US2476313A - Control system - Google Patents

Description

july 19, 1949. J. s. MAIDLOW, JR., ET AL 2,475,313

CONTROL SYS TEM Filed Oct. 16, 1943 '2 Sheets-Sheet 1 July 19, 1949.

Filed Oct. 16, 1943 J. S. MAIDLOW, JR., ET AL.

CONTROL SYSTEM 2 'sheets-sheet 2 3 2 Tsen/Mw.

/0 Mrs fname Patented July 19, 1949 CONTROL SYSTEM John S. Maidlow, Jr., and James M. Reynolds, United States Army Application October 16, 1943, Serial No. 506,564)

In Australia February 25, 1943 5 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to radio communication, and more particularly to improvements in radio telegraph systems employing means for automatically transmitting signals and automa-tin cally recording signals in print at va receiving station.

Radio signals as generally received are too feeble to actuate a relay, unassisted, for the purpese of controlling a telegraph printing device of the class known as Teletype. This inadequacy of the radio signal for the desired purpose is also aggravated by the radio phenomena known as fading and climatic conditions, which may, if occurring during the signalling period, cause loss of an impulse and the mutilation of the transmission code.

It is, therefore, an object of this invention to provide a novel electrical circuit and arrangeof elements whereby a received radio signal is suiciently amplified to actuate a relay contrcliing a telegraph printing device.

A further object of the invention is the provision of a radio telegraph system in which the operation of a recording printer at a receiving station automatically causes a radio transmitter, which is already in operation at the receiving station, to retransmit the signal to the original transmitting station Where the signal is received and a printed record made thereof, thus insuring the receipt of the message by the original receiving station.

These and other objects are attained by the novel circuit and arrangement hereinafter described and illustrated in the accompanying drawings, forming a part hereof, and in which:

Figure l is a schematic diagram of an electrical circuit embodied in the invention.

Figure 2 is a diagram of communication system according to the invention.

Referring to the diagram, a diversity radio reception system is shown to include three radio receiving sets I, 2, 3, adapted to receive interrupted continuous wave signals. The antennas of the receiving sets are spaced by ten Wave lengths from each other. The audio output of each receiver is separately rectified by rectifying (Granted under the act amended April 30, 1928; 370 O. G. 757) l, thereby of March 3, 1883, as

tubes 4, 5, respectively, producing a combined negatively directed voltage which is passed through a filter to allow only the modulated frerduency of the tone transmitted to pass.

The voltage from the iilter is applied to the grid 8 of a direct current amplifying tube l, the cathode 9 of which is returned to ground through the plate circuit il of a vacuum tube Iii of the beam power type.

The output of tube l' is appplied directly to the grid I3 of another vacuum tube Iii, preferably of the beam power type. Normally with no signal input to the receivers, no negative voltage is applied to the grid of the direct current amplifier' l. This allows current to ow in the amplifier tube l. This current flow places a high bias on tube I 4, keeping the current in the plate circuit of tube I4 extremely low.

When the incoming signal has the proper modulation frequency, negative bias is placed on the grid 8 of tube l', causing the tube to draw less current, which lowers the bias voltage on the grid of tube I, causing current to ow through the plate circuit of tube I 4.

The plate current change in the direct current amplifier tube 'l is maintained at a very low value up to a predetermined value of negative grid voltage by the vacuum tube I0, which has its plate II connected to the cathode 9 of tube l. The voltage of tube l) is stabilized by the assistg ance of a glow type voltage regulator tube l5. A negative grid voltage slightly above the predetetrmined negative grid voltage mentioned above causes a large change in the plate current of tube resulting in a great change in the bias of the tube l ffl. This being a positive change causes tube l to draw a large current, A sensitive relay is placed in the plate circuit of tube I4.

In operation the gain of the receivers is adr justed so that the voltage produced by the noise level is below the critical point of the grid of tube 7. If the incoming modulated continuous wave is above noise level it will cause the voltage on the grid of the amplifier tube 7 to rise above the critical point.

In practice, a rIeletype transmitter and receiver is used at each station. Two transmitting irequencies are used, one for transmitting an original message, and the other for retransmitting a received message back to the original transmitting station. The incoming signal is received by one or more of the radio receivers, from which it is rectified, filtered and passed to the amplier tube 'I, to produce a current in the plate circuit thereof. A small current in tube 'I will cause a low bias of tube I4, and consequently cause the ow of a large current in. the plate circuit of tube I4. This large current is of suicient strength to actuate relay 50 which controls a Teletype apparatus I'Il for receiving' and printing a message. When one station is receiving its radio transmitter is placed on the air by closing contacts I9, to send out tone modulated signals. The transmitter is then keyed by the Teletype contacts in accordance with the standard Teletype five unit permutation code to cause the received message to be retransmitted by the transmitter I8 back to the original transmitting station where itis received and a printed record made thereof by the Teletype apparatus at the original transmitting station.

