Direct Digital Encoding and Radio Frequency Modulation for Broadcast Television Applications

Abstract

A digital audio encoder, digital video conditioner, and a digital modulator are described for producing a television broadcast signal at a desired channel frequency range. Left and right audio channel signals are digitized and encoded according to a stereo standard and then combined to form a stereo audio signal. A second audio programming channel signal may be included. A video input can be digitized and conditioned to form a digital video channel. The stereo audio signal can be placed directly at a desired channel frequency by frequency modulation without the need for using an intermediate frequency. The digital video channel can be placed at a desired frequency by amplitude modulation. The digital and audio channels can be digitally combined to create a television transmission signal at a desired frequency and according to a desired standard.

1 . A computer program product for producing a NTSC television signal and residing on a computer readable medium having a plurality of instructions stored thereon which, when executed by a processor, cause that processor to:
 digitize and encode left and right audio channels according to a BTSC stereo standard so as to produce a combined audio signal;   extract a stereo pilot signal from a broadcast compatible video signal;   place the combined audio signal directly at a desired final carrier frequency by frequency modulation without the use of an intermediate frequency signal;   place the video signal at a desired video carrier frequency by amplitude modulation;   combine the audio and video signals to create a combined digital signal suitable for transmission through a transmission medium;   
       convert the combined digital signal to an analog NTSC format signal; and 
       provide the NTSC format signal to at least one anti-aliasing filter. 
     
     
         2 . The computer program product of  claim 1 , further comprising instructions to provide the NTSC signal to at least one line amplifier. 
     
     
         3 . The computer program product of  claim 1 , further comprising instructions to digitize and encode a SAP audio channel according to the stereo standard as part of the combined audio channel. 
     
     
         4 . The computer program product of  claim 1 , further comprising instructions to transmit the NTSC signal through a transmission medium. 
     
     
         5 . A method of producing a NTSC television broadcast signal with a television broadcast signal system, comprising:
 with a digital video conditioner, extracting a stereo pilot signal from a broadcast compatible video signal;   with a digital stereo encoder, digitizing and encoding left and right audio channels according to the BTSC stereo audio standard, wherein a combined audio channel results;   with a digital modulator, placing the combined audio channel directly at a desired final channel carrier frequency by frequency modulation without the need for use of a signal of intermediate frequency;   with the digital modulator, placing the video signal at a desired video channel carrier frequency by amplitude modulation;   with the digital modulator, combining the audio and video signals to create a combined digital signal on a transmission channel;   converting the combined digital signal to a NTSC analog format signal; and   providing the NTSC analog format signal to at least one anti-aliasing filter prior to transmission.   
     
     
         6 . The method of  claim 5 , further comprising providing the NTSC analog format signal to at least one line amplifier. 
     
     
         7 . The method of  claim 5 , further comprising digitizing and encoding a SAP audio channel according to the stereo standard as part of the combined audio channel.