Comments on: Improving Position Measurement Accuracy In Consumer-Grade GPS Receivers - Part I

By: igorbrejc.net » Friday Goodies - 01. February

igorbrejc.net » Friday Goodies - 01. February — Fri, 01 Feb 2008 18:57:38 +0000

[...] Improving Position Measurement Accuracy In Consumer-Grade GPS Receivers - Part I [...]

By: Terry

Terry — Thu, 31 Jan 2008 18:20:23 +0000

Let me rephrase that, in hopes of getting an answer:

In areas where there are lots of high-rise buildings, why would you need to use a GPS to get locational data?

By: tough

tough — Thu, 31 Jan 2008 05:59:37 +0000

Because they are GLOBAL positioning systems.

By: Terry

Terry — Wed, 30 Jan 2008 20:00:06 +0000

“it is still hard to position (at an acceptable level) in CBD areas where there are lots of high-rise buildings”

Just asking - why would you need a GPS to tell you where you are in such a location?

By: Leszek Pawlowicz

Leszek Pawlowicz — Wed, 30 Jan 2008 04:28:23 +0000

The problem in areas with lots of high-rise buildings is that they block out large parts of the sky, often obscuring a direct view of many GPS satellites by the receiver. There are ways you can try and get around that, like waiting for a moment when as many satellites are visible from a specific location, through the gaps between the buildings. But even with software like Trimble’s Planning Software (which I’ve posted about here), it’s not easy to figure out when such an optimum condition might occur. Putting more GPS satellites in orbit might help, but there are already more GPS satellites broadcasting signals (30) than were in the original technical specs (21-24), and adding more would add to the costs of the system. There’s really no solution for your problem with cheap consumer-grade units today; perhaps in the future, receiver sensitivities and discrimination will allow them to pick up the faint signals from satellites blocked by buildings.

By: tough

tough — Tue, 29 Jan 2008 23:22:27 +0000

Your observations here are great. But I just feel with consumer-grade GPS units it is still hard to position (at an acceptable level) in CBD areas where there are lots of high-rise buildings. Can you make some advice on that?

By: Leszek Pawlowicz

Leszek Pawlowicz — Tue, 29 Jan 2008 17:49:19 +0000

Thanks for the comment - you’re anticipating Part II a bit, since that’s included (along with several other additional tips).

By: Technolero

Technolero — Tue, 29 Jan 2008 17:29:28 +0000

Les pretty much covered the key points. I would like to add that on a Garmin unit you can significantly improve the quality of a single position by marking the point and choosing the AVG button (averaging on a waypoint) to collect a number of points at that location to improve your accuracy.