US2229324A

US2229324A - Timing apparatus

Info

Publication number: US2229324A
Authority: US
Publication date: 1941-01-21
Anticipated expiration: 1958-01-21

Description

Jan. 21, 1941. G, H, GORDON 'rIMING APPARATUS 2 Sheets-Sheet l Filed March 1. 1958 caf/4 INVENTOR Gram/160550# ATTO R N EY Jan. 21, 1941. G. H. GoRDoN 2,229,324

TIMING APPARATUS v Filed March 1, 1958 2 Sheets-Sheet 2 Patented Jan. 21, 1941 l u t UNITED STATES PATENT OFFICE l'rIMING ArrAnA'rUs George Henry Gordian, New York, N. Y., assignor, lirfiesne assignments, to Paul Kent, Altedena,

Application March 1, 1938, Serial No. 193,225 19 claims. (c1.2s4-3s.5)

This invention relates to timing apparatus, tenna may extend overhead or be buried undermore particularly for timing travelling objects, ground. The spaced antennas at the various and especially for race timing. timing points about the track are interconnected The primary object ofv my invention is to genby a suitable transmission line. A bank of rey erally improve apparatus of the character' speciceivers is connected to the transmission line, each 5 ned. A more particular object is to provide apreceiver being selective to the characteristic freparatus for timing a moving object or animal,V quency of one of the oscillators. Theseselective suchasaracing auto, or horse. For convenience, receivers control their own individual tape I shall refer in the speciiication to horse racing recorders and timing clocks.

as a particular example. Another object is to A further object or my invention is to obtain 1 time the horse` at a plurality of spaced timing an exact measure of the passage of the oscillator points, thus enabling a more accurate study of at the timing point. Tothe attainment of this v the progress and characteristics of 4the'horse, at object, VI employ two antennas at each timing eighthmile or sixteen-th mile, or other convenient point, these being disposed in substantially intervals. .In accordance with a still further equally spaced relation on opposite sides of the 15 feature and object of the'invention, the progress theoretical timing point. The leading. antennas and timing of the horse at the specified intervals of each pair are connected by one transmission is permanently recorded on a travelling tape on line, and the trailing antennas of each pair are which a standard timing wave lmay also be connected by another transmission line. 'The 2 IeCOrded, thereby -producing a record which is energies from the transmission lines are combined 20 both permanent and extremely accurate. This at each receiver in phase opposition, and in this record is suitable for subsequent study of the way, the energies neutralize and cancel one anperformance of the horse. It may also be disother at thetiming point halfway between the played to spectators at' the track by projection. antennas constituting a Pair 0f aDtEDDBS- A true A further object. of the present'invention is to zero reading is obtained at this point, and that 25 provide 'direct timing or clocking 0f the horse. zero is emplOyed t0 mark the Passage Ofthe tim- Clocks may be set up in Athe judges stand, and ing point 0n the track large display clocks may be set up in front of the Further objects oi my invention center about grands'tand. The clocks are started at the be.' the clock for direct timing of the horse. I prefer 3 ginning of the run and are automatically stopped to employ an electric clock of the synchronous 3 at a selected timing point corresponding'tq the motor type. Such clocks are accurate and are end of the run, thereby instantly displaying the readily Started at the beginning 0f the race by time taken for that particular run. simply closing the alternating Current Supply cir- I have so far written in terms of a single horse, cuit thereto simultaneous with the start of the and the invention is well adapted to timing-and race. The TeleChI'On I nOtOr used fOr this pur- 35 clocking a. single horse during trial runs, for, as pose is, 0f course, 0f the Self-Starting type- I nd above explained, the record shows not only the that it is not' sufficient to merely interrupt the total elapsed time, but also, the timing and supply circuit at-the end ofpthe race, for there progress at different intervals in the course of i's a tendency for the motor to coast -and the clock the complete run. However, the invention is t0 0Verr11n- It iS important t0' lock the 6100K 4 applicable to actual races in which there are a against continued rotation at the end of the race, number of horses running at the same time, and, and a further Object 0f my invention iS t0 a0- in accordance'with a feature and object of my complish this result in a convenient and dependinvention, a tape record and display clock timing able manner. I iind that the motor is locked is obtained for each of the horses running in the againSt C0ntin11ed rotation if Supplied Withdireet race. v current instead of alternating current, and, in

In furtherance oi the above objects, I provide 'aCCOrdan'Oe With my inVentOn, this result may be each horse with an exceedingly compact miniaobtained by supplying the alternating current to ture radio frequency oscillator or transmitter. the clock through appropriate rectifying means, 50

These oscillators are negligible in weight and are said means being normally shunted by closed constandardized and calibrated in frequency so thatV tacts, which contacts are, however, opened at the each has a characteristic frequency dierent from end of the run, thus converting the alternating the others. An appropriate antenna is disposed current supply to direct current, and so not only cross the track at each timing point. This anstopping but freezing the clock in proper posi- `55 tion. A further object of my invention is to prevent stoppage of the clock when. the horse passes any one of the timing points or antennas preceding the terminal timing point corresponding to the end of the race. With this object in view, I provide a step relay which is connected to each receiver and which is stepped up as the horse passes the successive timing points until it passes the timing point preceding the desired terminal timing point corresponding to the end of the race. At this time, the step relay functions to so connect the receiver to the contacts shunting the clock rectifier that the contacts are opened when the horse passes the next or terminal timing point. The clock is thus supplied Withv direct current and is thereby' locked against movement.

