CA2480621A1 - System and method for fast detection of specific on-air data rate - Google Patents

Abstract

A system and method for fast detection of specific on-air data rates are disclosed which, in one to example embodiment, enable endpoint devices in automatic meter reading (AMR) systems to quickly determine the existence of over-the-air information that is specifically targeted to a unique class of AMR devices. An endpoint device utilizing the digital squelch circuit arrangement and algorithm of the invention can quickly and precisely determine if the AMR system is communicating with its class of AMR device by looking for a specific non-standard data rate present on the air. This method therefore allows for a significant improvement in battery life in two-way RF communication units by avoiding unnecessary data processing and data transmissions. The digital squelch method also enables even faster determination of inappropriate data rates and of no signal present situations, further improving battery life.

Description

SYSTEM AND METf,84D FOR FAST DET.B<CTION
OF Se$t"BFIC C11~A~R DATA RATE
This boa claims tire bme~t of U.S. Piovi~mal Appticauon 1'Jo_ ti0/500,507 filed September S, 2003, ~ 'U.S. Provisional Applica~on No. b0I598, p 58; filed August 2, 2004, v~hich sre incorporated harWa iu Chair eatira~cyy by ~t~cc..
A compact disc crnatafning codes eud infouu:lion describing one e~zba~d~nt of the imrdisclosed herein is e~ubmitted herawith and is hrreby incorparstcd by rafc~enoe. The compact disc comtains fho fotlowingPro~ns~
SIZE IN BYTE9 DATE Oh' CREATION
decada~rh.txt 1,485 08J31l04 FIagMasks.h.txt 13,683 08131104 functions,c.bct 98,985 08J31l04 fiuiaioms.h.txct 3,341 0$/.31/04 C~IoW_Fsi'.c.t~d 7,776 08/31/84 Gold l~.h.t7rt 6,?28 08I3II04 ha~warc.c.txt 34,zsz osh ll04 ha<dwaub.h.txt 2,559 08!:3!/04 init.b.txt 1,769 081:31104 hu~rupts.c.txt 22,679 08la 1104 main_flmCtionsc.txtx3.'7!6 08131/04 Main ifimctions.h.txt1,530 08/31/04 Mcasagea.ctxt 29,597 08!31/04 M~ag~.b~t 1,308 08131104 Paramoters.h.txt 6,910 08l: X/04 PinMas~sh.txt 5,096 0$;131104 protocoLc.txt 44,724 08/31/04 protoc4l.h.txt 1,598 08l_ 1104 rotate.a43 1,008 08!:1!04 TIC 111Yl~lOn ~Bl~ J! t0 ISdiO ~ (~ I~li~lillt'.atlOn sy~8, 8~
more particularly to RF ca~omunic~taout schemes used with remote autumfttie m~
reading (AiVQt) davires and s~rsteme.
Antamaiic meter raading (~MR7 systaans are generally ~wa ~ the art,. Utility cump~ios, for axample, use AMR syateues to read emd mosiit~ ~tomor matins re~otety, tYP~Y ~8 Tea ~!' (~ tiaaas. Ah~t sysE:crns arc fava~a~,~od by ntiMy com~pa~es and other nears bacause the systems innrease the e~cieac~y and aoenracy of collecting tead>ngs ~ maaagittg austoaaer b~7ling. For axampto, teeing an AMR aya~m f'mr the monthly reading of residential gas, cleetria. or wator metsm diminatvs the ueod fir a utility rmploycc to PhI~~Y each ~ ar brwh~e a meter is locatod to a a reading by hand.
There ere several differaaa~t ways in which cmrraont eyat~us are config>uad.
hn a fixed eaedpoi~ot dc~vicae st meter tocalaio~ ooa~mmnicato with readers that coll~t readings and data using ItF. I~ara and throughout this documerr~ the term "ayoidt device' grill be eesod to gmually refear #o the meter and mabor intar~ae unit that ~ with the reader ~s a sie>gie device, although in vsrioue ombadimants the ~meltr and zuxetxr iateri'ace unit may be dasti~t devicca is dcctrical commu~icatiom but xeot physical proximity with inch ot>mr. Tlvcre maybd multiple 6xod irrtexmodiate readers located t>mnug>xrut a largor geographic area na utility poles, for racample, v~rith rich eoac~oint dovice associated with a p~ readm-acrd each raade~
in turn communicating with a cee~tral system. Other fi3cad s~rstcms ntilixe only on~ central reader with which all cndpoint devices comtntmicste. ha a mobile aavirat~cnt, a handheld ox otherwise mobile reader rwith RF communi~.on o~abilitiea is rraod to 4;olloct clefs from aadpoint deviccs as it is moved from place to place Ug. patent No. S,9I~,673, far ~c~ple, rolaroes to an AlViR of t~ type used far reading utility motels by usi~ag a axed R,I~ networlt. The is a network c~prisai of tstultipIe ceIt3, with each colt containing s siagla data conaentratwr emit and a typically Iarga aemo~ber of meter interface mrits. rn ope~iosr, each matae inteirface wait is aseiguod a Zmiqna time diaplacatzuuet number sad responds to a mfr reading request finim a data oo~c~atar unit booed r~roa i~ time displacement muuaibear.
