Sirf Chip

[+EraSeek]

"Able to track more than 20 GPS satellites, the SiRFstarIII architecture employs the equivalent of more than 200,000 correlators and sophisticated navigation algorithms, a significant improvement over today’s architectures that contain a few hundred to a few thousand correlators, setting a new benchmark for fast and deep GPS signal search and track capabilities even in the most challenging environments."

 

So says a SiRF press release. Which brings me to thinking of how these work and how they vary from the old technology. Tracks 20 GPS sats but the unit still says 12 channel. What you used to see was the 12 best available sats show on the screen as 12 channels. Locked in as bars whether they were locked in for use or not, according the the almanac. Now, with these new CX units, you still have a max of 12 sats but they pop in and out on a regular basis. Not locked by the almanac, but what appears to be a what is actually being used basis.

 

Used to be that even if you were not using a WAAS sat for navigation it could still correct the sats without itself showing even a hollow bar. Now it appears the WAAS sat must be solid and used before it can correct the other sats.

 

Does this jive with what others have noticed?

[rbrugman]

I had a GPSMAP 60c and recently upgraded to a 60Csx. I am amazed by the new chip. With my 60c, I couldn't even get a position from inside my house, but with the new chip, I can get 18-foot accuracy sitting inside my house. When using the GPS in dense tree cover it's just amazing.

 

Only downside is that I think it draws more power. I don't get the battery life I used to, even with the compass off. I bought the unit simply for the new chip and it was well worth the upgrade.

[+jotne]

To day it’s not possible to see more than 12 satellites in the sky at the same time, so there are no reasons to try to track more.

 

Later when the European system (Galileo)are up and running in around 2010, it would nice if the GPS tracks more satellites. (Hopefully they will work together)

 

Tracking more satellites also use more cpu and more power and therefore its also a reason for reducing it to 12.

[+EraSeek]

There are occasions when you can see more than 12 GPS sats. Also with the WAAS sats I could see 12 GPS and 4 WAAS sats where I am. 16 sats. I know they sell 14 channel chips today in units. So that just isn't true. Using more power is not such a barrier espescially with todays improved technology.

[+IVxIV]

I had a GPSMAP 60c and recently upgraded to a 60Csx. I am amazed by the new chip. With my 60c, I couldn't even get a position from inside my house, but with the new chip, I can get 18-foot accuracy sitting inside my house. When using the GPS in dense tree cover it's just amazing.

 

Only downside is that I think it draws more power. I don't get the battery life I used to, even with the compass off. I bought the unit simply for the new chip and it was well worth the upgrade.

 

While I'm sure the Sirf III chip is an appreciated enhancement in GPS technology, I'd caution giving it any more credit than it is due. I bought my Lowrance iFinder Pro back in March 2004 and, it would get an equally reliable position lock while sitting in my livingroom too, about 15 feet in from the nearest window And it's ability to retain signal lock under amazon-like treecover is flat out amazing!

 

Seems nowdays everyone is praising Surf technology for bringing GPS out of the dark ages, but personally I don't think it's as revolutionary as some may think.

[+Rotareneg]

http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=36196

 

Those of you who have seen SiRFstarIII reported as 20 or maybe 22 channels may wonder what the benefit is. As noted above, you can only see 12 or 13 satellites at most at any one time. However you can also usually see a WAAS or EGNOS satellite, and you need a channel for that. So theoretically you only need 13 or 14 channels, yet some receivers have 12, some 16 and some more. What is the benefit?

 

In the SiRFstarIII receiver, there really are no channels in the hardware, only a very flexible hardware architecture that can be reconfigured as necessary for the job at hand. So if we are tracking 6 satellites, we only have 6 (plus a couple "equivalent" channels) in use, whereas if we are tracking 12 satellites we have 12 in use. What is really happening is we are allocating some memory for each "channel" and repeatedly processing the same data for each channel's purposes. In addition to tracking satellites, we are constantly searching for any satellites we didn't know were there, we are monitoring the background noise so we can give a true carrier to noise density reading, and we are constantly validating the signals we are tracking to be sure they aren't cross correlations or autocorreclations. When we say we have 20 or 22 channels, what we really mean is that we have the ability to process the data memory for that many times before it is time to go on to the next block of memory. Memory is filled in real time as we collect data from the RF sampling, but is processed after a buffer is full. Once we finish processing the current buffer, if the next buffer is not yet full, we stop processing so that we save power.

