UniData Communication Systems Starflow QSD Manual page 30

Manual – Starflow QSD Model 6527B and 6537A
Once the Doppler Spectrum Tool has been opened, the Doppler signal will be shown on the graph. In
the above example the graph is well defined and there is a definite "Peak" to the signal. The RSSI and
Qutl (spread) is also displayed giving further confirmation of a good Doppler signal.
The above example is a poor signal as the signal strength (RSSI) has halved and the Qutl (Spread)
quadrupled from the previous (good) signal. The graph peak is not well defined and has flattened out
indicating the instrument is having difficulty identifying a good median velocity. It is also seen that the
velocity is now showing a –ve value and yet the instrument was placed in a forward flowing water
course.
In this case the Starflow QSD instrument had an obstruction placed in front of the instrument causing
turbulence around the ultrasonic eyes.
Unidata Manual - 6527B and 6537A Starflow QSD User Manual 17 01 2020.docx Page 28