the .instant ‘Whendeflection plate
2 is ,most .negative Yrelative to deflection yplate 3.
Sinoeffew secondary electrons are emitted from
thev high'emission surface of the output elec
trode' or target 6 because' such ‘surface- is not im
pactedhy `the electronv rbeam, and <the area, 6’
struck 4bythe electron beam'iszof-low secondary
electron emissìvity, so that> negative >electrons
collectv 'on'. the target7 the target 6 is Yat its least
positive potential.
.
which the present circuit'functions to> derive `the
Whenthe plates 2 Íand 3Á >are instantaneously
modulation‘voltage from the FM waves. v"lîhe I.
of' the same negativepotential, as vvhen'the.v cen.
F. or other high’ frequency signal energy atv pri 30 ter frequency `'ofi applied signal energy vis euual
mary circuit C1-L1 isinduced in- the secondary
tothe. resonant frequency ofthe discriminator
circuit Cz--Lz by the magnetic coupling there
circuit,l they sheetV ofàeiectronsr Sl will be in.. the
between. -The induced voltage'undergoes a phase
medianposition.I `The> dotted linev bl in Eig. 2u
shift of substantially 90° when the I. F. energy
represents vthe line V4of . bombardment ofl target » 6
mean frequency is equal to the predetermined 85 inv lsuch case. In this caserthe: electron beam may
resonant frequency of the coupled tuned circuits.
be dividedsubstantially equally between. the high
The phase-shifted voltage isy applied vto plates 2
secondary emission .arearand' 'the low emission
and 3 in push-pull relation dueto the midtap on
area: 6" of.' the target V6, and. the output electrode
coil L2. The primary voltage is’also- applied to
'6l-assumes fa median potential which is positive
the midpoint of coil L2 through condenser Ca
relativef‘to'lts'fbiasingîpotential B-|-.> The poten
This voltagev is applied inv parallel relation to
tial "of-output. electrode 6 under this ‘condition is
plates 2 and 3, and suffers no phase Yshift :since
more-positive'than in the case Whenthe elec
blocking condenser Gais too largeiiicapacity value
trons »fall ¿at line' a..> If the. deñection plate 3
to cause a phase shift inthe voltage- applied
should'lassumewits most .negative potential, for
therethrough.
.
l
whichV the circuits ïare designed relative' to plate
Hence, at each .of deflection plates 2' and 3_
2, thenithe dotted' line c in Figa@ Would repre
there exists Ya resultant voltage which, is produced
sent- the deflection- ofï electrons towards plate 2'.
by the vectorial combination of one of. the par
Here the electronibeam impacts.' substantially en
allel voltages and one of ithe phase-shiftedvolt
tirely on the high; secondary electron emission
ages. The resultant voltages atA the deflection 50 area of the target electrode 6.. and :the maximum
plates are in phase quadrature and. of equal meur-numberiof negative recording electrons; leaves the
nitude for the condition- ofr resonance Vbetween
target. - iHencathe electrodeÍ ~61~ attains its most
the mean. frequency ofthe LF. energy.v and .the
posi-tivefpotential which most’» closely approaches
predetermined resonant .frequency ofthe discrim#
the potential ofïscreen ‘grid VV5. It will according
inator circuit. Should the meanxfreduency of 55 ly.' bek understood that v.the- 'potential 'of output
applied I. F.. energyr instantaneously >depart from ’ electrode 6' varies. from armure positive to aßless
the resonance condition, the »phase relations will
positive value as theelectron beam seweepsfrom
depart from the quadrature relation, andv the re.- ' l linee to‘l'iïne a, »and from' a less positive to a
sultant voltages` -Will Abe unequal. . It will, there
more positive value as 'the electron beam moves
fore,.be seen that the resultant voltages on diode 60 in Ytheropposite 'direct-ion. - This develops a cor
anodes T and 8 and the respective deflection'.«platesl
respondingY potential' across high impedance I6,
2 and 3 varyy in relative magnitude in» response
which is ampliiied >with high gain'Y at mod
to the frequency deviationsçof the appliedl.. F.
ulation „amplifier V2. 'The secondary emission
energy.
