Kerry.

Probably going to depend on a few things including the constellation and your own orientation. Holding up a little higher probably clears the effect of the body as an obstruction as sat signals are line of sight and ones body is enough to stop them. That's the idea behind external antenna's as they generally get the recieved signals away from any obstructions. Possibly pick up that extra previously obstructed satellite (or 2 or more) and it might be enough to improve the constellation geometry (PDOP, HDOP etc) considerably and since accuracy is basically directed to DOP, improve your DOP you'll improve your basic accuarcy to a point. Generally for best reception with a handheld try to face the equator as there's no satellite orbits over either of the poles. As for external antenna's they also have a preferred horizontal orientation (try one upside down and see what happens) and any tilting can cause an artifical cut-off horizon. Cheers, Kerry. I never get lost everybody keeps telling me where to go

no flame wars aren't good but reality and impression is rather different to that. I suppose the real question is (which will answer a lot of questions) is do you actually believe 3-4 feet is reality in the first place Cheers, Kerry. I never get lost everybody keeps telling me where to go

no flame wars aren't good but reality and impression is rather different to that. I suppose the real question is (which will answer a lot of questions) is do you actually believe 3-4 feet is reality in the first place Cheers, Kerry. I never get lost everybody keeps telling me where to go

3 or 4 feet was simply coincidence but 20 feet is more like it. Both simply an estimate and more a relative guide only than anything absolute. Cheers, Kerry. I never get lost everybody keeps telling me where to go

3 or 4 feet was simply coincidence but 20 feet is more like it. Both simply an estimate and more a relative guide only than anything absolute. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by SamDeG:They also want to develop it for expressly for the civilian market. (although why that makes a difference I don't know) That's what they call a user pays system. Not all of it will be but certainly the planned subscription services. So many different countries involved but in times of "difficulty" how will these countries divy up the control etc etc. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by SamDeG:They also want to develop it for expressly for the civilian market. (although why that makes a difference I don't know) That's what they call a user pays system. Not all of it will be but certainly the planned subscription services. So many different countries involved but in times of "difficulty" how will these countries divy up the control etc etc. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Pneumatic:However, the WAAS sats are in geosynch orbits, but they're not used for positional information directly. Actually the WAAS GEO's can be/are used as a GPS ranging source from ranging data from the WAAS type 9 message. WAAS is required to maintain WAAS network time within spec to GPS time but there are some ranging problems at times to these 2 GEO's. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Pneumatic:However, the WAAS sats are in geosynch orbits, but they're not used for positional information directly. Actually the WAAS GEO's can be/are used as a GPS ranging source from ranging data from the WAAS type 9 message. WAAS is required to maintain WAAS network time within spec to GPS time but there are some ranging problems at times to these 2 GEO's. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Simply being able to receive a WAAS signal doesn't mean all that much unless one is actually within the ground station network proper. As the old saying goes, only in America, only in America and then with problems especially for applications for which is was never designed or intended. Recreational type handhelds really don't and probably won't have the refinements in the software to make use of the what the system is really all about even if they can adequately recieve a signal from the present inadequate geo satellite configuration. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Simply being able to receive a WAAS signal doesn't mean all that much unless one is actually within the ground station network proper. As the old saying goes, only in America, only in America and then with problems especially for applications for which is was never designed or intended. Recreational type handhelds really don't and probably won't have the refinements in the software to make use of the what the system is really all about even if they can adequately recieve a signal from the present inadequate geo satellite configuration. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Even though Selective Availability hasn't been exactly terminated/switched off (as such) it has been set to zero and effectively doesn't really exist and there's been no indication that SA has ever been re-activated. But Selective Deniability is an unknown and a little different to the original blanket cover of SA but again I doubt if any firm confirmation of that being used is available either. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Even though Selective Availability hasn't been exactly terminated/switched off (as such) it has been set to zero and effectively doesn't really exist and there's been no indication that SA has ever been re-activated. But Selective Deniability is an unknown and a little different to the original blanket cover of SA but again I doubt if any firm confirmation of that being used is available either. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Well to satisfy some peoples curiousty it's fairly simple to show just how immune GPS generally is to weather. With the number of permanent recording stations around the world all one needs is a specific date/time/location of the meanest weather one can offer and process/analysis the data. GPS (or the GPS signals) is actually used in the weather prediction process but the thing is it's a "system" not simply a single signal. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Well to satisfy some peoples curiousty it's fairly simple to show just how immune GPS generally is to weather. With the number of permanent recording stations around the world all one needs is a specific date/time/location of the meanest weather one can offer and process/analysis the data. GPS (or the GPS signals) is actually used in the weather prediction process but the thing is it's a "system" not simply a single signal. Cheers, Kerry. I never get lost everybody keeps telling me where to go

