US1093240A - Wireless-telegraph receiver. - Google Patents

Description

J. G. BALSILLIE.

WIRELESS TELEGRAPH RECEIVER.

APPLICATION FILED Immo, 1914.

Patented A111214, 1914.

` UNITED sTATEs PATENT OFFICE.

JOHN GRoEME BALsILLIE, or MELBOURNE, VICTORIA, AUSTRALIA.

WIRELESS-TELEGRAPH RECEIVER.

.t-ain new and useful Improvements in l/Vireless-Telegraph Receivers, of which the following is a specification.

My invention relates to wireless telegraph receivers associated with an air wire or ab sorbing circuit of the .looped type.

My invention is usable in either of two forms, the one for receiving in one certain oscillation frequency and the other for receiving in either of two oscillation frequencies or in two oscillation frequencies simultaneously. In the latter form the receiver is used in connection with two-tone transmitters in which'the dots are transmitted in one oscillation frequency and the dashes in another distinct oscillation frequency. The circuits differ from each other in that in the one case one leg of the circuit. is operatively idle, the values contained in it being how-' ever variable by adjustment of a variometer l'eactance and a variable condenser' included in series in it. In -the other case both legs 0f the absorbing circuit are operative and they each include a variometer reactance and a. variable condenser. Oscillation circuits in shunt around these variable condensers are inductively coupled to a quantity detector circuit containing a telephone` which lat-ter circuit is tuned to the group frequency and not to the oscillation frequency of the received waves. The shunt oscillation circuits which are so coupled to the detector circuit are connected to the legs of the absorbing circuits around the variable condensers therein, and they each include as well -as their respective variable coupling condensers another variable condenser and a Variable inductance, which latter forms the primary of the inductive coupling with the detector circuit before mentioned. In each shunt oscillation circuit the coupling condenser and the ,variable condenser insald circuit are assoin which the intermediate movable plate is connected to the upper part of the absorbing circuit and the outer plates to the shunt containing the variable inductance and to the Specilcation of Letters Patent. Patented Apr, 14, 1914, Application filed February 10, 1914. Serial No. 817,762.

foot of the absorbing circuit respectively. The reactance variometers used may be variometers of the Lorenz type consisting of two coils, one pivotallyv mounted within the other and adapted to be turned on its axis, said coils being connected in series, whereby when they are in'plane with each other the circuit contains minimum reactance, which is variable up to a predetermined maximum by altering their angulairelations up to a maximum which is attained when the axes of the coils are located at right angles. But the same purpose may be effected by otherwise constructing these reactance variometers according to any known method, whereby immediate -variation in the reactance in the circuit in which they are contained may be secured by the relative movement of one part of the variometer structure to another part thereof.. The detector circuit is 'tuned to oscillate in the group frequency of the received 'train4 of waves by varying the condenser which is in parallel with the telephone connected in said circuit..

Referring to the annexed dra-wings: Figure l is a 'diagrammatic view of the essential parts of la. receiver circuit according to my invent-ion, adapted for the reception of waves in one certain oscillation frcquency. Fig. 2 is a similar diagrammatic view showing the circuits arranged for the reception of messages in either one or other of two dii'iierent oscillation frequencies, or for the reception of a two-tone message in which the dotsare transmitted by means of waves having one certain oscillation frequency andthe dashes by waves having a different oscillation frequency. Fig. 3 is a diagrammatic view showing the coupled condenser connections as used in the receiving 'shunt circuits,-in either arrangement FiU. 1

or'Fig. 2. p l

In Fig. l' the'absorbing circuit A which must necessarily be of the looped type, is shown as a looped air wire of which the leg a is idle and the leg `t1 is connected to the receiver shunt circuit. The leg a contains in series a reactance variomcter X and a variable condenser Y. A

B and B1 are connections to earth or a suitable capacity. Inasmuch as the earth, in this connectiomoperates by virtue ot' its great capacity, I have employed the .arm master-capacity toexpress this condition.

meaning thereby, either theiearth or such other capacity as shall be suitable to the purpose in view.

On the operative side al of the circuit A is. a variable condenser C. A shunt circuit -including a variable condenser D and a The condenser-s C and D inthe vshuntcircuit are constructed preferably in the manner shown in Flg. 3 but may be otherwlse mechanically coupled so that they may bey moved only together in equal amount. Any movement of one of these condensers.' therefore effects the movement -of the other one and the. shunt circuit is thus maintained in resonance with the circuit A when any adj ustment is mada The inductances E and G are in practice madeV as the primary and secondary circuits of an air core transformer..

ln the case 4of the receiver shown in Fig. 2 a shunt circuit is used on either leg of the absorbing loop, said shunt circuit being connected electrostatically to said legs respectively on either side of the variable conde-nsers C. and Y. Above these shunt connections reactance variometers X and Z are inserted in the circuit. The telephone circuit is as in the previous. case tuned to the group frequency of the received wave'train while the shunt circuits are in resonance with the absorbing loop and therefore osclllate in =the oscillation frequency of the received train of Waves. The condenscrs in the shunt circuits are connected together' in the salue manner as the eondensers C and D, Fig. 1,and the inductances Eand E1 arevariable and form primaries of an air core transformer' of which the secondary G is included inthe telephone circuit. This air core transformer-'is constructed so that either of the primaries E or El may be'rendered inactive in relation "to the detector circuit when it'is required to `prevent reception of wavessin the certain oscillation .frequency to which that circuit containing it is tuned. The telephone in that case is receptive only to signals received through the other shunt circuit, but where both primary inductances E- and E1 are maintained in active relation 'to the transformer secondary G, the telephoneK will respond to .waves having the same group frequency but having distinct oscillation frcquencies corresponding respectively with the adjustment of the circuits on either leg of Athe absorbing loop. In the latter case two l tone messages are readily receivable in the E telephone, one of the shunt circuits being tuned to the oscillation frequency of one of the wave trains and the other shunt circuit to the oscillation frequency of the other of them. Similarly when listening in, the operator may detect signals passingA in either of two oscillation frequencies and if he desire to` receive either of those signals he can by dissociating the primary carrying the other of them, concentrate his attention on the required signals which have their own distinct oscillation frequency. The detector used must be a quantity detector, preferably of the known crystal contact form.

