I have been testing a beta version of GPS-Logit that can receive data from a U-blox based receiver via Bluetooth.

Development of new GPS devices for our sport is focusing on using the new U-Blox8 GPS chips. These have been shown in tests by Manred Fuchs to be extremely accurate for Doppler speed (Up to approximately 10 times better than GT-31.GW-52!!!)

The U-Blox GPS chip has two big advantages over other potential chips.

1. It has speed accuracy estimate data in the .ubx binary output sentences.

2. It can be clocked at up to 18Hz, and tests have shown speed accuracy values for 10 seconds of around 0.02Kt!

With this in mind I dug out a Wintec G-Rays1 BT GPS receiver I bought way back in about 2007. This uses the older U-Blox6 Chip but can output binary .ubx data at 10Hz.

At the time I bought it, Roo and Chris Lockwood were experimenting with pairing it with Palm Pilot PDA's and logging the data to them. I never did get a PDA so it sat in my drawer almost unused up until now.

When Manfred released GPS-Logit, Roo and I asked him if it was possible to program GPS-Logit to accept the U-Blox .ubx data and he very kindly responded but sending us a test version. It took me a while to get the GPS setup right but with Manfed and Roo's help I got there. To make it far more user friendly, Manfred has since programmed the App to send the GPS setup instructions to the GPS.

Here is a picture of it running with the phone. The one of the left is a later model with a slighty different U-Blox GPS chip in it. So far I have not been able to get .ubx data out of it, but it is only good for 4Hz anyhow. Still working on that one.



Here is my track map from last Saturdays session. (not posted to GPS-TC but I did upload it to KA-72 after converting it to .sbp format):



The interesting thing is that GPS-Logit worked perfectly well as normal in my H2Oaudio waterproof arm bag. The GPS dongle was positioned inside my helmet as is my normal practice. Gps-Logit (Beta) has drop down menus to select the Hz rate and the Type of U-Blox chip (U-Blox 6, 7 or 8). The screen update rate is still fixed at 1 second and the speed speech is also set at one second, or optionally, slower.

Unfortunately, I got to the Inlet and found I had left my other GPS's at home. I could not be bothered driving back for them after rigging up, and knowing this would not be a super session I just went with the single system. That means I don't have any side by side on water GT-31/GW-52 data to compare it with yet.

GPS-Results:



The eagle eyed among you will notice that the 'SDOP' +/- figures are slightly higher than typical GT-31/ GW-52 values. I think this is due to the smaller antenna in this old device and possibly the older model GPS chip. They are slightly lower values than we got from Manfreds test GPS using the same chip but possibly a better antenna at Luderitz. In those tests the GT-31 and .UBX error values were very similar and very consistent with the Photo timing gear.



I am eagerly awaiting a new test device from Raymond based on the latest 18Hz U-Blox chip.

The point is that with data input from a high quality GPS receiver that include 'SDOP' data, GPS-Logit becomes an easily accessible and potentially GPSTC acceptable alternative. All the great visual and audio feedback is there with very accurate and reliable data.

PS. Unfortunately, the Wintec G-Rays1 is long out of production.

Full credit to Roo for his ground breaking early work on working out that this dongle could be teamed up with a external PDA and making it work.