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Filter for PAM Operation

IP.com Disclosure Number: IPCOM000092677D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Croisier, A: AUTHOR

Abstract

The device is used for pulse-amplitude modulation data filtering. As shown on drawing 1, each signal is sampled during a period To. The samples of several signals are transmitted sequentially through a transmission line PAM channel.

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Filter for PAM Operation

The device is used for pulse-amplitude modulation data filtering. As shown on drawing 1, each signal is sampled during a period To. The samples of several signals are transmitted sequentially through a transmission line PAM channel.

In drawing 2, use is made of an acoustical delay line L working in torsional magnetostriction mode for performing sampled data filtering. PAM pulses are applied to transducer T. The latter converts pulses into a corresponding pattern of acoustical waves through L. Acoustical damper D avoids reflection of acoustical waveforms back from the end of L. Along L are placed magnets M1... Mn inducing corresponding magnetic fields H1... Hn in such line.

When an acoustical waveform is traveling in front of a magnet, an electrical signal is induced and a signal appears at the L output. This signal is proportional to amplitude A(t) of the input signal and to magnetic field value H induced by a magnet M.

If Ai(t) is the signal value corresponding to those waveforms in front of magnet Mi inducing field Hi at a given time t, the total output signal summed in R is V(t) = Epsilon(i) Ai(t). The magnets are so spaced that the Ai(t)'s are samples of the same signal. The interval between two magnets is equal to F = VTo corresponding to a delay time equal to To.

The system operates as a sampled data filtering system. The number n of samples stored and the sampling rate determine the pass band of the filter. The magnetic field value...