Abstract: A system for radio-frequency imaging of a structural environment is disclosed, including radio devices configured to transmit radio signals and a radio imaging device configured to receive the radio signals transmitted by the radio devices. The radio signals received at some times are scattered, reflected, or attenuated by an object collocated with an active localization device. The radio signals received at other times are scattered, reflected, or attenuated by the object not collocated with the active localization device. The system can obtain an indication of a location of the active localization device and, based on the radio signals received at the times the object is collocated with the active localization device, generate a radio signature of the object associated with the location. The system can then compute a score indicative of a likelihood that the object is at the location when it is not collocated with the active localization device.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.

Abstract: A system for radio-frequency imaging of a structural environment is disclosed, including radio devices configured to transmit radio signals and a radio imaging device configured to receive the radio signals transmitted by the radio devices. The radio signals received at some times are scattered, reflected, or attenuated by an object collocated with an active localization device. The radio signals received at other times are scattered, reflected, or attenuated by the object not collocated with the active localization device. The system can obtain an indication of a location of the active localization device and, based on the radio signals received at the times the object is collocated with the active localization device, generate a radio signature of the object associated with the location. The system can then compute a score indicative of a likelihood that the object is at the location when it is not collocated with the active localization device.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.

Abstract: Users of a proximity-based messaging system may be added to one or more proximity-based messaging groups that include users of user devices within an active area for the proximity-based messaging group and/or users meeting other criteria for being added to the group. Proximity-based messaging groups may be associated with events, such as music festivals, concerts, sporting events, and other gatherings and events. The active area of a proximity-based messaging group may correspond to a location of an event, an area surrounding an event, an area within an event location, and the like.