[kb9nvh]

Thanks for bringing this back to reality...I had forgotten some lowrance owners were equally thrilled with their reception..I wonder what chipset lowrance uses??????

 

 

I had a GPSMAP 60c and recently upgraded to a 60Csx. I am amazed by the new chip. With my 60c, I couldn't even get a position from inside my house, but with the new chip, I can get 18-foot accuracy sitting inside my house. When using the GPS in dense tree cover it's just amazing.

 

Only downside is that I think it draws more power. I don't get the battery life I used to, even with the compass off. I bought the unit simply for the new chip and it was well worth the upgrade.

 

While I'm sure the Sirf III chip is an appreciated enhancement in GPS technology, I'd caution giving it any more credit than it is due. I bought my Lowrance iFinder Pro back in March 2004 and, it would get an equally reliable position lock while sitting in my livingroom too, about 15 feet in from the nearest window And it's ability to retain signal lock under amazon-like treecover is flat out amazing!

 

Seems nowdays everyone is praising Surf technology for bringing GPS out of the dark ages, but personally I don't think it's as revolutionary as some may think.

[+Alan2]

I'm curious if the 60csx can be set to shut off the unit after let's say a minute so that when you need another fix you turn it own. Since it recovers its position so quickly, this might be a way of saving power.

 

I notice that this happens with my Pocket PC with SF GPS with Sirf III. Unit shuts off, but then 5 minutes later, I turn it on and it gives me a fix in a few seconds. Seems like an interesting way to save battery power.

[+budd-rdc]

To day it’s not possible to see more than 12 satellites in the sky at the same time, so there are no reasons to try to track more.

 

Later when the European system (Galileo)are up and running in around 2010, it would nice if the GPS tracks more satellites. (Hopefully they will work together)

 

Tracking more satellites also use more cpu and more power and therefore its also a reason for reducing it to 12.

 

I have a Lowrance unit (iFinder GO) with 16 channels, and it saw 13 satellites + WAAS in the sky at the same time once. I do agree that GPSr's don't need all 12 channels to get the accuracy practical enough for us to use.

 

Lowrance has been using SiRF chips for a while - the older units use the SiRF Star II series while most of their new ones use SiRF Star III (same as the Garmin X series), or so it's alleged. I still have no definitive proof on which chip my iFinder GO uses...

[+Rotareneg]

I'm curious if the 60csx can be set to shut off the unit after let's say a minute so that when you need another fix you turn it own. Since it recovers its position so quickly, this might be a way of saving power.

 

I notice that this happens with my Pocket PC with SF GPS with Sirf III. Unit shuts off, but then 5 minutes later, I turn it on and it gives me a fix in a few seconds. Seems like an interesting way to save battery power.

 

Any GPS should do that. The ephemeris is valid for a couple hours so the GPS doesn't have to wait 30 second to download new ones to get a lock on SVs it had previously seen.

[kb9nvh]

There ya have it!!! Lowrance had SIRF's before Garmin!!!

 

To day it’s not possible to see more than 12 satellites in the sky at the same time, so there are no reasons to try to track more.

 

Later when the European system (Galileo)are up and running in around 2010, it would nice if the GPS tracks more satellites. (Hopefully they will work together)

 

Tracking more satellites also use more cpu and more power and therefore its also a reason for reducing it to 12.

 

I have a Lowrance unit (iFinder GO) with 16 channels, and it saw 13 satellites + WAAS in the sky at the same time once. I do agree that GPSr's don't need all 12 channels to get the accuracy practical enough for us to use.

 

Lowrance has been using SiRF chips for a while - the older units use the SiRF Star II series while most of their new ones use SiRF Star III (same as the Garmin X series), or so it's alleged. I still have no definitive proof on which chip my iFinder GO uses...

[+kyot]

Just how does the number of channels relate to the number of satellites?

GPS is not frequency multiplexed - all the satellites transmit at the same frequencies (2 of them) - so it's not 1 channel per frequency or anything.

So? 1 Channel per time slot - somehow?

