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Патент USA US2117680

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May 17, 1938T
y
J. ROBINSON
`WIRELESS RECEIVING SYSTEM
Filed Nov. 2, 1934
2,117,680
-
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May 17, 1938.
J, R0B|N5QN`1
2,117,680 ‘
WIRELESS RECEIVING SYSTEM
Filed NOV. 2, _1954l
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Patented May 17, 1938
d
NiTED STATES PATENT OFFICE
2,117,680
WIRELESS RECEIVING SYSTEM
James Robinson, London, England
Application November 2, 1934, Serial No. 751,205
In Great Britain November 7, 1933
9 Claims. (Cl. IZ50-20)
LTI
This invention is for improvements in or relating to wireless receiving systems and the primary
object of the invention is to provide a high degree
of selectivity in reception more especially for
the reduction of heterodyne interference produced
by the interaction between the carrier wave of the
interference signals obtained from the aerials in
approximately the same phase for the wanted
signals whereby the heterodyne beat interference
signals are combined in out-of phase relationship
and with diminished resultant effect. In one 5
form there iS prOVided means (i. e. Comprising
wanted signals and the carrier waves of the other
signals. By this invention use is made of the
a rectiñer) at each aerial for detecting the
modulation signals and means for transferring
conditions of normal modulated carrier wave
the aerials fOr COmbining the received signals
l0
Wanted and unwanted signals arriving from
dilîerent directions at one of the aerials afore
lated carrier wave transmission” I mean a carrier wave which is interrupted or altered in any
l5 manner according to the intelligence to be transmitted and l: include transmissions in which the
carrier component' is partially or completely suppressed at the transmitter such as single side
band systems and is reinstated at the receiver
20 by a local oscillator or is built up by means 0f
said and closely adjacent as regards their carrier
frequencies produce an undesired heterodyne beat
effect- The same signals arriving at another Of l5
a receiver of low damping,
According to the invention the method of re-
the aerials also produce the same heterodyne beat
note, but there will be a phase difference between
the heterodyne notes produced in the two aerials
due t0 the difference in path distance between
the aerials for the wanted and the unwanted sig- 20
nals. Thus by combining the signals collected at
the several aerials the wanted signals may be
ceiving modulated carrier wave transmissions
ccmbined sensibly arithmetically, Whereas the in
comprises producing a plurality of wave path
dillïerences as between the wanted transmission
and an interfering transmission of such relative
frequency as to cause a heterodyne beat interference, receiving a plurality of portions of the
wanted and interfering signals in different phase
terfering or heterodyne beat eiïects are combined
Vectcl‘ially With the result that the latter intcr- 25
ference is minimized and may fOr all practical
purposes be eliminated- The aerials 0f Which
there may be two or preferably more than tWO
may be spaced in any desired manner and for
'
‘
‘
'
ferences of the transmissions and combining these
portions of the signals in the accumulative sense
for the wanted signals whereby the heterodyne
beat
el’fect is diminished due to the different phase
C? Ci
relationships which consequently occur between
the received portions of the interfering signals.
The invention also comprises the method of
receiving modulated carrier wave transmissions
which comprises receiving on a plurality of spaced
¿o aerials both a wanted signal and an interfering
signal arriving from a differ-ent direction and
producing a heterodyne interference, and com-
bining all the received signals at a single receiver
tp. c;
the received signals to a receiver common to all
1c transmission wherein the transmission frequencies arrive at a receiving system in their normal
phase relationship. By the expression “m0du-
whereby the wanted signals are cumulated but
~ the phase-differences of the various heterodyne
beats at the different aerials causes their total
example may be arranged in a straight line with 3o
unifcrm spacing 0r in a circle.
