Hi Carl and everyone, I have used the Talking Compass (which I found to be too general in terms of heading information) and the braille one from Brunton, the Silva distributor in the U.S. I have had troubles with the braille compass;the ones I have used broke easily and the locking mechanism on the wheel seems to be pretty fragile. Do you have any other options that you like or any thoughts about the Brunton? I don't mean to put down specific brands; I would just love to find a compass that is durable and that gives the detailed info that the Brunton does. Are there any gyroscope-based compasses that are accessible? How about compasses that blind sailors use? Thanks. Terrie ----- Original Message ----- From: Carl Simmons To: gps-talkusers@xxxxxxxxxxxxx Sent: Friday, May 12, 2006 12:25 AM Subject: [gps-talkusers] Re: irectionality of the POI Kevin, One of the most important areas of providing guidance with any GPS system is that a correct heading must be established. Just as when giving directions to a person the first piece of information would be what direction is the person facing. The GPS system has to determine the heading by plotting your travels over a period of time. This is one of the most complex areas of any GPS system. To help understand the complexity I will try to explain the basics. The GPS system will know your current position by having your location by latitude and longitude. The accuracy on this point is dependent on the current GPS signal strength. Then after a period of time the system will again determine your position. With these two points a direction of travel can be established. Now enters the complexity. Take a case that you did not move over this period of time, but the GPS signal accuracy varies. This will change your position and now a direction of travel is determined with out your moving. This is just one of the variables one must consider when establishing a heading direction. As you can understand the GPS system can not provide accurate guidance until a correct heading has been established. This is the main rule of trusting the guidance is to assure that the heading is correct. For example if you know you are traveling North and the GPS heading indicates east any guidance information could be incorrect. One method I use is to check my heading with a compass and compare with the GPS heading. One other method is to inquire the heading direction and travel a distance and check again then again. When the heading remains the same you can figure this heading is correct. I know this is a lengthy lesson but a very important item in understanding the methods used to provide guidance. I hope this helps. Carl Simmons Sendero Group Training and Technical Support 1-888-757-6810 Ext. 106 carl@xxxxxxxxxxxxxxxx -----Original Message----- From: gps-talkusers-bounce@xxxxxxxxxxxxx [mailto:gps-talkusers-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Chao Sent: Thursday, May 11, 2006 7:30 PM To: Gps List Subject: [gps-talkusers] irectionality of the POI Dear List, I have a question regarding the directionality of the POI's. I have noticed with both commercial POI's and person POI's, for some reason I am getting a off-readings, for example, it will say "Mc Donald's 9 o'clock," when it is really 3 o'clock; I have experienced this with both the commercial POI's and the one's I marked myself, so I am not sure where the issue lies. I am currently using version 3.3, so I don't know if this is a fix that was introduced in version 3.5, if it is I am looking forward to it. Thank you for the information you are able to provide regarding my query. Kevin -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.392 / Virus Database: 268.5.6/336 - Release Date: 5/10/2006