luc wrote:
is it possible to have more than one NMEA input to the GPS?


NMEA 0183 is single sender, multiple listeners. So any listener ("INPUT"
) MUST NOT be be connected to two or more senders.

So the answer is yes; you can connect more than one NMEA input to your
GPS NMEA output.

However, as Meindert's webpages show so clearly, there are issues when
one of the manufacturers has not kept exactly to the standard (which a
lot do).

One obvious way to violate the standard is to tie in the GPS output,
some real NMEA inputs _and_ a RS-232 input port on a laptop. The RS-232
port violates the electrical spec of NMEA, and your results might go
either way (works or not; or even worse: works some of the time).

This mess is why there are NMEA multiplexers: to get multiple talkers
sending data to the listener, and to translate NMEA into/from
RS-232/USB/Bluetooth.

--
Kees