Thus, when message is transmitted by a iirst station to a second station, it is received by thev second station and retransmitted back to the rst station, where it is received and a printed record made thereof. The rst station then knows d'eiinitely that the message has been received by the second station.

Should at any time the receiving station desire to interrupt. the transmitting station, the radio transmittingkeying circuit is opened by a manual switch, causing the Teletype machines at both stations to run open.

.To insure minimum of static interference, either the transmitting or receiving antennas, or both,` are of the V-beam type.

-The invention having been described, what is claimed is:

1. In a control system, a source of direct current electromotive force; an actuating circuit; a triode including an anode, a cathode and a control grid; means connecting said grid and cathode to said actuating circuit and said anode and cathode across. said source to place positive potential at said. anode; said means including means responsive to the current fed to said cathode to greatly reduce said current upon a predetermined drop'thereof and to greatly increase the same upon a predetermined rise thereof from'its said reduced magnitude; a tube having a cathode, a controlgrid and an anode; wires connecting the last-named grid to the negative pole of saidV source and the last-named cathode tothe first-named cathode; a circuit passing through said last-recited anode and cathode, said circuit including a source of direct current electromotive force therein; and means to be energized and deenergized in said last-named circuit.

2. A control system denned in claim 1 in which said'rst-named means comprises a tube having anv anode connected to the cathode of said triode, a screen grid, and a cathode connected to said actuating ycircuit as well as to the negative pole of the first-named source of said claim l; and means for supplying a constant high voltage positive potential at said screen grid with respect to thelast-mentioned cathode whereby the plate current change in the first-named tube of claim 1 is maintained at a very low value up to a predetermined value of negative grid voltage and a change beyond said predetermined value effects prompt great` change in the current.

3. In a control system; a triode having an anode, a control grid and a cathode; a second tube=having an anodeconnected to said cathand cathode of said driven tube, a source oi power, and means to be energized.

fi. In a control system the combination with a circuitincluding therein means to be controlled of an' actuating circuit; a triode including an anode, .a cathode. and a control grid; said grid and cathode being connected across said actuating circuit; a single tube for controlling pulses to `the first-named circuit, including an anode and a cathode. connected in said first-named circuit, and a control` grid; a second circuit including the series current path of the first-named anode, the first-named cathode,l the second-named cathode andthe last-named grid, said series current path including a source fofpolarizedelectricity therein connected to affect the last-named grid negatively; whereby the last-named tube will be increased and decreased in conductivity inversely as. the said .triodey said'rst-named circuit includingftherein avsourceA of power affecting the second-named anode positively; and means for increasing the degree of sharpness of said triode in becoming. `conducting and non-conducting in response toV changes in the potential across said actuating circuit, the last-named means comprising means in the cathode circuit of said triode that saturates whenthe triode is not biased by said actuating. vcircuit.

5( In a control system, the combination with a circuit including` 'therein means to be controlled of .an actuatingl circuit; a. triode including an anode, a cathode and a control grid; said grid and cathode being connected across said actuating, circuit;` a single tube for. 'controlling pulses to the first-.named circuit, including an anode and a cathode connected in said first-named circuit, and a control. grid; a second circuit including thev series current path of vthe first-named anode, the Yirst-named cathode, the secondnamed cathode and thelast-named grid, said series current path including. a source oi polarized electricity 4therein connected to aifect the last-named grid negatively; whereby the lastnamedV tube will' be increased and decreased in conductivity inversely as the said triode; said rst-na'med circuit including therein a source oi power aiecting the second-named anode positively; and means for increasing the degree of sharpness offsaid' triode in becoming conducting and non-conducting in response to changes in therpotenti'al across said actuating circuit, the last-named means comprising a tube having an anode connected to the cathode of said triode and a cathode connected to the said actuating circuit, said last-named tube including means whereby it is saturated bythe' current of said triode when the latter is not actuated by said actuating circuit;

JAMES M. REYNOLDS.

JOHN S. MAIDLOW, JR.

(References on. following page) 5 REFERENCES CITED UNITED STATES PATENTS Number Name Date Read Jan. 17, 1922 Turner July 4, 1922 Heising Aug. 21, 1923 Bennett Sept. 16, 1924 Beverage et al. Aug. 30, 1932 Griflth Aug. 22, 1933 Kaliman Dec. 25, 1934 Watson June 4, 1935 Robinson June 21, 1938 Number 6 Name Date Spencer et al Jan. 3, 1939 White Aug. 13, 1940 Thompson May 13, 1941 Buckingham May 5, 1942 Boughtwood July 28, 1942 Brubaker Mar. 9, 1943 OTHER REFERENCES Radio Engineering Handbook by K. Henney, published by McGraw-Hill Book Co., New York city, third edition, copyright 1941, page 582.

Radio Engineers Handbook by F. E. Terman, published by McGraw-H111 Book Co., New York city, rst edition, copyright 1943, page 660.

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