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In addition to buoyancy capability, the solar towers offer incrementally larger solar panels for projects with a heavier power load. The bigger the buoy, the more batteries can be stored in the data well for reserve power. The instrument hole diameters are 4 inches, 6 inches and 8 inches respectively in the three large buoy models.

When measuring near the surface, water quality sondes can be housed inside a slotted deployment pipe that is threaded directly to the bottom instrument well on the buoy hull. This allows instrument access for periodic cleaning and calibration without having to pull the buoy out of the water. If the project requires measurements at depth or at multiple depths, NexSens offers instrument clamps and mooring cages for mooring lines, as well as bottom platforms when sondes need to be bottom referenced instead of surface referenced.

For customer integrations, cables can be run through one of six ports on the passthrough data well lid and secured with a supplied cable gland. The backside of the cable gland should be filled with epoxy or sealant to prevent water ingress. Alternatively, NexSens can supply a waterproof bulkhead connector with mating pigtail for splicing with user-supplied sensor cables. This allows for a quick disconnect of the cable at the lid. When using an X2-CB or X2-CBMC data logger on a NexSens integrated system, all supplied sensor cables are terminated with mating UW plug connectors or MCIL-8-FS connectors.

The mounting for an acoustic Doppler current profiler (ADCP) is instrument-dependent. NexSens offers several ADCP mounts for Nortek instruments, including the Aquadopp and Signature Series ADCPs. The mounts must be designed in such a way that the acoustic beams are unobstructed by the buoy and mooring. Custom mounts are also available based on project-specific needs. Contact info@nexsen.com for more details.

NexSens data buoys are designed to simplify the connection of a wide variety of measurement sensors for weather, water quality, water current, waves and solar radiation. When combined with NexSens data loggers, these buoy-based sensors display measurement results online that are accessible to project staff and collaborators. Weather station parameters include air temperature, relative humidity, barometric pressure, wind speed, wind direction and more. Some advanced weather stations also incorporate GPS, tilt, accelerometer & compass sensors. Terrestrial and Underwater PAR sensors measure photosynthetic active radiation. Water quality sondes measure temperature, conductivity, depth, dissolved oxygen, pH, ORP, total algae (phycocyanin and chlorophyll), turbidity, and fluorescent dissolved organic matter (fDOM). The sondes also output several calculated parameters like salinity, specific conductance, total dissolved solids (TDS) and total suspended solids (TSS). Water current sensors used with data buoys are typically multi-beam acoustic doppler based and and measure currents, turbulence, wave height and wave direction. Wave data (height, period, direction) can also be measured using inertial-based sensors mounted on the buoy hull.

Nexsens offers custom mounts for most industry met sensors including Airmar, Lufft, Vaisala, Gill and YOUNG. Sensor extensions are available based on the height of the sensor in relation to the water's surface. It is necessary to integrate a compass with any buoy-based met sensor to correct for wind direction due to buoy movement.

NexSens has a power budget algorithm to input variables like telemetry methods, measurement frequency, transmission frequency, instruments connected, months deployed, and location for any factory integrated system. With those variables, it is quickly determined whether a given buoy platform will have sufficient solar charging and battery reserve for autonomous deployment.

The X2 data logger is directly compatible with sensors that have a native SDI-12, RS-485 or RS-232 output. The data logger can also support analog sensors using an analog-to-digital adapter (PN# mV-RS485) or tipping bucket rain gauges using a pulse-to-digital adapter (PN# RAIN-RS485). There are three tiers of sensor compatibility with the X2 data logger: Tier 1 Sensors have auto-detect, which connects sensors automatically without programing -- no prior setup required. Tier 2 Sensors must be configured with manufacturer-specific software before connecting to logger. Prior to data logger connection, customers can specify preferred types of parameter outputs. Tier 3 Sensors can be added through the creation of a user-defined script. The script is written in Lua and utilizes NexSens-created functions to simplify programming. As long as the sensor communicates using SDI-12, RS-485, or RS-232 and can be powered from a 12V supply, it should be compatible with the X2 data logger. See the complete list of supported sensors and associated tiers HERE.

The X2-CB with integrated Wi-Fi can connect to Wi-Fi hotspots with a range of up to 250 feet using the external antenna. This allows data to be pushed up to the WQData LIVE web datacenter without the added costs of cellular/satellite service fees or radio base station hardware. Given the limitations of broadcasting a Wi-Fi signal over open water, this is generally only feasible in near-shore applications (ponds, industrial sites, etc.).

All of the X2-CB data loggers include an external antenna specific to the integrated modem (Wi-Fi, cellular, satellite or radio). Each type of antenna threads to the lid of the logger using an N-Style RF connection. Antenna extension cables are available for situations where the antenna needs to mount up higher on the solar tower, which is common for radio and Iridium satellite applications.

Changing measurement or transmit frequency can be done remotely using the WQData LIVE Web Datacenter or through direct PC connection using the UW6-USB-485P adapter and CONNECT Software.

The X2-CBMC data logger is designed for offshore marine applications and difficult freshwater environments, while the X2-CB data logger is meant for lakes and other inland bodies of water. The X2-CBMC uses MCBH/MCIL wet-mate sensor/power connectors and a pressure relief valve for battery outgassing compared with UW plug/receptacle connectors and a passive battery vent on the X2-CB.

The X2-CBMC (and all X2 data loggers) allows each sensor to have its own measurement interval if desired. Alternatively all sensors can measure at the same interval.

Customers can send in sensor cables to be terminated with an 8-pin female wet mate connector (PN# MCIL-8-FS-X). Alternatively, NexSens can provide pigtail cables terminating in bare wires for the customer to splice with their existing cables (PN# MCIL-8-FS-1).

The X2-SDL data logger is available as a standalone package that can be fully submerged for extended periods of time. Mounts are available for underwater structures and instrument cages. For applications requiring wireless telemetry, the logger is typically secured above water on a fixed structure (stream bank, piling, etc.) or housed inside a CB-50 data buoy.