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JavaME tool for static navigation on bluetooth devices
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guest



Joined: 08 Oct 2006
Posts: 5035

PostPosted: Fri May 28, 2010 4:12 pm    Post subject: Re: JavaME tool for static navigation on bluetooth devices Reply with quote

Hello Guido,

I would like to test nosm on my device but there is one issue I did not understand. As far as I have understood "googling aroud", the setting of the boudrate is critical when changing back to NMEA mode. It seems that different gps receivers habe different settings. I guess, that for my device (B-Speech, GPS 20C) the baud rate should be 57.600. Interpretation of your source code seems to use 38.400?
My question is: Does nosm affect this issue (changing baud rate)?
If yes, is it possible to change that parameter?
(Unfortunately I do not have access to a device running SIRFdemo)
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Guido



Joined: 16 Oct 2008
Posts: 16

PostPosted: Tue Jun 01, 2010 12:30 pm    Post subject: Re: JavaME tool for static navigation on bluetooth devices Reply with quote

guest wrote:
Interpretation of your source code seems to use 38.400?

The values in the program are copied directly from a logged SirfDemo session and I did not really try to interpret them. But from the documentation about NMEA and Sirf, it should use 38400 bps for Sirf and 9600 for NMEA.
guest wrote:
My question is: Does nosm affect this issue (changing baud rate)?

I don't really understand that question. The protocols demand setting the bit rate whenever one switches between modes, so nosn has to set and thereby change them.
guest wrote:
If yes, is it possible to change that parameter?

Yes. It should be easier with SirfME, since you would not have to recompile the commands. The biggest difficulty would be the checksums that are part of the commands. Without SirfDemo, you would have to calculate those by hand.
I have some difficulties supporting this tool, since I cannot get it to run on my phone anymore. After some updates to the development environment, my phone rejects the .jar file.
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guest



Joined: 08 Oct 2006
Posts: 5035

PostPosted: Wed Jun 23, 2010 5:53 pm    Post subject: Re: JavaME tool for static navigation on bluetooth devices Reply with quote

[quote="Guido"]
...
[quote="guest"]If yes, is it possible to change that parameter?[/quote]
Yes. It should be easier with SirfME, since you would not have to recompile the commands. The biggest difficulty would be the checksums that are part of the commands. Without SirfDemo, you would have to calculate those by hand.
...
[/quote]

Based on your reply, I decided to get access to a PC with bluetooth capabilities. With that PC I logged the appropriate commands from SirfDemo for my GPS-Mouse with baud rate 57.600. Then I inserted that commands in the configuration file of SirfMe, installed the modified version of SirfMe on my phone (Samsung S5230) and it worked perfectly :D :D

As it could be of interest for the public, here the commands I used to switch to sirf protocol and back to nmea @ 57.600 baud rate (notice: activation of RMC and GGA only, as this setting is perfect for my combination of devices and TrekBuddy!) :

sendString "$PSRF100,0,57600,8,1,0*37\r\n"
sendHex "A0A2001881020101000100010001010100010001000100010001E1000170B0B3"

Many thanks to Guido for sharing this very helpful and great peace of SW with us !!!
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mireazma



Joined: 31 Jul 2010
Posts: 4

PostPosted: Sat Jul 31, 2010 3:37 pm    Post subject: Reply with quote

Sorry for joining the topic in the way I'm doing it but I'd like to know more about this tool. I've read the topic thoroughly but as I'm total new to GPS I miss a few things. I want to buy a GPS receiver to use in car as well as on trekking. Please, spare a couple of minutes and tell me if I got it right:
1. I understand static navigation (SN) is opposed to another concept (continuous tracking). SN offers better accuracy at the cost of increased speed, meaning you don't use it on foot. By this tool of yours you can switch it on and off in the GPS receiver (without turning it off?...). SirfME doesn't support each and any receiver. How can I know if the mouse I'll buy is SirfME compatible? what to look for?
2. Sirf is a mode in which you can switch SN on and off but NMEA is the other mode (normal, universal) in which you can't/there's no SN. So the mouse has to know of both modes, right?
Am I missing anything else?
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Guido



