D.V. Fedotov

This article describes short-range (several meters) high-resolution (several centimeters) location devices. These devices have many applications over the entire world. Generally, such kind of devices uses active or passive infrared location or microwave technology. However, since 2002 year ultra-wide band (UWB) devices extremely quick go to market because Federal Communication Commission officially adopted UWB radiofrequency (RF) rules. Problems of current devices depend of technology type. For example, radars, which use ultrasound technology, can be simple blocked by piece of paper or clothes. Infrared or laser sensors have high precision but can operate only in indoor conditions. Reducing of precision of such kind of sensors caused by air with different temperatures, which is present in working area. Microwave devices have high current consumption and cost. High cost caused by cost of microwave components and for more high frequency components have more cost. Additionally no one technology has possibility of distance measurement till object and its size (small animal, child, adult) or make it bad like pulsed microwave sensors. Current UWB radars have better performances but they are still expensive and have high power consumption. Offered UWB devices solve many of mentioned above problems. In this structure power control of all circuit is implemented. Power is controlled by digital circuit, which is used time gating. Digital circuit also produces short transmitting pulse (several nanoseconds) and receiver-s window gate (also several nanoseconds). Additionally circuit consists high-speed automatic gain control of receiver-s low noise amplifier. High-speed automatic gain control operates in real time. This allows producing correct processing of amplitudes of reflected signals, which goes from close ranges. Proposed circuit makes location device powerful, compact and cheap especially when the devices uses patented compact UWB antenna. Other advantage of offered circuit is its universality. The circuit may be used as radio-frequency front end for many UWB devices without structure changing. Among these devices are following - short-range radars, radar sensors, rangefinders for home and office security, RF identification devices, level meters, through wall imaging systems, local positioning systems etc. Especially the circuit need to be applied for purposes where low cost is critical for mass production applications. Using the same RF circuit and digital processing circuit all mentioned above devices have only different processing algorithm which is not considered in this article.