US2408370A - Automatic tuning system for radio receivers - Google Patents

Description

C. M. BURRILL Oct. 1, 1946.

AUTOMATIC TUNING SYSTEM FOR RADIO RECEIVERS Filed Feb. 26, 1945 3 Sheets-Sheet -l a z 111% r u llllll M 52 n m z p HMM M m E W mP M G m m ladlfiarrl'll M W U w @m /o MW M .15 Y. M r 1 0 P m M a M W a 0 F m M Oct 1, 1946, C BURRlLL AUTOMATIC TUNING SYSTEM FOR RADIO RECEIVERS 3 Sheets-Sheet 5 Filed Feb. 26, 1943 Iinvsntor lm ffiwrll q (Ittorneg I am: 3

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Patented Oct. 1, 1946 AUTOMATIC TUNING SYSTEM F03 RADIO RECEIVERS Charles M. Burrill, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application February 2.6, 1943, Serial No. 477,209

17 Claims. 1

Theinvention relates to a method' of and mechanism for automatically tuning radio broadcast receivers, and more particularly to a tuning system which is caused to operate automatically in accordance with and in response to a previously recorded schedule of desired programs.

One of the main objects ofthe invention is to provide a method of and apparatus for automatically tuninga radio receiver through a sequence of programsto which it has been tuned in previous weeks, in a fashion analogous to memory, without complicated preliminary selecting operations by the user;

Heretof-ore, pro-set or time tuning arrangementshaveused elaborate systems of pin jacks or-rows ofcontacts which had to: be set in advance by-the-user to select the programs to which he wished to listen. Thesehave appeared very complex to the userand have not been very acceptable commercially. In addition, the efiort to set them each week becomes burdensome and they have for this-reason fallen into disuse.

Accordinglyit-is an object of my invention to provide a tuning arrangement which is very simple as far as the user is concerned, and which requires for utilization of its automatic action little or nothing-additional to the normal opera tion of;a receiving set provided with manual tuning. I accomplish thisbywhat I have called memory tuning because thatiswhat is believed the user really wants of an automatic tuning mechanism. He'wants it"to tune in' automatically certainprograms to which he repeatedly listens, but does not want to be bothered with selecting in advance his radio schedule for an entire week.

It .is a further object of my invention to provide for changing the automatic functioning from week toweek by the operation of manual action overriding the automatic action, without the resetting of any system of contacts or other additional action; This is analogous to the building up of a habit by repeated-action, and changing it by repeated denialthrough will power. Thus, it is a further object of my invention to provid a r ceiver having. habits or memory and also willpower.

According to the present invention the method which l propose consists of automatically tuning the'radio during one week to the same stations (at given times) towhich it was tuned the previous week; and automatically shutting it off for the periods'for which it was-shut off during the previous we 5;. There is, provided also a manual control .in order tooverrulethememory operation when desired; just as oneis will ought to overrul his habit; Thus, the set-upoithe automatic action consist's merely of. normal manual opera 2 tion, when desired, to establish or revise the radios habits.

Basically, the apparatus utilizes a recording medium with a playing time of one week or more, upon which may be made a record of the re-, ceivers tunings over a weekly cycle. The reason for selecting a recording medium capable of accommodating a weekly cycle is because in the majority of cases programs are broadcast on a weekly. schedule. Some are broadcast two or three times weekly, and very few are broadcast daily. However, it will be understood that the invention may be carried out equally as well with the use of a recording medium having a playing. time of only one day, in which case memory tuning will be had only for those programs that occur daily. The record may be telegraphic, that is; it mayv consist of coded impulses. Since information is required only with regard to certain program units or intervals, for example 15 minute period, the motion of the medium is preferably discontinuous, that is, it is caused to move in small jumps every 15: minutes just prior to the beginning of anew. program, by means of a synchronous clock,

The-recording medium preferably moves in a closed cycle, in order to avoid the necessity for disposing of *used recording material and loading the receiver with new recording material. This is also desirable in that then the reproducing and recording means may be located close together along the path of record travel. However, irdesirecl a non-cyclic arrangement may be used in which case the recording material is used only once and discarded. As a result, it is necessary that the record he made anew each week, although there is no need for erasing means. However, I prefer the cyclic method, because of its greater convenience to the user. and because it does not call for continuingexpenditures for record material. In the cyclic method however, the recording material must'be capable of erasure. A suitable recording method-that may be used is the magnetic recording on a hardened steel tape, disc, drum or wire. The recording material must be driven synchronously in order toprovide accurate timing of recording and reproduction without cumulative errors, to correspond to the program cycle desired. This is easily accomplished with the aid of suitable means, such as a gear drive, from a synchronous clock motor. In the case of recording. on a steel type, suitable means such as sprockets and sprocket holes may be utilized.

