3D Robotics Comment by Chris Anderson on September 11, 2009 at 8:56pm

Wouldn't any AP system powerful enough to need such a high-performance GPS already have its own data logging capability?

Comment by Angus Peart on September 11, 2009 at 9:02pm

For a high performance GPS module you are dragging it down quite a bit by limiting yourself to the NMEA protocol.

Comment by Scott Plunkett on September 11, 2009 at 9:13pm

It very well might - or might not...it just seemed a logical convergence to me - I'm sure if we end up moving forward we could create a couple of versions, all with the same high performance antenna, but with variable GPS chipset solutions (Sirf, Venus, etc.), and with or without the logger - my real point was to try to determine where the pain points are for these modules. I'd even be willing to donate profits to DIY Drones if you guys wanted some of them to sell. Without learning preferences, price points, etc. it is difficult to determine whether or not this is even a viable idea or if quantity runs (over 100 units) would be practical.

3D Robotics Comment by Chris Anderson on September 11, 2009 at 9:31pm

I think the question is really "what problem are you trying to solve"? If you want 10Hz and quick starts, the new Locosys modules are good. If you want high sensitivity and a helical antenna, the 5Hz uBlox that we use is excellent. Both offer binary modes, which are much superior to NMEA.

What is the weakness in these options that you're trying to address?

Comment by Scott Plunkett on September 11, 2009 at 11:41pm

Binary vs. NMEA is another debate - basically all the binary protocols are proprietary to their companies (Sirf, UBlox, etc.) and something about that just bothers me. I get that the Sirf binary mode does have some additional features and benefits - but when you are connecting to other devices like an OSD or are sending telemetry - I guess with some additional work one could come up with a solution that output both on separate channels, It would be interesting to know if the uBlox module outputs the same signal to all ports (USB, I2C, UART) -

Regardless, the part I am considering has a binary mode, but who knows if it is compatible with the other vendors.

To answer the question specifically, I am looking for a 10Hz GPS connected to a Quad-Helix antenna / LNA package...and the data logging capability just looked good to me (saw it on some of the Locosys boards) and I wanted an intuitive way to retrieve that data. The microSD / USB option seemed elegant to me.

Comment by Angus Peart on September 11, 2009 at 11:41pm

Just another point, the passive Sarantel is actually preferred over the active one amongst some uav groups, especially the paparazzi group.

Comment by Scott Plunkett on September 11, 2009 at 11:45pm

So I guess what I am asking is...If you got all of the above features (and the vaunted binary output capabilities), and the whole thing came in at under 120 bucks, would that be worth it? What about at $100?

Comment by Scott Plunkett on September 12, 2009 at 12:16am

From my research, passive vs. active is usually a matter of pairing and power consumption - obviously if you cant spare the extra mW, you go passive - but if you have some power to spare, and do the engineering right for the noise, I think the extra Gain is worth it - especially when paired with a chip set that reacts well to having the amplification on board. The one from this solution does not require an active antenna, but I chose one.

Out of curiosity what were the arguments for / against active antennas?

Comment by Mike on September 12, 2009 at 12:18am

Scott,
under GPS Module Specs you have fix rate of 10Hz but under sensitivity you have the power requirement for 1 fix/s - what would it be at 10Hz?

If I could get an accurate 10Hz GPS for $120 yes I would buy.

I have to say I am somewhat skeptical as if it is easy enough to do why has it taken so long for the major manufacturers to give us reasonably priced GPS modules with >1Hz? Just a thought....

Look forward to the results of the first tests!

Mike

Comment by Krzysztof Bosak on September 12, 2009 at 12:20am

People doing DIY projects are more eager to test 10 components for 60USD than buy once for 300USD.
This way we can test more and gain experience, while matching product to our needs.
Therefore I suggest splitting GPS, antenna and logger part.

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