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Патент USA US2131443

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Sept. 27, 1938.
'
' w. KUMMERER ET AL
2,131,443
SIGNALING
Filed May 16, 1954
2 Sheets-Sheet 1
~F7l29 I i
114
5/6/1/415
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MODULA?/VG
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4
INVENTOR
01/00
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W/U/ELM mam/m5?
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ATTORNEY
Sept. 27, 1938.
w, KUMMERER ET AL
2,131,443
SIGNALING
Filed May 16, 1934
2 Sheets-Sheet 2
CARR/67?
W4l/E
‘SOURCE .
16
O/RECT CURRENT SOURCE
F1945
14
#LT gm
INVENTOR
' Mil/ELM lfl/MME/Pf/P
ATTORNEY
Patented Sept. 27, 1938
‘ 2,131,443:
UNITED STATES PATENT OFFICE
2,131,443
SIGNALING
Wilhelm Kummerer and Rudolf Giirtler, Berlin,
Germany, assignors to Telefunken Gesellschaft'
fiir Drahtlcse Telegraphic m. b. H., Berlin, Ger
many, a corporation of Germany
Application May 16, 1934, Serial No. 725,846
In Germany May 18, 1933
10 Claims.
This invention relates to an arrangement to
change grid biasing voltage in tube circuits as
a function of the signal strength.
In a great number of electric circuits compris
5 ing tubes it is desirable that the static value of
the voltage of a tube stage should adjust itself
in a de?nite way as a function of the signal
strength or an electrical quantity controlled or
governed thereby.
(01. 179-171)
is controlled by controlling the static voltage on
the grid of the modulator in accordance with
energy characteristic of the modulating poten:
tial amplitudes; while
'
Figs. 4 and 5 are modi?cations of a portion
of the controlling circuits of Figs. 1, 2. and 3. ~
The signal amplitude or else a voltage which
is a function thereof, is impressed upon the ter
The general requirement in
minals I, 2, of the arrangement shown in Fig
10 cases like these is that in the presence of signal
ure 1. By means of the recti?er 4 there is pro
amplitudes falling below a certain minimum
limit or level, the static value of the voltage of
a tube, say, the grid biasing voltage, should have
a selected constant, while being also constant
15 and of higher value in the presence of ampli
tudes above a de?nite upper limit. For signal
amplitudes located midway between the said two
duced across the terminals of capacity 6 a'direct
limiting values, the said biasing voltage is to
adjust itself as a function of the signal ampli
20 tude.
Now, according to this invention, control of
the static voltage value to be acted upon is in
sured by utilizing the fall of potential in a re
sistance caused by the plate direct current of an
2 Ch
auxiliary tube, there being provided in the grid
circuit of the said auxiliary tube an additional
resistance in series with a recti?er which is given
a negative biasing voltage, across which addi
tional resistance current of the recti?er con
3 O trolled by the signal currents produces a poten
tial which is a function of the signal amplitude.
The novel features of the invention have been
pointed out in the claims attached hereto as
required by law.
'
\
The nature of my invention and the operation
\thereof will be better understood from the fol
lowing detailed description thereof and there
- from. when read in connection with the attached
4
drawings in which; Figures 1 to 5 inclusive are
circuit diagrams of embodiments of the invention.
Fig. 1 illustrates a system wherein the static
voltage applied to the grid of a thermionic tube
is controlled in accordance with the amplitude
10
current voltage which isnegative with respect
to the grid of the tube 9-, the said direct current
voltage acting, through its control of the grid
potential, upon the plate current of the tube 9 15
?owing through the resistance Ill, thereby in
?uencing the fall of voltage across the resistance
NJ, to which generally a condenser II is con
nected in parallel, and consequently across the
terminals I4, 15. The potential drop across I4, 20
I5, is caused to act in the grid circuitof the
particular stage whose grid biasing voltage is to
be a function of‘the signal strength in a way as
has hereinbefore been indicated. As a general
rule, the grid circuit also contains in series with 25
l4, l5, a direct current source IS. The static
value of anode current of the tube 9, apart from
the direct current caused by the voltage of source
l2, and the plate resistance I0, is further a func
tion of the size of the biasing voltage of source
8. If desired, the source of biasing potential 8
may be dispensed with.
