GPS trackers with “cache”

Some newer GPS trackers includes a cache for GPS locations. This is so that a history of the device’s track can be sent to the network if it didn’t have coverage for some time. Other devices might send an old cached GPS point if their GPS fixed failed. In both these cases the GPS location and the location where the transmission was made does not align – and these points gives the wrong impression on a coverage map.

Digital Matter Oyster/Yabby

For these devices please use the payload decoder from the TTN Device Repository as this decoder handles cached locations correctly.

Seeed T1000

“When the LoRaWAN signal coverage is weak or there is no network coverage, the device cannot receive an ack when uploading data. In this case, the data will be saved and entered the next cycle. When the device successfully uploads data at some point, it will send offline data.”

Seed T1000 documentation

For the Seeed T1000, please disable the above feature, or switch to sending without requesting ACKs.