System and Method For Protecting Transmissions of Wireless Microphones Operating in Television Band White Space

Abstract

A wireless microphone system broadcasts a pilot tone at the designated ATSC pilot position in the TV Band channel being used by the wireless microphone system. The pilot tone is a readily detectable waveform transmitted in the ATSC pilot position. The pilot tone can be generated by any one of: a standalone pilot tone generator; a pilot tone generator incorporated into a wireless microphone receiver; or, a pilot tone generator incorporated into a wireless microphone.

1 . A method of determining whether a radio frequency channel is available for use, the method comprising:
 down-converting a radio frequency signal in the radio frequency channel to yield a down-converted signal;   processing the down-converted signal to generate an ordered plurality of bins;   selecting from the ordered plurality of bins a number of bins centered at a predetermined location of the radio frequency signal;   analyzing the selected bins to determine if an energy spike is present in any one of the selected bins; and   if an energy spike is not present in any one of the selected bins, declaring the radio frequency channel available for use; else   further processing the radio frequency signal to a baseband signal and analyzing the baseband signal in the time domain to determine if the baseband signal contains a sync signal.   
     
     
         2 . The method of  claim 1  wherein the radio frequency channel is a TV Band channel. 
     
     
         3 . The method of  claim 1  wherein the processing comprises performing a predetermined number of Fast Fourier Transforms (FFTs) of the down-converted signal and the ordered plurality of bins are generated by accumulating an energy into respective bins associated with the respective FFTs. 
     
     
         4 . The method of  claim 1  wherein the predetermined location is at a mandated location of an Advanced Television Systems Committee (ATSC) pilot in the radio frequency signal. 
     
     
         5 . The method of  claim 1  wherein the sync signal is a DTV field-sync. 
     
     
         6 . The method of  claim 1  wherein the sync signal is a DTV segment-sync 
     
     
         7 . A device, comprising:
 a tuner to tune to a channel and receive a signal;   a digitizer that digitizes the signal from the tuner to produce a digitized signal;   a transform in communication with the digitizer which transforms the digitized signal;   an analyzer which analyzes the transformed digitized signal to determine if the digitized signal contains an energy spike that exceeds a predetermined threshold and if an energy spike is not present, declaring the particular channel available for use, else further analyzing the digitized signal in the time domain to determine if the digitized signal contains a sync.   
     
     
         8 . The device of  claim 7  wherein the transform is a Fast Fourier Transform. 
     
     
         9 . The device of  claim 7  wherein the device is a TV Band device. 
     
     
         10 . The device of  claim 7  wherein the channel is a TV band channel. 
     
     
         11 . The device of  claim 7  wherein the sync is a DTV field-sync. 
     
     
         12 . The device of  claim 7  wherein the sync is a DTV segment-sync.