In the case of all voltages across I, 2, whose
amplitude falls below a predetermined critical
negative biasing potential of the recti?er 4 as 35
adjusted at the source of direct current potential
5, the said recti?er will be blocked so that no
direct current voltage will arise across the con
denser 6. The grid bias is now supplied wholly
by source 8. The consequence is that the work
ing point of the tube will not be shifted by sig
nals of amplitude below said critical value, and
40
Fig. 2 illustrates a practical arrangement
wherein the static bias on the control grid of a
carrier wave modulator of the grid modulation
.thus the voltage across [0 remains constant. It
is only in the presence of signal amplitudes which
exceed the said lower critical value that the 45
source 5 is overcome so that the recti?er 4 be
comes conductive; and there arises across the
type is controlled in accordance with the ampli
tude or percentage of modulation of the modu
lated energy derived from an ampli?er energized
capacity 6 a potential which, according to its
size, diminishes the plate current of tube 9 and
thereby the fall of potential acrossthe resistance 50
by the controlled modulator;
I0. In the presence of the selected critical maximum signal strength the direct current voltage
arising at vt is so high that. the tube 9 is out off
or is blocked, no current ?ows-through Sand the
of signal potentials;
'
Fig. 3 is a modi?cation of the arrangement,
of Fig. 2. In the arrangement of Fig. 3, the con
trolling potentials are derived from the modu
55 , lating potentials and the carrier wave amplitude
potential drop across to will be -of.zero value. 55v
2
2,131,443
Signals which exceed the said upper limit will,
to be sure, cause a higher direct current voltage
across the terminals of 6; but since the tube 9
is already blocked and the voltage at I4, I5 is
zero, it follows that the grid biasing voltage of
the above mentioned tube connected to I4, I5
will not be altered by these signal potentials.
One practical application of the invention is
illustrated in Figure 2. In this case the arrange-_
10 ment hereinbefore described serves the purpose
to lessen the distortions occasioned by the curved
portions of the modulation characteristic in a
transmitter. The plate direct current of tube I8
is conducted by way of the resistance I3. The
15 resistance I9 which is traversed by the plate cur
rent of the auxiliary tube 9 is connected in series
with the source of voltage I6 and- the modulation
transformer I‘! in the grid circuit of the tube I9.
The source I6 and/or resistance I I) shifts the
20 working point of the tube I9 into thelower por
tion of its characteristic curve so that the tube
is working in the region of and above the lower
knee. In lieu of the voltage sources 5 and 8 of
Figure 1, the biasing voltage 5a is provided in
the circuit scheme of Figure 2. The resistance ‘Ia
as a general rule is high compared with the re
sistance I3 and the internal resistance of the
valve 4. By the plate current of the tube 9 an
additional biasing voltage for the tube I9 is
30 occasioned across the external resistance II]. In
asmuch as the plate direct current of the tube I8
grows with the amplitude of the alternating cur
rent amplitude or the percentage of modulation,
it will be seen that also the potential across the
35 resistance I3 will increase. If then, in the course
of operation of the modulator circuit the admis
sible modulation percentage is extended or in
creased, so that the wave amplitudes grow to such
degree that they extend as far as the lower knee
40 of the characteristic curve. of tube I8, there is
produced a growth of the plate current of the
tube I8 and also due to the said recti?cation in
tube I8 the same is negatively biased to a corre
sponding degree. Due to increase in plate cur
45 rent in I8 the fall of potential across the resist
ance I3 in the plate-to-cathode circuit of I8 also
grows. Past a certain point, the potential drop
across resistance I3 will exceed the electromotive
force produced by source 5a and the recti?er 4
50 will become conductive. This permits the nega
tive biasing voltage produced across resistance I3
to reach the grid of tube 9. Consequently, the
plate current through 9 and the ‘voltage pro
duced by the potential drop across the resistance
55 I0 are both diminished.
The resultant biasing
voltage of the tube I9 becomes less negative and
the working point of tube I9 climbs up along the
characteristic curve. A working point located
above the lower bend at closer proximity to the
middle of the characteristic curve results in 'a
greater freedom from distortion. My novel cir
cuit insures operation of the tube I9 at such
working point. The arrangement is so dimen
sioned in this instance that the valve 4 remains
65 blocked as long as the operation takes place
somewhere above the lower bend of the charac
teristic curve upon the rectilinear part of the
modulation characteristic.
