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Compare Options infrared wireless remote control

 post:2015-07-30


  Traditional infrared hand-held remote control has two main limitations, first of all, they need clearance line of sight to the receiver hosts (TV, set-top boxes, etc.); second, they are one-way, control is the "send only" and Host control they can not send any feedback to the remote. However, some of the remote control system for use in a small number of high-end entertainment system has an optical transmitter and receiver, so that two-way communication, but the control limit suffering quietly from the first - they need a clear line of sight path to send and receive control and data .
    The latest low-power RF solution enables designers to cost-effectively build intelligent remote control is no longer needed to control the gap horizon television or other device, you can receive feedback or real-time information from the device. A typical high-end remote control would include a microcontroller for keypad / touch screen management for RF transmitter and receiver (or transceiver), a display, and a number of power management to maximize battery life (Fig. 1). To ensure a RF remote control does not interfere with nearby room and other units, controllers, and therefore should allow one of the communication channel frequency more than a dozen selected by the user, so there is more than one remote control can coexist, but not control other devices TV or set-top boxes.
    Q. Based on some simple RF remote control / OOK agreement has been employed garage door opener, remote keyless entry systems and other applications do not require large amounts of data to be transmitted (usually just a "handshake" to verify the transmission, and open or close signal). The carrier frequency can vary greatly, rising from just a two megahertz to 433 MHz some industrial, scientific and medical applications. In an ASK system, the receiving section can be divided into three basic blocks - the input bandpass filter and separated from the carrier frequency of the input spectrum envelope detector that extract the required information, and compares the extracted information into into digital form (Figure 2).
Maxim MAX9933
    In this receiver, MAX9933 RF power detector is used in, and the MAX9030 is used as a comparator. Receiving from the circuit to the RF signal is AC coupled to the input MAX9933, and the number of the input RF voltage transfer function of the circuit is very sensitive to very small signals. ASK receivers allow very low level signals easily distinguish one and zero. A single capacitor, CCLPF, mine detectors to determine the response bandwidth. With a 10-MHz carrier and a data rate of 40 kbit / s, CCLPF capacitance of 150 pF and the RC filter MAX9030 comparator consists of a 100-thousand resistor and a capacitor 12:22 uF's.
In the transmission side to transmit OOK is very simple implementation - designer only needs to send a carrier signal to the power amplifier sends a "1", or send no send a "0." The switch signal can be processed by a chip: If the MAX1472, the input digital data stream which used to modulate crystal-based PLL oscillator output. In ASK transmitter is basically due to the ASK OOK signal receiver can catch a "bad" OOK transmitter.
    Simple OOK / ASK circuit causes the transceiver and receiver solution very cheap to achieve. However, there is no communication standard around which system may be designed so that substantially every system vendors set their own frequencies and data interfaces. Thus, each system solution is "unique" in the control of a system is not designed for the control system obtained from another exchange.
    In the past few years, the realization of a Bluetooth or ZigBee-based wireless solutions, even the cost of the wireless interface based on the Z-wave wireless control to reduce the volume of use has increased. Cellular phone systems are widely used, tablets and PCs, as well as the recently announced Bluetooth low energy Bluetooth standard Bluetooth interface main candidates for remote control applications. Furthermore, the use of standard interfaces allows designers to implement, can be easily connected to the system "universal" common control.
    For people who do not want to design their own Bluetooth subsystem design, the series offers SPBT2532 wireless bridge between your device and any other Bluetooth device (Fig. 3) by STMicroelectronics modules. In the small-sized blue modules with different types of interfaces (almost UART, SPI, I²C) all packed in a 10 × 13 mm profile. The series includes four SPBT2532 purpose I / O lines, multiple serial interface options, four times the 12-bit analog - digital inputs and up to 2 M.

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Keywords:Remote control, smart home, smart remote control
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