AgTalk Home
AgTalk Home
Search Forums | Classifieds (86) | Skins | Language
You are logged in as a guest. ( logon | register )

EZ STEER test 30 hours non stop
View previous thread :: View next thread
   Forums List -> Precision TalkMessage format
 
alange
Posted 4/22/2006 23:56 (#7072 - in reply to #7028)
Subject: Re: EZ STEER test 30 hours non stop


Sunnyvale, CA
I glad to hear of your success with the EZ-Steer with T2 system.

sometimes there are "holes" in the GPS constellation where there are not enough satellites in good positions. The technical term for this is periods of high HDOP (Horizontal Dilution of Position) and it has little to do with the GPS receiver being used. All GPS receivers will suffer at the same time. These "missing satellites are satellites that are temporarily taken out of service for various reasons, for instance, an older satellite that has a "weak" rechargable battery will, twice a year, be subjected to an eclipse for an hour or two and its transmitter will be turned off and battery power will be used to keep the atomic clock running. If that particular satellite was important to maintain a low DOP, you will see an increase in position noise, which you apparently had seen when it was "off line".

a mission planner is available from the www.Trimble .com web site. you can also subscribe to the GPS advisories to receive NANU (Navigation Advisories for Navstar Users) which report unhealthy satellites. with these NANU reports you can disable the satellite in the Mission Planning program and see the effect immediately on the screen. http://www.navcen.uscg.gov/ADO/GpsActiveNanu.asp and predict when these outages of high DOP will occur.

the EGNOS satellites are currently not used for positioning, they only transmit the differential corrections to the GPS receiver, so they have no effect on DOP

because of the cut back in US government expenses (except for Iraq expenses) replenishment GPS satellites are not deployed until a satellite fails. the replenishment satellite might take a few weeks to stabilise and then a DOP hole could occur for a much longer period of time.
Top of the page Bottom of the page


Jump to forum :
Search this forum
Printer friendly version
E-mail a link to this thread

(Delete cookies)