To the accomplishment of the foregoing and other more detailed objects which will hereinafter appear, my invention consists in the radio transmitting, receiving, and timing elements and their relation one to the other, as hereinafter are more particularly described in the specification and sought to be defined in the claims. 'I'he specification is .accompanied by drawings in which:

Fig.` 1 isfa schematic plan view of a race track and is explanatory of my invention;

Fig. 2 is a graph explanatory of the manner in which the energies from the leading and trailing antennas may be combined in phase opposition after rectification;

Fig. 3 is a graph explanatory of how the radio frequency energies may becombined in phase opposition -before rectification;

Fig. 4 illustrates a piece of recording tape:

Fig. 5 shows the coupling of a leading antenna to its transmission line;

Fig. 6 shows the coupling of a trailing antenna to its transmission line:

Fig. 'l is a wiring diagram explanatory of a re-.

-ceiver for controlling a recorder and associated with relay mechanism for controlling an electric timing clock;

Fig. 8 illustrates a modification of the apparatus shown at the left-hand part of the ,diagram of Fig. 7, the apparatus being modied to oombine the energies from the leading and trailing antennas after rectification;

Fig. 9 is a wiring diagram for a simple form of oscillator carried by the horse; and

Fig. 10v is a schematic diagram explanatory of the clock control circuits. i

Referring to the drawings, and more particularly to Fig. 1, the invention is shown applied to a race track I2. Pairs of antennas I4 and I6 are arranged transversely of track I2 at preferably equally spaced intervals about the track. For convenience in understanding thev diagram, the leading antennas I4 have beenshown in solid lines and the trailing antennas I6 have been shown in broken lines, but it will be understood that, in actual practice, these antennas are alike.

I'Ihey may be Vdisposed overhead, so that the horses or other racing objects run beneath the antennas, or they may be buried somewhat underground. It will be understood that each pair of antennas corresponds to a timing point which is located exactly halfway between the antennas, neglecting, for the moment, the question of oscillator location on the horse. In practice, the timing points are first .selected and marked, these timing points being, say, at sixteenth mile intervals, or at any other convenient interval. The antennas are then disposed at equal distances on antennas.

opposite sides of the timing point (or adjusted distances. as later described). For convenience of reference, I refer to one of the' antennas in each pair as a leading antenna and the other as a trailing antenna.

The leading antennas I4 are all connected to a common transmission line I8 running about the track. Similarly, the trailing antennas I6 are all connected to a common transmission line 20, also running about the track. Transmission lines I8 and 20 have each been shown as a single line, but it will be understood that, in practice, each comprises a pair of conductors. Thus, referring to Fig. 5, it will be seen that antenna I4 is grounded at 22 and is coupled by a suitable radio frequency transformer 24 to transmission line I8 made up oi' a pair of

conductors

24 and 26. Referring to Fig. 6,11: will be seen that the trailing antenna I6 is similarly coupled to transmission line 20 by grounding the antenna at 28 through the prim-ary of a radio frequency transformer 20, the secondary of said transformer being connected to the

conductors

32 and 24 of the transmission line 2n.

Reverting now to Fig.' 1, I provide a bank of

receivers

36, 38, 40, etc., at any convenient point about the track. 'Ihere is one such receiver for each entry in the race. Each receiver-is in reality an assembly of units. Thus, referring to Fig. 1, the receiver assembly 36 comprises a first radio frequency selective amplifier 42 connected to transmission line I8, and thus connected to the leading antennas. It further comprises a similar selective radio frequency ampliner 44 connected to transmission line 20, and .thus to the trailing These amplifiers are selective to one only of the travelling oscillators, and the entire receiver assembly 36 is used to record and ti'me that oscillator alone. The amplifiers 42 and 44 terminate with rectifiers, and the rectified outputs are combined in phase opposition in a suitable combining unit and tape recorder schematically indicated by box 46.

