Patent Application
20120169881
The present invention relates to electronic timing systems for athletic events, such as track, swimming and other racing event and sports event, and more particularly to electronic systems and methods for timing automatically athletic or other events using radio controlled starting and timing units and one or more video cameras.
Electronic systems and methods for timing athletic-events such as track or swimming performances are known in the art. One previous system is known as “Accutrack,” which is sometimes referred to as a photo finish record system that produces a time sequence set of photographs of contestants crossing a line. Generally with such a system, a sound activated switch located on or near the starter detects the firing of the starter's gun, horn or other sound device. The switch may be coupled to the recording system with a wire, or a flash generating and detecting system may be used in order to eliminate the wire connection between the sound detecting device and the recording system.
Such conventional systems typically have been characterized by high cost (such as including expensive cabling or radio links to quickly communicate the time of the start of a race from the starting location to the finish location), or else have inconvenient user interaces or human signaling or separate character recognition software or the like. What is needed are improved accurate, low cost, easy to use systems and methods for schools and other organizations that cannot afford currently available high end systems.
The present invention is directed to systems and methods that provide innovative and reduced cost fully automated timing for athletic or similar type events. With the present invention, radio-based starter and timer units, and a video camera and computer and associated software, fully automatic timing systems and methods are provided that are easy to use and that allow schools or other organizations to host a quality track meets, swimming events, etc., with accurate times and fast results.
In accordance with the present invention, the starter and timer units are radio controlled, so there is no need to wire the starter or point a timing device at the starter's pistol. This reduces the need for recalls due to difficult-to-aim timers missing the light from the starter's pistol. In addition, in preferred embodiments of the present invention, the starter and timer units provide built-in digital radio communication between the starting and timing officials. Everyone is ready when it is time to start the race due to the hardware semaphore system consisting of push buttons, lights, and sound, allowing officials at the start and at the timing station be in synchronized communication.
Also in accordance with the present invention, handshaking and clock synchronization are provided between the starter unit and the timer unit for accurate and convenient timing of events. Preferably, timing information is encoded in video frames from a camera for subsequent display and analysis on a capture computer. In preferred embodiments, after handshaking and clock synchronization, race start is detected by the starter unit, which then transmits the race start time to the timer unit, which uses the race start time and its own synchronized real time clock to determine elapsed race time for embedding into the video fields. Intuitive and easy to use buttons and lights allow the race officials to communicate wirelessly (via radios), so that sporting events may timed conveniently and accurately. Systems and methods in accordance with the present invention are video-based system preferably with accuracy to about 0.016 second and time reported in 1/1000 seconds. Optionally, video interpolation software may be utilized to provide more precise timing with conventional video systems.
Systems and methods in accordance with the present invention may be reliably triggered by a .22 or .32 caliber starting pistol or other sound implement with an acoustic sound detection circuit, so there is no special ammunition required. Alternatively, race/event starting may also be triggered by a normally open contact that is closed such as by button push.
In accordance with preferred embodiments, systems and methods preferably include intelligent radios for both the starter and timer units and software on a capture computer to capture and review videos. Finish line images of each race preferably are recorded every 1/60th of a second for photo finish results, which resolution may be increased optionally with video interpolation software. The race time is recorded (preferably encoded) on each frame of the video and is saved to a computer's hard drive. Playback of captured results is easy. Software preferably provides an easy to access file naming system for each heat or race event recorded. Optionally, event results may be transferred to event or meet management application software such as with a click of a mouse.
Accordingly, it is an object of the present invention to provide easy to use radio-based starter and timer units for starting athletic events and recording elapsed time on video frames of a camera near the finish line.
It is another object of the present invention to provide improved radio communications between the starter unit and the timer unit, preferably with improved handshaking.
It is yet another object of the present invention to provide improved timing of athletic events with synchronized clocks and transmission of event start from the starter unit to the timer unit to reduce latency concerns regarding the successful transmission of the race start to the timing unit and official.
It further is an object of the present invention to provide improved systems and methods for encoding timing information in video information, which may included encoded timing information in video frames and/or interpolated video frames.
Finally, it is an object of the present invention to provide improved systems and method for timing athletic events using conventional starting guns or other sound implements, with easy to use radio-based units for efficient communications between race officials and video cameras so that accurate timing systems may be utilized for schools and other organizations who could not previously afford such systems due to their high cost or complexity.