And for the same
length of time, also the grid biasing voltage will
70 remain constant in the tube I9. In other words
this modulation percentage is exceeded with the
result that operation takes place in the curved
portion of the modulation characteristic,,then
the fall of potential across I3 will go beyond and
exceed the biasing‘ voltage 5a, the valve 4 becomes
conducting and the higher voltage from I3 will
reach and become active at the grid of tube 9,
with the result that the plate current decreases
and therewith the fall of potential across Ill and
thus the biasing voltage of the tube I9. As a re
sult the latter will be modulated to a higher de
gree or percentage, as the alternating current
amplitude grows, and the modulation character
istic of the tube I9 becomes straighter. In other
words, inside certain limits a correction of the 10
distortion is brought about. By choosing dimen
sions appropriately, conditions may be so made
that in the presence of 100% modulation the tube
9 will just be blocked. In that case the fall of
voltage across I0 becomes zero, .and the biasing
voltage of the tube I9 can not be changed any
further. When the plate current in I8 assumes
larger values, this will cause no additional e?ect
upon the tube I 9 because the lower negative bias
ing voltage of I9 is limited by the source I6.
Another exempli?ed embodiment of the basic
idea of the invention is illustrated in Figure 3.
This is the fundamental scheme of the modula~
tion stage of a transmitter of the thermionic
tube type whose carrier is controlled or modu
lated in proportion to the signal strength. For
the purpose of insuring carrier control recourse
is had fundamentally to a scheme of the kind
shown in Figure 1 which in the present instance
is somewhat expanded and developed for the sake
of example. The signal voltage is impressed upon
the terminals I and 2, and on the transformer
I'I. When the amplitude of the signal voltage is
at a low critical value, or below, recti?er 4 is
blocked by the source 5 and the bias potential
on the grid of 9 is due substantially solely to the
voltage of Ba as modi?ed by resistors 20, etc., and
9 is conductive. Plate current ?owing through 9
and through resistance I9 produces a potential
drop in ID. The potential drop in II] adds to the
voltage of source I6, as in Figure l, and the plate
current through I9 falls. Now, if the modulat
ing voltage amplitude equals a critical value, or
more, the recti?er valve 4 becomes conductive
and current flows in the resistance ‘I producing a
voltage drop which modi?es the potential sup
plied from 8a to bias the grid of 9 more negative,
25
30
35
40
45
thereby lowering 9’s conductivity and reducing
the flow of current through ID. This makes the
control grid of I9 less negative and increases the 50
?ow of plate current in I9. In this manner we
produce across the resistance II] a fall of poten
tial which is a function of the signal strength.
The size of the capacities 6 and II and of the
resistances ‘I and I0 govern the particular rate of
speed» at which the direct current voltage across
I4, I 5, will increase and diminish. Contradistinct
to known circuit schemes used for the control of
the carrier wave, it is possible in the present in
vention to adjust to a large extent the speed of
carrier growth regardless and independently of
the rate of speed of the reduction of the carrier.
If the ripples of the direct current voltage
across I 4, I5 can not be sui?ciently suppressed or
smoothed by the capacities 6 and II seeing that 65
the values of the latter can not be raised ad
libitum because of the resultant time-constants,
it would be recommendable to use ?lter circuits
of the kind as shown, for instance, in Figure 3
where instead of 6 the ?lter circuit 6, 2|, 22 is 70
connected.
. Figure 3 shows a further development of the
arrangement residing in the provision of the re
sistance 29 which is traversed by the plate cur
rent of tube 9 and which is included in the grid
3.,
2,131,443
circuit of the tube 9, said resistance serving the
purpose of compensating the curvature of the
characteristic of the tube 9. The said resistance
device having a controlling electrode and a cath
ode, a circuit applying carrier wave energy to said
controlling electrode, a source of modulating po
will have to be used whenever the desideratum is
tentials, an impedance and a source of direct cur
to insure as linear as feasible an interrelationship
rent potential connecting said source of modulat
between the signal amplitude across I and 2, and
the biasing voltage across M and I5.
ing potentials between the controlling electrode
and cathode of said ?rst named device, a recti
her having input electrodes energized by said
Cases may arise in which the voltage across
the resistance I0 is not desired to bear a linear
10 dependence upon the signal amplitude. In that
instance, at the point marked 9 one or more tubes
possessing suitable characteristics are provided.
Also the frequency curve of the transformer 3
may be so chosen that between the signal ampli
15 tude across I, 2, and the voltage across l4, it, the
desired non-linear relationship will be ful?lled.
