Complementary pre-emphasis and de-emphasis circuits for a video signal transfer channel
AssigneeBASF SE
InventorCaljon H. Strobele
Life of this patent
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Abstract
Complementary circuits for pre-emphasis and de-emphasis of video luminance signals, the circuits permitting an improved signal-to-noise ratio in a video signal transfer channel. The video signal has separate frequency- and amplitude-sensitive portions as well as a linear gain portion, thereby providing a fixed gain up to a predetermined lower frequency, a fixed response between this frequency and a variable upper frequency breakpoint, and an amplitude-dependent gain above the upper frequency breakpoint. De-emphasis is performed by a circuit also having separate frequency- and amplitude-sensitive portions and a linear gain portion, and which may be readily matched to the pre-emphasis circuit.
Claims22
In a wide band signal transfer system including a wide band signal transfer channel which is subject to unwanted noise across the wide band, pre-emphasis means for increasing, prior to introduction of said signal into said channel in pre-emphasized form, the amplitude of higher-frequency wide band signal components relative to lower-frequency wide band signal components without overdriving of the transfer channel, said pre-emphasis means comprising:
- input connections for receiving a signal having a wide band of frequencies within a predetermined amplitude range;
- means coupled to said input connections for subjecting said wide band signal to a predetermined linear gain;
- further means coupled to said input connections for subjecting said wide band signal to a non-linear gain, said non-linear gain being a direct function of the frequency and a switched function of the amplitude of the high frequency components of said wide band signal;
- and
- means coupled on their input side with said linear gain means and also with said non-linear gain means to supply at their output side a signal representing a linear combining of the input signals, said output signal being the pre-emphasized wide band signal.
In a wide band signal transfer system including a wide band signal transfer channel which is subject to unwanted noise across the wide band, pre-emphasis means for increasing, prior to introduction of said signal into said channel in pre-emphasized form, the amplitude of higher-frequency wide band signal components relative to lower-frequency wide band signal components without overdriving of the transfer channel and de-emphasis means connected to the far end of said channel for de-emphasizing the pre-emphasized wide band signal and supplying at an output said wide band signal substantially free of said unwanted noise, said de-emphasis means comprising:
- input connections for receiving said pre-emphasized wide band signal;
- means coupled to said input connections for subjecting the pre-emphasized wide band signal from said connections to a linear gain;
- further means coupled to said input connections and including a frequency dependent gain portion comprising a series-connected resistance-capacitance network for providing a gain which is a direct function of frequency, and also including a switched gain portion passing only the peak portions of the pre-emphasized wide band signal which exceed a predetermined magnitude;
- other connections for combining the signals from said linear gain means and said further means;
- and
- network means coupled to said other connections for subjecting the signal from said other connections to an inverse frequency dependent gain, and then passing said signal to said output.
Dependencies are inferred from the claim text.