The above objects and other advantages of the present invention will become more apparent by describing in detail the preferred embodiments of the present invention with reference to the attached drawings in which:
The present invention will be described in greater detail with reference to certain preferred and alternative embodiments. As described below, refinements and substitutions of the various embodiments are possible based on the principles and teachings herein.
In accordance with preferred embodiments of the present invention, radio controlled, video-based systems and methods for fully automatic timing of athletic events are provided. Exemplary preferred embodiments of the present invention will now be described.
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As will be described in greater detail in connection with
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In accordance with embodiments of the present invention, systems and methods are provided for fully automatic timing for track, swimming or similar racing or athletic events such as boating, driving, cycling, skiing, etc. Starter unit 2 and time unit 4 communicate in a wireless manner, and there is no need to wire starter unit 2. The radio communications may remove the need for an event official to hang out of a press box window or stand on a ladder to raise above the crowd to point a device at the starter. The built-in communications between starter and timing officials and visual indicators of system state status may remove the need to wave flags or hands to indicate that the event officials are ready to proceed with the start of the event. In accordance with the present invention more reliable starts are provided, and there is a reduced need to restart the event because of a poorly aimed device or lack of bright light from a starting device or false premature triggering such as from a spectator's flash camera.
In accordance with preferred embodiments of the present invention, a more affordable video-based system may be provided, for example, with a resolution of about 0.017 seconds, time reported in 1/1000 seconds. Starter unit 2 may be sounded actuated so as to work with, for example, .22 or .32 caliber starting pistols, with no special ammunition required.
Additional operational aspects of preferred embodiments of the present invention will now be described.
Starter unit 2, which is located proximate to the starting official, detects the start of the race when the starting pistol is fired. Starter unit 2 sends a signal to timer unit 4, which starts the race clock. Timer unit 4 is connected to computer 16 and video camera 6. Timer unit 4 receives a live video feed from video camera 6, preferably time stamps each frame of the video signal and passes the video signal on to computer 16 for storage and review. It is important that the starter and timing officials communicate before the start of each race to indicate that they are both ready for the race to begin. Conventionally, this has been accomplished by hand waving or flags. In accordance with preferred embodiments of the present invention, a fully automatic timing system is provided in which such important communication between event officials is integrated into the system. “Ready” buttons and green lights (i.e., ready buttons/lights 1 and 9 of
More particularly, communication between event officials and systems of the present invention is done with push buttons, lights, and sound, which indicate the starting and timing officials' readiness to start the race. There preferably are two light/button combinations on each unit, the green light/ready button and the red light/stop button. The officials communicate with each other by pressing the buttons on their respective starter or timer unit.
The green/ready button is used by either official to signal to the other that they are ready to start the race. The red/stop button is used by either official to signal to the other that they are not ready to start the race, to recall the race or to reset the race clock. The lights and sounds on the units convey the message and indicate the current state of the system, preferred embodiments of which will be further described.
In the “idle state,” both lights on the units are off and waiting for an official to signal that they are ready to start the race.
The “are you ready state” is indicated by a green blinking light. This occurs when one official presses the green ready button to signal that they are ready to start the race. The unit will beep twice every 5 seconds on the unit that needs to acknowledge.
The “ready to start race state” is indicated by a steady green light on both units, which occurs when both officials have signaled their readiness to start the race by depressing the ready button.
The “race in progress state” is indicated by steady green and red lights on both units.
The “not ready signal” is indicated by a flashing red light and busy tone.
The “radios not communicating signal” is indicated by a flashing red light and a rapid busy tone. In such event, the start of the race needs to be postponed until communication between the units is established or a backup timer is in place and ready.
As previously described, each of starter unit 2 and timer unit 4 preferably have two buttons, green ready and red stop (see, e.g., buttons/lights 1, 3, 9 and 11 of
In preferred embodiments, each of starter unit 2 and timer unit 4 are powered off as follows. Each of starter unit 2 and timer unit 4 are powered off by pressing the red button and holding it for a predetermined length of time, such as for 4 seconds. The unit preferably will beep a predetermined number of time, such as 4 times, and then turn off. The radios within each unit will automatically turn off after a period of inactivity. Starter unit 2 will turn off after being in the idle state for a predetermined length of time, such as 10 minutes, and timer unit 4 will will turn off after a predetermined length of time, such as 30 minutes, of the race clock being reset, a button pushed or a light on. Other time out periods and/or sequences are used in alternative embodiments.