Referring now to Fig. 2, the rectified output from amplifier 41 rises and falls, as is indicated by the wave 48, as the oscillator passes the leading antenna I4. Similarly, the rectified output from amplifier 44 rises and falls, as is indicated by the wave 60, as the oscillator passes the trailing antenna I6. 'I'he spacing of the antennas is less than the radio range of the travelling oscillator, and the waves V48 and 50, therefore, overlap. The energies indicated by the

waves

48 and 50 are combined in phase opposition, and this is schematically indicated by the dotted line wave 50'. It will thus be seen that, at a point midway between the antennas I4 and I6, that is, at the timing point 52, the rectified energies neutralize and Vcancel one another, thus bringing the actual energy applied to a recorder, stylus, or other such device, down to true zero value. The summation or combined wave is indicated by the dot-and-fY dash line 54. Y

Referring now to Fig. 4, the strip of tape 54 is moved through a recording apparatus at a preferably uniform speed. A line 51,6 is traced thereon by a stylus which is responsive tothe energies from lthe transmission lines combined in phase opposition, as was explained in Figs. 1 and 2. When the oscillator passes beneath a leading antenna, the stylus is displaced and traces 'a wave, such as that indicated at 48. When the oscillator passes a trailing antenna, the stylus is displaced in opposite direction and traces a wavesuch as that indicated at 56'. Between the antennas, the stylus traces the combined line 54. The point of intersection 52 of line 54 with the zero line 64 marks the passage by the oscillator of the theoretical timing point on the track, this timing point being midway of the pair of antennas. A standardized timing wave 66 of uniform periodicity may be traced on tape 54.by another stylus, and the timing of the horse between timing points may be computed .against the timing wave 06. This obviates any error which might otherwise result from variation in the rate of feed of tape 54 through the recording apparatus.

It is also possible to combine the energies from the transmission lines while still in radio frequency form. I prefer to use radio frequencies of moderate amount, say, 1 to 100 microvolts, and corresponding to a wavelength oi,` say,

200 meters or up, and this very greatly exceeds the contemplated spacing between the trailing and leading antennas I4 and I6. It is, therefore,

possible to ignore the matter of space change of phase in the radio wave radiating from the oscillator as it moves between the leading and trailing antennas. It may be mentioned, however, that, if any attempt is made to use oscillators which radiate ultra-short waves, it would then be necessary to combine the .energies after rectification, as previously explained. v

Assuming the use of the above relatively long wave-lengths, the energies from the transmission lines may be applied in phase opposition directly to the input of a single radio frequency amplifier. This is the essential difference between Vthe arrangements of Figs. 'I and 8, for, in Fig. 8, separate radio frequency ampliers and rectiflers are employed, while in Fig. 1, the radio frequency energies are applied in phase opposition 4to a single amplifier and rectifier. Referring now to Fig. 3, the curve 10 represents the envelope of the combined radio frequency waves from leading antenna I4 and trailing antenna I6. The combined wave falls to zero at the mid-point or timing point 12, but, in this case, both sides of the wave lie on the same side of the zero line 14. It

will be understood that the curve 10 may be considered representative of the envlope` of the combined radio frequency wave, or it may also be considered representative of the rectified output resulting from the combined radio frequency wave.

Referring to Fig, l, each receiver assembly has a display clock or/and judges clock associated with it. Thus, in receiver assembly 36, the clock is schematically indicated at 10. 'I'he clocks are all connected to an appropriate starting switch 18, and it will be understood that this starting switch is closed and the entire bank of clocks is started simultaneously with the start of the race. Each receiver assembly and clock corresponds to one of the oscillators, and the problem is'tostop the clock when its corresponding oscillator passes a desired one of the timing points corresponding to the end of the race.' A further problem is to prevent stoppage of the clock as the oscillator passes timing points ahead of the terminal timing point.

The manner in which this is done may be preliminarily explained by reference to the schematic diagram of Fig. 10. Theclock 10V (along with all of the other clocks) is'started by an appropriate starters button or switch 18. The clock 15 is arranged to run in parallel with a judges clock 16', and both are stopped by an appropriate stop circuit 80. Thisstop circuit is controlledby a receiver connected to line 82. However, between the receiver and the stop vcircuit 80, I interpose step relay mechanism 84.. This step relay mechanism functions to absorb, in 'a harmless or non-functional manner, the impulses produced as the mating oscillator passes the timing points preceding the terminal timing point. The relay is merely stepped or notched upwardly for each timing point (or twice, one for each antenna), until a critical step is reached, at which time the receiver may be connected to the stop circuit so that the clock will be stopped when the oscillator passes the next timing point. The critical step referred to depends on the length of th'e race and the spacing'. of the timing points, and is variably (selective.

Referring'now'to the more detailed wiring diagrams, the travelling oscillator may be entirely conventional. It is preferably a vacuum tube oscillator of compact design, using miniature dry cells, and -a typical circuit suitable for the purpose is shown in Fig. 9. The frequency is determined by tuned circuit 86, and this circuit is calibrated and sealed so as to denitely identify the horsecarrying the oscillatorin question. Regeneratlon'is obtained by means of coil 88 coupling the output circuit of oscillator tube, 90 with the tuned input circuit 86. The filament is heated by dry cell 92; the plate is polarized by battery 94; and the grid is suitably biased by means of a condenser and

resistance combination

96, 98. Other oscillator circuits of known type may be employed. No special antenna for radiating the transmission energy is needed, for the` transmission distance is very small, the receiving antenna,

whether located underfoot or overhead, being.

quite close to the oscillator.

