Re: N900 Specifications
 

Does N900 support Java Midlets OTB?since this is just about the only thing which is stopping me from a preorder.

Thanks in advance.

Re: N900 Specifications
 

No. No midlets of any kind.

Re: N900 Specifications
 

Is the accelerometer official? It isn't mentioned in Nokia's N900 technical specifications. So, I'm wondering...

Re: N900 Specifications
 

Re: N900 Specifications
 

This page does not mention an accelerometer, and I can't watch the video on either my laptop or on my N810.

Re: N900 Specifications
 

Ah, well...my intention was to show you the demonstration of the bounce game..which dramatically shows off the accelerometer in action. There are other videos that show the switch from portrait to landscape as you change the orientation of the handset...but they aren't as cool ;)

Short version: yes there is an accelerometer.

Re: N900 Specifications
 

what do you think :D? look at all the videos

Re: N900 Specifications
 

OK, I suppose that the GPS isn't accurate enough and that the cameras aren't used, so that this means that there is an accelerometer. :) I'm still wondering why Nokia doesn't say a word about it in their spec.

I've seen such a video, but isn't it something that could also be done with a gyroscope?

Re: N900 Specifications
 

gyroscope? um, yeah..in theory I suppose if you want to waste money. A solid state gyroscope would be at least as much as the n900 by itself...assuming you could find one small enough. And the gyroscope definitely wouldn't help out in the bounce game with the linear movements that move the ball into the air.

edit: mems single-axis gyroscopes have come down signficantly in price since i last looked....they are now $50-ish. Still doesn't help with linear motion though and they would need to be calibrated occasionally unlike an accelerometer which does not.

Re: N900 Specifications
 

I heard some people on a tech podcast refer to the iPhone's accelerometer as a gyroscope. Plenty other phones have these too, so.......
I'm running out of research time. Can anyone authoritatively explain what exactly is a smartphone accelerometer and how does it work?

Re: N900 Specifications
 

They are pizeoresistive elements that change their resistance values according to how much mechanical stress they are under. Thus, by measuring how much resistance the element has, you can calculate the force it is being exposed to...and by extension the acceleration (F=ma). There are 3 axis in which these elements are aligned, so you can, with some fancy math, calculate the 3-d force vector the device as a whole is experiencing at a given moment. With the proper axis alignment and equations, you can "simulate" a gyroscope's ability to measure angle changes in most cases.

Re: N900 Specifications
 

A DigiTimes article from 2008 said that there would be gyroscopes in smartphones in 2009.

Re: N900 Specifications
 

I guess if you were trying to build an inertial guidance system, they would be useful (if you had something against gps, or couldn't use it for some reason). However, the simple task of detecting the orientation of the handset is easily accomplished with the accelerometer (gravity points down...look for the force vector corresponding to 9.8m/s^2 acceleration and compare to baseline axis orientation to get degrees from vertical)..plus the accelerometer does other things as well (in addition to being immune from the need to be reset/calibrated). For just about every use case I can think of, gps + accelerometer + digital compass trumps the need for a gyroscope set for a non-mission-critical, non-military customer. Since those items have other functions that are useful in their own right...I just can't see the justification for adding the cost of a gyroscope set (3 axes would be an additional $150 plus the added challenge of show-horning them in to an already crowded case).

But that's just me...

Re: N900 Specifications
 

By mechanical stress, do you mean that there is moving parts in there (like a ball that rolls up and down when you tilt it), or what else does it do to induce mechanical stress?

Also wondering if information from accelerometer can be used to make a pedometer app.

Do the current cheap $20 pedometers use accelerometers inside or some other technology?

Re: N900 Specifications
 

There are a couple of designs for accelerometers. The one that texaslabrat describes doesn't really have (easily visible) moving structures or elements per se. Basically, the way that design works is that you get a crystal structure that has piezoresistive properties. That is, the crystal changes resistance depending on the amount of mechanical force exerted upon it (think about the sensations your body feels when the car accelerates and imagine that your body could change resistance accordingly :) ). There are also crystals that have piezoelectric properties which, as you can probably guess, generate a voltage when a mechanical force is induced upon it. There's even a method for building accelerometers by determining changes in capacitance in objects.

And to answer your second question, yes, you can build a a pedometer app that uses the accelerometer. Nokia made one for Symbian S60 3rd devices (I used it on my Nokia N95 and it works pretty nicely). I'm not sure but I'd expect the stand-alone pedometers to use both analog as well as accelerometers to detect steps.

Re: N900 Specifications
 

@BadMojoUT : Thanks for your reply! very informative.

Do you mean something like g-force ?

Re: N900 Specifications
 

yep...exactly

Re: N900 Specifications
 

According to Wikipedia, "Relatively inexpensive (less than US$10 per part as of 2009) vibrating structure gyroscopes using MEMS technology are available." That's far from $150.

