Fell 26, 1946-
H. v. ALEXANDERSSON r-:T AL,
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2,395,708
REMOTE CONTROL SYSTEM
Filed May 8. 1940
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H. V. ÁLEXÄNDERSSÜN ET AL
REMOTE CONTROL SYSTEM
Filed May 8. 1940
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ATTORNEY
Feb- 25? 1946-
H. V. ALEXANDERSSON ET AL
2,395,708
REMOTE CONTROL SYSTEM
Filed May 8, 1940
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Feb. 26, 194:6a
H. v. ALEXANDERSSON ET AL
2,395,708
REMOTE CONTROL SYSTEM
Filed May 8, 1940
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Patented Feb. 26, 1946
2,395,708
UNITED STATES PATENT OFFICE
2,395,708
REMOTE CONTROL SYSTEM
Harald Valdemar Alexandersson and Carl-Erik
Granqvist, Stockholm, Sweden, assignors to
Aga-Baltic Radio Aktiebolag, ' Stockholm,
Sweden, a corporation of Sweden
Application May 8, 1940, Serial No. 333,926
'
In Sweden May 24, 1939
14 Claims.
( Cl. 172-239)
In remote control systems of the variable fre
tates a further 360°, thereby repeating the same
quency type in which the transmitted frequency
frequencies, the frequency-meter must again
isa function of the position of an object at the
be brought into its initial position, a problem
transmitter, and in which the receiver contains
which is rather difficult to solve, if the frequency
a frequency-meter or other similar device which
takes a position dependent upon the received
frequency, there is diiliculty in obtaining suñi- ‘
meter is also used as driving means for the re
ceiver object. During the overlapping move
ment in question there is such unreliability in
the coincidence between the transmitter and the
receiver, that the operation of the receiver may
cient precision, particularly in cases where a
large angular movement is to be transmitted.
In remote control systems of this type, the ob 10 be very inaccurate.
ject at the transmitter, the angular movement
Furthermore, there is also a risk of error in
of which is to be reproduced at a remote posi
I tion, is connected toa means to control the fre
that it is never certain that the transmitter ob
ject and the receiver object have passed through
quency transmitted which may, for example, be
the same number of revolutions. If, for exam
15 ple, the receiver, for some reason, should become
a frequency of the order of radio frequencies.
The receiver is provided with‘means selective
uncoupled while the transmitter rotates one or
for frequencies of different ranges, which, in the
more turns, the receiver would, when again
simplest case, may constitute frequency-meters
coupled in, show the correct angular position,
An improved form of receiver includes an 0s
but would not have made the correct number
cillator together with a tuning circuit the tuning 20 of turns and there would be no possibility of
supervision unless the receiver wereI provided
also drives the controlled object. A discrimi
with an indicator to show the number of turns
nator is provided for comparing the received
from its initial position.
frequency with the oscillator frequency generated
The present invention relates to an arrange- `
in the receiver and the motor is connected to 25 ment for overcoming the above disadvantages.
tune the oscillator frequency to a value which
In accordance with the present invention the
is a function of the received frequency.
transmitter is arranged so as to sweep over a
As frequency determining means, simple os
plurality of different frequency ranges, for in
stance, two frequency ranges which are sepa
cillation circuits may be used. However, these
have only a limited frequency range which must 30 rated from each other. In this way a more ac
cover the entire range of movement of the trans
curate and continuous control is maintained.
mitter object. On the other hand, the precision
The transmitter may include units responsive to
of the system is determined by the frequency
the two frequency ranges which are operated re
discriminating power of the receiver, which can
spectively over alternate half revolutions of the
not be made too sharp without risk of over
transmitter object or the two units may operate
control and hunting and without risk that the
simultaneously for fine adjustment and coarse
l control Will be unable to follow if there is too
adjustment respectively. In the latter Case the
great a lag between the transmitter and the re
ñne adjustment unit will be connected to have
ceiver. Hence, the precision is reduced as the
a greater range of movement than the coarse
.
range of movement of the transmitter object 40 adjustment unit.
increases.