The beam or sheet of electrons S. whose plane 65: is collected. by >screen 5. When this emission
is large the target 6 appears to' be connected
i‘s normal to the plane of target 6r is shifted or
toscreen 5 through `the resistance of the sec
deviated in response to the variations of the. niag~~
ondaryemission. .In other Words, the second
nitudesv of the resultant: voltagesprovidedat the
ary- electron> stream .from target. 6 to collec
deflection platesA 2 and 3. It will be recalled that
tube V1 is a non-limiting ampliñerpan'd applies
tor 5 -iunctionstsomewhat in the manner of va
connector of »variable resistance. . The. magnitude
both frequency and amplitude variations of the
of the effective resistance depends on» the» posi
carrier’to the circuit Cl-Lr. 'The resultant volt-`
ages at each'end of La-Cz- are reetiiied byr re
tion of'beam S-onthe target >6'. When the omis
spective- diodes lll-‘l and 1"-8. I Thus.. 4thereîis
developed; across each of. resistors'. "RL -and Rz. rece
sion from`~-,target>6 -to'screenwâ is high,- then tar
get .i isfeiîectively closer' to B++ in potential.
`2,408,702
7
When beam 5 is at line b of Fig. 2a, the applied
FM waves are at mean frequency.
A
As heretofore indicated, the constants of the
tube l and its circuits are preferably so adjusted
that the sheet of electrons S is swept between
lines c and a of Fig. 2 as limits.
The purpose of
this is to keep the beam from sweeping to the
right of line a, and rendering the electrode B
highly positive thereby producing a false impres
voltages from affecting the deñection plates.
Since each of plates 2’ and 3’ are connected to
the respective anode ends of resistors R1 and R2,
they will function in the same manner as eX
plained in connection with' Fig. 2. The control
grid 4, being adjacent the electron emission sur
face of cathode l', will exercise a rigid control
over the primary electron emission. As in the
case of Fig. 1, the primary circuit (C1-L1) Volt
Of course,
age is applied to grid 4, and the rectified voltage
cutting the target at line a will, also, prevent
over-swinging of the beam. In order to elim
inate the effect of any change in the amplitude
of the carrier, the primary voltage at C1-L1 is
intensity of the beam of electrons sweeping the
target 6. The rectified voltage across resistor
R3, after proper filtering, may be used for A. V. C.
sion that the beam is really at line c;
applied through condenser C3 without phase "
shift. The electrode 4 acts in th'e manner of an
across adjustable resistor Rs is used to vary the
bias. The embodiment of Fig. 3 functions other
wise in the manner described in connection with
the preferred circuit of Fig. 2.
The area E’ of target 6 need not be restricted
to a triangular configuration. If the beam of
anode of a diode rectifier consisting of electrodes
l’ and 4. Resistor Rs is the load resistor, and
direct current voltages thereacross are propor
tional to carrier amplitude variations. The di 20 electrons is sufficiently thick, the target could
have one path of its active face provided with a
rect current voltage across resistor Rs will bias
carbon coating and the other half could be a
control grid 4 negatively with respect to ground.
caesium surface. In this way according to the
This negative bias will affect the intensity of the
area of the beam landing on either surface, the
beam current and the consequent secondary elec
potential of target 6 would vary. It is preferred
tron emission from target 6.
to employ a triangular low emission area 6', since
Accordingly, the potential variation of target 6
it is a simple configuration and is particularly
will be reduced when the carrier amplitude is in
suitable for the practice of my invention.
creased, and the reverse will be true when the
While I have indicated and described several
carrier amplitude is decreased. This will pre
vent any increase in the slope of the typical dis 30 systems for carrying my invention into effect, it
will be apparent to one skilled in the art that
criminator characteristic if carrier amplitude in
my invention is by no means limited to the par
creases. By the proper adjustment of the mag
ticular organizations shown and described, but
nitude of resistor R3 the gain control by virtue of
that many modifications may be made vwithout
the action of grid 4 or the intensity of the elec
departing from the scope of my invention.