The wiring diagram for. a receiver circuit is shown in Fig. '1. I provide a two-stage radio frequency amplifier employing the tubes |00, |02. These tubes may be of the screen grid type, known commercially as type 6D6. The tuned input circuit' of tube |00is indicated at |04, and this is coupled to the transmission lines I8 and 20 through tuned coupling circuits |05 and |08.- If the transmission lines are grounded on one side, ,the circuit |06 may be connected to one line through conductor ||0 and grounded at ||2, 'while circuit |08 is connected ,to the other line through conductor ||4 and is grounded at ||8. In Fig. 5, I show conductor 26 grounded, and in Fig. 6, I show conductor 34 grounded, and it will be understood that, in actual practice, a common conductor may be used instead of separate conductors 28 and 34. The feed of the radio frequency energies to input circuit |04 is in phase opposition, as the diagram indicates. The cirl cuits |06 and |00 may be connected to the two wire transmission lines, if four conductors are used, by the additional connections ||8 and |20,

precaution being taken, of course, to see that the y i,

energies are combined in opposed phase.

The amplified output of tube |00 is fed to-the input of tube |02 through coupled circuits |22, |24, and the amplified output of tube |02 is fed to rectifier tube |20 through coupled circuits |28 and |29.` The gain of the radio frequency am: plier may be varied by volume control resistor |0I, preferably shunted by condenser |03. Practically al1 of the tubes shown in the drawings are of the cathode heater type, and it is merely for simplification of the drawings that I have omitted the heater filaments and supply circuits therefor. 'Ihese may be wholly conventional. The tube |26 is a dual diode triode, which may be of the type known commercially as #'75, and which functions both asa diode rectifier and as an amplifler for the rectified energy. The rectified output is taken oi the diode circuit across a resistor |05, and is applied to a suitable tape recorder |01 functioning generally as was previously described f in connection with Fig. 4, except that, in this case, the timing wave will be of the character shown in Fig. 3, rather than of the character shown in Fig. 4. Condenser |09 and resistor form a filter for the radio frequency energy. Resistor ||3 is not essential but is merely a stabilizing resistor for the tube.

The rectified potential across resistor |05 is applied to the cathode and grid of tube |26, and the amplified output across, the anode cathode circuit is supplied to a tube |30, which is preferably a Thyratron tube, such -as the type commercially designated #885. The tube is so negatively biased, by a negative bias potential obtained across a variable resistor I5 in the anode circuit of tube |26, that the tube is normally non-conductive. The Thyr-atron tube is kept just below ionization, or just below its ring point, and resistor H5 is adjusted for the proper bias. When Ithe travelling oscillator passes a timing point, the decreased anode current is accompanied by an increase in anode potential, and this lowers the negative bias of the Thyr-atron and causes it to lre. When the oscillator is midway of the pair of antennas, the energy supplied to the receiver is neutralized and .the Thyra.- tron negative bias rises to normal and the tube is deionized or deres As the oscillator passes midpoint and approaches the second antenna of the pair, the Thyratron again fires. This tube acts essentially as a sensitive trigger. Resistor and condenser ||9 act as a radio frequency iilter vfor any radio frequency passing rectifier |26, and resistor. also acts to limit any surge of grid current going back to tube |26.

The output of tube |30'is applied to the stepping coil |32 of a step relay, and it causes the armature or moving arm |34 of the relay to step upwardly each time that rtube |30 is fired. Arm |66 moves with arm |34, and its function is described later. A movable contact or plug |36 is plugged into that one of the contacts |138 which corresponds to'a timing point just preceding the 'terminal timing point of the race. With the present arrangement, the tube |30 isred once for each antenna or twice for each timing point, and the number of steps selected when plugging in the plug |36 should take this fact into account,

there being twice as many steps as |there are' timing points.

The clocl to be controlled by .the receiver is indicated at 16, and the eld coil thereof at 11. This really represents a clock group, for there may be more than one clock, all connected together, most.simply in parallel. Most frequently there will be one for the judges, and one or more for public display. The clock group is, for simplicity, frequently .treated and referred to herein as a clock, the group being supplied with alternating current from -a regular 11o-volt line,` and the current' supply is controlled by a starters switch 18. It will be understood that, in practice, the starting switch 18 controls the'supply of cur- I. rent to bus wires from which a plurality of clock .thus deenergizing relay coil trated in simplest form with a single Wave rectifier. The rectier is shunted by contacts |42 which are opened at the end of the race. 'Ihese contacts form part of a double coil lock-out relay, the companion coils of which are indicated at |44 and |46, coil |46 being a locking coil. 'I'he contacts |42 are shown open because they are normally open and are closed only during energization of coil |44.