A aoncara rogasding both fixed neivrom~ and mob~e env$oanments is endpoirot baEtery oomso~tia~n. Each endpoint davioe is typically ~ipped'a'ith a battwy powered mete ia~t~face twit that co~~ with the reads. To cwatn'bute to the ove~l system goal of inc~aed a~eicaacy and accwacy of motor rcading, it is desixable to prola~cg tba meter mt~fsce battery Iife to ralu~ time and experasc maiataimdng and eervneing the battaxias io the meter iata~rfac~. : ince using a battery with a larger capacity is gully teat a viable option doe kr cost and space oons~~deratio~ne, the pmethod with which to inareaae battery Iife is to race batty causumptian by the m~ ia~rfaca This goal may ba lobed inn paxt by operating the melee intn~c~c in a "sleep" or rcttuced power modc when caa~aiaation wig the rnaadezr is not ex~octed oor required.
'fF.S. Palest No. 5,726,646 ~ directed to s metlwd and atus for a~tivatiag and accessing remote meter i~aterface device. A raadiag device initiates comuxunicatiozs with a meter inte~ce nit by transrnittaag a request oa a Commcmicatiore chmaL ~'ho naeta inta~r~ce emit is operable between an active and inactive state to reduce power ctia~a ~d _ _ _ ..____.___..~.~z..~~ a~~~ ~ .~.._____ _____._~$ .~r.______ _. _ is periodically activated to monitor a commuaie~iau channel for clraand activity. The request tom the motor reading device includes a twit idea, and the mater irrterfaea uauit is activated at a particular tuna period and defeats communieatiou ackivity oft the cot~municatlon channel originam~g from the n3eter reading device.
Other moods of reducing battery consumption have also been atternprcd is which the endpoint devices reaportd only to eignaia above a partiouler threshold os only to signals that include some type of system identifier. These methods help to reduce power oonsnmption by limiting the signals that a point device will respond to.
U.S. Patent No. 5,684,472 a dirxted to a method andl appaxaius For r~aas~taly scce~ng relater status information int a meter reading system. Courymuu~icatioxis befiweare battery povvaured meter interfaea units and a meter reading device occur at a f rat data rate, wbdlr: cc~cationa between, the axtemally powered meter inoar~ace amts and the meter raad~g deco ocetu at a second data rate di#farent than the fast data rate,. Communications betweeu~
battery powered muter in#erlhee units atLd ra~ternally power mater interface nuns occc~r at diet rates so that more f~ue~t communication with externally powered mater intarf'aoe units does not rtst~lt in extmdod receiver on-time for the battery powered meter iat~r~ce unats.
t3thtz sys<ema use analog aquclGh techniques based on received signal surength iudicatQrs to ptc~e battery power cox~sun~iorr. These methods" however, are prone to falsiug because of intcrferemce frarn other sources. It is also di~cutt to net the received signal strength tT~ahald level a~tuutdy in systenos having many endpoint devices because tire envi~rneutar lions vary at d~rmt locations and change over time and te~auperataro, vrhich cannot bo easily ar antocally comp~satect for 1~y the gyatem, This leads to the setting of citluer aft artificially high threshold value, which will miss some endpoint queries and lower system duality of service due ~ the roceiver tlnreShold being about #3~e noise floor, or the of a log-thold. whiclx will dcpIetc the battery due to excessive faking.
Sy~stmas iu which the a~pomt devices look tbr a speaiizc Byate~ i~fiGr in the de~aodulatad data inquire that the endpoint receiver be brought up loctg cnaugh to racovor data and satciave bit and $ama synchra~on. This depletes the b~dr~y is a aycte~t is which the ~ m~vet mud this pco~s ove~ry few seconds.
There is, thar~e, s neod in the industry fos a sysocm and method of opor~g AMR.
sysboms fist eons battery li6e ~ovh~C :rot ea~i~cmg commuaieatioon capabilities ar parformaace.
gY of The iuaveuntioa disclosed sand das~bad he~ia substaatiaily meets tixe;
afiareanaationcd naods of the ia~s:ly by providing a syabeaa sad metimd fOr fast detection of spec o~a~arr data rah. In one ombOdiment, the s~yst~ sad taethod aaabIc an endpoint davits to quickly deteanmine the cxistcnca o~f over-tha.sir ~rmation that is spacifioally targeted to a pique class ofAZum dcvicea. ~'he 1 sqnclch system sad the metf~od of imple~men~on conaGCvc bsttary life is the endpa~t device sad $re Tux impmvemart over prior art at~Iog squ4lcb sy8tcms acct methods that o~nFy laolr for the presence of as J~F si,~nal over a specific tbarvabold.
~ are embodiment, as mdgoint device utilizpag the digi~l sqnelcbWitry 8a<3 a~tg~oaithm of the invention can qnickiy and precisely doterDnine if the aystsm is cozmnunicating with its class of A11~, device by Iooicing for a spaci~c non-stmndrrd data rate prat as the aim This mad tberofore allows iior a s~adficaot impravemmt in ba~ry Iffy is two-way gnats. The digital squelch technique can be cxttensied to multiple similar data rates in the eatne goographfC srna to aid device bay life. This is accomplished beeau9e the digital squelch method is seas~ivo Over a vary narrow range,.