Accci‘ding t0 a feature 0f the inVentiOn the
signal-accepting means at each 0f the aerials
comprises a frequency ccnverting device for
changing the frequency 0f the carrier-Waye t0 35
ancthcr frequency fOr the transfer 0f the signals
t0 the majcr receiving means ccmmOn t0 all the
aerials- The transfer Of the signals frcm the
signal-accepting means at each aerial t0 the
maier receiving means may be eiïected by means 40
ci lines 0r by means 0f Wireless links using, fOr
cXample, a supcrscnic carrier-frequency fOr this
purpose
Preferably and mcre especially Where the
aerials are spaced ccnsidcrablc distances apart 45
means is prcVided, fOr eXample in each 0f the
effect to be diminished.
connections between the aerials and the major
The invention further comprises a receiving receiving apparatus, fOr the relative adjustment
system for modulated carrier wave transmissions 0f the phase Of the signals fOr the purpose of
50 comprising a plurality of aerials spaced apart, bringing the wanted signals arriving from each 50
selective receiving means of such high order of of the aerials into phase agreement. Further
selectivity as to remove direct interference of more the phase adjusting means may be emplcyed
unwanted transmissions from the signals received, to effect a combination of the wanted signals
means combining the modulation signals com- >which is not truly arithmetioal, in order to reduce
prising the wanted signals and heterodyne beat still further a heterodyne interference resulting, 55
2,117,680
2
ulation. It is of course necessary to subsequently
for instance from wanted and unwanted signals
arriving from closely similar directions.
The invention will further be described with
correct for such distortion.
In operation assuming that the wave front of
signals required to be received is moving in the
reference to the accompanying drawings in which
Figures 1, 2 and 3 show diagrammatically alter
CFI
native systems for carrying out the invention.
In the drawings four aerials I0, II, I2 and I3
are provided spaced any distance apart (e. g. by
a distance of the order of a wavelength ‘of the
signals to be received) and in any symmetrical
direction indicated by the arrows 20 and that of
the interfering signals in the direction indicated
by the arrows 2I and for the purpose of explana
tion that the frequencies of the two transmis-y
sions are such that carrier-Waves of the two 10
transmissions heterodyne to produce in a re
ceiver an audible beat note which is objection
or unsymmetrical arrangement. These aerials
able. Under these circumstances each of the re
ceivers I4 which are tuned to select the required
may either be non-directional or may be’con
structed in any known manner to have directional ‘
signals will also produce beat note interference.
Further assuming that at the aerial II the
characteristics for the purpose hereinafter de
scribed or again they may each be of the multi
relative phase of the carrier wave of the wanted
15
ple type to minimize the effects of fading. At transmission with respect to that of the un
each aerial there is provided >a signal accepting wanted transmission is such as to produce a het
means I4 of any well known form and including
erodyne peak at a given instance. Then at the
in this instance a detector or other equivalent
other aerials the phase relationship of the two 20
means for isolating the modulation frequencies. transmissions will be different depending in this
The modulation signal output from each of the instance solely upon the difference in path of the
receivers I4 is conducted by lines I5 to a main
unwanted and wanted signals. For instance at
receiving station generally indicated at I6. The the aerial I0 the difference in phase will depend
lines I5 are connected through phase adjusting
upon the distance apart of the aerial I0 from the 25
means I1 for each receiver to a main receiving
aerial I I. The wanted signals arrive at the aeri
apparatus indicated at I8 in which the signals als I0 and II simultaneously but the unwanted
received at the several aerials lare combined. The
signals arrive on the two aerials in succession so
receivers I4 are highly selective for the purpose
that if the distance apart of these aerials is for
instance half a wavelength of the unwanted sig 30
of eliminating interference as far as is possible
and may be such as are described in U. S. Patent
nals the resultant beat note produced will be in
No. 1,821,032, dated 1st September, 1931, in order phase opposition to the beat note received from
to obtain substantial freedom from interference the aerial II. The phase relationship of the
due to direct reception of the modulation signals heterodyne beat note received in the separate re
of unwanted transmissions,
Thus the selectivity of the receivers I4 may be
such that there is no response to interfering sig
nals whereof the carrier frequency lies outside
the response curve of the receiver but differs from
the'frequency of the wanted carrier wave by an
amount less than the highest modulation fre
quency of the wanted signal. Such a receiver
embodies means for correcting the inherent sig
nal distortion due to the high selectivity of the
receiver in order that modulations of the carrier
wave of the wanted signal corresponding to its
whole modulation range may be faithfully repro
ceivers will differ as between one receiver and 35
another depending on the distribution of the
aerials for any given transmissions so that by
combining the received signals at a central re
ceiver the heterodyne beat note is suppressed to
a large degree. By combining the received sig
nals at the central receiver the wanted signals
are added together arithmetically or substantial
ly arithmetically because the phase difference be
tween the modulation signals from the several
aerial receivers I4 will be negligibly small except
.for a very wide spacing of the aerials and in
this latter case the wanted signals may be brought
duced. Alternatively, the receivers may be de
scribed as having such high selectivity and/or
low damping that there is no response to inter
into phase agreement by slight adjustments of
fering modulated signals whereof the side band
frequencies differ from the frequency of the
and will thus be combined vectorially so that the
wanted carrier wave by an amount less than the
highest modulation frequency of the wanted sig
nal, modulations of the carrier wave of the want
ed signal corresponding to its whole modulation
range being faithfully reproduced by the aid of
the phase correcting devices I1. The heterodyne
beat notes will be considerably different in phase
resultant is zero or some relatively small value.
