Improvements relating to the Transmission of Signals through Telegraph Lines and Cables.
Year: 1894

page_text: Date of Application, 3rd May, 1894
Complete Specification Left, 4th Feb., 1895-Accepted, 9th Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements relating to the Transmission of Signals through
Telegraph Lines and Cables.
1, JOSEPH ARTHUR LOVEL DEARLOVE, of No. 4 Great Winchester Street, in
the City of London, Assoc. Inst. Elec. Eng. do hereby declare the nature of this
invention to be as follows:-
My invention relates to improvements in the transmission of signals through
telegraph lines aerial, submarine, and subterranean.
According to my invention I employ, in place of the condensers heretofore used,
"transformers" constructed in a manner similar to those now generally in use for
electric lighting purposes with laminated iron and closed magnetic circuit, the coils
being composed of insulated copper wire and so arranged or subdivided that two,
three, four or more distinct and insulated circuits are obtainable. These circuits
are made with an equal number of turns of wire and need not be equal in
resistance to each other, this arrangement allows of the ratio of the turns in the
primary and secondary circuit to be varied as is most suitable.
In the ordinary method of working telegraph cables and lines, condensers are
placed between the cable and battery key and also between the receiving instrument
and earth. I place transformers in equivalent positions, both as regards the
sending and receiving circuits, at each end of the line. The receiving instrument
or battery is placed as desired in connection with one of the transformer circuits
by means of a convenient switch, the two or more circuits on the transformer
being respectively of a primary and secondary character.
Advantages exist in this mode of connection which are not possessed by the
condenser method now in use. When arranged in accordance with this invention
instead of the ends of the line being insulated as with condensers they are to
earth through a comparatively low resistance thus allowing the cable to rapidly
discharge after each application of the battery to the primary circuit. On
applying the battery to the primary circuit the induced charge or current in the
secondary circuit sends the signal to the far end, the amount, of this current
depending on the strength of current in the primary circuit and the ratio of the
turns of wire in the primary to those in the secondary circuit. On breaking the
circuit of the battery and primary a curbing current of opposite sign is sent to
line and thus forms an automatic curb.
In ordinary duplex working on the "bridge system" transformers may take the
place of the condensers now generally employed.
Where, in the case of duplex working, condensers have hitherto been employed
both before the cable and before the artificial line with condensers in the receiving
circuit, I construct my transformer with one or more primary circuits and two or
more secondary circuits in the same closed magnetic circuit and I also place
another transformer in the receiving circuit in a position equivalent to that
heretofore occupied by the condenser.
I may also use the transformer in a sending or receiving circuit of a duplexed
telegraph cable or line in combination with condensers, the condensers being in
the sending circuit and the transformer in the receiving circuit the primary circuit
being joined to the junction of the condenser and cable and to the junction of the
condenser and the artificial line. Or I may transpose the transformer and condenser
placing the former in the sending circuit and the latter in the receiving circuit
between the instrument and the junction of one of the secondary circuits on the

page_text: transformer with the cable, the other end of the instrument going to the junction
of the artificial line and the other secondary circuit of the transformer.
The transformer I employ is practically placed in the same points of a telegraph
circuit as is the condenser the battery and key in circuit with a primary wire both
ends of which are connected to the key or with one pole of the battery to earth
and one end of the primary coil to earth, the secondary wire being connected at
one end to the cable or line and at the other to earth.
I may sometimes find it advantageous to have an adjustable resistance or
rheostat in circuit with the primary and secondary coils of the transformer which
whilst altering the resistance in circuit with battery or line produces no inductive
effect. In certain cases also I may for purposes of adjustment when employing a
transformer in place of condensers insert an adjustable resistance or rheostat
connecting in a suitable manner its primary and secondary circuits. I may also
use the transformer in circuit with condensers and line both at its receiving and
sending ends, connected so that the primary circuit is joined to the junction of the
condenser and line, the other end being to earth, while the secondary is a closed
circuit through an adjustable resistance whereby the curbing effect is increased or
diminished at will. An adjustable resistance may also be inserted between the
primary circuit and earth.
