Method for automatic gain control, for instance in a telecommunication system, device and computer program product therefor
View Patent ↗A method for automatic gain control of an output signal generated from an input signal includes measuring power of the output signal. Measuring power of the output signal includes setting at least one power threshold, measuring a rate of crossing of the at least one power threshold by the output signal over an observation window, and deriving from the rate of crossing a measured power of the output signal. The method further includes providing a reference power, subtracting the measured power from the reference power to obtain an error signal, and mixing the input signal with the error signal. An analog-to-digital conversion is performed on a result of the mixing to obtain a gain-controlled output signal.
1. A method for automatic gain control of an output signal generated from an input signal, the method comprising:
measuring power of the output signal comprising
setting at least one power threshold,
measuring a rate of crossing of the at least one power threshold by the output signal over an observation window, and
deriving from the rate of crossing a measured power of the output signal,
providing a reference power,
subtracting the measured power from the reference power to obtain an error signal,
mixing the input signal with the error signal, and
performing an analog-to-digital conversion on a result of the mixing to obtain a gain-controlled output signal.
2. A method of claim 1 ,
wherein deriving the measured power comprises:
accumulating a number of the crossings of the at least one power threshold by the output signal; and
calculating the rate of the crossings as a statistical expectation from the number of crossings.
3. A method of claim 2 , wherein deriving the measured power further comprises applying at least one threshold function to the statistical expectation to obtain the measured power.
4. A method of claim 3 , wherein the at least one threshold function comprises an inverse error function.
5. A method of claim 3 , further comprising setting multiple thresholds and applying a multi-threshold function to the statistical expectation to obtain the measured power.
6. A method of claim 3 , wherein the at least one threshold function is evaluated by retrieving values in a look up table.
7. A method of claim 1 , further comprising filtering the error signal through a loop filter prior to being mixed with the input signal.
8. A method of claim 1 , wherein mixing the error signal with the input signal is performed by amplifying the input signal with a variable gain function of the error signal.
9. A method according to claim 1 , further comprising converting the measured power of the output signal from a linear value to a logarithmic value.
10. A method according to claim 1 , wherein the input signal is received by a telecommunications system.
11. An automatic gain control device for providing a gain-controlled output signal from an input signal, the automatic gain control device comprising:
a power measurement module for measuring power of the output signal and comprising
at least one threshold module for measuring a rate of crossing of at least one power threshold by the output signal over an observation window, said at least one threshold module comprising an accumulator for accumulating a number of crossings of at least one power threshold by the output signal, and for measuring the rate of the crossings as a statistical expectation from the number of crossings, and
at least one power module for deriving from the rate of crossing a measured power.
12. An automatic gain control device of claim 11 , further comprising:
a summing node for subtracting the measured power from a reference power to obtain an error signal;
a mixer node for mixing the input signal with the error signal; and
an analog-to-digital converter for converting a result of the mixing to obtain the gain-controlled output signal.
13. An automatic gain control device of claim 12 , further comprising a loop filter for filtering the error signal prior to mixing the filtered error signal with the input signal.
14. An automatic gain control device of claim 12 , wherein said mixer node mixes the error signal with the input signal by amplifying the input signal with
15. An automatic gain control device of claim 11 , wherein said at least one threshold module comprises at least one threshold comparator for applying a threshold function to the statistical expectation to obtain the measured power.
16. An automatic gain control device of claim 15 , wherein said at least one threshold comparator implements the threshold function as an inverse error function.
17. An automatic gain control device of claim 15 , wherein said at least one threshold module comprises a plurality of threshold comparators for applying a multi-threshold function to the statistical expectation to obtain the measured power.
18. An automatic gain control device of claim 17 , wherein said at least one power module includes a look up table containing values for the multi-threshold function. a variable gain function of the error signal.
19. An automatic gain control device of claim 11 , further comprising a linear-to-logarithmic converter for converting the measured power from a linear value to a logarithmic value.
20. A receiver for a telecommunications system comprising:
an input for receiving an input signal; and
an automatic gain control device downstream from said input for providing a gain-controlled output signal from the input signal, said automatic gain control device comprising
a threshold module for measuring a rate of crossing of at least one power threshold by the output signal over an observation window,
a power module for deriving from the rate of crossing a measured power of the output signal,
a summing node for subtracting the measured power from a reference power to obtain an error signal,
a mixer node for mixing the input signal with the error signal, and
an analog-to-digital converter for converting a result of the mixing to obtain a gain-controlled output signal.
21. A receiver of claim 20 , wherein said threshold module comprises an accumulator for accumulating a number of crossings of at least one power threshold by the output signal, and for measuring the rate of the crossings as a statistical expectation from the number of crossings.
22. A receiver of claim 21 , wherein said threshold module comprises at least one threshold comparator for applying a threshold function to the statistical expectation to obtain the measured power.
23. A receiver of claim 22 , wherein said at least one threshold comparator implements the threshold function as an inverse error function.
