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gpspassion
93389 Posts |
 Posted - 06 avr. 2005 : 23:22:12
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Right, I was walking slowly, my point is that in these simultaneous recordings SiRFIII benefits from SN being disabled, not XT2 that produces pretty poor results regardless of SN.
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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Carl@SiRF
USA
158 Posts |
Posted - 06 avr. 2005 : 23:36:29
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Xtrac 2.1 software was recently released, and specifically addresses the dynamics issues. I believe testing has shown a significant improvement.
Carl - SiRF Customer Support |
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tthomas
3 Posts |
Posted - 08 avr. 2005 : 21:20:51
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I received my new SIRF III Global Sat GPS.
I’m running SIRF demo 3.61
Excuse my ignorance but I was under the understanding that this was a 20 channel GPS.
SIRF demo 3.61 appears to track a max satellite count of 12 not 20. Am I talking apples and oranges?
If so can someone explain the difference between a channel and a sat.
Thanks
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Carl@SiRF
USA
158 Posts |
Posted - 08 avr. 2005 : 21:55:11
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Thomas,
SiRFstarIII does have the ability to track up to 22 satellites at once. However, with the current constellation there will be more than 12 satellites visible much less than 0.01 % of the time, so the current implementation of the receiver's software only supports up to 12 satellites at once.
You asked an interesting question about the difference between a satellite and a channel. A channel typically represents a subdivision of the hardware dedicated to tracking a satellite, but that definition goes away in SiRFstarIII. In reality, SiRFstarIII has no channels. Rather it has a tracking engine that tracks whatever it is told to track at any given instant. Most receivers track in real time, meaning as the stream of 1s and 0s come in from the RF section, the hardware assigned to track a satellite compares that incoming stream with another stream created inside the receiver and adjusted to match what that satellite should be sending. When the streams match sufficiently, we have a track. SiRFstarIII operates in faster than real time, much faster in fact. But of course that means it must work in the past. It captures a snapshot of the streams of 1s and 0s in a buffer. When the buffer is full the receiving hardware switches to another buffer to collect the next samples while the tracking hardware starts processing the filled buffer. That tracking hardware repeatedly processes the buffer for each satellite it is tracking -- if it is tracking 8 satellites it processes the buffer 8 times, once for each satellite. The tracking hardware is fast enough that it could process the buffer up to 22 times before the other buffer was full and the receiving hardware would need to switch and start filling this buffer again.
Since there are only enough satellites visible at one time to justify 12 "channels" (areas in memory to collect processing results, really), and since currently defined SiRF messages only support 12 satellites, SiRF chose at this time to only implement 12 parallel tracks. When circumstances justify it, we will expand things. Note also, that as processes improve so that we could speed up the chip, that 22 satellite limit will also go up.
Carl - SiRF Customer Support |
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Madman_K
4 Posts |
Posted - 16 avr. 2005 : 11:08:40
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I got a BT338.
I was looking with SirfDemo at the SN.
It was allready disabled (factory setting)
SW-version GSW3.0.2-... |
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telocat
45 Posts |
Posted - 19 avr. 2005 : 21:21:59
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I couldn't get SIRFdemo working correctly with my Xtrac v1 GPS (Fortuna Pocket Xtrack). Seemed to connect OK, but all I got were error messages.
Can this tutorial in any way be applied to Xtrac v1? |
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Carl@SiRF
USA
158 Posts |
Posted - 19 avr. 2005 : 23:12:45
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If the error messages were of the form: Comm: CE_FRAME or Comm: CE_BREAK then you likely have a baud rate mismatch between SiRFDemo and your receiver. You have two choices: manually try each baud rate available (common ones used are 4800, 38400 and 57600, but others are extant), or go to the Action menu and select "Synchronize Protocol and Baud Rate" -- that latter choice will force the receiver to talk SiRF binary at 38400 or 57600, depending on the version of SiRFDemo you have.
Carl - SiRF Customer Support |
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telocat
45 Posts |
Posted - 20 avr. 2005 : 17:12:19
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Carl, Thanks for your response.
Here are some more details:
* I'm using SiRFDemo 3.6.1
* My GPS is a CF Fortuna Pocket XTrack (Xtrac v1)
* I'm using a PCMCIA card to connect my GPS to my laptop
*** I'm able to perform step 2.3 in the tutorial: Launch SiRFDemo using COM 4, 4800 baud. After I connect I see lots of data scrolling in the Debug view. All the data mostly starts with $GPG.... or $GPV...., I haven't figured out how too cut and past from SiRFDemo to show more details.