The radio units of starter unit 2 and timer unit 4 communicate over a preset radio channel. In some cases, the preselected channel may interfere with other radio operations in the area and the radios may not be able to communicate properly with each other. To verify that the units are communicating, an exemplary operational sequence is as follows. Place the units within a short distance (such as 1-400 feet) of each other, preferably with no obstacles in between the two units. If the units are off, the red buttons on both units may be pressed and a check is made whether the battery charge is acceptable on each unit. A press of the green button on either unit will initiate an attempt to establish radio communications. The green ready light preferably will blink green on both units if the units are communicating properly. A press of the red button on both units to will turn off the lights and reset the units. The red stop light will blink and a rapid busy signal will sound if the unit does not detect the other radio or if the radios are otherwise not communicating properly. If the units are not communicating properly, the units are powered off and a different radio channel is selected. Preferably each unit has a channel selector switch (see, e.g., channel selector switches 5 and 13 of
With the radios communicating properly, the units may be setup for the start of an event. Starter unit 2 preferably is positioned on the starting line next to the starting official. The radio 10 unit of starter unit 2 should be located a short distance, such as 1 to 2 feet, from the starting pistol or other sound implement when the pistol or other implement is in its up or ready to fire position. The sound implement can be attached to a starter stand or a tripod, or be held in the starting official's other hand, or attached to the starters arm holding the starting device.
Timer unit 4 preferably is attached to timing/capture computer 16 as previously described. Video camera 6 preferably is located near the finish line and is connected or otherwise in communication with timer unit 4 such as with a standard video cable (as previously described, wireless or other links are used in alternative embodiments to accomplish this connection without a cable, provided that suitable control is provided over the line of site and any interference that may be present). Timer unit 4 acquires the video signal from finish line video camera 6 and passes it to computer 16 optionally through digital converter 12 (see
Starting a race or other event may proceed as follows. Once the runners or other participants are ready, the starting and timing officials must check with each other to establish that they are both ready to start the race. The starting official typically will initiate this exchange by pressing the green ready button on starter unit 2. This sends a “are you ready?” signal via radio communication to timer unit 4. The green lights on both starter unit 2 and timer unit 4 blink, indicating that the starting official is ready and is waiting for the timing official to acknowledge the signal. The receiver unit, in this example timer unit 4, preferably will also beep twice every 5 seconds using speaker 15 (see
In preferred embodiments, the starting official has a predetermined length of time, such as 5 minutes, to start the race once the units are in a ready-to-start state and the ready light turns steady green. The race clock in preferred embodiments starts when the starter fires the starting pistol or other sound implement. Once the race clock starts, the red and green lights (e.g., switches/lights 1, 3, 9 and 11 of
In preferred embodiments, both the starting official and the timing official may abort the process at any time before the starting pistol is fired by pressing the red stop button (e.g., buttons/lights 3 and 11 in
Also in preferred embodiments, one of the officials has a predetermined length of time, such as 5 minutes, to respond after the other official presses the green button, otherwise the units will time out. When an official presses the green ready button, the green lights preferably blink on both units. If the other official does not acknowledge the signal by pressing a button within the predetermined time, e.g., 5 minutes, both units will give off the “not ready” signal (i.e., flashing red light and busy tone) and then return to the idle state. In such event, one of the officials must reinitialize the “are you ready?” signal before continuing. Likewise, the starting official has the predetermined time, such as 5 minutes, to start the race once the ready light turns solid green. Preferably the green light will blink rapidly on one or both units and one or both units will start beeping for the last, e.g., 30 seconds of the time period to indicate that the system is about to abort. This is a signal that the starting official only has a few seconds to start the race with re-initializing. In preferred embodiments, the starting official is recommended to abort the process by pressing the red stop button. This helps ensure that the starting official has enough time to adequately start the race and that the timing official is ready.