In the following the invention is described
Within certain fields, especially within the
with reference to the annexed drawings, in
artillery art, it may be necessary to transmit
which Fig. 1 is a wiring diagram of a complete
angles up to 360°, or even up to a multiple of
remote control arrangement according to the in
45
360° with high precision. In such cases the pre
vention, Fig. 2 is a diagram for explanation of
cision usually becomes too small. The precision
the operation of the arrangement according to
can be increased, however, by causing the re
Fig. 1, Fig. 3 is a wiring diagram of a modified
ceiver object to rotate a plurality of times, but
form of thetransmitter, Fig. 4 is a diagram,
this involves certain disadvantages which make
corresponding to the diagram of Fig. 2, for ex
such an arrangement impractical. Assume for 50 planation of the operation of the transmitter
instance, that the receiver organ is a standard
of Fig. 3, and Fig. 5 shows diagrammatically a
frequency-meter. During 360° rotation of the
receiver to be used with the transmitter of Fig. 3.
means of which is controlled by a motor which
transmitter object the frequency-meter will, pro
The transmitter according to Fig. 1 contains
vided it is ,used in the best possible way, sweep
two transmitting units S1 and Sz for transmit
over its entire scale. If the transmitter object ro 55 ting radio frequency within different frequency
2
2,395,708
quency will be displaced in one direction or the
other. Dependent upon the direction in which
the intermediate frequency is displaced, there is
ranges. The tuning means for controlling the
frequency of each of the transmitting units in
cludes condensers C1 and C2, respectively. 'I'he
obtained a stronger field current through one of
two condensers are mounted on the same shaft
as the transmitter object. The shaft also car C1 the two field windings of the motor m. which
causes the motor to rotate, and to turn the con
ries a cam 2 of a switch X, which includes a
densers of the receiver units in a direction to
contact spring I, arranged to be brought, by the
bring the intermediate frequency to the correct
cam 2, alternatively in contact with one or the
value where both of the fields in the motor are
other of two contacts 3 and I. During the rota
tion of the shaft, therefore, the contacts I--3
and the contacts I-I are alternately closed to
connect the condenser C1 and the condenser C2
alternately into the oscillation circuits of the
transmitters S1 and S2.
As will be apparent from the following expla
nation of the operation of the system, it is ad
vantageous, if the Contact arrangement is so
made that one of the contacts is closed immedi
again in balance and the motor stops.'
The operation of the arrangement as a whole is
as follows:
It is assumed that the transmitting unit of the
system is initially in the position shown in Fig. 1.
The movement is further assumed to take place
`in clock-wise-direction. As apparent from the
drawing this rotation of the cam closes the con
tacts l-3 of the switch X and the condenser C1
is coupled in, the transmitter unit S1 therefor
ately before the other is opened and vice versa,
so that the closing of the contacts will always
transmitting a frequency which varies with the
position of the condenser during the rotational
movement. The condenser is cut so that the ca
pacity decreases when turned in clock-wise-di
rection, and therefor the frequency will increase,
as shown in Fig. 2 by the curve a-b. This in
overlap for a short time.
The two transmitting units S1 and S2 are con
nected in parallel by a common line L to the re
ceiver, which consists of two superheterodyne
units M1 and M2, so arranged that one of the
crease of frequency continues during a half rev
receiver units M1 has the same frequency range
olution, and then the switch X uncouples the
as one of the transmitting units S1, and the other
condenser C1 and couples in the condenser C2, so
of the receiving units M2 has the Asame frequency
that the transmitting unit S2 begins to operate.
range as the other transmitting unit S2. The re
ceiving units are only schematically shown, as 30 The transmitting unit S2 transmits within a fre
quency band different from that of the transmit
their construction has nothing to do with the
ting unit S1. Its frequency thus will vary in the
present invention. Concerning the arrangement
manner shown by the curve c-d in Fig. 2, until
and operation of the receiver it is believed to be
after a further half revolution the transmitting
unit S2 is uncoupled and the transmitting unit
S1 is again coupled in.
