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WSRN – Notice of Service Changes
NOTICE OF SERVICE CHANGES – Effective December 1st, 2014
The WSRN is now in its 13th year of development and operations; the dedication of the many
partners (infrastructure contributors, sponsors, equipment vendors, scientific, and academic
partners) plus those supporting operations through annual contributions, have built the WSRN
into one a much lauded example of public/private cooperation.
Several elements of upgraded hardware/software, and changes in the National Spatial
Reference System have prompted the WSRN to make some changes – these will not disrupt
services – but there will be some changes – please read in detail.
WSRN CHANGES
Summary: The WSRN operates dual systems (dual banks of servers and NTRIP casters for
real-time access) and the older of the two systems will be retired on Dec 1st, 2014. A new set of
redundant servers and caster will be deployed at that time to replace the old ones. But, the
legacy reference framework (NAD93-CORS 96) on the old casters will be discontinued at that
time and both the primary and new redundant systems and casters will operate on the NAD832011 reference framework. CHANGES SHOULD BE TRANSPARENT TO EXISTING
ACCOUNT HOLDERS (see the FAQ – frequently asked question – section at the end of this
email.
1. NAD83-CORS96 Epoch 2002.00 will no longer be supported – Effective December
1st 2014. The WSRN constrains all stations to the National Spatial Reference System
(NSRS), via the active control component of the NSRS maintained by the Nation
Geodetic Survey (NGS). The NGS ceased support of NAD93-CORS96 in 2012, and the
reference positions for controlling CORS have gone out of tolerance (due to velocity) we
are unable to continue to constrain to the legacy NAD83-CORS96 Epoch 2002.00
values. The old values are straining the capabilities of the software to maintain decent
solutions; it is time to move forward.
2. No more 156.74.250.185 Caster. The legacy servers and caster (i.e. with the caster IP
of 156.74.250.185, nicknamed “185 server” or “CORS96 server”) will be retired on
December 1st, 2014. Several of the physical servers in this old bank have been running
for 13 years straight, are aging, no-longer supported, and are running an older version of
the software
3. The www.wsrn3.org website will not change. The current website will still offer the
very same static files for post-processing freely and openly to the public (via WSRN
participant logins or “guest” logins) and the “Reference Data Shop” link (one you’ve
logged in) or via the archive at Central Washington University:
ftp.panga.cwu.edu/pub/data/ . There will be no changes in static file formats or files
offered.
4. The Primary real-time caster and Reference Framework. Most users have already
transitioned to the newer “NAD38-2011” servers and NTRIP caster: 156.74.250.108
(nicknamed the :108 server” or “2011 server”) and all stations run NAD83-2011 Epoch
2010.00. This newer reference framework is consistent with the published values for
NGS CORS, the NGS OPU and OPS-RS online positioning services, and is constrained
to WSRN station that are also part of the NGS CORS network.
5. Pending Redundant System caster and reference framework. To replace the retiring
legacy servers a brand new bank of servers has been installed and will be configured
and tested. Users will have a fallback caster (IP to be determined when commissioned)
to the primary “108” caster; all usernames, passwords, mountpoint names, subnets, etc
will be the same. There will be no changes to solution types or formats - users will be
able to switch from one caster to the other by only changing the caster IP.
6. Update Account System. Updated accounting procedures and software are already
running on the newer “108” servers, and there are regular audits. There should be no
changes apparent to the end user. New test accounts have automatic expiration dates
but otherwise the WSRN does not change anything about valid user accounts without
calling the users first. Anniversary dates for all new accounts are at the 15th or month,
with first invoices prorated to the 15th, and existing given a one-time adjustment to the
15th upon renewal. The login databases of the retiring “185” server will be discontinued
on Dec 1st 2014 but all valid logins have been added to the newer “108” server already.
Do not hesitate to contact if you have questions, but please read the following FAQ first:
FAQ – Frequently Asked Questions about the WSRN Dec 1st 2014 Changes
How much of a shift is there between NAD83-CORS96 Epoch 2002.00 and NAD83-2011
epoch 2010.00? It varies around the state. The positional changes in the reference framework
are threefold: the NGS has had improved data, computational approaches have improved, and
the biggest factor has been the “Epoch” change in the velocities due to plate movement.
NAD38-2011 is a multi-year solution, a full 8 years of data and velocity. NAD83-2011 is an
upgrade on many levels; a lot of the noise and inconsistencies in CORS96 (and older
realizations) have been addressed. To give you an idea of just how much velocity can come into
play; in Seattle, over a 25 year period there is a s much as 0.5’ of shift.
Example differences between NAD83-CORS96 Epoch 2002.00 and NAD38-20911 Epcoh
2010.00 run around 0.15’ (in the central Puget Sound area, more on the coast, and less further
east, but this can vary. Vertical differences are typically only a few hundredths (but see entry
below about Geoid models).
