Siemens Aktiengesellschaft

Siemens Schweiz Ag

August Kaelin

Bruno Wenger

Peter Gysel

Dani Lippuner

Giuseppe Marbach

Daniel Mueller

A scattered light smoke detector containing an optoelectronical assembly for measuring scatter signals detected below at least one forward scatter angle and at least one backscatter angle and evaluation electronics for determining an alarm value in accordance with the difference between the scatter signals. Smoke signals are produced from the scatter signals by means of a pre-processing step and a measured value is obtained from the smoke signals. The measured value is formed by a linear linking of the sum of the smoke signals to the difference between the smoke signals BW, FW or by establishing the value for the difference between the smoke signals. The linear linking is calculated according to the formula k(BW+FW)+k(BW&#x2212;FW), in which BW and FW are smoke signals and kand krepresent two constants that are influenced among others by an application factor that is dependent on the environmental conditions in the installation location of the detector.

Scattered light smoke detector

Send filter for an echo canceler. A circuit includes a send path carrying a send signal, a receiver path carrying a received signal, an adaptive filter, a compensator contained in the received path, a digital/analog converter, a transmission unit, and a transmission line attached to the transmission unit, wherein over the transmission line, at least the send signal, the received signal, the echo signal portions are transmitted, and the send and received path are additionally connected with the transmission unit and the send signal is transmitted to the adaptive filter for the estimation of the echo signal which is processed in the compensator for the production of the receiving signal, with the send signal being conveyed, on the send path, to digital/analog converter, which, with the symbol rate of the send signal, produces square pulses, which in turn are transformed, in the send filter, connected with the digital/analog converter, into pulse forms useable for transmission via the transmission line, with the send filter being so conceived that the digital/analog converter merely has a resolution of two bits, whereby non-identities, particularly non-linearities, are compensated with the aid of the adaptive filter, the latter including at least one FIR filter portion of the storage compensation type.

Send filter for an echo canceler

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Bonstetten, Switzerland

August Kaelin