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Quote:
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Originally posted by PLC
I have a Globalsat 307 and it works great!
But it does not have XTRAC firmware like the Sysonchip so it can only use satellite signals greater than 26db
XTRAC can use signals as low as 16db
There are many places that I cannot get a signal and I would like to see what strength level the signals are at.
Problem is all utilities I have ONLY SHOW satellites in view and then their signal strength IF IT IS ABOVE 26db.
If it is below 26db it does not show anything except that the satellite is in view... I would like to see the signal strength of these satellites to see if they are above 16db
if so, then I can conclude that XTRAC would be better for me.
Anyone know GPS utilities that will do this?
TIA
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I have used the Fortuna XTrack receiver and in the normal mode it is just as sensitive as any other CF GPS. In the XT mode it can use weaker signals, but it is very, very, very slow to do that. Most of the time it was in the 7-10 second range behind where I was. For walking, that's fine, but for driving it was not usable in that mode. The XT mode is really for hiking, uban canyon walking and maybe off-roading that involves slow movement. The delay in signal processing means that it simply is too far behind to be used in a car at almost any speed over 5 mph.
The point of that discussion was that you don't need to see the signal strength to make the decision if XTrack is better for you.
First, why does the Globalsat lose lock? Is it because of the sky being blocked by buildings? Is it because of blocking from being poorly positioned in your car? If the answer is yes, then the Xtrack won't be able to get a fix either. It still needs a reliably clear view of the sky. It just works better in weakened signals like under trees, or when part of the sky is totally blocked by some structures or really severe thunderstorms, etc., or when the satellites directly above you are blocked but the ones on the horizon are visible but weak (under an overhang). If the Globalsat is suddenly losing ALL signals, like under really big overpasses, in tunnels, etc, the Xtrack won't do any better.
Then answer these questions:
When the Globalsat loses lock will I be moving slowly enought that I can tolerate a 10 second delay in calculating location to maintain that lock?
Is that same 10 second delay acceptable all the time? (Bear in mind that to change from normal to XT mode you have to remove the CF from the slot, move the switch and then COLD start the receiver (3-5 minutes, minimum), so it's not something you do "on the fly."
If the answer to either question is "no," then the XT is not for you. If the answer to both is "yes," then by all means the XT will be useful.
In direct answer to your question, I don't know of any software to show the satellite strength below the threshold. I'm not even sure if they actually send a NMEA statement on any satellite below the threshold. If they do, then you could use any of the utilities that capture the raw NMEA statements and use this information to parse out the information. This is the structure of the NMEA statement that sends satellite information:
GSV - Satellites in view
GSV,2,1,08,01,40,083,46,02,17,308,41,12,07,344,39, 14,22,228,45*75
2 Number of sentences for full data
1 sentence 1 of 2
08 Number of satellites in view
01 Satellite PRN number
40 Elevation, degrees
083 Azimuth, degrees
46 Signal strength - higher is better
<repeat for up to 4 satellites per sentence>
There my be up to three GSV sentences in a data packet