Method for digital sampling and corresponding implementation device
A method for cadence detection in a sequence of video fields is based on at least a search for cadence patterns in a sequence of bits representative of the motion in at least a part of the field from one field to another in the field sequence. The signaling of field skip and/or field repeat commands as applied to the fields in the field sequence is considered during the cadence detection operation so as to field skips and repeats.
1. A method for measuring at least two analog signals, corresponding respectively to a first and a second phase of a three-phase motor, comprising:
creating, at successive sampling instants and at least by means of a first analog/digital converter, digital samples representing a value taken respectively by these two analog signals at these sampling instants,
selectively supplying, at each sampling instant, either of the two analog signals to the first analog/digital converter to generate a corresponding original digital sample,
combining at least two original digital samples, created for a first at least of the two analog signals at respective sampling instants, in order to form, by interpolation, a derived digital sample representing the value taken by this first analog signal at a reference instant that is offset in time in relation to each of the sampling instants of this first analog signal, and
deducing from the derived digital sample value a value of a third phase of the three-phase motor, considering the motor as stable, at the reference instant.
2. The method according to claim 1 , wherein deducing the value of the third phase of the three-phase motor comprises using both the derived digital sample value for the first analog signal and the original digital sample of a second analog signal in the deducing calculation.
3. The method according to claim 1 , in wherein the reference instant is a sampling instant of a second of the analog signals.
4. The method according to claim 1 , further including combining at least two original digital samples, created for a second of the analog signals at respective sampling instants, in order to form, by interpolation, a derived digital sample representing the value taken by this second analog signal at the reference instant.
5. The method according to claim 1 , in wherein the interpolation is linear.
6. The method according to claim 1 , in wherein at least one of the sampling instants used for the interpolation is prior to the reference instant.
7. The method according to claim 1 , further comprising storing in memory a sequence that comprises selectively supplying, at each sampling instant, either of the two analog signals to the first converter for the creation of a corresponding original digital sample, and where the sequence is also capable of being modified dynamically.
8. The method according to claim 7 , in wherein the memory resources include a set of registers of the first converter.
9. The method according to claim 7 , in wherein the memory resources include random access memory of a processor that is connected to the first converter by a DMA controller.
10. The method according to claim 1 , further comprising monitoring of phase currents of a balanced thee-phase device at a reference instant.
11. A device, including:
means for measuring at least two analog signals, configured to execute at least one operation that comprises creating, at successive sampling instants and at least by means of a first analog/digital converter, digital samples representing values taken respectively by these two analog signals at these sampling instants,
means for selectively supplying, at each sampling instant, either of the two analog signals to the first converter to generate a corresponding original digital sample,
means for combining at least two original digital samples, created for a first at least of the two analog signals at respective sampling instants, in order to form, by interpolation, a derived digital sample representing the value taken by this first analog signal at a reference instant that is temporally offset in relation to each of the sampling instants of this first analog signal, and
means for deducing from the derived digital sample a value of a third phase of a three-phase motor, considering the motor as stable, at the reference instant.
12. A method for measuring at least two analog signals using only a single analog/converter, comprising:
sampling a first one of the analog signals at a first instant in time to generate by the single analog/digital converter a first digital value;
sampling a second one of the analog signals at a second instant in time to generate by the single analog/digital converter a second digital value;
sampling the first one of the analog signals at a third instant in time to generate by the single analog/digital converter a third digital value; and
interpolating the first and third digital values relating to sampling of the first one of the analog signals at the first and third instants in time to derive a fourth digital value representing a sampling of the first one of the analog signals at about the second instant in time.
13. The method of claim 12 wherein the first, second and third instants in time are sampling instants which are periodic and defined by a sampling frequency.
14. The method of claim 12 wherein interpolating comprises linearly interpolating.
15. The method of claim 12 wherein interpolating comprises extrapolating.
16. The method of claim 12 wherein the first and second ones of the analog signals correspond to a first and a second phase of a three-phase motor, further comprising deducing a value of a third phase of the three-phase motor at about the second instant in time from the second and fourth digital values.
17. A method for measuring at least two analog signals using only a single analog/converter, comprising:
sampling a first one of the analog signals at a first and a second instants in time to generate by the single analog/digital converter a first and second digital value, respectively;
sampling a second one of the analog signals at a third and a fourth instants in time to generate by the single analog/digital converter a third and a fourth digital value, respectively;
first interpolating the first and second digital values relating to sampling of the first one of the analog signals at the first and second instants in time to derive a fifth digital value representing a sampling of the first one of the analog signals at a reference instant in time; and
second interpolating the third and fourth digital values relating to sampling of the second one of the analog signals at the third and fourth instants in time to derive a sixth digital value representing a sampling of the second one of the analog signals at about the same reference instant in time.
18. The method of claim 17 wherein the first through fourth instants in time are sampling instants which are periodic and defined by a sampling frequency.
19. The method of claim 17 wherein interpolating comprises linearly interpolating.
20. The method of claim 17 wherein interpolating comprises extrapolating.
21. The method of claim 17 wherein the first and second ones of the analog signals correspond to a first and a second phase of a three-phase motor, further comprising deducing a value of a third phase of the three-phase motor at about the reference instant in time from the fifth and sixth digital values.
22. The method of claim 17 wherein reference instant in time does not correspond with any of the first through fourth instants in time.