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Патент USA US3069651

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Dec. 18, 1962
A. E. BREWSTER
3,069,641
commas AND DECODERS FOR PULSE com: MODULATION SYSTEMS
Filed Feb. 25, 1960
Inventor
A E BRA-‘W575i?
By 5
United States Patent 0
2
1
3,069,641
CODERS AND DECODERS FOR PULSE CODE
MODULATION SYSTEMS
Arthur Edward Brewster, London, England, assignor to
International Standard Electric Corporation, New York,
NY.
Filed Feb. 23, 1960, Ser. No. 10,501
Ciaims priority, application Great Britain Feb. 26, 1959
4 Claims. (Cl. 336-455)
3,069,641
Patented Dec. 18, 196-2
right-hand side of the ?gure corresponds to one of the
cores of the coder referred to above. Actually only six
turns of the spiral are shown, but in practice there will
be many more, for example, about 70. In practice, also,
although the turns are all shown separated, they will be
bunched closely together, and will form a substantially
solid section of the toroid at the left-hand side. On this
portion are wound two windings, namely 2, which is the
sampling winding, and 3, which is the signal wave wind- ’
These two windings .are both shown with two turns,
10 ing.
The present invention relates to a magnetic core assem
and oppositely wound, but each may in practice have
bly such as is applicable to coding and decoding arrange
1 or any other suitable number of turns, and both may
be wound in the same direction.
ments for electric pulse code modulation systems of
7 At the right-hand side of FIG. 1 there is shown a bias
communication.
A number of coding and decoding arrangements em 15 winding 4, the turns of which link different numbers of
ploying suitably Wound cores of saturable magnetic mate
turns of the spiral, and so must pass between these turns
,rial have been proposed, in which one core is provided
as indicated. Likewise four output digit windings 5, 6,
for each signal level to be represented. In order that
7 and 8 are also shown, but it will be understood that
there may be more or less than four such digit windings.
the signal waves may be reproduced with suf?cient ?del
ity, a relatively large number of levels must be provided 20 Each digit winding will link only certain of the turns
of the spiral.
for, and the winding and assembly of the corresponding
FIGS. 2 and 3 show side views at sections of FIG. 1
to indicate how the windings are wound. They are only
The cores have hitherto usually been made from a
diagrammatic, and are not regular sectional views. FIG.
suitable ferrite material, and the ferrite materials avail 25 2 is taken in the neighbourhood of the windings 2 and 4
and FIG. 3 in the neighbourhood of the windings 3 and
able at present place limitations on the switching speed,
and the hysteresis loss is generally inconveniently large.
5 to 8. From FIG. 2 it will be seen that the sampling
winding 2 is an ordinary winding linking all the turns
Certain metallic materials, such as Permalloy, are in prin
ciple more advantageous in these respects, but if the
of the spiral 1, while successive turns of the bias wind
advantages are to be obtained, the corresponding cores 30 ing link 1, 2, 3, etc., turns of the spiral. The reason for
would need to be impracticably small, and this would
this is that the bias ?elds required for successive turns
cores becomes rather an expensive matter, and is not
easily adaptable for an automatic process.
increase the di?iculties associated with applying the wind
of the spiral increase proportionally to the numbers 1, 2,
mgs.
3, 4, etc. It will be clear that if a given bias current be
passed through the winding 4, the innermost turn of the
The object of the invention, therefore, is to provide an
alternative assembly for a magnetic core device, which 35 spiral will be linked by all the turns of the bias winding
and so will have the maximum bias ?eld, while the outer
could, for example, be used in a pulse coder or decoder,
most turn of the spiral is linked by only one turn of the
bias winding 4 and will have the minimum bias ?eld.
On the left-hand side of FIG. 3 is shown the signal
This object is achieved according to the invention by 40 winding 3 which links all the turns of the spiral in the
providing a magnetic core device comprising a toroid
same way as the samp‘ing winding 2. At the righthand
formed by a closely wound spiral of magnetic tape, and
side of FIG. 3 is shown only the digit winding 7. This
is shown as linking the ?rst two turns of the spiral
a winding for carrying a current, a turn of which wind
ing passes between two of the turns of the spiral.
