Radar stage sensors and other instrumentation issues from the ICOM (Instrumentation Committee) November 14, 2006 James Fallon Annual COE-NWS-USGS Mississippi Valley meeting Memphis, Tennessee

Radar stage sensor information adapted* from: USGS Hydrologic Instrumentation Facility Testing Section Project Updates ICOM meeting July 11, 2006 *(Brand) names have been changed to protect against endorsements

Instrumentation Development Commerically Available Instrumenation (ICOM) Radar Stage Measurement (ICOM) HIF Testing Projects HIF Testing Projects

Timeline of radar stage sensors 1999: Radar stage sensors tested at the HIF, tracked by ICOM. Issues: –Accuracy, range, FCC licensing, temperature effects, communication, power conversion, wave and rain interference 2002: Most technical issues seemed OK, HIF stocks unit, ICOM ends project, asks for more field, product testing 2003: New issues emerge: –Reports indicate accuracy of instrument dependent upon water conditions (roughness, wave height and frequency). –New generation of products need testing. –Does current definition of stage accuracy apply to new method? –What are installation requirements? Apollo rocket inspection building near the HIF used for static tests of radars in early testing

USGS stage-accuracy requirements for discharge computation: The combined accuracy of the total assemblage of instruments, equipment, and procedures… Are to be capable of sensing and recording stage with an uncertainly of no more than 0.01 ft or 0.20 percent of indicated reading The accuracy requirement for any single component generally will be more stringent than the requirement for the system as a whole. …Assessment of error magnitudes and of achievable accuracies of the various system components led to … the larger of 0.01 ft or 0.10 percent of reading as the accuracy standard for the procurement of … pressure-sensor instruments.

Radar measures stage as footprint of a variable area, dependent upon height of radar above water Previous systems measure stage of a column of water above a point Are measurements equivalent?

Timeline of radar stage sensors 2004: ICOM reorganized (elevator music here) 2005: Headquarters issues interim guidance requesting that field: –Does not purchase instruments for widespread use –Works with HIF for quality assurance testing of sensors that are purchased for unique situations 2005: HIF reports: Saturn rocket engine testing pad used for radar tests over water in early testing

Radars still purchased— Wouldn’t you if you had this gage? Trace a ‘best guess’ of gage heights. In some cases the ‘peaks’ or ‘bottoms’ of the painting would be preferred. In painting like this, a trace at about mid-point is used.

Brand X, model 1 Brand Y (2 models) Brand Z, model 1 Brand W (not shown) Non Contact Stage 4 Models Available Stage Radars

Is Radar Good Enough (2005)? Brand X, model 1, problems with accuracy & FCC licensing Brand Y (USA), problems with accuracy Brand Y (EU), problems with FCC licensing Brand Z, Model 1, no SDI-12, accuracy is promising NO!

TWO commercially available models w/ 12 vdc & SDI-12 Brand Z, Model 1 Brand X, Model 1 Both are pulse radars (FCC approved) Temperature tested Lab range tests underway Radar Stage – New Models!

Vendor consulted with HIF on new unit development Pulse radar, low power Battery power (12vdc) & SDI-12 Spec accuracy +/-0.01 ft <66 ft Units arrived early 2006 Radar Stage – Brand Z, Model 1 New Old

Vendor has discontinued old model Demonstration sites at USGS Water Science Center stations Battery power (12vdc) & SDI-12 Spec. accuracy of +/ ft <32 ft. Stage Radar – Brand X, model 1

Walk-in Chamber Temperature Testing Brand Z Brand X, model 1

Is Radar Good Enough (2006)? Brand X, Model 1 accurate over temperature range. Brand Z, Model 1 working to improve units. Waves and sampling rates may affect accuracy. Air gap testing over larger ranges needed. MAYBE!

Radar Measurement Questions Do waves bias measurements low? How does measurement timing & sample length affect accuracy?

Radar – Wave Effects Investigate effects of waves on sampling rate & accuracy Construction of wave generator Modification of existing test stand

Horse Mesa Dam Reservoir drawdown fall 2006 Brand X, Model 1. Brand Z, Model 1. Brand W Remote camera & weather instrumentation Instruments sent to AZ SRP making mounts Plans Field Testing Partnership with SRP

Accuracy check over large air gaps. Can Tow Cart be used? Radar – Air Gap

Preliminary Air Gap Results Should be STAGE?

Pearl River Pier

Radar Stage Measurement Horn antenna Temperature may affect radar measurements. Sampling period affects measurement uncertainty. Radar possibly biased “low” for wavy conditions. Radar is less accurate when air gap increases. Site licenses can be needed for some radars Findings So Far

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