.lt is obvious that the feet B B1 of the absorbing circuit A which are connected to earth or a suitable capacity may also be con'- nected together. It is not material whether the variometers X and Z be located above or below the oscillation shunts. The connected circuits whether arranged as in Fig. l or Fig. 2 oscillate as a whole, that is to say'the currents in the oscillation shunts swing rhythmically with the currents inthe absorbingr circuit, and the variometers X and Z and the inductances E and El and the condensers C and D and-W and Y must be adjusted until the respectivevalues on either side of the loop circuit A are balanced so that the oscillation shunts oscillate freely at the rate of oscillation frequency of incoming waves. Facility for tuning out is thuspreadily secured. The detector circuit is responsive to any oscillation frequency in either shunt through the medium of the inductive coupling, but lit swings in its own ytime period which is determined by the adjustment of the condenser J at a rate which corresponds to the group frequency and not to the oscillation frequency of the received waves.

particular oscillation frequency, for any particular receiver may be tuned to receive from any particulartransmitter working on the two-tone principle and emitting two distinct wave trains of different frequencies pertaining respectively to dots and dashes but having a certain predetermined group t frequency. Reading of the message is therefore possible only When the detector circuit is tuned to the predetermined arbitrary group frequency and either side of the absorbing circuit (Fig. 2) is also tuned respectively to the' oscillation frequencies pertaining to the dots and dashes constituting the signals.

What I claim as my invention and desire to secure by Letters Patent is 1. A wireless telegraph receiver comprising a' looped absorbing circuit the legs of which are connected to a master capacity, one of-said legs containing a reactance vari- 'ometer and a variable condenser and the other of said legs containing a variable con- Not merely is it possible to tune for one denser, an oscillation circuit shunted around said last mentioned condenser and containing a variable condenser and an inductance, and a detector, circuit inductively coupled to said oscillation shunt and including a telephone receiver, a variable condenser in parallel With said receiver,and a quantity detector in series with said last named condenser.

2. .A wireless telegraph receiver comprising a looped absorbing circuit having legs, both of which are connected to a master capacity, one leg including a variometer reactance and a variable condenser, the other leg including a variable condenser and a shunt circuit connected around said condenser, said shunt circuit itself including a variable condenser and a variable inductance which forms the primary of a coupling transformer and by means of which said shunt circuit can be tuned to the oscillation frequency of the received waves, and a detector circuit cooperating with said shunt circuit and including an inductance vhich forms the secondaryof said transformer, a quant-ity detector, a variable condenser, and a telephone receiver', said last named condenserl and said telephone receiver being connected in parallel.

3. In a Wireless telegraph receiver', in combination, a looped absorbing circuit having both of its legs'connected to the earth, each of said legs including a variable condenser, one of said condensers being connected in parallel with a shunt circuit and the other of said condensers being connected in series with a variometer reactance, said shunt circuit including a variable condenser and a variable inductance connected in series, said inductance forming the primary of a coupling transformer; and a detector circuit cooperating With said shunt circuit and including` an inductance which forms thesecondary of said transformer, a quantity detector arranged in series With saidinductance, and a variable condenser connected in series with said quantity detector, there boing a telephone earpiece -shunted around said last named condenser.

u4. In a Wireless telegraph receiver the combination with a looped absorbing circuit having legs, both of which are connected .to a master capacity, each of said legs including a variable condenser and at least one of said legs having therein a reactance varicircuits comprising an additional variable condenser in circuit with a variable inductance, which inductance forms the primary of a coupling transformer; together with a detector circuit which includes an. inductance common to both of said variable in? ductances and forming the secondary of a transformer which is adapted to be energized by either of said prlmaries, said detector circuit also including a quantity detector and a variable condenser in series with said secondary; and a telephone earpiece in parallel with said last named variable condenser.

5. A Wireless telegraph receivercomprising, in combination, a looped absorbing circuit having two legs both of Which are grounded, a varioineter reactance in each of said legs, a variable condenser in each leg and arranged in series with the corresponding variometer reactance, a shunt circuit connected around each of said condensers, each of said shunt circuits itself containing a variable condenser arranged in series with a variable inductance, each of said variable inductances forming the primary of an air core transformer; together with a detector circuit comprising an inductance which forms the secondary of said transformer and is arranged to coperate with either or both of said primaries, means for detecting the existence of Waves in said detector circuit, and means for tuning said detector circuit.

6. In a Wireless telegraph receiver, a looped absorbing circuit having legs, a shunt yoscillation circuit connected Witheach of v tance in each of said oscillation shunts, each of saidvariablel inductances forming the primary of an air-core coupling transformer, and a detector circuit containlng an inductance, a quantity detector, a variable condenser, and a telephone earpiece, vsaid last named inductance forming the secondary of said transformer and said variable capacity being in parallel with said telephone earpiece.

In testimony whereof I aiiiX my signature in presence of two witnesses.

L JOHN GROEMErBALSILLIE Vitnesses:

. CHARLES I-IAa'rm'rr,

LUCY GREEN.

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