Table 2.

Interval measurement errors and signal loss level in the FHR_U for two AF repetition cycles K (25 and 250 ms), using the PF with different window widths S or without PF. Four combinations of US signal bandwidths and four envelopes were considered.

K (ms)	S (ms)	$\overline{\left|\Delta {\mathbf{T}}_{\mathbf{i}}\right|} \left(\mathbf{ms}\right)$				FHR_U Signal Loss (% )
		100–600 Filter 100	100–600 Hilbert	300–600 Filter 50	300–600 Hilbert	100–600 Filter 100	100–600 Hilbert	300–600 Filter 50	300–600 Hilbert
250	–	1.95 #	1.94	1.91	1.91	2.01	1.87	2.82	2.56
	125	3.17	3.02	3.04	3.03	6.97	6.74	6.13	6.84
	250	2.14	2.12	2.08	2.07	1.17	1.07	0.75	0.88
	500	2.02	2.02	1.99 1	2.00 2	0.78	0.79	0.56 1	0.56 2
25	–	1.96	1.94	1.89	1.90	1.92	1.84	2.81	2.43
	125	3.00	2.97	3.00	2.91	6.28	5.98	6.39	5.97
	250	2.11	2.1	2.09	2.07	1.39	1.28	0.91	0.91
	500	2.02	2.02	1.98 3	1.96 4	0.8	0.79	0.57 3	0.59 4

^# mean value ^1–4 four parameter settings to be used in further experiments.