Direct IF Synthesis of Vector Modulated Signals using Real-Time Signal Processing

Generating nonlinear modulation with minimum memory requirements

“…This means that only the symbol values need to be stored in memory rather than a highly oversampled waveform. The details on implementing G(z) as a pulse shaping filter can be found in [2]. Second, G(z) can simply interpolate the input waveform by a small integer factor, K, reducing the normalized signal bandwidth by K. This reduces the complexity of the Farrow Structure significantly since the bandwidth of the signal to be reconstructed is reduced.…”

“…1, developed in [1], [2], can be made to support nonlinear modulation. All that is needed is an integrator and sin/cos computation.…”

“…An analysis of the performance of the original system of Fig. 1 may be found in [1], [2]. The modifications to this system to support nonlinear modulation add a second input source to the Farrow Structure.…”

“…The new input source is the complex envelope of a nonlinearly modulated signal. In order to control interpolation image distortion, the bandwidth of the complex envelope must be taken into consideration when designing the interpolation system (see [1], [2] for further details).…”