About: http://webisa.webdatacommons.org/449790304

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Two similar segments or lengths of said signals may thus be compared for amplitude or frequency variations by the means provided and the resulting differences in signal variations indicated by apparatus such as illustrated.
http://www.w3.org/ns/prov#wasQuotedFrom	google.co.uk