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Патент USA US2407660

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Sep@o 17, 194e;
_
M_ FUCHS
2,407,659
PHASE COMPARISON SYSTEM
l
Filed Feb. 17, 1945
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INVENTOIL
Mo/Pro/v fac/fs
BY
2,407,659
Patented Sept. 17, 1946
UNITED STATES PAT-‘ENT OFFICE
PHASE COMPARISON SYSTEM
MortonvFuchs, NewYork,
Y., -`-assignorfto Fed
eral Telephone vand Radio Corporation, New _
York, N. Y., a corporation of Delaware
Application February 17, 1945, Serial No. 578;'191 '
12 Claims.
.
(c1. A25u-.11)
l
y ,In directionally shiftable radiant acting sys
becomes impossible to correlate andsynchronize
the indicating device of the direction finding re
ceiver with the consequently irregular shifting
ofthe maximum or null of the resulting radiant
tems, used either as direction finders or as rotary
action pattern.
beacons, systems have been proposed wherein the
directive pattern is shifted through a predeter
Another object of the present invention'is the
provision of a -phase comparison direction find
This invention 'relates to phase-comparison sys
tems, particularly those adapted to be used for
direction finding purposes.
mined angular relationship by means of a phase
shifting network shifting the phase relationship
of two or more vradiant acting means with respect
_to a given translating device, such as a trans
mitter or a receiver. In certain of such systems,
transmission lines (usually artiñcial) are coupled
toantennas, and the direction finding receiver is
coupled to said transmission lines at continu
ously. shifting points along said lines to produce
effective shifting of the »phase and consequently
of the radiant action patterns of said antennas
without requiring physical movement thereof.
_
An object of the present invention is the pro- '
vision of an improved shiftable radiant acting
system, such as for example of the types herein
above described.
When such systems are used in direction ñnders
they require an excellent match between the
Y
I
~Ã
n
v
ingH-system‘using matched resistive load terminations for the transmission Ylines along which
lines coupling of the receiver to successive vpoints
produces corresponding shifts in directions of the
nulls ofthe radiant action patterns.
Ideally the foregoing object is accomplished,
according to my invention, by having the means
coupling the transmission lines to the Vdirection
ñnding receiver oiîer infinite impedance to cur
rent from said >lines at the-nulls, that is, when
the voltages‘at the coupling points of each of the
transmission lines are in phase and equal. Un
der null conditions no current will be drawn from
the lines, the lines remain ñat and the null points
onthe line are accurately and regularly spaced
and clear. _,
I When such voltages are unequal and/or out of
phase said'means preferably olîers moderate re
sistive impedance and good power transfer.
vphase shifting transmission -lines and their ter
Under this'condition the flow of current from
minations in order to obtain an electrically flat
the' transmission line to the direction finding re
line along which the phase varies linearly.
ceiver both mismatches and unbalanoes the trans
When the antennas coupled to the said lines also
serve as terminating impedances, it becomes nec "30 mission lines of the system. While this affects
the rest of the radiation pattern, it is unimpor
essary to match the antennas with the lines. A
tant when the null is being used to determine
system of this type is described in the copending
direction.
vapplication of N. Marchand, Serial No. 553,562,
>~ While the conditions described above are ideal,
filed September 1l, 1944.
' >.Another object of the present invention isa
satisfactory results are obtained when said con
provision of an improved phase comparison direc
tion finding system in which the antennas do
not have to match the transmission lines.
Another object of the present invention is the
provision of an improved phase comparison di
rection finding system which uses matching re
ditions are only approximated. When the volt
ages are in phase and equal it is sufficient if the
impedance of the coupling means be relatively
great compared with that of the transmission
lines. When the voltages are not in phase it is
desirable that the impedance of the coupling
sistive loads to terminate the transmission lines.
means become less.
Phase comparison direction finders using
matching resistive loads to terminate the trans
Another object of the present invention is the
provision in such a system of receiver coupling
means which present an impedance large in re
mission lines Vhave not heretofore proven satis
lation to the impedance of the transmission lines
-factory. Direction indications have been obscure
when the voltages at the coupling points are in
and inaccurate. I have discovered this to be
arpred’eter‘mined phase and amplitude relation
.due to the fact that the direction finding re
ship 'and which present lesser impedances when
ceiver draws current from the transmission lines.