In a typical race or other athletic event, it is important to give either the starting official or the timing official the capability to abort or recall the event, such as in the occurrence of an unfair or “false” start by one or more participants. After the race starts, the starting official may press the red stop button (e.g., button/light 3 of timer unit 2 in
In preferred embodiments, the race clock will start once the units are in the ready to start race state and starter unit 2 detects the vibrating sound waves from the starting pistol or other sound implement. Starter unit 2 may mistakenly pick up the vibration of other sounds or from starter unit 2 being bumped and inadvertently start the race clock. The units will beep and the green and red lights will be on when this occurs. The starting official can press the stop button within 20 seconds if he/she suspects that this has occurred and the units will go back to the ready to start race state. Otherwise, the timing official will need to press the stop button to reset both units.
In preferred embodiments, if a unit is unable to send a signal to the other unit when a green button is pressed, the red light will flash along with a rapid busy or other distinctive sound. This is similar to the busy signal that occurs when an official presses the red button to abort the race. The distinction is that the tones are played differently, such as closer together, and the signal usually occurs immediately after pressing a button. The starting official may test the radio communication whenever the starting official moves to a new starting position on the track or course and before the next race or event. This may be done, as previously described, with a press of the green go button (see, button/light 1 of
Referring now to
At step 20, both starter unit 2 and timer unit 4 are in an idle state, preferably with no lights on, and still more preferably in a low power state. At step 22, a determination is made of whether either the starting or timing official activated a green button on the respective starter unit 2 or timer unit 4. If yes, the method proceeds to step 24; if no, the method returns to step 20 to await a green button push. At step 24, a signal is transmitted to the other unit (from radio 1 to radio 2 in
At step 34, a signal is transmitted to radio 1, and an attempt is made to synchronize the clocks a predetermined number of times, such as 8 times. As will be described in greater detail elsewhere herein, starter unit 2 and timer unit 4 both include real time clocks (RTCs) that are synchronized in step 34. At step 36, a determination is made whether the RTCs of the two units have been successfully synchronized; if yes, then the method proceeds to step 38; if no, then the method proceeds to step 40. At step 38, the units are now in a ready state awaiting start of the race or other event. Step 38 preferably is indicated by solid green lights on both units, which may be accompanied by a sound from the speakers indicative of the ready state.
After step 38 of
At step 48, a signal is transmitted to timer unit 4 from starter unit 2. In preferred embodiments, an attempt is made to transmit, based on the synchronized RTCs, the start time of the race to timer unit 4 a predetermined number of times, such as 8 times. At step 50, it is determined if the transmission of the race start time was successful; if successful, this is signaled from timer unit 4 back to starter unit 2, and then the method proceeds to step 52; if not successful, then the method proceeds to step 40. At step 52, the method is in the race running state, which preferably is indicated by solid red and green lights on both units. As also described elsewhere herein, timer unit 4 encodes the time since the race/event start on frames of the video information received from camera 6, which are then output to computer 16, for subsequent display, under control of software running on computer 16, of video images with displayed race times included on the displayed video frames. At step 54, it is determined if the timing official pressed the red button, indicative of the ending of the race or other event (at which point the method proceeds to step 40). If the timing official has not pressed the red button, the method returns to the race running state of step 52. As previously described, at an early point in the race, the starting official also may hit the red button to recall the race, at which time the method would proceed to step 40 (the starting official recalling the race, such as in the event of a false start, is not expressly shown in
More specifically, video camera 16 records the runners, swimmers, etc., as they cross the finish line. Timer unit 4 encodes the race time on each frame of the video and the video and times are displayed on computer 16 under software control. The computer operator can capture video through the race or can start capturing the video when the first participant approaches the finish line. Only the relevant video needs to be captured and stored on the computer 16's hard drive. The video is available for review at the end of each race. The review official may advance the video to the frame that shows the runner's torso on or over the finish line to determine the athlete's time.
