Abstract: The robust coding system makes use of a robust bar code on a label to enable a label reading system to automatically reconstruct label indicia information, even though the label has been damaged and is partially obliterated. An error correcting code is incorporated into the bar code sequence imprinted on the label to detect and correct a plurality of errors in the bar code. The error correcting bar code digits can be interleaved with the data imprinted in bar code form on the label or appended thereto. In addition, when the robust coding system is used on labels for data media cartridges, additional information is included in the bar code field to identify the type of media contained in the media cartridge.

Abstract: An automatic calibration system for signal amplifier circuits uses a single complex power signal to replace the formerly used four separate sinewave frequencies and a square wave signal. In the illustrated embodiment of the invention, the power signal is recorded on a magnetic tape and is played back through reproduce equalizer circuits which apply the reproduced signal to a tracking frequency converter to produce an amplitude measurement of each of the preselected frequency components forming the complex power signal. The amplitude measurements are referenced to the power signal's actual harmonic content to enable an adjustment of the equalizer circuits to produce a minimum error in the playback signal. A bandpass phase response measurement is also performed on the reproduced signal by comparing the phase difference between the reproduced signal and a synthesized power signal after the amplitude compensation produced by the amplitude measurements.