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Barcodes

Barcode systems use lasers or cameras to read barcode labels. These systems have been around for many years and are less expensive, but, require line- of-sight access to barcode labels in order to be read. They can be time consuming as each label must be found and read. Barcodes are cheap and work well, but they require a human being to perform a scan using line-of-sight.

Figure 9.2

The handheld scanners used to read barcodes work well. One of the advantages of barcodes is you scan only one asset. RFID can scan many assets at one time.

RFID

RFID (radio frequency identification) uses radio frequency waves to sense tags within its read field. An RFID reader emits a signal, which can detect RFID tags that contain data. There are many types of RFID tags and readers, which create read fields of widely varying sizes. This can be just a few centimeters (nfc), to hundreds of feet (active RFID).

RFID is faster and easier for collecting a lot of data in an automated way. Prior to deploying an RFID system, it's suggested that a building owner check the radio frequency in the current environment for conflicts in common frequency ranges. RFID tags are simply radio transponders. They are a small integrated circuit or computer chip which has a very small radio antenna built in. In passive systems, the tag does not have its own power source—it absorbs energy from the system reader antenna that senses the tag. The tag has been programmed with its own unique identification. When the tag is excited and absorbs the radio waves of the reader antenna, the tag sends out its unique identification, which is picked up by the reader antenna. Passive tags are typically smaller, less expensive and have a shorter range. They may be used with low cost assets in retail or manufacturing environments.

In active systems, tags have their own power source (battery) and don't need to use the reader's antenna radio waves to power up and transmit their identity. Active tags have a greater range, can store larger amounts of data and are larger than passive tags.

Tags come in a variety of sizes and shapes to address a variety of uses. The tag can be paper thin to fit inside a book. They also can be directly mounted onto equipment with an adhesive. Tags can be embedded in wrist straps, attached by a pin to clothing, worn on a belt, and even made tamperproof.

QR (Quick Response Code)

QR codes are two dimensional barcodes. Scanning can mean sending a text message, receiving a hyperlink, dialing a telephone number, or sending a message to an email address. QR has two major benefits. First, QR can handle a lot of data (7,089 numeric characters, or 4,296 alphanumeric characters), and second it can be scanned with a smartphone.

Readers and Antennas

Readers have an antenna attached to them. Essentially the reader interfaces or sits between the wireless portion of the system (the antenna) and the headend or system management and administration server. The antenna attached to the reader sends radio signals out that activate tags. It listens for tags to send a response and once it does, reads the data transmitted by the tag and sends it to the reader. Readers can have multiple antennas attached to it. The reader can decipher the signal and send the data to the host server.

 
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