This afternoon I had a good opportunity to use a variation of the “on the fly” method to initialize a PM2 stop and go session. I have done this under similar conditions a few times with good success so I was not afraid to try it again.

Visualize a 16 acre generally rectangular and hilly hayfield, with various bare branched trees along one edge where the property breaks into residential backyards. The land is brushy at the edges in several locations, there’s a grove of 25 foot tall pines, the hardwood trees are mostly less than 40 feet tall, but a few bigger ones scattered in.

Since a picture is worth a thousand words I thought I would post a screen capture of the Ashtech Solutions screen showing the processed results.

There are two base units (351A & 351B)and the rover. The first “initialization” observation of the rover was for 1 minute 54 seconds at point ID 2000. Previous to taking this observation the PM2 rover was turned on and was collecting kinematic data in S &G mode for about 4 minutes as it was carried across the open field.

I did lose lock at the beginning of observation 0018 near a cedar tree- I shut off the warning buzzer and stretched out the observation to slightly over 5 minutes before taking off for observation 19 in a more open area. This was an inventory and mapping project and is for illustration only. Units are in UTM meters. Your mileage may vary.




Modified By L.A. Johnson on 3/11/2005 at 12:30 AM

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Sorry, I needed to drop the WWW. from the path



Modified By L.A. Johnson on 3/11/2005 at 1:02 AM

perfect site for GPSing. 10, 9, & 8 SVs on all the observations listed.

I see from the Span column that you used your method of starting and stopping the observation times as you felt necessary for the shot; resulting in observations from 20 seconds to 5 minutes. I really like that idea and plan to give it a try next time I use the S&G feature.

My thought with "on-the-fly", was more in tune with being an "equalizer", rather than a method.

The idea being that no one seems to "really" know how long an initialization should occur(other than using the init bar).

It seems to me that if someone ensures that the first few shots AFTER initialization are completely in the open, it would be helpful to the session.

On a sidenote. L.A., I noticed you called your rover, "BASE". That seems curious to me.

Are you aware that if you walk around with the rover but use the time stamps on the non-moving base, that all the S&G points will be "mirrored"(flipped & turned?).

I used to make the mistake(with my ProMark Xcm units) of using the time-stamps on the unit that actually stayed static through the session and found that redoing the session(in A.S.) or just mirroring the results in CAD gave me the same results . . . just an interesting observation about S&G.

L.A.

Thanks

JD

John,

"Base" is the nominal name I use for the receiver. Yesterday "base" just happened to be used as a rover. I usually use it as a base in my vehicle.