Browse Prior Art Database

Signal Recovery System with Low Pass Filter

IP.com Disclosure Number: IPCOM000090686D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Hertrich, FR: AUTHOR [+2]

Abstract

The signal recovery system reproduces signals recorded on magnetic media 10 sensed by reproducing head 11. The sensed signal is supplied over line 12 through amplifier 13 to low-pass filter 14. The latter accentuates the low-frequency components of the sensed signal and provides some phase compensation. Filter 14 supplies the filtered signal to signal processing circuits 15 for detection of the recorded digital data. Analysis of sensed signals from phase-encoded recorded signals shows that the first three harmonics F, 2F, 3F contain most of the information that is recorded. Frequency F is 1/T where T is the duration of a bit period in phase-encoded recording. In a sensed signal having a signal-to-noise ratio of 10:1, noise in the system often exceeds the amplitude of the reproduced signal above the third harmonic.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 89% of the total text.

Page 1 of 2

Signal Recovery System with Low Pass Filter

The signal recovery system reproduces signals recorded on magnetic media 10 sensed by reproducing head 11. The sensed signal is supplied over line 12 through amplifier 13 to low-pass filter 14. The latter accentuates the low- frequency components of the sensed signal and provides some phase compensation. Filter 14 supplies the filtered signal to signal processing circuits 15 for detection of the recorded digital data. Analysis of sensed signals from phase-encoded recorded signals shows that the first three harmonics F, 2F, 3F contain most of the information that is recorded. Frequency F is 1/T where T is the duration of a bit period in phase-encoded recording. In a sensed signal having a signal-to-noise ratio of 10:1, noise in the system often exceeds the amplitude of the reproduced signal above the third harmonic. For a signal recovery system in which only small phase corrections, lag, are desired, the resonance point fr of filter 14 is chosen to be close to 0.5F with a relatively linear change in phase toward the higher harmonics as shown by line 20. The filter attenuation characteristics are indicated by line 21. In other signal recovery systems where substantial phase corrections are desired, the resonance point fr of filter 14 is chosen to lie closer to fundamental frequency F. The utilization of filter 14 also reduces peak shift effects on signal detection. This advantage is caused by accentuating the low-frequenc...