AUSTRALIAN RULES FOOTBALL GOAL POST CONTACT DETERMINATION This innovation patent application is a divisional of Innovation Patent No. 2013100500 filed 13 April 2013 and the entire contents of that Innovation Patent and its specification are 5 incorporated herein by this cross reference. That Innovation patent is associated with Provisional Patent Application No. 2012902416 and the entire contents of the provisional patent specification are incorporated herein by this cross reference. This invention relates to enabling the determination whether or not a contact of a football with 10 a goal post has occurred, In Australian Rules football, if the football has been kicked by a player and the ball touches a goal post, a goal is not scored even if the ball has crossed the goal line between the two spaced goal posts (but a 'behind' or point is scored). Another rule of the game provides that if 15 the kicked football touches one of the outermost secondary or 'behind' posts without having first bounced, a point or behind is not scored even if the ball passes between that behind post and the nearer spaced goal post - rather the ball is deemed to have been kicked out of bounds 'on the full' and a penalty or 'free kick' is awarded to the opposing team. If the kicked ball has bounced and then touches the behind post, there is no score even if the ball passes 20 between that behind post and then next adjacent goal post - the ball is considered to have passed out of bounds and is thrown by an officiating umpire back into the playing field. In all of these possible situations, an error made by an officiating goal umpire in deciding whether or not the ball has touched the post can lead to an incorrect score being awarded or 25 perhaps a failure to award a score when the team was entitled to be so awarded. Such errors in scoring arising from errors of officiating umpires can change the course of the football game and even alter the final outcome of the game. There have been in the past decisions made by officiating umpires which have sometimes been clearly incorrect when the incident has been closely examined from images captured by a television broadcaster replaying the 30 incident in slow motion and from different viewing positions. At other times even such replays of video sequences can still leave the issue undecided but nevertheless controversial. It is an object of the present invention to provide a method and apparatus for enabling determination with greater accuracy whether a football, during play of a football game, has I -.
touched a post defining one side of the goal zone or a behind post defining one side of the secondary scoring zone. According to the present invention in a first aspect there is provided a method of enabling 5 determination whether a football, during play of an Australian Rules-Football game, has touched a post defining one side boundary of the goal zone, the method including the steps of: providing a sound vibration detector in contact with the post so that sound vibrations produced by substantially any impact or significant momentary contact of the football with the post during play of the football game will be registered by the sound vibration detector, 10 generating a contact signal by the sound vibration detector or in response to operation of the sound vibration detector upon the occurrence of an impact or momentary contact of the football with the post, transmitting signals generated by or in response to operation of the sound vibration detector to a storage means and storing them in the storage means as sound vibration data 15 signals, capturing and storing video images of the football game during play of the game including images of the football in motion (including in flight, and bouncing or rolling along the ground, and being carried by a player participating in the game), displaying for viewing by an observer the video images from a time period in the game 20 which included an incident of interest involving the football being in proximity to the post, and, in close synchronism with the display of the video images, manifesting the sound vibration information embodied in the stored sound vibration data signals in a manner enabling the observer to compare the synchronicity of any manifested sound vibration information with the displayed images of the football in closest proximity to the post and 25 thereby determine if the football has touched the post. Using this method involving capturing and displaying video images of the incident with a closely synchronised manifestation of the captured sound vibration information, the contact, or absence of contact, of the football with the post can be determined with greater certainty 30 than by observing the video images alone. Throughout this specification including the claims, references to "sound" occurring or produced or arising or travelling in or on, or ambient to, a football goalpost includes sound 2 vibrations at frequencies in the audible spectrum and also includes sound vibrations at frequencies in the inaudible spectrum. In one possible embodiment, the sound vibration detector comprises a contact microphone 5 mounted by the post and in close contact therewith so that the contact microphone preferentially detects sound vibrations within the post. For example, the contact microphone may comprise a contact condenser microphone mounted onto and in close contact with the surface of the post, 10 Preferably, the contact signal comprises an analogue signal representing the sound vibration detected and the method includes the steps of: converting the analogue contact signal to digital data representing the sound vibrations detected, and filtering the digital sound vibration data signals to enhance discrimination of sound is vibrations arising from contact of the football with the post from other or ambiguous sourced sound vibrations detected, the filtering being selected from Fourier filtering, Butterworth filtering, and other digital filtering, Preferably the manifestation of the sound vibration information embodied in the stored sound 20 vibration data signals is selected from: generating an audio output of the stored sound vibration data, the audio output comprising a processed manifestation of the stored sound vibration data, the