The rectifier |40 is also shunted -by contacts |48. These contacts are controlled -by a relay coil |50, and contacts |48 are normally open when coil |50 is not energized. Relay |50 is a stick relay, it being provided with a pair of normally open contacts |152 arranged in series with coil |50. These contacts are shunted by anormally open switch |54 of the push-button type. At the beginning of a race, and before the race is actually Started, the button |54 1s pressed, thereby energizing coil |50, which, in turn, closes contacts |52 and contacts |48. The closing of contacts |52 keeps the coil energized, and this, in turn, keeps contacts |46 closed, thus shunting the rectifier |40. The circuit has lthus been made ready for l the start of the race, and when .the starting switch 18 is closed by the starter, the clock 'I6 is supplied with alternating current and is thereby started. Relay coll |50 also controls a pair of norm-ally closed contacts |56. When coil |50 is energized, the contacts |56 are opened, and they remain so at the start of and during most of the race. This deenergizes lock-out coil |46, and so permits coil |44 .to function if and when energized by the Thyratron and step relay circuit previously referred to. Coil |44, besides controlling the normally open contacts 42, also controls the normally closed contacts |58, the purpose of which is later described.

It was previously mentioned that plug |36 connected to relay coil |44 is plugged into that one of step relay contacts |38 corresponding to a. tim'- ing point preceding the terminal timing point. It will thus be seen that, as Thyratron tube |30 fires for the successive timing points, it merely steps up the step relay and does not energize coil |44, and, at the timing point preceding the terminal timing point, the Thyratron steps switch |34 as far as the contact receiving plug |86, thus preparing the way for energization of relay coil |44 when the Thyratron is fired the next time, that is, at the terminal timing point. When the Thyratron is next fired at the rst` antenna of the .final timing point, the relay coil |44 is energized. This causes closing of contacts |42, thus maintaining, for a brief additional time, the desired shunt around r'ectier |40. At the same time, it opens contacts |58, thereby opening the circuit through relay coil |50, and this, in turn, permits opening of contacts |48 and |52. Italso permits closing of contacts |56, thus energizing locking coil |46 from the direct current source |60. When the oscillator reaches the true timing point, and is midway between the antennas, the radio frequency energies supplied to the receiver neutralize one another and'the Thyratron delires,

|44 and opening contacts |42. short-circuited and instantly functions, so that the current supply to clockf'coil H is changed from alternating current ,to -direct current and the clock is stopped and frozen in position. Contacts |58 are closed" at the same time. but this is without consequence Ibecause contacts |52 and switch |54 are both open.

It has been mentioned that. at next to the The clock rectifier |40 is no longer y ing antennas.

Any later firing of the Thyratron, as when the oscillator passes the second antenna of the terminal pair, or should the oscillator continue its travel past another timing point beyond the terminal timing point, has nocifect on the clock, and the circuits remain in the terminal condition because of the influence of locking coil |46 which, when it is energized and has attracted the relay armature to itself, dominates the influence of coil |44, the latter being unable to pull the armature back. Of course', when manual pushbutton |54 is pressed at the beginning of the next race, the lock-out coil |46 is deenergized because of the Vopening of contacts |56 resulting from energization of relay coil |50.

The condenser |2| is connected across relay |44 in order to prevent chattering of the relay, but this condenser is not ymade -large enough to smooth outthe pulsating nature of the current in thelanode circuit of the Thyratron |30 resulting from the use of alternating current at the source |10. Alternating current is there used in order to insure instantaneous cut-off or dering of the Thyratron when the grid potential isl restored to normal, as at the timing point. It may be mentioned that direct current with a chopper may be used instead of alternating current, but the latter is so commonly' available that it is convenient to use the same..

Fig. 8 shows a modication of the left-hand part of Fig. 7, such as may be used when the energies from the leading and trailing antennas are to be combined after rectication. Referring to Fig. 8, the energy from onetransmission line is fed to a selective radio frequency ampliiier |12', while the energy-from the other transmission line` is fed to a similar radio frequency amplifier |14. With the circuit connected and arranged as .here shown, the amplier |12 should be connected to the leading antennas, and the amplifier |14 should be connected to the trail- The amplied radio frequency output is applied to the input of. tubes |16 and |18, by means of coupled tuned circuits |86, |82 and |84, |86. Tubes |16 and. |18 are similar to tube |26 of Fig. 7, that is, they may be of the type known com mercially'as #'15, which function not only as a diode rectifier but also, to amplify the -rectied energy. Condensers |13 and resistors |15 act as a radio frequency filter. Resistors |11 are in series with the diode rectiflers, and the rectified potentials to be amplified are developed thereacrcss and are applied to the grids, all as was previously described. The quantitative value of the potential may be varied bytaps '|9. The resistors |8| are merely stabilizing resistors, similar to resistor ||3 in Fig. '1. The rectied energies are combined bin phase opposition and are then coupled to a tape recorder |68 and a. Thyratron tube |90. The connection of the rectied outputs in lphase opposition is indicated by the anode resistors |92 and |94 which are connected to one another and to a .common anode potential supply lead |96. The Tryratron tube |90 corresponds to the tube |30 in Fig. '7, and the coil |98 corresponds to the stepping relay coil |32 in Fig. '1. The remainder of the circuit has not been redrawn but may beidentical with that shown in Fig. 7.

