US2071733A - Reception system - Google Patents

Description

R. c. CURTIS 2,071,733

RECEPTION SYSTEM Original Filed June 12, 1934 5 Sheets-Sheet l Feb. 23, 1937.

Wm M u p yfinfiim d 526m J m N 2 nunnu m- IV I! I, F l.|:l:. l.|! 1 li. U .75 W J 3 l m E M g i u 6cm on Feb. 23, 1937. R. c. CURTIS RECEPTION SYSTEM Original Filed June 12,1934 7 3 Sheets-Sheet 2 I N 'll Richard [1. EurtiS Feb. 23, 1937. R c URT|$ 2,071,733

RECEPTION SYSTEM Original Filed June 12, 1934 3 Sheets-Sheet 3 x L mo 80- Q "g; v// ffi:

12o I I I 140 I I FREQUENCY IN KILDCYCLES Richard II. Buriis.

Patented Feb. 23, 1937 UNITED STATES PATENT Y OFFI. ,C.E

RECEPTION SYSTEM tion of Delaware Richard 0. Curtis, East Orange, N. ,J.,.assignor to Wired Radio, Inc... New York, N. Y., a corpora- Original application June 12, 1934, Serial No. Y I 2 730,211. Divided and this application January 9, 1935, Serial No. 94,8 v

1 Claim. (orzso- -zo) i My invention pertains in. general to radio receiving systems and specifically relates to a universal receiver for receiving programs under varying conditions, this being a divisional of my application Serial No. 730,211, filed June 12, 1934.

One of the objects of my invention consists in providing a radio receiving system having means for effecting the reception of signals from differently characterized sources.

Another object comprises providing a receiving system, having means for improving the quality of reproduction by having a plural resonance accentuation of the response at certain frequencies.

A further object comprises providing a filter system of the inductively coupled type in which variation of frequency band width can be accomplished without the aid of switches or like devices.

A further object consists in providing a receiving system in which a characteristic frequency reception curve having staggered or an odd number of resonance peaks is varied in width by commonly mechanically moved electrical units having no conductive electrical connection with the other circuits in the system.

These and other objects will be apparent from the following, reference being had to the accompanying drawings in which like reference numerals designate corresponding parts throughout and in which:

Fig. 1 is a schematic representation of the circuit system employed in my invention;

Fig. 2 is a representation of one embodiment of the mechanical structure employed in part of my receiving system;

Fig. 3 is a horizontal sectional view along the line 3-3 of Fig. 2;

Fig. 4 is a horizontal sectional view along the I line 4-4 of Fig. 2; and

Fig. 5 is a graphical representation of certain characteristics of the receiving system according to my invention.

My invention contemplates providing a radio receiving system, preferably of the superheterodyne type, in which the input and output of the intermediate frequency amplifier includes filter networks of the inductively coupled type. Within each filter, according to my invention, there is provided a circuit unit including the primary of one radio frequency transformer and the secondary of another radio frequency transformer. The

primary and secondary are interconnected to have special resonance characteristics and are also specially mechanically mounted so that the primary and secondary coils can be moved relative to their associated windings to vary coupling effects. and thereby accomplish variations in the i overall frequency transmission band offreque'ncies being handled'by' the intermeditmteirequency amplifier. The transmission characteristics of these filters are such thatthey simulatethe effect of an odd number of resonance circuits staggered with respectto each other alongzthe frequency spectrum. Although various odd numbersof such resonance peaks may be employed according to my invention, I prefer, in the presentembodiment, to illustrate theme of a system characterized by three such peaks. z

Referring to' the drawings .in' detail, and particularly to Fig. 1, the mixeri :isconnected with circuit means usuallyto .be found in a superheterodyne receiver ahead. of theintermediate frequency amplifien This circuit means. connected with the mixer I includes a high frequency amplifier and high frequency reception circuits as well as the local oscillator for producing oscillations to beat with the received high frequencies to produce the intermediate frequencies for reception over the intermediate frequency amplifier. The output of the mixer l is directed to an input filter circuit 2 which is of the inductively coupled type and includes an inductance 3 coupled with inductance 4 and inductance.. ,5 coupled with in.-

ductance 6. Avariable capacitor 1 is incircuit with the inductance 3 while a variable capacitor .8

forms; part of the circuit connections betweeninductances 4 and 5.1 ,Anothervariable capacitor!) is connected'in circuit withwthe. inductance 6. These capacitors are'of the'trimmer type usually to be found in such organizations. The inductance 6 forms part'of the filter output circuit which includes aterminating impedance l0 and is connected with the input of the intermediate frequencyamplifier proper which includes an electron amplifier tube l2. The output of electron amplifier tube i2 is connected, with the input of the output filter circuit which is similar to the input filter circuit 2. The output of this filter circuit l I is then connected with the usual detector and audio amplifiersystem'i l and thence to a reproducing loud speaker It. A power supply I1 is provided in the usual manner for energizing the various electron tubes aswell as the loud speaker l5.

Referring to Fig. 2, the mechanical structure of a portion of the receiving system will now be considered. The inductances 3 and B are mounted'on supporting members 22 and 23 which are secured to a mounting member 24. A shielding element '21 extends between the coils-3 and 6 as shown.

