This article talks about the basic hardware composition of live set top box.
We don't want to talk about what we see when we dismantle the machine, so we can only see a pile of capacitors and resistors. Here we want to pay attention to the main chip and some important peripherals.
1. Tuner is a high frequency. This is the source of all data, whether it's audio and video, or OC data broadcasting, or VOD data. Generally speaking, there is only one box. However, for some set-top boxes with special functions, there may be many, such as PVR (personal video record). You may need to have two tuners.
QAM, demodulator. Tuner is a sine wave after digital modulation, but it is only an analog signal. QAM Demodulation is needed to convert the analog signal into a digital signal, which can be processed by CPU. Different channel modulation methods have different QAM specifications. For example, the wired modulation method is 64QAM, the terrestrial modulation method is COFDM (orthogonal frequency division multiplexing based on coding), and the satellite signal modulation method is QPSK. But fortunately, the software level generally does not care about this.
3. Demux, demultiplexer. After QAM, we finally get TS data, TS various services, audio and video, graphic data carrier. In order to facilitate transmission, we encapsulate these things in TS, but when our terminal processes them, we need to separate them independently. At this time, demux needs to appear. Separate various multiplexing streams, pat, cat, AV, PMT, etc. as needed.
Descrambler, descrambler. Operators in order to protect their own interests, audio and video data (note that only the audio and video data is scrambled, the business table is not scrambled) are scrambled, we need the key to solve the clear stream, so that we can carry out the next step of decoding work, and then we can see the audio and video data. This DVB organization provides a general scrambling and descrambling algorithm, so the function of the descrambler is standard.
5. Decoder, decoder. First of all, for set-top boxes, there may be multiple peripherals. Some set-top boxes have the function of "picture in picture" (to put it bluntly, decoding two programs at the same time). At this time, two decoders need to work at the same time. The DVB organization uses mepg-2 as the encoder, but because of the performance problem of mepg-2, for many HD programs, it uses H264 encoding, which can save 40% bandwidth.
For the domestic digital TV standard, MPEG-2 coding is adopted. A frequency point can generally carry 6 channels of programs or 3 channels of HD. But I heard that there are more than ten programs on one frequency in India. Ha ha, how low is the code rate? I don't know how they put up with such poor picture quality.
At present, the General Administration of optics stipulates that STB must be equipped with AVS Decoder... This so-called "national standard".
6. Avout, this is the way to the final output, which may be HDMI, DVI, VGA, color difference component output. The specific support depends on the function of the set-top box, which needs a module to manage in the SOC.
7. CPU, ha ha, this is nonsense, but interestingly, arm has almost unified the mobile phone chip, but there are also various architectures on the set-top box, MIPs / arm / superh / x86
8. Cacard interface, smart card interface. This is the place where the decryption key is stored. It needs an interface to communicate with the CPU. This interface may be I2C, APB (advanced peripheral bus), or other buses.
9. The above is the interface of broadcast stream. Now set top boxes generally have two-way function, so eth network card is needed. Ethernet card is generally divided into two modules, MAC / PHY. The physical layer here and the physical layer in the seven layers of OSI are not the same concept. OSI refers to the requirements of transmission medium, such as category 5 cable, category 6 cable, coaxial cable, etc. PHY here refers to the digital modulation module.
Mac is mainly responsible for converting the data from the upper layer into the coding format of Ethernet.
PHY is mainly responsible for the digital signal modulation into analog, convenient transmission.
10. All of the above are related to the main business logic, but in fact, for a SOC, it is far more than these modules.
other:
Nandflash interface, USB interface, SATA hard disk interface, graphics acceleration card, 2D graphics acceleration, WiFi, Bluetooth, 3G, cam and so on. These modules may be part of SOC or peripheral expansion chip, mainly depending on how the chip manufacturer provides the case
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How far(long) the transmitter cover?
The transmission range depends on many factors. The true distance is based on the antenna installing height , antenna gain, using environment like building and other obstructions , sensitivity of the receiver, antenna of the receiver . Installing antenna more high and using in the countryside , the distance will much more far.