In an alternative arrangement the signal ac
cepting means indicated at I4 for each aerial may
comprise for instance a high frequency amplifier 55
to pass on the high frequency signals to the cen
tral receiving station I6 and in this case detec
means for correcting the inherent signal distor
tion due to the high selecticity of the receiver.
tion of the signals from each aerial takes place
It will be understood that the phrase “highest
modulation frequency” is employed to refer to
60 the highest modulation frequency that is consid
bined, for instance in the phase controlling de
vices I'l. In this arrangement it is important
that the paths between the aerials and the main
receiver should be the same or alternatively the
ered necessary for the tolerably good or satisfac
tory reproduction of the signals, as distinct from
such higher frequencies as may be present but of
which the absence from the received signal is not
65
noticeable. The phrase “no response” is em
ployed to indicate that the interference from a
normally modulated transmission is negligibly
small to a normal individual when the wanted
and the interfering signals are of comparable
field strength.
It can be shown that it is a characteristic of
receivers of such high degree of selectivity that
the amplitude of the signal response is inversely
7:5
proportional to the frequency ofthe signal mod
in the main receiver before the signals are com
phase adjusting devices-I1 should be adjusted to
compensate for any differences.
In the ar
rangement previously described with reference
to Figure 1, in which the modulation signals are
transferred from the aerials to the central re
ceiver it is not so essential to control the phase
of the signals before they are combined because '
unless the spacing of the aerials is very large
the effect upon the phase of the modulation sig
nals is very small.
In the case of single side band transmissions
the carrier may be supplied by means of a locally
2,117,680
produced carrier frequency applied to the signals
3
at each of the receiving devices I4, or if a small
percentage of carrier is included in the trans
ing the receiving station at each aerial with the
central receiving station 35.
mitted signals, the receiving devices |4‘may be
of such low damping as to build up this carrier
component to the normal value for the received
signals.
It will be understood that this suppression of
the
heterodyne beat note or a plurality of such
10
The suppression of one side band of the re
ceived signals at the device 33 serves further to
reduce any possible heterodyne interference by
eliminating any interfering frequency occurring
Ul
in the suppressed side band.
The central receiving station 35 comprises a
highly selective receiving means 36 for the sig
nals from each aerial. This receiving means be
ing for example of the kind described in U. S.
Patent No. 1,821,032, dated 1st September, 1931
and comprising essentially a rectifier for isolating
the modulation signals. The modulation signals
15
of the Wanted transmission.
In order further to ensure freedom from heter
odyne interference each of the aerials l0, ll, l2
from each of the devices 36 are passed through 15
31 to a single amplifier
and I3 may be constructed in any known manner
before described with reference to Figure 1 and
thus provide an output at 39 free from interfer 20
ence.
Instead of combining the signals from the sev
eral
'
25
25
30
The
heterodyne interference thus obtained may then
30
be opposed to complete signals received on a sep
:o Ci
suppressing one side band of the received signals,
and signal accepting means 42 including a de
35
tector for isolating the modulating frequencies.
