EAS systems operate from a simple principle regardless of the manufacturer or the specific type of technology used: a transmitter sends a signal at defined frequencies to a receiver. This creates a surveillance area, usually at a checkout aisle or an exit in the case of retail stores. Upon entering the area, a tag or label with special characteristics creates a disturbance, which is detected by the receiver. The exact means by which the tag or label disrupts the signal is a distinctive part of different EAS systems. For example, tags or labels may alter the signal by using a simple semi-conductor junction (the basic building block of an integrated circuit), a tuned circuit composed of an inductor and capacitor, soft magnetic strips or wires, or vibrating resonators.
By design the disturbed signal created by the tag and detected by the receiver is distinctive and not likely to be created by natural circumstances. The tag is the key element, for it must create a unique signal to avoid false alarms. The disturbance in the electronic environment caused by a tag or label creates an alarm condition that usually indicate someone is shoplifting or removing a protected item from the area.
The nature of the technology dictates how wide the exit/entrance aisle may be. Systems are available that cover from a narrow aisle up to a wide mall store opening. Similarly, the type of technology affects the ease of shielding (blocking or detuning the signal), the visibility and size of the tag, the rate of false alarms, the percentage of detection rate (pick rate), and cost.The physics of a particular EAS tag and resultant EAS technology determines which frequency range is used to create the surveillance area. EAS systems range from very low frequencies through the radio frequency range. Similarly, these different frequencies play a key role in establishing the features that affect operation.
Acousto-magnetic EAS systems use a transmitter to create a surveillance area where tags and labels are detected. The transmitter sends a radio frequency signal at a frequency of 58 kHz (thousands of cycles per second), but the frequency is sent in pulses. The transmit signal energizes a tag in the surveillance zone. When the transmit signal pulse ends, the tag responds, emitting a single frequency signal like a tuning fork.
The tag signal is at about the same frequency as the transmitter signal.While the transmitter is off between pulses, the tag signal is detected by a receiver. A microcomputer checks the tag signal detected by the receiver to ensure it is at the right frequency, occurs in time synchronized to the transmitter, at the proper level, and at the correct repetition rate. If the criteria is met, an alarm occurs.
In response to the changing magnetic field created by the transmitter, the magnetic field domain of the tag material abruptly "switches" as the field strength varies past a particular point, whether positive or negative, during each half of the transmit cycle. This abrupt change in the magnetic state of tag material generates a momentary signal that is rich in harmonics (multiples) of the fundamental frequency. Using electronic signal processing techniques, the system identifies that the harmonics are at the right frequencies and levels, and that they occur at the proper time in relation to the transmitter signal. If the criteria are met an alarm occurs.
The transmitter signal energizes the swept-rf tag or label, which is composed of a circuit containing a capacitor and an inductor or coil, both of which store electrical energy. When connected together in a loop, the components can pass energy back and forth or "resonate." The frequency at which the circuit resonates is controlled by matching the storage capacity of the coil and capacitor. The tag responds by emitting a signal that is detected by a receiver.In addition to the small tag signal, the receiver also responds to the much larger transmitter signal. By detecting a phase difference between these two signals, and other properties of the tag signal, the receiver recognizes the presence of a tag and generates an alarm.
Yes, the HA169 base station can run smoothly when linked to the internet via a 4G or 5G SIM-based router with wired LAN output. It also works well with wired connections converted from WiFi repeaters. The core requirement remains stable network connectivity; as long as consistent internet access is secured, the base station functions as intended without extra configuration adjustments.
