Optimize Geode for Use Under Forest Canopy

21 Nov 2023

Forest canopy can make it difficult for the Geode or any GNSS (GPS) receiver to locate satellites and provide precise geospatial positioning. This was demonstrated for the original Geode (aka GNS1). Beyond applying our general recommended settings for the Geode, the following suggestions may be helpful in such conditions.

• Reduce the antenna mask angle (such as from the default 10° to 5° or 0°) to increase the number of satellites the Geode can see. The quality of signal from low-angle satellites may be worse than high-angle satellites; however, when high-angle satellite signal is blocked, lower quality signal can be better than nothing.

• Make use of point averaging settings, if available in your app. Choosing to average a higher number of points and allowing a longer period of time between the points being averaged can provide better positioning of the final recorded point.

• Post-processing GNSS (GPS) data to apply additional corrections later can potentially provide better accuracy, even if data was recorded in poor conditions (such as under tree canopy).

• Enable Multi-GNSS. Being able to receive GPS, GLONASS, and other GNSS signals allows for more available satellites to be in view, which gives a higher chance of getting better accuracy.

• If you can receive a good signal reasonably nearby, you may be able to offset a recorded position. You could use a laser range finder to precisely find the distance of the offset.

• Although it would be difficult to find an antenna that is much more sensitive than the Geode's integrated antenna, an external antenna that could be raised higher into or above the canopy could provide better signal. An external antenna mounted on a tall pole could be effective.

• SBAS (such as WAAS), ATLAS, and other satellite-based correction services would have the same signal limitations under tree canopy as general GNSS/GPS satellites. If you can arrange a clearer view to those geosynchronous satellites above the equator, they could help.

• For the GNS3M model, having multi-frequency enabled for L1, L2, and L5 signals can potentially help, although if L1 signals are already limited then L2 and L5 signals are likely to be even further limited.

• Connecting to an RTK network using NTRIP may be difficult due to often limited internet connectivity in locations obscured by tree canopy. Also, each mount point has a limit of compatible satellites. The compatible satellites will likely also be restricted by overhead obstructions.