The best echo sounder for a river survey is the one that meets the project’s depth range, coverage and quality-control requirements. A single-beam system records depths along survey lines; a multibeam system measures a swath. Dual-frequency is a separate characteristic, not another name for multibeam.
For a TOKNAV system, start with the intended deliverable, then select the sounder, positioning equipment and vessel together. Our TBoat hydrographic survey solution connects these choices into one field workflow.
Single-beam, dual-frequency or multibeam?
Single-beam: depth profiles along planned lines
A single-beam sounder is a practical option when the specification calls for profiles or line-based measurements. The gaps between lines are not directly measured: do not assume that a single-beam survey proves complete bottom coverage. Set line spacing and independent checks around the project specification.
Dual-frequency: two acoustic channels
The SDE uses 200 kHz and 20 kHz channels. Compare returns with the survey objective and bottom conditions in mind. A difference between channels is not, by itself, a verified sediment-thickness measurement; interpretation and validation are still required.
Multibeam: swath bathymetry
TMBES is a 400 kHz multibeam system, not a portable dual-frequency sounder. Swath acquisition requires attention to sound speed, installation offsets, timing and vessel motion as well as GNSS positioning. The usable coverage depends on the environment and quality criteria, not simply the maximum advertised swath.
TOKNAV echo-sounder comparison
| Model | System type | Published depth range | Selection consideration |
|---|---|---|---|
| TSBES | Single-beam | 0.5–200 m | Line-based sounding; published beam angle 8°; LAN and RS-232 interfaces. |
| SDE | Dual-frequency single-beam | 200 kHz: 0.3–200 m; 20 kHz: 0.5–600 m | Published beam angles: 7° at 200 kHz and 20° at 20 kHz. Check the channel and transducer selected for the task. |
| TMBES | 400 kHz multibeam | 0.2–150 m | Published beam widths: 2° along-track and 1° across-track; 512 soundings, with an optional 1,024 configuration. Confirm the integration package. |
These are equipment specifications, not a guarantee of final survey accuracy or safe operation at every listed depth. Confirm the current model, transducer, installation and operating conditions with TOKNAV before procurement.
Do not confuse depth accuracy, resolution and position accuracy
Depth resolution describes the measurement increment; it is not the same as depth accuracy. GNSS RTK accuracy describes positioning and must not be copied into a table as echo-sounder depth accuracy. Final bathymetric uncertainty also depends on sound speed, draft, water-level or vertical-reference corrections, motion and processing.
For example, the TMBES datasheet lists 0.75 cm depth resolution. This should not be presented as 0.75 cm final survey accuracy. Similarly, an RTK horizontal specification does not establish the accuracy of the riverbed elevation.
Five checks before ordering a river-survey system
- Define the deliverable. State whether you need cross-sections, a surface model, coverage verification or repeated monitoring, and record the required coordinate and vertical reference systems.
- Record the site conditions. Include minimum and maximum depth, access, current, vegetation, obstacles and launch restrictions. Treat advertised instrument depth range separately from the vessel’s safe operating limits.
- Select the positioning workflow. Confirm local base-rover or network corrections, communications and independent control checks. Our VRS versus RTK base-station guide explains the correction-path decision.
- Plan installation and quality control. Document transducer draft and offsets, time alignment, sound-speed procedures and water-level or vertical-reference handling. Use appropriate check lines and investigate disagreement before accepting the data.
- Confirm data handover. Agree software compatibility, raw-data retention, processed outputs and review responsibilities before the crew leaves the site.
Choosing a TBoat platform
Selecting the vessel is a separate decision from selecting the sounder. Review payload compatibility, transport, launch arrangements and field support through the TOKNAV USV product range. The TBoat10 versus TBoat20 selection guide helps organize these questions.
Customer photographs show equipment use and preparation, but they do not establish a project’s measured accuracy, survey area or acceptance result unless those details are documented. We do not use photographs as a substitute for survey evidence.
Frequently asked questions
Is multibeam always better than single-beam?
No. Match the instrument to the coverage and deliverable required. Multibeam can support swath coverage, but it introduces integration and processing requirements. A line-based specification may call for a simpler single-beam workflow.
Will an RTK fix guarantee accurate water depths?
No. RTK positioning is one part of the system. Sound-speed, installation, timing, draft and vertical-reference errors must also be controlled.
Can one specification describe all three TOKNAV sounders?
No. TSBES, SDE and TMBES are different systems. Compare the correct model and channel, and distinguish instrument specifications from final survey performance.
For broader workflow context, see NOAA’s hydrographic standards and requirements. Apply the standards required by your own project and jurisdiction; this guide is not a certification of compliance.
Request a river-survey configuration
Tell us your country, expected depth range, required coverage, positioning method and output format. We can then review a suitable sounder and TBoat configuration without assuming that one package fits every river.