allowing for multiple unique classes of point devices with very e~ilar ~tF sad data tr~anafer pdtfarmance. Further, the digit~tI a~ucleh method aoables even faster detorrninadon of insppropr3ato dote rarer and of no signal prat situations, is which case only noisy would bo da~ctsd.
1n operation, aatbodiments of tho digital aciuelctr system and method arable an t device to eval~ the data rate of you inbound signal and qadCk)pr de~~ne if the sigaat has the c~ct data rate 80~ a epee s of dovicea. This is an imprnvnmoa~ ova the prior art becaase it dose root xequire bit c~ $~ma~e aynudnmaizatio~a to cpcrate p~opealy, malting it mush ~stev thaw tire na~eprevj4usty died. Ttie medrad echo does not dopa~d on the Ievel of ItF being iaceived. This enables tho system to operate well at low signet levels, avoiding false triggering at high ding signet levois sad ma~g it well suited to l;;iM bands or is licensed eels where n~ong adjacent ~ iatmfexence maybe eancounnteted.
Tho above vary of tlzc mve~oa ie not ~ to describe aa~ch illusksated Scot or every impleancntation of the invontiar: disclosed horoirt. Z'ho figures atxd the detailed doseriirtiaa that follow more particularly exemplify these embodime~.
8$~~ DBS ,SON OF TIC D$~,_WlhTf3S
The invrartio~ may be ~rrc completely Mood in con~ida~tiaa of tho follovviag dotaited de~iptioa of vsuious embodimo~ of the invantiam in co~un~tiam wig the accomp~ryirrg dra~~g8, ~uu which:
FZ(i. ! is a $ow chart of sae example embodiment of the digital aqudch rnathod of ttte iavenfion, "a.~Y.~ ~ ~.»a.~a ~.M~..... ~_---.
. .. _..,.. . . M~:,:~. ~,~ ,.T.~,~m~ ~m,M v.m.,~,. ~. n FiG. 2 is a ma~iag diagram of oae example aribod~e~t of taro digital squelch method of the inve~ation.
FIG. 3 is a flaw chart of a selectivity last in acroxdancx with o~te example ambodimmt of the tion.
FIG. 4 is a hardware schematic of a deal wfgdower is accordance with one a~cample embodiment ofthc imrention.
FrG. 3 is a hatdwsra ~c.c of a divider circetit is at~r~dsnoo with one example emlwd~ment of the inventtou.
FIG. 6 is a ltasdwsrc sch~atic of a daaoaer is eacx~mdarLCwwith ans ex~glc ent aftlt~ invr~oe.
Wlaule the invea~tiion ie ameaable to visions modi8a~oo~s and aiternat~iva forms, special f~tnof have beeon ahovro. by way of to in the drawi~~ and will be de9~ibed in detail. Yt should be u~de:atood, hovvevar, fat the fan is not to Iimit tht: invention to t'he particular arrbodima~s d~~bed. On the ~, the iioa is to coves atr axadificationa, equivsle~ts, sad eltemataves falling withia the spirit and ~pc of flee ~ventiaa se dcfened by the appealed claimso DBT~ DBSC;RWON OF ~~~t,~
Imgl~ao~ton of the digital squelcxt xncthod discloaecl and de~"6od hera~n pmovidea a more xvbuat AMA system with hid qe~ality of ~a~rica while alga reducing costs by incteasing battery 3ife in aadpoiat dcvi~s, Th:c iavention can be more readily uvtierstx~od by ~ to Fib 1-6. the folloariug das~tionb and the aocompiimyiag compact disc and its cod as set forge above. While the imreaatia~ is avt aeeeaaa~y lmnited to such arl ~ication, the invcatioa will be bona agpreciabal uaianxg x diacuesian of Vila dmbodin such a sperafio context.
Aa briefly deaalbed above, AMR syst~e typically cozr~r~sc a plurality of aa~po~t devices, for Gxannple utility c~su~ion m~ers, goographicalty distrt'butcd in a local area.
AMR eyatesns are typically most tts~l in t~eaida~ntial ead bnsi~s anviranuu~ts in whic~6 meter densities at~o relatively high and in which it would be costly sucl tiazo-consuraiag for a utility empto physically visit each mater. A relatively largrs geagraphie area, fc'r ~am~plo a city, could include mare than one AMR sy~an opaatiag in close goographic and oomcaa~ioative pxo~i~r. Jet A'~tt syrtams usiag R,l» coatmtuticabaa schemes, each oadpoint device is in riectricad oonuttuuicatiom with a hued or mobile relda air as intatmodiate e~o~t davioe to raudnely collect md~ readings ead exchange data arid other information. Iv areas is which momG tba~t ate AMA system are opt or in app»ioma in ~wluieh the reefer is roq~a~g com~catian with specific devioea, each eadpoiat devico meet detr~muiue vrhctha~° ovartho-air comr,nunications era directed to it ar to its class in order to properly xsspoatd to tb~e como~mut~icat~n, The digital squel~. method of the ~avc~ntion described hceei cr eatables A'NBt.
