Distributing frequency references
View Patent ↗A correction processor connected to an oscillator uses precision timing signals propagated over a digital network to generate an error signal. IEEE-1588 time synchronization protocols produce precision time signals which are converted to precision interval signals. The correction processor uses the precision interval signals to count pulses of the oscillator. A correction circuit compares the counter output with a predetermined value and generates an error signal may be used to correct the oscillator or may be propagated to consumers of the oscillator. An arbitrary reference oscillator may be used to generate the precision timing signals propagated on the network, to slave other oscillators to it. The precision of the reference oscillator may be deliberately overstated to insure it is used as a master.
1. A network oscillator comprising:
a network interface for receiving precision time messages from a digital network and for using the time messages to produce precision time signals,
an oscillator producing a periodic output signal,
a processor converting the precision time signals to interval signals,
a counter gated by the interval signals and driven by the periodic output signal of the oscillator, and
the processor comparing the output of the counter to a predetermined value producing an error signal.
2. The network aware oscillator of claim 1 where the oscillator has a frequency control input and the error signal drives the frequency control input to correct the oscillator frequency.
3. The network aware oscillator of claim 2 where the error signal is an analog signal.
4. The network aware oscillator of claim 2 where the oscillator is a voltage controlled crystal oscillator.
5. The network aware oscillator of claim 2 where the oscillator is temperature stabilized.
6. The network aware oscillator of claim 2 where the oscillator is a YIG tuned oscillator.
7. The network aware oscillator of claim 2 where the oscillator is a dielectric resonant oscillator (DRO).
8. A network aware oscillator comprising:
a network interface for receiving precision time messages from a digital network and producing precision time signals using the precision time messages,
an oscillator producing a periodic output signal,
a processor converting the precision time signals to interval signals,
a counter gated by the interval signals and driven by the periodic output signal of the oscillator, and
the processor comparing the output of the counter to a predetermined value producing an error signal;
where the error signal is propagated to consumers of the oscillator output.
9. The network aware oscillator of claim 8 where the error signal is a digital signal.
10. The network aware oscillator of claim 2 where the error signal corrects for oscillator frequency error and oscillator aging.
11. A method of operating a network aware oscillator comprising:
receiving precision timing messages from a digital network,
using the precision timing messages to produce precision timing signals,
converting the precision timing signals to internal signals,
counting the output of an oscillator gated by the interval signals, and
generating an error signal from the comparison of the counter output with a predetermined value.
12. The method of claim 11 further comprising: driving a frequency control input of the oscillator using the error signal.
13. The method of claim 11 further comprising: temperature stabilizing the oscillator.
14. The method of claim 11 further comprising: propagating the error signal to consumers of the oscillator output.
15. The method of claim 11 further comprising:
generating a reference signal in an external reference oscillator,
generating precision timing signals from the reference oscillator, and
propagating the precision timing signals on the digital network.
16. The method of claim 15 wherein the reference oscillator is characterized by a true accuracy; the method further comprising publishing a network message on the digital network, indicating that the accuracy of the reference oscillator is higher than the true accuracy.