NTSCTV原理.docx

1、NTSCTV原理Chapter 1. NTSC IntroductionRaster Scan Deflection WaveformsFigure shows Horizontal & Vertical Sweep Voltage Waveforms, and their relative timing RelationshipsInterlace Raster ScanIllustration of scanning beam on CRT face during Interlace scan. Interlaced ScanIllustration of how Interlacing

2、is accompolished.Raster Scan Synchronization WaveformsNTSC/RS-170A, complete set of waveforms, including Composite Blanking. Note Color Subcarrier phasing (in red).Horizontal Sync ComplexIllustrating Front Porch, Sync Tip, Back Porch with Color Burst riding on it. The interval between the end of the

3、 sync tip & the start of the burst is sometimes refered to as the Breeze -way. Note also, the Burst Flag (D.C. Restore clamp).Vertical Sync RecoveryVertical sync recovery by Integration of composite sync waveform.So-called Hammerhead waveformNormally invisible waveform of the Vertical Interval, show

4、ing the relationship of the Horizontal sync Pulses; Pre-Equalization Pulses; Serration Pulses; Post-Equalization Pulses; Color Burst, etc.Sync SeperatorCircuit for the recovery of both, Horizontal Sync & Vertical Sync, as well as, Even/Odd Field Flag.Sync SeperatorSync Separator with Noise pulse sup

5、pression-used in terrestrial receivers & VTR/VCRs.Horizontal DeflectionHorizontal deflection circuit, showing Drive transistor, Damper diode, Deflection Coil, Resonating & linearizing Capacitors; with High Voltage Fly-back transformer (tuned to third harmonic of scanning frequency).Horiz Deflection

6、SequenceL & C Charge Discharge sequencing related to horizontal scan beam position.Numerical Relationships Phase Locked Loop (PLL)Broadcast Spectrum ShapingNTSC Broadcast signal uses Vestigial SideBand (VSB) transmission, with properly bandlimited I & Q chroma information. Note also, the aural carrier 4.5 MHz. In practice, this is inserted as a highlevel aural transmitter output at the transmitting antenna