Frequency response compensation with DSP

In modern telecommunication systems, there are situations when test instruments must work over hundreds of narrowband-frequency channels. It is difficult and expensive, however, to build hardware test equipment with a flat frequency response over their full operational frequency range. In this situation simple finite impulse response (FIR) filters can be applied for gain compensation to improve an instrument's frequency response flatness. This column describes a very fast method for run time design of these filters, while minimizing storage requirements, based on test instrument calibration data.