Updating my gps
The emap, 76 family, and etrex store waypoints in 3 dimensions by including altitude. The 76 family will also store depth data for water if an optional depth sensor is attached.
When you first create a new waypoint the unit will automatically assign it a name.
Periodically, when the tracker receives an uplink it will reply with a telemetry string so that the gateway can upload the balloon position to habitat as usual.
The string is standard except for the addition of some status information about the uplink.
Assuming the messages arrives intact, the tracker replies with an ACK; any other reply (or no reply at all) results in the message being re-sent.The following diagram shows how this is achieved in software: The Lo Ra gateway is the standard release with modifications added to provide a server socket on a specified port, to which any network terminal program (e.g. In this case I have written a simple terminal program, in Delphi, that screen-scrapes the terminal window and sends the contents to a Python script, which then updates a web dashboard so that anyone with the URL can see what I see in my terminal program.Separately (and not shown on this diagram) another Python script updates the same dashboard with the current telemetry, using data from the habitat system.At the tracker, these messages result in those key codes being sent to the telnetd program (telnet daemon) which is an installable program on Raspbian.
That program provides a regular command interface – same as a login on a Pi using a keyboard and monitor – and any responses to those key codes are sent back from telnetd to the tracker program, where they are included in messages sent back to the ground.
These database waypoints are discussed in the chapter on databases. On most unit they must be no more than 6 characters long and contain no spaces but can contain any combination of letters and numbers and some punctuation.