The bias potential on the grid of Thyratron |90 is made such that the tube is just below ionization. This bias may be regulated by the use of a special biasing battery and potentiometer, or the like, or, as in the present case, the plate current resistors |92and |94 may be made variable, and these may be 4so relatively adjusted as to obtain the desired bias, assuming, of course, that the bias needed is so small as not to disadvantageously affect the accuracy of response in the recorder |88. If any noticeable error appears in the recorder, then it is preferableto use a perfectly symmetrical push-pull arrange'- ment with equal resistors |92 and |94, andto ob'- tain the grid bias of the Thyratron by external biasing means. In operation, when the oscillator passes the leading antenna, there is a current loss through resistor |92 and a consequent fall in bias potential. 'I'he resulting change in bias causes firing of the Thyratron tube and consequentstepping of the step relay. -When the travelling' oscillator comes midway between the antennas, the potential drop across the resistors |92 and |94 is equalized and the Thyratron de'- iires. When the oscillator passes the second antenna, there is decreased current through resistor |94 and there is an increase in the negative bias of the Thyratron, thus preventing nring. With this arrangement, the Thyratron fires only once for each timing point. It fires ahead of the true timing point and stops iiring at the timing point.

The operation and control of the clock will be understood by recollecting the operation of the arrangement in Fig. 7, the only change being the use of half as many steps in the step relay;

'I'he firing of the Thyratron at the timing point before the last, brings the step relay into connection with plug |36, and prevents further operation of the step relay coil. The ring of the Thyratron at the first momentarily closes the clock rectifier .contacts |42 and opens the contacts |48. When the oscillator passes the true finish line midway between the antennas, the Thyratron deiires and contacts |42 are opened and the clock is stopped.

Reverting to Fig. 8, it will be understood that the resistor |83 and-condenser |85 form a filter for radio ferquency energy, and that resistor |83 also functions to prevent backward surge of grid current, all as was described in connection with resistance ||1 and condenser I9 in Fig. 7.

It isbelieved that the constructioniand operation, as well as ythe many advantages of my improved timing apparatus will be apparent from the foregoing detailed descriptiongthereof. At the beginning of the race, the horses are each supplied with a miniature transmitter of charantenna of the finish line' acteristic frequency. this being appropriately mounted in the saddle equipment. The plugs |36 of the various receiversare plugged in at the proper point, depending upon the length of the race. Connections |64 are similarly adjusted but to one less step. Push-buttons |54 are depressed, thus setting the various relays in desired manner and closing the shimting contacts |48. A switch, not shown in the drawings, is also closed to begin operation of the tape feeding motors of the various tape recorders. The starter, as a part of starting the race, closes switch 18, thus beginning operation of all of the clocks. As the horses pass the successive timing points, a record of their progress is made on their respectivetape recorders. The exact time of each horse. and their relative timing, may be determined from comparison of the tapes after the race has been completed. In the meantime, the clocks count off the timing ot the race, and the clock-stopping mechanism is inoperative as the horses pass the early timing points because of the stepping relay. At the terminal timing point, however, the shunt around the clock rectifier is opened, thus converting the current supplyjreaching the clock from alternating current to direct current, and this not only stops the clock but freezes it in position. As the successive horses pass-the finish line, their respective clocks are thus stopped.-

(Each clock may be a clock group, as previously explained.) The circuits remain in that condition due to the action of'lock-out coil |46.` Coil |46 holds the relay armature even if coil |44 is again energized. Yet coil |46 will not attract the amature away from coil |44 if coil |44 is already energized and is aready holding the armature. When coil I 44 is rst energized' by the` leading antenna just ahead of the finish line, thecoil |46 is deenergized because contact |56 is open. In other words. during most of the race, both coil |44 and coil 46 are ,deenergized The coil |44 isenergized, and attracts the relay armature, and only thereafter is coil |46 energized (by opening of contacts |56 followed by closing of contacts |56). Coil |46 cannot attract the armature because it is already drawn to coil |44. At the iinish line coil |44 is deenergized, and coil |46 attracts the armature and holds it thereafter. This condition is not changed until the start of the next race, when the push-button |54 is again depressed.

The oscillator and cells may be located at the saddle ofthe horse, or the oscillator, which may be made exceedingly tiny, may belocated at the head with the cells at thesaddle, or the oscillator and cells may be located at the saddle with an antenna or radiating means located at the head of the horse, if an antenna is to be used, though no antenna is needed. If it is desired to 'compensate for the distance between the oscillator at the saddle and the head of the horse, without attempting to produce the radiation at the head of the horse, the stationary antennas may be shifted relative to the timing point. In other words, the leading antenna distance may be made greater, and the trailing antenna distance may be made less by an amount equal to the average distance between the standardized saddle oscillator location and the nose of a horse. With other racing vehicles, say, autos, the antenna may be located at the forward end of the' vehicle, or the oscillator may be located a standardized distance back from the forward end, and the antennas may be compensated for that distance as above explained. The result f shifting the antennas may be considered as being a shift of the timing point by the desired amount, to deal with the location oi. the oscillator on the moving object, instead of dealing with the forward end of the object in its relation to the true timing point.

