An electronic device being a remote observer (12, 310), comprising: a wireless network interface; a processor; memory having stored thereon instructions that when executed are configured to cause the processor to: receive, from a broadcasting device (18, 20) via the wireless network interface, a message with an ephemeral identifier, wherein the ephemeral identifier is a temporary identifier that replaces identifiable information about the broadcasting device (18, 20) in the message to conceal which device sent the message with an authorized resolution of the ephemeral identifier; determine whether the processor can resolve the ephemeral identifier locally to obtain information about the broadcasting device (18, 20); if the processor can resolve the ephemeral identifier locally, determine the information about the broadcasting device (18, 20); and if the processor cannot resolve the ephemeral identifier: send the message to a remote resolver, receive at least a portion of the information about the broadcasting device from the remote resolver; characterised in that: the instructions are further configured to cause the processor to: send a list of subscriptions to the remote resolver, wherein the list of subscriptions indicates a type of pertinent broadcasting device (18, 20) or broadcasts that the pertinent broadcasting device (18, 20) may broadcast; and send a location for the electronic device (12, 310), wherein sending the list of subscriptions and sending the location for the electronic device (12, 310) are performed to enable the remote resolver to generate a list of pertinent broadcasters (18, 20) based on location, build a list from the generated list using the subscription list, and compute an ephemeral identifier for an observation period and an observation area for each device (18, 20) in the built list, wherein the observation period indicates how long the remote observer will look for broadcasting devices (18, 20) and the observation area indicates a geographical area where the remote observer is predicted to receive messages from broadcasting devices (18, 20). a wireless network interface; a processor; memory having stored thereon instructions that when executed are configured to cause the processor to: receive, from a broadcasting device (18, 20) via the wireless network interface, a message with an ephemeral identifier, wherein the ephemeral identifier is a temporary identifier that replaces identifiable information about the broadcasting device (18, 20) in the message to conceal which device sent the message with an authorized resolution of the ephemeral identifier; determine whether the processor can resolve the ephemeral identifier locally to obtain information about the broadcasting device (18, 20); if the processor can resolve the ephemeral identifier locally, determine the information about the broadcasting device (18, 20); and if the processor cannot resolve the ephemeral identifier: send the message to a remote resolver, receive at least a portion of the information about the broadcasting device from the remote resolver; characterised in that: the instructions are further configured to cause the processor to: send a list of subscriptions to the remote resolver, wherein the list of subscriptions indicates a type of pertinent broadcasting device (18, 20) or broadcasts that the pertinent broadcasting device (18, 20) may broadcast; and send a location for the electronic device (12, 310), receive, from a broadcasting device (18, 20) via the wireless network interface, a message with an ephemeral identifier, wherein the ephemeral identifier is a temporary identifier that replaces identifiable information about the broadcasting device (18, 20) in the message to conceal which device sent the message with an authorized resolution of the ephemeral identifier; determine whether the processor can resolve the ephemeral identifier locally to obtain information about the broadcasting device (18, 20); if the processor can resolve the ephemeral identifier locally, determine the information about the broadcasting device (18, 20); and if the processor cannot resolve the ephemeral identifier: send the message to a remote resolver, receive at least a portion of the information about the broadcasting device from the remote resolver; characterised in that: the instructions are further configured to cause the processor to: send a list of subscriptions to the remote resolver, wherein the list of subscriptions indicates a type of pertinent broadcasting device (18, 20) or broadcasts that the pertinent broadcasting device (18, 20) may broadcast; and send a location for the electronic device (12, 310), the instructions are further configured to cause the processor to: send a list of subscriptions to the remote resolver, wherein the list of subscriptions indicates a type of pertinent broadcasting device (18, 20) or broadcasts that the pertinent broadcasting device (18, 20) may broadcast; and send a location for the electronic device (12, 310), wherein sending the list of subscriptions and sending the location for the electronic device (12, 310) are performed to enable the remote resolver to generate a list of pertinent broadcasters (18, 20) based on location, build a list from the generated list using the subscription list, and compute an ephemeral identifier for an observation period and an observation area for each device (18, 20) in the built list, wherein the observation period indicates how long the remote observer will look for broadcasting devices (18, 20) and the observation area indicates a geographical area where the remote observer is predicted to receive messages from broadcasting devices (18, 20).