Apparatus and method for updating thresholds for peak and valley systems

An apparatus for updating thresholds in a radio frequency detection decoder system comprising:

• a first comparator, said first comparator performing a comparison between an input signal and a first predetermined threshold, said first comparator producing a first output signal based upon said comparison;
• a second comparator, said second comparator performing a comparison between said input signal and a second predetermined threshold, said second comparator producing a second output signal based upon said comparison;
• means for determining a first mean value, said means for determining a first mean value coupled to said first comparator and receiving said first output signal and determining a first mean value thereof, said means for determining a first mean value generating a first mean value output signal;
• means for determining a second mean value, said means for determining a second mean value coupled to said second comparator and receiving said second output signal and determining a second mean value thereof, said means for determining a second mean value generating a second mean value output signal;
• means for determining a first deviation, said means for determining a deviation coupled to said first comparator and said means for determining a first mean value, said means for determining a first deviation receiving said first output signal and said first mean value output signal and determining a deviation between said first output signal and said first mean value output signal, said means for determining a deviation generating a first deviation output signal;
• means for determining a second deviation, said means for determining a second deviation coupled to said second comparator and said means for determining a second mean value, said means for determining a second deviation receiving said second output signal and said second mean value output signal and determining a deviation between said second output signal and said second mean value output signal;
• a third comparator, said third comparator coupled to said means for determining a first deviation, said third comparator performing a third comparison between said first deviation output signal and a first predetermined deviation threshold, said third comparator producing a third output signal based upon said third comparison;
• a fourth comparator, said fourth comparator coupled to said means for determining a second deviation, said fourth comparator performing a fourth comparison between said second deviation output signal and a second predetermined deviation threshold, said fourth comparator producing a fourth output signal based upon said fourth comparison;
• a first memory element, said first memory element coupled to said third comparator and said means for determining a first mean value, said first memory element receiving said first mean value output signal and said first deviation output signal, said first memory element selectively storing said first mean value output signal based upon said third output signal;
• a second memory element, said second memory element coupled to said fourth comparator and said means for determining a second mean value, said second memory element receiving said second mean value output signal and said second deviation output signal, said second memory element selectively storing said second mean value output signal based upon said fourth output signal;
• and
• means for computing said first and second predetermined thresholds said means for computing coupled to said first and second memory elements, wherein, in use, said first and second predetermined thresholds are a function of said first and second mean value output signals that are selectively stored in said first memory element and said second memory element respectively.

In a detection decoder comprising a plurality of comparators, a plurality of memory elements, and means for computation, a method for updating upper and lower threshold signals in a detection decoder comprising the steps of:

• (a) acquiring a sample of an input signal;
• (b) making a comparison between said sample of said input signal and the upper threshold signal and producing a second signal based on said comparison;
• (c) making a second comparison between said sample of said input signal and the lower threshold signal and producing a third signal based on said second comparison;
• (d) determining the mean of said second signal on a first periodic basis;
• (e) determining the mean of said third signal on a second periodic basis;
• (f) determining the deviation of the second signal from the mean of the second signal on said first periodic basis;
• (g) determining the deviation of the third signal from the mean of the third signal on said second periodic basis;
• (h) comparing the deviation of the second signal from the mean of the second signal with a first predetermined deviation threshold;
• (i) comparing the deviation of the third signal from the mean of the third signal with a second predetermined deviation threshold;
• (j) updating the upper and lower threshold signals if the deviation of the second signal from the mean of the second signal is less than the first predetermined deviation threshold;
• and
• (k) updating the upper and lower threshold signal if the deviation of third signal from the mean of the third signal is less than the second predetermined deviation threshold.

An improved detection decoder comprising:

• a receiver, said receiver receiving an RF signal and producing a detector input signal;
• first means for detection, said first means detecting a peak signal magnitude of said detector input signal and producing a peak output signal corresponding thereto;
• second means for detection, said second means detecting a valley signal magnitude of said detector input signal and producing a valley output signal corresponding thereto;
• first means for computing, said first means for computing coupled to said first means for detection and receiving said peak output signal, said first means for computing calculating a mean of said peak output signal and producing a mean peak output signal, said first means for computing further calculating a deviation of the peak output signal over a predetermined time interval and producing a peak deviation output signal;
• second means for computing, said second means for computing coupled to said second means for detection and receiving said valley output signal, said second means for computing calculating a mean of said valley output signal and producing a mean output signal, said second means for computing further calculating a deviation of the valley output signal over a predetermined time interval and producing a valley deviation output signal;
• first means for comparing, said first means for comparing coupled to said first means for computing and comparing said peak deviation output signal to a first predetermined deviation threshold, said first means for comparing producing a first deviation output signal;
• and
• second means for comparing, said second means for comparing coupled to said second means for computing and comparing said valley deviation output signal to a second predetermined deviation threshold, said second means for comparing producing a second deviation output signal;
• and
• a threshold calculator, said threshold calculator receiving said mean peak output signal, said mean valley output signal, said first deviation output signal, and said second deviation output signal, said threshold calculator producing an upper and lower threshold depending upon said first deviation output signal and said second deviation output signal, respectively.