As mentioned above, for American broadcasting, aprogram cycle of one week is desirable and ordinarily would require a relatively long playing time for the recording material, that is along tape, or a large disc. It is a feature of my invention to reduce the physical size of the recording material required by moving it intermittently or discontinuously with tim instead of continuously as in recording methods heretofore employed. This can be done without loss of useful performance because automatic tuning is only required during program changes, for example, every 15 minutes. Thus the program record may be moved suddenly and rapidly every 15 minutes on the quarter hour. Another feature of the invention is to make use of this rapid motion to gain sensitivity in reproduction, by causing the rapid motion of the magnetized tape through a pick-up coil to induce a relatively large voltage. The intermittent motion desired is obtained by means of a mechanism similar to the well-known step relay used in automatic telephone practice, which is actuated by contacts made by the synchronous clock every 15 minutes. A suitable indicator is provided for the record moving mechanism, so that the record may be reset to the correct time of day and day of the week in case of power failure or other cause stopping the driving clock.

Other elements that are involved in the present invention in addition to the recording medium or memory means above mentioned are means for recording on the recording medium electrical or magnetic indications which constitute a record of the stations tuned in at diiferent times, means for reproducing the record, means whereby the reproduced record effects the automatic tuning of the receiver to the same stations at corresponding times, and means for erasing the record when desired to select a different program or no program. By electrical recording is meant the process of making electrical or electro-magnetic impressions or indications on a recording medium.

The novel features characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and mode of operation together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings in which Figs. 1a and 1b when placed side by side, with Fig. la to the left, show in schematic form a complete automatic tuning system according to the invention, and Figs. 2 to 7 show details of construction of certain elements of the "memory unit.

Before describing in detail the complete system, there will first be given a description of the memory unit shown schematically in Fig, 1a and in greater detail in Figs. 2 to 7.

In Fig. 2, it is the magnetic tape upon which the record is made. It is driven intermittently, a distance corresponding to that from a to I), just prior to the beginning of each program interval, by sprocket l engaging sprocket holes in tape it which is in the form of a closed loop, suitably guided by roller 16 and other means not shown. To prevent dificulty due to irregularities in the spacing of the teeth of sprocket 15, the number of its teeth should be a factor of the total number a of program units in the loop or cycle. Sprocket i5 is driven, either directly or through a gear train, by ratchet wheel I1 and shift relay [8. Relay id is energized just prior to the beginning of each program interval by means of contacts carried on a time-operated control drum which cause a suitable operating potential to be applied to terminals Hi, all of which will be more fully described hereinafter.

Also driven with sprocket i5 is a clock indicator 20 of the type which indicates the day and the hour at quarter-hour intervals (0, 15, 30, a. m. or p. m. The indicator serves to apprise the listener of the program in progress by registering the time it goes on the air. It is also indicative of the unit portion a to b of the tape that is efiective during the program. In order that the tape position may be synchronized with the indicator at all times suitable means (not shown) may be provided for moving the tape independently of the shifting relay and the indicator.

Part l l is the reproducing head, [2 is the erasing head, and i3 is the recording head. Reproducing head H is located as near to the leading edge of the region ab as is convenient, the tape motion being in the direction shown by the arrow. Erasing head l2 follows as close as possible without causing interference with the independent action of H and I2. Recording head 13 follows with such a spacing that there is no interference between l2 and 13. The length ab is so chosen that the recording made by head 13 does not extend appreciably beyond I). The section a-b has been drawn to a much larger scale than the balance of Fig. 2, for the sake of greater clearness.

Fig. 3 shows an enlarged partial view, approximately to scale, of one form of the pole pieces which might be used for the reproducing head I l. 2! are the upper and lower soft iron pole pieces, arranged on opposite sides of the hardened steel tape it] for reproducing a transverse recording. Longitudinal recording might be used if desired, in which case they would be slightly displaced from each other longitudinally. The pole pieces are beveled as shown, to permit the reproduction of shorter impulses, and they are backed with non-magnetic pieces 22, fastened for example "with bolts 23, to prevent Wear on the tape. The pole pieces 2! are shown in contact with the tape, but with some loss of sensitivity and resolution of very short pulses, they may be held away from the tape forming small airgaps, thus further reducing wear on the tape.

Fig. 4 shows the reproducing head I l, with the complete poles 2l22 surrounded by the pickup windings H, which may be connected in series (as shown) or in parallel, in aiding phase, and brought out to terminals 25.

Erasing head 12 may be the same as reproducing head H except that the pole pieces should be considerably broader in the direction of the tape travel, for here resolution of sharp pulses is not desired, but instead a smooth magnetization or erasure of previous magnetization. Sensitivity is not likely to be of much dimculty here, so that the use of airgaps would be desirable in the erasing head. The airgaps themselves would produce the desirable effect of smoothing as with broad pole tips, because of the fringing of the flux,

The recording head I3 is the equivalent of a plurality of reproducing heads II juxtaposed longitudinally, for the purpose of recording a plurality of pulses of magnetization on the tape while it is stationary. The number of pulses required depends on the number of stations which are to be tuned automatically. The pulses should be spaced as closely as possible without overlapping. Fig. 5 shows a graph of the magnetization of a unit section ab of the tape for a case with three pulses. The line 26 represents the zero or demagnetized value, and the line 21 at the left represents the saturated or fully magnetized value corresponding to no record. The state of magnetization of the tape representing three recorded pulses is shown by the three dips at the right. For maximum sensitivity without impairment of resolution the pulses should dip down practically to zero but not beyond.

