US2265203A

US2265203A - Telephony

Info

Publication number: US2265203A
Application number: US270244A
Authority: US
Inventors: Six Willem
Original assignee: Hartford National Bank and Trust Co
Current assignee: Hartford National Bank and Trust Co
Priority date: 1938-05-16
Filing date: 1939-04-26
Publication date: 1941-12-09
Anticipated expiration: 1958-12-09
Also published as: FR854758A; GB525676A; BE434364A

Description

Dec. 9, 1941. w. SIX 2,265,203

TELEPHONY Filed April 26, 1959 BIA/EM ro/r 14 6212c Patented Dec. 9, 1941 UNITED STATES PATENT OFFICE 2,265,203 rausrnomr Willem Six, Eindhoven, Netherlands, assignor, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as

My invention relates to telephony systems and more particularly to signal receivers for such systems. I

My invention is particularly concerned with signal receivers for receiving signalling currents which are transmitted directly or by carrier waves over a conductor which may also be used for speech transmission, and which currents have a frequency located in or adjacent to the frequency range of the speech currents or the speech sideband.

As is well known, signal receivers of the above type must be such that the signal circuit cannot be erroneously energized by speech currents of a frequency which is the same as or close to the frequency of the signal currents.

The main object of my invention is to provide a signal receiver with which the signal circu't can be energized only by the signal currents.

A further object is to provide a signal receiver which is simple in construction and reliable in operation.

Further objects and advantages will appear as the description progresses.

In accordance with the invention I control the signal circuit by two relays or relay combinations of which one sets the signal circuit into operation with a time-lag and the other sets the signal circuit into operation without a time-lag, and make the time-lag of such duration that the signal circuit will not be established by current pulses caused by speech currents of a frequency close to or equal to the signal current frequency.

In order that the invention may be clearly understood and readily carried into effect, I shall describe the same in more detail with reference to the accompanying drawing in which Figure I is a schematic diagram of a signal receiver according to one embodiment of the invention, and

Figure II is a schematic diagram of a signal receiver according to another embodiment of the invention.

The signal receiver shown in Figure I comprises a transformer 3 having a Primary winding 9 whose terminals I and 2 are adapted to be connected to a telephony transmission line (not shown) transmitting both low-frequency signal currents and speech currents. If the signal currents are transmitted by carrier wave over a conductor, the terminals I and 2 would be connected to the output circuit of a demodulator which demodulates both the modulated signal currents and the speech currents received. Thus, in any case both low-frequency signal currents and speech currents are supplied to terminals I and 2.

Transformer 3 has a secondary winding ii tuned to the signal frequency by a condenser l, and having one end connected through a conductor H to the grid of a triode 5, which is connected as an anode rectifier, and having its other end connected through a biasing battery I! to the cathode of tube 5.

The receiver also comprises two relays l3 and II having normally-open armatures l5 and I6 respectively connected in series in a signal circuit 6. Armature i5 acts instantaneously, whereas armature i6 acts with a predetermined time delay both in opening and closing. As time-delay relays of this type are well known in the art further description of the same is believed. unnecessary.

The coils of relays i3 and H are connected in parallel in the plate circuit of tube 5 and for this purpose one end of each coil is connected through a conductor I! to the plate of tube 5, and the other ends of the coils are connected together and through a battery I and a conductor l8 to the cathode of tube 5, a condenser 8 connected across the plate and cathode of tube 5 serve to smooth the rectified plate current.

In operation of the receiver, the signal currents received at terminals I and 2 produce a rectified voltage across the coils of both relays l3 and H. Relay I3 is energized and armature i5 closes its contact practically instantaneously but relay I 4 becomes energized and armature it closes its contact only after a predetermined time interval. Thus, the signal circuit 8 is established only at a predetermined time after voltage is applied to the coils of relays i3 and I.

When the speech currents received containcomponents whose frequencies are located adjacent the signal frequency and produce a voltage at the grid of tube 5 for a short time, the rectified voltage applied across the coils of relays I 3 and H causes armature l5 to close immediately whereas armature l6 remains open for a short time period. As those components of the speech currents whose frequencies are located adjacent the signal frequency occur for only a short time interval, armature It will not be closed by such currents, provided, of course, the time-lag in relay I4 is made longer than the duration of such currents. In practice, the relay it may have a timelag of about second. When signal currents consisting of successive impulses are received the relay l3 opens and closes its armature ii in the rhythm of these impulses, the armature II of the relay It remains, however, closed due to the timelag of about lit-V10 second which is longer than the duration of each interval between two successive signal impulses. By the closing and opening of the armature I! of relay It the signal impulses are transmitted in the signal circuit 8.

