Spotter 3’s High Data Rate (HDR) mode sends 1000x more data at a fraction of the cost

Accessing the data collected by marine sensing devices is traditionally an expensive process. Typically, data transmission occurs via satellite, a powerful solution that is limited by high costs; to send 200 kb worth of data via Iridium, for example, expenses can exceed $100.

Spotter 3, the third generation of Sofar’s Spotter buoy platform, offers a new alternative. Each device is outfitted with an onboard cellular modem, which makes it possible to transfer data using existing global cellular infrastructure. These cellular transfers enable Spotter 3 to send 1000x more data at a fraction of the cost via the new High Data Rate (HDR) mode. In nearshore environments, this:

• Unlocks high-bandwidth use cases that were previously impractical due to high satellite data transfer costs. HDR allows for flexible control of spectral processing and makes it possible to send full wave displacement time-series data to the Sofar backend.
• Reduces reliance on Spotter’s onboard SD card. With more data sent via HDR, less effort and time needs to be spent physically recovering the SD card.

High costs constrain Spotter data transfers via satellite 

Prior to the introduction of HDR, Spotter data could only be transmitted via satellite. To keep costs reasonable, the amount and type of data transmitted is regulated: 

• To reduce the size of the satellite data transfer, the data is first pre-processed and compressed to meet the constraints of the preset Spotter data mode: Waves: Standard, Waves: Partition, Waves: Spectrum, or Track.
• In each data mode, the full time-series of the Spotter’s movement (displacement data) is stored on the onboard SD card. To analyze and process the stored data, the SD card needs to be physically retrieved from the deployed device.
• The fastest data update rate possible, excluding Track, is 30 minutes in Waves: Standard.

This approach to data transmission remains effective, particularly in the open ocean where cellular infrastructure is nonexistent. For nearshore applications, however, HDR is a more powerful and cost-effective solution.

How HDR transmits more data at a faster rate

Cellular telemetry dramatically lowers transmission costs, eliminating the need to pre-process and compress Spotter data into preset data modes. Using HDR, you can transmit full time-series data directly to the Spotter dashboard and API:

• First, HDR sends compressed and pre-processed time series data over cellular to Sofar’s backend servers.
  
• The data’s absolute location history is then reconstructed and filtered to generate the wave displacement data that previously would have been stored on Spotter’s SD card.
  
• That data is propagated across the three Wave: data modes (Waves: Standard, Waves: Partition, Waves: Spectrum ), giving you instant access to a more comprehensive dataset at no additional cost. HDR samples at 2.5Hz and processing rates can be configured to as short as 5 minutes.

By shifting the computational load from Spotter’s onboard computer to unconstrained servers on land, HDR increases your access to data and enables more flexible and powerful analysis techniques.

How to enable HDR

If you have a Spotter 3 that is using firmware version v2.3.0 or higher, you can enable HDR mode. To do so, please email us at support@sofarocean.com.

Once enabled, the HDR processing rate can be configured on the Spotter dashboard. Data sent using HDR can be accessed via the Sofar API (see documentation) or by downloading .CSV files from the Spotter dashboard.

HDR is a significant step forward for Spotter’s ocean data collection and transmission capabilities. New analysis options, such as spectral and time partitioning, different tuning and filtering capabilities, and the removal of spikes in low energy conditions, are forthcoming.

If you have feedback about HDR, ideas for future features, or any questions, please feel free to send us an email at support@sofarocean.com.