Although SIRIF, the industry leading GPS sensitivity chip, was introduced about three or four years ago, Garmin, in the last 120 days, may have finally been forced to include it in what they are calling their "High-sensitivity receiver" eTrex series GPS. If it is SIRIF then you can expect acquisition that is 30 times faster than current units and (finally) a strong signal under trees, inside most structures, and in natural and city canyons.
If you are considering a new GPS you may want to wait a few more weeks to see if the new chip is in fact SIRIF.

I am not up on what is going on in the industry so I don't know if Garmin was forced to do anything or not, but the Sirif chips have been in place in their 60CS series for the last several months at least, so you can get them now.

The 60 series is more expensive then the trex series.

For what it's worth, I notice a clear advantage in terms of speed of acquisition, accuracy, and signal strength in cover in my 60csx as compared to my old etrex.

You can get the "High-sensitivity" eTrex now as well. The problem is Garmin will not disclose, at least so far, which chip they are using in the "new" eTrex. I have used the SIRF chip for years in my other GPS units; and you are right, there is really no comparison. I need another handheld backup unit but I will not buy anything except SIRF; so I will wait and see.

^ Which "other GPS units" have you been using with SIRF? Just curious.

I have had a 60CS series since they first came out. Not SIRF, but its performance is already incredible compared to my previous generation GPS. So the improvement will have to be quite something to get me to upgrade *just for that*.

I think I'll wait until Garmin includes support for the Galileo system. Some other manufacturers are already. Garmin has been a bit slow in many areas lately, too slow to rebuy a model just for one improvement that already should have been in their models a few years ago, like SD cards.

Did your old etrex have WAAS enabled or was it capable of WAAS augmentation? Some of the earlier firmware on the earlier etrex's weren't WAAS capable.

It is actually very difficult to measure GPS accuracy, you would really need to connect the GPS to a PC via the serial or USB port and collect the output data i.e the GPS RTCM output messages then have some software measure statistically the Spherical Error Probability SEP (3D) or the Circular Error Probability CEP (2D) over a period of say 24 hrs. As the GPS satellite constellation is constantly moving or arcing across the sky. The geometry of the GPS constellation gives rise to something called Geometric Dilution of Precision GDOP. GDOP will have an effect on the accuracy of the GPS fix computation throughout the day. Good quality GPS receivers will have a CEP of around 20-25 metres without using differential means.

SEP and CEP is a function mainly of the accuracy of or lack of jitter in the Receivers clock Quartz TXCO and the sensitivity of the GPS antenna design (i.e. many survey antennas are designed to specifically reduce Multipath) and having the best low noise high gain front end amplifier for the L1 frequency (1575.42Mhz). Most of the worlds GPSs TXCO Quartz clocks are manufactured by a single company in New Zealand. Higher quality GPS receivers generally have a separate RF ASIC chip (front end RF PLL filter and RF low noise amplifier) for the front end rather than being integrated on to the same Digital Signal Processor Chip and microcontroller.

For the best improvement in accuracy, differential GPS needs to be employed. This can be achieved by turning on WAAS on the GPS or use something like an external 2 channel MBX-3 Automatic differential beacon receiver which picks up a radio broadcast signal from a differential GPS radio beacon. CEP with WAAS enabled should be around 3-5 metres with a good quality GPS receiver. CEPs of less than 2 metres are possible with a differential beacon reciever with the beacon being less than 100Km away. To improve PRN lock in a poor sky view environment i.e. foliage, being in a canyon or in a high rise area of a city, with a hand held commercial GPS then a secondary high gain, low multipath external antenna should be employed as different GPS chipsets i.e. SIRF or Trimble Lassen etc used internally will have very little noticeable effect unless an L1 L2 RTK GPS receiver is being employed (very expensive survey kit)

The SIRF chipset designs are excellent low cost, low power, efficient designs but the GPS chipset has very little to do with accuracy, speed of acquisition or signal strength as other factors inherent in the GPS system together with the other design choices in the overall GPS receiver design as a whole are much more influential in achieving accuracy and speed in a wide variety of environments. i.e. even the choice of battery in the GPS design will have a more of an impact in the overall GPS performance.



A full 12 channel GPS receiver, maybe Doug could have someone design the GR-10 GPS to fit into the Photon Freedom Micro light.

Anyone doing that is simply wasting their time and your money. A functional Galileo system is at least 8-10 years away away, even assuming they sort out the political and financial deadlock they find themselves in currently. Galileo was a political statement from day one and it has turned out to be an economic non-starter like many predicted. While it would be nice to have an alternative system, don't hold your breath. JMHO opinion, of course.

This Aug 2005 News Release reads to me like Garmin is commited to SIRF.

I think you're right. I hadn't kept up on the SNAFU that is currently going on, thought it was still on-track for being up in the next few years.

I am VERY happy with my current Garmin 60CS (no SIRF). It is so incredibly faster and works in so many more tough situations than the previous gen I had. I typically get fabulous results, can show me which side of a single track dirt road I'm walking on, stuff like that. I have no quibbles with the way GPS is allowed to work right now. I guess what troubles certain people is the U.S. military can degrade it or turn it off at their whim.

