question

grunkern avatar image

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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6 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:


1579193588430.png (9.7 KiB)
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grunkern avatar image
grunkern answered ·

@nebulight what GPS model is it ?

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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)

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

1579199154764.png (49.1 KiB)
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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Antenna is not external and does not "have a full clear sight to the sky" so that could well be a factor. Thanks @Rob

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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bluejeans avatar image
bluejeans answered ·

I do a lot of biking (pedal not motor) using a tracking app to log my trips. If I stop for a cold beverage in a building that blocks/reduces the GPS signal, I can add a 1/2 mile per beer, to my trip. All of the bouncing around of the GPS signal while the phone is trying to get a lock, shows speed and a lot of movement, when I'm firmly planted on the bar stool. The GPS track for that period looks like a 1st grade kid's scribble. If I sit at an outside table, it does not do that. It shows zero speed and motion. Your antenna needs a better location, for a better sky view

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kevgermany avatar image
kevgermany answered ·

Old thread, but.

My android head unit in the camper has GPS, this always shows a very low speed when stationary. Easy solar in the camper has separate GPS antenna, but shows the same behaviour. I've learnt to ignore it. I guess higher end units have code to ignore these minor values.

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