Vertical reset genereator circuit

A method of generating a vertical reset pulse within a video system comprising the steps of:

• a. receiving a composite video signal including synchronization pulses, wherein the synchronization pulses include equalizing pulses and serration pulses each having a first level and a second level;
• b. building up a level of charge across a storage element during the first level of the equalizing pulses and the serration pulses;
• c. discharging the level of charge across the storage element during the second level of the equalizing pulses and the serration pulses;
• d. activating a vertical reset signal when the level of charge reaches a first threshold level;
• and
• e. deactivating the vertical reset signal when the level of charge reaches a second threshold level, wherein the second threshold level is different than the first threshold level.

A method of generating a vertical reset pulse representative of the presence of serration pulses within a composite video signal, comprising the steps of:

• a. receiving a composite video signal including equalizing pulses and serration pulses, wherein both the equalizing pulse and the serration pulses have a high level and a low level;
• b. separating the equalizing pulses and serration pulses from the composite video signal;
• c. charging a voltage level stored across a storage element during the low level of the equalizing pulses and the serration pulses;
• d. discharging the voltage level stored across the storage element during the high level of the equalizing pulses and the serration pulses;
• e. determining when the voltage level stored across the storage element reaches a first threshold level;
• f. activating a vertical reset pulse when the voltage level stored across the storage element reaches the first threshold level, wherein the voltage level stored across the storage element reaches the first threshold level within a first serration pulse after a series of equalizing pulses;
• g. determining when the voltage level stored across the storage element reaches a second threshold level;
• and
• h. deactivating the vertical reset pulse when the voltage level stored across the storage element reaches the second threshold level, wherein the second threshold level is different than the first threshold level and the voltage level stored across the storage element reaches the second threshold level within a first equalizing pulse after the vertical reset pulse was activated.

A vertical reset generator circuit for generating a vertical reset signal representing a vertical reset time period within a video system, the circuit comprising:

• a. a receiving circuit configured for receiving a composite video signal including equalizing pulses and serration pulses, wherein each of the equalizing and serration pulses have a first level and a second level;
• b. a separating circuit coupled to the receiving circuit for separating the equalizing and serration pulses from the composite video signal;
• c. a storage element for storing a level of charge;
• d. a charging and discharging circuit coupled to the storage element for charging and discharging the level of charge stored within the storage element, wherein the level of charge is charged during the first level and discharged during the second level;
• e. a monitoring circuit coupled to the storage element for monitoring the level of charge within the storage element;
• and
• f. a hysteretic signal generating circuit coupled to the monitoring circuit for activating a vertical reset signal when the level of charge reaches a first threshold level and deactivating the vertical reset signal when the level of charge reaches a second threshold level, wherein the second threshold level is less than the first threshold level, and further wherein the level of charge reaches the first threshold level within a first serration pulse after a series of equalizing pulses.