processing comprising at least one of the processes of amplification, filtering, and frequency shifting; and creating and displaying a visible representation of the stored sound vibration data, the 25 visible representation being selected from * displaying a trace of the sound vibration signal with time comprising one axis of the trace and signal magnitude on an orthogonal axis, and a a visible indication whether the captured sound vibration data has satisfied predetermined criteria indicative of the football having contacted the post. 30 In one possible embodiment, there are at least two sound vibration detectors mounted in or on the post at different longitudinal positions along the length of the post, the two detectors being mounted in or on the structural body of the post and being separated along its length whereby the time interval between detection of the particular sound vibration by the two spaced 3 detectors provides information about the location of the football contact along the length of the post relative to the locations of the detectors, and the method may including computing from the time interval and displaying for the observer information about the deduced location of the football contact with the post. 5 According to the present invention in a second aspect there is provided an apparatus for enabling determination whether a football, during play of an Australian Rules Football game, has touched a post defining one side boundary of the goal zone, the apparatus including: at least one sound vibration detector provided in contact with the post so that sound 10 vibration produced by substantially any impact or significant momentary contact of the football with the post during play of the football game will be registered by the sound vibration detector, a signal generator operative to generate a contact signal upon the occurrence of an impact or momentary contact of the football with the post when registered by the sound vibration is detector, a storage means operative to receive signals generated by or in response to operation of the sound vibration detector and to store them as sound vibration data signals, video apparatus operative to capture and store video images of the football game during play of the game including images of the football in motion (including in flight, and bouncing 20 or rolling along the ground, and being carried by a player participating in the game) during play of the football game, display means operative to display for viewing by an observer the video images from a time period in the game which included an incident of interest involving the football being in proximity to the post, and sound vibration manifesting means operative to manifest the sound vibration information 25 embodied in the sound vibration data signals stored in the storage means in close synchronism with the display of video images by the display whereby the observer can compare the synchronicity of sound vibration information manifested with the images of the football presented by the display means including images of the football when in closest proximity to the post, thereby enabling determination if the football touched the post during play of the 30 football game. The present invention in this second aspect enables the observer operating or using or monitoring or watching the apparatus or system in operation to compare the synchronicity and the characteristics of manifested sound vibration information with the displayed images of the 4 football moving in closest proximity to the post and thereby the observer can determine if the football has touched the post. Further aspects of the method and apparatus of the present invention will be described with 5 reference to the accompanying drawings which schematically illustrate some aspects of possible apparatus utilising the invention. Fig, 1 illustrates a football goal post or behind post with at least one sound vibration detector which generates a signal and a transmitter which relays the signal to a remote receiver for 1o storage, processing and manifestation. Fig. 2 illustrates an apparatus receiving sound vibration data signals from the post(s) and for data processing, data storage, and providing signals for sound vibration manifestation. 15 In the following descriptions of possible and preferred features of apparatus and methods according to the invention, references to the drawings will be made where helpful, but the invention is not limited to anything shown in or described with reference to the drawings. In one possible system the manifestation of the sound vibration information embodied in the 20 stored sound vibration data signals comprises generating an audio output of the stored sound vibration data, That is, the stored sound vibration data signals are used to generate by a speaker or the like an audible sound, The audible output may be substantially unmodified captured sound vibration information, apart from being amplified. However preferably the stored sound vibration data is first processed by filtering so as to substantially attenuate or 25 remove sound vibration or vibration propagating in the vicinity, particularly in the post where there will be such sounds and vibrations that are not characteristic of the sound vibration encountered upon a football contacting the post. The sound vibration characteristics of a football contacting the post can be empirically determined enabling the filtering parameters to be defined so as to enhance discrimination of the sound vibration arising from a ball-post 30 contact e.g. by the "sound validity verification" module in Fig. 2, The processor in Fig. 2 also shows a "video generator" module responsive to the "sound validity verification" module and operative to generate for display an indication whether the validity verification module has determined a strong, moderate, or weak correlation between the characteristics of the actual sound vibration detected and the empirically determined expected characteristics of a ball 5 post contact. For example, if there is a strong correlation indicating near certainty of a ball post contact, a positive indicator in the video display can be generated (e.g. the word "YES", or a green coloured sound vibration trace) with a moderate correlation, the word "POSSIBLE" and/or amber coloured sound vibration trace may be generated, and with a 5 weak correlation the word "NO" and/or red coloured sound vibration trace may be generated. Likewise suitable amplification can be provided to enhance discrimination. Another form of processing may comprise frequency shifting of the detected sound vibration. For example if the detected sound vibration is in a part of the inaudible spectrum or perhaps in 10 a part of the audible spectrum more difficult to discriminate, the sound vibration arising from the ball-post contact may be detected, recorded and also frequency shifted so that when replayed through the audible output it can be more readily discriminated. If replayed at a slower speed (like a slow motion video replay) the sound vibration may be frequency shifted to ensure the audible sound is in the human hearing frequency spectrum. 