[+Alan2]

I'm curious if the 60csx can be set to shut off the unit after let's say a minute so that when you need another fix you turn it own. Since it recovers its position so quickly, this might be a way of saving power.

 

I notice that this happens with my Pocket PC with SF GPS with Sirf III. Unit shuts off, but then 5 minutes later, I turn it on and it gives me a fix in a few seconds. Seems like an interesting way to save battery power.

 

Any GPS should do that. The ephemeris is valid for a couple hours so the GPS doesn't have to wait 30 second to download new ones to get a lock on SVs it had previously seen.

 

My question is whether the 60csx can be set to powerdown automatically if no buttons are pressed for a preset time period.

[8mmag]

 

My question is whether the 60csx can be set to powerdown automatically if no buttons are pressed for a preset time period.

 

There's no setting for that presently.

[+TEAM 360]

 

My question is whether the 60csx can be set to powerdown automatically if no buttons are pressed for a preset time period.

 

There's no setting for that presently.

 

There is on my Magellan Gold...you can set it to power off at different intervals if no buttons are pressed, or power off if it doesn't MOVE after a certain amount of time.

 

As far as the Sirf chip getting reception indoors, I suppose that's great if you are looking for a cache under your couch...gives a whole new meaning to 'couch-caching', eh? LOL

[rbrugman]

I had a GPSMAP 60c and recently upgraded to a 60Csx. I am amazed by the new chip. With my 60c, I couldn't even get a position from inside my house, but with the new chip, I can get 18-foot accuracy sitting inside my house. When using the GPS in dense tree cover it's just amazing.

 

Only downside is that I think it draws more power. I don't get the battery life I used to, even with the compass off. I bought the unit simply for the new chip and it was well worth the upgrade.

 

While I'm sure the Sirf III chip is an appreciated enhancement in GPS technology, I'd caution giving it any more credit than it is due. I bought my Lowrance iFinder Pro back in March 2004 and, it would get an equally reliable position lock while sitting in my livingroom too, about 15 feet in from the nearest window And it's ability to retain signal lock under amazon-like treecover is flat out amazing!

 

Seems nowdays everyone is praising Surf technology for bringing GPS out of the dark ages, but personally I don't think it's as revolutionary as some may think.

 

I never really thought GPS was in the dark ages. I think that anything that can pinpoint your location anywhere on the globe is amazing. I just meant that in my field tests my 60csx did out-preform my 60c using the older chipset. Well it may yield the same results as other GPSr's, I think it's a good unit running good software. I persoanlly have not used a Lowrance GPSr, although I hear they are good. I've always just trusted Garmin for my navigation and comparing the two garmin products I have, the 60csx wins out. If you take into account my Quest which is installed in my truck with the over-priced Garmin roofmount antenna - that actually wins. I see 8-foot accuracy all the time even when it's burried under a foot of snow and ice.

[+Rotareneg]

I'm curious if the 60csx can be set to shut off the unit after let's say a minute so that when you need another fix you turn it own. Since it recovers its position so quickly, this might be a way of saving power.

 

I notice that this happens with my Pocket PC with SF GPS with Sirf III. Unit shuts off, but then 5 minutes later, I turn it on and it gives me a fix in a few seconds. Seems like an interesting way to save battery power.

 

Any GPS should do that. The ephemeris is valid for a couple hours so the GPS doesn't have to wait 30 second to download new ones to get a lock on SVs it had previously seen.

 

My question is whether the 60csx can be set to powerdown automatically if no buttons are pressed for a preset time period.

 

Whoops, sorry, totally misinterpreted your post. I think the battery saver mode turns the receiver off and on to conserve power, not quite as good as powering the whole GPS down, but it should help a bit.

[+budd-rdc]

As far as the Sirf chip getting reception indoors, I suppose that's great if you are looking for a cache under your couch...gives a whole new meaning to 'couch-caching', eh? LOL

Being a skeptic, I tried comparing indoor readings on my Garmin eTrex Summit, Geko 201, Magellan GPS Companion, and Lowrance iFinder GO by going outside, projecting and triangulating. They were within +/- 0.002 minutes, so not bad at all. SiRF chips are not required for indoor lock. (one story building, no concrete or metal overhead, 10' away from any windows)

 

iFinder GO claimed WAAS lock indoors.