I may also use closed magnetic circuit transformers in connection with the
artificial line in duplex working. Heretofore in order to duplex a cable it has
been necessary to have an artificial line which is usually made of a suitable
combination of resistance with capacity to imitate the distribution of resistance
and capacity in the cable to be duplexed. According to my invention I
place one or more of such transformers at the far end of the artificial
line thus obtaining the necessary balance with a considerably less amount of
capacity and at a decreased cost. This system is not intended to be used in the
duplexing of short cables. It is applicable more especially to long cables
where that which happens at the end of the artificial line has not so important
an influence on the receiving instrument as is the case when duplexing short
cables.
Dated this 3rd day of May 1894
A. F. SPOONER,
124, Chancery Lane, W.C., Agent for the Applicant.
Improvements relating to the Transmission of Signals through
Telegraph Lines and Cables.
1, JOSEPH ARTHUR LOVEL DEARLOVE, of No. 4 Great Winchester Street, iu
the City of London, Assoc. Inst. Elec. Eng. do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
My invention has for its object the improvement in the methods of working
through telegraph lines and cables and is applicable to lines aerial, submarine and
the like; it further consists in the special construction and particular employment.
in the manner hereinafter set forth of one or more "transformers'
for my
purposes.
In the annexed drawings which illustrate my invention Figures 1, 2, 3 and 4
(being end elevation, side elevation, vertical section through the line a-b, and
plan respectively) illustrate a "transformer" made in accordance with my invention
and Figures 5 to 13 are diagran s hereinafter more fully referred to.
Referring to Figures 1, 2, 3 and 4 I preferably construct my transformer, which
is of the closed magnetic circuit type, with varnished laminated soft sheet iron

page_text: stampings 61 for core and shield. The coils forming the primary and secondary
circuits are each composed of insulated copper wire of the same diameter and so
arranged or subdivided that two, three, four or more distinct and insulated circuits
are obtainable. Each coil has preferably an equal number of turns which arrange-
ment allows of the ratio of the turns in the primary and secondary circuit to be
varied within limits as is found suitable. Usually I prefer to employ a transformer
having four distinct circuits of equal turns two of which I use in series as the
primary circuit and two, also in series, as a secondary circuit as shown in Figure 2.
This construction also permits of two circuits being joined up in parallel and used
as a primary and the other two similarly joined up in parallel as a secondary. In
practically all cases for my purposes I prefer the primary and secondary when
finally arranged for working to be of equal turns. The resistance of either the
primary or secondary circuit. is ordinarily not higher than 500 ohms and they may
each have from 5,000 to 15,000 turns of wire in them. This may be determined
by the length of cable it is required to work, and the size of wire with which the
transformer is wound may be chosen to comply with the above conditions.
A transformer such as above described I use generally and for the same purposes
a, and either in combination with, or in substitution for, condensers as heretofore
employed in telegraph circuits and I will now proceed to describe the manner in
which I use such transformers to aid in the transmission and reception of signals
upon telegraph lines both for working under simplex and duplex conditions, with
devices for the adjustments necessary to good and efficient working.
Figure 5 shows the simplest form of working a telegraph line or cable on my
improved method.
In a line or cable worked under the ordinary simplex conditions I arrange my
t: ansformer P. S, battery B, key K and switch G at each end of the cable as
shown in Figure 6 with adjustable resistances R1, R2 to regulate the curbing effect
of the transformer on both "sent" and "received" signals. 1 may also place
adjustable resistances R, R' between the respective ends of the primary and
secondary circuits and earth as shewn. It may be well to explain the effect of
these resistances. Referring first to R', the current coming from the distant end
divides on arriving at the junction of the secondary circuit of the transformer P. S.
with the cable, one portion (when the switch G is standing at "receive") going
direct to the receiving instrument T and thence to earth, the other portion of the
received current going to earth through the secondary circuit S. The current
thus induced in the primary circuit P goes through the receiving instrument in the
same direction as that going through R¹. By altering the resistance in R¹ the
amount of curbing effected by the transformer can be regulated until suitable.
This allows of the same transformer being adapted to both long and short cable
circuits. The resistance R' is joined up to an insulated stop mand is only active
when the switch G is standing at "receive." This serves to connect the cable end
through R' direct to the receiving instrument T. The resistance R' is connected
in a similar manner and only comes into circuit with the key K when the switch G
is standing at "send" and by adjusting such resistance the ratio of the current
oing through the primary circuit P of the transformer to that entering the cable
direct can be varied as is found most suitable. With no resistance in R' and a
battery of negligible resistance it would be equivalent to working direct into cable.
