DETAILED DESCRIPTION OF THE INVENTION My co-pending application, Ser.
No.
367,618, filed June 6, 1973, now U.
S.
Pat.
No.
3,860,760, which application is hereby incorporated by reference, discloses several electronic techniques for automatically translating electrical signals from a first frequency band to a second frequency band using the principles of either time compression or expansion.
More particularly, FIG.
8 of my patent discloses an apparatus wherein samples of an analog input signal are written into a multi-stage analog memory at a first clock rate and subsequently read-out from the memory at a second clock rate.
The compression ratio of the device is the ratio of the two clock rates and for time compression the read-out rate is higher than the write-in rate.
Thus, while the analog memory is being read-out at the faster rate, the oldest samples stored in the analog memory are continuously refreshed with new samples which are inputted at the slower clock rate.
For time expansion the read-out clock runs at a slower rate than the write-in clock and, as is generally true for time expansion techniques, some of the incoming analog samples are never read-out from the memory and are lost.
The apparatus shown in FIG.
8 of my above-referenced patent requires a multi-stage analog memory and a large number of write-in and read-out sampling gates.
Accordingly, it may be too complex and too expensive for certain signal processing applications.
FIG.
1 of the instant patent application discloses, therefore, an electro-mechanical equivalent of the time compressor or expander shown in FIG.
8 of U.
S.
Pat.
No.
3,860,760 and does not suffer from the above-discussed disadvantages.
As shown in FIG.
1, the analog memory of the referenced patent is replaced by a thin, annular disc of magnetic material 10.
Disc 10 is rigidly secured to a cylindrical shaft 11 by means of a pair of clamps 12--12.
A first support disc 13 is rotatably mounted about shaft 11 by means of a collar 14.
Disc 13 supports a dependant magnetic read-head 16 which is electrically connected to a pair of slip-rings 17--17 mounted to the upper surface of disc 13
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