If the movement takes place very slowly, there
is a possibility that the motor M may not start
immediately upon switching between the two
suiiicient to mention the following:
Each of the receivers contains an oscillator,
the tuning condensers of which C1111 and C1112, re
spectively, are arranged on a common shaft,
which also serves as the shaft of the controlled
object. The control motor m is arranged on this
This motor is provided with two 40 transmitting units. This may be avoided if, as
mentioned above, the operation of both of the
transmitting units is made to overlap during a
motor develops torque in one direction under the
short interval.
iniiuence of one of the field windings and in the
The receiver units are provided with condensers
opposite direction under the influence of the
45 C1111 and C1112, respectively, which are cut in such
other field winding.
a way that they produce the correct intermediate
In the intermediate frequency channel of each
frequency when the controlled object is in the
of the receiving units is arranged a frequency
same shaft.
field windings, wound in such a way that the
same position as the transmitter object. The re
discriminator D1 and D2, respectively, of some
suitable kind, which after rectifying the inter
ceiver condenser C1111 corresponds to the conden
ser C1 of the transmitter unit S1, and the receiver
condenser C1112 corresponds to the condenser C2
of the transmitter unit S2. Due to the above de
scribed operation of the receiver object the re
ceiver will therefor always assume the same posi
tion as the transmitter object,
In order to vary the receiver frequency the
mediate frequency, creates voltages which are a
function of the displacement of the frequency
in the intermediate frequency channel from the
frequency to which the channel is tuned. Thus
each of the discriminators contains two rectiiiers
L11 and L12 and L21 and L22, respectively- The
direct current voltages, obtained from the recti
fiers, are amplified by means of the amplifier
valves R11, R12, R21 and R22, the valves R11 and
R21 being connected in parallel to one of the
usual methods for frequency calibration, known
in the radio art may be used. A very much great
er precision may, however, be obtained, if the
field windings of the motor m and the two other 60 condenser of the transmitter unit as well as of the
receiver unit is designed to cover a greater con
of the amplifier valves being connected to the
trol angle than 180°, e. g. as shown in the fig
other of the two windings.
ure, 270°, the condensers being made to give a
Due to the above described coupling arrange
ment, the superheterodyne receiving units, will
logarithmic frequency variation with the angle of
convert the frequency received from the trans
mitting unit into an immediate frequency, pref
rotation, at least within the range which is used.
One can then always choose an angle of 180°
for the transmitting condensers and a different
erably equal to the difference between the signal
angle for the receiver condensers, at which the
above mentioned frequency relation is present.
frequency of the transmitting unit and -the in
ternal oscillator frequency of the receiver, al
though the sum may be used. If theinternal
In this way a simple condenser of the same shape
is obtained for the transmitter as well as for
oscillatory frequency is correctly tuned, a fre
the receiver while maintaining an accurate align
ment between the angles of rotation of the trans
quency difference will be obtained which is ex
actly the same as the tuning frequency of the
intermediate frequency channel, but if the oscil
lator frequency is wrong the intermediate fre
mitter and of the receiver.
75
»
It is easy to prove mathematically, that in this
asaavos
\,
3
case the inductance coils in parallel to the con
densers should have inductance values which
comes again active, and oscillator 24 is put out
of action.
are in a proportion to each other as the squares
The oscillators 22 and 24 have similar condens
ers. because of the fact that the condensers have
of the mean frequencies of the frequency bands,
respectively. The shunt capacities on the re
ceiver and on the transmitter should be as nearly
a common rotor.
Also the coils 2I and 23 are
similar. 'I'he frequencies therefore will vary in
equal to each other as possible.