In order to provide for sensitive recording without saturation of thin poles, the arrangement shown in Figs. 6 and '7 may be used for the recording head. Fig. 6, an end view, shows the poles 2i fanned out in rotation to gain space, so that they may be enlarged in cross-section and to make room for the windings 13'. A side view is shown in Fig. '7 to make the construction clearer.

Preferably the recordingpole tips should be beveled similarly to the reproducing pole tips as shown in Fig. 3 so as to record as sharp pulses as possible and so save on the length of the tape required. For the same reason the pole pieces should preferably be in contact with the tape during recording, although they may be raised by any suitable mechanism while the tape is moved, to save wear on the tape. If the poles are left in contact while the tape is moved, non-magnetic blocks 22 should completely fill the spaces between the beveled pole tips so that a' single smooth surface is presented to the tape on each side, to minimize wear.

The plurality of windings l3 around the poles 21 of the recording head are brought out to a plurality of pairs of recording terminals 28, 3! etc. Although not shown, each of these windings is to be considered to include the winding around the corresponding lower pole, not shown.

The complete systemof my invention, shown schematically in Figs. la and lb when placed side by side, consists of the following units which are identified by legends: (a) Clock unit, (b) Controller unit, (0) Memory unit, ((1) Memory power unit, (a) Memory tuning unit, (f) Tuning mot-or unit, (g) Receiver power unit, and 2.) Push hutton unit.

Briefly the basic operation of the disclosed -ernbodiment of my invention is as follows:

1. At the beginning of each program period, the receiver is automatically tuned in accordance with the memory record. This is done regardless of how the set was tuned for the just preceding program or of whether it was on or on. If n cessary, it turns the set on .or off, a blank memory record giving the latter result.

2. Immediately after the memory record has performed its function (1) above, it is erased.

Just before the end of the program period. a new memory record is made of the station to which the receiver is then tuned. If the receiver is oil or has been tuned manually awayfiom any push-button position, no record is made.

4. The sequence is automatically self-perpetuating but the user can change the conditi i repeated for any given program period to push-button station, or off. by tuning to that station or turning the receiver off during the given period. Of several stations or ofi tried, the last is the one that will be repeated.

5. The receiver has a plurality of push-buttons. one for Manual tuning, an off button, and one for each station to be automatically tuned-in There are no controls added by the memory tuning feature, except a time setting adjustment. which must be made if the power goes off.

6. The master clock and the transformer energizing the tuning motor are on all the time.

The clock unit actuates the controller drum which controls the memory tuner and its power supply for a brief interval at the change from one program period to the next. The receiver proper is on only when in use. The memor tuning mechanism turns it on or off.

'7. The receiver is turned off by means of a push-button circuit similar to those for station tuning, which results in rotating the tuning condenser to one extreme of its travel, at which position a cam on its shaft operates the line switch. The receiver is turned on simply by tuning it either manually or automatically, away from the off position to a station.

It will be apparent to one skilled in the art, that many modifications may be made in the above basic functioning, as maybe desired, without departing from the spirit and scope of the invention. For example, additional controls may be provided so that the user may change at will various steps in the memory process, i. e. the reproducing may be prevented, the time of erasure or recording may be changed, or one or both. of these steps may be prevented, etc.

The main Power unit for the receiver the Push button unit may be similar to, or identical with such parts of modern electric motor tuned radio broadcast receivers, as for example, the RCA 911K receiver, and are shown only to indicate the complete operation of the tuning and controls. The Tuning motor unit includes the usual reversible motor M, contact making selector disk A and station-setting contact a l, al, a2 a'l, as employed in the RCA QllK receiver, and other parts to be described later. The motor M drives the tuning condenser Cr and its shaft S upon which are mounted, in addition to selector disk A. the disks 3, C, and D, the functions of which will be described later. All. other parts of the receiver proper are conventional and need not be shown.

Push-button operation of the receiver is as follows: When one of the station buttons to l is actuated, it completes a circuit through the corresponding station-setting contact al to a'i, one-half of the selector disc A, which. is connected to one side of the motor field coil, and the secondary of the power transformer 53. example, if push-button 3 is depressed, a circuit is completed from one side of the secondary of power transformer 43 to one terminal of motor M, from another terminal of motor M to one side of disc ,A, thence through contact at to push-button 3, thence through back-contact S3 of the Manual push-button, through circuit lead 88 to contact '53, segment 56, and contact l2 of the controller unit, thence to ground and the other side of power transformer 33. This energizes the motor, and the rotor is pulledforward, engaging with the gear train (not shown) that drives the shaft S, tuning condenser CT and selector disk. The condenser and disc rotate until the insulation line comes under the particular station-setting contact which in the example given is at, thereby breaking the motor circuit. Inertia carries the insulation line past the station-setting contact which th maize-s con tact to the other half of the disc. This completes the circuit to the other side of the motor field coil, causing the motor to reverse. floating flywheel (not shown) is still turning in the original direction and therefore slows down the reversal movement of the motor; as a result the selector disc is moved slowly back until the insulation line is under the station-setting contact,

when the circuit is broken and the tuning mechanism stops. For a more detailed description of the receiver automatic tuning mechanism described above and its manner of operation, reference is made to the U. S. Patent No. 2,204,065 of Beizer and Newman.

