question

grunkern avatar image
asked · Jan 16, 2020 4:44:44 PM

USB GPS Module has Speed recorded on Venus OS When Vehicle is Stationary ??

Help please ?

Set-Up is Raspberry Pi 3 with Venus OS publishing to vrm site and there is a USB GPS plugged into the Raspberry Pi 3.

This is in a stationary vehicle. Why do I see a Speed published on the VRM portal ?


Thanks in Advance
Robert

Venus OSRaspberry Pisoftware
venus-speed.png (142.3 KiB)
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4 Answers
nebulight avatar image
nebulight answered ·

Could be an overly sensitive sensor? I also have a Pi and a USB GPS and mine shows zero, but oddly enough it isn't displaying altitude:


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grunkern avatar image
grunkern answered ·

@nebulight what GPS model is it ?

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nebulight avatar image nebulight ·

I have the MR-350PS4 SiRF Star IV. It shows up on the GUI of the GX, but not in VRM:

1579198074945.png (21.6 KiB)
grunkern avatar image grunkern nebulight ·

I think maybe the VRM is getting the Altitude from the Location info when you set Location and not getting that info as GPS data ?
- I set that as the Vehicle is stationary and parked up in same spot for much of the time or it is say a Home Location

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Rob Fijn avatar image
Rob Fijn answered ·

The speed is calculated from the positions. Normally every second, if the position jumps are big, this will give you a speed... even when you are not moving.
It could be that your antenna does not have a full clear sight to the sky. Or maybe interference.

Some model GPS units average the speed over the last 5 seconds..

Try to move the antenna a bit.

Rob


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grunkern avatar image grunkern ·

Antenna is not external and does not "have a full clear sight to the sky" so that could well be a factor. Thanks @Rob

Rob Fijn avatar image Rob Fijn grunkern ·

Hello Grunkern, Yes, likely the HDOP value is high. This is a statistic weight of the quallity of the position calculation. It can only improof by receiving a better signal from all sides of the sky. (what is not always possible).
Best regards,Rob

lklmenterprises avatar image
lklmenterprises answered ·

Out of interest what USB GPS units are we using? I am just setting up an Pi 2 with the Venus setup, all working well, and wanting to add GPS now.

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