This alters the impedance of the lines, caus 50 said voltages diner from said phase relationship.
According to a feature of my invention I con
ing a mismatch and producing reflections and
nect two spaced antenna units to one end respec
standing Waves. It also unbalances the lines in
tively of two separate transmission lines kand ter
relation to each other. Consequently, instead of
minate the other ends of said lines in matching
a linear shift of phase along the lines, the phase
shift becomes erratic and uncontrollable and it 65 resistive impedances. The transmission lines are
2,407,659
3
4
coupled to a translating apparatus. Means are
provided in association with the transmission
lines for varying the phase of the energy trans
ferred between the translating apparatus and the
two antennas.
In one embodiment this is accom_
one of two matching resistive impedances I I and
I2 which latter` are in turn connected to ground.
Since the sharpest indication of direction is pro
duced by a null indication I arrange the lines
in the manner indicated in the drawing so that
plished by varying the points on the transmis
sion lines to which the translating apparatus is
coupled. In another embodiment this is accom
at the midpoints of artiiicial lines l and 8 there
will normally be a zero or null providing the sig
plished by providing phasers intermediate the f
delined by the antenna systems. If the energy
arrives at some other angle, so that antennas I
antennas and the transmission lines coupled to.
the translating apparatus.
In accordance with my invention I interpose a
circuit means between the translating apparatus
and the transmission lines whose impedance
varies in accordance with the voltage conditions
prevailing at the coupling points on said trans
mission lines. When said voltages are of a pre
determined phase and amplitude relationship
the impedance of said circuit means is relatively
great compared to the impedance of the trans
mission lines. When said voltages differ fromy
this phase relationship said impedance is less.
nal is approaching at right angles to the plane
’ and 2 are not energized in phase, the null will
occur at some other point along the lines. Arti
ñcial lines 'I and 8 are arranged midway between.
the ends of transmission lines 5 and 5 and serve
together with movable contacts I3 and I4 respec
tively as phase shifting networks.
Contacts I3
and I4 are Yarranged to move together alongY
their respective artiñcial lines and are coupled to
said lines. Artificial lines ‘I and 8 are preferably
made electrically equal to the spacing between
antennas I and 2 so that a complete effective
rotation of the directive action of the system
In the output of the translator arrangement an
may be obtained. Contacts I3 and I4 are con
indicator may be provided producing a trace line
nected over coupling lines I5 and I6 respectively
positioned in accordance with the positioning of
to a circuit means I'I, hereinafter described, which
the phase control means. The output energy
in turn is connected to a receiver I8 in the out
from the translating device may be applied to
put of which is provided an indicator I9. Prefer
the indicator to produce deñection of theftrace
ably, indicator I’9 is some form of visual indicator
arrangement such as a cathode ray tube 20 pro
in accordance with the strength of the signals.
The phase shifting is preferably made to occur 30 vided with deñecting means such as a coil 2|.
Drive means 22, which may for example be a
in the form of a sine wave so that directional
shifting of the _radiant action pattern isy made
motor, is coupled over a shaft 23 to a driving
at a uniform rate and the indicator calibration
wheel 24 and over a shaft 25 to a control means
may then be made of a uniform or straight line
indicated by arrow 26 for rotating deflection
scale and will remain in proper calibration for " coil means 2I about the cathode ray tube 20.
all received frequencies.
.
Mounted on wheel» 24 is crank 21 which serves
In the system hereinabove described it is'not
during rotation of wheel 24 to shift contacts I3
necessary that the impedances of the antennas
and I4 regularly backward and forward along
artificial lines ‘I and 8 respectively. If drive
match the impedances of the transmission lines.