In order not to unduly complicate the drawing, I have not included therein the means for marking the beginning of the timing on the tape. 'This is preferably done by a circuit connected to the starters switch (see Fig. 1) so that the starters switch, when closed, not only starts the clocks, but also causes the stylus of the recorder .to be sharply displaced in order to make a starting mark on the moving tape. This is done by a circuit arranged in shunt with the regular stylus moving circuit, said auxiliary shunt circuit being energized only at the moment of closing of the starters switch and thereafter having vno further function.

I'he condenser |2| around relay |44 is not needed if the relay is designed to operate on pulsating current. l

It will be apparent that, while I have shown and described my invention in preferred forms, many changes and modiiications may be made in the circuits and structures disclosed without departing from the spirit of the invention defined in the following claims. In the claims, clock includes clock group. The statement that the antennas are equally spaced on each side oi.' the timing point includes the adjustment for distance between the oscillator and forward end of the moving object.

I claim:

1. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic radio frequency different from the others, an antenna mounted at a timing point to receive energy radiated from said oscillators, a plurality of receivers connected to said antenna and each selective for the characteristic radio frequency of one of the oscillators, a timing device connected to each receiver and responsive to the receiver output so as to be operated when the oscillator passes a timing point.

2. In a timing apparatus comprising a portable radio frequency oscillator, a pair of antennas mounted in equally spaced relation on opposite sides of a timing point to receive energy radiated from said oscillator, a receiver connected to said antennas and-so arranged as to combine the energies from the antennas in phase opposition, whereby the resultant energy is zero when the oscillator is at the timing point.

3. Timing apparatus comprising a portable radio frequency oscillator, a pair of antennas mounted in equally spaced relation on opposite sides of a timing point to receive energy radiated from said oscillator, a receiver connected to said antennas and so arranged as to combine the energies from the antennas in phase opposition, whereby the resultant energy is zero when the oscillator is at the timing point, and a timing device connected to the receiver and responsive to the receiver output so as to be operated when the oscillator passes a timing point.

4. In a race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic frequency different from the others, a pair of antennas mounted in equal- 5. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each Ahaving a characteristic frequency different from the others, a pair of antennas mounted in equally spaced relation on opposite sides of a timing point to receive energy radiated fromsaid oscillators,

, transmission line connecting said antennas, a rea plurality of receivers connected to said antennas and each so arranged as to combine the energies from the antennas in phase opposition, whereby the resultant energy is zero when the oscillator is at'the timing point, each of said receivers being selective for the characteristic frequency of one of the oscillators, a timing device connected to each receiver and responsive to the receiver output so as to be operated when the oscillator of respective characteristic frequency passes a timing point.

6. Timing apparatus comprising a portable radio frequency oscillator, a plurality of antennas distributed at spaced timing points around the path of travel to be followed by the oscillator, a

ceiver connected to said transmission line, a timing device, means responsive to the output of said receiver for stopping the timing device, and a discriminating means to make said stopping means effective solely when the oscillator passes a selected one ofthe timing points.

7. Timing apparatus comprising a portable radio frequency oscillator, a plurality of antennas distributed at spaced timing points around the path of travel to be followed bythe oscillator, a transmission line connecting said antennas, a receiver connected to said transmission line, a timing device connected to the receiver and responsive to the receiver output so as to be operated when the oscillator passes each timing point.

8. Timing apparatus comprising a portable radio frequencyoscillator, a plurality of antennas distributed at spaced timing points around the path of travel to be followed by the oscillator, a

transmission line connecting said antennas, a receiver connected to said transmission line, a rst -timing device connected-to the receiver and responsive to the receiver output at all of the timing points, a second timing device, means responsive to the output of saidreceiver for stopping the second timing device, and a discriminating means vto make said stopping means effective solely when the oscillator passes a selected one only of the timing points.

9. Race timing apparatus comprising a plurality of portable `radio frequency oscillators, each having a characteristic frequency different from the others, a plurality of antennas distributed at spaced timing points around the race track, a transmission line connecting said antennas, a plurality of receivers connected to said transmission line and each selective for the characteristic frequency of one of the oscillators, a timing device for each receiver, means responsive to said receiver for stopping the associated timing device, and a discriminating means to make said stopping means effective solely when the respective oscillator'passes a selected one of the timing the others, a plurality of antennas distributed at spaced timing points around the race track, a transmission line connecting said antennas, a plurality of receivers connected to said transmission line and Yeach selective for the characteristic frequency of one of the oscillators, a timing device connected to each receiver and responsive to the receiver output so as to be operated when the oscillator of respective characteristic frequency passes each timing point.

11. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic frequency different from the others, a plurality of antennas distributed at spaced timing points around the race track, a

transmission line connecting said antennas, a plu-- rality of receivers connected to said transmission line and each selective for the characteristic frequency of one of the oscillators, a first timing device connected to each receiver and responsive to the receiver output at all timing points, a second timing device for each receiver, means responsive to said receiver for stopping the second timing device, and a discriminating means to make said stopping means effective solely when the respectiveoscillator passes a selected one only of the timing points.

