Laidback

I like the sound of the u-blox 5 module, 1 second acquisition is amazing!

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Laidback

Laidback Carputer

bes51659

Agree!

But then I need a gyro. What do you think of this one?

Epson

Laidback

Both DR kits you linked to have a giro included.

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newb77

This is what I use. No DR but it works great. It doesn't show it in the pictures (or talk about it at all in that particular auction), but it does have a tiny gold MMCX connector on the side of it. I have it mounted in my center console and connected to a 30db gain external antenna. When I travel, I can easily disconnect the antenna, pull the SUG-226 off the hub in my center-console, and then use it with my laptop. I love that thing... super tiny/prtoable, super fast Sirf3 acquisition, and a great internal antenna + external antenna connector.

This also looks interesting.

bes51659

Thanks for links newb77!

External antenna is requirement so the one you use is not an option for me.

Second one would defenitely been what I would have gone for 3 days ago, but now I've really got interested in the consept of dead reconing.

Laidback: Both kits have got gyro's, but the AEK-4R contains rev 4 of the u-blox and is $500 and the second (Lassen DR+GPS) I cannot source.

So I will probably buy the Epson gyro and the rev 5 u-blox unless any of you see any incompatibility.

I will design hw around it and publish (sell maybe) if successful.

Help appreciated.

Laidback

You're going to design the hw to do the DR??

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Laidback Carputer

bes51659

Yes, whatever interface that is needed. Hopfully it does not mean AD converters and such.

From what I understand the DR algoritms and such are integrated in the receiver and all I have to do is to provide gyro signal in accurate format. Similar to your system that only needed an RS232 adapter (correct?)

But I am new to this and have not looked into specs in detail so please tell me if you see any hurdles.

Laidback

Yes, they're integrated into a DR module but I didn't see any u-blox 5 modules with DR. You can't just tack a gyro on to any GPS module. They don't even seem to sell the u-blox 4 DR receiver board seperately, just in the evaluation kit.

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bes51659

Learnings something new every day :-)

So you've bought the $500 kit including DR module? What about the Murata gyro in your thread? Is that the part included in the kit? Getting confused on a higher level...

One way forward would be to get a EVK-5H-0 kit and build a small cpu system that takes the NMEA info from it and together with a gyro signal, tacho and direction and a clever algoritm generates standard NMEA traffic when there is no signal.

If there was such a thing as a USB gyro that algoritm could even run on the carputer.

Maybe its that USB device I should build? Algoritms available? Thread at franson

Laidback

Yes, the 500€ kit has the gyro within.


No, I didn't buy a kit. They used to supply the older DR module on it's own but I got mine second hand anyway.

Algorithms? Look for Kalman Filter algorithm, That's what u-blox use.

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bes51659

I see... I guess the Kalman filter adjusts for signal strength from gyro and tacho gain etc. so that calibration is unnessessary. Below a picture that says nothing to me, but a picture always increase interest :-)



I have googled "dead reckoning" and "kalman" and read wikipedia and realize that there is a lot of development spent in these algoritms and that it is not given away for free.

So I need a DR module and a receiver, but I still think €500 is to much.

So then there is the LEA-4R (USB) and the TIM-4R (UART). Unfortunately they do not contain the newest technology in the receiving department (? confirm?)

These module are €145 and require a gyro with ADC (SPI interface), some kind of dc/dc converter, battery battery-backup and temperature sensor, also SPI (what is temp used for?!). and everything has to go on a pcb with antenna connector, usb connector etc.

No Problem (why is the AEK-4R €350 extra?)

Is there again a mayor part I've forgotten about?

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The €500 kit also contains an Epson gyro, maybe the very same one I saw on ebay that was $60 including p&p from Malaysia!

bes51659

I've just ordered the Lassen DR+GPS at £50 + p&p and the Epson XV-8100CB gyro at $50 + p&p. (notice currency) The gyro is listed in list of compatible devices, so I do not expect any surprices there.

The Lassen DR+GPS kit was too expensive for me at £500. But "Diamond Point" is kind enough to enclude some electronics in their documentation that will save me quite some time. If I had enough money not to care, I would buy the kit.

Thanks for all help so far.

I will post result when done, which will probably be in 2 months or so.

ptk

I am using a Sparkfun's Sirf III based GPS USB evaluation board ET301
http://www.sparkfun.com/commerce/pro...roducts_id=780
in conjunction with a rooftop mounted triplex antennae
http://store.mp3car.com/Roof_top_GPS..._p/com-008.htm

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Laidback

And?

a, It sucks
b, It's fantastic
c, Can't answer now, I'm lost

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ptk

my apologies.

it's working rather well. lock is quite reliable and consistant. bias voltage is applied on the module itself, removing the need to build one's own circuit. lock is near immediate coming out of standby. do remember that the connectors are different, so u need to custom make a inter connecting cable.

kao

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CarPC Ver 3 near completion.