The lower and the upper limit or levels depend
upon the choice of the recti?er bias, in Figures 1
and 3, and the turn-ratio of the transformer 3 or
20 the adjustment of the potentiometer l3, in Fig
ure 3. Hence, what is essential is that the volt
age at 5 and in some suitable manner also the
ratio of transformation of the applied voltage
and the one transferred to the recti?er should be
25 adjustable.
modulating potentials, an additionaltube hav
ing an anode, a cathode, and a controlling elec
trode, a second impedance, a ?lter circuit con
necting the output electrodes of said recti?er with
said second impedance, a connection between said
second named impedance and the controlling
electrode and cathode of said additional tube,
and a connection between the anode and cathode
of said additional tube and said ?rst named
impedance.
7
3. In a modulation system, an electron dis
charge modulating device having electrodes in- '
eluding input electrodes on which wave energy to
be modulated is impressed, a source of modulat
ing potentials connected with an electrode in said
device and means to regulate the static value of
the operating ‘voltages of said device as a func—
If an extensive suppression of the voltage rip
ples is desired, then as illustrated in Figure 4,
two tubes 9, 9a, are connected push-pull fashion
in the grid, while their plates are connected in
30 parallel. The recti?er 4 works upon the capacity
6 and the resistance 1 in the grid circuit of the
tube 9 and upon the capacity 60. and the resist
ance ‘la. in the grid circuit of the tube 9a. The
voltage ripples across to are of opposite phase
35 compared with the voltage ripples across 5 so that
tion of the strength of said modulating poten
tials comprising, an auxiliary'tube having an
The condenser l I may be chosen so small that it
will practically exercise no effect upon the time—
constant under certain circumstances it may be
dispensed with. So far as the dimensioning of
the condensers 6 and 6a and of the resistances 7,
‘la, are concerned there is a good deal of latitude
in the case of this circuit scheme.
current potential in series connected with the
control grid and cathode of said auxiliary tube,
said source of potential being of such avalue and,
they will largely be neutralized at the plate end.
40
When using tubes having their grids connected
45 push-pull fashion the recti?er 4 may be dispensed
with, while the grid biasing Voltage of the tubes
50
9, 9a, which is to be a function of thesignal may
be obtained by means of grid recti?cation. One
exempli?ed embodiment of such an arrangement
is schematically shown in Figure 5. By selection
of the biasing potential 5 and adjustment of the
anode, a cathode and a control grid, at resist
ance connected between the anode and cathode
of said auxiliary tube, a capacity connected in 30
parallel with said resistance, said capacity being
suitable to the frequency of said modulating po
tentials, means for coupling said resistance to
an electrode in said discharge device, the voltage
applied to which is to be regulated, a second re
sistance and a recti?er and a source of direct
so connected as to normally block said recti?er, 40
means for biasing the control grid of said auxil
iary tube relative to its cathode by a potential
such that current normally flows in said auxiliary
tube and ?rst resistance, and a circuit for ap-'
plying energy characteristic of the modulating 45
potentials to the input electrodes of said recti?er
for overcoming said blocking potential when the
amplitude of the modulating potentials exceeds
a selected value.
'
4. A system as recited in claim 3 in which said
potentiometer E3, the upper and the lower con
second resistance connected with the control grid
and cathode of said auxiliary tube is connected
trol limits or levels are ?xed.
with said recti?er by way of a ?ltering circuit
Having thus described my invention and the
55 operation thereof, what I claim is:
1. A signaling system comprising, a thermionic
tube having a control grid and a cathode, a cir
cuit for applying carrier waves to said control
grid, a source of modulating potentials, a trans
60 former having its primary winding connected to
said source of modulating potentials, a resistance
and a source of potential connecting the second
ary winding of said transformer between the con
trol grid and cathode of said ?rst named tube, a
comprising capacity.
65 recti?er having its input electrodes energized by
sistance connected between the anodes and cath
odes of said auxiliary tubes, a capacity con
nected in parallel with said resistance, said ca
said modulating potentials, an additional tube
having an anode, a cathode and a control grid, a
second resistance, a ?lter circuit connecting the
output electrodes of said recti?er in parallel with
70 said second resistance, a connection between said
second resistance and the control grid and cath
'
5. In a modulation system, an electron dis
55
charge modulating device having electrodes in
cluding input electrodes on which wave energy
to be modulated is impressed, a source of modu
lating potentials connected with an electrode in
said device and means to regulate the static value 60
of the operating voltages of said device as a func
tion of the strength of said modulating potentials
comprising, a pair of auxiliary tubes each having
an anode, a cathode and a control grid, a re
65
pacity being suitable to the frequency of said
modulating potentials, means for coupling said
resistance to an electrode in said discharge device,
the voltage applied to which is to be regulated, a
recti?er and a source of direct current potential
ode of said additional tube, and a connection be
tween the anode and cathode of said additional in series connected with the control grid and
.cathode of each of said auxiliary tubes, said
tube and said ?rst named resistance.
source of direct current potential being of such a 75
2.
