US2447392A

US2447392A - System for aligning receiver and transmitter circuits

Info

Publication number: US2447392A
Application number: US595353A
Authority: US
Inventors: John F Byrne
Original assignee: US SEC WAR
Current assignee: United States, WAR, Secretary of; US SEC WAR
Priority date: 1945-05-23
Filing date: 1945-05-23
Publication date: 1948-08-17
Anticipated expiration: 1965-08-17

Description

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.N 4 NN IN1/Ewan JOHN P BYRNE ATT ORNEY Patented Aug. 17, 1948 SYSTEM Fon ALIGNINGjRECEIvnR AND l l''IBANsMrrfrER craculfr's A1,011 F ,Byrne,-Wel1esley Hills, .Mass., assignOl. ,t0

I .the United saresti Amer-ica as represented by I z the Secretary f WM' v I I* t Application May 23, 1945, SerialNo. '1595,'353" 1 claim. (orario- 113) The present invention relates in general to ceiverand a transmitter, thefoutput frequencylof which is determined by a variable frequency Aoscillator which is common to.both receiver and transmitter. The .use of a common oscillator to determine the output frequency of the transmitter makes it certain under `all conditions that the frquency of the transmitter is the same as that to which the receiver is tuned; that is, the incoming signal frequency One of the advantages of the present invention is that an operator receiving signals on the receiver may transmit a signal back to the sender merely by turning on the power circuits of the transmitter without any further adjustment, since the common oscillator permits the simultaneous tuning of the receiver and transmitter to a single frequency.

The range of frequencies that can be covered by a receiver or transmitter having single tuning circuits in which a desirable sensitivity in the case of a receiver, and effective transmitting range in the case of a transmitter are maintained, is limited by practical considerations in the design of their circuits. Accordingly, in the present invention when it is desired to cover a broad range of frequencies, there are provided separate tank circuits for several bands of frequencies within the entire range covered. The common oscillator is designed to be tunable over a band greater than the width of the band covered by the individual tank circuits.

Other objects, features and advantages of this invention will suggest themselves to those skilled in the art and will become apparent from the following description of the invention taken in connection with the accompanying drawing which is a block diagram showing the preferred embodirnent of the invention.

Incoming signals are received on the receiving antenna, lil and passed through one of the receiver tank circuits II which has been chosen by the operator as the tank circuit proper to cover the band of frequencies in which the received signal is found. The selection of the proper tank circeived signal is found. The selection of the proper tank circuit is made by switches I2 and I3. The signal then passes into the mixer section I4 of the receiver Where it is combined with oscillations produced by thetunable oscillator I5, resulting in an intermediate frequency which in the remaining parts IB of the receiver is amplified and detected.. inY anconvlentional manner.. @.{I'heA oscil- .later el 5. istunab1efmar1ual1y over a bander frequencies-whichqis greater in width than the band of ffrequenciesacovered by fthe tank .circuits A ,B, C, vandfD,q;gener,ally designated as II.

Itis contemplated;wandering-the creratlfof the receiver all of the circ of ,thetransrnitter will .be energized with-the lpossibl-e "exception of the final.powerzconsuminsylead.-Ci ts Sechi-as the antenna and tan-k circuits. e, ,the .switch Il open n-o oscillations are lfed into the transmitter from the oscillator; therefore, no energy can be radiated from the transmitter antenna 2U. However, all the circuits of the transmitter are tuned and put into condition so that when the switch Il is closed the transmitter will transmit a wave of the same frequency as that to which the receiver is tuned. This is accomplished as follows: The frequency to which the transmitter in termediate frequency circuits 2l are tuned is the same as that to which the receiver intermediate frequency amplifier circuits are tuned. The result is that when oscillations from this amplifier 2! are mixed with oscillations fromthe oscillator I5 in the transmitter mixer 22, signals of the difference frequencies are introduced into one of the transmitter tank circuits 23. A transmitter tank circuit covering the same band of frequencies as that covered by the receiver tank circuit, which is connected in the receiver, is chosen and connected into the circuit by means of the switches 2li and 25. Switch 24 is mechanically linked by any well known means, shown diagrammatically as 2B, to the switch I3, and switch 25 is similarly linked by 21 to switch I2. Likewise, the two sets of switches operate simultaneously by means of a mechanical linkage 28.

It is well known that if -two frequencies, A and B, are mixed in accordance with the superheterodyne principle that there are tworesulting frequencies, A+B and A-B. It is common practice to choose in a receiver the A-B frequency for' further amplification and detection and to include means in a receiver for rejecting the A+B,

' or image, frequency. In the arrangement of the present invention, since the intermediate frequency of the transmitter and receiver are the saine, it is desired in the transmitter mixer 22 to select the A+B frequency in order to have the output yof that section be of the same frequency as the frequency of the signal being received by the receiver. Accordingly, filter means are provided in the transmitter mixer Z2 toremove the A-B frequency, which in that case becomes the image frequency. Such means are well known .Y 3 i and may be of conventional design; therefore, no description of them is needed in .this presen-t specifica/tion.

While there has been here described what is at present considered to be the preferred embodiment of the invention, it Will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention.

What is claimed is:

mon oscillator, a mixer stage connected to re-A l v A radio signal system comprising a receivercira cuit, a transmitter circuit and a tunableoscil-y oscillator, a mixer stage connected to receive the output of said signal oscillator, said amplifier and modulator means and said common oscillator to produce a signal representing the sum frequency of the intermediate frequency and the oscillator frequency, means .to suppress the dierence frequency representing the'dierence between the common oscillator frequency and the intermediate frequency, a plurality of band pass radio frequency circuits, each designed to cover the same'vband of frequencies covered by the band f' pass v`circuits inthe receiver, and common means celve the output of said radio frequency circuits and the output of said common oscillator to pro-l duce an intermediate frequency representing the difference frequency between a received frequency and the common oscillator1 frequency, means to suppress the frequency which is the sum frequency of the received frequency and the common oscillator frequency, and means lto amplify and detect the intermediate frequency? said transmitter circuit comprising an oscillator to produce a sign-al having a, frequency equal to the intermediate frequency produced in the receiver circuit, means to amplify said signal and means to modulate said-signal, .the aforesaid common for selecting in the receiver circuit and in the transmitterA circuit matched band pass circuits whereby said transmitter is always tuned to the same frequency as said receiver input circuits.

JOHN F. BYRNE.

REFERENCES CITED The `following references are of record in the ille of this patent:

UNITED STATES PATENTS l n -Date 2,408,826 V-Ogel Q Oct. 8, 1946