The modulation signal output
'
40 is conducted by lines to a main receiving appa
ratus 44 common to all the aerials through phase
adjusting means 43. In construction the signal
accepting means 42 constitute highly selective
receivers for elminiating, as far as is possible,
45 direct interference due to an unwanted trans
40
mission, and such highly selective receiving appa
ratus may be of the form described in the afore
said Patent No. 1,821,032. 'I‘he loop aerials 40
are adjustable as regards direction in order to
50 provide the best response from Wanted signals
45
fects will be'added vectorially and thus tend to
balance out.
arriving in the direction indicated by the arrows
50
20, and a lesser response from the unwanted
signals arriving in the direction indicated by the
arrows 2l.
The loop aerials 40 are controlled
55 by means of a remote control device 45 located
at the main receiver and connected by lines indi
cated at 46 to the several loop aerials.
In the embodiment of the invention shown in
Figure 2 of the drawings each of a plurality of
60 spaced aerials 3D feeds signal selecting means 3|
'
55
the required
60
signals and the output of the signal selecting
is applied to frequency changing means
32 in which the modulation signals are impressed
upon a carrier Wave of a frequency different from
that of the original carrier wave. The modu
lated carrier wave output from the device 32 is
then applied to a filter 33 for suppressing one side
band of the signals and the remaining side band
and the local carrier wave is transmitted through
a channel indicated at 34 to the central receiv
ing station generally indicated at 35. The chan
65
note produced
70
nel 34 for each aerial may consist of a conduct
ing line as described with reference to Figure 1
or may be constituted by a wireless link connect
75
2,117,680
4
wave transmissions comprising the combination
the heterodyne beat interference signals in ap
proximately the same phase for the wanted sig
nals whereby the heterodyne beat interference
signals are combined in out-of-phase relationship
and with diminished effect.
2. A receiving system ‘for modulating carrier
wave transmissions comprising the combination
of an aerial, selective receiving means at said
aerial tuned for the wanted signals, the selectivity
of said receiving means being such that there is
no response to interfering modulation signals
whereof the carrier frequency lies outside the
response curve of the receiver but differs from
the frequency of the wanted carrier wave by an
of an aerial, selective receiving means at said
aerial tuned for the wanted signals and of such
high order of selectivity as to remove modulation
interference of an unwanted transmission, at
least one additional aerial spaced apart from
the first said aerial and also having selected
receiving means similarly tuned for the wanted
amount less than the highest modulation fre
quency of the wanted signal, at least one addi
tional aerial spaced apart from the first said
aerial and also having selective receiving means
similarly tuned for the wanted signals and of
similar high order of selectivity, said additional
aerial being so spaced from the first said aerial 15
signals and of such high order of selectivity as
15
to remove modulation interference of the un
20
that the heterodyne beat note produced by the
wanted and unwanted signals is different in phase
wanted transmission, said additional aerial being
at the two aerials, and means combining the
so spaced from the ñrst said aerial that the het
erodyne beat note produced by the wanted and
modulation signals. comprising the wanted signals 20
and the heterodyne beat interference signals in
unwantedl signals is different in phase at the
approximately the same phase .for the wanted
two aerials, means to suppress one side band of
signals, whereby the heterodyne beat interference
the signals received at each aerial, and means
signals are combined in out-of-phase relation
combining the modulation signals comprising the
ship and with diminished effect.
wanted signals and the heterodyne beat inter
ference signals in approximately the same phase
25 for the wanted signals whereby the heterodyne
beat interference signals are combined in out-of
phase relationship and with diminished effect.