[kb9nvh]

Hey, now thats an idea....hide a cache inside a building (that has good reception inside) and see how many finds you get. Like maybe under a metal pavillion at a park or inside the caboose on dispaly in our local park. In the pavillion at verison music center at INDY. My gps V would have given up under those but I'll bet the csx would work (maybe your meridian gold too).

 

Anyway, having an extra sensitive reciever and getting reception inside buildings is not the point. Getting good reception under heavy tree cover is or whenever you dont have a clear view of the sky. Opening up options that you did not have before.

 

 

My question is whether the 60csx can be set to powerdown automatically if no buttons are pressed for a preset time period.

 

There's no setting for that presently.

 

There is on my Magellan Gold...you can set it to power off at different intervals if no buttons are pressed, or power off if it doesn't MOVE after a certain amount of time.

 

As far as the Sirf chip getting reception indoors, I suppose that's great if you are looking for a cache under your couch...gives a whole new meaning to 'couch-caching', eh? LOL

[Rhialto]

To save power there is one solution Garmin can implement easily without effort:

 

http://forums.Groundspeak.com/GC/index.php...193&hl=sirf

[+jotne]

For some reason, all information about SiRFStar III LT are removed from www.sirf.com

At least I am not able to find any information, and I know I have seen it there before.

[Rhialto]

For some reason, all information about SiRFStar III LT are removed from www.sirf.com

At least I am not able to find any information, and I know I have seen it there before.

The press release is still there: http://www.sirf.com/Downloads/Collateral/P...3LTfinalIII.doc

[+jotne]

For some reason, all information about SiRFStar III LT are removed from www.sirf.com

At least I am not able to find any information, and I know I have seen it there before.

The press release is still there: http://www.sirf.com/Downloads/Collateral/P...3LTfinalIII.doc

 

Can you tell me were to go at the www.sirf.com if you did not now about the direct link?

[Rhialto]

For some reason, all information about SiRFStar III LT are removed from www.sirf.com

At least I am not able to find any information, and I know I have seen it there before.

The press release is still there: http://www.sirf.com/Downloads/Collateral/P...3LTfinalIII.doc

 

Can you tell me were to go at the www.sirf.com if you did not now about the direct link?

I've done a search on the website but also it is under News & Events then Press Releases

[+jotne]

Normaly when a company comes out with a new product, they like to display it with big letters on the frontpage. Sirf seems to hide this release. Some strange.

 

Anyone who knows if any GPS uses the LT chipset?

[+Searching_ut]

Hey, now thats an idea....hide a cache inside a building (that has good reception inside) and see how many finds you get. Like maybe under a metal pavillion at a park or inside the caboose on dispaly in our local park. In the pavillion at verison music center at INDY. My gps V would have given up under those but I'll bet the csx would work (maybe your meridian gold too).

 

Anyway, having an extra sensitive reciever and getting reception inside buildings is not the point. Getting good reception under heavy tree cover is or whenever you dont have a clear view of the sky. Opening up options that you did not have before.

 

 

When checking accuracy of Sirf chipped units in situations like "under a metal pavillion", I've found the position accuracy to be quite interesting. Your solution is based on a bounced rather than direct signals, which results in quite variable position indications, depending on how far away the surfaces that are bouning the signal are. I've found the sirf based units can be somewhat of a blessing in flatter terrain, heavy tree cover, but the error you can get in mountainous canyons can be quite remarkable, measured in miles rather than feet on occasion. (To be fair, most of the time virtually all GPS units I've used are remarkably accurate, with significant errors being the exception rather than the rule) Set up your unit for time based track recording, get into a situation like a canyon with steep vertical walls, and leave the unit stationary for a couple hours. You can get some pretty interesting tracks doing this. My old sportraks would jump off course and stay there for awhile when recording tracks while moving, but because of the averaging it was hard to tell what they were doing while stationary. My Garmin units are prone to more fleeting but sometimes more significant position errors. The new chip setup however seems to be capable of getting the farthest off course, especially when it comes to being off position and staying there for awhile. Which is preferable to you probably has a lot to do with the sort of conditions you spend your time in the most.

[Rhialto]

Anyone who knows if any GPS uses the LT chipset?

