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Yes, GPSy can work with a GPS with a DGPS receiver at the same time. This will give you < 10 meter accuracy in real-time. DGPS beacon transmitters are established along the entire U.S. coastline and most other nations are setting them up as well.
There are two main issues with hooking up GPS/DGPS configurations to your computer:
Note that in all of these schematic diagrams, Data GND of all of the units are grounded (connected) together. We skip this important detail in the schematics to simplify the diagrams.
There are several options:
This sets up the system as a dedicated DGPS configuration. You won't be able to transfer data between the computer and the GPS unit (waypoints, etc.) but it's a good configuration if all you're interested in is real-time DGPS corrected DATA
GPS data in <-----------RTCM------------------<-- DGPS data out
GPS DGPS
GPS DGPS
GPS data out -->---------NMEA-0183---------------> DGPS data in
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+--- Macintosh Data in
(Mac Data GND connects to both GPS/DGPS data GND)
(Mac Data Out left unconnected)
+--- Macintosh Data Out
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GPS data in <------------O/O------------------<-- DGPS data out
GPS DGPS
GPS DGPS
GPS data out -->-----------+---------------------> DGPS data in
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+--- Macintosh Data in
GPS <----RTCM ------------------------------------- DGPS
GPS DGPS
GPS DGPS
GPS ---NMEA-0183-----> NMEA-0183 BUS Splitter ----> DGPS
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+--- GPSy/Auto-Pilot
Note that while you use the bus splitter to split the outgoing NMEA-0183 stream to go to both the DGPS and GPSy, you take the RTCM (DGPS correction data out) of the DGPS and send it directly back to the GPS. If confused, take this diagram to your installation technician, they should be able to understand it.
GPS ------NMEA-0183---> GPSy/Mac ----> NMEA-0183 ----> DGPS
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+--<------------------------- RTCM <---------------<-----+
As far as we know, this will be a unique feature not on any other product on either Mac or PC platforms.
Our new DGPS-IP client feature in GPSy 3.30 and GPSy Pro 1.10 works by contacting Internet DGPS-IP Servers (such as dgps.wsrcc.com). These servers stream DGPS correction data in the industry standard RTCM SC-104 protocol from two server vantage points on the East and West coast of the United States. From those two servers, there is DGPS coverage of all of the United States; much of Canada and Mexico; and the western portion of Europe. We'd like to actively encourage people in Europe, South America, Africa, Oceania and Asia to also set up DGPS-IP servers so that we may have world coverage.
What DGPS-IP clients do is set up a connection through the Internet to the DGPS-IP servers and stream the data directly into your GPS unit. Most GPS units with serial ports directly accept RTCM data (set the unit to the NMEA data out / RTCM data in setting) and will immediately calculate a DGPS position. This is unprecedented accuracy, and the best thing is that it's free!
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In our testing here at the lab, accuracy of the GPS unit will go from the 100 meter accuracy of uncorrected GPS to less than 10 meters with DGPS-IP. This is accurate enough to even tell you which side of the road you are on. Of course, this accuracy is highly dependent upon the number of satellites you share with the DGPS-IP server as well as your satellite visibility (DOP) and other factors.
Obviously, to use DGPS-IP, you need a real-time connection to the internet. Most of our customers seem to either be using DGPS-IP in a stationary location (to get high-accuracy position data through averaging) or are using some form of mobile internet connection such as cellular PPP or Ricochet.
Some tips:
Copyright (C) 1997-2007 by Global Mapping Systems and Karen Nakamura. All rights reserved. GPSy® and GPSy.COM® are registered trademarks and GPSy ProTM and GPSyLinkTM are trademarks of Karen Nakamura. All other trademarks are the property of their respective owners. Mention of a third-party's product does not represent endorsement of or by that product.
This page was last updated on September 29, 1999.
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