Local event broadcast system
BACKGROUND OF THE INVENTION 
     There are a great many local events at which it would be extremely desirable to broadcast information concerning the event to the spectators or participants thereof. This function is usually performed by a public address system, often in conjunction with an illuminated display sign. Although this form of information transmission system is thought to be adequate, it should be noted that at many sporting events the spectators carry portable radios to receive the commentary and play by play description broadcast by the community radio media. Obviously many spectators desire more specific information than that provided by the public address system. 
     Further, there are many events at which many activities are occurring over a wide area and within the same time frame. For example, at golf tournaments, gymnastic or track and field meets, regattas, political conventions, industrial shows, auto races, parades, or the like, it is impossible to apprise the spectators or participants of information of general interest, or to broadcast information pertaining to a particular event to the immediate vicinity of the event. The resulting lack of information diminishes the pleasure of the spectators and adversely affects the performance of the participants. 
     It is known in the prior art to provide locally broadcast informational radio programs, in museums and the like, for the edification of the spectators therein. In these systems the signals are all of the same frequency, and the listener-spectator must select the program only by changing location. That is, the listener has no control over the program being heard. Also, the program material is recorded, and could not be applied to a live event. 
     SUMMARY OF THE INVENTION 
     The present invention generally comprises a local event broadcast system in which pertinent programmatic material is provided to spectators interested in specific activities occurring within the local event. The broadcast system includes a central control mobile unit which coordinates incoming information concerning the event, and which produces program material relating to various facets of the event. The program material is transmitted as a plurality of programs to a plurality of radio relay chains, the radio relays being advantageously placed so that the program material coincides with the activities occurring in the vicinity of each relay station. 
     The system also includes a plurality of tunable radio receivers, each to be carried by one of the spectators. Associated with each relay station is a low power local radio transmitter which transmits the pertinent program material to the local spectators. The spectators may tune their individual radio receivers to the particular program which pertains to the activity they are viewing, so that the commentary they receive relates directly to the activity of the immediate area. 
    
    
     THE DRAWING 
     The FIGURE is a block diagram representation of the local event broadcast system of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the accompanying Figure, the present invention generally comprises a limited broadcast system which provides coverage of a particular event to the spectators in attendance at the event. It includes a central mobile unit 11 which houses the main program studio of the system. In the central mobile studio live activity reports and pretaped program material are gathered, edited, screened, and rebroadcast. 
     The program material is radio broadcast to a plurality of radio relay units 12, 13, 19, 21, 29, 30, 31, etc., which are disposed about the area in which the event is occurring. For example, in the instance of a golf tournament the radio relay units would be disposed about the golf course so that maximum coverage of the area would be obtained. The relay units are battery powered, and broadcast at a maximum radiated power of 100 milliwatts. Due to the low power output of the relay units they may use the standard citizen band without interfering with the broadcasts of local CB radios. 
     The radio relay units receive a signal at a first frequency and repeat it at a second frequency. For example, the central mobile unit broadcasts to the relay units 12 and 19 at a frequency f 1 , and these units in turn repeat the signal at the frequency f 2  which is received by the relay units 13 and 21, respectively. At the same time a second program may be broadcast to the relay unit 29 at a frequency f 3 . The second program pertains to the activities occurring in the area in which the relay units 29, 30, and 31 are disposed. The unit 29 broadcasts to the relay unit 30 at a frequency f 4 , and the relay unit 30 broadcasts to the unit 31 at a frequency different from the previous mentioned frequencies, which unit 31 may in turn rebroadcast to additional relay units as shown. 
     Associated with each relay unit is a local transmitter which transmits the audio portion of the signal at low power to the tunable receivers in the immediate area of the local transmitter. Local transmitters 14, 16, 22, and 23 are associated with relay units 12, 13, 19, and 21 respectively. The local transmitters transmit at frequency A on the standard AM radio band, radiating 100 milliwatts and therefor covering a rather small area. Only those spectators in the immediate area of the local transmitters could receive the program material, which pertains to the event they are watching. 
     The local transmitters 33, 34, and 36 which are associated with the relay chain 29-31 all transmit at a frequency B on the standard AM radio band. To return to the example of the golf tournament, these relay units and local transmitters may be disposed about the final hole of the tournament, broadcasting program material which pertains particularly to the action occurring at the final hole. Those spectators in that vicinity could tune their receivers 37-39 to the frequency B to receive the special programming relating to the event taking place before their eyes. The general programming broadcast on frequency A could therefor be excluded by those individuals at the final hole. It is within the scope of the invention to provide a plurality of relay chains each carrying unique programming to separate areas where sub-activities of the general event are occurring. 
     The live portions of the program material originate from remote units associated with site transmitters 27 and 28. These units would include on the scene reporters to provide pertinent commentary, and broadcast at low power on the AM or CB band to the central mobile unit. 
     The tunable broadcast receivers are battery powered, and are provided with earplug type earphones and no speakers. In this manner those spectators and participants who do not wish to hear the program commentary will not be subjected to it.