Wake-up receiver operating at 433 MHz

Abstract

Sensor nodes often have to work for a long time with a single battery. A change of the power source is sometimes not possible or involves effort and costs. If the node needs to be accessible for communication at any point of time it must have a radio in permanent receive state. This depletes the battery in a few days. The contradiction between long lifetime and permanent accessibility can be solved by using a separate wake up receiver on the node. In this work we present a sensor node with included wake-up receiver working in the 433 MHz ISM band. Our solution consumes 2.81lA of current in sleep state while still maintaining a realtime behaviour. The low current consumption is achieved by modulating a 125 kHz wake-up signal on the 433 MHz carrier in the sender. In the receiving node a passive demodulation circuit extracts the wake-up signal and feeds it to an 125 kHz low frequency receiver IC. An additional 16 bit address coding is used for an selective wake-up of nodes.

An 868 MHz 7.5 µW wake-up receiver with −60 dBm sensitivity

“…(14). Nevertheless, these results are still better than Gamm et al (2014), Marinkovic andPopovici (2011), andMagno et al (2016). Characteristic WuRx parameters are summarized in Table 4.…”

“…In the real world, most applications require a practical balance of this trade-off in order to respond to the desired performance. Publications like Gamm et al (2014) and Hambeck et al (2011) considered coping with that challenge. The efforts can be seen in the introduced WuRxs with −53 and −71 dBm sensitivity levels and consuming 8.4 and 2.4 µW, respectively.…”

“…2 from Gamm et al (2014) mainly down-converts the RF signal from 868 MHz to 125 kHz using zero bias Schottky diodes, which are configured as an AC-DC rectifier.…”

“…Other efforts can be made to improve the noise quality. According to Gamm et al (2014), the decoder is able to decode a signal with a minimum input power of −52 dBm. It can be seen that AS3932 limits the overall WuRx sensitivity as it is directly connected to the detector.…”

“…The CC1101 supports a 64 byte transmission FIFO queue, enough to handle the transmission of the complete WuPt. Unlike Gamm et al (2014), the number of bytes of a WuPt exceeds the FIFO size because of the higher carrier frequency (125 kHz) and the use of Manchester encoding. A solution they adopted is by re-filling the FIFO queue each time it is saturated until the WuPt is completely transmitted.…”