Preferably, the software running on computer 16 may exchange data with other meet management software applications, including Hy-Tek Meet Manager, Sydex's Track Gold, Easy Meet Manager, TrackMate and Apple Raceberry Jam. In such embodiments, the software preferably displays the list of seeded athletes in the event. The review official preferably clicks on the runner's name or lane in the list and the time is recorded automatically. When all runners are recorded, the results can be transferred to a desired meet management application program with a click of a button. The software preferably can work with one, two or three computers. One computer is sufficient when you have adequate time between races for one person to review the video and record the times. If a meet management programs is utilized, then preferably two or three computers are networked together. With three computers, one computer may be dedicated to capturing the video, one for playback and review and one for scoring with the meet management application. As soon as a race is recorded and saved on the capture computer, the video file preferably appears on a list or queue of captured videos on the review computer. The capture computer is free to record the next race while the review official reviews the video on the playback computer. The operator of the meet management application typically spends most of the time entering results from the field events into the meet management application. The finish line judge preferably notifies the meet management operator when all times from a race are recorded and saved. The meet management operator preferably loads the times into the meet management application with one mouse click and the race is scored. These timing computers in general can be located in any desired location around the track or other venue. The one requirement is that the radio units are able to communicate. As previously described, line of sight is best, but the radio units preferably are capable of finding a path around some obstructions. In most setups, the computers are located either at the base of the video camera or in a press box. In a typical high school setting, where the press box is on top of the stadium and the finish line is next to the stands, around 200-300 ft of cable typically may be required to connect the video camera to the computer in the press box.
Referring now to
Circuit block 60 generally refers to a video circuit, preferably only utilized in timer unit 4. Input J2 represents a video input, such as from camera 16, the input signal of which is coupled to U10, which preferably is a LTC 6241 dual CMOS op amp, believed to be commercially available from Linear Technology Corporation, the data sheet and other technical information from Linear Technology are hereby incorporated by reference. Incoming video preferably is AC coupled to the input (U10.3) of an op amp in U10 preferably configured as a voltage follower with an average voltage of Vsleep/2. The follower output, Unclmp, preferably is AC coupled through C23 to Clmp. V(Clmp) is periodically back-porch sampled by analog switch, U11. That sampled voltage is compared with a reference voltage, VSbk. by the op-amp Q10b. Since U11 only conducts during back-porch time the circuit acts to drive the back-porch voltage to equal that of Vsbk. VSbk (and VSwh, which is discussed later) are set by a voltage divider, R29, R30, and R28. U11 preferably consists of a commercially-available ADG779, CMOS, SPDT switch/2:1 Mux, the data sheet and commercially available technical information for which are hereby incorporated by reference.
V(Clmp) is fed to another voltage follower, U12A to produce a buffered output. V(Buffered) is fed to one side of the analog switch, U13. The alternate input to U13 is the output of U14 which, by alternating between VSbk and VSwh, generates the bit pattern to be inserted according to V(WFM). As will be appreciated based on other disclosure herein, such bit pattern may be used to encode elapsed race time into (preferably) each frame of video information captured by camera 16. U13, according to V(INSERT), selects between the clamped and buffered video signal and the bit pattern generated by U14. Under control of CPU U3 (see block 62), which also incorporates the real time clock discussed elsewhere herein, the elapsed race time may be encoded into the video signal. The output of U13, V(Muxed), preferably is applied to a 2× amplifier consisting of U12B (U12 also consists of a commercially-available LTC 6221 dual op amp, which also may be from Linear Technology) and the associated components to produce the signal gain and offset needed to back-terminate the output.
Sync information preferably is extracted from the unclamped signal by U4, a special-purpose integrated circuit that extracts frame, field, H sync and back porch information from the signal. In preferred embodiments, U4 consists of a LMH1981 Multi Format Video Sync Separator from National Semiconductor, the data sheets and commercially technical information for which are hereby incorporated by reference.
By way of further background information, which is known to those of skill in the art, back porch typically refers to a portion in each scan line of a video signal between the end (rising edge) of the horizontal sync pulse and the start of active video. Such portion of a video scan line may be used to restore the black level (300 mV.) reference in analog video. In signal processing terms, it compensates for the fall time and settling time following the sync pulse. In color TV systems such as PAL and NTSC, the back porch also may include the colorburst signal. Such general video concepts are known to those of skill in the art.
More generally, circuit block 60 illustrates exemplary circuitry for inputting a video signal from camera 16 into timer unit 4, and encoding the race time into frames of the video signal under control of CPU U3. In alternative embodiments, other circuits and components are used.
