Collection of readback signal modulation data

Abstract

A data storage system having a read channel configured to function in a normal operation mode and a test mode. In the normal operation mode, the read channel is configured to decode a readback signal to obtain data bits. In the test mode, the read channel is configured to extract gain control loop data and/or timing control loop data from the readback signal.

1 . A method comprising:
 establishing a test mode and a normal operation mode in a read channel of a data storage device; and   collecting at least one of gain control loop data or timing control loop data from a readback signal during operation of the read channel in the test mode.   
     
     
         2 . The method of  claim 1  wherein collecting at least one of gain control loop data or timing control loop data from the readback signal during operation of the read channel in the test mode comprises extracting at least one of gain control loop data or timing control loop data from the readback signal while reading user data stored on a data storage medium in the data storage system in the test mode. 
     
     
         3 . The method of  claim 2  wherein collecting at least one of gain control loop data or timing control loop data from the readback signal during operation of the read channel in the test mode further comprises transferring the extracted at least one of gain control loop data or timing control loop data over a data transfer bus. 
     
     
         4 . The method of  claim 3  wherein collecting at least one of gain control loop data or timing control loop data from the readback signal during operation of the read channel in the test mode further comprises receiving the extracted at least one of gain control loop data or timing control loop data from the data transfer bus and storing, on a data storage medium, the extracted at least one of gain control loop data or timing control loop data. 
     
     
         5 . The method of  claim 4  and further comprising providing a common memory that stores the at least one of gain control loop data or timing control loop data, received from the data transfer bus, in the test mode, and stores data bits, received from the data transfer bus, in the normal operation mode. 
     
     
         6 . The method of  claim 5  wherein the readback signal is generated by a head that communicates with the data storage medium. 
     
     
         7 . The method of  claim 6  and further comprising reading the at least one of gain control loop data or timing control loop data from the common memory and computing a proximity between the head and the data storage medium as a function of the at least one of gain control loop data or timing control loop data read from the common memory, wherein the reading and computing are carried out by a processor that executes stored instructions. 
     
     
         8 . The method of  claim 1  wherein the timing control loop data comprises at least one of frequency control loop data or phase control loop data. 
     
     
         9 . A data storage system comprising:
 a read channel comprising:
 a normal operation mode in which the read channel is configured to decode a readback signal to obtain data bits; and 
 a test mode in which the read channel is configured to extract at least one of gain control loop data or timing control loop data from the readback signal. 
   
     
     
         10 . The data storage system of  claim 9  and further comprising a memory configured receive, via a data transfer bus, the at least one of the gain control loop data or timing control loop data in the test mode, and configured to store the at least one of the gain control loop data or timing control loop data in the test mode. 
     
     
         11 . The data storage system of  claim 10  wherein the memory is configured to receive, via the data transfer bus, data bits in the normal operation mode, and configured to store the data bits in the normal operation mode. 
     
     
         12 . The data storage system of  claim 11  wherein the memory is a non-volatile buffer memory. 
     
     
         13 . The data storage system of  claim 9  wherein the timing control loop data comprises at least one of frequency control loop data or phase control loop data. 
     
     
         14 . The data storage system of  claim 9  and further comprising a head that communicates with a data storage medium, and wherein the readback signal is generated by the head. 
     
     
         15 . The data storage system of  claim 14  and further comprising a proximity computation component that computes a proximity between the head and the data storage medium as a function of the at least one of gain control loop data or timing control loop data. 
     
     
         16 . A method comprising:
 extracting at least one of gain control loop data or timing control loop data from a readback signal obtained while reading user data stored on a data storage medium;   transferring, via a data transfer bus, the extracted at least one of gain control loop data or timing control loop data from a readback signal obtained while reading user data stored on a data storage medium; and   storing the transferred at least one of gain control loop data or timing control loop data obtained via the data transfer bus.   
     
     
         17 . The method of  claim 16  wherein the data storage medium is a part of a data storage system having a read channel that operates in either a test mode or a normal operation mode, and wherein the extracting at least one of gain control loop data or timing control loop data from the readback signal obtained while reading user data stored on the data storage medium is carried out while the read channel is operating in the test mode. 
     
     
         18 . The method of  claim 17  and further comprising providing a common memory that stores the at least one of gain control loop data or timing control loop data, received from the data transfer bus, in the test mode, and stores data bits, received from the data transfer bus, in the normal operation mode. 
     
     
         19 . The method of  claim 16  wherein the readback signal is generated by a head that communicates with the data storage medium. 
     
     
         20 . The method of  claim 19  and further comprising reading the at least one of gain control loop data or timing control loop data from the common memory and computing a proximity between the head and the data storage medium as a function of the at least one of gain control loop data or timing control loop data read from the common memory, wherein the reading and computing are carried out by a processor that executes stored instructions.