The receiver shown in Figur 2 is similar in many respects to that of Figure l and the same reference numerals are used to designate the same parts. However, in Figure 2 the relay ll of Figure 1, which relay is energized and de-energized with a time-lag, is replaced by two relays 2. and 22 having normally-closed armatures 2| and 23 respectively, both of the latter relays being energized quickly but de-energized with a time-lag. The coil of relay 20 is connected in parallel with the coil of relay l3, whereas armature' 2! controls a circuit comprising the coil of relay 22 and a battery 24. Armature 23 is connected in series with-armature IS in the signal circuit 8.

When signal currents are received at terminals I and 2, rectified voltage is applied across the coils of relays l5 and 20 with the result that the armature I5 closes immediately and armature 2| immediately opens and causes deenergization of relay 2!. After a suitable time interval armature 23 closes to thereby establish the signal circuit 6.

It the signal currents are constituted by a number of periodical pulses, armature l5 of relay l3 will open and close periodically so that these pulses are transmitted in the signal circuit 6. Although the energization of relay 20 is periodically interrupted by these pulses, this relay is deenergized with a time-lag, and thus the armature 2| will remain open, relay 22 will remain deenergized and armature 23 will remain closed.

When receiving speech-current components of short duration armature 2| is also opened, but due to the fact thatrelay 22 is de-energized with a time-lag, armature 23 is prevented from closin and thus the signal circuit 6 will not be erroneously established by these speech currents.

The signal receiver as shown in Fig. 2 has the advantage over that shown in Fig. 1, that the relay combination 20 and 22 contains relays which are only de-energized with a time-lag i. e. have v a time delay in only one direction. Such relays are more readily constructed than a relay such as the relay Id of Figure 1 which has to be energized as well as de-energized with a time-lag.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and discussed or to the use of time relays of any particular type, because obvious modifications will occur to a person skilled in the art.

What I claim is: v

l. In a telephony system in which signal currents of a frequency at least close to the frequency range of the speech-currents or the speech side-band are transmitted over a conductor adapted to serve also for speech transmission, a local signal circuit, a signal receiver controlling said local signal circuit and comprising electroresponsive means including a contact connected in said circuit and adapted to close and open without time delays, second electro-responsive means including a contact connected in said circuit and adapted to close and open with predeterminedtime delays, and means to simultaneously energize both said means with a voltage produced by the signal currents and speech currents oi similar frequency.

2., In a telephony system in which signal currents of a frequency at least close to the frequency range of the speech-currents or the speech side-band are transmitted over a conductor adapted to serve also for speech transmission, a local signal circuit, a signal receiver controlling said local signal circuit and comprising an electro-magnetic relay having a contact connected in said circuit and adapted to close and open without a time delay, a second electromagnetic relay having a contact connected in said circuit and adapted to close and open with predetermined time delays, and means to simultaneously energize both relays with voltage pulses produced by the signal currents and speech currents of similar frequency,

3. In a telephony system in which signal currents of a frequency at least close to the frequency range of the speech-currents or the speech side-band are transmitted over a conductor adapted to serve also for-speech transmission, a local signal circuit, a signal receiver controlling said local signal circuit and comprising an electrical relay having a contact connected in said circuit and adapted to close and open without a time delay, a second electrical relay having a normally-closed contact adapted to open with a time delay, a circuit including said latter contact and a voltage supply, a third electrical relay having a coil in said latter circuit and a normallyopen contact in said signal circuit and adapted to open with a time delay, and means to simultaneously energize the first two relays with voltage pulses produced by the signal currents and speech currents of similar frequency.

4. In a telephony system in which signal currents of a frequency at least close to the frequency range of the speech-currents or the speech side-band are transmitted over a conductor adapted .to serve also for speech transmission, a local signal circuit, a signal receiver controlling said local signal circuit and comprising an electrical relay having a normally-open contact connected in said circuit and adapted to close and open without a time delay, a second electrical relay having a normally-open contact connected in said circuit and adapted to both close and open with predetermined time delays, and means to simultaneously energize both said relays with a voltage produced by the signal currents and by speech currents of similar frequency.

WILLEM SIX.