So what is the SiRF actually doing? I get the impression it uses less power (which is good), and gets its superior sensitivity mostly "mathematically", practically it may not offer much improvement compared to the same unit that was already very sensitive. Of course, everything about how GPS works involves brain-burning math...

cfraser:

I buy most of my GPS hardware and software from SEMSONS.COM. However lots & lots of folks carry SIRF receivers.

FWIW, I asked a couple of heavy-duty outdoor Garmin GPSMAP 60CS users who upgraded to the 60CSx. They said you definitely CAN notice the faster sat acquisition speed with the SiRF-equipped 60CSx. Under all conditions. So, it's not just some manufacturer hype, it's a worthwhile feature to look for in a new purchase.

As for greater ability under covered conditions, that was a little less definite, but they "thought" it seemed better. Neither are deep canyon or rainforest etc. hikers...

I'll tell you for sure - SiRF III is superior and just plain amazing. No doubt about that. I'm using mapless GPS navigation units in tandem with PC and PDA mapping software primarily in the car for the past 7 years. Quite often we're traveling to the same camping/lodging places by the same routes. So I know exactly the dead spots on these routes where my old GPS (simple yellow eTrex) can't catch enough satellites to pinpoint my position. I have them marked on the map. I've found the best place in the car for my old GPS unit, where it's working best (under the sunroof). And almost bought an external amplified repeater antenna for it...

About 18 month ago I've got the SiRF III based GPS unit. And started using it in parallel with the old one. 10 of 12 dead spots just disappeared from my map. And I'm not anymore concerned about the new unit position in the car. It works fine even in the glovebox! Usually it's just sitting in my shirt pocket all the time (it's tiny and Bluetooth connected). Our most visited urban maze is San-Francisco. My old GPS was not reliable at all near the downtown. The new one works just fine!

And that's just simplistic Holux GPSlim-240.

I'm still quite content with a $15 compass and map. My dad just gave me his hand-me-down car GPS unit. I don't have the heart to tell him that it looks very pretty sitting in its box.

I use a dashboard mountable Garmin GPS V and it's plenty for me on the highway. The unit is for driving and one of the options is for the unit to be biased to a road (assume it's on a road) which gives it an additional piece of info. Setting it up as off-road works, but not as well. Usually though I'm using it as an ETA and mileage calculator. I know I'm on I-5, how far 'til my next gas stop and when will I get there. It does those calculations much better (more accurately) than I can and it's continually updating.

My primary GPS for hiking is a non-mapping and very small Garmin Geko 301. I use it for marking my car's parking spot, landmarks on the trail and (more importantly) major landmarks locations off the map. Preflight includes getting the GPS and map on the same page. GPS batteries last a long time when you only use it for the occasional fix and otherwise leave it off.

Neither unit has SiRF technology, not really needed for what I do.

Yep, I have both GPS Map 60 and a 60cx, the former with the old SiRF and the latter with SiRF III. It's much better at picking up signals in poor conditions. The newer unit can be carried in a rucksack or bag and still work; the older one couldn't so I had to wear it around my neck. Even then it was shielded by my body.

I don't think there's much difference in accuracy, though. The new one usually claims around 12-15ft. It's enabled for WAAS/EGNOS but in practice I rarely get a signal from those satellites where I live.

There may be a difference in acquisition speed but it's pretty nominal if both have good signals. The newer model does show satellite IDs almost immediately (which I think means it has recognised their signature and so has the right frequency and phase), but then you have to wait for the ephemeris to download, which can still take a minute or so. It's mostly luck how long it takes, depending on where in the cycle the broadcast is when you switch it on. Time to first lock is longer if the device is moving or if it's not been used for a few months, which may affect naive comparisons.

The extra sensitivity is a huge improvement regardless. As is having upgradable memory (I have a 2 Gig chip with topographic maps for my entire country) and various other changes.

I have to gloat a little. Up until about a year ago I worked for the automotive electronics part of Motorola - they made engine controlers, braking systems, telematics units (one of them is the OnStar unit), and, in relation to the telematics business they made their own GPS chipset. As a sort of internal consultant I did a lot of work with the telematics and GPS guys.

Well, it wasn't until recently that I found out that the GPS guys were sold to a company named ... SiRF. Cool, the chipset that is in the GPSMAP 60CSx that so impressed me is designed/made by people that I used to worked with. Its a small small world.

By the way, last Saturday I pulled out my old Garmin GPS III+ for the first time in a long time and turned it on (I was thinking of letting my son take it to Scout summer camp - but decided not to). While outside in a clear field it took no less than five loooong minutes to get a 3D lock. In the first minute it saw only one satellite straight overhead. Eventually it found four others with decent signal, but it took a long time. That just reaffirmed how amazing the SiRF GPS chipset is. Even when we went out to Glacier National Park and turned it on in a new location, the 60CSx took well under one minute to get a 3D lock. Amazing. AFter that the lock came in under 30 seconds.