Re: N900 Specifications
 

Well, I pulled the $150 from the $50 per single-axis MEMS gyroscope I saw priced via a google search. Feel free to show me a source of actual, purchasable gyroscopes of the proper size to fit inside the already crowded case of a phone like the N900 if you like. In any case, as I've outlined...gyroscopes are largely superfluous anyway as the accelerometer can replace them in virtually all use cases you'd want with a phone (with gps and/or digital compass filling in the gaps) plus, as I've also said before, gyroscopes require occasional resetting/calibration and thus are not a "fire and forget" proposition. What is it with you and gyroscopes, anyway? You own stock in a gyroscope manufacturer?

Re: N900 Specifications
 

With a Google Search: US$4 for a single-axis gyro sensor. The size is 5x5x1.5mm. But miniature gyroscopes are very specific, and I suppose that large companies like Nokia would have better sources than a quick search on Google.

This isn't just me. Look at all the articles on the web. From the Digitimes article: To make their mobile devices appeal to more consumers, smartphones launched by Nokia, Samsung Electronics, Motorola, LG Electronics, Sony Ericsson and Apple, are all expected to come with MEMS gyroscopes in 2009, the sources said. And why does the PS3 controller have a gyroscope instead of accelerometer?

LOL!

Re: N900 Specifications
 

Cool..good to know...and as I suspected they are pretty big. You would need 3 of them for 3-axis sensing and every cubic millimeter you devote to a new gadget is a cubic millimeter less battery volume.

Well, just because somebody wrote an article doesn't mean it's Providence or even a good idea...the fact that said gyroscopes DIDN'T come with smartphones as predicted should clue you in to that. As for the PS3...it has a gyroscope because they decided they wanted the ability to very precisely measure all 6 axes (it also has accelerometers) at additional cost. A better comparison is the original wii controller. which had accelerometers only (they were trying to keep costs down) and did an exceptionally good job for all but the most precise motion use cases due to the excellent software they wrote for the motion control. The $30 add-on brought gyroscopes to the table for more angular precision...but it *added* to the capabilities that were already there (and it does, in fact, occassionally get out of whack and requires resetting/recalibration) . The reverse would not be true (you couldn't have made a wii controller with just gyroscopes and added the accelerometers later).

So, now we get back to the phone world. Exactly what is it that you hope that your phone could do with a gyroscope that can not be accomplished with the already included accelerometer setup? Maybe I'm just not creative enough to dream up what it is that I'm missing out by only having lateral force sensing in my phone.

:D

Re: N900 Specifications
 

IIRC A gyro is quicker and more precise than a digital compass. Think about it as... a compass is good for orientation, a gyro is good for recording motion (especially the yaw component). A compass will never be as precise as a gyro to tell you how quickly you are turning (ever see those iPhone augmented reality apps ? You moooove theee deviiice sloooowly or it get's jumpy real quick). At the same time the gyro will not be able to tell you which way is North without constant (re)calibration, so they are not drop-in replacements. AFAIK no game controller has gyro(s) *instead* of accelerometer(s), they have gyros *in addition* to accelerometer(s).

Re: N900 Specifications
 

The dual-axis gyro IDG-2000 will be released in October and is 4x4x0.9mm, so about the same size of the thinnest 3-axis accelerometer (the volume ratio is 1.28). I don't know the OEM price. The IDG-1215 was $20 per unit (but per thousands, the price should be much lower). So, I don't think it would really be expensive.

Smartphones are not just phones. They have cameras. And it has been said that gyros help image stabilization.

Re: N900 Specifications
 

Not "really" expensive in terms of absolute price perhaps..but it's added space and power consumption that doesn't get you much in the way of new capabilities that people care about. Paying "something for nothing" is not a winning strategy...it's a solution looking for a problem on this kind of platform.

Accelerometers are typically used for embedded image stabilization. What else you got? :p

Re: N900 Specifications
 

I've been wishing for gyro too, even before reading about the AR craze. In my case I wanted them for augmenting gps data to give higher sampling rate. Inertial navigation, but reset every second by gps updates. Gyro calibration can be done automatically when accelerometers indicate no movement, with data from accelerometers and digital compass.

How useful is a digital compass anyway? i've had a few watches with digital compasses, and they required calibration to work at all, and even then they were nearly useless

Re: N900 Specifications
 

This is not what other people say, see e.g. http://www.photographyblog.com/news/...camera_phones/.

Re: N900 Specifications
 

I said "typically"...yes there are high-end devices that include gyros as well (or will...did you notice the date on that article). Until you get the sensor and optics to match, there's little reason to go that route solely for the purpose of photography since accelerometers can do a pretty fine job by themselves. On a phone like the N86 with its 8MP camera (obviously being marketed towards the photography crowd) or actual single-purpose digital cameras...maybe it would be worth it. On the N900...probably not so much given it is expensive and crowded enough as-is. In any case, one would be FAR better off overall with a more sensitive accelerometer (far more general-purpose) than just throwing in a gyroscope when space and power are limited. /shrug maybe some engineers think the tradeoff is worth it if the price is right.