12. Timing apparatus comprising a portable radio frequency oscillator, a plurality of pairs of antennas distributed at spaced timing points around the path of travel to be followed by the oscillator, the antennas in each pair being in equally spaced relation leading andtrailing the timing point for that pair of antennas, a first 'transmission line connecting all of the leading antennas, and a second transmission line connecting all of the trailing antennas, a receiver vconnected to said transmission lines and so ari ranged as to combine the energies from the transaround the path of travel to be followed by the oscillator, the antennas in each pair beingl in equally spaced relation leading and trailing the timing point for that pair of antennas, a first transmission line `connecting all of the leading antennas, a second transmission l-ine connecting all of the trailing antennas, a receiver connected to said transmission lines 'and so arranged as to combine the energies from the transmission lines in phase opposition, whereby the resultant energy is zero when the oscillatorlis at the timing points, and a'timing device connected to the receiver and responsive to the receiver output so as to be operated when the oscillator passes each timing point.

14. Timing apparatus comprising a portable radio frequency oscillator, a plurality of pairs of antennas distributed at spaced timing points around the path of travel to be followed by the oscillator, the antennas in each pair being in equally spaced relation leadingand trailing the timing point for that pair of antennaspa first transmission line connecting all of .the leading antennas, a second transmission line connecting all of the trailingantennas, a receiver connected to said transmission lines and so arranged as to combine the energies from the transmission lines' receiver and responsive to the receiver output at all of the timing points, a second timing device, means responsive to said receiver for stopping the second timing device, yand a discriminating means to make said stopping means effective solely when the oscillator passes a selected one only of the timing points.

15. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic frequency diiferent from the others, a plurality of pairs of antennas distributed at spacedl timing points around the race track, the antennas in each pair being in equally spaced relation leading and trailing the timing point for that pair of antennas, a irst transmission line connecting all 'of the leading antennas, a second transmission line connecting all of the trailing antennas. a plurality of receivers connected to said transmission lines and so arranged as to combine the energies from the transmission lines in phase opposition, whereby the resultant energy is zero when the oscillator is at the timing points, each of said receivers be` ing selective for the characteristic frequency of one of the oscillators, a timing device for each receiver, means responsive to said receiver for stopping the timing device, and a discriminating means to make said stopping means effective solely when the respective oscillator passes a selected one of the timing points.

16. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic frequency different from the others, a plurality of pairs of antennas distributed at spaced timing points around the race track, the antennas in each pair being in equally spaced relation leading and trailing the timing point for that pair of antennas, a first transmission line connecting all of the leading antennas, a second transmission line connecting all of the trailing antennas, a plurality of receivers connected to said transmission lines and so arranged as to combine the energies from the transmission lines in phase opposition, whereby the resultant energy is zero when the oscillator is at the timing points, each of said receivers being selective for the characteristic frequency of one of the oscillators, and a timing device connected to each.receiver and responsive to the receiver output so as to be operated when the oscillator of respective characteristic frequency passes each timing point.

17. Race timing apparatus comprising a plurality of portable radio frequency oscillators, each having a characteristic frequency diiierent from the others, a plurality of pairs of antennas distributed at spaced timing points around the race track, the antennas in each pair being in equally spaced relation leading and trailing the timing point for that pair of antennas, a first transmission line connecting all of the leading antennas, a second transmission line connecting all of the trailing antennas, a plurality of receivers connected to said transmission lines and so arranged as to combine the energies from the transmission linesin phase opposition, whereby the resultant energy is zero when the oscillator is at the timing` points, each of said receivers being selective for the characteristic frequency .of one of the oscillators, a first) timing device connected to each receiver and responsive to the receiver output at alltiming points, a second timing device for each receiver, means responsive to said receiver for stopping the second timing device, and a discriminating means to make said stopping means eiective solely when the oscillator passes a selected one only of the timing points.

18. Timing apparatus comprising a portable radio frequency oscillator, a plurality of antennas distributed at spaced timing points around the path of travel to be followed by the oscillator, a transmission line connecting said antennas, a receiver connected to said transmission line, a timing device, a starting means to be used at the start of a run in order to start the timing device, a step relay connected to said receiver and functioning to step up as the oscillator passes the successive timing points until it passes the timing point preceding a desired terminal timing point, said step relay then functioning to so connect the receiver to a stopping means for the timing device in order to stop the timing device when the oscillator passes the terminal timing point.

19. Signalling apparatus for use with a moving object, said apparatus comprising means adapted to be mounted on said objectv for radiating radio frequency energy, spaced stationary antennas to receive energy radiated from said moving object, a receiver connected to said antennas and so arranged as to combine the energies from the antennas in phase opposition, and means functioning when subjected to zero resultant energy as the moving object passes midway between the antennas for thereupon controlling a desired mechanism.

GEORGE HENRY GORDON.