I have a Philips Navigator GPS Mk 8 ( about 1995 vintage ) in immaculate condition which goes through self tests with flying colours.--But it will not, even after being on for over three hours, pick up any satellite info and give a position.
Does anybody know of anything I can do to help it along?--or is it unable to handle the massive changes in technology since I bought it? It is very well designed and built piece of equipment and I would very much like to give it another go at life.
I have a 1999-2000 model garmin 12 gps and it still works fine.
i do have a 6-7yo top of the range navman gps for a car which all of a sudden refused to acquire gps signal , think the antenna or gps chip has had a crap out?
Does it show a satellite aquisition and position page at all, if so does it register any sats or strength bars?
The older gps units usually take a long time to get a fix, stating the obvious but make sure you when you test you are in an unobstructed open area to the sky otherwise it will struggle.
is it one of the purely satellite based ones from the early 90's?
a store i worked in during the 90's sold models up to roughly 1995 that would not function properly once the changes in the system were made which caused a reduction in tracking accuracy (mid 90's-ish?), followed by the introduction of terrestrial based transmitters to try and improve accuracy again. I suspect all that early generation stuff is unusable now. that really early stuff was supposed to be very precise (within .5 metres or so?)
does anyone know if the current stuff still relies upon land based signals?
... GPS units of yester-year had less receiving channels i.e. usually 2 (modern ones 12 channels ect) but since there are many satellites out there they had to do multiplexing which is, as each channel picks up a satellite, gets its data and position then the receiver jumps to another satellite and gets its data, using the same channel, then the next and so on.
In order for the machine to know where and when to look at the next satellite, it needs to store the position, time ect of each other satellite. Your GPS unit builds up an almanac of data, details of all the other satellites. If the unit looses this almanac it usually goes looking for satellite 1, and waits for the data to arrive, but what happens is that satellite might be on the other side of the world so you wait and wait for no. 1 to come into view.
Even worse, satellite 1 might be turned off so it may never come. Thus your unit sits and waits.
GPS units now-a-days have multiple channels so can receive data very quickly so if satellite X drops out, it doesn't matter since the other channels are going fine.
This almanac of satellite data is usually stored internally and is usually held there by a back up battery. So, for a circa 1995 unit, chances are that the back up battery is gone so the almanac is gone. The machine wants to get the almanac data back before it will go again.
Anyway, just a thought.
Get a new one and be done with it, new ones are way better anyway and life is short, don't waste it waiting for a damn old GPS acquiring signals.
Robbie 