http://www.bcbid.gov.bc.ca/data/itqs/130_1070-25-064.htm Cheers, Kerry. I never get lost everybody keeps telling me where to go

http://www.bcbid.gov.bc.ca/data/itqs/130_1070-25-064.htm Cheers, Kerry. I never get lost everybody keeps telling me where to go

I'd check the software version/date as that sounds similar to some EOW problems but that event was back in August 1999. Is the unit that old? Cheers, Kerry. I never get lost everybody keeps telling me where to go

I'd check the software version/date as that sounds similar to some EOW problems but that event was back in August 1999. Is the unit that old? Cheers, Kerry. I never get lost everybody keeps telling me where to go

Simply markers which aid the marking/finding of the actual permanent mark in the ground. Over here normally placed within 3 to 4 feet of the ground mark and could be a single post or 2 posts (one on either side) or 3 (triange) or 4 in a square around the mark. Usually only about 3 foot high (normally painted to stand out) or so and can be a round steel pipe, star picket or wooden post etc. Basically tells/alerts others to the presence of a ground mark but off course doesn't always stop the marks themselves from being damaged/destroyed. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Simply markers which aid the marking/finding of the actual permanent mark in the ground. Over here normally placed within 3 to 4 feet of the ground mark and could be a single post or 2 posts (one on either side) or 3 (triange) or 4 in a square around the mark. Usually only about 3 foot high (normally painted to stand out) or so and can be a round steel pipe, star picket or wooden post etc. Basically tells/alerts others to the presence of a ground mark but off course doesn't always stop the marks themselves from being damaged/destroyed. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Depends on what you want this interface to do. Those 3 character "sentence ID's" by themselves probably don't do much for you as APA is an old Autopilot sentence, XTE is Cross track error and GSA is GPS DOP and active satellite information. A particular NMEA version will comprise a range of different sentences depending on what the output requirements/devices are. Positional NMEA output will be something like GGA, GLL but NMEA being a broadcast type protocol all sentences selected are simply broadcast to all devices. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Depends on what you want this interface to do. Those 3 character "sentence ID's" by themselves probably don't do much for you as APA is an old Autopilot sentence, XTE is Cross track error and GSA is GPS DOP and active satellite information. A particular NMEA version will comprise a range of different sentences depending on what the output requirements/devices are. Positional NMEA output will be something like GGA, GLL but NMEA being a broadcast type protocol all sentences selected are simply broadcast to all devices. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Atilla the Pun:Why is HDOP greater than VDOP? AtP You might be getting the DOP's mixed up HDOP is the lowest order DOP For any given day the general order from bottom to top goes something like HDOP < VDOP < PDOP < GDOP and TDOP floats between HDOP & VDOP and can be <= HDOP. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Atilla the Pun:Why is HDOP greater than VDOP? AtP You might be getting the DOP's mixed up HDOP is the lowest order DOP For any given day the general order from bottom to top goes something like HDOP < VDOP < PDOP < GDOP and TDOP floats between HDOP & VDOP and can be <= HDOP. Cheers, Kerry. I never get lost everybody keeps telling me where to go