Monitoring arrangements

A system for monitoring at least one person passing through an area, the system comprising:

• a plurality of zones arranged in an array across an entry point to the area, such that one or more people entering the area must pass through at least one of the plurality of zones;
• wherein there are no gaps in the plurality of zones across the entry point to the area wherein a person would not be detected when entering the area;
• a primary monitor configured to detect activity caused by movement of one or more people through a first zone of the area using an active sensor and to obtain first data relating to detected activity in the first zone;
• a first secondary monitor configured to detect activity caused by movement of one or more people through a second zone of the area using an active sensor and to obtain second data relating to detected activity in the second zone, wherein the first secondary monitor is in circuit communication with the primary monitor;
• and
• a receiver in communication with the only the primary monitor;
• wherein, after obtaining the second data, the first secondary monitor generates a second monitor signal that comprises the second data and sends the second monitor signal to the primary monitor;
• wherein the first secondary monitor has a single communication path to the primary monitor and wherein all communications from the first secondary monitor flow to the primary monitor;
• wherein the first secondary monitor does not communicate with the receiver;
• wherein the primary monitor is configured to receive the second monitor signal and generate a combined data packet that comprises the first data and the second data;
• wherein, after the primary monitor generates the combined data packet, the primary monitor sends a combined signal to the receiver, the combined signal including the combined data packet.