ProMark 2 user questions

FTP ASHTECH

HERE IT IS ftp://ftp.ashtech.com/Land%20Survey/Older%20Products/PM2/ i have pm3's so i hesitate to offer direct advice

Time on point is a function of many things. Most importantly:
o Baseline length (the distance from base to rover)
o Post Processing Software (GNSS Solutions vs. Ashtech Solutions)
o # SV's in sky
o Obstructions and Multipath

Post-Processing in latest GNSS Solutions version (recommended and free) will require occupations that are 1/2 as long as Ashtech Solutions.

I would suggest starting out at:

10-minutes + 5-minutes per mile of baseline > 1 mile

So for example:

1 mile = 10 minutes
2 miles = 15 minutes

Don't exceed 6 miles. Double (perhaps triple) all times if post-processing with Ashtech Solutions. Double all times if the SV count is less than 7. Triple all times if you have to walk a long ways to occupy points or if your time is valuable. (Actually if your time is valuable you should consider RTK or a dual-frequency receiver that will process in OPUS.)

You can download Ashtech Solutions from:
ftp://ftp.ashtech.com/Land%20Survey/Older%20Products/Ashtech%20Solutions/
But you may not be able to get it running on a modern computer.

You can download GNSS Solutions from:
ftp://ftp.ashtech.com/Land%20Survey/GNSS%20Solutions/software/3.80.8/3.80.8.zip

Both are free.

The manuals for GNSS Solutions are excellent. You might also checkout the manuals for the ProMark 3. Everything is nearly the same. Which means that my videos:

http://www.igage.com/v/#pm3

will almost make sense for ProMark 2 receiver users.

Finally, once you collect some data that 'works', you can mask out portions of the data to simulate shorter occupations to determine just how long of an occupation would have 'Fixed.' Often the required times are surprisingly short.

Remember that the PM2 and PM3 receivers are single frequency only. You won't be able to use OPUS.

Good luck with your 'New' PM2's! Many folks still claim that they made more $ with PM'2 than any other piece of survey equipment. It is a testament that there are so many in use today.

THANX MARK.

That is exactly what I needed.

😉

Geezer

FTP ASHTECH

The Promark2 is probably one of the best GPS units for the money ever built. They have their issues to be certain, but they work very well.

One of the nice features is that unlike some other units, they will not open a file and begin to log GPS data until they have solved their position. The Promark3 begins to log data as soon as you tell it to which used to cause problem with some of the earlier versions of the GNSS post processing software.

Neither receiver is inherently base or rover, you determine that by your occupation sequence. If you look at the display on the Promark2 after it begins to log data, there is a field in the display that is labeled "Occupation Timer". You'd think that with that name, it would tell you have long you've been on a point. But what it actually tells is how long a baseline you should be able to solve with the data it has collected. This does not consider data quality at all. Experience is a good teacher, in that conditions that do not yield good results today will probably not yield better results at the same time tomorrow if you do not change any of the parameters of the occupation. The thing most folk want to do with static GPS occupations is cut them as short as possible. That is not advisable. Considering the time and effort required to get to a point you want to occupy, it makes good sense to give the time on site another 5-10 minutes especially when you are getting a feel for what yields the best results.

So there are a few practices I'd suggest for best results.
1. The more important it is to you to achieve a good position for the point you are occupying, the longer you should collect data on that point.

2. The more obstructions that are around the occupied point, the longer you should collect data on that point.

3. Depending on how far north in the US you may be, there are never any GPS satellites in the northern sky from the ground up to about 55° from the horizon due north and then in a sort of parabolic curve down to about N 45° W and N 45° E. The farther north you are, the higher that angle is. So you should orient your occupations around obstructions with that in mind. Whenever possible set up south of such things as large trees or similar obstructions. You should not expect good results on an occupation that has significant obstruction anywhere in the southern three quarters of the sky.

4. Since you only mention base and rover, you may only be using two receivers. When doing static GPS with two receivers, you essentially are taking GPS sideshots. They probably good if the vector solution shows that it is but you have no proof of the positional accuracy. To QC your positions, it is desirable to move your base to a different point previously occupied by the "rover" in the first set of points and re-observe the points that are not easily checked by other means. This gives you repeat occupations of those points and allows you to build a network of points that are interconnected with multiple baselines. If you use this strategy, and are processing with Ashtech software such as Ashtech Solutions, you will need to give all occupations of a point the same Site ID so that the post processing software recognizes it as a repeat occupation.

In spite of the book I wrote above, from your question, I suppose you are attempting to use the PM2 units in Stop & Go or Kinematic collection mode.

There are two main ways to initialize a Stop & Go Kinematic session. One is the "book method" in which you use the initialization bar kit. Many people did not use the initialization bar because of the process, in part, but mostly because when the Promark2 with the Stop & Go capabilities in the firmware was released, Thales Navigation had the bar kit hardware backordered for about six months. By that time, PM2 owners had learned other techniques.

If you are on a small site, you could simply reinitialize on the point you did the first initialization on. When initializing on a point you have not previously occupied, note that there is a box in the display that can be tagged designating the point as a control point. You will want to check that box. The only thing that actually does is add the Site ID for that point to a list of control points. Having a point's Site ID in that list allows you to reoccupy that point with the same Site ID in a reinitialization session, something the receiver will not allow you to do otherwise.

So if you are using a PM2 to do topo, for instance, it is a good idea to set a nail once in a while as you go along or occupy some defined point that you could come back to to reinitialize on if needed. Having those points tagged as control points will make that much easier.