SP80: High HSDV (HRMS)

Recently (June 18th 2018) I began to hear complaints of high HSDV (same as HRMS) from multiple SP80 customers. Initial complains pointed to a ‘change in the afternoon’ after having no issues in the morning.

I believe that this behavior may attributable to US GPS SV 25 being in the used constellation on the BASE.

If you are having issues with high HSDV the safest thing may be to just turn off SV G25. I would turn off SV G25 on both the base and the rover.

Mission Planning

First off, you may want to check when SV25 will be available at your location. I like the new Trimble / Spectra Precision Mission Planning tool which now works without loading Silverlight (I think it works on all browsers now).

Here is a direct link: [ SP Mission Planning ].

Be sure you get the Position, Time-Zone and Date correct. Once you do, you can use the ‘Visibility’ graph to figure out when SV25 will be available:

Be sure to get the time zone correct or the displayed local times will be incorrect.

SurvCE / FAST Survey with the SP80

In SurvCE / FAST Survey you can disable G25 by waiting until SV25 is ‘seen’ by the receiver and then navigate to ‘Monitor/Skyplot’ and select the ‘SATInfo’ tab. Click on G25:

and UNCHECK ‘Satellite Enabled’.

SurveyPro with the SP80

Go to the ‘GNSS Status’ screen. You can get to this screen by clicking on the satellite icon on most survey screens:

The GNSS Status screen is shown, select ‘Sat Info’ and ‘Show All’:

now click and hold on the G25 box for three seconds:

Click on ‘Disable G25’.

PASHS Command

You can manually turn off the satellite with this PASH command:

$PASHS,USE,GPS,25,OFF

Feedback Appreciated

I am not positive that this is the issue and I don’t know for sure that the procedures work. Please let me know if you can verify (or not) and I will update this post.

Good surveying to you!