Fig. 13
From: Software-defined radio-based HF doppler receiving system
Frequency bias in Doppler frequency. a Doppler frequency obtained at three digital receiving stations (CHB, FJS, and AWJ), which were sampled at 03 UT (12 JST) for two months from 01 November 2020 to 31 January 2021. b Doppler frequency obtained by the receivers under a receiving test in the laboratory for deployment to five stations (SAR, ORI, CHF, FJS, and KOK)