<< Back

Upon the recommendation of the Test Review Group, I am declaring the ASOS ACU Processor Operational
Acceptance Test (OAT) successfully completed. Performance of the new processor, using software version
2.7B dated 15 August 2003 (a.k.a. V2.7B-6) has been deemed satisfactory for nearly all operational FAA and
NWS sponsored ASOS, 847 out of 883. There are two small classes of exceptions.

Thirty-four (34) sites await the porting of the FAA's Weather Systems Processor (WSP) function to the new
processor. The WSP function was added to the old processor after the porting of baseline software version
2.60 to the new processor had begun. It was decided to defer porting the WSP function and certain other
enhancements to the new processor until a stable software baseline had been established on the new
processor. A software load which includes the WSP function is under development. A deficiency was
discovered during integration testing. That deficiency is being corrected, and this software load, V2.79, should
enter system testing within a few days. If system testing goes well, V2.79 will be installed at a few OAT sites in
mid to late January. General deployment could begin in February.

Occasionally and rarely, a few sites have reported anomalous high wind gusts. This is a legacy problem, but
one that seems to be aggravated by the new, higher speed processor. The problem has been observed at two
sites, ATT and GSP, during the processor OAT. Currently 196 sites have the new processor installed, so this
problem has affected only a small percentage of sites. When sites experience this problem repeatedly, we
reinstall the old processor. A task order will be awarded this week to Prism Communications to develop a
diagnostic software load for this problem. In addition to diagnostics, this load will contain filters to prevent
reporting of gusts in excess of three times the two minute average wind speed. The task order schedule is
estimated at twelve weeks, making this diagnostic load available in March 2004. The load will be installed at
sites which have experienced the anomalous wind gust problem. Because the problem shows itself rarely and
sporadically, it may take several weeks or months of data collection and analysis to identify the root cause(s) of
the problem.

The ACU Processor OAT began 24 September 2001 using software version 2.6V. The OAT was scheduled
to last about 12 weeks. Two years plus 12 weeks later, and 21 software versions later, we have successfully
completed the processor OAT. The porting of baseline version software to the new processor had to overcome
several unanticipated difficulties. Several instances of unconventional code were found to be time sensitive or
time dependent: they worked acceptably on the old slower processor, but sometimes crashed the new faster
processor. Compilers and code standards changed significantly since the writing of the V2.60 baseline, and this
too caused problems. Other ASOS product improvement software interfaces; for dewpoint sensor, ice free wind
sensor, and all weather precipitation accumulation gauge; were integrated during this 116 week period, but they
were not primary causes of schedule delays.

The ASOS is a modular system, and some system configurations were more sensitive than others to code
errors. By the time of the Deployment Readiness Review on 3 June 2002, it had been determined that simpler
configurations operated acceptably, while more complex configurations did not. This allowed a phased deployment
by configuration groups. The first group had 16 sites, and its deployment began 19 June 2002. Groups 2, 3, and 4
were of similar size, and were added in August, December, and January. Groups 5, 6, and 7 contained hundreds of
sites each, and were added in February and March 2003. Latest approved was group 8 in October 2003, picking up
19 sites.

At this time 847 sites have been approved for ACU Processor deployment, and 652 of them also have been approved
for dewpoint sensor deployment, the balance awaiting FAA FY04 funding. As of 11 December 2003, 196 sites had
installed processors, and 67 sites had installed dewpoint sensors. OATs are ongoing for the ice free wind sensor at
20 sites, and for the all weather precipitation accumulation gauge at 16 sites. Thanks are extended to the many individuals
in the field, regional offices, headquarters, and at Prism Communications who suffered through this arduous processor
OAT, ultimately resulting in success.

Rick Ahlberg, ASOS Product Improvement Manager, OST11



US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
1325 East West Highway
Silver Spring, MD 20910
Page current as of: 02/11/2009
Page Author(s): Kevin Conaty / Sue Murphy		Disclaimer
Feedback