when etek was making these modules, the 2nd port for DGPS wasnt working in the current firmware 1.8xseomthing......
however it can be used to receive RTCM updates if you set it to that!!!
not sure what would come out of the port in WAAS mode (if anything)....
remember DGPS RECEIVES RTCM information... so yah youd need a DGPS receiver to get those beacon signals and send it to the 2nd serial port.
however in some cases WAAS is more accurate than DGPS!
just use WAAS if you got it. and leave the 2nd port alone.\
what cases?
the distance you are from the DGPS transmitter / beacon... it does matter!!! accuracy affects that.
and DGPS RTCM beacons / and transmitters arent located everywhere.. in the US the coast guard runs them along the coast for naval use.... some other systems are into play.
but you need a separate receiver to receive and decode those transmissions.
i suggest you do a google search for DGPS and read up on the topic and see if DGPS is even available in your area.
you are better off using WAAS.
i dont know the current status of sannav's tinkering with the firmware or if they have it fixed, but last i heard the DGPS RTCM updates werent working.
anyways in 2 years when L1C and L2C satellites are launched and the GPS system is updated we will all have 4 inch accuracy.
ALL YOUR BASE ARE BELONG TO US!!!
hahahahah...
yah pretty scary huh.
its coming.