Recently, alternating coded pulses have been implemented at Jicamarca for Incoherent scatter measurements. This new mode is intended to facilitate aeronomy research in the topside and protonosphere. By virtue of utilizing the full duty cycle capabilities of the radar transmitter, this mode has improved sensitivity over the conventional Faraday double pulse mode and permits multiple parameter estimation at protonospheric altitudes. The lowest useful measurements are obtained around 450 km altitude. Relative density measurements are obtained from the power measurements, and ionosonde data is needed to get the absolute values. Currently, the alternating code experiment is performed with the following parameters: IPP = 6000 km, PW = 240 km, BW= 15 km, bits per code = 16, number of codes=128 (Randomized AC codes).
More details, including error analysis and examples are given by Hysell  .