In 1982, a U.S. judge, inspired by Spider-Man comics, persuaded a company to develop an electronic anklet and surveillance system suitable for criminals. Due to the influence of human bones, the wrist cannot be used as tightly as traditional metal handcuffs, and it is easy to be detached in a loose environment. Therefore, the electronic monitors are all worn on the ankles, forming an electronic foot ring (ankle). monitor).
In 1983, the first order required parole violators to wear electronic ankle bracelet to monitor their daily behavior for a period of time.
So far, the United States has applied the telephone line-based remote monitoring technology to the monitoring of non-custodial criminals for the first time, and directly implanted the electronic monitoring mode of “house arrest” from the remote transmission monitoring technology of fixed telephones:
Electronic ankle bracelet: An electronic transmitter worn on the ankle of the criminal, and an electronic monitoring circuit is embedded in the foot ring, which has the function of cutting or removing the alarm;
Signal monitoring device: The signal monitoring device is installed on the telephone line of the monitored place (usually the criminal’s home). The central computer monitoring system of the judicial supervisory agency.
Central computer monitoring system. Its working mode is that the electronic foot ring can continuously send out signals, the signal strength of the signal monitoring device receiving the electronic foot ring determines the size of the signal receiving range, and the signal monitoring device in the criminal’s home must be kept within a certain receiving range. If it exceeds this range, the signal monitoring device receives the abnormal signal emitted by the electronic foot ring or cannot receive the signal emitted by the electronic foot ring, and transmits it to the central monitoring computer through the telephone line. Based on this, the staff of the central computer monitoring system can infer that the criminal has left the monitoring range and report the situation to law enforcement officers.