24. A receiver of claim 22 , wherein said threshold module comprises a plurality of threshold comparators for applying a multithreshold function to the statistical expectation to obtain the measured power.
25. A receiver of claim 22 , wherein said power module includes a look up table containing values for the multi-threshold function.
26. A receiver of claim 20 , further comprising a loop filter for filtering the error signal prior to mixing the filtered error signal with the input signal.
27. A receiver of claim 20 , wherein said mixer node mixes the error signal with the input signal by amplifying the input signal with a variable gain function of the error signal.
28. A receiver of claim 20 , wherein the input signal is based upon at least one of the following GSM, UMTS, CDMA2000, 1395 and WBCDMA standards.
29. A computer-readable medium for automatic gain control of an output signal generated from an input signal, the computer-readable medium having computer-executable instructions for causing a user computer to perform steps comprising:
setting at least one power threshold;
measuring a rate of crossing of the at least one power threshold by an output signal over an observation window; and
deriving from the rate of crossing a measured power of the output signal;
subtracting the measured power from a reference power to obtain an error signal;
mixing the input signal with the error signal; and
performing an analog-to-digital conversion on a result of the mixing to obtain a gain-controlled output signal.
30. A computer-readable medium of claim 29 , wherein containing data for deriving the measured power further comprises data for accumulating a number of the crossings of the at least one power threshold by the output signal; and calculating the rate of the crossings as a statistical expectation from the number of crossings.
31. A computer-readable medium of claim 30 , wherein containing data for deriving the measured power further comprises data for applying at least one threshold function to the statistical expectation to obtain the measured power.
32. A computer-readable medium of claim 31 , wherein containing data for deriving the measured power further comprises data for setting multiple thresholds and applying a multithreshold function to the statistical expectation to obtain the measured power.
33. A computer-readable medium of claim 31 , wherein the at least one threshold function is evaluated by retrieving values in a look up table.
34. A computer-readable medium of claim 29 further having computer-executable instructions for causing the user computer to perform the following steps:
filtering the error signal through a loop filter prior to being mixed with the input signal.
35. A computer-readable medium of claim 29 , wherein containing data for mixing the input signal with the error signal further comprises data so that mixing the error signal with the input signal is performed by amplifying the input signal with a variable gain function of the error signal.
36. A method for automatic gain control of an output signal generated from an input signal, the method comprising:
measuring power of the output signal comprising
setting at least one power threshold,
measuring a rate of crossing of the at least one power threshold by the output signal over an observation window, and
deriving from the rate of crossing a measured power of the output signal, the deriving comprising
accumulating a number of the crossings of the at least one power threshold by the output signal,
calculating the rate of the crossings as a statistical expectation from the number of crossings, and
applying at least one threshold function to the statistical expectation to obtain the measured power.
37. A method of claim 36 , further comprising:
providing a reference power;
subtracting the measured power from the reference power to obtain an error signal;
mixing the input signal with the error signal; and
performing an analog-to-digital conversion on a result of the mixing to obtain a gain-controlled output signal.
38. A method of claim 36 , wherein the at least one threshold function comprises an inverse error function.
39. A method of claim 36 , further comprising setting multiple thresholds and applying a multithreshold function to the statistical expectation to obtain the measured power.
40. A method of claim 36 , wherein the at least one threshold function is evaluated by retrieving values in a look up table.
41. A method according to claim 36 , further comprising converting the measured power of the output signal from a linear value to a logarithmic value.
42. A method according to claim 36 , wherein the input signal is received by a telecommunications system.
43. An automatic gain control device for providing a gain-controlled output signal from an input signal, the automatic gain control device comprising:
a power measurement module for measuring power of the output signal and comprising
at least one threshold module for measuring a rate of crossing of at least one power threshold by the output signal over an observation window, and comprising
an accumulator for accumulating a number of crossings of said at least one power threshold by the output signal, and for measuring the rate of the crossings as a statistical expectation from the number of crossings, and
at least one threshold comparator for applying a threshold function to the statistical expectation to obtain the measured power.
44. An automatic gain control device of claim 43 , further comprising:
a summing node for subtracting the measured power from a reference power to obtain an error signal;
a mixer node for mixing the input signal with the error signal; and
an analog-to-digital converter for converting a result of the mixing to obtain the gain-controlled output signal.
45. An automatic gain control device of claim 43 , wherein said at least one threshold comparator implements the threshold function as an inverse error function.
46. An automatic gain control device of claim 43 , wherein said at least one threshold module comprises a plurality of threshold comparators for applying a multi-threshold function to the statistical expectation to obtain the measured power.
47. An automatic gain control device of claim 46 , wherein said at least one power module includes a look up table containing values for the multi-threshold function.
48. An automatic gain control device of claim 43 , further comprising a linear-to-logarithmic converter for converting the measured power from a linear value to a logarithmic value.