 

I'm trying to find out if the zumo (the latest from Garmin) will use it. WHat disapointed me in the zumo is the 3 hours only when using battery.

 

Also, if both chip are identical and cost the same, don't the 1st one that is more power hungry should simply be left out once all stock are sold and let the LT one rule?

[kb9nvh]

I've not been in that situation (mountains on one side or skyscrapers even).

 

In general, are the places that would give a SIRF receiver the most problems also places that non SIRF receivers would not receive any signal?

 

I can see the engineers building these super sensitive chips up and getting such great reception and then not realizing that getting that good of reception opens up a whole new can of worms.

 

Hey, now thats an idea....hide a cache inside a building (that has good reception inside) and see how many finds you get. Like maybe under a metal pavillion at a park or inside the caboose on dispaly in our local park. In the pavillion at verison music center at INDY. My gps V would have given up under those but I'll bet the csx would work (maybe your meridian gold too).

 

Anyway, having an extra sensitive reciever and getting reception inside buildings is not the point. Getting good reception under heavy tree cover is or whenever you dont have a clear view of the sky. Opening up options that you did not have before.

 

 

When checking accuracy of Sirf chipped units in situations like "under a metal pavillion", I've found the position accuracy to be quite interesting. Your solution is based on a bounced rather than direct signals, which results in quite variable position indications, depending on how far away the surfaces that are bouning the signal are. I've found the sirf based units can be somewhat of a blessing in flatter terrain, heavy tree cover, but the error you can get in mountainous canyons can be quite remarkable, measured in miles rather than feet on occasion. (To be fair, most of the time virtually all GPS units I've used are remarkably accurate, with significant errors being the exception rather than the rule) Set up your unit for time based track recording, get into a situation like a canyon with steep vertical walls, and leave the unit stationary for a couple hours. You can get some pretty interesting tracks doing this. My old sportraks would jump off course and stay there for awhile when recording tracks while moving, but because of the averaging it was hard to tell what they were doing while stationary. My Garmin units are prone to more fleeting but sometimes more significant position errors. The new chip setup however seems to be capable of getting the farthest off course, especially when it comes to being off position and staying there for awhile. Which is preferable to you probably has a lot to do with the sort of conditions you spend your time in the most.

Edited July 25, 2006 by kb9nvh

[+TheBeast]

I've heard a lot of good things about this chip, is there any way to find a list of all the devices tha use it?

[+jotne]

I've heard a lot of good things about this chip, is there any way to find a list of all the devices tha use it?

 

From Garmin

All GPS released after the "x" modell, exept the Legend x and Vista x

[robertlipe]

I've heard a lot of good things about this chip, is there any way to find a list of all the devices tha use it?

 

From Garmin

All GPS released after the "x" modell, exept the Legend x and Vista x

...and venture cx and streetpilot2820.

 

(Their product line is large and confusing.)

[+jotne]

[(Their product line is large and confusing.)

 

Totally agree in that. As a new GPS buyer you would see so many models with only small differences.

[robertlipe]

[(Their product line is large and confusing.)

Totally agree in that. As a new GPS buyer you would see so many models with only small differences.

I'm not exactly new and I still see many models with only small differences - that accumulate to be a real effort to keep with it all!

[+Alan2]

I've not been in that situation (mountains on one side or skyscrapers even).

 

In general, are the places that would give a SIRF receiver the most problems also places that non SIRF receivers would not receive any signal?

 

I can see the engineers building these super sensitive chips up and getting such great reception and then not realizing that getting that good of reception opens up a whole new can of worms.

 

I've found driving arouind in the canyons of Manhattan with my Sirf III gives me reception that is impossible to lock sats on with my old Vista. I believe that the SIrff III is not only more sensitive, but that it has a whole set of algorithms that message that data to make sense out of erratic or weak signals. Why not? All new developments get better the longer they are out. I assume that in the next year or two or sooner, we'll see another leapfrog in accuracy and reception in consumer cost GPS's.

[Rhialto]

I've heard a lot of good things about this chip, is there any way to find a list of all the devices tha use it?

 

From Garmin

All GPS released after the "x" modell, exept the Legend x and Vista x

hmm.. maybe he was talking about the LT flavor of the SiRF III chip.