Power generation and management will now be further described. Preferably, the power source in preferred embodiments consist of standard rechargeable or non-rechargeable batteries, such as 3 or a different number of AA size battery cells. Preferably, shunts are provided on the PCB (at J4) that allow either directly powering the unit (starter unit 2 or timer unit 4) from the batteries, or from a switcher connected to the batteries. See circuit 74 and U15 for an exemplary switcher circuit. Switcher circuit preferably is a LTC3534—7V, 500 mA Synchronous Buck-Boost DC/DC Converter (the data sheets and commercially available technical information for which are hereby incorporated by reference), which serves to buck or boost the voltage to provide a switcher output voltage SW Out (which may be tested at test point J16). Alternatively, if the switcher is not used, the minimum cell voltage may be, for example, 1.25V, meaning that non-rechargeable alkaline or lithium cells preferably should be used. If the switcher is used, preferably starter unit 2 and timer unit 4 will tolerate cell voltages down to about 1V. Switcher selection preferably is accomplished through changing the positions of the shunts located at connector J4 of circuit block 64. If the shunts bridge J4.1-2 and J4.3-4, the switcher acts to buck or boost the battery voltage as appropriate. When the shunts bridge J4.2-3 and J4.4-5, the battery drives the series regulators, U7 and U9 (circuits 66 and 68) directly. Preferably, the output voltage provided by U7 and U9 is nominally 3.3V. To extend battery life, the source voltage applied to U7 (which regulates VSleep) preferably is switched off in standby mode, while U9 always supplies Vcc to the processor and the start-up circuit (see circuit block 62).
As will be appreciated by those of skill in the art, circuit block 72 generally refers to a radio unit used in both starter unit 2 and timer unit 4.
Referring now to circuit block 70, an exemplary trigger arrangement used in preferred embodiments will now be described. Circuit block 70 preferably only exists in starter unit 2. Starter unit 2 preferably is triggerable in two ways. The first is through an acoustic mechanism. A small loudspeaker connected via J6 of circuit block 62 is used as a microphone which will generate a pulse in response to the sound from a starting gun or other sound implement. This pulse preferably is AC coupled to Q6, which has a quiescent current of less than 10 uA. In addition to the AC coupling through C37, additional high frequency sensitivity is provided by C34, located in the emitter circuit of Q6. In the absence of an input signal Q10 typically has less than 100 mV of forward bias. However, based on the diode equation, the emitter current increases by a factor of 10 for each 60 mV of additional forward bias. Thus, and without being bound by theory, a 60 mV signal is large enough typically to cause Q10 to conduct. This activates the positive feedback loop formed by the path through Q11, causing V(Out) to drop from about 3V down to less than a volt, discharging C39 to below the threshold voltage needed to trigger an interrupt at P0.2 of CPU U3 of circuit block 62 (the signaling to CPU U3 of the start of the race preferably is by interrupt to CPU U3, which is detected on an interrupt line of CPU U3. What is important is that a circuit is provided that can detect the sound impulse from the starter's gun or other sound implement and generate a signal that can be coupled to CPU U3 so as to signal the start of the race and carry out corresponding operations as described elsewhere herein.
The second mechanism of triggering an interrupt or other start indicative signal to CPU U3 is through recognizing a contact closure. Preferably, Q8 functions as what is known as a Colpitts oscillator, using one winding of T1 and C31 and C32 as a tank circuit. Q8 preferably drives the tank circuit with relatively narrow current pulses, causing Q5 to C34 to ground every cycle. However, if a low resistance is applied to J21.1-2, oscillation stops, causing C30 to rise almost to V(VSleep). That rising voltage is differentiated by C38 and R72, turning on Q11. Positive feedback through Q10 trips the one-shot similarly to the way it is triggered in the first case. Note also that when the oscillator stops, Q5 is conducting only very slightly, causing the junction of R56 and R65 to rise almost to V(VSleep), causing the sensitivity of the acoustic trigger to increase. If the contact closure is not desired, the oscillator should be stopped. Therefore the connection to J21 should be through a shorting jack to ensure that the acoustic input behaves properly when contact closure detection is not wanted. What is important is that a circuit be provided that allows a contact closure, such as via a push button switch or the like, that serves to signal to CPU U3 that the race has started.
