mpourdas wrote:but I do not understand "why".
Here is what I may understand (which may not be much) of the "set messages" situation.
Primo (and iGo), by default, may automatically adjust the communication rate of the GPS port based on calculated delays and other data received from satellites (the "messages")--comparing one satellite 'hookup' with another and so on--to try to establish a pattern of synchronization so that navigation can be more reliable.
Basically, with the set_messages=0 entry in sys.txt, this automatic adjustment is turned off, and the communication rate (baud) remains static as it is first detected by Primo/iGo or at the specific rate set in sys.txt (which is typically not necessary any more since Primo does a pretty good job of detecting just about everything by itself on
most[color="#FF0000"]**[/color] devices).
[color="#FF0000"]**[/color] There are always exceptions to this.
It is POSSIBLE (and this is only a guess!) that your particular WayTeq is more 'sensitive' to any such adjustments to the com port, and it loses track of some things...something like "Altitude" may be a lower priority feature since it does not necessarily have any bearing on accurate navigation, so that is dropped in favor of location accuracy.
That it works for you is fantastic..and an excellent FIND by you, but it may or may not solve similar issues on other devices.
But at least it is now something people who have altitude issues can TRY since it really should do no harm UNLESS it also starts to affect navigation accuracy...it
may, on
some devices.