Digital TV set-top box add-on devices, also known as set-top box companions, or digital TV companions, are also known as set-top box audio and video distributors.
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Its function is to expand a digital TV set-top box or other machines such as satellite receivers, DVD players, etc., can be viewed by multiple TV sets, can be remotely controlled remotely, suitable for a large family to watch digital TV set-top boxes in different rooms. The signal, instead of separately purchasing the set-top box auxiliary machine and paying the viewing fee separately (Editor notes that multiple TV sets can only watch the same channel together). Just like a set-top box installed in every room, on each TV, it is equally convenient to watch and operate in front of each TV. With the increasing popularity of set-top boxes, the use of set-top box add-on devices has become more widespread, which has given birth to a new product, a new type of industry.
The main principle of the digital TV set-top box attachment device is that the first is to enable remote control of the set-top box remotely, and the second is to transmit the audio and video signals output by the set-top box to the television or monitor of each room by wire or wirelessly.
There are three types of structure: the first type is full-wire type. As shown in Figure 1, the infrared remote control signal and the RF signal output by the set-top box are transmitted to other TV sets through closed-circuit television lines. Each terminal has an infrared. Receive header.
The second type is similar to the first type, but the infrared remote control part realizes wireless remote control through a dedicated wireless transceiver conversion module, and then converts the audio and video output signals of the set top box into radio frequency signals, and the signal is transmitted to each room through the distributor. On the TV, just like the original CATV cable transmission. Since the infrared receiver repeater is independent, the expansion is very convenient. The third type is shown in Figure 2. The remote control mode is the same as the second type. It is wireless, and the audio and video signals output by the set-top box are wirelessly forwarded by low power. Generally, the 2.4GHz high frequency band is used to receive and demodulate audio and video signals for each room. The TV is watched in the AV state, and has 4 channels of frequency band for users to choose, so as to avoid the interference of the same band machine working at the same time, the audio design also meets the current consumption level, and is broadband and low-noise stereo. This way of receiving and expanding is more convenient, but the cost is higher. For example, Malata and Shinco recently launched mobile DVDs to enable wireless viewing of cable TV. The above three methods are all using the remote control of the original set-top box, which can wirelessly control the set-top box in different rooms, and can also add a universal set-top box remote controller to each TV set, which is suitable for promotion in ordinary families.
Here is a DIY set-top box attachment that is suitable for the majority of electronic enthusiasts. It is characterized by low cost and easy installation and use. Thanks to the modularity, the infrared receive and forward and audio and video conversion parts are already installed, and there is a stylish appearance. What electronic enthusiasts need to do is to disassemble the remote control of the original set-top box and weld three lines as required. Therefore, people who know a little about electronic technology can modify it, and can remotely transmit remote signals and signals without debugging. . The block diagram of the working principle of the complete circuit is shown in Figure 3.
The whole set of DIY set-top box attachments consists of two parts: the remote control transmitting part A and the set-top box adding device receiving the conversion part B: the remote part transmitting part A, mainly adding a wireless transmitting module Tx-3 inside the original set-top box remote control, The shape is shown in Figure 4. The external size is 18mmXl8mmx8mm. It has a transmitting antenna and three leads. Its function is to transmit the commands from the remote control not only through the original infrared medium, but also through the TX-3 module. The infrared remote control mode of the original remote control has been changed, and the remote control distance has been increased. The indoor wall can be remotely controlled by a wall, and the distance is up to 50 meters, which is enough to realize remote control of the set top box anywhere in a 100 square meter home. When modifying, the three leads of the Tx-3 module are connected to the positive pole of the remote control battery according to the red line, the blue line is connected to the negative pole of the battery, and the yellow line (which is the data input end) is directly connected to the infrared light-emitting tube inside the remote control to push the base of the triode. Or the output pin of the remote control integrated circuit (such as the 7th pin of the AS6122 integrated circuit in the PBX-1000 series digital set-top box remote control). Because the size of the T×3 module is small, it is easy to install it in the remote control. As long as the wiring is correct, the module is installed, the transmitting antenna is led out, and the wireless remote control is modified. If you do not want to use the original remote control of the set-top box for modification, you can also purchase the universal set-top box remote control for modification. Only before the modification, you must first adjust the remote control to the remote control of your own set-top box, and then use the launch module to press the above. The method was modified.
The matching set top box receiving device receiving conversion part B is composed of a data receiving infrared forwarding module IR-RX, an audio and video conversion radio frequency box RF-H radio frequency amplifying circuit and a power converter, and a 7805 voltage stabilizing circuit. The data receiving infrared forwarding module lR-RX restores the received remote control wireless signal into an infrared remote control signal to control the set top box, which already includes a receiver corresponding to the transmitting part, an infrared modulator, an infrared light emitting tube and a driving circuit, and is stable. Pressure circuit, etc., its appearance size is 65mm × 18mmx5.5mm. The use voltage is 7 ~ 9V, the appearance is shown in Figure 5. The audio-video conversion radio frequency box RF-H converts the AV audio and video signals output by the set-top box into the H or U frequency band of the TV. The working voltage is 5V, and the power converter outputs the power to the 7805 voltage-stabilized integrated circuit. The device adds an amplifying circuit to the output, which can be combined with a conventional CATv cable TV distributor and transmitted to multiple TV sets for reception. Closed transmission ensures image clarity.
When in use, the set-top box attachment device receives the conversion part and the whole machine is placed above the machine box, and the infrared emission part is aligned with the infrared receiving window of the set-top box, as shown in FIG. 6, the control signal sent by the wireless remote controller can be received, and the set-top box is received. Realize remote control and viewing. If there are many rooms, sometimes you have to watch the show in the guest-hall, sometimes you have to watch the show in the bedroom or study. If a remote control is not convenient, just give each TV a modified remote control. It is more convenient to use. In addition, the universal set-top box/television remote control is newly developed. It can be matched with set-top boxes that are not unified in all regions of the country, and can also remotely control the power switch, volume and AV status of all TV sets. This way all viewing functions can be implemented on a remote control. As mentioned at the beginning of this article: the set-top box seems to have been installed in every room, and every TV set will feel the same convenience in front of each TV.
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