[Photo] Basic knowledge and question and answer of satellite TV

Question: I want to install a set of satellite receiving equipment, but I do n’t know what I need?
Answer: A set of satellite receiving equipment is composed of a receiver, a dish antenna (commonly known as a pot), a high-frequency head and a coaxial cable connection.

Q: Are the satellite receivers the same?
Answer: Satellite receivers can be divided into analog and digital types according to the type of received signals. At present, they are basically digital receivers; they can be divided into free receivers and conditional receivers (commonly known as card machines) according to the payment of received programs. Conditional receivers can be divided into several categories according to their different program encryption methods, such as single-system card machine or dual-system card machine, VIACCESS card machine or IRDETO card machine, etc.

Q: How is the free receiver different from the card machine?
Answer: This is very simple, the card machine has at least one slot that can be inserted into the card. In addition, free receivers are generally sold in the home appliance market, and few card readers are sold publicly.

Q: Does the bigger the pot, the more programs are received?
Answer: As far as the same type of pot is concerned, this is not wrong. But the number of programs is determined by the satellite you receive. In the case of a small pot, some programs with weak signals may not be received. If all the programs have been steadily watched, no matter how big the pot is, it will be a waste.

Q: What is the difference between C tuner and KU tuner?

Answer: The C high-frequency head is large and has a feed tray. It is used to receive C-band programs with a positive feed antenna. The KU high-frequency head is small. Most of them are integrated feed sources. The offset feed antenna is used to receive KU band. program.

Q: What do the big pots mean?
Answer: The cauldron refers to the positive feed antenna, which is used to receive C-band programs. The antenna diameter is usually more than 1.5 meters. The small pot refers to the offset feed antenna used to receive KU band programs. The antenna diameter is generally more than 0.45 meters.

Q: I want to watch the RTHK program. How do I configure it? Receive that star?
Answer: If you use a free phone, you can configure a 1.5-meter positive feed antenna, use two C-band high-frequency heads, one pot and two stars to watch 100.5 and 105.5 degrees two stars, there are some Hong Kong and Macao programs. If you use a small antenna, configure the card machine and watch 76.5 degrees stars or 113 degrees stars.

Q: I do n’t have a cable line at home. How can I use satellites to watch domestic programs?
Answer: If conditions permit, install a 1.5-meter positive feed antenna and use the free machine to watch programs on 100.5, 105.5 or 134-degree stars. For indoor reception, an antenna with an offset of more than 60 centimeters, equipped with an Aideid card machine, is rated at 110.5 degrees.

Q: I just came back from abroad, and I want to watch foreign programs, what equipment do I need to buy?
Answer: You can buy a dedicated receiver, use a 60-centimeter offset antenna to watch 146-degree stars, and there are dozens of English programs on it.

Question: After reading your article introduction, I also just installed BASE3000, received 76.5 stars, after aligning the stars, joined, the machine automatically received more than 70 channels, the satellite name downlink frequency symbol rate horizontal and vertical are defult default Value, although it is very convenient to use, but there is a problem I can't solve: How to manually add new satellites and transponders? In order to receive the programs that I want to watch but not in the default value of defult?

Answer: It is on the manual. In the general settings, determine the local oscillator frequency of the tuner 1-4 (basically enough), remember to correspond to the four-to-one switch position. The satellite setting is useless. The satellite is determined by the antenna, that is, the high-frequency head. In the settings of the transponder, choose to join, and in turn determine the antenna that the transponder uses, that is, the high-frequency head, downlink frequency, symbol rate and other parameters, and then exit to start scanning the program. Grab it slowly, otherwise you won't improve quickly.

Question: How does the receiver inform when the dual local oscillator uses high vibration and when to use low vibration? When I input 11131V26667, will the receiver automatically select 9.75?
Answer: The dual local oscillator tuner works according to the settings of your receiver. When the 22K switch is set to on, the receiver outputs a 22K pulse signal, and the tuner operates at a high local oscillator frequency. If you are watching a 113-degree star, use a low LO frequency, and set the 22K switch to off. When the 22K switch is used on both antennas, the low LO of the dual LO should be connected to the interface OFF, and the high LO of the dual LO must be connected to the interface ON.

Q: What programs are available for 76.5 and 88-degree stars?
Answer: The answer to this question is more troublesome. You can go to the following webpage to check that most satellite programs over Asia are available.

http://8515.cn/cd.asp

Q: How long can D cards on the market see?
Answer: I also want to know this question, there is no answer. If you really want to know, then ask the satellite broadcaster to see when they change the system.

Q: What is the pumpkin, Visa, and Aide system?

Answer: These systems refer to the encryption system used for satellite TV programs. There are 146, 75 and other satellites using the Nagra system, as well as some programs that have recently appeared on 76.5. There are 76.5 and 113 satellite programs using the VIACCSS system, and 110.5 satellite programs using the IRDETO system.

At present, the main conditional access systems in the world are VIACCSS system of French telecommunications company, MEDIAGUARD system of Canal Plus company, IRDETO system of Irdeto company, NEWSDATACOM system of News DataCom company and CRYOTOWORKS system of Philips company, POWERKEY system of American Scientific Atlanta Company , And NDS system and Nagra system, etc. There are also several high-tech companies in China that are conducting research and development. Among them, BTS is the only company that has successfully developed and has practical systems.

