Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site wateng.UUCP Path: utzoo!watmath!watdaisy!wateng!ksbszabo From: ksbszabo@wateng.UUCP (Kevin S. B. Szabo) Newsgroups: net.audio Subject: Re: CD in cars and other MYTHS ! Message-ID: <83@wateng.UUCP> Date: Thu, 9-Jun-83 23:17:08 EDT Article-I.D.: wateng.83 Posted: Thu Jun 9 23:17:08 1983 Date-Received: Fri, 10-Jun-83 01:47:12 EDT References: hou5e.494, <163@micomz.UUCP> Organization: U of Waterloo, Ontario Lines: 29 I find it somewhat incomprehensible to still see people say something is impossible, especially someone who is obviously a little more technically oriented than the general public. I believe the comment that CD's are impossible due to the stylus tracking problem misses on one main point. It is precisely due to the fact that no contact with the playing surface is required that tracking is simplified. The mass of the "stylus" is no longer a factor when playing since the stylus is probably anchored with some form of leadscrew, instead of floating as is necessary with the mechanical pickup. Fine positioning of the actual pickup may still be done by magnetic means, the servo amplifiers would of course have to be accurate enough to compensate for the forces exerted on the small pickup. I do not consider the design of these amplifiers to be impossible either. Problems of wow and flutter can also be dealt with in the car environment. Since the information off the disk is already in a digital format it is not a difficult task to perform a delay line type operation on the data. This circuit can take take at a certain rate (with jitter, also known as wow and flutter) and output a stream of data at a constant rate. Remember that the digital information is sampled, and hence has a recoverable clock that allows regeneration of timing information. Standard records of course have no such information present. Note that challenging problems are met with new and interesting solutions. The problem of achieving the disk - head distances seen in present disk drives would be difficult to surmount without flying heads. I think this problem is of similar difficulty. Also note that I never said it would be a) cheap or b) easy. Zazzy