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<br />OiJQ272 <br /> <br />Radio Rcporting Strc~ Gaugc <br /> <br />Thc Radio Rcporting Strcam Gaugc, shown in Figurc 3, consists of <br />thc HANDAR 405A Standpipc Towcr wi th covcr, mast, antcnna, thc 585A <br />Data Transmittcr, and thc Multi-frcqucncy VHF Synthcsizcd Radio trans- <br />mittcr or thc UlF Radio Transmittcr. Thc watcr lcvcl scnsor, thc <br />HANDAR 436A Shaft Encodcr, is cablcd to a ncarby stilling wcll. A <br />pullcy, tapc, float, and countcrwcight, attachcd to thc Shaft Encodcr, <br />monitor thc lcvel of thc watcr in thc stilling wcll. Rainfall and <br />othcr wcathcr scnsors can bc addcd to this strcam gaugc, as rcquircd. <br /> <br />Figurc 3 also shows an arrangcmcnt whcrc all cquipmcnt is houscd <br />in a Gaugc Housc, which providcs shcltcr for thc 585 Data Transmittcr, <br />thc 436A Shaft Encodcr, and an adcquatc structurc for mounting an <br />an t cnna and mas t. <br /> <br />HANDAR 436A Shaft Encodcr. Thc Shaft Encodcr, shown in Figurc 4, <br />consists of only onc moving part, a rotating magnctic rotor, thus <br />grcatly improving rcliability. Magnctic polcs, spaccd 1/100th of a <br />rcvolution apart providc clcctronic pulscs as thcy pass ovcr two <br />semiconductor Hall Effcct dcviccs. Conscqucntly, accuracy is 0.01 <br />foot for a onc foot circumfcrcncc pullcy attachcd to thc shaft. Di- <br />rcction of rotation is dctcrmincd by a phasc shift bctwccn thc two <br />pulsc signals and a phasc dctcctor in thc 585 Data Transmittcr. <br /> <br />Although thc 436A has a very high rcsolution of 0;01 foot, it is <br />possiblc, using switchcs in thc 585 Data Transmittcr, to rcducc its <br />"effcctivc transmission rcsolution." Thc shaft cncodcr will transmit <br />only on cvcry nth cvcnt dcpcnding on thc sctting of a 0 to 9 switch. <br />This allows, for cxamplc, turbulcnt watcr lcvcl to bc cffcctivcly <br />avcragcd so that radio transmissions arc only madc, say, cvcry 0.03 <br />foot changc in watcr lcvcl. This fcaturc is also quitc convcnicnt <br />during hcavy rainfalls, particulatly in largc nctworks, bccausc thc <br />numbcr of radio transmissions can bc significantly rcduccd, thus <br />lowcring thc possibility of RF intcrfcrcncc. <br /> <br />This simplc, but rcliablc dcvicc has bccn tcstcd and uscd by thc <br />National Wcathcr Scrvicc's Tcst and Evaluation Laboratorics in Vir- <br />gInIa. Thc lack of gcars, cams, switchcs, ctc. in thc dcsign is thc <br />basis for its cxccllcnt rcliability in ruggcd ficld conditions. <br /> <br />9 <br />