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GlobalSat BU-353 S4 USB GPS receiver
tcassidy
I realized I also have a MTKII chip GPS, the iBlue GM-2, another USB device. I did a quick comparison and would have to say the BU-353 S4 is superior. This may be result of the GM-2 design though, rather than the chip itself. Still, it shows the BU-353 S4 to be a great unit.

Again, I was not able to use the Cold Start feature!

Terry
Attached Images
s4-gm2-comparison.jpg  
tcassidy
Just in case it is not clear where I am, here is the S4 and S&T (2004?)!

Terry
Attached Images
s4-s-t.jpg  
tcassidy
Quote:
Originally Posted by Ken in Regina
Re Windows loading the driver when you plug in the S4, my notebook threw an error when it tried to do that. That's why I downloaded it from GlobalSat.

...ken...
Funny! Even with the GM-2, although Windows didn't have a driver, it directed me to a site to download what was needed.

Maybe I'll set it up again and try to get some screen captures of the process. As its a Prolific driver, I only need to move it to a new USB port (if I have any left).

Terry
SpadesFlush
My first cold start was about 45 seconds and everything else since then has been 'warm' and about 2~5 seconds.
SpadesFlush
My problems reported earlier with the GPSinfo.exe program seems to be that the version provided on the in-package mini-CD is probably 32-bit only. Installing the version available from the website that Terry provided the link for above, gives me a working GPSinfo.exe file on my 64-bit PC.
tcassidy
I ran the driver test this morning but used a different computer to ensure the driver wasn't already present. I connected the BU-353 S4 to my Fujitsu Win 7 32 slate as it has never had the Prolific driver installed. Still, the identification and driver loading went very smoothly.

I used PicPick to ensure I could quickly get a series of screen captures. Other than that, I only had to click on 'Click here for status' to allow the other screens.

Terry
Attached Images
353_1.jpg   353_2.jpg   353_3.jpg   353_4.jpg   353_5.jpg  

Ken in Regina
I figured out the driver issue. It was a setting on my new computer that was stopping Windows from using Windows Update to search for a driver if there isn't one already on the computer.

Problem solved.

... Sort of. When I plugged in the GM-2, Windows didn't find a driver even when it was allowed to hunt the internet for one so I had to resort to a manual install of the CP210x driver. (I used the one for the i.Trek M7.)

I downloaded GPSInfo from the link you provided above. It's a different version than what's on the miniCD that came with the S4. I like that the information display is now all on one screen.

I was able to connect two GPS receivers to the notebook and run two instances of GPSInfo side by side for direct comparison which I could not do with the other version. Another problem solved.

I pulled out the Transystem GM-2 (MTK chip) for some comparisons with the S4 (SirfStar IV chip). From a strictly performance perspective, there does not seem to be anything to choose between them at my kitchen table. I'll test them in my basement office this afternoon. I'm pretty sure the GM-2 can get some kind of location fix down there. We'll see if the S4 can, too.

The main difference between the GM-2 and the S4 is the usability. And it's a huge difference

GlobalSat made a very wise choice leaving the serial communication set at 4800bps. That's a setting that provides sufficiently quick position updates for navigating anything except maybe a jet fighter and it works immediately with any navigation software.

The GM-2 defaults to 115200bps. That's going to be a problem for some folks. You need to know that the reason things aren't working is probably because of the COM port speed setting. And you need to know what to do about it. And you need to have a way of dealing with it.

Even some programs that will scan for active COM ports will not scan the port speeds up to 115200. GPSGate is one of the smartest for finding your GPS receiver and even it won't find the GM-2. You have to manually set the input COM port speed to 115200 before GPSGate will use it. Then you can use GPSGate to throttle it down to 4800 for programs like Streets & Trips.

So with minimal performance difference between the two receivers, the S4 wins hands down for immediate usability.

In my view, anyway.

...ken...
tcassidy
I agree wholeheartedly Ken. And I recall the original software that came with the GM-2 wouldn't change the bit rate even though it is possible with an older software version.

For my screenshot, I didn't even bother to track down the appropriate software ...just ran GPS Info at 115,200 for that instance.