'
the manner shown in Fig. 4. The line 30, drawn
After this preliminary explanation of the
in full, represents the frequency of oscillator 29,
operation of a simple system embodying the in
and the line 3I represents the frequency of oscil
ventlon, the transmitter according to Fig. 3 may 10 lator 22 and the line 32 represents the frequency
be described. This transmitter is arranged to
of oscillator 24. Parts of the lines 3| and 32,
provide a main movement and a movement which
which are drawn in full, represent operating pe
is subordinated under this main movement, the '
riods of the respective oscillators, whereas the
last mentioned movement being here supposed
broken parts of these lines represent the time
to be a vernier movement. 'I'he shaft of the 15 while the oscillation circuits of the oscillators are
transmitter object is referred to as I0. This
short-circuited.
shaft may for instance be connected to some
The receiver for the transmitter of Fig. 3 is,
indicator which may be read in a remote place.
shown in Fig. 5` The transmission line is also
Such an indicator is schematically shown at II.
here designated as 25. It is inductively coupled
On the shaft I0 there is arranged a‘worm gear 20 through a transformer 33 to the receiver for the
ing I2, by which the shaft I0 is connected to an
main signal and also through two transformers
other shaft I3 in a gear ratio of 100:1, the last
34 and 35 to each of two cooperating receivers
named shaft determining the main movement.
for receiving the Vernier signal. The main sig
The shaft I0 carries a rotor I4 of a double con
nal receiver consists of an oscillator valve 35
denser, having double stators I5 and I6. Thus 25 connected in a standard manner to operate as a
one condenser is formed between the rotor I4
combined oscillator and modulator. The con
and the stator I5, whereas another condenser
nections for this valve are here of no importance
is formed between the rotor I4 and the stator I6.
except as far as this valve converts the main sig
A :cam wheel Il, carried by the shaft I0, causes
nal frequency to a frequency corresponding to
a contact spring I8 to be in contact with the 30 the difference between the main signal frequency
contact point I9 during substantially half of a
and the oscillator frequency, such as the inter
revolution of the cam I1 and with the contact
mediate frequency in a superheterodyne receiver.
point 2li during substantially the oher half of
The transmitter frequency ‘may have a range of
its revolution.
15G-200 kcs. and the receiver oscillator frequency
'I'he shaft III is grounded, so that the con 35 a range of 250-300 kcs., producing an intermedi
denser I4-I5 is permanently coupled in parallel
ate frequency 100 kcs. Of course the invention
to the coil 2I of an oscillator valve 22, and the
could also ‘be used according to the infrahetero
condenser I4-I5 is in a corresponding manner
dyne principle, although it has not been found
pennanently coupled in parallel with the coil 23
as advantageousof a second oscillator valve 24. The oscilla 40
The oscillator circuit `of the oscillator valve 36
tion circuit, formed by the coil 2| and the con
contains the coil 31, coupled in parallel with a
denser I4-I5 may, however, be short-circuited
trimmer condenser 38 and the tuning condenser
by means of the contacts I3-I9 and in a corre
33. Condenser 39, which is thus the main tuning
sponding way the oscillation circuit of condenser
condenser, is mounted on the same shaft as the>
I4-I6 and coil 23 may be short-circuited by con 45 control motor 4I for the receiver object 42, which'
tacts I8-2II. The anode circuits of the oscilla
is here as a matter of simplicity shown in the form
tor valves 22 and 24 are vinductively coupled to
of a simple dial.
the transmission line 25.
The anode circuit of the oscillator valve con-l
The shaft I3 carries a further condenser, ln
tains a circuit tuned to the exact value of the
This con 50 intermediate frequency and containing th'e con- ,
denser is coupled in parallel to the coil 23 of an
denser 43 and the coil 44. Coil 44 is inductively
oscillator valve 29, the anode circuit of which is
coupled to a second coil 45, tuned by means of
also connected inductively to the transmission
condenser 46.' Further the coils 44 and 45 are
line 25.
connected to each other by means of a condenser
For explanation of the operation of the trans 65 41, which is connected between the mid-point of
mitter, reference is made to Fig. 4. It is assumed
one of the coils, for instance, coil 45, and the
that the shaft I0 turns a plurality of revolutions
high potential end with reference' to alternating
in clock-wise direction. Due to its rotation the
current of th'e other coil, in this case the coil 44.
