Table 3.

Summary of less expensive PA signal detection methods.

Type	Central frequency (MHz)	Bandwidth (%)	No. of elements	Model/company	Ref.
Single element/multi element PACT	2.25, 5	70	2	V323-SU, V309-SU, Olympus NDT	[4]
	3.5	88	1	V383, Panametrics	[16]
	10	100	1	XMS-310, Panametrics	[106]
	5	75	16	ISL-0504-GP, Technisonic	[98]
Linear array PACT	7.5	100	128	SL3323, Esaote	[58,104]
	7	85	128	LA0303, S-sharp	[107]
	10	80.9	128	PreXion Corporation	[67]
	5	60	128	L7-4, ATL/Philips	[76]
	5	NA	320	EZU-PL22, Hitachi	[108]