The resistance R' constitutes means of adjusting the quantity of current from the
battery when sending into the cable through the primary circuit P. R is an
adjustment on the secondary circuit S. All these resistances are non-inductive
coils.
Figure 7 shows another mode of working wherein the battery B, by means of the
key K and switch G, is applied direct to the cable, and the receiving circuit is
If necessary &
composed of a transformer P.S. and receiving instrument T.
resistance R is inserted between the primary and secondary circuits and is adjusted
until the received signals are suitable in size and character. The use of this
resistance has already been explained when dealing with R' of Figure 6.

page_text: With simplex working on long cables on the above plan I may employ, in
combination with the arrangements shown in Figures 6 and 7, a transmitting key
which sends, immediately after each application of the battery to line and before
the line is put to earth, a curbing current of shorter duration and of opposite
sign to the signalling current, the means for effecting which are well known, and
numerous.
The curbing effect of the transformer when sending by its means given signals to
line is automatic. On the breaking of the connection between the battery and the
primary circuit of the transformer a current of opposite sign is sent to line from
the secondary circuit. But when working on short cables I prefer to apply the
battery direct to the line as shown in Figure 7 and so arrange my receiving
transformer that an efficient curb is obtained.
'
In "duplex" working I may advantageously employ transformers, placing them
for example in the various positions hereinafter mentioned.
Figure 8 shows an arrangement with a Wheatstone bridge made up of adjustable
resistances R³, R, a transformer P.S, a receiving instrument T, a line or cable C,
an artificial line A.L, a key K, and battery B. R³, R* form the arms of the bridge
to the ends of which the primary circuit of the transformer is connected at their
junctions with the cable and artificial line respectively. The receiving instrument T
is in the secondary circuit of the transformer. The resistances R³, R are of such
magnitude that they do not operate to shunt the primary circuit of the trans-
former to too great an extent, and they should be at least double its resistance.
When employing a transformer in the receiving circuit I may in some cases
insert condensers as shown at a, b, c in Figure 9. One side of the condenser a is
connected to the junction of the cable and one end of the primary circuit P of the
transformer and the other side of such condenser is connected to a low resistance
rheostat D; one side of the other coudenser with its sub-divided condenser c
arranged as shown is similarly connected to the junction of the artificial line and
the other end of the primary circuit P of the transformer; and the other side of
such condenser 6 goes to the said rheostat D whose arm is put in connection with
the battery B by any suitable key K.
Figure 1 represents another mode of working duplex with a transformer of
special winding P, S¹, S' which forms the arms of the "bridge" having one
primary and two secondary circuits each of equal turns and nearly equal resistance.
One end of the primary circuit P is connected to the battery (one pole of which
may be earthed) through a suitable key K and the other end of such primary
circuit is put to earth either direct or through an adjustable resistance R. Or the
battery may be connected. on a closed circuit with the primary P. The two
secondary circuits S¹³, S' are so connected that no effect is observable on the
receiving instrument T upon the application of the battery to the primary circuit P.
One end of the secondary circuit S is connected to the end of the cable or line
and the other end to one of the terminals of a three-terminal rheostat D whose
movable arm is in connection with earth. One end of the secondary circuit S³ is
connected to the receiving circuit and artificial line A.L. in such way that the
effect of the induced current in S' is neutralised by the induced current in S' the
result. being that no signal is produced on the receiving instrument which is thus
able to receive signals from the distant end of the system through a second trans-
former P1, S whose primary circuit is of low resistance in comparison with S.
The other end of S is connected to the rheostat D where adjustment is made for
the balancing of the effect of S' and S' upon the receiving instrument. In lieu
of the transformer P³, S³ I may sometimes substitute a condenser joined up with
the receiving instrument in one of the well-known ways.
Another mode of working duplex circuits is shown in Figure 11 the trans-
former P, P, S', S2 being constructed with two primary circuits and two secondary
circuits of approximately equal turns or of equal effect so that, when joined up as
shown and the battery applied to the cable, no signal is observed on the receiving
instrument T. The sending key K is shown placed in the bridge where the

page_text: receiving instrument is generally located. This key, which may also send
curbing currents, applies the battery direct to line. Curbing currents are only
necessary when working long cable circuits on this method. The curb given by
the key is obtained by reversing the pole of the battery after each application of
the battery to line for giving a signal its duration being shorter than that of the
signalling current though it may be of equal strength.
