Method and apparatus for generating a reference television signal
View Patent ↗CW lock is conducted with less manual operation. A first input 22 receives a black burst (BB) signal from a key TV station. A second input 30 receives a continuous wave (CW) signal having an accurate, known frequency. A phase adjust signal generator 24 generates a reset signal having a known phase relationship with regard to the key TV station BB signal. The reset signal is used as a phase adjust signal. A PLL 32 receives the CW signal to provide clock. A counter 34 receives the clock and provides a frame pulse signal for synchronizing the key and local TV signals at a local TV station wherein the BB signal of the local station may be derived from the frame pulse signal. The counter 34 uses the reset signal to adjust the phase relationship between the key TV station BB signal and the frame pulse to a desired phase relationship based upon the key TV station BB signal.
1. A reference television signal generator comprising:
a first input receiving a first reference television signal;
a second input receiving a reference frequency signal having a known accurate frequency;
a phase adjust signal generator that generates as a phase adjust signal a frame pulse having a known phase relationship with the first reference television signal; and
a signal generator generating a second reference television signal wherein the signal generator adjusts the phase relationship between the first reference television signal and the second reference television signal to a desired phase relationship using the frame pulse when the first reference television signal exists at the first input and the signal generator locks the phase of the second reference television signal to that of the reference frequency signal when the first reference television signal does not exist at the first input.
2. The reference television signal generator as recited in claim 1 wherein the first reference television signal is controlled to be provided to the first input at a predetermined time.
3. The reference television signal generator as recited in claim 1 wherein the phase adjust signal generator derives a synch signal from the first reference television signal and generates the frame pulse from the derived synch signal.
4. The reference television signal generator as recited in claim 1 wherein the signal generator has a counter that generates a pulse when the counted number reaches a predetermined number or the counter receives the frame pulse.
5. The reference television signal generator as recited in claim 4 wherein the pulse that the counter generates is a frame pulse for generating the second reference television signal.
6. The reference television signal generator as recited in claim 1 wherein the first reference television signal is a black burst signal from a key TV station.
7. The reference television signal generator as recited in claim 1 wherein the reference frequency signal is a continuous wave signal.
8. The reference television signal generator as recited in claim 1 wherein the second reference television signal is used at a local TV station.