| 摘要 |
In accordance with a presently preferred embodiment of the invention, a source of radiation produces a pair of tracking spots focussed on a record carrier and nominally disposed toward opposite sides of a record track on the record carrier. After interaction with the record carrier, each of the tracking spots is detected to produce respective tracking signals. The components of each tracking signal which correspond to the information signal recorded on the record track are compared and a tracking error signal is produced based upon such comparison. By so producing the tracking error signal, proper tracking can be maintained irrespective of the polarity of the record carrier.
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