The Memory unit previously described includes the magnetic tape Hi which is moved rapidly, one section at a time, every time the shift relay i8 is excited. When it moves, electrical impulses are generated in the windings H of the reproducing head H, in accordance with the state of magnetization of the tape, recorded at the end of the earlier corresponding program period, say One week previously. After the tape passes the reproducing head it passes the erasing head l2 whose windings I 2' carry a steady magnetizing current, so that the old record is erased and the tape section is left uniformly magnetized. The section of the tape comes to rest under the recording head l3, where, just prior to the end of the program period, a new mag-- netic record is made consisting of a number of pulses, depending on the number of windings E3 in the recording head that are then excited. This is determined by the position of the tuning condenser and the contacts cl to 06 cooperatively related to the disc C in the Tuning motor unit.

The Memory tuning unit includes a vacuum tube amplifier 3B for amplifying the impulses produced at the reproduce terminals 25 of the memory unit. It in turn drives the six tube three dial scale of two counter circuit including the three pairs of thyratrons, Tl, T2; T3, T4; and T5, T6. Such counter circuits are Well known and are described, for example in a paper by C. W. Wynn-Williams, published in the Proceedings of the Royal Society, see. A, vol. 135, p. 312 (1932). This circuit counts the number of pulses following each other in rapid succession generated by the magnetic tape and holds the information until it can be used to control the step relay 3? which initiates actuation of the automatic tuning mechanism. It would be difficult to make the step relay fast enough to operate from the pulses directly, so they are in effect stored by the counter circuit and then given out at a slower rate suitable for the step relay to follow.

The counter circuit operates as follows: First, from a completely de-energized condition, the proper starting condition must be obtained, ready for the receipt of the impulses. For this starting condition one and only one thyratron of each pair must be ionized, say tubes T1, T3 and T5. The bias voltage normally applied to all of the tubes is great enough to prevent the start of ionization. Thus the starting condition is brought about by the following switching operations by the Controller unit. First, the normal bias is removed by connecting the grid returns to their grounded cathodes. Then plate potential is applied to tubes T1, T2 and T5, which thereupon ionize. Next normal bias is restored, which of course does not stop the ionization of these tubes, but does prevent the ionization of tubes T2, T4 and T6 when, as a final preparatory step, plate voltage is applied to these tubes in series with lock-out relay 38. The counter circuit is now ready to receive the pulses from the remory unit.

The bias on tubes T1 and T2 is so adjusted by means of the tap on potentiometer 39 that the positive pulses produced after amplification by tube 36, which are impressed on the grids of tubes T1 and T2, are sufficient to cause ionization of whichever tube of the pair is not already ionized. The surge resulting from the ionization of one tube of the pair puts out or de-ionizes the other one. Thus each pulse impressed on the pair transfers as it were the ionization from one tube to the other. Similarly the pair T1, T2 is so coupled to the pair T3, T4 that every time T1 becomes ionized the ionization in pair T3, T4 is transferred from one tube to the other. Likewise pair T3, T4 is coupled to pair T5, T6 so that every time T3 ionizes the ionization in pair T5, T6 is transferred. Thus as successive pulses are received, the following conditions exist, indicating the ionized state, and indicating the de-ionized state.

Tube

1 T2 T3 T4 T5 To Start After 1 pulse After 2 pulses After 3 pulses After 4 pulses After 5 pulses After 6 pulses After 7 pulses After 8 pulses It will be noted that after 8 pulses the cycle repeats itself, that only after 8 pulses are tubes T2, T4 and Te de-ionized, and that only then is the counter restored to its proper starting condition.

Use is made of this, as follows: D. C. power is applied to the step relay 3'! and to its latching coil 46, through the contacts 38 of lockout relay 33, after all the pulses have been received from the magnetic tape, say for Example 3. In this instance tubes T2 and T4 are ionized and lock out relay 38 is actuated. The are current of one tube is sufficient to operate it. The step relay 37 is provided with contacts 4! which open momentarily at each step and keep it stepping as long as power is applied. However, each step i applies a pulse to the counter thyratrons T1 and T2 through the amplitude adjusting potentiometer 42. When the sum of the pulses received from the magnetic tape and from the step relay equals 8, tubes T2, T4 and T6 are de-ionized again, thelockout relay 38 drops back and the step relay 3? is locked out until the next cycle of operation. Thus, if 3 pulses are received from the tape, the movable contact arm 3'! of the step relay will advance 5 steps from its home or off position i to the contact No. 3 and then hold its position.

The contact N0. 3 is connected to contact 113 in the Tuning motor unit, so that, after the step relay has finished its stepping, the circuit of the tuning motor will be completed through contacts at the Controller unit, and the tuning motor will tune the receiver to station No. 3 corresponding to the three pulse signal transmitted from the memory tape. When this tuning is finished the latch of the step relay is released and the contact arm 3'5 returns to the home or o position, ready for another tuning operation. As soon as the stepping operation is finished plate voltage is removed from the counter thyratrons. If no pulses are received from the tape, the step relay will not advance but will remain in the home or off position. In the corresponding position of the condenser shaft S the cam disk D is positioned to have its cam 44 open the switch 45 thereby disconnecting the power source from the Receiver power unit.