Because of the relatively high impedance of the L10 means V22.' operates continuously at a given speed,
circuit means when the voltages at the coupling
contacts I3 and I4 will travel back and forth
points are at a predetermined amplitude and
along their respective artiñcial lines at a speed
phase relationship, at such phase relationship
corresponding to a simple harmonic motion or
relatively little current will flow from the trans
sinusoidally. Accordingly, the phase angle of the
mission lines and since said transmission lines 45 energy transferred from antennas I and 2 to the
are terminated in matching resistive impedances
receiver I8 wil] continuously be varied providing
said lines will be flat and consequently said phase
the phase shift along the artificial lines is reg
relationship will occur at predetermined points
ular, which in turn depends on the lines -being
on the transmission lines bearing a ñxed relation
relectrically flat. Assuming for the moment that
ship to the direction of the null of the radiant v50 the lines are flat, the aforementioned operation
action pattern of the antennas. Thus accurate
-will provide an output in the form of a sine wave'
directional indications will be obtained on the
so that effective regular rotation of the directive
indicator.
action of the pattern from antennas I and 2 will
A better understanding of my invention and the
thus be effected. Since coil 2I rotates in syn
objects and features thereof may be had from 55 chronism with the movement of contacts I3 and
the following particular description thereof made
I4, radial deflection of the cathode ray beam will
with reference to the accompanying drawing in
be made in accordance with the incoming signal
which:
energy so that a pattern 28 dependent upon the
Fig. 1 is a block diagram of a simple direction
direction of a transmission station will be traced
finding receiver unit operating in accordance with 60 on the screen of the cathode ray tube. Since
the principles of my invention.
'
the displacement is linear upon the cathode ray
Fig. 2 is a modified arrangement of the'direc
screen a'permanent calibration may be provided.
tion finding receiver unit illustrated in Fig. 1.
With the relationship outlined, indications will be
Turning first to Fig. 1, two vradiant energy
uniform for all frequencies received.
means, for example antennas -I and 2 are sep 65
In systems of the type described the instan
arated a given distance preferably less than 180
taneous angular position of the trace in cathode
electrical degrees. Antennas I and 2 are coupled
ray tube 2li corresponds to a given position of con
by any suitable means to ends 3 andI `4 respec
tacts I3 and I4 along artiñcial lines ‘I and 8 re
tively of transmission lines 5 and 6. Said trans
spectively. Likewise,'providing the artificial lines
mission lines 5 and 6 may beicomprised entirely
are electrically flat, the instantaneous position
of regular transmission lines or may each con
of contacts I3 and I4 would correspond with a
sist in part of a transmission line and in part
given direction of the resultant radiant action
of artiñcial transmission lines 'I and 8 respec
pattern. Under such conditions rotation of driv
tively. The other ends 9 and ID of transmission
ing wheel 24 would correspondingly rotate the
lines v5 and 6 are each connected in series with ,75 trace of cathode ray tube 20 and the radiant ac
monete
5
tion pattern, thus‘enabling 'obtainingof--accura'te
'direction al~ indications.
`Sinceth’e present direction liinding Ireceiver-is
of the null Vtype it is primarily the 'directi'on'of
the ‘null-‘of the directional npattern and not the
position ofthe vrest 'of said Apattern which must
correspond -with given Ypositions of contacts ‘I3
and "14.
If 'artificial lines ‘I -'and `>8 "are velectrically `flat
and >energy -is received iromfa given'dire'ction “at
a given point `-along 'arti'ñciallines Tand >'8, volt
ages Áappear ‘ equal Ivin famplitude :and "correspond
ing jin phase.
Said ‘point- -is ì herein ' termed ~ a vnull
phasers are in turn «connected to Jtransmission
lines ¿35 l‘and 36 Which-terminate 'in matching
resistive limped'aneesïS'I and -»Tillrespectively. 'One
en‘dlo'f thelimpedanc'es 3'I vand -3'8 is coupled î‘by
means loi Elines 39L and ’4U Vtof-circuitv means ~ Ir'I 'sim
ilar‘ßto 4that described in connection >witli'Fig. 3l,
circuit »means If'I bein'gin turn'co‘nnec-ted ¿to »re
'ceiver llï8 whose output is applied- tolindi‘cator >Il!)
of l`cathode ray tube `ZI). lDeiieotin’g *coil ¿2fI -of
tube ¿2D is driven -by-a driving means AvIII JAwhich
also synchronously :varies phasers '§33 and 34.
