Trimble Planning Software Timing Error?

[Badmachine]

It has been said that when reviewing Trimble Planning Software GPS/WAAS GDOP and satellite visibility data for a past date and location, that the times presented are inaccurate by 30 minutes due to a software error.

Is this true? Is there a way verify the software's accuracy?

Also, is there other software or sources for GPS/WAAS GDOP and satellite visibility data for a past date and location?

Thanks.