The Buddy System can be used for a variety of different functions, from monitoring the environment to recording movement. Each module has two modes of operation, its default and the “Buddy” mode. The default mode allows for the sensors and the sensor network to gather data. In the Buddy mode the information that is being collected is transmitted over the RF link to the companion unit which in turn creates and displays an interface to indicate to the user that data has been collected. The units are able to self configure once configured. Depending on the application for the user, the communication range between the sensor units may vary. In some cases, the units can operate as stand-alone, without the need of a hub. The unit can be battery operated and operates in a wide variety of temperature, moisture and shock/vibration ranges. The units can be secured and stored in packages or housings. Each unit has a unique I.D that can be read by a reader when in proximity. Each unit can be attached to its own data service link, which in turn can be attached to a home location network (HAN) through either wireless or wired connections. Each sensor unit has internal memory for use when there is no data service link. The sensor system is available to commercial customers. The system is modular and expandable. New components can be added to the system using an expansion board that can be attached to the system. The expansion board can also provide other functions such as serial communication to interface with a laptop or the internet. The modularity of the system allows additional functions and sensors to be added as needed, making the system very flexible. Multiple sensor units can be connected to a single base station through wireless connection. The system has internal battery backup so the system is always ready for use. The battery backup is rechargeable through the AC/DC power adapter that also acts as the charging unit for the system. The sensor system uses a sensor network technology to collect data from various components for either a single user or multiple users. The network is able to provide data on any component or environmental parameters. The sensor network technology has a standard communication protocol which enables the sensor units to be connected in different ways to create sensor networks and allow communications between sensor units. Various sensor units can be integrated with a single hub using the same communication protocol. The sensor network protocols are based on various communications standards, such as Bluetooth and RF, and allow connection to other hardware devices such as phones, webcams and laptops through cables and wireless connections. The system will be able to connect to a sensor hub and other sensors or other devices as a part of its communication network. The module uses the Bluetooth protocol for data transmissions. The sensor units will automatically discover all other sensor units within the network and communicate to establish the network and then will transmit data. In some cases, the sensor hub may be part of the sensor network. It will be connected through one of the nodes in the network. The system uses Bluetooth Technology to monitor locations, such as rooms, rooms of a house, or the outside environment for multiple users, or to monitor and compare environmental data between multiple users. The system uses sensor technology to capture information about any parameter or environmental condition. Examples include air temperature, relative humidity, door position, location, time, and battery level. Additional sensors may include other environmental parameters, such as sound and motion. The sensor system is also able to collect video, audio and take still image data. In an exemplary embodiment, the sensor system is able to receive data from various sensors and input information from the communication network through the RF link. The sensor units will transmit any data, such as temperature, relative humidity and battery level. The sensor units will also be able to transmit a video or audio message. In some cases, the hub may be connected to other electronic devices such as a laptop or computer. Additional or alternative exemplary embodiments may include one or more of the following: 1) the sensor unit can be configured to store the data gathered and transfer it over the network. 2) the sensor unit can be configured to receive data transmitted by other sensor units. 3) the sensor unit can be configured to store and transmit data over a wireless link. 4) the hub can receive data from multiple sensor units at a single time or in a sequential manner, creating a distributed network. 5) the hub can transmit data to multiple sensor units at a single time or in a sequential manner, creating a distributed network. The system can also be configured to record and analyze the data collected by the sensor unit(s), monitor and compare the data across multiple users, view real time data over the wireless link, and send alerts to another user. The system allows users to upload data files from their home computer or laptop, create maps, or analyze data on their personal computer using a desktop application. The wireless network will be able to connect with mobile devices such as cell phones and PDAs. The system may be used as part of a personal safety system, a communication system, or as part of a building management system. The system includes the sensor unit, a communication unit and an attachment structure, such as a holder or belt, to support the unit. The communication unit may be an adaptor to connect to the sensor unit. The communication unit includes a processor, an RF communication unit for transmitting and receiving RF communications and a power source, such as a battery. The communication unit is able to receive data and send data over the communication link through the RF link. The sensor unit includes a processor and a memory and is able to transmit data and receive data over the RF link. The communication unit transmits and receives data through an antenna connected to the communication unit. The sensor unit can be located inside or outside the communication unit. An exemplary embodiment of a sensor unit can include the following elements: The sensor unit is able to monitor parameters, such as temperature, relative humidity, sound, relative motion and video. The data collected by the sensor unit is stored and transmitted to other units by a network or sensor hub. The sensor unit is able to transmit data to an attached device such as a camera or a laptop. The sensor unit is able to send a status and/or other data messages to an attached device using a wireless communication link, a cable or other communication link. The sensor unit is able to receive data from an attached device using the same communication link. The sensor unit is able to receive and display images from an attached device using the same or a different communication link. The sensor unit can collect images from an attached device using a wire, a cable, a wireless communication link, a wireless network or any combination of these methods. The sensor unit can upload images from an attached device to the server. The server is able to analyze the images collected, monitor and compare data from multiple users, create maps, and send alerts. The sensor unit may be an audio, video, still camera, a PDA, a cell phone, a camera phone or a computer. The sensor unit can be attached to a belt, a pocket, a shirt pocket or other garment. A sensor network may include several sensor units. The sensor units are connected to one another by a wireless communication link and an antenna to form a network. The sensor network allows a user to gather data without using wires or cables and allows the sensor units to be located remotely from the hub. The sensor units are able to communicate directly with each other through the wireless communication link and receive data from the hub through the communication link. The sensor units are able to share information, such as video, audio or text messages with other network users, either directly or through the hub. The hub is able to receive data from sensor units, from the sensor hub, and data from mobile devices. The hub includes one or more processors and a memory to store data received from the sensor unit, the sensor hub and from other units, such as computers. The hub also includes an antenna to receive and transmit data over the wireless communication link. A communication system includes a hub, a sensor network, and a host unit. The sensor network is able to collect data and store the data in the hub. The hub is able to analyze the data and send information from the sensor network to a host unit. In one embodiment, the sensor network includes a hub, which includes a memory and a processor. The memory stores data from the sensor network, and the processor is able to receive and transmit data through a wireless link. The hub is able to determine if data was received from any sensor units connected to the hub and monitor and/or compare data collected by the sensor network for a period of time, such as one hour, three hours or longer. The data collected by the sensor network is compared to predefined user specific data and is also compared to data collected from other sensor networks. The data collected can include sound or noise, motion, video, image, audio, a sensor reading from a computer or a computer program. The data collection by the hub may be performed for any period of time, such as one minute, five minutes, 10 minutes, 15 minutes or longer. The hub may transmit a signal to a display to display a message from the sensor network on the display. The hub may be used to monitor the internal or external environment and analyze the environment. The hub may receive and transmit data over a wireless link. The hub may store received data and transmit data over a wireless link. The hub can send data to other hubs over a wireless link or a wired link. The hub is able to perform data analysis and is able to transmit the results over the communication link. The hub may compare data between multiple units. The hub may be attached to