Terry
MrUmbra
The GM-2 can provide 5 fixes per second. That's probably why the baud rate is 115200.

--- CHAS
tcassidy
I think Ken's point was the GM-2 should ship preset to 4800bps to satisfy the largest number of customers out of the box. IIRC they did with later shipments.

What I didn't like was the software shipped with it did not allow one to change the bit rate while a previous version we had from our iTreks did!

Terry
SpadesFlush
I have had a chance to do some field-testing of my new BU-353S4 now and I thought I would share some of my observations. First, I should make clear that I cannot compare it to an S3 version because I do not have one. So, my personal benchmark would be the GPS receiver that is built into my Viliv S5. Second, I should point out that this is in no way a balanced test; all terraines, all conditions, etc. However, I did use it in a fairly hostile environment: Manhattan. I say "hostile" because the tall buildings we have here are not friends of GPS. When they are not busy blocking out the GPS signal, they are distorting it as the signals bounce off their large, flat, vertical surfaces.

The S4 definitely out-performs the Viliv, however. An easy indicator is how many satellites are being recognized. For instance, parked between two 50-story towers, the Viliv showed 4 where as the 353S4 showed 7, 8, or 9.

The S4 produces a relatively true and straight GPS trail that seems to be pretty accurately positioned. You can even see where I had changed lanes. No, I did NOT cut off that taxi! I was there first. Even on relatively wide streets with low-ish buildings, I would get a sort of saw-tooth effect on the GPS trail with Viliv as the recorded trail was distorted by varying signal qualities.

The start-up seems almost instantaneous. After being on standby and resuming the GPS navigating, I had a red dot before I could get the key in the ignition. This is a major boon.

Also, the location lag seems to be substantially reduced. In other words, the red-dot or arrow in Streets and Trips is much closer to where you actually are rather than where you were 5 or 10 seconds ago. This can be a real help in giving driving directions in unfamiliar territory although I have not actually tested that.

So, in summary I am favorably impressed. I cannot think of any negatives. Get one!
t1d
Quote:
Originally Posted by SpadesFlush
Also, the location lag seems to be substantially reduced. In other words, the red-dot or arrow, is much closer to where you actually are rather than where you were 5 or 10 seconds ago.
SF, I have the S3, with which I am thoroughly pleased. I understand that you do not have my model, so you can not make a comparison between the two as to tracking lag. But, I would appreciate it if someone else could comment on what I should expect pertaining to lag... About the only incentive I would have to upgrade would be a reduction in lag... Thanks...
tcassidy
My understanding is the Viliv internal GPS is based on SirfStar III technology so it is a fairly reasonable comparison. However, as I cannot think what would cause the lag, I can't see how a more sensitive GPS would reduce it.

Terry
Ken in Regina
Given the potential limitations of antenna size and positioning possibilities between an external device like the BU-353 S3 and the internal S3 chip in the Viliv, I would not assume there is any basis whatsoever for comparison. In fact I would fully expect the internal chip in the Viliv to perform much worse in almost any test, versus the BU-353 S3, because of its severe limitations.

That is not a criticism of the internal chip in the Viliv. It is simply an observation of the limitations of any built-in GPS chip, in PCs, tablets and phones.

Regarding the lag issue, a GPS chipset will not deliver the necessary position sentences to update a position until it has determined a position it is confident to be stable. In a limited or impaired reception situation the chip may be doing multiple position fix acquisition and analysis calculations for any single position delivered to the receiving/display application. This could result in varying amounts of apparent "lag" in the position display.

Or the error factors being delivered with a position fix (HDOP, etc.) may be sufficiently bad that the receiving/display application may simply reject many of them and may only update the position display when it receives fix updates within an acceptable range of error.

...ken...
tcassidy
I agree with you on placement issues Ken. The S3 would have a better sky view than the internal GPS of the Viliv depending on placement. However, I find your lag explanation to be based on a few too many assumptions we are not able to prove to state the S4 would reduce it.

Maybe I'll have to try S&T with each to see. But I am somewhat limited to only good reception areas while travelling!

Edit: Marvin, you have both and access to a large metropolitan area. How about a hands on!!

Terry
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