tron beam can fully compensate for the varying
What I claim is:
deiiection due to carrier amplitude changes, si
l. In combination with a beam tube of the type
multaneously with the reception- of frequency
having an output electrode provided with a sec
modulated signals. In other words, the variable
ondary emission area of predetermined non-uni
bias grid 4 functions to minimize the effect of
carrier amplitude variation on the electron stream 40 form configuration, means, adapted to be respon
sive to phase displacements of a pair of alternat
S which flows to the target 6. Amplitude var
ing current voltages from a predetermined nor
iations which occur at times of no signal recep
mal phase relation, for sweeping the electron
tion balance out by having equal effects on the
beam of said tube over said area thereby to vary
potentials of the deflection plates. For these
the potential of said output electrode and means
reasons the amplifier V1 may be a non-limiter '
responsive to amplitude variations of said volt
device. Furthermore, as heretofore stated,'the
ages for automatically controlling the intensity
voltage across resistor R3 may be used for bias
of said beam.
ing previous signal transmission tubes thereby
functioning as a usual A. V. C. circuit.
In Fig. 3 I have shown a modified form of cir- I
cuit, wherein the deflecting plates of tube l do
not function as diode anodes. In this modifica-~
tion special electrodes ‘l’ and 3’ are employed on
either side of the cathode i', the electrodes 1’
and 8’ functioning as the anodes of diodes l’--'I'
and |’-8’. The deflection plates are divergent,
and are indicated by numerals 2’ and 3'. The
resistors R1 and R2 in this case are connected as
before between the anodes and the common
cathodes of the respective diodes. The compen
sating grid 4 is located in this modification closely
adjacent to emitter i’ in order to provide better
control action. Furthermore, a beam-forming
electrode 9 is utilized between grid 4 and th'e in
put end of the deflection plates to provide a well 65
deflned beam on the target 6.
ì
In the modified embodiment of Fig. 3 the re
sultant' vector voltages at the opposite sides of
2. In an angle modulated carrier wave re
ceiver, a demodulator of the beam tube type pro
vided with an output electrode having at least
two secondary electron emission areas of differ
ent predetermined non-uniform configurations
and of different emissivities, one of said areas
completely surrounding the other area means for
translating received waves into a pair of modu
lated wave voltages of equal magnitude for the
condition where the mean frequency of the re
ceived waves is equal to that of a predetermined
reference frequency, means responsive to instan
taneous inequalities of said pair of voltages for
varíably deflecting the electron beam of the de
modulator tube in such a manner as to variably
sweep the beam across said two areas, and means
for deriving from said output electrode a voltage
representative of the modulation of the received
waves.
3. In an angle modulated carrier wave re
ceiver, a demodulator of the beam tube type pro
secondary circuit Cz-Lz are applied to diodes
I'--l' and I’--8’ for rectification. '_I‘he load re 70 vided with an output electrode having at least two
secondary electron emission areas of different
sistors R1 and R2, respectively in circuit with the
non-uniform configurations and of different
last mentioned diodes, develop across each of
emissivities, means for translating received waves
them the required direct current voltages for var
into a pair of modulated wave voltages of equal
iable biasing of deiiection plates 2' and 3'. The
magnitude for the condition where the mean fre
filters 20-2l and ZIV-2|’ prevent any I. F.
'giostra
9
‘
a predetermined reference frequency, means re- Y
sponsive to instantaneous inequalities of said pair
of voltages for variably deflecting the electron
beam of the'demodulator tube in such a manner
as to variably sweep the beam across said two
areas, means for deriving from said output elec
trode a voltage representative of the modulation
of the received waves, and means, responsive to
carrier amplitude variation, .for controlling the
intensity of said beam in a sense to render said
output electrode voltage independent of said `car
rier amplitude variation.
