Abstract

This paper estimates accuracy of the open loop tracking of the tropospheric radio occultation signals by means of numerical simulations. Each error source such as: downsampling and integration in receive, thermal noise, the upsampling in postprocessing, deviation of the mean frequency of the samp... Show moreThis paper estimates accuracy of the open loop tracking of the tropospheric radio occultation signals by means of numerical simulations. Each error source such as: downsampling and integration in receive, thermal noise, the upsampling in postprocessing, deviation of the mean frequency of the sampled signal from zero, the length of the recorded signal, pseudo random modulation, is studied separately. The effect of each error source on the retrieved refractivity is demonstrated by use of the radio holographic method (canonical transform). This allows understanding of which error sources are dominant. Overall, the open-loop tracking of "worst case" tropospheric radio occultation signals result in sub-N unit rms refractivity retrieval errors with 100 Hz sampling and, in most cases, with 50 Hz sampling, when the signal to noise ratio (in 1 Hz band is ≥ 700. Show less