[+TheBeast]

I've heard a lot of good things about this chip, is there any way to find a list of all the devices tha use it?

 

From Garmin

All GPS released after the "x" modell, exept the Legend x and Vista x

hmm.. maybe he was talking about the LT flavor of the SiRF III chip.

I was actaully looking for a PDA or Smartphone that has this chip in it. Not sure what the LT flavor is.

[Rhialto]

hmm.. maybe he was talking about the LT flavor of the SiRF III chip.

I was actaully looking for a PDA or Smartphone that has this chip in it. Not sure what the LT flavor is.

LT is same chip use 50% power less. There was a few message about it just before yours so that's why I thought you were talking about the LT.

[+TheBeast]

LT is same chip use 50% power less. There was a few message about it just before yours so that's why I thought you were talking about the LT.

Ah! That sounds like it would be the one in a PDA or phone then, being that it's less power hungry!

[+Searching_ut]

I've not been in that situation (mountains on one side or skyscrapers even).

 

In general, are the places that would give a SIRF receiver the most problems also places that non SIRF receivers would not receive any signal?

 

I can see the engineers building these super sensitive chips up and getting such great reception and then not realizing that getting that good of reception opens up a whole new can of worms.

 

 

I would say your assumption regarding a solution where a different unit might not get reception pretty much sums up what I've observed. The question comes down to which is preferable, no solution, or one that can be off by a considerable distance. A few years back now, I did a few comparisons with the at the time most sensitive unit (Sportrak), compared to a etrex legend. Searching for a little over a hundred caches, and comparing hiking tracks side by side for a couple hundred miles I actually decided I prefered the Legend over the sportrak which I had purchased hoping to get better reception than the Legend had been giving me.

 

My current preference is that the Sirf units are great for vehicle navigation, where you're traveling at higher speeds, the software has lock to road and other features that help out in the overall position solution, and having accurate track data isn't critical. For hiking etc. I prefer the older units performance being as how I've found I'm more comfortable having to work to get reception than I am with the possibility that the data I have is quite problematic. For slow speed non road navigation/track logging the unit I use the most is my Forerunner 305. I've found I would much prefer it to have the older receiver section like my 201 but maintain the antenna placement of the new design. The 305 tends to periodically (Every 150 miles or so depending on terrain) log a track that wanders all over the place. It also tends to get fairly confused on mountain trails when compared to my 201.

[kb9nvh]

Well, if I was the guy designing it..I would go for the most sensitive, "signal pullin out of the noise" receiver I could build. Its the software guys that have to interpret that data to give the most palettable result.

 

I just think the software guys need to do more work now to handle multipath better. This sort of thing is being done with digital TV signals now with the latest generation digital receivers and how they handle multipath....I think the TV software guys need to talk to the GPS software guys.

 

 

I've not been in that situation (mountains on one side or skyscrapers even).

 

In general, are the places that would give a SIRF receiver the most problems also places that non SIRF receivers would not receive any signal?

 

I can see the engineers building these super sensitive chips up and getting such great reception and then not realizing that getting that good of reception opens up a whole new can of worms.

 

 

I would say your assumption regarding a solution where a different unit might not get reception pretty much sums up what I've observed. The question comes down to which is preferable, no solution, or one that can be off by a considerable distance. A few years back now, I did a few comparisons with the at the time most sensitive unit (Sportrak), compared to a etrex legend. Searching for a little over a hundred caches, and comparing hiking tracks side by side for a couple hundred miles I actually decided I prefered the Legend over the sportrak which I had purchased hoping to get better reception than the Legend had been giving me.

 

My current preference is that the Sirf units are great for vehicle navigation, where you're traveling at higher speeds, the software has lock to road and other features that help out in the overall position solution, and having accurate track data isn't critical. For hiking etc. I prefer the older units performance being as how I've found I'm more comfortable having to work to get reception than I am with the possibility that the data I have is quite problematic. For slow speed non road navigation/track logging the unit I use the most is my Forerunner 305. I've found I would much prefer it to have the older receiver section like my 201 but maintain the antenna placement of the new design. The 305 tends to periodically (Every 150 miles or so depending on terrain) log a track that wanders all over the place. It also tends to get fairly confused on mountain trails when compared to my 201.

Edited July 27, 2006 by kb9nvh