The authors summarize methodology and survey results of SNR and BER estimation for HF medium-range communication links over the Estonian mainland. HF propagation and noise environment were monitored since recent years in order to provide support to military and paramilitary users. The reliability of HF data communications was tested using STANAG 4539 data modems. The vast majority of tests showed that the radio signal propagation is dominated by Rician fading, which consists of one strong LOS (Line-of-Sight) component and many weaker multipath components. Estimated values of K parameter varied within the range from 1.3 to 9. Corresponding BER curves for 8PSK signals without and with FEC (Forward Error Correction) indicated insufficient reliability of HF links encompasses relatively high level of interfering ionospheric component (K < 5).