15 Alternatively, or in addition, the manifestation of the sound vibration information embodied in the stored data signals may include creating and displaying for viewing by the observer a visible representation of the stored sound vibration data. In one particular embodiment for example, the visible representation may comprise displaying for viewing the sound vibration 20 data such as by displaying a trace of the sound vibration signal, or oscillographh", with time comprising one axis of the trace, normally the horizontal axis, and signal magnitude on an orthogonal axis (vertical axis preferably - this is shown schematically at the bottom of the video display in Fig, 2), In Australian patent specification No. 199952942 (patent No. 753622) in the name of Allan Plaskett (hereinafter referred to 'Plaskett') there is described in 25 detail methods and apparatus for converting a detected sound arising from a cricket ball touching a cricket bat and displaying the sound data captured, for example a trace on a screen or monitor of the sound signal. The same types of sound signal capture and processing described in Plaskett can be used with any necessary modifications given the different nature and sound vibration characteristics in the field of the present invention. The contents of 30 Plaskett are incorporated herein by this cross reference for the purpose of providing disclosure of apparatus for implementing certain aspects of the present system, particularly sound vibration signal processing and manifestation. 6 Fig. 2 also schematically illustrates there may be a "synchronisation" between the video processing and the sound vibration processor so the output video display includes any necessary adjustments for time shifts between video frame capture (effectively instantaneous) and sound vibration detection and capture. In particular, if the time of travel of the sound 5 vibration in the post from the ball-post contact point to the detector can be significant at the video frame capture rates in use, some time shifting of the sound vibration manifestation relative to the video display (particularly in a slow motion video replay) can provides the adjustment necessary for assessment of synchronicity of the sound vibration generation and the ball-post contact. 10 As an alternative (or in addition) to displaying a trace of the sound vibration signal, the visible representation of the stored sound vibration data may comprise a visible indicator whether the captured sound vibration data has satisfied pre-determined criteria indicative of the football having contacted the post. For example the sound vibration spectral characteristics or 15 'signature' of a football touching the post may be predetermined and the processing system may test detected sound vibrations to discriminate as legitimate sound vibrations arising from a ball-post contact from those sound vibrations that do not have those same characteristics or signature. If the remaining sound vibrations that satisfy the characteristics or signature specified fall within a time window coincident with video images captured for the football 20 moving in close proximity to the post, a visible indicator may be provided to affirm that a legitimate contact signature or characteristic has been detected. The time window for example may be defined by an operator selecting and inputting (using conventional peripherals (mouse, keyboard, etc.) of the video processor) start and finish points for a sequence of captured video image frames during which the ball is seen to be moving in close 25 vicinity of the post. Although the sound vibration detector may be located elsewhere so as to the operative to detect sound vibrations arising from ball-post contacts, it is most preferred that the sound vibration detector is located by mounting it in or on the post for detecting sound vibration 30 transmissions in or along the post arising from the relevant contact. The sound vibration detectors can be any suitable form such as piezoelectric transducers or other sound vibration detecting microphones or the like mounted in or on the post so as to detect and generate signals upon detecting sound vibration vibrations in the post. Such vibrations can arise from many sources including ambient noise, contact of players with the post, vibrations in the post 7 transmitted from the ground, etc. Because there are many sources of sound vibration, sometimes very loud sound vibration, filtering of frequencies that would not characterise the ball-post contact sought would be desirably performed. Also if desired, sound vibration cancellation technology may be used to capture sound vibration information from a vicinity of 5 the post, but not arising from a ball-post contact, with such background sound vibration data being electronically 'subtracted' from the sound vibration captured by the detector associated with the post. Such sound cancelling technology is known for example in hearing protective equipment used by workers in noisy environments. Filtering may include sound vibration volume "filtering" by seeking a sound vibration discernable above the volume of background 10 noise (which can be substantially constant in the short interval, perhaps 0.1 to 0.2 seconds, in which a ball-post contact sound vibration is being sought) - e.g. an average sound vibration volume in the target time interval can be calculated to