Discrete transform systems using permuter memories

Apparatus for taking the discrete transform of a sampled analog input signal, consisting of N data samples, g.sub.0, g.sub.1, . . ., comprising:

• means, connected to the input signal, for connecting the input signal to either of two connections;
• means, connected to one of the connections of the connecting means, for sampling the first data sample, g.sub.0, and holding it for 3N time units,
• means, connected to the other connection of the connecting means, for integrating the input signal, excluding the g.sub.0 sample, for N-1 time units;
• means, whose input is connected to the output of the integrating means, for amplifying the integrated signal;
• a first summing means, whose two inputs are connected to the outputs of the means for sampling and holding and of the amplifying means, for summing its two input signals, the output signal being G.sub.0, the zero frequency term of the transform;
• a first permuting means, connected to the said other connection of the connecting means, for performing a permutation on its input signal;
• means, whose input is connected to the output of the first permuting means, for filtering the permuted signals;
• and
• second means, having inputs connected to the outputs of the sampling and holding means and of the filtering means, for summing its input signals, and whose output comprises the transformed terms G.sub.1....., G.sub.N-1.