Operation of i'the driving means `»changes the
phase "of “the ívoltages lïap'p'earing l on ` lines Í39- and
40 in rela-tion'fto îantennas 3l an'd3`2ian‘d v'conse
point. If the ‘lines ‘remain -iiat’an'd ‘thed-irection
quently
rotates 'the A‘null of >the radiant 'action
from #which energy is received is varied, -'t'.ln'e’niill
pattern of saidantenna‘s. `lAt theesa'meïtpimedriv
point =wi1leorrespondingly vary. As will 'be Aap
ing ‘means 4I, rotating 'deflection coil V2|, ~vthere
parent however, if -said lines v’are 'not ñat "the
by 'correspondingly '-r6tates the -trace off-:cathode
>direction-of lthe null will not~correspond vtzr-'any
ray -_tube 20. ~=`A tra'ceïll-'Z-'such ’asïïilllustrate'd Amay
given position of the contacts `I'3 ‘and t4 ¿because
be produced, With‘the point '43"=tliereof,ßproduced
of the eiifect of the standing lwaves lwhich -will 20 in response gvto equal fand --in 'phase voltages at
alter 4the --phase shift along said lines. As has
lines 39 and r411 and corresponding'tod-theiiiiill,
.been stated herein‘beiore the lineslose 'their filat
indicating the 4direction ¿from 'which energy “fis
‘ness when current is -drawn'from said Vlinesby
being
received.
thereceiver.
While 'Ilhave l¿described the »details of ‘ftwofem
v‘.Iînv accordance with my >invention 'circuit means 25 bodiments
of my VVi-n-wention Y.it is »to be under
-Il'I are-»adapted to prevent ‘the drawing of any
'Stoo'd 'that 'variations inlay ’be made ‘inisuch ‘de
vsubstantial amount of current by the `receiver
ltails as will ’be apparent to 'those ‘versed yin ïthe
when* contacts I'3 and I4 are at a null 'pointgthat
art v»without departing from'theiteachings thereof.
is, when ‘the voltagesat aßgiven'point on arti-licial
For example, various different
Yof .antennas
lines 'Ilan‘d‘ß are equalan'd> in phase.
`This is accomplished 'by arranging coupling
lines I5 and I6 each in series -with coils 29 and
3D respectively of> »circuit »means «I"I. Coils 29
vvand 30 may be-ëarran’ged on »a single form with
or without a core of magnetic material depend- »
ing :on the 'frequencies involved. Coils ï29 and
30 «are as closely Vcoupled as possible and are ar
ranged so that when voltagesequal'and `in phase,
appear vat contacts »I3 and I4, the resultant =cur- y
rents ñowin-g ‘through coils «29 'and 3D produce
fields in said V'coils reenforcing each other. Thus
the e'iïec‘tive inductan‘ce oïf 'each of said coils -is
increased, >thereby increasing the effective 'im
pedance of said coils. Coils 29 y_and 3i! are pro
vided with 'a sufficient lnumber' of 'turns ¿so `that
'the resultant imped'ance's under ‘such conditions
are sufficient to prevent receiver IIB from draw
'and .drivinglmeansïmay îb'e employed. Moreover,
While `my >iinvention `is >"particu-la‘rly :adapted for
use ~in "phase -c'onni’a‘rison `direction finders, the
principles lthereof l’may y,be >applied `to «.priivid'e
phase comparison indications :for 'otherlpurposes
While I have 'shown one circuit means, namely
the coupled coils 29 :and 30 which are adapted to
present -maximum Limpedance to currents result
ing ’from'equal and 1in phase voltages, it is'to be
understood -that `other devices ïfor this îpurpose
may fbe employed. "Instead of contacts I3 «and
yIIL-.other coupling means, such as-capacitivecou
pling, maybe employed. Therefore lits-hould be
distinctly understood `that these illustrations of
my invention are 4given 'merely `by Way, of «ex
ample ‘Tand Inot «as fa :limitation von myj invention
as Yset `forth ¿in Ythe -objects thereof and the »ae
companying‘c'laims.
ing any substantial‘amount o'f current from’ar'ti
What -is `claimed is:
Íicial lines y1 'and 8 and consequently said ¿lines
l. fA-system -for comparing the varying phase
50 vof 'voltages vpresen-t 'on respective transmission
'are then substantially electrically hat.
