Systems and methods for medium proximity detection in a read channel
View Patent ↗A contact event between a sensing device and a storage medium is detected by receiving a signal indicating a physical proximity between the sensing device and the storage medium; generating a plurality of frequency bin outputs; comparing one or more frequency bin outputs to a corresponding first level threshold to yield a corresponding comparator output; summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value; comparing the aggregated value to an aggregate threshold to yield an aggregate output; and generating a contact event output if one or more of a first group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value and a predefined minimum number of a second group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value.
1. A method for detecting a contact event between a sensing device and a storage medium, comprising:
receiving a signal operable to indicate a physical proximity between the sensing device and the storage medium;
processing a data set derived from the signal to generate a plurality of frequency bin outputs;
comparing one or more frequency bin outputs to a corresponding level threshold to yield a corresponding comparator output;
summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value;
comparing the aggregated value to an aggregate threshold to yield an aggregate output; and
generating a contact event output if one or more of a first group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value and a predefined minimum number of a second group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value.
2. The method of claim 1 , wherein the comparator output is asserted to indicate the corresponding frequency bin output is greater than the corresponding level threshold, and wherein the aggregate output is asserted to indicate that the aggregated value is greater than the aggregate threshold.
3. The method of claim 1 , wherein the signal provides a contact signature when the sensing device is within a predefined physical proximity to the storage medium.
4. The method of claim 1 , wherein the method further comprises:
converting a derivative of the signal to a series of digital samples, and wherein the data set is derived from the series of digital samples.
5. The method of claim 4 , wherein the method further comprises the step of digitally filtering the series of digital samples to yield the data set.
6. The method of claim 5 , wherein the step of digitally filtering the series of digital samples further comprises the step of applying the digital samples to a cascaded-integrator comb filter and at least one infinite impulse response filter.
7. The method of claim 1 , wherein the step of processing the data set further comprises the step of applying a coordination rotation digital Computer discrete Fourier Transform algorithm to the data set.
8. The method of claim 1 , wherein a center frequency of each frequency bin output corresponds to a contact signature.
9. The method of claim 1 , wherein the sensing device is operable to provide the signal.
10. The method of claim 1 , wherein the number of prior instances of the comparator output that are included in the aggregated value corresponds to a programmable window width value.
11. The method of claim 1 , wherein the first group of the plurality of frequency bin outputs comprises frequency bin outputs that must be asserted.
12. The method of claim 1 , wherein the step of generating a contact event output further comprises generating a contact event output only if the first group of the plurality of frequency bin outputs has been asserted and the predefined minimum number of a second group of the plurality of frequency bin outputs has been asserted.
13. A non-transitory machine-readable recordable storage medium for detecting a contact event between a sensing device and a storage medium, wherein one or more software programs when executed by one or more processing devices implement the following steps:
receiving a signal operable to indicate a physical proximity between the sensing device and the storage medium;
processing a data set derived from the signal to generate a plurality of frequency bin outputs;
comparing one or more frequency bin outputs to a corresponding level threshold to yield a corresponding comparator output;
summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value;
comparing the aggregated value to an aggregate threshold to yield an aggregate output; and
generating a contact event output if one or more of a first group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value and a predefined minimum number of a second group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value.
14. A system for detecting a contact event between a sensing device and a storage medium, comprising:
an input that receives a signal operable to indicate a physical proximity between the sensing device and the storage medium;
a Discrete Fourier transform circuit that processes a data set derived from the signal to generate a plurality of frequency bin outputs;
one or more comparators for comparing one or more frequency bin outputs to a corresponding level threshold to yield a corresponding comparator output;
an adder for summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value;
one or more comparators for comparing the aggregated value to an aggregate threshold to yield an aggregate output; and
a multi-level threshold processing circuit for generating a contact event output if one or more of a first group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value and a predefined minimum number of a second group of the plurality of frequency bin outputs has an associated aggregate output set to a predefined binary value.
15. The system of claim 14 , wherein the comparator output is asserted to indicate the corresponding frequency bin output is greater than the corresponding level threshold, and wherein the aggregate output is asserted to indicate that the aggregated value is greater than the aggregate threshold.
16. The system of claim 14 , wherein the system further comprises an analog to digital converter for converting a derivative of the signal to a series of digital samples, and wherein the data set is derived from the series of digital samples.
17. The system of claim 16 , wherein the system further comprises a digital filter to filter the series of digital samples to yield the data set.
18. The system of claim 17 , wherein the digital filter comprises a cascaded-integrator comb filter and at least one infinite impulse response filter.
19. The system of claim 14 , wherein the Discrete Fourier transform circuit comprises a CORDIC discrete Fourier Transform circuit.
20. The system of claim 14 , wherein a center frequency of each frequency bin output corresponds to a contact signature.
21. The system of claim 14 , wherein the sensing device is operable to provide the signal.
22. The system of claim 14 , wherein the number of prior instances of the comparator output that are included in the aggregated value corresponds to a programmable window width value.
23. The system of claim 14 , wherein the first group of the plurality of frequency bin outputs comprises frequency bin outputs that must be asserted.
24. The system of claim 14 , wherein the multi-level threshold processing circuit generates a contact event output only if the first group of the plurality of frequency bin outputs has been asserted and the predefined minimum number of a second group of the plurality of frequency bin outputs has been asserted.
25. A system for detecting a contact event between a sensing device and a storage medium, comprising:
a memory; and
at least one hardware device, coupled to the memory, operative to:
receive a signal operable to indicate a physical proximity between the sensing device and the storage medium;
process a data set derived from the signal to generate a plurality of frequency bin outputs;
compare one or more frequency bin outputs to a corresponding level threshold to yield a corresponding comparator output;
sum the comparator output with at least one prior instance of the comparator output to yield an aggregated value;
compare the aggregated value to an aggregate threshold to yield an aggregate output; and
generate a contact event output if one or more of a first group of the plurality of frequency bin outputs has been asserted and a predefined minimum number of a second group of the plurality of frequency bin outputs has been asserted.