In real-time mode, a graphical interface provides a direct instrument connection for parameter transfer and closed-loop or interactive control during signal generation. Continuous data or closed-loop testing is becoming increasingly important in the testing of several wireless standards: 3GPP LTE TDD and FDD; digital video; Global Satellite Navigation Systems; GSM/EDGE; 3GPP2 CDMA; and 3GPP W-CDMA. All these are supported by the corresponding versions of Signal Studio.
Enhancing real-time baseband generation
To support real-time mode, the MXG and EXG include a powerful internal real-time baseband generator and processor-accelerator ASIC. The baseband generator also supports custom or flexible modulation types including constellations as dense as 1024QAM.
These capabilities support creation of complex signal scenarios of extremely long durations. In satellite navigation, an MXG or EXG can generate signals representing up to 32 GPS+GLONASS satellite channels with real-time control of satellite visibility and power with more than 24 hours of simulation time (Figure 3). In DVB applications, this solution supports up to two hours of playback or continuous PN23 data sequences.
Real-time generation is especially useful during throughput testing of real-world channels. An example configuration is shown in Figure 4. In testing such as LTE HARQ, the X-Series signal generators can receive TTL-level feedback signals and reconfigure the transmission signal while maintaining the link. This enables highly realistic testing of throughput over impaired channels.
Simplifying signal simulation
The replay of an