system endpoiat devices to quickly and e~raently analyio over-~e..a~C
aaumicatio~as to ic~ntify those commu~nioatiam~s that are targ a partiGUlar device or class of devices.
FIQ. 1 is a llovr chaff of sac ale embodimetrt of a distal squelch ident>&oation toclmiqae 100 of tbt inrr~tion. Digital squelch t~niqne 100 is imptd by catch of a p'ltuality of micrcptncessar circuiuy eqnippod andpoiat devices opeuat5ng 'within a fixed. acbwark AN)lt, system utilizing RP commumcaiions foot data gathea~g sad transfer, ll~ore particularly.
the digital squelch idetsi$cattoa ~ providos i~ faSt don of a spoci8c M~mchestac an-sir data rata that eaablat as !~ndpofnt daviaa to quickly determine tk~o cxiatesxx of ovar-~e-air information that is specifically tacOd to its mtiquGe class of A,M~t dwice8.
Tecianique I00 is impl~te~d to eriah endpoiat deviaa when an itF sigtsa! is ducted l0I to date~ne whether a rcaponse or other action is roquirea. In i~aliiza~iion shop IOZ, d~point davits pons and timers are set tip apd a capt~u~cJprocess is era~ted.
Capturda I04 is the step tb~at fvlkrwa is rovhich tba digitat ~uelcst ikon or $ltddng p~vese takes place sad is dracdbod is datail below. If a valid signal is defeated by the eadpoiat device irt e~p 104, the digifial ~It~ering psncess ie toW natod and the decoding ptncess is initiated in order to act upon the dated a~nag. A
valid sift is ane targctiag a p~racular mdprniut device or device class. ?f a vahld signal is act defeated in step I04, the digital squelch fltating pm~as mds sad control ie passed beak to tho csdliag functioa With 8 "Tlo '~." 111d'lCat~a~Il. In ~e 8~o~lc~t, a '~1~~ fZ(~~» CO~ltlfi'D~ Is de~nll'1ed ~ ~l~~Ya ~ t~C ~ of fait $,~peGtOd bit lVidulB 0t 1098, a~tl th!! ~pD'lt deYlCe p0~i11e~3 down quickly is to ca~nserve battery life.
Doting the digital squelch pad of'proceas I00, hardwata and software aseociatrod with captnndco~are i~axapt step 104 collocts alga and aotrts the ~mea~taurps in order to detex~un,a whother the inbound signal contpriaas a particular non-staadaid data talc. If the appropriate nam atat~daid data rate is detected, the inbound signal ie directed to that garticu~r eodpaiot davits and lb~er co~nunic~ions, ~or ~camgle an ~bo~tad sigaat ~inatuding a conatmaption are initiated as deter by the inbound signal contents. When flue endpai~~t device bagias pig ~ ~8~ ~ ~P~ct i04 is tosnerl off and a Ti~m~ A of interrupt tttep 1 Ob is ttmted om~. Timer A of intta~rapt lU6 is used ~a ma~~
a ~anchr bit fianu.
In one example ~nbodiment, the value for the start of the Manchester bit frame is Ioaded into a register at the end of a successful digital sqprocess. This value is used to tuna the start and sad of the Manchester bit fx~n~, whea~e pteaee was determined in the sqnelch p~roc~s. Fig.1 also illustrates a ro-~pliag loop 108 for sampling of the i~omiflg data ra0e uat~
ago mare samples arc needed ~r reqae~ste~d.
Flti: 2 is a tia~g diagram X00 of one embodiment of the digital squelch, method and system of the in~tion, wb~in fha system is configured at ceptm~alcompare interrupt Step 104 to coIket edgses and sort the th~eetampe as ~Ilowe. In one aoubodiaxent, all communications frame the cesatcsl radio to the a~o~»t devices i~ the sysbdm are Manch~r-e~odod.
Manchester estooding is a eya~chranaus cloclmeo~codang techaicluo need to e~do the clock and dad of a syne~ro~ons bit a~am. Aa used imccin, s ll~llauclroSter bit frame is dafmad as the period of ti~aaa from the start to the end of ono Manridata bit fn one ~ni~odiman~
and i~
acoomdance ovitb Mara~bester encoa trenaiti~ must oocnr is the oan~ of the Maacbe~sbar bit Frames. At a distance of one half b'rt tern a Gapturad edge, there mar or may sat be a transition, as the edge may or may act be is the middle of the Manchester bit. A, fhll bit is the tuaae from thrs amrt to the Gad of otar M~ dgta bit. ~ ooe easmpla mnbodimmt of the dig'aat e~t~h method of th,e invention, t6aro should be a transition at the full bit point.
A base edge is the tuaaestamp value of $~ edge finm whadi the next edge ix moasarod, sad a uax~
odgo ie the $ret bs~e edge. Bad edges are the total odgesa first do riot fall into a half bit or a fall rsit category from the start of a doto~n cycle. Good edges are the total edges that fall into the half bit or H~ll bit caxegory from the steer of a dotoetian cycle. ~4 good phases cou~,t i~a tho~s the total. number of good edges that qualit~r as edges ti~at can he used to determine phase; for ea:ampte, tv~ ~ edges roooivad than arc one ibll bdt apart and harry ~ edges bexween them an two goad phase edgy. In other embodiments, non-return to zero (htIiZ~ yr straight binary esncoding is weed.

