Patent ID: 8164425
Filing Date: 2012-04-24
Classification: G06K,H04B

Abstract:
1. An interrogator used in a system including a plurality of interrogators, the interrogator comprising: a selection unit configured to select a channel from a plurality of channels in the system; an interference level detection unit configured to detect an interference level of the channel selected by the selection unit; a notification unit configured to notify one or more other interrogators in the system of at least one piece of notification information that includes a reception unit configured to receive a piece of the notification information from any other one of the plurality of interrogators; a determination unit configured to determine whether the selected channel is usable on a basis of a communication unit configured to perform wireless communication with a tag using the selected channel when the selected channel is usable; a channel change unit configured to cause the selection unit to select another channel when the selected channel is not usable; and a memory configured to store operation mode information indicating one of a plurality of operation modes that include a first operation mode and a second operation mode, wherein when the communication unit starts the wireless communication with the tag using the selected channel, the notification unit generates a first or second piece of the notification information and notifies the one or more other interrogators of the generated first or second piece of the notification information, the first piece of the notification information includes information identifying the selected channel set as the channel identifying information, the first value set as the usage status information, and the interrogator identifying information, the second piece of the notification information includes the information identifying the selected channel set as the channel identifying information, the second value set as the usage status information, and the interrogator identifying information, the first value indicates that the interrogator identified by the interrogator identifying information occupies a channel identified by the channel identifying information continuously for a long time, the second value indicates that the interrogator identified by the interrogator identifying information temporarily uses a channel identified by the channel identifying information, the notification unit generates the first piece of the notification information if the operation mode information indicates the first operation mode when the communication unit starts the wireless communication with the tag using the selected channel, and the notification unit generates the second piece of the notification information if the operation mode information indicates the second operation mode when the communication unit starts the wireless communication with the tag using the selected channel.