Patent ID: 7770297

Claim:
An electronically actuated first-down marking system for use in sporting activities executed on a pre-defined playing field, said first-down marking system comprising: first and second identification marking assemblies removably positioned on a first sideline of the playing field; third and fourth identification marking assemblies removably positioned on a second sideline of the playing field and oppositely seated of said first and second identification marking assemblies respectively; means for determining a distance between said first and second identification marking assemblies such that a game official can accurately measure ten yards between said first and second identification marking assemblies; means for aligning said first and second identification marking assemblies with said third and fourth identification marking assemblies respectively such that said second and fourth identification marking assemblies and said first and third identification marking assemblies are horizontally disposed along a single plane and on opposite sides of the playing field; and means for determining whether a mobile game ball has penetrated a first down plane defined by said second and fourth identification marking assemblies such that the official easily determines whether a first down has been achieved; wherein said distance determining means comprises a tuned frequency signal generating circuit housed within said first identification marking assembly; a first transceiver electrically coupled to said tuned frequency signal generating circuit, said first transceiver transmitting a first output signal generated by said tuned frequency signal generating circuit; a sensor housed within said second identification marking assembly; a second transceiver housed within said second identification marking assembly, said sensor being calibrated for generating a second output signal when said first output signal is detected as an authorized signal having a frequency within a pre-determined range, said second transceiver transmitting said second output signal to said first transceiver; a transducer; a processor electrically coupled to said transducer; and a memory electrically coupled to said processor and including software instructions for causing said first identification marking assembly to determine whether said first and second identification marking assemblies are ten yards apart, said software instructions executing a control logic algorithm including the steps of a. determining a total time interval lapsed between transmitting said first output signal to receiving said second output signal, b. multiplying said total time interval with the speed of light for obtaining a first value, c. comparing said first value with a second value wherein said second value equals ten yards, and d. if said first and second values are equal, causing said transducer to emit an audible signal for a pre-determined time period.