Ac~O~'d:ngly, 811 ddgG 8t $10 Matt ~Df a A 112 Is a b~IC 0a~e m tlla C~di~laa'k Df FICh ~. An ~edga ddected during A I I2 occurs tnv soon. to bo s good edge. If as edge is dcteeted, the bad edge count xagister is incrameated aid the good phaso count register i$
cleared. A good haaf bit occur at timefrauw $ I14. The good cwt is lac~cnted end the edge a# » 1 I4 the brio odge plus a~r minas half of the error. If the previous good edge arses not a poseiblo clcxclc adga. thm #ia cnamt edgy. 'b~e~ a po~'ble clock edge. An edg~a detected du~a~g tiunefraoaa C 116 ova too Into for a half bit nad too early fvr a full bit. At C
I 16, themfvra the bad count Is iac~r~n~ted suaud tlbe good phase eam~t is Glossed. A, good .thll bit occurs at ~ocma&amc D 118. The good ~nnt and, the good pheaa cvxsxt are iacreaaon~ed sud, because this is a vlvck edge, the edge is~ D i l $ bthe base edgy plus or micas half of the ernor. An edge vccuuing daring timeframe B Z20 occurs too late tv ba a $iil.
bi t. '1~ bed coast is iacrand this edge is the base edge, or zoeo odge. The phase count is also claared.
Altar es~ edge is eollectod as above, a test is perFOrmed to imp~ro'ro sel~ivity ~ mope a~uateZy data~nino detedaion of a valid sisal. FIf3. 3 is a ~owch~.t of one oa~la eanbodiment of this selectivity mast 900. First, the timing b~vrr~. the base edge and; the zero sxlge is analyzed at step 30Z. If the vs~Ina rasnItiag ttop 382 is witbia as acceptable lGrnit at step 304, the bad. edges are tbert revieared at step 306. Yf enough bad edges lsaee beozx detected itt step 3fl6, ~ rralid ia~ag signal is prescc~. O~wisc, the good ridge cxmnt is than ea~alyzed at step acs.
If test 300 is porPotmed silly, tho inbound anal is coasiae~d valid and tho receiv~ag dewica bogies pu~ocassing the iaeoming sigaat dat.1 at atelr 310.
ReFardng again to FIa. 1, when tba endpoint clevioa begins pmces~g incomrag sigeal clefs st step 310.
captaurdcompara intarrupt operation at step 104 is ttuned off and ~e Timer A
of inta~pt step it lOb is tinned art. T'°un~ A of iri~mpt 14b is uae~d to mark the l~nch~ester bit fratrte. In this example embodiment, the value for the staff of tltc M~tnchr~c bit frame is loaded into a register at the cad of a successful digital aqnelch process. 'This value is us~t to time the start aaud and of the Manchester bat frame, where phase way ~,damir~cd is the sqaclch groccas.
this oaet3tod, t$e e~poiat dcvica is able to qaickiy deterardno wtutTu~ over tl~.air iteration is teeing targeted to its mtiquc class of Al~i. device thtauglt the specific amt-air data rate of the signs! date~od as desaribad above.
FIGS. 4_6 are ixardware scb~atxc~ gtmad in ~mocondanee with one 1e embodiment of the inver~tioa~. Iu pardaulax, FIG. 4 is a ha~ware sclhematlo of a dual windawer (or aige datoc~ar~; FIG. s is a hudware sehemta~ic of s divider circuit while l~G 6 is a hmdwa:a ~a of a dxoder in aooordance wsth one exaaxple emhodixaemt ~of thv iuvrn~.
Refcxring rtaw ma'se pa~cularly to sage dcboctar circuit 400 of FICr. 4, raw data signal 402 is clocked into a aloft rc404 at a rate mach higher thaw the data rata.
Signal 402 is a qaantixed or clock syacluoai~ed versioa of clefs oat of a data sliccr (to FIG
d), yr a receiver rduming a digital data stress. Shin aegister A~4 is used to daisy signal 4Q2. The delayed data is that presentod to a 2 bit EX~LUSi'VE-OR gate 40b, which date trendtivns, or edges. Windowvs are fblmed by counters 408 and 410 to evataate the data ions to astemai~xe, similarly to the software approaclw desctbed above, if the data transitions fall into '°,good" windows or 'i~ad" wiadnus. age dateotor cir~atit 400 also roceuves its cioeJc signal 412 flan circuit 500 (~c i~IG. S~.
T'iws, in qparalia~, a good edge is delved and then the amct several edges detected are analyzed to detarnnine whether the edges fall writhin "good.' wi~vs of where the edge would be expected to be if the defeated signal is at the dais rate being sought. One o F the goals i8 to accwt~ulate a sat namber o~ good traaaitions, or ttions that would o a data rate, bcfvrc accuaaulatiag a sat not bad t~itione thak are transiticos occ'de of the windows accumulating gmod ca~mte. If a stibeeqtuxt edge falls within a wmdovb, saunter 408, tlro "8aod cxnat," is sued. If aai edgy falls outside the: vvindcw, it is a x~ camuer 418 ie iu~e~ If aomrter 408 reaches a spxiiled "good" value b comnot~
410 a sposii~d 'bad'° vala~ circuit 400 inQicates that a valid data rata is ~ Yf cauatar 410 re~es its v8tue before covatec 448, quit 400 i~adicatess that as invali i.a. a data rata that is not the pre~red or data rate, is pry whxich indicafes bo the sysGGm that it is wanecossary to a~uc ao~uiaiticuu. ~°he systaot w~l also cease sad saalyxing edges if d prodetereuoad acqmisitiort #meaut is xeachcd in which no e~alid rate has bees de~ct~.
fuse wiudo~w widths or aim am adjustable and ca~stomizabte sa as to allow talaag into acxount bit sifts sad otlaor a~malies, allowing ap~innizaticra of flat aau~vity and rate.
The goad count and bad count values era also adjustable so as to c~imiz~e tradeoff's betwcar speed, ~sitivitY, pnweor cons~ption, sad false rats among ~thec para~aters.
The data rate and oiber related parameters are also c~e~izable.
FIG. 5 ie a divider s~.roit 504. Giremit 500 derives the n~aesry elaxk to drive the rest of the ci~try. For example, circuit S00 receives sa are input a I8 clock signal 502. TK FLLIp FLAP 504 sad D FLIP-T~LOPS Sp6 ~d 5fl8 of circuit S00 pro~d~ thrGa output clock 8equancies in one embodi,~t: a $66 kflz signal 510, a 3:.6d MH-r.
signet ~12, sad a 6 Mlix signet 514. 'fheso are exema~tpIary clock yes of ante ambodzmern a# a ~atticular data rate, I~ttrcvar oti~r data rates may use differntt fraqueavcics without de)>arding &~rn the spirit or seeps of the invention.

