Rangeless servo notch optimization

A disc drive servo control system test system for setting notch filters in the servo control system control loop of disc drive, the test system comprising:

• a memory module;
• a resonance detection module for detecting resonance peaks in a disc drive open loop response spectrum stored in the memory;
• and
• a dynamic notch filter module for dynamically setting a notch filter in the servo control system for each resonance peak that exceeds a predetermined threshold amplitude in the open loop response in order of resonance peak amplitude.

A method for placing a predetermined number of notch filters in a data storage device servo control system comprising steps of:

• a) selecting a predetermined frequency range;
• b) storing a response spectrum of noise generated by the data storage device in the predetermined frequency range in a memory;
• c) calculating an open loop response for the response spectrum;
• d) determining whether any noise frequencies in the open loop response exceed a selected gain threshold;
• e) if there are any noise frequencies that exceed the gain threshold, calculating a notch filter for each noise frequency;
• f) mathematically applying the notch filter into the servo control system;
• g) repeating steps (c)-(g) until no noise frequencies exceed the gain threshold;
• h) select another frequency range;
• i) if another frequency range is less than a maximum range, repeat steps (c) through (i);
• j) reduce the gain threshold;
• and
• k) repeat steps (c)-(j) until the predetermined number of notch filters have been placed.

A system comprising:

• a memory to store information relating to a frequency response of a channel, the channel having the frequency response across a frequency range;
• and
• a processor to generate a compensation filter for the channel by:
• (a) storing frequency response information for a portion of the frequency range into the memory;
• (b) setting an adjustable amplitude threshold for frequencies within the portion of the frequency range;
• (c) identifying frequencies at which an open loop response associated with the channel has an amplitude peak that exceeds the set amplitude threshold within the portion of the frequency range;
• and
• (d) applying a compensation filter comprising one or more notch filters to substantially attenuate the amplitude peak at each of the identified frequencies.

A method to generate a compensation filter for a channel, the method comprising:

• (a) providing a channel with a frequency response across a frequency range;
• (b) storing frequency response information for a portion of the frequency range;
• (c) setting an adjustable amplitude threshold for frequencies within the portion of the frequency range;
• (d) identifying frequencies at which an open loop response associated with the channel has an amplitude peak that exceeds the set amplitude threshold within the portion of the frequency range;
• and
• (e) applying a compensation filter comprising one or more notch filters to substantially attenuate the amplitude peak at each of the identified frequencies.