Any number of pairs of thyratrons may be used in the counter circuit, depending on the number of stations to which it is desired to tune, thus if N is the number of pairs of thyratrons, 2 is the number of positions which may be used on the step relay.

The Tuning motor unit includes the power transformer 43 which is excited all the time the equipment is plugged-in and which supplies power to the reversible tuning motor M. On the tuning condenser shaft S driven by the motor M are the four disks A, B, C and D, all mounted in fixed and equal phase, as shown in the diagram. Disk A is the station selector disk commonly used in motor tuned receivers and consists of two semicircular conductive segments, separated by an insulating strip, each segment being connected to one of the alternate o1 reversing windings of motor M. Disk C is the same as disk A, while disk B is the reverse, that is, it consists of two insulating semi-circular segments with a conducting strip therebetween. Disk D carries on its periphery a simple mechanical earn it which operates the onoif switch 15 to off at one end of the condenser travel.

Stationary contacts all, at, a2 a"! slide on disk A and are connected to the Push button unit and to the contacts i to l and off associated with the step relay of the Memory tuning unit. Similar contacts bi, b2, b3 b7 slide on disk B and are connected together and to one of the windings of the recording head 13 of the Memory unit and to one of the segments of disk C. Simiiar contacts cl, c2, o cii slide on disk C and connect each to one of the remaining six windings on the recording head. Corresponding contacts of each set, such as M, hi and cl, at, B2 and c3 etc. are fixed in phase relative to each other, that is in the same phase, but they may be adjusted together as a unit to correspond to the tuning point of any particular station desired. Contact all on disk A is fixed at one end of the tuning condenser travel corresponding to the position of the on switch operated by disk D. A contact on disk B corresponding to all and contacts on disk C corresponding to all and al are not needed and are therefore omitted.

When one of the contacts cad-a5, a2 a7 is energized, either from the Push button unit or from the step relays? in the Memory tuning unit, the motor M will operate, as previously described, to drive the tuning condenser in the proper direction until the insulating strip of disk A falls under the energized contact thereby stopping the motor. Thus the station corresponding to the energized contact is tuned in, or the oif switch 45 is operated if the on push-button was actuated, by the usual method of motor tuning.

A conductor 46 is connected between the conducting strip of disk 3 and a brush contact 51' in the Controller unit. When the circuit which includes this record power brush contact is energized by the Controller unit just prior to the end of a program period, provided one of the contacts bl, b2 bl is over the conducting strip of disk B, one, two or more windings in the recording head 23 will be energized, depending on the number of 0 contacts that happen to be on the right-hand half of the disk C. Thus if station l is then tuned in, one pulse will be recorded on the magnetic tape, 2 pulses for station 2, etc. If the receiver has been tuned manually to a position between the push-button station positions or either manually or automatically to end of the next period.

segments the off position, the conducting strip of disk B willnot be under a contact and no record will be made.

I prefer to control all the memory tuning operations by means of 2. Clock unit and a Controller unit. The Clock unit consists of a --clock' ii driven by a master synchronous motor 43 which is energized continuously from the power supply source over the line conductors 49.

The clock motor through suitable means closes the energizing circuit 551 of the drum motor 5! for a short time just before the end of each program unit when the memory tuning operations are to be accomplished. Closing this circuit releases the controller unit drum, which then is driven one complete revolution and then stops until released again by the clock at the In order that the releasing circuit 56 may be energized accurately at the proper time it is provided with two switches Sm and S connected in series, one of which, Sm for example, is closed briefly by a cam C1 once every minute and the other of which, Sp, is closed briefly by another cam C2 once every program or 15 minute period. The cams C1 and C2 are riven by the clock mechanism, preferably by the seconds and the minutes wheels respectively. Thus the drum motor energizing circuit may be closed with an accuracy of a very few seconds.

The Controller unit includes a rotary drum -52 which for simplicity of illustration is shown in Fig. lb as a development of the drum surface. The controller drum is provided on its surface with a plurality of conducting inset surfaces or 53 to 5'1, the various functions of which will be described later. For purpose of explanation the drum surface is marked oiT into longitudinal, parallel spaces corresponding to arbitrary time intervals, identified by the numerals from 0 to 15 appearing at each end of the developed drum surface. It is only necessary that the drum be active, that is, make its single revolution, during about 30 seconds, beginning just prior to the termination of one program period and ending just after the start of the next program period. It will be understood therefore that the time intervals from 0 to 15 have reference to the time of drum rotation. The various lengths of the drum segments in the direction of travel are shown to be equal to, or multiples of, a unit time as represented by any one of the equal parallel spaces. It is not necessary that such be the case, since their lengths are determined only by the time during which the respective circuits they control are required to be operative, and are merely a matter of design.

The synchronous motor 51 serves to rotate the drum by way of a shaft 58. A cam C3 mounted on or driven from the motor shaft 58 actuates the switch Cc to open the circuit of motor 51 when the drum is in the O or starting position. The contacts of switches Sm and Sp are in parallel with the contacts of switch Sc so that once the drum is started away from the 0 position it continues to turn, regardless of the condition of the clock contacts, until it reaches the Q position again, when it stops until released again by the closing of the clock contacts for the next program period.

