In the MXG, a real-time signal-processing ASIC customizes phase noise levels for both CW and modulated signals. In an important innovation, phase noise can be adjusted to different levels at different offsets, including the steep slopes of close-in noise, the flat slopes of synthesizer pedestal noise and the shallow slopes of wide offset noise.
This precise substitution capability helps designers avoid the dual hazards of over- or under-performance of their oscillators and synthesizers. Excess performance can lead to expensive designs and longer design cycles, rendering a product uncompetitive. Insufficient performance results in redesigns and product delays and the type of unpleasant surprises that engineers dread most.
OFDM signals provide a good example. Because these signals have extremely close subcarrier spacing, they are sensitive to phase noise, which reduces the orthogonality (independence) of the subcarriers and increases modulation error. Consequently, OFDM transmitters and receivers need good phase noise performance. During product development, the MXG’s injection capability allows selective addition of phase noise in terms of carrier offset, making it an excellent substitute for synthesizers and OFDM transmitters and enabling confident evaluation of receiver tolerance versus real-world transmitter performance. The result is fast, reliable optimization of design cost and performance.
Real-time baseband generation
The X-Series signal generators have a powerful internal real-time baseband generator and processor-accelerator ASIC. This supports a large number of real-time applications in cellular communications, wireless networking, audio/video broadcasting, and navigation (GPS & GLONASS). The real-time baseband generator also supports custom or flexible modulation types including dense constellations up to 1024QAM.
Real-time generation supports creation of complex signal scenarios of extremely long durations. Satellite navigation provides an example: the MXG and EXG can generate signals representing up to 32 line-of-sight GPS/GLONASS satellites with real-time control of satellite visibility and power with up to 24 hours of simulation