> ## Documentation Index
> Fetch the complete documentation index at: https://data.avert.ldeo.columbia.edu/llms.txt
> Use this file to discover all available pages before exploring further.

# Instruments

> GNSS instruments in the AVERT network

AVERT GNSS stations use **Tallysman VeraChoke 6100** antennas paired with **AlertGeomatics Resolute Polar** receivers. Position data are recorded at two rates: 30 s (standard) and 1 s (high rate), though the high-rate data are only telemetered during events of specific interest to minimise bandwidth consumption.

Each antenna is protected by a radome (at Alaska sites) to shield it from the elements. The LMR-400 coaxial cable connecting the antenna to the receiver is housed in a protective conduit.

<AccordionGroup>
  <Accordion title="Receivers and Antennas">
    Tallysman VeraChoke 6100 antennas with AlertGeomatics Resolute Polar receivers. These are capable of highly precise positioning measurements across multiple GNSS constellations.
  </Accordion>

  <Accordion title="Monuments">
    Three types of monument are used depending on site conditions:

    * **Drilled, rebar-reinforced concrete pylons** — used where access to competent, unfractured bedrock is limited (e.g. OKBR)
    * **Shallow-drilled braced monuments** — the most common type, involving a central mast drilled and epoxied into bedrock with 3 additional bracing rods forming a cone-shaped structure (e.g. OKCF, CLNE, CLSF)
    * **Polar mast monuments** — used where limited solid bedrock or lava flow exposure is available and expediency of deployment is critical (e.g. CLCO)
  </Accordion>

  <Accordion title="Power and Telemetry">
    Solar arrays with battery backup, transmitting data in near real time via radio links to hub sites with satellite or cellular uplinks.
  </Accordion>
</AccordionGroup>