GPSCAN MK2 50 Hz vs GPSCAN 100Hz

Our GPSCAN 100Hz is no longer available due to poorer performance against GPSCAN MK2 50Hz. Below is the reasoning why:

	GPSCAN 100Hz	GPSCAN MK2 50Hz	Why this is important?
Supported systems	GPS ONLY @ 100Hz	Concurrent GPS+GLONASS+GALILEO+BEIDOU+QZSS systems	More concurrent systems means simply more satellites
Speed Output	Noisy	Less noise	See data below
Latency	Aggressive filtering	Special filtering with reduced latency	See data below
Location accuracy	Aggressive filtering	Special filtering with reduced latency	See data below

Test setup for the log below:

100Hz device is logged at 100Hz, GPSCAN MK2 50 at 50Hz in the log below
Antennas on the roof of the car
Both devices tested at the same time to get comparable results
No filtering was used

Supported systems and satellites

Above is one test where GPSCAN 100Hz was tested against GPSCAN MK2 50Hz. Note the Yellow box which shows the number of satellites.

Satellites	GPSCAN 100Hz	GPSCAN MK2 50Hz
Average	8	27
Minimum	7	21

As you can see, GPSCAN MK2 is a clear winner. More satellites -> Better overall performance.

Noise in GPS Speed output

Note the Yellow circle in the picture above and shows the noise in the speed output of the devices. This same problem is visible in several locations at 49, 52 mins. As you can see, output is much noisier than GPSCAN MK2 50Hz. Let's zoom into the yellow circle in detail and see the difference:

	GPSCAN 100Hz	GPSCAN MK2 50Hz	Vehicle Wheel Speed
Minimum	81.6	97.4	97.14
DIFFERENCE TO WHEEL SPEED	-15.54kmh	+0.26kmh

Note the drop in the GPSCAN 100Hz speed compared to wheel speed while GPSCAN MK2 50Hz doesn't drop.

Below is another example of the noise, note the noise in red signal (GPSCAN 100Hz) vs Yellow signal (GPSCAN MK2 50Hz).

This quality of signal wouldn't be useable for example as traction control speed, TC would kick in all the time when it shouldn't.

Speed output latency

To see the latency difference, below is a 1G braking event with several speeds including the wheel speed from the ABS system.

As you can see, it is difficult to see the difference, time division is 200ms. 50Hz is very close to 100Hz and wheel speed.

Location Accuracy

This is closely related to the first point, more satellites->better.

GPSCAN MK2 50Hz on the left, GPSCAN 100Hz on the right side. 100Hz track is very poor together due to aggressive filtering, low number of satellites and fast output rate. There is just not enough accumulated data to calculate a good solution.

These are the reasons why 100Hz has been replaced by the 50Hz device and is a better performing device considering all factors.

All 100Hz devices suffer the same problems, there is just not enough accumulated data and filtering is aggressive.