The only thing a gyro can truly do is add a marginal improvement in performance over an accelerometer in some cases. It doesn't add anything "new" worth talking about in a phone platform. If you are willing to pay more, have less battery life and/or have an even chunkier phone for that marginal improvement in pointing accuracy or image stabilization...then go for it. However, I'd wager 99% of the consumer market out there (myself included) is quite happy with the performance modern solid-state accelerometers can give when coupled with decent software (wii controller being a fine example..yes it can be and was improved later, but it was incredible as-is too). If they get down to next-to-free in terms of actual dollar cost, space requirements, and power draw..then sure...throw them in. At that point why not? As it is, there's just not enough margin of improvement to make it worth it for the vast majority of the consumer phone market.

So again..what else you got?

Re: N900 Specifications
 

Yep, and you've ironically missed the fact that a gryo can be *replaced* by that combination of accelerometers, gps, and digital compass rather than just being there to calibrate it. Just because the iphone's (or your watches) digital compass sucks doesn't mean they all have to. I'd take a "good" digital compass over a gyro (assuming I already have a decent accelerometer and gps anyway) anyday. Far more useful in day-to-day activities than the incremental improvement in angle-change detection that a gyro brings to the table.

And as someone who has written gps-data processing software, I think your ideas on the inertial guidance system needs some more work ;) You're not going to gain anything from trying to update the INS every second with gps....gps just isn't that accurate (at least civilian systems) while moving. You'd be better off just relying on the INS with that rate of update. The rate at which it becomes beneficial to update with gps is related to the INS drift rate..which would need to be calculated against a known course with well-defined waypoints. So, while you're on the right track..there's more to it that you've given credit for.

Re: N900 Specifications
 

A compass is required for augmented reality. To determine where your device is looking at requires 3 dimensions:

- GPS: your location on the world
- Accelerometer: the angle you're holding the device
- Compass: the direction you're looking at

To see this in action, you could try Google Skymap on Android phones. You hold your phone against the starry sky and see the names of the constellations you're pointing at on screen.

Re: N900 Specifications
 

All true. Of course, with a camera, one might be able to calibrate a device by telling it which directions were north/south/east/west...maybe?

Tim

Re: N900 Specifications
 

i have a question about the windows live messenger application will it be released just like the one in the windows mobiles ? or how will the chat messenger of hotmail ( msn ) be ?? :confused::confused:

Re: N900 Specifications
 

No, not necessarily g-force. Any acceleration will be measure. These devices will work anywhere even deep space with no gravity. They work because certain crystals can generate small electrical current if the crystalline structure inside are stressed (i.e. deformed). That is if you grab a crystal and squeeze it in you fingers it will generate an electrical current.

Now for the way it works in an accelerometer, think back you basic physics. More specify Newton's 1st law. (paraphrased) An object at rest tends to stays at rest...unless acted upon an outside force. The crystal is mounted in an accelerometer normally at rest. Now when the device it's mounted in moves, a certain amount of force is exerted on the crystal. The crystal wants to stay still, but it's mounting points are pressing against the crystal which will deform the structure of the crystal. Just like squeezing the crystal in your fingers.

And the key is that the crystals inside the accelerometer is that they only measure movement along a certain direction (aka vector in science speak). So you mount 2 (or 3) crystals so you can measure the up/down and left/right movements.

Re: N900 Specifications
 

The term "g-force" is a colloquialism that is generally used to describe acceleration forces felt from an observer's frame of reference...not just the "g" (9.81 m/s^2 vector pointed at earth's center) imposed by the earth's gravity.

Also, the accelerometers used in applications like this utilize changes in the resistive or capacitive properties, not the measurement of a current (voltage). The resistance and capcitance changes are steady-state depending on the strain (hence stress, hence force, hence acceleration) similar to old-school strain gauges.

Voltage creation by piezoelectric devices is dependent on *rate of change* and is far less useful in this use case since you not only have to measure instantaneous voltage but have to keep a history to make that measurement useful. Contrast with a pizeoresistive or capacitive element where the instantaneous measurement of the resistance/capacitance corresponds directly to the acceleration at that very moment without need to consider the history of change to make that calculation.

Perhaps a pedantic correction..but it is worth noting IMHO.

Re: N900 Specifications
 

Perhaps, with something like this and workload of image prosessing? :D

Re: N900 Specifications
 

Does the N900 support OTA software updates?

Re: N900 Specifications
 

Yes it does.

Re: N900 Specifications
 

well I guess if Carmack gave up on using ins in his space rocket, i should give up making a faster speedometer :)

Re: N900 Specifications
 

i want to ask about the memory (storage space)...uptil now i have no clue how it is divided...the device has 32GB of space...and 768MB from it is used for swap RAM...right? so, the rest (about 30GB) is free and i can put there anything i want, right? Coz i read somewhere it has actually just 65Mb of space...so, how is it really?

Re: N900 Specifications
 

See my earlier post on the subject.

The 1GB mounted on /opt provides a place for additional application storage, so ignore that 65MB number as it doesn't have anything to do with the final product.

Re: N900 Specifications
 

so in other words...i will have just 1gb of space only for applications and the rest will be for movies, music, pictures, etc. ? not that 1gb would be small, but let's say i install alot of games...the space will be filled easily...i understand correctly, right? can this be somehow changed? and if i format my device, can i choose which part it deletes or will it delete everything?