4. In combination with a beam Itube of the
type havingy an output electrode` provided with a
secondary emission area of predetermined non
uniform configuration, means, adapted to be re
sponsive to phase displacements of a pair of al
ternating current voltages from a predetermined
10
,
said areas completely surrounding the other area,
quency of the received waves is equal to' that of
means for translating received waves into a pair
vof modulated wave voltages of equal magnitude
for the condition where the mean frequency of
the received waves is equal to that of a predeter
mined reference frequency, and means respon
sive to instantaneous inequalities of said pair of
voltages for variably deilecting the electron beam
of the demodulator tube in such a manner as to
10 variably sweep the beam across said two areas.
8. In an angle modulated carrier wave receiver,
a Ademodulator of the beam type provided with an
output electrode having at least two secondary
electron emission areas of different predetermined
non-uniform configurations `and of different
emissivities, means for translating received waves
into a pair of modulated wave voltages of equal
magnitude for the condition where the mean
frequency of the received waves is equal to that
normal phase relation, for sweeping the electron 20 of a predetermined reference frequency, means
beam of said tube over said area'thereby to vary
the potential of said output electrode, and means,
responsive to amplitude variation of said alter
nating current voltages, for controlling the in
tensity of said beam in a sense to render .the out
put electrode potential independent of said am
plitude variation.
Y
5. In a receiver of frequency modulated car
rier waves, a. discriminator network for deriving
from received waves a pair of voltages whose rela
tive magnitudes ~are a function of frequency de
viations of the mean frequency of the received
kresponsive to instantaneous inequalities of said
Y pair of voltages for variably deiiecting the elec
tron beam of the demodulator tube in such a
manner as to variably sweep the beam across said
two areas; and means, responsive to carrier am
plitude variation, for controlling the intensity of
said beam in a sense to render output electrode f
>voltage independent of said carrier amplitude
variation.
» 9. In combination with a beam tube of the _type
having an output electrode provided with a sec
ondary emission area of predetermined non-uni
form configuration, means, adapted to be respon
waves with respect to a predetermined reference
sive to'phase displacements of a pair of alter
frequency, means providing a beam of electrons,
nating current voltages from a predetermined
an output electrode provided with a non-uniform
normal phase relation, for sweeping the electron
secondary emission surface adapted to be trav
beam of said tube over said area thereby to vary
ersed by said beam thereby to vary the effective
the potential of said output electrode, and a grid
potential of the output electrode, a pair of beam
in saidrbeam, responsive to amplitude variation
control elements, and means responsive Ito varia
tions in the relative magnitudes of said pair of 40 of 'said alternating current voltages, for control
V ling the intensity of saidbeam in a sense to render
voltages, for differentially biasing said beam con
the output electrode potential independent of
trol elements to control the secondary emissionV
from said surface.
"
6. In combination with a beam tube of the type
having a target provided with asecondary emis
sion area of predetermined non-uniform con
figuration, means, adapted to be responsive to
said amplitude variation. - '
Y
'
`10. In a receiver of frequency modulated car
45 rierL waves, a discriminator network for deriving
from .received waves a pair of voltages whose
relative magnitudes are a function of frequency y
deviations of the mean frequency of the received
phase displacements of a pair of alternating cur
waves with respect to a predetermined refer
rent voltages from> a predetermined normal phase
relation, for sweeping the electron beam of said 50 ence frequency, means providing a beam of elec
trons, an output electrode provided with a non
V _ tube over said area thereby to vary the potential
uniform secondary emission surface adapted to
of said output electrode, and means responsive to
be traversed by said beam thereby to vary the
the amplitude of at least one of said alternating
effective potential of the output electrode, and
current voltages for controlling the intensity of
`a pair of beam control elements, responsive to
the electron beam.
`
,
'7. In an angle modulated carrier wave receiver, `~variations in the relative magnitudes of said
a demodulator of the beam tube typeprovided „ Vpair of voltages, to control the secondary emis
with an output electrode having at least two sec- Y sion from said surface.
ondary electron emission areas of different emis
GEORGE CLIFFORD SZIKLAI.
sivities and different non-uniform shapes, one of 60
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