In recent years we have worked a lof with standard devices, we realize that this standard devices will never reach the high-end specifications of Doppler GPS, but for normal day-to-day use, and the average surf-sessions this devices could be a nice alternative for some windsurfers. We are exploring the possibilities of enhancing the software of “standard” GPS-Devices. Target is to reach the current standards of GPS logging at GPS-Speedsurfing.com, so making it possible to measure at a 1 per second rate, and log the number of satellites.
In general we allow any GPS Devices that’s is capable of logging GPS Data with a sample rate of 1 per second and support the .GPX data format. Please notice that the use of .GPX format is not allowed for records, and is more suited for normal day-to-day surf sessions. The only fully approved format at this stage are the .SBN, .SBP & .UBX format.
Setting up a general GPS Device for GPS-Speedsurfing.com
- Make sure that the devices supports a 1 per second GPS Frequency Rate and store the data in .GPX format.
- Export your session to .GPX format, please follow instructions by your own manufacturer
- Import your .GPX file in GPS-Speedsurfing.com with our auto-upload feature, you can find this in the “My GPS” Section
Specifications for Hardware Vendors
We strongly encourage hardware vendors to develop GPS devices on the highest possible specifications for GPS-Speedsurfing.com. To make a GPS truly an attractive and practical alternative to the GT-31 and able to be approved for use to set official World GPS Speed Surfing Records, these are what we need (most of these are met by the discontinued GT-31).
Certification Process New GPS Devices
The GP3S GPS Certification Process for new GPS involves a series of steps to evaluate the technical specifications and performance of the potential new GPS Device.
- The first step before certification is to inform GP3S by email at info (a) gps-speedsurfing.com about the scope of the project and the objectives
- During the development process it’s crucial to inform GP3S about the progress of the project on a regular basis and share interim results of data logging in an early stage. This way we can support the development process and prevent potential rejection of the device during the final certification
- In the final stage of certification GP3S must receive two identical devices (both on hardware & software level), those two devices will be tested and benchmarked by an independent test-authority. The results of this benchmarked are decisive for official certification and approval for the use on GPS-Speedsurfing.com
The minimum requirements for an official GPS Record device are:
- The normal positional data at minimum 1hz
- The Doppler derived speed data (speed over ground) at minimum 1hz
- The number of satellites tracked for each data point
- Display current speed and max speed for a session
- Display distance travelled in a session
- Have to ability for the data recorded to be easily downloaded to a computer via a standard type of interface or post it directly by Wifi t to the gps-speedsurfing website.
- The data downloaded is in a standard format easily read by our current software (GPX, UBX or SBIN)
- Data recording at 5hz or higher, preferably up to 10hz, The units should always run with the highest possible sampling-rate since omitting points to get less data leads to aliasing artifacts in the Dopplerspeeds. Positional data can be downsampled by leaving points out, not so the Dopplerspeeds - that would only be possible after low-pass filtering the doppler-data with half the sampling frequency (Nyquist-theorem) and that is not done by the GPS-chipsets if you run them at lower sampling rates. So one would throw away essential data by omitting points leading to wrong average speeds.
- The system error estimate data produced by the GPS engine recorded in the data. We use this to determine the correction to the recorded data needed to correct the speeds to a 99.9% confidence. That is, we can be 99.9% confident that the speeds were at least as fast as what we claim. To do this with the Locosys GT-31 we were able to record the Sirf binary data in .sbn format to the memory. We also have the essential data recorded in a more compact format called .sbp.
- Data recorded in a compact Sirf binary format or similar like UBX as mentioned above instead of NMEA. NMEA-sentences do not have a field for the error of the Dopplerspeed (SDOP), the same is true for standard GPX output even though GPX is XML based and thus such a value can easily be added. However, most GPS-chipsets do not even give that important value in their binary output, only u-blox chipsets do that ever since in the UBX-format (sAcc in NAV-SOL, NAV-VELECEF, NAV-VELNED u-blox 5, 6, 7, 8; NAV-PVT u-blox 7 and 8). For Sirf-chipsets used in the GT31 that value was added later.Only GT31 / GW52 and all u-blox based GPS’s give this value in their binary output. NMEA- or GPX-output can also be programmed with these chipsets, but requires computational overhead, results in about 10-times the storage space as compared to the binary output and contains less information.”
- Battery life for recording of over 24 hrs. 24 hours is a world record category but also many of our users may want to sail for a number of consecutive days without easy access to recharging.
- Large capacity memory for at least 24 hours of logging.