Method and a system for generating an adaptive slicer threshold

1. A method of generating an adaptive slicer threshold from a received demodulated signal, the method comprising:

detecting a maximum value of the signal over a predetermined period;

storing said detected maximum value only upon occurrence of a bit level change detected by a slope detector computing a difference between said maximum value with a previously stored minimum value and comparing said difference with respect to a first value;

detecting a minimum value of the signal over a predetermined period;

storing said detected minimum value only upon occurrence of a bit level change detected by said slope detector computing a difference between said minimum value with a previously stored maximum value and comparing said difference with respect to a second value;

averaging a number of stored maximum values and averaging a number of stored minimum values; and

calculating the slicer threshold from the average minimum and maximum values.

2. The method according to claim 1 , wherein the averages of the maximum and minimum values are calculated using a running average over the n last successive selected maximum or minimum values, n being a predetermined integer greater than 1.

3. The method according to claim 1 , wherein n ranges from 2 to 6.

4. The method according to claim 3 , wherein n is equal to 4.

5. The method according to claim 1 , wherein the step of detecting a maximum value comprises the operations of:

detecting a maximum peak of the signal during the predetermined period, the maximum signal peak corresponding to a point where the signal first-order derivative is zero and the signal second-order derivative has a negative value, and

holding the value of the detected maximum peak as the maximum value over the predetermined period.

6. The method according to claim 1 , wherein the step of determining the minimum value comprises the operations of:

detecting a minimum peak of the signal during the predetermined period, the minimum signal peak corresponding to a point where the signal first-order derivative is zero and where the signal second-order derivative has a positive value, and

holding the value of the detected minimum peak as the minimum value over the predetermined period.

7. The method according to claim 5 , wherein a new detected maximum value is used to calculate the average maximum value only if a minimum peak has been detected during the previous predetermined period, and a new detected minimum value is used to calculate the average minimum value only if a maximum peak has been detected during the previous predetermined period.

8. A system for generating an adaptive slicer threshold from a received demodulated signal, the system comprising:

a first detector to detect a maximum value of the signal over a predetermined period;

a bit level detector for detecting bit level change by computing a difference between said maximum value and a previously stored minimum value and comparing said difference with respect to a first value;

a register for storing said detected maximum value only upon occurrence of a bit level change;

a second detector for detecting a minimum value of the signal over a predetermined period; and

a register for storing said detected minimum value only upon occurrence of a bit level change by computing a difference between said minimum value and a previously stored maximum value and comparing said difference with respect to a second value,

wherein the system comprises an averaging unit operable to average a number of stored maximum values, to average a number of stored minimum values, and to calculate the slicer threshold from the average minimum and maximum values.

9. The system according to claim 8 , wherein it further comprises at least one FIFO memory to store said several maximum values and said several minimum values to be averaged.

10. The system according to claim 8 , wherein the first and/or second detectors are a maximum peak detector and a minimum peak detector, respectively.

11. The system according to claim 8 , wherein the system comprises a bit level detector associated with said at least one memory in order to activate the storage of a new minimum or maximum value only if a bit level change has been detected.