Overview; Single Pulse Versus Multi Pulse Performance - Edgetech 4200 User Hardware Manual

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The EdgeTech 4200 Series High Definition Dual-frequency Side Scan Sonar System is a frequency-
modulated (FM), dual-frequency side scan sonar that uses EdgeTech's proprietary Full Spectrum "chirp"
and Multi-Pulse technologies to generate high-resolution side scan imagery at longer ranges than
conventional continuous wave (CW) systems.
The 4200 Series is available in single-pulse (SP) and optional multi-pulse (MP) configurations, and in three
dual-frequency choices: 100/400 kHz, 300/600 kHz, and 300/900 kHz. In both the SP and MP
configurations, the two frequencies are transmitted simultaneously. In the MP configuration, multi-pulse
operation doubles the repetition rate. This increased rate of repetition allows for increased tow speeds
of up to 9.6 knots, while still meeting the NOAA and IHO-44S Shallow Water Survey Specification of three
pings on a 1-meter cubed target at 100 meters.
The optimum configuration and frequency choices are dependent on the application. In both
configurations, the frequencies are transmitted as linearly-swept, wide-band, high energy acoustic pulses.
The received echoes are processed into high signal-to-noise (SNR) images that can be directly displayed
as shades of gray or one of many varying color palettes on a computer monitor and printed on a
continuous feed thermal printer. The data can also be stored in real-time onto a large capacity hard drive
and archived onto a DVD.

1.1 Single Pulse versus Multi Pulse Performance

Both the single-pulse (SP) and multi-pulse (MP) configurations of the 4200 Series High Definition Dual-
frequency Side Scan Sonar System provide dual, simultaneous frequency operation, and are designed to
accommodate the integration of optional sensors. Both configurations also provide excellent signal-to-
noise performance, resulting in superb data that are reliably transmitted digitally over coaxial cables as
long as 6000 meters.
The MP configuration allows two pulses to be in the water during each ping cycle instead of one in the SP
configuration. This essentially breaks the sound speed barrier by allowing twice the conventional survey
vessel speeds to be used for the same coverage. At conventional survey speeds, twice the data density of
an SP configuration can be achieved with an MP-fitted system due to the two pulses. These benefits of
MP technology translate into better target detection and classification capabilities. And the use of
standard chirp technology makes both the SP and MP configurations far less expensive than similar
performing high-speed multi-beam systems.
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