*** Now when I perform step 2.4, switch to SiRF Protocol, the Debug view stops scrolling and I see many 'Comm: CE_BREAK' and some 'Comm: CE_OVERRUN' messages and you suspected I was seeing.
At this point it seems that no matter what baud rate I choose for my initial connection (I tried them all, only 4800 would connect), SiRFDemo always switches to 38400 baud (seen in the title status) when I switch to SiRF Protocol.
*** I tried "Synchronize Protocol and Baud Rate" with no success.
*** Do I have to have a location fix for this to work? I'm trying out the software indoors where I don't believe I'm getting a fix. I though I wouldn't need a fix because I just want to shut off the static navigation setting.
*** One last thing I noticed is that the Target SW version is UNKOWN as indicated in the SiRFDemo title bar status no matter what setting I choose. I tried to 'autodetect' Target S/W or set it to SiRFXTrac, also without success.
Has anyone else been successful turning off Static Navigation on their CF Fortuna PocketXTrack? Maybe there is a trick to this or perhaps this particular GPS does not have that ability.
Thanks for any additional help. |
Edited by - telocat on 20 avr. 2005 17:14:32 |
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gpspassion
93389 Posts |
Posted - 20 avr. 2005 : 18:03:52
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You want to switch to NMEA/38,400 before connecting from SiRFdemo as it seems your Fortuna doesn't like a simultaneous Protocol/Bitrate switch. SiRFdemo won't let you do that though I believe, but uCenter by uBlox would or CeMonitor that runs on a PocketPC.
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Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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Carl@SiRF
USA
158 Posts |
Posted - 20 avr. 2005 : 18:20:00
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Actually the Fortuna build is somewhat unusual in that it has NMEA protocol on port A and SiRF binary on port B. For that reason you cannot change from NMEA to binary on A since the receiver won't allow the same protocol on both ports simultaneously. And there is no NMEA command that changes the protocol on any port other than the one currently using NMEA. Unfortunately, you therefore cannot change from NMEA to binary with this receiver unless you find a way to reach that second port inside the package (and buffer it -- it only has CMOS drive levels!).
Carl - SiRF Customer Support |
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manolis1976
37 Posts |
Posted - 20 avr. 2005 : 19:25:44
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| i do not understand chapter 5 back to NMEA it means that before i close the program i have to go to actions and back to NMEA? |
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manolis1976
37 Posts |
Posted - 20 avr. 2005 : 19:34:37
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| and press the send buton? |
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Leif
Sweden
141 Posts |
Posted - 20 avr. 2005 : 19:37:41
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My Yakumo delta 300 GPS with firmware 2.4.12.09-XMitac-C4PROD2.0 0000003729 actually has static navigation enabled as default!
After finding a program 'com2com' that relays data between com ports and building a serial cable I could connect COM1: on the PPC with SiRFDemo on my PC to check settings and turn off static navigation. It makes a noticable difference when walking.
Soldering a dense PPC connector is not easy for anyone and 'com2com' only supports 4800 baud making communication difficult, at least with deveopment data on, so a proper SiRFdemoPPC is really needed for most Mitac Mio 168, Yakumo delta 300 GPS, Navman Pin, Medion, etc. owners interested in geo caching or hiking.
My Swedish SiRF rep. has not responded to my request after more than a week.
BR
Leif
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gpspassion
93389 Posts |
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Carl@SiRF
USA
158 Posts |
Posted - 20 avr. 2005 : 20:10:47
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For Manolis1976: you have your choice -- when you change a receiver from NMEA to binary, as long as the battery-backed RAM remains valid the receiver will return to binary when you next turn it on. If that is ok, you don't have to do anything. But if your mapping application or whatever uses NMEA, you probably want to switch back.
One note: the tutorial suggests that you can return to NMEA by doing a factory restart. We do not recommend that. In addition to returning things to their factory settings it also does two other things: erases the clock drift value from memory and erases any stored almanacs. Losing clock drift means that a cold start could take several minutes (depending on how far from "nominal" the GPS crystal is -- the farther it is off, the longer the cold start). Losing stored almanac means that the receiver will have to use the almanac programmed in at the factory, which could be a few months older than the receiver itself. If you have a receiver that saves almanac to flash (standard software receivers, this is not done in Xtrac), you will erase the flash almanac with a factory restart.
Carl - SiRF Customer Support |
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SiRFdemo tutorial (static navigation)