3. A wireless receiving system for modulated
carrier wave transmissions comprising several
6. A wireless receiving system for modulated 25
carrier wave transmissions comprising several
aerials so spaced with regard to the direction
and wave-length of wanted signals and unwanted
signals that heterodyne beat effects between
30
wanted and unwanted signals are in different
directional aerials indiscriminately spaced apart,
selective receiving means at each aerial similarly
tuned for the wanted signals and of such high
order of selectivity as to remove modulation in
terference of the unwanted transmissions, means
to suppress one side band of the signals received
at each aerial, means combining the modulation
phase at at least two of the aerials, selective re
ceiving means at each aerial similarly tuned for
the wanted signals, the selectivity of said re
ceiving means being such that the amplitude of
the modulation frequencies of the wanted signals
throughout the whole of the modulation fre
signals comprising the wanted signals and the
heterodyne beat interference signals obtained
quency range is relatively altered, said receiving
means including devices for relatively altering
the amplitude of the modulation frequencies in
the opposite sense, and means combining the '-10
from the aerials in approximately the same phase
40 for the wanted signals, whereby the heterodyne
beat interference signals are combined in out
modulation signals comprising the wanted sig
nals and the heterodyne beat interference signals
obtained from the aerials in approximately the
. of-phase relationship and with diminished re
same phase for the wanted signals, whereby the
45
sultant
effect.
4. A receiving
system for modulating carrier
wave transmissions comprising thecombination
heterodyne beat interference signals are corn
of an aerial, selective receiving means at said
'7. A wireless receiving system for modulated
carrier wave transmissions comprising a plurality
aerial tuned for the wanted signals, the selectivity
of said receiving means being such that there is
no response to interfering modulation signals
50 whereof the carrier frequency differs from the
frequency of the wanted carrier wave by an
amount less than the highest modulation fre
quency of the wanted signal, at least one addi
tional aerial spaced apart from the first said
aerial and also having selective receiving means
similarly tuned for the wanted signals and of
such high order of selectivity as to remove modu
lation interference of the unwanted transmission,
said additional aerial being so spaced from the
60 first said aerial that the heterodyne beat note
produced by the wanted and unwanted signals is
diminished resultant effect.
of aerials disposed in spaced relation, and means u
whereby wanted modulation signals intercepted
by said aerials are combined in approximately the
same phase and are reproduced while heterodyne
beat notes between wanted and unwanted signals
intercepted by said aerials are combined in dif
ferent phase and substantially eliminated, said
last named means including selective receiving
means for the signals from said aerials, the selec
tivity of said receiving means being such that
there is no response to interfering modulation
signals whereof the carrier frequency of such
interfering signal differs from the carrier fre
different in phase at the two aerials, a receiving
quency of the wanted signal by an amount less
than the sum of the highest modulation fre
station common to the aerials, a frequency con
quencies of both signals.
verting device at each aerial for changing the
frequency of the carrier-wave to another fre
quency for transfer of the signals to said receiv
ing station, and means at said receiving station
combining the modulation signals comprising the
wanted signals and the heterodyne beat inter
ference signals in approximately the same phase
for the wanted signals whereby the heterodyne
beat interference signals are combined in out-of
phase relationship and with diminished effect.
75
bined in out-of-phase vrelationship and with
5. A receiving system for modulated carrier
8. A wireless receiving system for modulated
carrier wave transmissions comprising a plurality
of aerials disposed in uniformly spaced relation,
and means whereby wanted modulation signals
intercepted by said aerials are combined in ap
proximately the same phase and are reproduced
while heterodyne beat notes between wanted and
unwanted signals intercepted by said aerials are
combined in different phase and substantially
eliminated, said last named means including se
65
2,117,680
5
lective receiving means for the signals from said
aerials, the selectivity of said receiving means
being such that there is no response to Vintervfering modulation signals whereof the carrier
frequency of such interfering signal differs from
the carrier frequency of the wanted signal by an
amount less than the sum of the highest modula-
that there is no response to interfering modula
tion signals whereof the carrier frequency dif
fers from the frequency of the wanted carrier
wave by an amount less than the highest modu
lation frequency of the wanted signal, and means
combining the modulation signals comprising the
Wanted signals and the heterodyne beat inter
tion frequencies of both signals.
_
9. A wireless receiving system for modulated
ference signals obtained from the aerials in ap
proximately the same phase for the Wanted sig
carrier wave transmissions comprising several
aerials disposed in uniformly spaced relation in
a straight line, selective receiving means at each
aerial similarly tuned for the wanted signals, the
selectivity of said receiving means being such
nals, whereby the heterodyne beat interference
signals are combined in out-of-phase relation
ship and with diminished resultant effect.
JAMES ROBINSON.
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