||A combined split-beam, broadband, multi-frequency echosounder used for fish tracking, counting, behaviour analysis, species size and discrimination. It provides the combined capabilities of the 2100A, 2100B and 2100C models in a single unit. It can be used with Echoview (compatible with Simrad) and Matlab software, and the sonar system and processor exist in a single unit. In split-beam mode, it utilises an ethernet interface which enables multiple sonar systems to be networked together into a single system. It comes with a 30m cable with an extension to 100m available. In broadband mode the 2100C has a 6 degree conical beam operating at a frequency of 135 -200 kHz as a sweep waveform, and has a spatial resolution of 1.2cm. In split-beam mode, the 2100C operates at 175 +/- 10 kHz as a continuous waveform. In multi-frequency mode, the 2100C operates at 3 non-overlapping frequencies between 135-200 kHz as a continuous waveform.