(counting from the inside) and the ?fth turn. This wind
The invention will be described with reference to the 45 ing may also link certain of the other turns of the spiral
and which is suitable for manufacture by an automatic
process and which also enables metallic magnetic mate
rials to be used instead of ferrite materials.
?gures of the accompanying drawing in which:
FIG. 1 shows a plan view of an embodiment of the
invention; and
FIGS. 2 and 3 respectively show side views .at sections
of FIG. 1.
The electrical advantage of using Permalloy, or other
similar alloys, for the magnetic material for the magnetic
Wwe“ ho
which are not shown in FIG. 1. Which turns are linked
will be determined by the code pattern. All the other
digit windings will be applied in the manner shown for
digit winding 7, but will link other combinations of the
turns of the spiral. Thus winding 5 links turn 1 of the
spiral; winding 6 links turns 1, 3 and 5 of the spiral,
and winding 8 links turns 2, 3, and 4. These windings
may also link other turns of the spiral not shown.
cores of a coder is only obtained if the Permalloy is
very thin, either in the form of thin tape, or of deposited
The bias and digit windings will preferably be applied
coatings. It is well known in the art to make a toroidal 55 during the winding of the spiral, which will be done on
core by closely winding a ?at spiral of Permalloy tape.
a central mandrel (not shown). The windings are put
in position whiie the spiral is being wound: thus after
The embodiment of the invention shown in FIG. 1 com
prises such a wound spiral 1, though the turns are shown
each turn of the spiral has been wound, one turn of the
widely separated for clearness. This embodiment also 60 bias winding is taken round through the centre (for
comprises a number of windings for producing the equiv
example through a suitable horizontal slot in the man
alent of the core assembly which determines the quantis
drel), and a wire for each digit winding which should
ing amplitude levels in a pulse coder described, for ex
link the turn is put in position. Then the next turn of
ample, in the speci?cation of co-pending application
the spiral is wound, and the appropriate windings are
Serial No. 819,089, ?led June 9, 1959, and assigned to
the same assignee as is this application. This core assem
bly comprises 70 separate magnetic cores, and each core
has a sampling winding, a signal wave winding, a bias
65 put in place, and so on.
After the bias and digit windings have been put on,
the sampling and signal wave windings 2 and 3 are
winding, and several output digit pulse windings. The
wound on the complete core in the usual way.
These windings processes can be carried out auto—
winding of such a core assembly is a very intricate opera
70 matically by a machine in which the known techniques
tion which has to be done by hand.
In FIG. 1, each turn of the spiral winding 1 at the
of toroidal winding, and weaving, are suitably combined.
It will be seen that the interleaving of the turns of the
space/.21
4
Q.)
spiral by the bias and digit winding wires is quite similar
Furthermore, the type of construction illustrated in
FIG. 1 can be used for other applications besides pulse
coders and decoders. A device called a “trans?uxor,”
used for information storage, comprises a solid toroidal
core of ferromagnetic material through the material of
to a weaving process.
It
be desirable to use a thin ring (not shown) of
suitable non-magnetic material as a foundation on which
the spiral is wound. it is also desirable to begin the ?rst
which one or more small holes are provided parallel to
the axis of the toroid, by means of which holes the mag
netic circuit of the toroid is divided into two or more
turn of the spiral at a point 9 near the position where
the digit and bias windings are to be applied so that the
longest possible are of contact between the ?rst and
parallel magnetic circuits. Windings are threaded through
second turns is obtained before the ?rst turn is linked by
any windings. Alternatively, two or three turns of the
spiral may be put on as a foundation before any inter
leaving occurs, in which case the said two or three turns
may be treated as constituting the “first turn” of the
the small holes which do not pass through the centre of
the toroid. It will be evident to those skilled in the art
that the equivalent of a trans?uXor may be produced by
spiral, as far as the bias and digit windings are con
cerned.
