TDM-FDM Conversion Requiring Reduced Computation Complexity

We present an approach to perform the conversion between two widely used multiplexing techniques in telephony, time division, multiplex (TDM) to frequency division multiplex (FDM), using digital signal processing techniques. By exploiting some results from the theory of computational complexity we reduce considerably the number of computations required. Furthermore the use of only nonrecursive (FIR) filters whose coefficients are expressed in the canonical signed digit code permits a 16 bit implementation requiring no multiplications and only additions with concurrent shifts which further simplifies the required circuitry.