Cells 3 and 6 are positioned for inductive coupling The entire mechanical structure thus described is mounted within an enclosing shield 30. The shaft 29 extends through the mounting member 24 and is mechanically integral with a crank 3| which is connected with a reciprocative member 32 so that reciprocative forces from member 32 can be translated into rotary motion of 1 the shaft 29. Such rotary motion causes the'spatial relationship between the coils 3 and 4 and between the coils 6 and to be varied, thus varying the inductive coupling between these coils. 'This' condition may be seen particularly in Fig. 3 in which the coils have been so rotated.

Referring back to Fig. 1, it will be seen that the reciprocative member 32 is provided'for interconnecting the rotatable shafts 29 and 29a in the two filter systems on the input and output sides of the intermediate frequency amplifier tube. By such an arrangement, it is possible to vary the coupling in both filter systems in unison. Any convenient form of knob or dial can be utilized for. controlling the movement of theshaft 32 in the structural arrangement of theradio receiver.

Referring to Fig. 5, consideration will now be given to the electrical characteristics of the radio receiver of my invention. The curves X, Y, and Z are a family showing the transmission frequency characteristic of my radio receiving system for different degrees of coupling produced by different rotative spatial relationship of the coils 4 and 5 in the filter 2 and filter H. Referring first to curve Z, it will be seen from the curve that the frequency band width here is quite wide, while the frequency band width of curve X is relatively narrow, the curve Y being intermediate such widths. The curve Z represents close spatial relationship of the inductance while the curve X represents the opposite. Thus, when it is desired to receive a narrow band of frequencies for program reception purposes, the shaft 32 may be moved to vary the spatial relationship of the coils 4 and 5 with respect to their associated coils so that the frequency transmission of the filter assumes a characteristic such as represented by the curve X. On the other hand, to obtain a wider band of frequencies, the spatial relationship of the coils may be adjusted to obtain a characteristic represented by the curve Z. It is an especial feature that the mechanical structure of my invention makes it possible to maintain the filter circuits as a structural unity with the variable means enclosed as a single moving unit Without any physical or conductive connection with the rest of the filter circuit, thus avoiding the use of movable contactors and inductance taps and the like.

It will be seen that the curve Z has substantially three resonance peaks at the points Za, Zb and Zc, while the other curves X and Y have similar resonance peaks but not quite so pronounced, due to the narrower width of these bands. It is known in the art that filter circuits can be adjusted to achieve certain resonance characteristics and in accordance with my invention the filter circuits in my system are adjusted to produce the resonance characteristics indicated in Fig. 5. It will of course be understood that other types of circuits can be employed using other arrangements of other networks. For example, I might employ a long series of coupled circuits as Well as other forms of networks. I have found that such an arrangement of resonance peaks offers considerable improvement in quality. The attenuation of the side bands corresponding to modulation frequency at around 2300 to 3000 cycles tends to compensate for the increase in response which is usually present in loud speakers at these frequencies. The speaker [5 has such a resonance characteristic. Another feature is that the carrier is not attenuated with respect to the side band frequencies and so does not tend to produce distortion in demodulation at high precentages V of modulation.

For certain purposes, in accordance with the principles of my invention, the terminating impedances I0 and Mia of the filter systems 2 and I I may be adjusted in mechanical unison with the adjustment of the spatial relationship of the inductance coils in these filter systems as accomplished by the member 32. The relative amplitude of the resonance peaks is a function of the terminating impedances. In accordance with my invention, therefore, the values of the terminating impedance for each filter system may be made variable so that a strict proportionality I can be maintained between the reactance values in each filter circuit and the respective value of terminating impedance. It should also be noted that the three resonance peaks may be made to vanish by using a suitably low value of terminating impedance.

It will now be apparent that I have provided a novel form of receiving organization which is directed to both improvements in electrical reception characteristics and in mechanical arrangements for producing variable band effects in selection operation. Although I have shown a preferred embodiment of my system it will be apparent that changes can be made therein by those skilled in the art without departing from the intended scope of my invention. I do not, therefore, desire to limit myself to the foregoing except insofar as may be pointed out in the appended claim.

What I claim as new and desire to secure by Letters Patent of the United States is:

A radio receiving organization comprising, operativeiy associated, an input super-audible frequency system and intermediary super-audible frequency system, a detection and audible frequency amplification system, a loud speaker with a reproducing characteristic accentuated at certain frequencies, said intermediary super-audible frequency system including an electron am-' plifier tube having input and output circuits and coupling means having a frequency responsive characteristic having attenuation to restrict the intermediary super-audible frequencies positioned in that part of the frequency spectrum which will compensate for said accentuated audible frequencies of said loud speaker and comprising two link circuits respectively coupling the input circuit and output circuit of said electron amplifier tube with said radio receiving organization solely by induction and being otherwise conductively isolated from said radio re ceiving organization and means for varying the physical relation of said inductive couplings of position to effect compensation for said audible frequency accentuation of said loud speaker to produce substantially uniform reproduction of the audible frequencies derived from said detection and audible frequency amplification system. 5

RICHARD C. CURTIS.

Images