From the foregoing it will bev seen that "for :any
»lines said lines «termina-ting in their character
given direction from which energy "is received
"istie impedances, comprising, -a translating «de
vvthe' ‘artificial lines will become iÍlaït when contacts
-v-ice, :circuit means coupling said transmission
I3 and I4 reach a point corresponding '.t'o îthe
lines to said device, said vcircuit means-.havingl an
null. Thus the indication of ’the null on cathode
input impedance relatively large 'compa-red tothe
ray tube 20 will correspond with `‘a given direction
transmission line impedance to »voltages >having
from which energy is being received.
a `predetermined amplitude »and phaserelation
Circuit means I'I will obviously oiîer less ~im
ship Yat the -points -at which »said'circ-uit means l’is
pedance to the transfer of energy between arti
coupled to the transmission lines and having a
ñcial lines ‘I and 8 when the voltages at contacts
llesser input impedance to voltages -at saidpoints
`I~'3 and Ill are out of phase since the resultant
differing from said predetermined'phase relation
’current flow through coils`29 and 30 will not pro
duce fields Aof the same :magnitude 1as‘are >pro
duced under null conditions. Consequently the
ship, and means for variably controlling the lplaise
of energy transierred'between said lines-and said
circuit means.
transfer of current from artificial lines 'I and 8 65
2. -A system according Áto claim l, wherein ‘the
will in all probability set up 'standing waves ‘on
said »coupling means includes >a. pair ‘of «closely
Isaid lines at other than the null points, but since
-coupled‘coils serially connected respectively `with
the null is being used for direction indications
¿said transmission lines aand providing reinforcing
this vfact does not interfere with accurate voper
îii'e'lds iin ¿response to equal iin ‘phase voltages in
70
ation ofthe system.
said transmission lines.
Referring now to Fig. 2, another ‘system leni
3. .A system >for indicating the relative ’phase
bodying my invention is there disclosed. The
‘of `energy in two sources comprising a translating
antenna elements may consist of dipoles `3'I 'and
device, 'means `for coupling said sources to said
32 which are coupled to variable phasers of 'any
translating
'device comprising’a `pair of 'transmise
suitable typev 33 and 34 respectively. -Said 75
7
2,407,659
sion lines each coupled to one of said sources,
matching impedances terminating each of said
transmission lines, circuit means coupling said
transmission lines to said device, said circuit
means having an input impedance relatively large
compared to the transmission line impedance to
voltages having a predetermined amplitude and
phase relationship at the points at which said
circuit means is coupled to the transmission lines
8
along diiferent points thereof to couple said
translating device in variable phase with respect
to said two radiant acting means, said circuit
means having an input impedance relatively large
compared to the transmission line impedance
with respect to voltages having a predetermined
amplitude and phase relationship at thepoints
at which said circuit means is coupled to the
transmission lines and having a lesser input im
and having a lesser-input impedance to voltages 10 pedance with respect to voltages diifering from
at saidA points diñ‘ering from said predetermined
said predetermined phase relationship.
phase relationship, and means for variably con
-8. The system according to claim 5 wherein
trolling the phase of energy transferred between
said circuit means includes a pair of closely
said circuit means and said» two sources.
coupled coils each having >arranged in series be
4. In a directional shiftable radiant vacting '
system including two spaced radiant acting
means and a radiant energy translating device,
means for coupling said radiant acting means to
said radiant energy translating device compris
tween said translatingdevice and one of said
transmission lines, said coils being arranged to
produce reenforcing fields in response to said
voltages having said predetermined amplitude
and phase relationship.
,
ing a pair of transmission lines- each coupled to 20
9. A radio direction finder system comprising
one of said radiant acting means, matchingv re
two space antenna means, a pair of transmission
sistive impedances terminating each of said
transmission lines, said transmission-lines having
a given impedance, circuit means coupling said
transmission lines to said device, said circuit
-means having an input impedance relatively large
compared to the transmission line impedance to
voltages having a predetermined amplitude and
phase relationship at the points at which said
circuit means is vcoupled to the transmission lines
lines each .coupledat one end thereof to one of
said antenna means, a pair of matching imped
ances each terminating one of the other ends of
said transmission lines, a radio receiver means,
circuit means coupled to the input of said re
ceiver means, means continuously variably cou
pling said circuit means to said transmission lines
along different points thereof to couple said re
ceiver in variable phase relationship with respect
and having alesser input impedance to voltages
at said .points differing from-said predetermined
to said two antenna means, and indicator means
phase relationship; and means for variably con
means for producing a trace line on said indicator
trolling the phase of energy transferred between
said circuit means and said two radiant acting
means.