.
It will be understood that the spiral should be as tightly
wound as possible so that the turns will be in contact
throughout the major portion of the circle. The effect
of the interleaving of the windings is to divide the mag
nctic circuit locally into a number of parallel magnetic 10 c.
circuits each of which can be separately biassed and
triggered, and thus each of them corresponds to one
of the cores of the previously proposed arrangement men
tioned above. The magnetic circuits of the outer turns
are, of course, longer than those of the inner turns.
The extreme range of length can, for example, be of
the order of 2:1. It the magnetic circuits are triggered
by using sampling pulses of speci?ed flux linkage as de
scribed in aforesaid copending application, No. 819,089,
the device shown in FIG. 1 by interleaving suitable
windings with the turns of the spiral, and the arrange
ment can provide a much larger number of parallel
magnetic circuits than would be practicable with a trans
?uxor in its ordinary form.
Whilethe principles of the invention have been de
scribed above in connection with speci?c embodiments,
and particular modi?cations thereof, it is to be clearly
understood that this description is made only by way of
example and not as a limitation on the scope of the
invention.
What I claim is:
l. A magnetic core device for use in an electric pulse
coder or decoder, comprising a close'y wound spiral of
magnetic tape forming a ?at toroidal disc, a plurality of
digit windings each of which comprises a conductor
which passes between certain adjacent turns of the spiral
30 in such manner that each digit winding effectively links
this difference in magnetic path length is of small con
sequence. The longer magnetic circuits will require
larger currents to trigger them but these larger currents
will be available if such sampling pulses are used.
While the arrangement shown in FIG. 1 can provide
for 70 levels, for example, in case it is desired to code 0) LI
a signal wave having 35 positive and 35 negative levels,
then it is preferable to use two arrangements according
to FIG. 1, each designed for 35 levels, and they would
then be oppositely biassed.
windings each of which links all the turns of the spiral.
2. A magnetic device comprising:
The assembly shown in FIG. 1 should be as small as 40
a toroidal core consisting of a plurality of closely
is practicable in order to minimise the hysteresis losses.
For example, the core could have an internal diameter
of 0.25 inch, and could be wound with suitable Perm
ailoy tape (1.0005 inch "‘ ' ‘
6.1 inch wide, and
gs could be 46 SWG enram- '
the
elled‘wire
copper
usedwire
for (diameter
the
{2.0924 inch). Then the maxi
mum magnetic path length would be about 1.6 times
the maximum path length in the case of a core which
provides for 35 levels.
The windings could alternatively be wound with thin
insulated copper tape instead of copper wire.
While Permalloy is suggested above as the material
for the magnetic tape, it will be understood that other
magnetic metals or alloys having suitable magnetic char~
acteristics, and capable of being produced in the form
of thin tape, could be used.
it will be evident that since a decoder employing mag
netic cores has digit and other windings similar to those
of a coder, the arrangement of FIG. 1 can be adapted
for a decoder by applying and interleaving the required 60
rindings in the manner described.
only predetermined turns of the spiral, the predetermined
turns of the spiral which are linked being different for
each digit winding, a bias winding having a plurality of
turns and consisting of a conductor which is inte‘leaved
with the turns of the spiral in such manner that different
turns of the bias winding effectively link respectively
different numbers of turns of the spiral, and two further
wound turns of magnetic tape; and
a winding consisting of at least three coils connected
in series, each coil linking a different number of
adjacent turns of said toroidal core.
3. A device according to c’aim 2 comprising a further
winding for carrying a current, and having a plurality
of turns interleaved with the turns of said toroidal core
in such manner that different turns of the said further
winding effectively link respectively diiferent numbers
of turns of said toroidal core.
4-. A device according to claim 2 comprising an addi—
tional winding for carrying a current, which additional
winding links all the turns of said toroidal core.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,849,485
2,284,406
Gibbs et a1. ___________ __ Mar. 5, 1932
D’Entremont _________ __ May 26, 1942
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