capacity I4-I 5 will initially increase, so that the
This coupling arrangement is sharply tuned and
frequency 0f the oscillator 22 decreases succes 60 is known per se. It operates in the following
sively. The Áoscillation circit 0f oscillator 24 is
manner:
short-circuited by the contacts I3 and 20. At the
The voltage of a tuned primary circuit and in
same time also shaft I3 turns, but due to the
a tuned secondary circuit are normally displaced
gearing this takes place in counter-clockwise di
in phase by 90°. If the primary voltage is added,
rection and also at a speed which is assumed to 65 as by the condenser 41, to one half of the sec
be only one hundredth of the speed of rotation
ondary voltage in positive direction and to the
of shaft III.> The capacity of condenser 26--21
other half of the secondary voltage in negative
will therefor successively decrease, and the cre
direction, due to th‘e symmetry between these two
ated frequency will increase. When shaft I0 has
voltages the resulting vectors will be exactly equal.
turned half a revolution, the short-circuit of con 70 If the frequency differs from that to which the
denser I4-I6 is opened, so that the oscillator 24
circuits are tuned, however, the symmetry is de
becomes active, and a moment later the oscilla
, stroyed. Of course the two half voltage vectors
tion circuit of oscillator 22 becomes short-cir
of the secondary voltage are still equal, but one
cluding a rotor 26 and a stator 2l.
cuited, this oscillator thereby becoming inactive.
' After a further half revolution condenser 22 be-~ 75
of them, due to the changed phase relation be
tween primary voltage and secondary voltage. will
2,395,708
forman acute angle with the primary voltage
At the same time as the frequency 30, Fig. 4,
vector, whereas the other one forms an obtuse
angle. The former resultant will thereby be es
is transmitted, transmission of a further fre
quency 3| or 32 from the Vernier transmitter takes
place. This is received by means of the receivers
which contain oscillator valves |36 and 233, re
sentially greater than the latter one, and if both _
of the voltages are _rectified different direct cur
rent voltages will be obtained.
'I'h‘e rectifiers, in which the rectification is
made, are in the figure shown as valves 48 and
49, which work on the load resistors 50 and 5|,
spectively. As a matter of fact, the frequency is
received by both of these receivers, but only one
of them is in the position to operate. Assume,
for instance, that the main receiver has been
respectively. The voltages across the respective 10 roughly positioned so that the oscillator |35 op
erates, then due to the characteristic of the dis
load resistors are fed each to one of two direct
criminators of this type a substantial voltage dif
current amplifier valves 52 and 53, the anode cir
ference may be obtained between the direct cur
cuits of which >are connected each to one of the
rent voltages created by rectifiers |43 and |43
field windings 54 and 55 of th'e motor 4 |.
The coupling arrangement for Vernier recep 15 if th'e shaft 56 is not correctly positioned. This
direct current voltage difference influences the
tion is arranged in substantially the same man
field windings of motor 51, so that an automatic
ner as the main receiving system. The only dif
ference is that two cooperating receivers are pro
vided, cne of which responds to the frequency
correction is obtained.
..
Meantime, howeverl the oscillator 235 produces
3| and the other to the frequency 32 in Fig. 4. 20 an intermediate frequency with the incoming
frequency, but this differs widely from the inter
In order to simplify the description the same ref
mediate frequency to which the discriminator is
erence numerals have been used in the Vernier re
tuned. Since discriminators of this kind produce
ceivers as in the main receiver, said reference
very small or no current deviation, when th'e fre
numerals having been increased by one hundred
for one of the Vernier receivers and by two hun 25 quency is widely displaced from the dìscriminator
frequency, the result is that about equally strong
dred for the other.
field currents are delivered by the amplifier Valves
The two receiver units are provided with con
252 and 253 to windings 50 and 6|1 said currents
densers with a common rotor 58, mounted on
also being substantially weaker than the currents
the common control shaft 56, which' is driven bymotor 51. The shaft 56 actuates the receiver ob 30 delivered by Valves |52 and |53. The fact that
the oscillator 236 is allowed to operate at the
ject 59, which is shown as a Vernier dial. The
same time as oscillator |36 therefore does not
anode circuits of the direct current amplifier
cause any appreciable disadvantage.
valves |52 and 252 are connected together and
If necessary, a contact arrangement (not
connected to supply field current to the field wind
shown) may be provided on shaft 55, by means
ing 60 of motor 51, whereas the direct current
of which the field windings 50 and 6| are con
ampliñer valves |53 and 253 are connected to
nected in turn to the valves |52 and |53 and to
gether to supply field current to the field winding
the valves 252 and 253.