Cooperating with the controller drum 5?. are a plurality of brush contacts E5l'l5 which ride on the drum surface and which are adapted, by contacting with the drum segments in a predetermined sequence, to individually close certain operating circuits as will be explained hereinafter. The brush contact BI is connected by way of conductor '15 to the movable contact of switch 33 which is under the control of lock-out relay 38. Brush contact 62 is connected by way of conductor ii to the latch winding 40. Brush contact 83 is connected through conductor 18 to one terminal of the lock-out relay 33, the other terminal of which is connected through conductor 59 to the plates of tubes T2, T4 and Te. Brush contact 6 is connected through conductor 80 to the plates of tubes T1, T3, T5 and amplifier 3B. Brush contact 65 is connected through conductor M to one terminal E9 of the shift relay I8, the other terminal of which is connected to ground. Brush contact 66 is connected through conductor 82 to the +3 terminal of the Memory power unit. Brush contact 6'5 is connected through conductor 56 to the conducting strip of disk B. Brush contact 68 is connected through conductor 83 to the C terminal of the Memory power unit. Brush contacts 69 is connected through conductor 84 to the control grids of the several thyratron tubes. Brush contacts and F2 are connected through conductor 85 to the ground terminal of the Memory power unit and through conductor 86 to the grounded cathodes of the tubes included in the Memory tuning unit. rush contact i! is connected through conductor 3? to the movable arm 37' which is under the control of the step relay 3T. Brush contact 13 is connected through conductor 88 to the upper contact 89 associated with the Manual push-button of the Push button unit. Brush contact it is connected through conductor 9B, the primary 9| of the power transformer for the Memory power unit and conductor 92 to one sideof the power lines 49, the brush contact being connected to the other side of the power line.

The functioning of the Controller unit switching as well as the operation of the entire system will be understood from the following:

0. Normal or starting position. In this position of the drum, the segment 55 will bridge the brush contacts "i2, i3 (push-button and ground), thereby energizing the Push-button unit and providing for push-button tuning at all times when the memory tuning apparatus is not in operation. 7

1. In this position of the drum and during the entire rotational period thereof between the beginning of time interval i and the end of time interval E5, the segment 51 will bridge the brush contacts 14, 15 (line and line), permitting power to be supplied from the A. 0. power lines 49 to the Memory power unit. This power unit is a rectifier-filter combination of the usual sort for supplying plate and bias voltages for the tubes in the Memory tuning unit, A. C. heater Voltage for these tubes, and D. C. for operating the several relays, erasing and recording windings in the Memory unit and in the Memory tuning unit. As soon as it is switched on and operating, it excites the heaters with A. C. through the secondary 93 and the erase windings l2 with D. C. by way of the conductor 9 3, without the interposition of any switches.

2. Segment 56 having been moved away from underneath the brush contacts 12 and i3, energization of the Push button unit is removed so that it cannot be operated to interfere with the memory tuning operation. Simultaneously, the lower left-hand portion of segment 53 will bridge the brush contacts 66, 6'! (+B and record power),

permitting D. C. power to be applied to the re-' cording head windings It" in accordance with the position of the tuning condenser at that instant, thus making a new memory record on a section of the magnetic tape that had been previously erased.

3. The excitation of the recording windings is removed, and by means of the left-hand portion of drum segment 5E bridging the brush contacts 69, it (bias and ground) the bias lead 84 from the thyratrons in the counter circuit is connected to ground preparatory to putting the counter ready for operation.

l. The grids .of the thyratron tubes continue to be grounded, and D. C. potential is applied to the plates of counter tubes Tl, T3 and T5 due to the connection, through segment 53, between the brush contacts 66, 64 (+B and plate #I).

5. In this position of the drum the brush contacts $8, 59 (C and bias) are bridged by segment 5 5 so that the bias on the counter tubes is given its normal negative value.

6. The brush contacts 56, G3 (+B and plate #2) are bridges by the segment 53 to permit D. C. potential to be applied to the plates of counter tubes T2, "rs and T6. The counter circuit is now ready to receive pulses.

'7. D. C. power is applied to shift relay l8 due to the brush contacts 5%, (+B and shift) being bridged by the segment 53. Energization of the relay l8 will cause the rapid movement of the magnetic tape a distance corresponding to one program period, and the generation in reproducing windings H of a number of pulses corresponding to the memory record on the tape made the Week before. The pulses are received and counted by the counter thyratrons as described previously.

8. D. C. power is removed from shift relay i8 and applied, by way of the segment 53 and the brush contacts 5%, i2 (+B and latch), to the latch winding 4!] of the step relay 37, which is now ready to step.

9. D. C. power is now applied, by way of the segment 53 and the brush contacts 66, BI (+B and step), to step relay 3'! which then steps until de-energized by the falling out of lock-out relay 38 signifying that the counter cycle has been completed. The latch winding 40 permits the step relay 3'! to hold its arm 3'? in the position to which it has been stepped.