EXAMPLE 5W FM Transmitter use in the city and hometown:
I have a USA customer use 5W fm transmitter with GP antenna in his hometown ,and he test it with a car, it cover 10km(6.21mile).
I test the 5W fm transmitter with GP antenna in my hometown ,it cover about 2km(1.24mile).
I test the 5W fm transmitter with GP antenna in Guangzhou city ,it cover about only 300meter(984ft).
Below are the approximate range of different power FM Transmitters. ( The range is diameter )
0.1W ~ 5W FM Transmitter ：100M ~1KM
5W ~15W FM Ttransmitter : 1KM ~ 3KM
15W ~ 80W FM Transmitter : 3KM ~10KM
80W ~500W FM Transmitter : 10KM ~30KM
500W ~1000W FM Transmitter : 30KM ~ 50KM
1KW ~ 2KW FM Transmitter : 50KM ~100KM
2KW ~5KW FM Transmitter : 100KM ~150KM
5KW ~10KW FM Transmitter : 150KM ~200KM
How to contact us for the transmitter?
Call me +8618078869184 OR
Email me [email protected]
1.How far you want to cover in diameter ?
2.How tall of you tower ?
3.Where are you from ?
And we will give you more professional advice.
About Us
FMUSER.ORG is a system integration company focusing on RF wireless transmission / studio video audio equipment / streaming and data processing .We are providing everything from advice and consultancy through rack integration to installation, commissioning and training.
We offer FM Transmitter, Analog TV Transmitter, Digital TV transmitter, VHF UHF Transmitter, Antennas, Coaxial Cable Connectors, STL, On Air Processing, Broadcast Products for the Studio, RF Signal Monitoring, RDS Encoders, Audio Processors and Remote Site Control Units, IPTV Products, Video / Audio Encoder / Decoder, designed to meet the needs of both large international broadcast networks and small private stations alike.
Our solution has FM Radio Station / Analog TV Station / Digital TV Station / Audio Video Studio Equipment / Studio Transmitter Link / Transmitter Telemetry System / Hotel TV System / IPTV Live Broadcasting / Streaming Live Broadcast / Video Conference / CATV Broadcasting system.
We are using advanced technology products for all the systems, because we know the high reliability and high performance are so important for the system and solution . At the same time we also have to make sure our products system with a very reasonable price.
We have customers of public and commercial broadcasters, telecom operators and regulation authorities , and we also offer solution and products to many hundreds of smaller, local and community broadcasters .
FMUSER.ORG has been exporting more than 15 years and have clients all over the world. With 13 years experience in this field ,we have a professional team to solve customer's all kinds of problems. We dedicated in supplying the extremely reasonable pricing of professional products & services. Contact email : [email protected]
Our Factory
We have modernization of the factory . You are welcome to visit our factory when you come to China.
At present , there are already 1095 customers around the world visited our Guangzhou Tianhe office . If you come to China , you are welcome to visit us .
At Fair
This is our participation in 2012 Global Sources Hong Kong Electronics Fair . Customers from all over the world finally have a chance to get together.
Where is Fmuser ?
You can search this numbers " 23.127460034623816,113.33224654197693 " in google map , then you can find our fmuser office .
FMUSER Guangzhou office is in Tianhe District which is the center of the Canton . Very near to the Canton Fair , guangzhou railway station, xiaobei road and dashatou , only need 10 minutes if take TAXI . Welcome friends around the world to visit and negotiate .
Contact: Sky Blue
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English: We accept all payments , such as PayPal, Credit Card, Western Union, Alipay, Money Bookers, T/T, LC, DP, DA, OA, Payoneer, If you have any question , please contact me [email protected] or WhatsApp +8618078869184
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For Warranty .
Contact US--->>Return the item to us--->>Receive and send another replace .
Name: Liu xiaoxia
Address: 305Fang HuiLanGe HuangPuDaDaoXi 273Hao TianHeQu Guangzhou China.
ZIP:510620
Phone: +8618078869184
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