Figure 12 illustrates a method of joining up two or more transformers for the
receiving circuit. T', T' are independent transformers. The primary P¹ of T¹ is.
joined in series to 1 of T the end of which is put to earth either direct or
through a suitable resistance R. The secondaries S₁, S² of T', T' are joined
together in a similar manner and the receiving instrument T is placed in circuit
therewith as shown. In some cases the end of the secondary may be put to earth.
as shown at E* and a resistance R may then be connected with the primary and
secondary circuit in which the receiving instrument is placed. The resistance is
adjusted to regulate the amount of the arrival current going through the primary
circuit. When two transformers are used in the receiving circuit their respective
primary and secondary circuits may be connected in parallel but I prefer to connect.
them in series as shown.
According to my invention I cheapen the construction of the artificial line
necessary in systems of duplex telegraphy by the employment of a proportion of
transformers such as described in place of constructing such artificial line wholly of
condensers and inductive resistances.
Referring to Figure 13 I build up the artificial line A.L with a fewer number
of condensers or inductive resistances than would otherwise be necessary and.
employ transformers in conjunction with them. The diagram by way of example
shows two transformers. Their primary circuits P are connected between that
part of the artificial line which represents the conductor of the cable and earth,
the secondary circuits being closed through resistances R adjusted to suit the
requirements of the system of which they form part. I place the said trans-
formers at some distance down the artificial line always representing (say) the first
two hundred miles of cable from the "home" end by condensers and resistances or
inductive resistances in the same manner as hitherto.
Although in the diagrams I have depicted the forms of apparatus which I
believe to be best adapted for my purposes I would have it understood that I do
not limit myself thereto. In each figure I have shown an ordinary hand signalling
key but it will be obvious that other means may be employed; the points K for
example might be the levers of an automatic transmitter. Where a rheostat is.
indicated in the diagrams any suitable form of readily adjustable resistance may
be employed.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination, with a telegraphic system, of a closed magnetic trans-
former wound as described preferably having its core and shield composed of
laminated soft iron stampings substantially as and for the purposes set forth.
2. In a telegraphic system the combination of a transformer, a key or its
equivalent, and a battery, with adjustable resistances for the purpose of regulating
the curbing effect of the transformer on both "sent" and "received" signals.
3. In a telegraphic system, the combination, with a transformer, of resist-
ances R, R located between the cable and receiving instrument and cable and
battery-key respectively, substantially as and for the purposes set forth.
4. In a telegraphic system the combination, in the receiving circuit, of a
receiving instrument, a transformer, and preferably an adjustable resistance
substantially as and for the purposes set forth.
5. A telegraphic system wherein the battery is applied directly to the cable and
the receiving circuit comprises a transformer, a receiving instrument, and an

page_text: adjustable resistance inserted between the primary and secondary circuits of such
transformer.
6. In a duplex telegraphic system, the combination of a transformer and
receiving instrument in the receiving circuit with two arms of the "bridge" formed
either of adjustable resistances or of condensers and a rheostat substantially as set
forth.
7. A duplex telegraphic system comprising a transformer having a primary coil
connected between battery and earth and a plurality of secondary coils, one of
which is connected between cable and earth and another of which is connected
between earth and the receiving circuit and artificial line substantially as set forth.
8. In a duplex telegraphic system, the combination, with a cable artificial line
and rheostat, of a key placed directly between such cable and artificial line, a
transformer having two primary circuits connected respectively between the cable
and artificial line and the terminals of the rheostat the remaining terminal of which
is connected to earth, and a receiving instrument in the joined-up secondary circuits
of such transformer.
9. In the receiving circuit of a telegraphic system two or more independent
transformers having their respective coils joined in series with the receiving
instrument in the secondary circuit and preferably with an adjustable resistance
between the primary coil and the receiving circuit substantially as set forth.
10. In an artificial cable, the use, substantially as described, of transformers in
combination with condensers or inductive resistances.
Dated this 2nd day of Februar 190
A. F. SPOONER,
124, Chancery Lane, W.C., Agent for the Applicant.
A. F. SPOONER,
124, Chancery Lane, W.C., Agent for the Applicant.