In
a
signaling
system,
an
electron
discharge
75
4
2,131,443
value and so connected as to normally block said
recti?er, means for biasing said auxiliary tubes
by potentials such that current normally flows in
said auxiliary tubes and ?rst resistance, and a
circuit for applying energy characteristic of the
modulating potentials to the input electrodes of
,said recti?er for overcoming said blocking po
tential when the amplitude of the'modulating po
tentials exceeds a selected value.
6. In a modulating system an electron dis
charge modulating device having electrodes in
cluding input electrodes on which wave energy to
be modulated is impressed, a source of modulating
potentials connected with an electrode in said
device and means to regulate the static value
of the operating voltage applied to an electrode
of said device as a function of the strength of
the modulating potentials comprising a pair of
auxiliary thermionic tubes each having an anode,
20 a cathode and a control grid, a resistance con
necting the anodes and cathodes of said auxil
iary tubes in parallel relation, a circuit for cou
pling said resistance to an electrode in said
modulating device, a circuit connected between
the control grids of said auxiliary tubes, means
for coupling said circuit to said source of modu
lating potentials, a recti?er connecting a point on
said circuit between the control grids of said
auxiliary tubes to the cathodes of said auxiliary
30 tubes, and means connected with said recti?er for
normally blocking said recti?er.
'7. An arrangement as recited in claim 6 in
which the control grid and cathode of each of
said auxiliary tubes is shunted by a resistance and
35 by a condenser and in which direct current po
such that current flows in said tube and re
sistance to produce in said resistance a potential
drop, a source of potential coupling said re
sistance to the control grid and cathode of said
modulator tube to apply therebetween said po
tential drop and potential from said source of
potential, a recti?er having its anode circuit con
nected to the control grid of said auxiliary tube,
said recti?er being normally biased to cut off,
and means for applying moduated wave energy
from said ?rst tube to the input electrodes of said
recti?er to control the conductivity thereof.
9.,In a modulating system, an electron dis
charge modulator device having a control elec
trode and a cathode and an output electrode from
which modulated energy is derived, a source of
wave energy coupled to said control electrode, a
source of signal voltage coupled to an electrode
in said device, and means to regulate the static
value of the operating voltage applied to the con
trol electrode of said electron discharge device
as a function of the amplitude of the signal voltage
to be impressed on an electrode of said device and
to limit said regulating action between upper and
lower voltage amplitudes comprising a source of 25
biasing potential and an impedance for applying
to said control electrode relative to said cathode of
said device a selected biasing potential, means
for changing said biasing potential when the
amplitude of said signal voltage exceeds a se 30
lected critical lower value commensurate with said
selected biasing potential, said last named means
comprising an additional discharge device hav
ing output electrodes connected to said impedance
and having input electrodes, a recti?er having an
tentials are applied to the anodes of said auxiliary
output connected to the input electrodes of said
tubes to charge the said anodes relative to the
additional discharge device and an input excited
cathodes by potentials such that said auxiliary
tubes are conductive in the absence of signals to
by voltages characteristic of said signal voltages,
and means for normally biasing said recti?er to
out off in the presence of signal voltages equal to 40
be ampli?ed.
‘
8. In a modulation system a thermionic modu
lator tube having electrodes including a control
grid and cathode, a source of wave energy to be
modulated and a source of modulating potentials’
45 coupled to said control grid and cathode and
means to regulate the static value of the biasing
potential applied to the control grid of said
thermionic modulator tube as a function of the
strength of the modulating potentials comprising,
an auxiliary tube having an anode, a cathode and
a control grid, a resistance connected between
the anode and cathode of said auxiliary tube,
means for biasing said control grid of said auxil
iary tube relative to its cathode by a potential
or lower than said selected critical value.
10. A system as recited in claim 9 including
means for rendering said means for changing
said selected biasing potential inoperative when
said voltages characteristic of signal voltages ex
ceed a predetermined upper amplitude value 45
whereby the biasing potential on said control elec
trode of said ?rst discharge device is controlled
in accordance with the amplitude of said voltages
characteristic of signals between said upper and
50
lower limits.
WILHELM KUMMIERER.
RUDOLF GI'JRTLER.
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