FIG. b illustsatea a dr circvt 5Q0, which atdr~ls and traclCS clock and data out of the incpmiag raw data sig~nai. A sliced data signal dOZ a»d divided cloak sigpal 604 serve as inputs m ra~rc~ut 600. Output raw data sig~nsi 50b i' fed to alga detector cit~ii 400 (eax FICI. ~).
Decoder circuit 600 pmvides a rxaverod data aigusl 5eI8 and rocove~d clorl~
signal b10. T7io ion in ai~aIa 608 and 610 is used upon drtection of a valid inoa~g xignat data rate by circsut 400.
The above.d~e~oacibod imple~ne~ticm of one axamplc wut of the digital squelch systecu and mend of the inventiau e~ also be de~'bod as a floating wi~ovv for tha d~dion of new goad edgas, s new good edge is used as the beaus for t7uoding tha matt good edge.
TJxoa, the good wi~aw Lands to float along as ua~~r good e$gex arc found. ~
anothar enubodiment; a first edge is dcxeeted mad all Bcllavving aigea are timrrstean~d and eked to the first edg~a. Modnlo arithme#.c is used to det~miaa if the subsequent edgy are ratdtiple~s of tbat fret edgc and to thcn'bwld au array of edge time. Zf the first edge fails to be a g~oroa ed~g~s wheuo t3~are are no other edgas or not enough othaor edge are multiples, then t~ first edge can be discarded and tha procosa repeatad using tho saonnd edge, tfiird alga, etc,., up to as xaaay odges as the CP'UwilI accommodate.
In apemdan, ttre digital squelch scheaoe as desaribed above in one Ie embodiment is implementod as peat of a iced n~wor~ AMR systean or in a n~obilo metar=~d~ing envi~~t. Far example, in a mobile anvimmmaat, endpoint davices may bo locates, in rasidemial lamas and a reader may bs loci in a molrilo utility velucLe that drivos dawn its adJaeent the ~idcnaal to collect readings. In such a syate~n, the method of the invention caablea the reader to qtnickly and accu~eyy anliect anud data 5v~m ayy$ta~, ~.
If the utility vehicle is moving at a sprat of about t'hirtlr miIea per lwur; tha vehicle wiU travel ~P~Y ~0 foot in tx~n seconds, The wt~ucle will h~av~e a communications redit~s of xi~tdy 500 foot with the expdcbed power levels and ancedvox ~sens~tivitios in one embodiment. Each endpoint devico will, on average, be in range of the vebiclo for approximately twdwe to twenty-flvo aa~ads in une em6adimaot. Tl~is is a sufficient amount of time tv wake rip the endpoi~ devices, id~il~y arts x~oquost s rxtobile data packet be seat, xoccive the tnabile data packet, and, if aocr, potrstt~Y 're~rY the 'ratuogt and receive portions of t3~e digital squelch she. In other related eanbodis~s, the digital squelch system and method of the invention is got icily limited to the e~ocdascn'bed shave mnd caur ho modified for ease with di~aa~t frequencies typically used ixi other Norm Ameaic~n, European, a4d. othdr iatoo~cadorui Iocatians.
The invcntioa may be eaabodied in c~Or c forms witb~t departing from the spirit of the essential attn'butae~ the~eo~ ihero~ora the illustrated embodim:ctute ahou.~ be c~naiderod in all respects as ilhtstrativa and sot restrictive, refcat~ance being made to the appended claiums rather thae~ to the foregoing ion to indicate the scope of the inve~ion.