define an envelope, and a short sound vibration signal of a volume outside that envelope can indicate the ball-post contact, 15 In one particular working embodiment of the invention, the or each sound vibration detector comprises a sound vibration detecting microphone of the kind known as a contact microphone which is mounted by the post and in close contact therewith so that it detects sound vibration substantially only within the post. In a particular preferred embodiment, the contact microphone is a contact condenser microphone which is mounted in close contact onto the 20 surface of the post. Such a microphone may be mounted onto the surface of the post in any convenient way such as by adhesive tape, whether two-sided tape disposed between the contact microphone and/or an adhesive tape or other band over the outside of the contact microphone holding it intimately onto the surface of the post. Contact microphones can be in the form of elongated strips having a length of about 20cm and, in use, the longitudinal 25 dimension can be vertical and can be mounted so it intimately contacts the surface of the post along its entire length, The contact microphone picks up the vibrations from the surface to which it is attached and substantially only from that surface so that ambient noise has very little or negligible effect on the signal output. 30 Suitable types of contact condenser microphones are ones produced by C.T. Audio (see www.c-ducer.com) and known as "C-ducer tape microphones". These are microphones that are primarily used for acoustical musical instrument amplification. For example, the contact condenser microphones can be mounted on the back of the soundboard of a piano for highly selectively detecting sound vibration, and for generating audio signals, from the associated 8 musical instrument exclusively with negligible detection of sound vibration from other instruments, singers, resonances within the venue, or audience. The C-ducer microphones are claimed to have a very wide frequency response, as wide as 0.1Hz to MHz compared to the normally quoted human audible frequency spectrum or range from about 20Hz to about 5 20KHz. It will be seen that such contact microphones can detect and signal sound vibration from well below the human audible spectrum and also well above the human audible spectrum. Particular contact condenser microphones available from C-T Audio Marketing Inc. that may be suitable include for example the model "CP2/8" C-ducer tape microphone having a frequency response of 25Hz to 50KHz so that it will detect and signal sound 10 vibration above the human audible frequency spectrum. (Note that this product is supplied with a pre-amplifier that limits its frequency response, so omitting to use the pre-amp can broaden the frequency response for the present use.) The microphone mounted in or on the post can be powered in any convenient way, e.g. by is battery or by power drawn from the signal line running from the microphone over which the output audio or sound vibration signal is passed. Such powering of microphones is known as "phantom power". The sound vibration signal output of the microphone may be an analogue signal containing 20 the frequency and amplitude information for the detected sound vibration in the post. This analogue output signal may be processed by a preamplifier located in proximity to the microphone, e.g. also mounted on the post. The preamplifier if desirable may restrict the frequency response range transmitted, e.g. to minimise induced noise and interference, but still if desired retaining sound vibration of frequencies above and or below the human audible 25 frequency spectrum. The balanced analogue output signal may be transmitted in any conventional way to the storage means, e.g. by RF signal or by wire. The analogue signal is preferably fed to an A/D converter for the further processing and storage in the storage means as sound vibration data 30 signals. Preferably the digital sound vibration data output from the A/D converter is filtered by any suitable digital filtering system so as to enhance discrimination of sound vibration from contact of the ball with the post from other or ambiguous detected sound vibration in or on or ambient to the post. The filtering for example may comprise Fourier filtering to enhance the more useful parts of the detected sound vibration spectrum and reduce noise in 9 the sound vibration data. Fourier filtering can lead to an artefact effect in the filtered signal leading up to the band of particular interest, so possibly a more useful or clearer filtering may comprise Butterworth filtering. In any event, the processed sound vibration data when manifested can be very substantially enhanced to enable clearer detection of sound vibration 5 arising from contact of the football with the post and discrimination of that sound vibration from sound vibration from all other potential sources. In one possible embodiment, there are at least two sound vibration detectors mounted in or on the post at different longitudinal positions along the length of the post (Fig. 1). Goal posts are 10 usually provided with protective padding along the lower part of its height to lessen risk of injury to a player colliding with the post and, with such posts, at least one detector may be mounted in or on the padding so as to detect ball-post contact involving the padding and at least one detector is mounted in or on the structural body of the post (e.g. metal, timber, plastics, ceramic, composite, or other structural material). 