6|.
When the system has been out of operation,
The operation of the arrangement is the fol
lowing:
`
40 one can not with certainty assume that the trans
vary as a function of the angular position of the
mitter and receiver are in agreement. It thus
may happen that the receiver or the transmitter
has meantime changed its position, so that a dif
ference in position of half a revolution of shaft
of the sh'aft l0 a full frequency range, corre
within a range of tolerance which is less than
When shaft IU in Fig. 3 turns, it causes the
transmission of two different frequencies, indi
cated by the curves 3| and 32 of Fig. 4, which
shaft I0. Another frequency is transmitted by 45 I0 or a multiple of such' a half revolution has oc
curred. In order to prevent this, the motor 4|
oscillator 29 in the form indicated by the curve
may be made strong enough in relation to the mo
30 in Fig. 4, which is a function of the angular
tor 51 to always secure correct rough adjustment
position of the shaft I3. For each half revolution
sponding to the capacity variation during 180° of 50 plus or minus a quarter of a revolution of the
shaft I0, or the motor 51 may be cut oi! until the
the condenser |4-I5 and |4--|6, respectively, is
motor 4| has completed control within the said
run through by the transmitter units 22 and`24,
tolerance. This may be done by connecting the
as shown in Fig. 4 by curves 3| and 32 respec
field windings 54 and 55 of motor 4| in series
tively.
through the windings 62 and 63 of a differential
On the receiver side the frequency 3D is re
relay 65 having a contact 64. At certain differ
ceived by means of the transformer 33 of the main
ences between the currents through' said wind
receiver, in which it is modulated with’ the fre
ings 62 and 63 the contact 54 of the relay opens
quency created by oscillator valve 36, so that an
the armature circuit of motor 51, which is not
intermediate frequency is formed. vIf it now
should happen that this intermediate frequency 60 closed until the difference between the two cur
rents have decreased to a sufficiently low value.
agrees with the frequency to which the discrimi
Of course it is possible to utilize additional
nator 43-46 is tuned, the reception of th'e fre
stages of Vernier adjustment to obtain a still
quency 30 does not result per se in the operation
more exact adjustment. In this manner it is
of the motor 4| of the receiver. If, however, the
possible to obtain a precision in the remote con
frequency differs from the above, a stronger mag
trol which- is only limited by the mechanical pre~
netizing current is obtained through one of the
cision of the gearing. If the invention is used to
windings 54 and 55 of the motor 4|, which causes
control with high precision the position or di
th'e motor to operate and the shaft 40 is tuned,
rection of some object, for instance, a piece of
until condenser 39 has reached -such a position
that the correct frequency is restored in the in 70 ordnance, the control mechanism of the piece
termediate frequency channel of the main re
may be connected with the shaft 56 as indicated
by th'e dial 59.
ceiver. The dial 42 then will take the position
corresponding to that of the main transmitter,
What we claim is:
but which according to the suppositions may not
`1. In a remote control apparatus, a transmit
75 ter including a pair of units each having means
_ have sufficient precision.
5
2,395,708
for producing and transmitting signals having
powerful to effect control regardless of the ener
gization of the fine control motor.
7. In a remote control system according to
claim 4 in which the signals are respectively in
tended for fine and coarse control, control means
responsive to each of said signals and means
frequencies variable over a predetermined range
and including a control member to control as a
function of its position the frequency of said sig
nal, and a receiver, including a controlled ob
ject, and a pair of units tuned for receiving the
rendering the fine control means ineffective ,until
signals transmitted from said first units, said last
units each having means responsive to variations
the approximately correct coarse control is
in the frequency of the received signal from the
effected by the coarse control means.
