Steps: 1. Switch the GPS to SiRF mode Most "PDA" GPS receivers use a SiRF Chipset and while it can be programmed in NMEA mode, the easiest (and the way GPSTweak does it) way to do it is in SiRF mode. You can use GPSTweak to switch to SiRF but I prefer to do it with CE Monitor, as explained here. I've found that GPSTweak will operate faster if the baudrate is set to 38,400. Then exit CE Monitor.
2. Poll and Activate SBAS a. launch GPSTweak b. Go to Setup/Port Settings - Select the same COM port as in CE Monitor - Select SiRF - Select the baudrate set in CE Monitor - Click OK c. Go to Setup/Connect, you will see "SIRF: Entering decoding thread" d. Go to Command/Poll WAAS/EGNOS Status and you will see the current SBAS status in "Source". It can be "Serial" or "External RTCM Data", i.e. SBAS is off or "WAAS/EGNOS", i.e. SBAS is active. e. Now go to Command/Toggle WAAS/EGNOS - this will activate SBAS and launching that command again will de-activate SBAS, regardless of the status seen in d. f. Now Poll the status again to check that the settings have been registered.
3. Switch back to NMEA/4,800 Following the instructions in 1. above, switch back to NMEA/4,800, the "universal" data format used by navigation software
Using SBAS: Your GPS will now try to use SBAS satellites to correct the GPS position calculated with the "standard" GPS satellites and send that data to your software. At this time, only PocketMap Navigator (icon) and the free VisualGPS CE (DGPS on line at the bottom) display SBAS status *.
* With other programs you'll have to record (if they allow this) the NMEA stream and look at message#6 in the GGA message to determine whether you were getting a SBAS feed - (0 means no fix, 1 means GPS fix and 2 means SBAS fix)