Hi - I was wondering, can somebody explain how DGPS works in the lassen IQ modules? Do you have to use a seperate DGPS receiver and feed that into the lassen iq? Or something else? I couldn’t find much of anything regarding use of DGPS in the lassen iq datasheet. Thanks!
The way I understand it, you almost always need an external DGPS receiver. The standard DGPS signal is sent in the 300KHz band somewhere, and receiving that over the same RF front end that processes the L-band GPS sat signal is going to be extremely hard. I say almost because there are commercial units out there that can receive them all in one box, but they’re usually pretty expensive (an order or magnitude more than the modules, plus or minus).
Besdes, with WAAS on something like the Laipac PG-31, and SA off, do you really need DGPS?
-dave
Hmm - so there are no compact gps modules that have a built in DGPS receiver? That is unfortunate.dpaton:
The way I understand it, you almost always need an external DGPS receiver. The standard DGPS signal is sent in the 300KHz band somewhere, and receiving that over the same RF front end that processes the L-band GPS sat signal is going to be extremely hard. I say almost because there are commercial units out there that can receive them all in one box, but they’re usually pretty expensive (an order or magnitude more than the modules, plus or minus).Besdes, with WAAS on something like the Laipac PG-31, and SA off, do you really need DGPS?
-dave
About the PG-31 - so it supports WAAS and EGNOS - does that mean it’s taking data from both and combining them for the most accurate possible position fix? Or do you just switch between them?
Thanks for your help!
Maybe. DGPS mostly only works if you're less than 100 miles or so from a coastline or the edge of a major body of water. Coverage across the rest of the US is inconsistent:NleahciM:
Hmm - so there are no compact gps modules that have a built in DGPS receiver? That is unfortunate.
http://www.navcen.uscg.gov/dgps/coverag … verage.htm
Plus, with the availability of WAAS you can get an accurate fix to within 2 meters. The Garmin GPS-V in my dad’s car tracked us to which lane we were in on the highway on a recent road trip (landmark snapping was off, thank you very much 8) )
NleahciM:
About the PG-31 - so it supports WAAS and EGNOS - does that mean it’s taking data from both and combining them for the most accurate possible position fix? Or do you just switch between them?
EGNOS is a European version of WAAS, more or less:
http://www.esa.int/esaNA/GGG63950NDC_index_0.html
http://www.garmin.com/aboutGPS/waas.html
Your receiver will only use 1, unless you have a really amazing antenna.
-dave