SparkFun Forums

[eugen]

Hello,

I would LOVE to see a GPS-Module with the new SIRF III chipset, which enables indoor position fixes. It is such a huge advance compared to the models you have recently in stock. I bought a Lassen IQ from you and it works great as promised, but indoor tracking is what I need...

[NleahciM]

Hello,

I would LOVE to see a GPS-Module with the new SIRF III chipset, which enables indoor position fixes. It is such a huge advance compared to the models you have recently in stock. I bought a Lassen IQ from you and it works great as promised, but indoor tracking is what I need...

So what's different between the SIRF II and SIRF III chipsets? And what would enable indoor gps locks? I mean - does it just have a really powerful built in amplifier or something?

[eugen]

From what I understood, it is not simply amplifying the noise more and more, but it is a different approach in processing the data. It is able to process more so-called correlators (200.000 compared to a few thousand in standard modules) and it handles reflected signals in a different way - so in short the higher processing power with different software allows it to have 20 dB higher sensitivity.
What I don't know how the overall accuracy is affected - but I am not looking for the last meter of accuracy.
Anyway, I've seen it getting an indoor fix in no time, whilst my Trimble IQ waits eternally without result.

[NleahciM]

From what I understood, it is not simply amplifying the noise more and more, but it is a different approach in processing the data. It is able to process more so-called correlators (200.000 compared to a few thousand in standard modules) and it handles reflected signals in a different way - so in short the higher processing power with different software allows it to have 20 dB higher sensitivity.
What I don't know how the overall accuracy is affected - but I am not looking for the last meter of accuracy.
Anyway, I've seen it getting an indoor fix in no time, whilst my Trimble IQ waits eternally without result.

Very interesting. Do you know of any modules currently available? I'd be interested to look at their specs.

[Norman]

I recall reading about a commercial product with this chip inside. I think it was in CQ magazine. Anyway, I was really amazed with their reports of how well it got a satellite lock while inside a house. I'd be interested in products or the chips. Very interesting.

[eugen]

There are not too many modules available yet, and as usual they are considered OEM products. So the average developer has not the remotest chance of obtaining one unless some heroic online shops such as our beloved Spark Fun guys manage to put them into their program.

I know of one available module, it is the Falcom JP10. Google will bring you there. Currently you can order it at an obscure webshop in Germany, but only as SMD BGA part. So no playing with it without custom PCB and reflow oven

[NleahciM]

There are not too many modules available yet, and as usual they are considered OEM products. So the average developer has not the remotest chance of obtaining one unless some heroic online shops such as our beloved Spark Fun guys manage to put them into their program.

I know of one available module, it is the Falcom JP10. Google will bring you there. Currently you can order it at an obscure webshop in Germany, but only as SMD BGA part. So no playing with it without custom PCB and reflow oven

Well it looks like they make a modle JP10-S-C-1 with a "50pin board-to-board, RF connector"

I can't possibly imagine what they need 50 pins for though...

And I also can't seem to find pricing, which is annoying.

[NleahciM]

I would highly reccomend that you all at sparkfun contact the people over at usglobalsat. They make a couple sirf III gps boards that are available right now, though they really only want to sell in OEM quantities so most of us will not be able to buy from them. Specifically I think this board: http://www.usglobalsat.com/item.asp?itemid=63 looks awesome.

[eugen]

Michael,

I second that.

Nice module, integrated antenna and backup-battery. The high level of integration leads me to assume that they will want some serious amount of money for it. But anyway, as long as they keep it a secret one does not need to bother.

A few weeks ago I sent an official inquiry with my sample request to them, but they did not even bother to say no. They are not really interested in business I assume. Maybe Sparkfun would have better chances (should they be interested).

[NleahciM]

Michael,

I second that.

Nice module, integrated antenna and backup-battery. The high level of integration leads me to assume that they will want some serious amount of money for it. But anyway, as long as they keep it a secret one does not need to bother.

A few weeks ago I sent an official inquiry with my sample request to them, but they did not even bother to say no. They are not really interested in business I assume. Maybe Sparkfun would have better chances (should they be interested).

Not horrendously expensive - they quoted me a price of $150 shipped for two of them. It's possible they're giving me a discount as I'm purchasing for a university group though.

[sparky]

Wow! GPS continues to improve - and quickly!

I called and talked to nice guy named Larry. Sounds like it may be a possibility for SFE to distribute.

I love our business model! Find companies that have cool stuff but can't handle small individual orders - then stock their toys so we can sell them (and play with them).

Thanks all for the recommendation! Let's hope we can get the new SiRF III's soon.

-Nathan

[wiml]

it is not simply amplifying the noise more and more, but it is a different approach in processing the data. It is able to process more so-called correlators (200.000 compared to a few thousand in standard modules)

I haven't been able to find any solid information on what makes the SIRF III special, but if it correlates a longer sequence of chips, it effectively gets higher signal gain and better noise rejection. It's exactly equivalent to having a narrower receiver bandwidth on a conventional non-spread-spectrum receiver.

and it handles reflected signals in a different way

Maybe handling multipath better? This is another trick you can do with spread-spectrum signals, it's something that CDMA phones have to do to work indoors (rake receivers). Since you're already doing time-based decorrelation you can sort of line up all the differently-delayed multipath signals. This doesn't just make them interfere with each other less, it lets you extract more signal from the bunch since you're using them all at the same time.

[eugen]

The online shop that listens! Well done! There is now a SirF StarIII based module in your range, and I am sure that this thing outperforms the rest with ease.

Meanwhile I managed to obtain one Sirf StarIII sample of another OEM Module Manufacturer and the first tests show a drastic improvement in reception compared to older modules. I managed to get a fix after cold start indoors within 2-3 minutes.

Your product is very neat and complete. Ideal for cool projects. Unfortunately it requires min. 4.5V and so it is not suitable for my project where one LiPo battery is used. Anyway - I am still tempted to try it for another application. Keep it up!

[pittuck]

u could always get a DC-DC converter... might work, not sure on current requirements.

[NleahciM]

Wow! GPS continues to improve - and quickly!

I called and talked to nice guy named Larry. Sounds like it may be a possibility for SFE to distribute.

I love our business model! Find companies that have cool stuff but can't handle small individual orders - then stock their toys so we can sell them (and play with them).

Thanks all for the recommendation! Let's hope we can get the new SiRF III's soon.

-Nathan

Hmmm... I noticed you took my reccomendation and are now carrying their modules. Being that I'm in the market for one - any chance I could get a "finder's discount"?