Acquisition-Level Optimization of Split-Spectrum TEC Observability in L-Band InSAR

Split-spectrum ionospheric correction is performed after acquisition, yet its precision is partly set by acquisition-dependent bandwidth, subband signal-to-noise ratio, and frequency separation. We define the dimensionless observability index as OI=σTEC,obsσTEC,pred and optimize SAR acquisition and split-spectrum method (SSM) parameters jointly within LT-1-informed hardware bounds and explicit study assumptions while enforcing identical constraints on swath, resolution, noise-equivalent sigma zero, ambiguities, duty cycle, average power, and data rate. A public-parameter reference (B), a conventional SAR optimum (T), and an ionosphere-aware design (IA) are evaluated with the same processor. With the T acquisition fixed, SSM-only optimization lowers predicted TEC uncertainty by 7.16%, whereas the complete system-processing co-design lowers it by 11.66%. At a differential-TEC standard deviation of 0.821 TECU, IA reduces TEC RMSE by 7.37% and corrected phase/line-of-sight RMSE by 11.09%. Across non-thermal coherence values of 0.65–0.95, its predicted advantage remains 8.74–14.27%. A measured 80 MHz UAVSAR SLC pair recovers a controlled 0.821 TECU screen with 0.026 TECU RMSE and 0.9998 spatial correlation. Thus, TEC correctability is partly an acquisition property and can be improved without relaxing conventional SAR requirements.