10. The counter circuit, having thus served its purpose, is now de-energized in steps. First, the segment 53 is moved out of contact with brush contact '63 (plate #2) to remove the plate potential from thyratrons T2, T6 and T6, thus insuring against unwanted operation of lock-out relay 38 and the giving of step relay 3'! an extraneous step.

11. Next, the segment 53 is moved out of contact'with brush contact 64 (plate #I) to remove plate voltage from thyratrons Tl, T3 and T5.

The cycle of operation that has transpired up to this point will have taken place just prior to the termination of a given program period. The succeeding steps in the cycle, now to be explained, occur during the first few seconds of the next program period.

12. By movement of the segment 54 out of contact with brush contacts 68, 69 C and bias), bias is removed from all the counter thryatrons which are now entirely inactive except for their heaters which are still excited. By movement of the segment 54 out of contact with brush contact of the pair 38' associated with lock-out relay -38.

Bridging-of thebrush contacts ii, iii (memory 'tune-and'ground) by the segment 55 causes the motor circuit to be'completed, thus exciting the tuning motor M which .tunes the receiver to the ing contact between segment '53 and brushes 62, 66 (latch and +B), thus permitting the movable contact '3 to return to its home or off posi tion, ready for the next tuning.

"15. Energization is reapplied by the segment 55 to the Push button unit through the brush contacts i2, it, now that the memory tuning is finishedfor another program period, so that push button tuning is again available.

0. Contact between segment and brush contacts 1'4, (line and line) is broken, causing A. C.-excitation to be removed from the Memory power unit, removing heater excitation from the tubes in the Memory tuning unit and D. C. from the erase windings l2, and putting everything -back to the normal or starting position. The cam 03 on the controller driving motor shaft opens the switch Sc, stopping the controller drum. The clock contacts are already open, and the entire memory tuning apparatus is shut down, awaiting the closing of the clock contacts just prior to the end of the next program period. Only the clock, the tuning transformer 53 and the set proper (if in operation only) remain excited.

It is to be noted that the lock-out relay 38 should be slow enough in action so that it will not follow or chatter with the action of the individual thyratrons in counting the pulses from the memory tape, but will pull up promptly after they have all been received, before the controller unit applies'power through brush contact 6! and conductor lfi'to'the contacts 38' of the lock-out relay "38 and the step relay 3?. Likewise the lock-out relay 38 must be faster in dropping out than the steps of step relay 3? so that the step relay does'not get in an extra step after it should have been locked out'by the opening of the contacts 38 "by the look-out relay 38.

While I have shown a particular embodiment of my invention, it will of course be understood that I do not wish to be limited thereto, since various modifications may be made both in the circuit arrangement, in the instrumentalities, and in the mechanical construction employed without departing from the spirit and scope of my invention as set forth in the appended claims, and I contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim is:

l. The method of effecting the automatic tuningof a radio receiver to selected stations according to a predetermined schedule, which consists in causing during the reception period of each tuned-in station the automatic production of a characteristic electro-Inagnetic recording which is. different for each tuned-in station, and thereafter causing said electro-magnetic recordings to automatically control the operation of the receiver in accordance with said predetermined schedule.

2. The method of automatically controlling the operation of a radio receiver according to a predetermined schedule, which consists in first manually operating the receiver to tune in a plurality'of stations in accordance with said schedule, causing during the reception period of each manuallytuned-in station the automatic production of -a characteristic electro-magnetic recording which is'different for each tuned-in station, and thereafter causing said electro-magnetic recordings to automatically control the operation of the receiver in accordance with'said predetermined schedule.

3. The method of automatically controlling the operation of aradio receiver in accordance with a schedule determined by previous manual operation of the receivenwhich consists in automaticaily making an electro-magnetic record corresponding to said previous manual operation, and. thereafter causing the record to automatically control the operation of the receiver in accordance with the recorded schedule.

4. The method of automatically cyclically-tuning a radio receiver to receiv 'the same program which is broadcast at regular intervals, which consists inelectro-magnetically recording at the close of the program an indication corresponding to said received program, causing the recorded indication to be ineffective until the next interval whenthe program is to be transmitted, utilizing the recorded indication just prior to said next interval to tune the receiver to said program, then voiding the just used recorded indication, and electro -magnetically recording at the close of said next interval another indication corresponding to the program for use to tune the receiver at the next succeeding interval.

5. Tuning mechanism for a radio receiver adapted to-automatically tune in a desired broadcasting-station at recurring time-spaced intervals, comprising an electrical recording medium, means for electrically automatically recording on said recording medium during reception from said station an indication corresponding to the station, a timing device for actuating the recording medium to enable th recorded indication to be effective at the next recurring interval, and means actuated at the said next recurring interval in response to said effective recorded indication for automatically tuning the receiver to the desired station.

'6. Tuning mechanism for a radio receiver adapted to automatically tune in a desired broadcasting station at recurring time spaced intervals, comprising an electrical recording tape, means for electrically automatically recording on said tape an indication corresponding to the station each time the same is received, a timing device for actuating the recording tape to enable the recorded indication to be effective at the next recurring interval, and means actuated at the said next recurring interval in response to said effective recorded indication for automatically tuning the receiver to the desired station.

