Dave, The location does not vary in terms of its absolute position. You might here that it is to your left, then to your right. However, it would always be at a consistent compass direction and the distance to the location would be reliable. Mike At 06:07 PM 6/27/2006, you wrote: >Mike, if the heading varies during signal degradation, would the location of >what ever you are looking for vary as well? > >Dave > >taxation WITH representation isn't so hot, either! > >----- Original Message ----- From: "Michael May" <mikemay@xxxxxxxxxxxxxxxx> >To: "GPS-talkusers-freelists.org" <GPS-talkusers@xxxxxxxxxxxxx> >Sent: Tuesday, June 27, 2006 7:19 AM >Subject: [gps-talkusers] how to deal with multi path in cities > > >>There is one minor down side to the latest super sensative GPS receivers. >>When you are among tall buildings, it is amazing how well these receivers, >>like the Holux, report several satellites. The problem is that the quality of >>those signals is degraded because they are bouncing between the buildings. >>this is called multi path. The good news is that your position can be tracked >>but the bad news is that your accuracy and particularly your heading is >>degraded by this multi path. >> >>You'll know this is happening when you find your direction of travel swinging >>all over the place. Walk in a constant direction and keep hitting the H key >>for heading and see if there is any consistency or not. If you see 90 degree >>shifts in your heading, you are experiencing multi path. >> >>So I ask myself, "Self, what can I do about heading swings?" First, note that >>the compass direction for your destination will not shift as the compass >>reading is by definition constent. If your destination is reported as >>Northwest, that will not change no matter what your relative heading says. >>You must then rely on this compass direction by either using an actual >>tactile or audio compass to verify your real heading, or determine your >>compass direction from the GPS when you are not among tall buildings and keep >>track of that heading once you are among the buildings. In other words, if >>the GPS heading is going to be flakey, it is up to you to know the compass >>direction. >> >>If you know the compass direction, you can then utilize the other information >>the system is giving you to navigate a route or to use the getting warmer >>method to get to your destination. >> >>Besides the compass direction, you will want to rely heavily on the distance >>to your destination or waypoint decreasing. Even if your heading is reported >>to be South and your Destination is north, if the distance to the destination >>decreases, don't turn around. A decreasing distance to your destination is >>something you can depend upon. >> >>This multi path is not something that will vary among receivers or systems. >>We have tested the $900 Garmin Nuvi receiver against the Holux in this kind >>of situation and there was no difference. >> >>Until you get out of the tall buildings, pay close attention to that compass >>direction and to the distance to destination. >>Mike >> >> >> >>Michael G. May >> >>CEO Sendero Group >> >>Developers and distributors of BrailleNote GPS >>Distributing BrailleNote, VoiceNote, Talks, Miniguide, The Tissot Silen-T >>tactile watch, and the ID Mate bar code reader >> >>MikeMay@xxxxxxxxxxxxxxxx >>http://www.SenderoGroup.com >> >>1-888-757-6810, Fax (530) 757-6830, Mobile (530) 304-0007 >>Sendero Group, LLC >>1118 Maple Lane, Davis, CA 95616-1723, USA >> >>Latitude, 38 33 9.239 North >>Longitude, 121 45 40.145 West >> >> >> >> > >