Recherche dans les collections de brevets nationales et internationales
Une partie du contenu de cette demande n'est pas disponible pour le moment.
Si cette situation persiste, contactez-nous auObservations et contact
1. (WO1993019439) LECTURE A DISTANCE D'UN COMPTEUR
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

1 A remote meter reading system, comprising an encoder for association with a meter and a portable reader, the encoder having power terminal means for connection with a source of electrical power in the reader and adapted when powered to derive a digital encoding of the meter reading for transmission to the reader, wherein the encoder comprises impedance switch means serving to vary the input impedance at the power terminal means in representation of the digital encoding to provide a voltage variation detectable at said power source.

2 A system according to Claim 1, wherein the encoder comprises a frequency reference controlling the timing of the impedance switch means .

3 A system according to Claim 1 or Claim 2 , wherein the reader generates a periodic power signal which is inductively coupled with the power terminals of the encoder, operation of said impedance switch means being asynchronous with the power signal.

4 A system according to Claim 3, wherein the minimum period of operation of said impedance switch means is greater than the period of the power signal.

5 A system according to Claim 1, wherein the switch means compri diode connected between the power terminal means and a data line, the diode being selectively reverse biassed in dependence upon the level of said data line.

6 A system according to Claim 1, wherein the portable reader fur comprises means for amplitude modulation of said power signal, said impedance switch means serving additionally to decode said
modulation.

7. A remote meter reading system, comprising an encoder for association with a meter and a reader, the encoder having power terminal means for connection with the reader and adapted when powered to derive a digital encoding of the meter reading for transmission to the reader, wherein the encoder comprises switch means serving intermittently to short the power terminal means in representation of the digital encoding; and wherein the reader comprises a power source adapted to generate a periodic power signal; and detector means for detecting an asynchronous voltage modulation in said power signal consequent, upon said intermittent shorting of the encoder power terminal means .

8. A system according to Claim 8, wherein said detector comprises means for filtering said periodic power signal.