GPS Baud Rates, I-gates, etc.
Gentlemen,
I guess I will have to check your page more diligently! First, the RTG is perfectly happy to accept 4800 or 9600 Baud, but you have to select which one you want to use in configuration. It does not auto-detect the Baud rate. It still needs to me standard NMEA format. If you have a programming cable, it's easy enough to change, or I can reconfigure it for you.
The Internet knows the IP address of an I-Gate, but its actual location can be anywhere, and there is no special reason that the APRS-IS has to know or announce where it is...it can be a Ghost-Gate.
An I-Gate may receive signals directly, or bounced off multiple digipeaters. Irritatingly enough, a Digipeater can also be a ghost, with no position showing, or a bad position, like a string of zeros ( You would not want to live on the place on the planet with all zeros in its lat-long, you could step off he edge and seriously hurt yourself) A Digipeater can also be an I-Gate, without respect to whether there is another I-Gate 300 feet away. This can and will result in the same tracker's packet being sent to the APRS-IS (Internet) from two different I-Gates, not necessarily at the same time, and the packet may still be digipeated again, to weasel itself into some other unsuspecting I-Gate and confuse the poor mapping software at aprs.is, etc.
This is of course, democracy in action. The "system" ( Really a voluntary association of free-agents, often with contradictory goals) generally tolerates this kind of redundancy. Some Digipeaters just decide all on their own to receive packets, and just sit on them for awhile before transmitting. You may have seen a course track that suddenly shows a backtrack in a course that you know did not actually happen.
If you experience errata in mapping ( Call Hessu in Finland, not me!
) You should open aprs.fi, click on your station so that everyone else disappears, and over on the right hand side of the screen, use the button to display "Raw Data". If the right hand of that box is filled with all kinds of dire comments, like "Delayed Or Unsupported Packet" "Out of Sequence" or allegations of illegal time-travel and they have decided to disown you, there may be a problem with your local system. ( There is always a problem with local systems, fret not) Go back to your area of interest, pick a random tracker, and try that test again. If they have a Raw Data page filled with red text, you have one or more cranky digipeaters. ( These are best fixed with a hammer, or a shotgun, or at least reconfiguration.)
Information about range and bearing to stations is inferred by the mapping program (aprs.fi, etc) I would not rely on that piece of info to fly a course home, or call in an artillery strike.
Our TT4-based products, like the MTT4B, calculate range and bearing to a target (Dare I use that word? I dare, I dare!) from the tracker-end, and you can display that on our optional LCD display, but again, we only really know where the target claims to be, not where it really is. Schrodinger's Cat got out.
73,
Allen AF6OF
VHS/BYONICS