I'm working on extracting color information from an NTSC signal. The color information is encoded with quadrature multiplexing using dsb-sc. I want to demodulate the signal but it requires a carrier that is in phase with the transmitter. The signal does include a color burst which should be used to sync the local oscillator.
My approach is this: Make a high pass filter to eliminate the luma information, leaving me with mostly chroma information. Pass this through a very high Q IIR filter tuned to the carrier frequency. The output of the high Q filter will resonate long enough to be used to demodulate the chroma information. My problem is: how to I design a high pass filter that will only output positive frequency? Another approach I thought of was to use the fast convolution method (FFT filtering) but instead of multiplying against a filter just setting the bins of the frequencies I want to take out to 0. Not sure if that would actually work. I've seen lost of abstracts of papers that talk about quadrature filters but not sure if they are worth the money. -Daniel ____________________________________________________________________________________ 8:00? 8:25? 8:40? Find a flick in no time with the Yahoo! Search movie showtime shortcut. http://tools.search.yahoo.com/shortcuts/#news _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
