US2215774A - Combined wired radio and space radio receiving system - Google Patents

Description

Sept. 24, 1940.

A. ANDREATTA COMBINED WIRED RADIO AND SPACE RADIO RECEIVING SYSTEM Filed March 8, 1939 TO RECEIVER 1 E2 i A L,-L L 1455 ///G// FE'LQUT/VCV 60/40 PEOV/DfiD W/ n Aowmmz 0/V C0660 ATTORNEY Patented Sept. 24, 1940 UNITED STATES COMBINED WIRED RADI O' AND SPACE RADIO RECEIVING SYSTEM Alfons Andreatta, Berlin-Charlottenburg, Germany, assignor to General Electric Company, a corporation of New York Application March 8, 1939, Serial No. 260;!89 In Germany August 8, 1938 4 Claims.

The invention relates to an attachment for connecting radio receiving apparatus to the line conductors of a wired radio system or alternatively to a space radiofrequency energy collecting system.

In the wired radio system, the transmissions are carried out ordinarily on several fixed carrier waves, preferably on three or four carrier waves. With such an arrangement in mind it was found that for connecting radio receivers to the broadcast wire network a number of fixedly tuned circuits can be employed which corresponds with the number of carrier waves.

The circuit according to the present invention may be arranged as explained in the following in connection with the drawing wherein the single figure discloses a preferred embodiment.

D1, D2 are the connection terminals for the broadcast wire line. When assuming that three carrier frequencies are provided for the wire broadcast, the apparatus contains three oscillating circuits L1-C1, L2C2 and L3--C3 which are tuned to these carrier frequencies, whereby C1, C2, C3 are fixed condensers. The coils L1, L2, L3 are preferably higlnfrequency iron coils whose self inductance can be set for the desired value by moving the iron core.

The three oscillating circuits are coupled to the broadcast wire network across the coils S1 to S6 whereby the coils S1 to S6 are placed in series such that each oscillatory circuit is coupled always across two respective coils which are symmetrical to the wire net and to the ground point of the coil circuit. The coils L1, L2, L3 of the oscillating circuits have tappings 131,132 and B3 which are connected to a switch U1. The switch U1 is'grounded across a potentiometer P whose tapping is connected across a switch U2 to the input E1 of the radio receiver. The switch U1 affords the selective connection of one of the three oscillating circuits L1-C1, L2C2 and L3Cs with the input terminal 121-122 to the receiver. The switch U2 affords switching to broadcast reception by means of the antenna A.

The circuit shown inside the rectangle drawn in dash lines may serve with equal advantage as input circuit for wire broadcast receivers, or for the connection of measuring instruments or control apparatus to the broadcast wire net.

The advantages of the circuit arrangement according to the present invention are seen to consist in particular of the following: With the stated arrangement of the oscillatory circuits L1--C1, L2C2 and Ls--C3 it is accomplished that when connecting or utilizing one circuit the other .core which can be moved by screw means. in

In constructing the coils L1 to L3 as highfrequency iron coils it is easy to set the oscillatory circuits for the desired carrier frequency.

Owing to the symmetrical coupling of the oscillating circuits to the broadcast wire net, the center of the coil arrangement S1 to S6 may be grounded as shown in the drawing so that disturbances appearing symmetrically on the two broadcastwires D1 and D2 can be suppressed to a great extent.

This coil arrangement has the further advantage that it is possible to obtain a favorable matching or an excessive matching of the apparatus with the broadcast wire net without the necessity of using special preliminary coils which 2: as such would represent a loss in energy.

The setting of the attached apparatus for the various wire broadcast waves is done simply by setting the switch U1 which may, if desired, be designed as a press bar. 3

The advantage of this arrangement over attachment apparatus in which the tuning to the individual carrier waves is accomplished by moving a variable condenser, resides in that at a change of the frequency of one of the broadcast 35 waves no changes need be carried out at the switching organ, and the attachment apparatus can be adapted for the changed wave simply by a subsequent setting of the respective coil of the oscillatory circuit. 40

The attachment device according to the invention distinguishes itself by the fact that owing to the absence of a variable condenser it requires comparatively little space.

A further advantage on account of the absence of a variable condenser is seen in that the tuning of the apparatus can be rendered independent of temperature influences to a wide degree, because the fixed condensers C1, C2, C3 can be rendered greatly independent of the temperature without difficulties for instance by suitable choice of the dielectric, and the iron core coils to be employed can likewise be rendered insensitive to the temperature to a wide degree.

Since for each individual broadcast wire wave 55 a special oscillating circuit is employed the possibility exists to compensate differences of the level potential of the various broadcast wire waves by measures taken at the individual oscillatory circuits, for instance the damping and/or the coupling degree may be varied, or the respective tapping B may be moved so that all frequencies to be received the input potential at the terminals E1, E2 has the same amplitude.

The use of a respective oscillating circuit for each wave to be received in connection with the switch U1 offers the further possibility of blocking the reception of a wave in that the switch U1 is provided with a blocking means preventing the connecting of one of the oscillating circuits. This condition can be utilized if certain parties or groups of parties is to be given the opportunity to receive these respective waves.

I claim:

1. A radio receiving system comprising wire line conductors for conveying carrier frequency energy, a plurality of oscillation circuits each resonant to a different carrier frequency coupled to said conductors, low potential points of said circuits being connected together and to ground, high potential points of said circuits each connected to a terminal switch contact, a switch contact arm cooperatively related to said contacts,

a load impedance connected between the contact arm and ground, said contact arm adapted to selectively connect the load impedance to one of the oscillation circuits, a connection from the load impedance to a terminal contact, a space radio frequency energy collecting system connected to an additional contact, a receiver of carrier frequency energy, and a switch contact arm adapted to selectively connect said receiver to one or the other of the two last mentioned terminal contacts.

2. A radio receiving system according to the invention defined in claim 1 wherein the oscillation circuits each comprise a high frequency coil provided with an adjustable iron core and a shunt fixed condenser.

3. A radio receiving system comprising a balanced transmission line for conveying carrier frequency energy, an equal number of coils serially connected between each line and ground, an equal number of oscillation circuits each resonant to a different carrier frequency coupled to a pair of said line coils which are symmetrically disposed with respect to ground, low potential points of said circuits being connected together and to ground, high potential points of said circuits each connected to a terminal switch contact, a switch contact arm cooperatively related to said contacts, a load impedance connected between the contact arm and ground, said contact arm adapted to selectively connect the load impedance to one of the oscillation circuits, a connection from the load impedance to a terminal contact, a space radio frequency energy collecting system connected to an additional contact, a receiver of carrier frequency energy, and a switch contact arm adapted to selectively connect said receiver to one or the other of the two last mentioned terminal contacts.

4. A radio receiving system comprising a balanced transmission line for conveying carrier frequency energy, an equal number of coils serially connected between each line and ground, an equal number of oscillation circuits each resonant to a different carrier frequency coupled to a pair of said coils which are symmetrically disposed with respect to ground, low potential points of said circuits being connected together and to ground, intermediate points on the inductances of said circuits each connected to a terminal switch contact, a switch contact arm cooperatively related to said contacts, a potentiometer resistance connected between the contact arm

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