What can I do about the shift between NAD83-CORS96 Epoch 2002.00 and NAD83-2011
epoch 2010.00? Most users simply start new projects on the new reference, or localize to
project references or legacy published values – localization, calibration, adjustment (the term
varies in different surveying and mapping software) now is good time to learn how to use those
localization features and establish best practices for your crews. The earth continues to move –
no geodetic coordinates can be truly frozen in time and space.
There are published NAD83-2011 Epoch 2010.00 values on passive monuments available from
the NGS: http://www.ngs.noaa.gov/cgi-bin/datasheet.prl and WSDOT:
http://www.wsdot.wa.gov/monument/ . Note that many of the passive marks were not reobserved to derive the new values, but may have just been recomputed – users have found
instances of differences between observed and published due to subsidence or other
disturbances. Be sure to check more than one monument if using published values.
NGS’s OPUS is another source for NAD83-2011 Epoch 2010.00 positions. If there are no
verified published passive marks near your work area, static sessions of carried lengths
(depending on the precision you require) can be automatically processed through the NGS
OPUS portal: http://www.ngs.noaa.gov/OPUS/ . Note that OPUS-RS will not work for some
northern and western regions of the state, and regular OPUS may not work well in some of the
same areas, and that you may need to wait a day (some CORS stations used in OPUS only
send data daily) and updated orbit data to be used in the OPUS solution. Session lengths vary,
but some users report that 2 to 4 sessions can often match NGS. WSDOT, and WSRN values.
What Geoid Model should I use? It is highly recommended by the NGS that is you are
working within the NAD83-2011 Epoch 2010.00 reference framework that you use their hybrid
Geoid model GEOID 2012A (or newer) as the underlying data is on the same reference
realization – do not mix and match. Though the newest geoid has weaknesses around the state
most early adopters of the 2011 have been reporting improved results for geoid derived
orthometric elevations; especially in determining localized differences.
Will the WSRN turn off my logins if I have not renewed my account? NO. The WSRN will
always contact you first. The only exception is test logins; they will automatically expire at the
end of 90 days – we try to contact you before expiration
Will there be changes to logins or mountpoints in the new system? NO. The same
usernames, passwords, and mountpoint names were ported over to the new server. The port of
the casters is the same (8080) and only the last 3 digits of the caster Ip have changed from 185
to 108
Is the solution different? Fundamentally no, but there have been improvements to the
software and algorithms, plus the new reference framework is much tighter. Uses will notice that
they do not match an old CORS96 value, but that is a reference framework change and has
nothing to do to with solution quality.
Do I choose “NAD83-2011” in the datum selection for my data collector software?
Typically, NO. DC software typically do the transformation from ITRF (WGS84 et al) to NAD83
(Moldensky) transparent to the user without intervention. In some DC software you need to
choose “No Transformation” so you do not do a “double transformation” (as the WSRN is
already on NAD83). Or you simply pick “NAD83” (and not NAD83-2011). If you notice your
results are about 4’ horizontal by 1.3’ vertical off published 2011, then you are probably doing a
double transformation (the underlying ellipsoids are offset by 2m at earth center and around
here the respective ellipsoids are separated around 4’x1.3’).
Does the new caster have Glonass? YES. For several years, all but handful of WSRN
stations have been Glonass capable and Glonass is in all solutions. The few stations that do not
have Glonass are operated by Unavco PBO (National Science Foundation funded) and were
deployed without Glonass – SC03, P401, P402, etc. But this is about to change. PBO is
proposing to allow interested parties to sponsor the upgrade of their sites to Glonass capability
(contact me if you’d like to do this, an investment of that kind would vest a user as a WSRN
partial-station sponsor partner).
PACWA – the new coastal subnet. On the old “185” servers, the NW and SW subnets
covered the Pacific coast area; overlapping at Gray’s harbor. The new “108” servers have a new
subnet for the Pacific coast region; this works better for maintaining solutions and subnet
geodesy as there is substantial velocity and atmospheric effects in that region – better to treat it
separately. (See attached map).
Support of other formats. The new servers will support (as standard services) RTCM3.1 and
CMR+ (though users are encouraged to migrate over to RTCM3.1 (we kept CMR+ for users of
some legacy equipment and RTCM3 (forward) continues to be developed as an open format by
the international RTCM committee). Over the past decade, some users have requested other
formats and network solution types, like mater-auxiliary and FKP; we’ve implemented, they’ve
tried them, they found no advantage over VRS or single base, and then we’ve discontinued.
Other format requests will still be evaluated on a case-by-case basis, but note that users have
settled on these and we can only field requests if there is some compelling need (e.g.
compatibility with legacy gear). As there appears to be no one using RTCM2.3 (and older format
that uses much more bandwidth) we are discontinuing RTCM2.3 on the newer servers.
Gavin Schrock, PLS
Gavin.schrock@seattle.gov
www.wsrn3.org
206-684-5630