SALMON COUNTER WITH SEPARATE KING SALMON TABULATOR

摘要

ABSTRACTA sonar fish counter, primarily for counting salmon migrating in streamsand for providing a separate count of king salmon, includes a narrow beamwidthside-scanning sonar transducer directed to insonify a volume of water in thestream directly above a mechanical beam which serves as an artificial bottom.The transducer transmits pulses of short duration such as 100 microseconds atregular intervals. After a delay following a transmitted pulse, a receiver isenabled to receive echo signals from any fish crossing the artificial bottom.During the period the receiver is enabled, a ring counter separates the returnechoes on the basis of the return time from respective sectors of the bottomstructure, and these returns are separately counted for each sector so that thecounts may be displayed or printed separately. To deal with unusually highcounts which may indicate that long term debris which has fastened to the beamor peak periods of fish migration, a counter arrangement is provided whichcounts all received echoes on a sector-by-sector basis and responds to apredetermined high count in any sector by either disabling the sector for a periodor by providing a special print character which the operator may determine asrepresenting either debris or a high fish count (as during the peak of migration).A discrimination circuit connected to the receiver separates the return pulseswhich are of unusual length, siuch as those over 300 microseconds, and suppliesthem to a separate counting structure since such elongated pulses represent kingsalmon. The counter and display means may then provide counts of all salmon bysector (across the artificial bottom) plus a separate count of king salmon plus atotal. These totals may be recorded and the counter reset at any desired timeinterval, such as each hour.