Claims (24)

1. An automatic meter reading (AMR) system comprising:
at least one meter reading device adapted to transmit radio frequency (RF) communications; and at least one endpoint device having a meter interface in communication with a meter device that is adapted to received RF communications, the meter interface module including a digital squelch circuit arrangement adapted to be responsive to an inbound RF communication signal with a target data rate that corresponds to the at least one endpoint, the squelch circuit arrangement further adapted to detect the data rate of a plurality of inbound RF communication signals and determine if the data rate of any of the inbound RF signals matches the target data rate, wherein the meter interface module is adapted to transmit metered data via an RF signal to the at least one meter reading device when data rate of the inbound communication matches the target data rate.

2. The AMR system of claim 1, wherein the RF communications Manchester-encoded and the digital squelch circuit arrangement is adapted to detect a specific Manchester on-air data rate of the communications that matches the target data rate assigned to the squelch circuit arrangement.

3. The AMR system of claim 1, wherein the RF communications are non-return to zero encoded.

4. The AMR system of Claim 1, wherein the RF communications are binary encoded.

5. The AMR system of claim 1, wherein upon detection of an RF inbound signal the squelch circuit arrangement of the meter interface module is adapted to initialized a device timer of the at least one endpoint device and start a communication capture and compare sequence in the at least one endpoint device, the squelch circuit arrangement further adapted to filter inbound signals until a valid communication is detected, wherein a valid communication comprises an inbound signal having a data rate that matches target data rate, and wherein the squelch circuit arrangement is further adapted to decode and process the valid communication for communication data.

6. The AMR system of claim 5, wherein a filtering arrangement of the squelch circuit arrangement is adapted to filter inbound communications upon detecting a base edge and a second edge so as to identify the second edge as a good edge or a bad edge as a function of a time of the edge, such that if the second edge is a good edge, a good count register of the filter arrangement is incremented, and if the second edge is a bad edge, a bad count register of the filter arrangement is incremented and the good count register is cleared; and clearing the good count register; and wherein the filter arrangement is adapted to detect and identify subsequent edges as good edges or bad edges until the target data rate is detected,

7. The AMR system of claim 6, wherein the squelch circuit arrangement is further adapted to perform a selectivity test after the second edge and subsequent edges are detected, wherein the selectivity test includes analysis of a time between the base edge and the second edge, a review of the bad count register and a review of the good count register to determine if the bad count register is below a predetermined limit.