8. In a remote control system according to
frequency to which said last units are tuned for 10
effecting a control of said object corresponding to
claim 4, tuning means for the control channels
including variable condensers having logarith
the movement of said control member, said con
mic capacity characteristics.
trol member being connected to cause said first
9. In a remote control system according to
units to alternately transmit signals sweeping
over their respective ranges, whereby said con
claim 4, tuning means for the control channels
including variable condensers having logarithmic trolled object is controlled alternately by the re
ceiver units cf said pair.
capacity characteristics, the, condensers of the
respective channels being angularly displaced rel
2. An apparatus as defined in claim 1 includ
ing a tuning circuit for each of said units of said
ative to each other.
10. In a remote control apparatus, a trans
pair, and a variable condenser having two stators 20
mitter including a unit having means for produc
and a common rotor, one of said stators being in
ing and transmitting a signal having a frequency
cluded- in the tuning circuit of one of said pair of
variable over a given range anda pair of units
- units and the other stator being included in the
having means for producing and transmitting
tuning circuit of the other of said pair of units.
signals having frequencies variable over different
3. A remote control apparatus as defined in
ranges and including a contro1 member to con
claim 1 in which the signals transmitted by the
trol, as a function of its position, the frequencies
units of said pair are variable ,over different
of said signals within the respective ranges, and
ranges.
.
a receiver, including a controlled object, a unit
4. In a remote control apparatus, a transmit
n ,ter including a pair of units having means for 30 tuned for receiving the first-mentioned signal and
producing and transmitting signals having fre
having means responsive to variations in vthe
frequency of said ñrst signal from the frequency
quencies variable over a predetermined range and
which said unit is tuned to receive for effecting
including a control member to control as a func
control of said controlled object, and a pair of
tion of its position the frequency of said signals,
and a receiver, including a controlled object, and 35 units each tuned for receiving said second men
tioned signals, and having means responsive to
a pair of units tuned for receiving the signals
variations in the frequency of said last signals
transmitted from said ñrst units, said last units
from the frequency which said units are tuned to
each having means responsive to variations in the
receive for modifying the control of said object.
frequency of the received signals from the fre
quency to which said last units are tuned for 40
effecting a control of said object corresponding to
th'e movement of said control member, said con
trol member being connected to cause the fre
quency of one of said signals to vary at a rate
substantially greater than that of the other of
11. An apparatus as deñned in claim 10 in .
which said control memberis connected to vary
the frequency of said signals at different rates,
the slower varying frequency constituting a
coarse adjustment of said object and the more
45
said signals and to cause said ñrst signal to suc
cessively sweep over its range while said second
signal varies progressively and continuously in
the same direction during a predetermined range
in movement of said control member whereby
said first signal may be used for effecting ñne ad
justment of said controlled object and said sec
ond signal may be used for effecting coarse ad
iustment thereof.
5. In a remote control apparatus according to
claim 4 in which the signals are respectively in
tended for fine control and coarse control, rotat-~
able tuning means at th'e transmitter and receiver
for each of said signals and reducing gears in
rapidly varying frequency constituting a fine ad
justment of said object.
12._In an apparatus as defined in claim 10.~
means alternately rendering the units ofl said
pair operative, said means being connected to said
control member to cause the signals from said last
units to alternately sweep over their respective
ranges in response to continued movement of
said control member.
13. In an apparatus as defined in claim 10,
means alternately rendering the units of said pair
operative, said means being connected to said
control member to cause the signals from said
last units to alternately sweep over their respec
tive ranges in response to continued movement
terconnecting the rotatable tuning means for the 60 of said control member, said last means causing
the periods of energization of the respective units
ñne and coarse' signals >at the transmitter and
receiver.
of the pair of transmittir g units to overlap where
6. In a remote control apparatus according to
by continuous control is effected thereby.
»‘~
claim 4 in which the signals are respectively in
tended for fine control and coarse control, rotat
able tuning means in the respective channels at
14. An apparatus as defined in claim 10 i
which said second mentioned signals are variable
over the same range as each other, but over a dif
the receiver, and motors actuating said tuning
ferent range from that of the first mentioned
means in response to frequency variations in the
signal.
received signals, the motor actuating th'e tun
ing means for the coarse control being suiiiciently 70
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HARALD VALDEMAR ALEXANDERSSON.
CARL-ERIK GRANQVIST.