'
5. In a directional shiftable radiant acting
system including two spaced radiant acting
coupled to the output of said receiver means,
means in accordance with the phasing between
said receiver means and said two antenna means,
and means for deiiecting said trace line in re
sponse to energy received in said receiver means,
said circuit means having an input impedance
means and a radiant energy translating device,
relatively large compared to the transmission line
means for coupling said radiant acting means t0 40 impedance with respect to equal, in phase
said radiant energy translating device comprising
voltages l at the points at which said circuit
a pair of transmission lines each coupled to one
means is coupled to the transmission lines and
having a receiver input impedance with respect
to other phase relationships of said voltages, said
indicator means being arranged to produce _a
directional indication in- response to equal,.in
of said radiant acting means, matching imped
ances terminating each of said transmission lines,
said transmission lines having a given impedance,
circuit means coupling said transmission lines to
said device, said circuit means having an input
phase voltages at said coupling points.
impedance relatively large compared to the trans
10. A direction >finding system according to
mission line impedance with respect to equal, in
claim 9, wherein said circuit means includes a
phase voltages at the points at which said cir 50 pair of closely coupled coils each being arranged
cuit means is coupled to the transmission lines
v and having a lesser input impedance With-respect
to voltages of equal amplitude which are out of
in -series between said receiver means and one
of said transmission lines, said coils being ar
ranged-to produce -reenforcing ñelds in response
phase, vand means for variably controlling the
to said equal, in phase voltages.
i
Y
. «
phase of energy transferred between said circuit 55
11. In a directional shiftable radiant acting
means and> said two radiant acting means.
system including two spaced radiant acting
6. The system according to claim 5 wherein
means and a radiant energy translating device,
said circuit means includes a pair of closely cou
means for coupling said radiant acting means to
pled coils eachbeingarranged in series between
said radiant energy translating device compris
said- translating device and one of said transmis 60 ing two phase control means each coupled to one
sion lines,`said coils being arranged to produce
of said radiant acting means, a pair of match- '
reen'forcingy iields in response to said equal, in
ing impedance means, a pair of transmission lines
phase voltages.
Y
7. In a-directional shiftable radiant'acting sy's
tem including two spaced radiant acting means
and a radiant energy translating device, means
for coupling said radiant acting means to said
radiant energy translating device comprising a
pair of-transmission lines each coupled to one 0f
said lradiant acting means matching impedances
terminating each of said transmission lines, said `
transmission -lines having a vgiven impedance,
circuit means, coupled to said translating de-vice, and means continuously variably coupling
said> circuit means to said. v.transmission lines
each »having one end thereof coupled to one of
said phase-control means and the other end
thereof terminating in one of said impedance
transmission lines having a given impedance, cir
cuit means coupling said transmission lines to
said device, said circuit means having an input
impedance relatively large compared to the trans
mission line impedance with respect to equal, in
phase voltages at the points at which said cir
cuit means is coupled to the transmission lines
and a lesser input impedance with respect to said
voltages in outer phase relation and means for
simultaneously controlling both said phase _con
2,407,659
trol means to vary the phase relation of the
translating device in relation to both said radiant
acting means.
12. In a radio direction ñnder system includ
ing two spaced radiant acting means and a direc
circuit means having an input impedance rela
tively large compared to the transmission line
impedance With respect to equal, in phase
voltages at the points at which said circuit means
is coupled to the transmission lines and having
a lesser input impedance with respect to said
voltages out of phase, means for simultaneously
controlling both said phase control means to vary
tion finding receiver means to said radiant acting
means comprising two phase control means each
coupled to one of said radiant acting means, a
the phase relation of the receiver means to both
pair oi resistive impedance means, a pair of
said radiant acting means, and an indicator
10
transmission lines each having one end thereof
coupled to the output of said receiver and arcoupled to one of said phase control means and
ranged to produce an indication in response to
the other end thereof terminating in one of said
said equal, in phase voltages.
impedance means, said transmission lines having
a given impedance, circuit means coupling said
MORTON FUCHS.
transmission lnes to said receiver means, said 15
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