Abstract: A wireless terminal includes a pressure sensor, a wireless circuit, and a case accommodating the pressure sensor and the wireless circuit in a waterproof manner, and is left inside a stomach of a livestock animal to measure pressure inside the stomach and wirelessly transmit acquired pressure data. The case includes a cylindrical case body and a lid member closing an opening of the case body. The lid member has a measurement hole extending between inside and outside of the lid member and a protection wall part located outside of the case body. The measurement hole has a pressure-receiving pressure measurement part inside for measurement of the pressure and is closed. The measurement hole includes a first linear part and a second linear part intersecting in T shape with the first linear part, and has distal ends open to an outer face of the protection wall part.

Abstract: A slave terminal includes: a data transmission unit that wirelessly transmits status data relating to a condition of a monitoring target to a monitoring apparatus in response to a transmission trigger at every fixed period; a reply check unit that determines whether or not an ACK signal was sent back from the monitoring apparatus in response to the status data that was transmitted; an adjustment value calculation unit that determines an adjustment period of a random length when there was no reply; a timing update unit that outputs a measurement start trigger after the adjustment period has elapsed when there was no reply, the timing update unit outputting the measurement start trigger without the adjustment period when there was a reply; and a trigger generation unit that outputs the transmission trigger after counting the fixed period in response to the measurement start trigger.

Abstract: A wireless terminal includes a pressure sensor, a wireless circuit, and a case accommodating the pressure sensor and the wireless circuit in a waterproof manner, and is left inside a stomach of a livestock animal to measure pressure inside the stomach and wirelessly transmit acquired pressure data. The case includes a cylindrical case body and a lid member closing an opening of the case body. The lid member has a measurement hole extending between inside and outside of the lid member and a protection wall part located outside of the case body. The measurement hole has a pressure-receiving pressure measurement part inside for measurement of the pressure and is closed. The measurement hole includes a first linear part and a second linear part intersecting in T shape with the first linear part, and has distal ends open to an outer face of the protection wall part.