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

13-04-2006

Radar stage sensor information Radar stage sensor information adapted* from: adapted* from:

USGS Hydrologic Instrumentation USGS Hydrologic Instrumentation FacilityFacility

Testing Section Project UpdatesTesting Section Project Updates

ICOM meetingICOM meetingJuly 11, 2006July 11, 2006

*(Brand) names have been changed to protect against endorsements

• Instrumentation Development

• Commerically Available Instrumenation (ICOM)

• Radar Stage Measurement (ICOM)

HIF Testing ProjectsHIF 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 HIFused 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 StageNon Contact Stage

4 Models Available4 Models Available

Stage Radars - 2005Stage Radars - 2005

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!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!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 1Radar 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 +/- 0.01 ft <32 ft.

Stage Radar – Brand X, model 1Stage Radar – Brand X, model 1

Walk-in ChamberWalk-in Chamber

-0.10

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0 50 100 150 200 250 300 350Ellapsed time in Hours

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SN 12643992 SN 12639922 (proto) Temperature

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ELAPSED TIME IN HOURS

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SN 1023 SN 1022 Temp

Temperature Temperature TestingTesting

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!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

PlansPlans

Field Testing Partnership with SRPField Testing Partnership with SRP

•Accuracy check over large air gaps.

•Can Tow Cart be used?

Radar – Air Gap

Preliminary Air Gap Results

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0.081

3-M

ay-

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H3611

Puls 62

Arm Height

Brand XBrand Z S

hould

be S

TA

GE?

Pearl River PierPearl 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 FarFindings So Far

Discussion