Also as will be appreciated by those of skill in the art, Vbat S is generated by U6, which preferably is a dual MOSFET circuit, commercially available and known in the art as a FDC6318A, the data sheets and commercially available information for which is hereby incorporated by reference. Side 1 of U6 preferably serves to control speaker attached to J6, which side 2 is used to generate V Bat S (switched battery voltage). V Bat S preferably is used via U7 to generate VSleep, while Vbat is used by U9 to generate Vcc. As will be appreciated by those of skill in the art, having two supply voltages, VSleep and Vcc enable a full power operating mode and a lower power operating mode in which only selective components are powered, thereby enabling reduced power consumption. U7 and U9 preferably are LP3990, which are commercially available components, data sheets and commercially available information for which are hereby incorporated by reference. A further exemplary description is that such low power mode may be detected by CPU U3 via detecting button pushes (see S1 and S2 of circuit block 62, which illustrate exemplary buttons/LEDS used for buttons/lights 1, 3, 9, and 11 of
Op amp 1 of U17 of circuit block 62 is an exemplary circuit (LTC6241 such as previously described) that provides a reference voltage that may be used as an analog input to CPU U3, which can read the resistive divider-generated reference voltage to determine the state of the batteries such as described elsewhere herein. As will be appreciated by those of skill in the art, CPU U3 may have pins programmed to receive analog voltages, which may be input to an analog to digital converter in CPU U3 that enables the battery voltage to be monitored (controlled by P 2, 3 and read by P 2, 2 of CPU U3).
As will be appreciated, the circuits and circuit blocks of
Further aspects of hand shaking and clock synchronization used in preferred embodiments of the present invention will now be further described.
The radio system used in preferred embodiments (described elsewhere herein) for automatically timing race events consists of two units: starter unit 2 and timer unit 4. It is important that the real time clocks (RTC's) of these two units be synchronized. Preferred embodiments include a “handshaking” process describe earlier to indicate that both the starter and timing officials are ready to start the race. During this process, starter unit 2 and timer unit 4 preferably have their real time clocks (RTC) synchronized.
Synchronization preferably starts when timer unit 4 sends a start synchronization command to starter unit 2. Starter unit 2 preferably returns an acknowledgment and immediately sets its RTC to a number that will reach zero when sufficient time has lapsed for timer unit 4 to receive the acknowledgment signal. Timer unit 4 preferably sets its RTC to zero when it receives the starter's acknowledgment signal. The synchronization between the timer unit 4 and starter unit 2 is then verified to ensure they are within an acceptable tolerance of, preferably, +−3 micro seconds.
Without being limited to particular numeric values, in preferred embodiments, the time necessary for the transmission between the units and the RTC's initialization has been empirically characterized for the preferred radio units and in the exemplary embodiments is 191/32768 seconds. This number resulted from field trials of the radios separated by as little as 2 feet and as much as 300 feet. The variance from these tests averages 100 micro seconds with a standard deviation of a fifth of that number. The accuracy required for fully automated timing generally is considered around 10 milliseconds.
In preferred embodiments, the synchronization process is repeated if there are any transmission failures or error in the verification. If the units cannot be synchronized after a predetermined number of tries (8 in the preferred embodiment) an alarm is raised at both units and the starting official knows not to start the race. If the RTCs in the units are synchronized, the starting official is given the “ready” signal to start the race. At the start of the race, starter unit 2 transmits the start time to timer unit 4. Error detection information preferably is included in the message so timer unit 4 can detect bad data and request a retransmission if needed. Seconds are available for this transmission since the shortest race commonly found is the indoor track meets for example is 60 meters in about six seconds and the 100 meters in about 10 seconds.
Preferred embodiments of the present invention have advantages over a method that only transmits a signal corresponding with the start instant when the race starts. This is so because the signal could receive interference and would need to be retransmitted. This would cause an error in the race time.
Although the invention has been described in conjunction with specific preferred and other embodiments, it is evident that many substitutions, alternatives and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims. For example, it should be understood that, in accordance with the various alternative embodiments described herein, various systems, and uses and methods based on such systems, may be obtained. The various refinements and alternative and additional features also described may be combined to provide additional advantageous combinations and the like in accordance with the present invention. Also as will be understood by those skilled in the art based on the foregoing description, various aspects of the preferred embodiments may be used in various subcombinations to achieve at least certain of the benefits and attributes described herein, and such subcombinations also are within the scope of the present invention. All such refinements, enhancements and further uses of the present invention are within the scope of the present invention.
