Monitoring of pal signal waveforms

Claim 2

In processing color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, each field interval in said four-field sequence being distinguishable from the other three thereof, a method of monitoring the waveform of said signals comprising the steps of: developing a plurality of signals having characteristics which differ from different fields in said four-field sequence; selectively passing one of said plurality of developed signals; controlling the actuation of a trigger pulse generator with the selectively passed signal so that trigger pulse generation is restricted to association with only a selected one of the fields in each four-field sequence; and using said triggering pulse to waveform a waveform display.

Claim 3

In apparatus for monitoring the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, each field interval in said four-field sequence being distinguIshable from the other three thereof, control apparatus comprising the combination of: means coupled to said signal course source for developing signals having characteristics which differ for different fields in said four-field sequence; means subject to actuation by an output of said signal developing means for generating a trigger pulse timed to occur just prior to the beginning of a field interval; a switch; and means for utilizing said switch to selectively control the actuation of said trigger pulse generating means by said developed signals in such manner that said trigger pulse generation is restricted to association with only a selected one of the fields in each four-field sequence.

Claim 4

In apparatus for monitoring the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, each field interval in said four-field sequence being distinguIshable from the other three thereof, control apparatus comprising the combination of: means coupled to said signal course source for developing signals having characteristics which differ for different fields in said four-field sequence; means subject to actuation by an output of said signal developing means for generating a trigger pulse timed to occur just prior to the beginning of a field interval; a switch; and means for utilizing said switch to selectively control the actuation of said trigger pulse generating means by said developed signals in such manner that said trigger pulse generation is restricted to association with only a selected one of the fields in each four-field sequence.

Claim 5

Control apparatus for use in monitoring the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, said control apparatus comprising the combination of: means responsive to said PAL signals for developing a first pair of oppositely-phased square waves having a frequency corresponding to one-fourth the field frequency of said PAL signals; means responsive to said PAL signals for developing a second pair of oppositely phased square waves also having a frequency corresponding to one-fourth the field frequency of said PAL signals, each wave of said second pair being effectively shifted in phase by one field interval relative to a corresponding one of said first pair; a switch; a trigger pulse generator; and means establishing control of the actuation of said trigger pulse generator by a selected one of said square waves so that said trigger pulse generation is restricted to association with only a selected one of the fields in each four-field sequence.

Claim 6

Control apparatus for use in monitoring the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, said control apparatus comprising the combination of: means responsive to said PAL signals for developing a first pair of oppositely-phased square waves having a frequency corresponding to one-fourth the field frequency of said PAL signals; means responsive to said PAL signals for developing a second pair of oppositely phased square waves also having a frequency corresponding to one-fourth the field frequency of said PAL signals, each wave of said second pair being effectively shifted in phase by one field interval relative to a corresponding one of said first pair; a switch; a trigger pulse generator; and means establishing control of the actuation of said trigger pulse generator by a selected one of said square waves so that said trigger pulse generation is restricted to association with only a selected one of the fields in each four-field sequence.

Claim 7

Control apparatus for use in conjunction with a waveform display devise to monitor the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, said control apparatus comprising the combination of: means responsive to synchronizing components of said PAL signals for developing a first pair of oppositely-phased square waves having a frequency corresponding to one-fourth the field frequency of said PAL signals; means responsive to synchronizing components of said PAL signals for developing a second pair of oppositely phased square waves also having a frequency corresponding to one-fourth the field frequency of said PAL signals, each wave of said second pair being effectively shifted in phase by one field interval relative to a corresponding one of said first pair; means responsive to signal characteristics unique to a particular one of the fields of said four-field sequence for detecting the occurrence of each field interval in said PAL signals exhibiting said unique signal characteristics; means responsive to the output of said detecting means for determining the sense of the developed square waves of said first and second pair; a trigger pulse generator; manual selective means for controlling the actuation of said trigger pulse generator in accordance with any selected one of said square waves to restrict said trigger pulse generation to association with any selected one of the fields in each four-field sequence; and means for applying said trigger pulse to said device to selectively establish a waveform display.

Claim 8

Control apparatus for use in conjunction with a waveform display devise to monitor the waveform of the output of a source of color television signals of the PAL type, the synchronizing and blanking components of said PAL signals being such that successive field intervals of said signals differ in accordance with a repeating four-field sequence, said control apparatus comprising the combination of: means responsive to synchronizing components of said PAL signals for developing a first pair of oppositely-phased square waves having a frequency corresponding to one-fourth the field frequency of said PAL signals; means responsive to synchronizing components of said PAL signals for developing a second pair of oppositely phased square waves also having a frequency corresponding to one-fourth the field frequency of said PAL signals, each wave of said second pair being effectively shifted in phase by one field interval relative to a corresponding one of said first pair; means responsive to signal characteristics unique to a particular one of the fields of said four-field sequence for detecting the occurrence of each field interval in said PAL signals exhibiting said unique signal characteristics; means responsive to the output of said detecting means for determining the sense of the developed square waves of said first and second pair; a trigger pulse generator; manual selective means for controlling the actuation of said trigger pulse generator in accordance with any selected one of said square waves to restrict said trigger pulse generation to association with any selected one of the fields in each four-field sequence; and means for applying said trigger pulse to said device to selectively establish a waveform display.

Claim 9

Apparatus in accordance with claim 4 wherein the first and second-named square wave developing means are respectively triggered by respective oppositely-phased square waves having a frequency corresponding to one-half the field frequency of said PAL signals; and wherein said apparatus includes meaNs for developing said half-field frequency waves under the control of field frequency waves derived from the synchronizing components of said PAL signals.

Claim 10

Apparatus in accordance with claim 5 wherein said manual selection means includes means for optionally controlling the actuation of said trigger pulse generator in accordance with said field frequency waves, and wherein said apparatus also includes: means for combining said half field frequency waves with one of the square waves of said first and second pair to develop a stairstep wave; and means for adding said stairstep wave to the PAL signals subject to display in the circumstance of field frequency wave control of said trigger pulse generator.