The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Fisheries management agencies are in need of better technologies to monitor the runs of migratory species in free-flowing rivers. This paper describes a long-pulse 420 kHz riverine Doppler sonar designed to detect upstream migrating fish in shallow waters and to reject false targets and large reverberations from the surface and bottom. The use of Hanning-shaped long pulses (30 msec) results in good spectral separation between reverberations and Doppler-shifted echoes from upstream migrants. A correlation detector rejects certain classes of false targets by comparing shapes of the transmit pulse and Doppler-shifted echoes. The correlation detector also improves the system's range resolution. In field tests the system has provided an accurate run timing index of the spring 1983 sockeye salmon run on the Quinault River in Washington State. Current research includes investigating bistatic configurations for monitoring fish passage through specific regions and the use of echo integration techniques to sum the total energy in the received signal.