Joined: 16 Oct 2008
Posts: 16

PostPosted: Sat Jul 31, 2010 4:29 pm    Post subject: Reply with quote

mireazma wrote:
1. I understand static navigation (SN) is opposed to another concept (continuous tracking). SN offers better accuracy at the cost of increased speed, meaning you don't use it on foot. By this tool of yours you can switch it on and off in the GPS receiver (without turning it off?...). SirfME doesn't support each and any receiver. How can I know if the mouse I'll buy is SirfME compatible? what to look for?


All GPS receivers are a bit unsharp and the positions they measure tend to jump around. A nav system in a car stopping at a red light may interpret this jumping as actual movements of the car. It would then think that the car is moving in the reverse direction, re-calculate the route and give bogus directions.

One generation of receivers (SiRF-III) tried to solve this problem on the receiver's end by ignoring all (pseudo-) movement below a certain threshold. This works fine in a moving car, but the slow (and real) movement of a walking user is totally ignored. I can slowly walk for miles with my receiver and it will still show the position where I started.

I think that modern receivers do not use static navigation anymore. As long as you avoid SiRF-III, you should be fine. Some SiRF-III receivers may even disable this feature themselves. My old and cheap receiver defaults to static navigation when it is turned on or reset. That's why I needed to switch SN off after every reset, using SiRF-Demo on my PC. SirfME allows me to do this with my mobile phone.

mireazma wrote:
2. Sirf is a mode in which you can switch SN on and off but NMEA is the other mode (normal, universal) in which you can't/there's no SN. So the mouse has to know of both modes, right?
Am I missing anything else?


There are two standard protocols to speak with GPS receivers. NMEA is very basic, but supported by many models. Most navigation software seems to use it. SiRF is a vendor-specific protocol that allows extended features and configuration of this vendor's chipset. Since static navigation is a feature of this vendor, you can configure it only with the SiRF protocol. You have to switch communication from NMEA to SiRF, do your changes and switch back.

When switching modes, you have to set the speed of the communication and you may happen to use one that the GPS receiver supports, but not the Bluetooth module. This renders the device dead until you reset it. That's why doing this may be dangerous. But most devices can be reset to normal by removing the battery or letting it run out of power.

As far as I know, you can buy any device you want. If it happens to use static navigation, then it must be SiRF-III and you can (hopefully) use SirfME to switch it off.

But it'd be much less of a hassle to look for a newer model that does not use static navigation at all. It's not always easy to get this information.
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mireazma



Joined: 31 Jul 2010
Posts: 4

PostPosted: Tue Aug 03, 2010 7:03 am    Post subject: Reply with quote

Thank you very much. It's still nice, to say the least, to have a feature like SN with the condition that you could fine tune the threshold for the speed (which I think you can). This way, with a very low threshold you could make SN yield like normal navigation, leading to eventually needing solely SN.
A feature like switching SN on and off on the fly seems to me more than necessary. It should be embedded in any GPS receiver.
Of course I don't know the resources consumed by the device to switch back and forth between the modes.
Anyway, in Romania there are mostly Sirf III based GPS receivers. So at this time I can't see a more useful tool than yours Smile
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guest



Joined: 08 Oct 2006
Posts: 5035

PostPosted: Wed Feb 01, 2012 5:14 pm    Post subject: Reply with quote

Hi there! My name is Pau, I tried to register but I couldn't so I am connected as a quest... Well, I just wanted to say that I tested SirfMe with a SonyEricsson W880i + Leadtek 9559x and it works fine, without issues! :) So, thank you so much Guido for your job!!
Greetings from Spain!!
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curve 8520



Joined: 06 Sep 2013
Posts: 1

PostPosted: Sat Sep 07, 2013 12:36 pm    Post subject: ERR unable to connect. Reply with quote

This is the error i got on my curve 8520 and BT-338 globalsat.
Am i doing something wrong?
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