7. Tuning mechanism for a radio receiver adapted to automatically tun in a desired broadcasting station at recurring time-spaced intervals, comprising an electrical recording tape, means for electrically automatically recording on said tape, during the final portion of the reception period of the station each time the same is received, an indication corresponding to the station, a timing device for actuating the recording tape to enable the recorded indication to be effective at the next recurring interval, and means actuated at the beginning of the said next recurring interval in response to said effective recorded indication for automatically tuning the receiver to the desired station.

8. The combination with the tuning device of a radio receiver, of means for automatically actuating the tuning device to tune in a sequence of broadcasting stations at predetermined future times, said actuating means comprising a magnetic recording wire, means for sequentially automatically recording on said wire, during the reception of said stations and for use in the future, magnetic indications which correspond respectively to said stations, a timing device for actuating the magnetic recording wire, and means successively actuated at said predetermined future times, in response to the respective recorded indications, for operating the tuning device actuating means to tune in said sequence of stations.

9. The combination with the tuning device of a radio receiver, of means for automatically actuating the tuning device to tune in a sequence of programs which are broadcast at regular intervals and. to automatically repeat said sequence as often as desired at other future times, said actuating means comprising electrical recording mechanism including a magnetic tape upon which there are sequentially recorded, during the receipt of each program and for use at said future times, electrical impulses corresponding to that program, a timing device for moving the magnetic recording tape, and program selecting means successively actuated at said future times in response to the recorded electrical impulse for operating the tuning device actuating means.

10. The combination with the tuning device of a radio receiver, of means for automatically actuating the tuning device to tune in one of a plurality of predetermined stations, means for recording electrical impulses, means movable with the tuning device for determining the number of impulses to be recorded by the recording means, said predetermined stations being identified each by a different number of impulses, and a timing device for actuating the recording means and the tuning device actuating means to tune in th station corresponding to the number of impulses recorded by the recording means.

11. The combination with the tuning device of a radio receiver, of means for automatically actuating the tunin device to tune in one of a plurality of predetermined stations, means movable with the tuning device for generating a number of i impulses corresponding to the station to be tuned,

means for recording said impulses, means for reproducing the recorded impulses and causing the reproduced impulses to operate the tuning device actuating means to tune in the station corresponding to the number of recorded impulses.

12. The combination with an electric motortuned push-button radio receiver, of means for automatically recording a number of impulses corresponding to th station tuned in by any one of the push-buttons, and means operative at a corresponding future time for reproducing the recorded impulses and causing the reproduced impulses to actuate the electrically-operated re ceiver to tune in the station corresponding to. the previously actuated push-button.

13. The combination with an electric motortuned push-button radio receiver, of time-controlled means for automatically recording successive numbers of impulses which correspond to the stations tuned in by the push-buttons, said stations being identified by different numbers of impulses, and means operative at corresponding future times for reproducing the recorded impulses and causing the reproduced impulses to operate the electrically-operated receiver to tunein in sequence the several stations corresponding to the previously actuated push-buttons.

14. The combination with the tuning device of a radio receiver, of mechanism for automatically actuating the tuning device to tune in a sequence of programs which are broadcast at regular intervals and to repeat said sequence as often as desired at other future times, said actuating mechanism comprising electrical means for driving the tuning device to selected predetermined positions corresponding to the desired programs, electrical recording means including a magnetic tape upon which there are sequentially recorded, during the receipt of said programs and for use at said future times, electrical impulses corresponding to said programs, means for imparting a step-by-step movement to the magnetic recording tape, means for reproducing the recorded impulses and for causing the reproduced impulses to actuate the tuning device driving means, and control means operative to control the sequence of operation of said several means.

15. The combination with the tuning element of a radio receiver, of means for automatically actuating the tuning element to selected positions corresponding to predetermined stations, means movable with the tuning element for generating a number of impulses corresponding to the station to be tuned, means for recording said impulses, means for reproducing th recorded impulses, means operated in response to the reproduced impulses for actuating the tuning element to a selected position corresponding to the number of impulses, and control means operative to control the sequence of operation of said several means.

16. The combination with the tuning element of a radio receiver, of means for automatically actuating the tuning element to selected positions corresponding to predetermined stations, means movable with the tuning element for generating a number of impulses corresponding to the station to be tuned, means including a magnetic tape for recording said impulses, means for reproducing the recorded impulses, means including an impulse counter operated in response to the reproduced impulses for actuating the tuning element to a selected position corresponding to the number of impulses, and time-controlled means adapted to efiect the operation of said several means and to control their sequence.

17. The combination with the tuning element of a radio receiver, of means for automatically actuating the tuning element to selected positions corresponding to predetermined stations, means movable with the tuning element for generating a number of impulses corresponding to the station to be tuned, means including a magnetic tape for recording said impulses, means for reproducing th recorded impulses, means including an impulse counter circuit operated in response to the reproduced impulses for actuating the tuning element to a selected position corresponding to the number of impulses, a source of power supply for energizing said several means, and time-controlled means including a commutator drum operative to control the operation of said several means in a predetermined sequence.

CHARLES M. BURRILL.

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