8. The AMR system of claim 1, wherein the meter interface module of the endpoint device is adapted to include an extraction circuit adapted to receive and quantize as incoming data signal;
and an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector circuit includes a first counter to track a number of good edges and a second counter to track a number of bad edges;
wherein the extraction circuit is adapted to pass a recovered clock signal and a recovered data signal to the edge detector circuit when the first counter reaches a first predetermined value, and wherein the extraction circuit is adapted to reject the incoming data signal when the second counter reaches a second predetermined value.

9. The AMR system of claim 8, further comprising a divider circuit adapted to derive a plurality of clock frequencies and pass at least one frequency to the retraction circuit and to the edge detector circuit.

10. A method for communicating with at least one endpoint device in an automatic meter reading (AMR) system, wherein the at least one endpoint device includes a meter device and a meter interface module adapted for radio frequency (RF) communications, the method comprising the steps of:
initializing a device time of a digital squelch circuit arrangement of the motor interface module at least one endpoint device, wherein the squelch circuit arrangement is configured to respond to a target data rate;
starting a communication capture and compare sequence in the squelch circuit arrangement of the at least one endpoint device;
filtering inbound RF communication signals at the at least one endpoint device until a valid communication is detected, wherein a valid communication comprises the inbound RF
communication signal with a data rate that matches the target data rate;
decoding the valid communication for communication data: and processing the communication data.

11. The method of claim 10, wherein the step of filtering incoming communications further comprises:
detecting a base edge;
detecting a second edge and identifying the second edge as a good edge or a bad edge based upon a time of the edge, if the second edge is a good edge, incrementing a good count register, if the second edge is a bad edge, incrementing a bad count register; and detecting and identifying subsequent edges as good edges or bad edges until the target data rate is detected, until determining the target data rate is not present, or until a predetermined acquisition timeout is reached.

12. ~The method of claim 11, further comprising the step of:
performing a selectivity test after the second edge and subsequent edges are detected, wherein the selectivity test includes:
analyzing a time between the base edge and the second edge:
reviewing the bad count register; and reviewing the good count register if the bad count register is below a predetermined limit.

13. ~The method of claim 10, wherein the step of starting a communication capture and compare sequence includes detecting and receiving inbound RF communications.

14.~The method of claim 13, wherein the inbound RF communications are Manchester-encoded and the target data rate comprises a specific Manchester on-air data rate.

15.~The method of claim 13, wherein the inbound RF communications are non-return to zero encoded.

16.~The method of claim 13, wherein the inbound RF communications are binary encoded.

17. An endpoint meter device for use in an automatic meter reading system, wherein the endpoint meter device includes a meter interface module adapted to filter inbound radio frequency (RF) communication signals received from a meter reading device, the endpoint meter device comprising:
an extraction circuit adapted to receive and quantize an incoming data signal;
and an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector includes a first counter to track a number of good edges and a second counter to track a number of bad edges;
wherein the extraction circuit is adapted to pass a recovered clock signal and a recovered data signal to the edge detector circuit when the first counter reaches a first predetermined value, and wherein the extraction circuit is adapted to reject the incoming data signal when the second counter reaches a second predetermined value.

18. The device of claim 17, wherein the inbound data signal comprises a wireless radio frequency (RF) communication.

19. The device of claim 18, wherein the RF communication is Manchester-encoded.

20. The device of claim 18, wherein the RF communication is non-return to zero encoded.

21. The device of claim 18, wherein the RF communication is binary encoded.

22. The device of claim 17, further comprising a divider circuit adapted to derive a plurality of clock frequencies and pass at least one frequency to the extraction circuit and to the edge detector circuit.

23. A digital squelch circuit arrangement adapted for use with a meter interface module of an automatic meter reading (AMR) system, the squelch circuit arrangement comprising:
means for detecting an inbound radio frequency (RF) data signal having a data rate, wherein the data rate is represented by a series of edges and wherein the squelch circuit arrangement is adapted to be responsive to a target data rate;
means for detecting edges within the inbound RF data signal;
means for determining the data rate of the inbound data signal as a function of the detected edges and determining if the data rate of the inbound data signal matches the target data rate of the squelch circuit arrangement; and means for processing the data within the data signal if the data rate matches the target data rate.

24. The endpoint device mater interface module of claim 23, wherein said inbound data signal detection means includes an extraction circuit, and wherein said means for detecting edges within the inbound data signal comprises a digital squelch circuit arrangement that includes an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector circuit includes a first counter to track a number of good edges and a second counter to track a number of bad edges.