15 By providing two (or more ) detectors mounted in or on the stmuctural body of the post and separated lengthwise, the time interval(s) between detection of the particular sound vibration by the respective spaced detectors provides information about the location of the ball contact along the length of the post. Therefore the apparatus may have processing means (e.g. that 20 labelled "contact height algorithm" in Fig, 2) which computes from the time interval between the detection of the sound vibration by the two spaced detectors an approximate location of the ball-post contact. For example, one detector may by located at or in proximity to the lowest part of the post and the other located at or in proximity to the highest point of the post whereby the computation of the contact location along the major part of the length of the post 25 between the two detectors can be achieved by utilizing the times of detection by the two detectors of the particular sound vibration arising from a ball-post contact travelling within the post. For example, sound vibration travels in aluminium at somewhat over 6000 metres per second, so that sound vibration will travel the length of a six metre high post made of aluminium in about one millisecond. Arrival time differentials of much less than one 30 millisecond can be detected whereby the approximate position of the source of the sound vibration detected by the two detectors can be determined from the time interval between the two detector signals. For example, if the two detectors detect a sound vibration from a ball post contact substantially simultaneously, the contact of the ball with the post is substantially mid-way between the two detectors. If the top most detector first detects the sound vibration 10 and the bottom most detects the sound vibration one millisecond later, the contact will have been very close to the top detector. Other materials from which posts are manufactured will have different sound vibration propagation speeds and this can be incorporated into the programming. 5 In another embodiment there may be a plurality of detectors spaced along substantially the length of the post at pre-determined spaced locations. The amplitudes of the sound vibration detected at each detector can vary depending on the distance of the detector from the source of the sound vibration. This can arise from attenuation of the sound vibration as it travels in [0 the material of the post. The system therefore can include computation from the detected signal amplitudes at the plurality of detectors an indication of the approximate location of the contact of the ball with the post. With this amplitude utilisation, the system is believed to require calibration because variations in the sensitivity of the variety of detectors and variations in the sound vibration transmission parameters of the post will affect the detected 15 amplitudes. Also the sound vibration coupling between the posts and the mounting of each detector may have a bearing on the sensitivity of the detector to the sound vibrations travelling within the post and hence the amplitude of the detected sound vibration. The calibration may comprise generating test contacts of an article, particularly a football, with the post at various locations along its length and measuring the detected sound vibration 20 amplitudes at each of the plurality of detectors. Using the known locations of the test contacts of the football with the post, the system can calculate weightings or adjustments in a computational algorithm for relating the relative sound vibration amplitudes detected to the contact locations known in the calibration process. 25 In practical use, the indication of the deduced or calculated location of the ball contact where this is determined from detected sound vibration amplitudes and/or from time intervals between multiple detections by multiple detectors on the one post, that indication of calculated location is preferably displayed for the observer. The system is preferably operative to thereby enable the observer to compare the displayed computed or deduced 30 location of the ball contact with the displayed video images in the relevant time period which includes the suspected ball-post contact, By generating (by the "video display simulation generator" in Figure 2) and by providing a display of the calculated location of the ball contact, eg by an artificial highlight or glint or pointer or icon superimposed on an image of the post approximating the computed contact location (see the "calculated height indicator" I I icon in Fig, 2), any significant inconsistency between the approximate location of the ball contact observable in the video images and the location deduced or computed from the detected sound vibration signals can be apparent. This can enable the observer to eliminate spurious determinations of ball-post contacts due solely to a coincidental substantial 5 synchronicity of a candidate sound vibration transmission within the post and a video image of the football passing the post. For example, if the video image shows the football moving in close proximity to the post towards its upper end whereas the sound vibration detectors and associated processing system detect and compute an approximate position of the source of a detected candidate sound vibration as, say, one metre above the ground along the height of the 1o post, the candidate sound vibration is readily discriminated from one that would have arisen from an actual contact of the ball with the post 5-6 meters above the ground. In patent specification 013 2457674 in the name of Allan Plaskett there is described a system using at least four microphones to determine a location of an impact between a cricket ball 15 and a cricket bat and then generating an icon presented on a visual display representing the calculated location of the sound vibration producing impact. That system in the Plaskett specification is adapted for use with fixed cameras so that the generation and presentation of the icon can be superimposed on replayed video signals from the fixed camera field of view. In the present invention, video capturing cameras are likely to be moving and capturing video 20 images from multiple directions so that the moving football is visible from at least one of the captured video sequences. In the present invention therefore the indication of the computer football contact location is preferable on a simulated image of the post, e.g. presented in the visual display alongside the video images (see the "post simulation" image in Fig, 2). The Plaskett specification GB 2457674 nevertheless gives information illustrating how the 25 calculated football contact position can be determined and visually presented in the present invention. It will be appreciated that various modifications and variations of the method an apparatus as described herein can be devised without departing from the spirit and scope of the invention 30 as defined in the following claims. 12