Another thumbs up for the Garmin 60Cx here. Recently I upgraded to that model instead of the 60CSx because I have no use for a barometric pressure sensor or an electronic compass.

My previous GPS was a Garmin Legend. Prior to that I had a Garmin Venture. And have used a basic eTrex at work regularly.

With lots of tree cover and canyons in my area my poor Legend used to lose satellite lock quite a bit. Fast forward to the 60Cx... I am VERY impressed! It seems that almost as soon as you turn it on you are getting a good lock.

I have been using it for about four months now and I'll never go back. SIRF rocks!

Do the Garmin 60Cx and 60CSx have the same SiRF chip set?

Yes, the 60Cx and 60CSx have the same chip set - as do the 76Cx and the 76CSx.

[Oops, KenK beat me to it!]

Yes, I believe they are identical except for:

60Cx - color mapping (C), memory chip slot (x), SIRF.
60CSx - color mapping (C), sensor package (S)[elec. compass & baro. pressure], memory chip slot (x), SIRF.

I've read that the 60CSx can be a pain sometimes because you have to calibrate the electronic compass and barometric pressure sensor constantly. Also, I believe there is no way to disable the barometric pressure, so it's constantly running and draining the batteries a little more; in addition you can't see the GPS altitude, only your pressure altitude.

But that's just from some reading, I have not personally used a 60CSx. After four months of the 60Cx I don't have any desire for either of those bells or whistles.

A couple of web sites, www.gpsinformation.net and www.geocaching.com have some great info on GPS units.

Those new "H" series eTrex units with the high-sensitivity receiver chip look pretty sweet. I was wondering how long until Garmin updated them...

I've got the Geko 301 and it has the same baro altimeter and compass. The compass is the big battery drain so never turn it on. The baro altimeter seems to work pretty good though. I thought that the unit compared the baro and GPS altitudes. Need to check that; regardless it seems pretty accurate in elevation.

From experience. The altimeter and compass in the "S" models are virtually worthless. They don't cost much extra it's true, but the compass is a battery sucker. Here's why I don't like them:

The only advantage the S compass has is that it works when you're not moving. Big deal, most people use a GPS when they're moving, and it doesn't take much movement to use the regular "compass". Certainly everybody on this forum will have a magnetic compass anyway, for backup at the least.

The S altimeter. It is very apparent from the Garmin GPS forums that the majority of people have no idea how to use them properly. They seem to miss the point that it's really measuring local barometric pressure. As the weather changes, or as you move location, the barometric pressure can change, and so will your displayed "altitude". I repeat: you need to recalibrate regularly, if the weather or your location changes more than a bit! Most people rarely even calibrate, and if they do, may not have a local pressure to calibrate to (typically people get readings taken at an airport, which is not much use unless you're there).

I suggest reading the Kestrel 4000 manual for a better explanation than what Garmin gives. I think Garmin doesn't really want you to know just how inaccurate that "altimeter" is in most situations for the average person. You're better off with the GPS-determined altitude in most cases, especially if you have SiRF not much excuse not to go by that, you'll have enough sats. It's mindless, and way more accurate for almost everybody. If you have the discipline of a pilot, then maybe the S altimeter is for you.

I got sucked in too. But it will be no S next time. Rant over! Just trying to save you a few $$

You're completely wrong about the digital compass. When you want to see where to go on your GPS map you will usually stop to take a look at you GPS and take a new bearing on a land object (except you're riding some vehicle). The orientation of your GPS map will be lost at once, or you'll have to know exactly from which direction you came to orient it properly. Or to walk at least 10 yards in some straight direction to make a new one (usually much more than 10!). Not convenient in many situations. The backup compass is a backup compass. I doubt you'll be holding them both in your hands when orienting on the trail.

^ I guess I use my GPS differently. I have not turned on my S compass for at least a couple years. But you are right, it's just my opinion that it's a useless battery-sucking gimmick. Many people would say the whole GPS unit is just that... I'm fairly flexible. Also, I suppose many people might like it on the water. I still prefer a "manual" magnetic compass, it is not a backup for me.

GPS should be quite accurate for small, short, changes of position. Most of the error terms vary relatively slowly. 1 yard is plenty in my experience. For me orientation has always been a non-issue.

I do think it helps to set the GPS to "north up" rather than "track up". With "track up" the displayed map keeps rotating with your direction of travel, and that makes it harder to relate to paper maps and the real world and to keep it related. With "north up", if the unit shows you moving left to right you know you are heading west in the real world.

Wouldn't "moving left to right" be heading east? The old Boy Scout saying I learned explained the directions going clockwise from the top: Never Eat Shredded Wheat (North, East, South, West).

Oops, yeah.

Lucky you I rarely have the GPS location precision better than 5 meters (yards) while hiking in the woods with any of my GPSes. Maybe you're confused with the car navigation devices and software? They have a special algorithm which adjusts your position to the road, so its readings looks stable, continuous, and with very small error. IMHO, that's a plain profanation of reliable navigation principles.

Ditto "LUCKY YOU".

In my experience, one (1) yard accuracy is just out of the question.