US5438460A — Asynchronous gain adjustment for PRML disk drive …

Claim 1

Independent Claim 120 words

A method of gain adjustment for data detection in a partial-response maximum-likelihood (PRML) data channel including a variable gain amplifier (VGA) coupled to an analog to digital converter (ADC) having a normal operating range, an analog envelope detector not being utilized with said PRML, said method comprising the steps of: detecting a plurality of samples from the ADC by asynchronous sampling during an idle mode of the PRML channel; sequentially comparing each of said detected plurality of samples with a zero threshold value; sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and determining a gain adjustment correction value utilizing said sequentially compared values.

Claim 2

Independent Claim 120 words

A method of gain adjustment for data detection in a partial-response maximum-likelihood (PRML) data channel including a variable gain amplifier (VGA) coupled to an analog to digital converter (ADC) having a normal operating range, an analog envelope detector not being utilized with said PRML, said method comprising the steps of: detecting a plurality of samples from the ADC by asynchronous sampling during an idle mode of the PRML channel; sequentially comparing each of said detected plurality of samples with a zero threshold value; sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and determining a gain adjustment correction value utilizing said sequentially compared values.

Claim 3

Dependent Claim 22 words

A method as recited in claim 1 further comprising the step of: applying said determined gain adjustment correction value to the VGA.

Claim 4

Dependent Claim 37 words

A method as recited in claim 1 wherein the step of comparing said absolute value of said detected samples with said predetermined maximum threshold value identifies a saturation operation of the ADC responsive to identifying equal values.

Claim 5

Dependent Claim 83 words

A method as recited in claim 1 wherein the step of sequentially comparing said absolute value of each of said detected plurality of samples with a said predetermined minimum threshold value includes the step of: identifying an amplitude of a plurality of sample values from the ADC; and comparing said amplitude of said detected samples with said predetermined minimum threshold value to identify a substantially null signal operation of the ADC responsive to said identified amplitude being less than said predetermined threshold value.

Claim 6

Dependent Claim 54 words

A method as recited in claim 4 further includes the steps of: determining a gain adjustment correction value corresponding to a maximum positive correction value when a predetermined number of said sequentially compared values identify a substantially null signal operation of the ADC; and applying said determined gain adjustment correction value to the VGA.

Claim 7

Dependent Claim 41 words

A method as recited in claim 3 further includes the steps of: determining a gain adjustment correction value corresponding to a maximum negative correction value when a predetermined number of said sequentially compared values identify said saturation operation of the ADC.

Claim 8

Dependent Claim 32 words

A method as recited in claim 1 further includes the step of detecting a plurality of samples from the ADC by synchronously sampling during an acquisition read mode of the PRML channel.

Claim 9

Dependent Claim 126 words

Apparatus for gain adjustment for data detection in a partial-response maximum-likelihood (PRML) data channel including an analog to digital converter (ADC) having a normal operating range, and a variable gain amplifier (VGA) coupled to the ADC, an analog envelope detector not being utilized with said PRML, said apparatus comprising: asynchronous sampling means for detecting a plurality of samples from the ADC during an idle mode of the PRML channel; means for sequentially comparing each of said detected plurality of samples with a zero threshold value; means for sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and means for determining a gain adjustment correction value utilizing said sequentially compared values.

Claim 10

Dependent Claim 126 words

Apparatus for gain adjustment for data detection in a partial-response maximum-likelihood (PRML) data channel including an analog to digital converter (ADC) having a normal operating range, and a variable gain amplifier (VGA) coupled to the ADC, an analog envelope detector not being utilized with said PRML, said apparatus comprising: asynchronous sampling means for detecting a plurality of samples from the ADC during an idle mode of the PRML channel; means for sequentially comparing each of said detected plurality of samples with a zero threshold value; means for sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and means for determining a gain adjustment correction value utilizing said sequentially compared values.

Claim 11

Dependent Claim 19 words

Apparatus as recited in claim 8 further comprising: means for providing said gain adjustment correction value to said VGA.

Claim 12

Dependent Claim 45 words

Apparatus as recited in claim 8 wherein said means for sequentially comparing said absolute value of each of said detected plurality of samples include: means for maximum threshold comparing said sampled values to detect a saturation operation of said ADC responsive to equal compared values.

Claim 13

Dependent Claim 54 words

Apparatus as recited in claim 8 wherein said means for sequentially comparing said absolute value of each of said detected plurality of samples include: means for minimum threshold comparing said sampled values to detect a substantially null signal operation of said ADC responsive to compared values of less than said predetermined minimum threshold value.

Claim 14

Dependent Claim 172 words

A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel, an analog envelope detector not being utilized with said PRML, comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; an analog to digital converter (ADC) coupled to said transducer means for converting an analog input signal to digital sample values within a normal operating range; asynchronous sampling means for detecting a plurality of samples from the ADC during an idle mode of the PRML channel; means for sequentially comparing each of said detected plurality of samples with a zero threshold value; means for sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and means for determining a gain adjustment correction value utilizing said sequentially compared values.

Claim 15

Dependent Claim 172 words

A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel, an analog envelope detector not being utilized with said PRML, comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; an analog to digital converter (ADC) coupled to said transducer means for converting an analog input signal to digital sample values within a normal operating range; asynchronous sampling means for detecting a plurality of samples from the ADC during an idle mode of the PRML channel; means for sequentially comparing each of said detected plurality of samples with a zero threshold value; means for sequentially comparing an absolute value of each of said detected plurality of samples with a predetermined maximum threshold value and a predetermined minimum threshold value; and means for determining a gain adjustment correction value utilizing said sequentially compared values.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-07-31	1999-01-30	1999-08-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-07-31	2003-01-30	2003-08-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-07-31	2007-01-30	2007-08-01	$7700.00	Window Closed / Lapsed

Asynchronous gain adjustment for PRML disk drive systems

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