Q: I often see 410, 420, 430 on the Internet, what machines are they?

Answer: Hangke 410 is a domestically produced pumpkin system receiver. There are two system chip locations and two card sockets on the main board of the machine. Usually one is used to watch the 146-degree program. Since the system can be changed arbitrarily through the software, a deck is often added to change to the V + I dual system to watch 110.5 and 76.5 star programs, which is very welcome. 420 is based on 410, plus a system chip and a deck, and has two systems at the same time, through the switch or remote control to change the system status, ratings 146, 110.5 and 76.5 stars. Due to the difference in 110.5 decks, a switch is needed to watch. The 430 machine was produced in order to improve the defect of the 420 switch that needs to be toggled when watching, adding a card holder for the I system, and the system conversion is controlled by the remote control.

Q: Why do some 420s do not need to change the rear switch when watching 110.5?
Answer: Because both nagra and irdeto software use the same deck, but the clock of the nagra card is 4.5M, and the irdeto is 6M or 12M, so when n and I are switched, the back switch should be changed. Some cards have changed the relevant content in the program, so no need to change the switch. It is said that the program of the irdeto card can be changed to change the communication baud from 9600 to 12800.
Q: How to set the 0 / 22k switch when receiving 146 and 76.5 stars with 420?
Answer: Use 420 to receive 146 and 76.5 to use two systems, which can be set separately. First enter a system, select two input TONE BURST in the antenna setting, and set the local oscillator to dual local oscillator, and input the same local oscillator number of the high frequency head. Then set up in another system according to the above method, you can receive the corresponding program when switching the system. With this method, the connection between the two antennas and the 22K switch is not limited, and the interface can be selected at will.
Question: The 420 machine suddenly cannot receive encrypted programs, but only free programs. Why?
Answer: Please check if there is any problem with the card or card slot. In addition, did you select the type of program list by mistake, click the right button of the remote control to see if you can change it back.
Q: How to set up 420 antenna when receiving more than four stars?
Answer: The antenna is set to four in and one out mode, and the high-frequency head is set to double local oscillator. When setting the dual local oscillator parameters, enter the local oscillator parameters of the two high-frequency heads. The local oscillators of the two high-frequency heads are the same, as if it is 11300, and enter a parameter that is slightly larger than the local oscillator, such as 12300. Connect the four-in, one-out entrance to a 22K switch, the high-frequency high-frequency head to the 22K ON interface, and the low-frequency high-frequency head to the OFF interface. Two satellites can be connected to each entrance. When the satellite is scanned, it is searched according to the conventional method. When the local oscillator is set to be different from the basic oscillator, the frequency band is used for scanning, but the frequency of the sweep is not consistent with the actual frequency.
Question: What is the reason why the 420 machine sometimes crashes?
Answer: The power quality inside the machine is unstable, you can install a computer fan in the machine to cool the heat sink.
Q: What should I do if the remote control of the 420 machine does not work?
Answer: Open the remote control housing and change the EC pole of the amplifier S8050 (ie E-> C, C-> E, the middle B pole is unchanged, it is best to parallel a 2 ohm resistor in R3.
Question: How to solve the problem of Masec in 420 and 110.5?
Answer: Modify the downlink frequency and symbol rate parameters set by the receiver up and down, such as changing the parameters to 12379 V 41520 or 12383 v 41528. You can also change the local oscillator of the high-frequency head, for example, set the high frequency of 11300 to 11301.

Q: Can one antenna be connected to two receivers?
Answer: Yes, you can use the dual local oscillator C-band tuner when receiving the C-band, otherwise the two machines can only receive programs with the same polarization. Satellite TV signals are divided into two modes: vertical plan and horizontal polarization, which are controlled by the receiver by changing the voltage. If the two receivers watch differently polarized programs, there will be conflicts and they cannot be watched normally. With the dual LO C head, different polarization modes can be controlled with different LOs. There are two ways to connect two receivers with one antenna; one is to use a power splitter to split the signal into two channels and send it to two machines; the other is to connect the second machine to the signal output port of the first machine .
Q: What do you mean by one pot and more stars?
Answer: It refers to the method of watching multiple satellite programs by installing several high-frequency heads on one antenna when the antenna is large or the longitudes of several satellites are similar. The most commonly used is the one-pot double star collection of 100.5-degree stars and 105.5-degree stars.
Question: What does it mean to have multiple stars?

Answer: It is similar to the answer to the previous question, but requires a smaller difference in longitude between satellites, usually only reaching one head and two stars, such as 75 and 76.5, 146 and 144.

Q: Can a card writer write a mobile phone card?

Answer: You can't directly write the mobile phone card provided by the telecommunications department, but you can write the corresponding software to the 84 and 877 cards to simulate the function of the mobile phone card.

Q: What is the ALLCAM system?

Answer: ALLCAM originally refers to multi-system modules, which can be compatible with multiple encryption systems at the same time. The ALLCAM system combines the functions of multiple system modules with the system software of the machine to achieve the purpose of watching multiple encryption systems simultaneously. At present, the ALLCAM system is mostly used in the XSAT4X0 series, and a single 877 card can be used to watch more than five encryption system programs.

Q: Can I upgrade automatically under the ALLCAM system?

Answer: Not currently.

Question: How to edit the 877 card file of the ALLCAM system?

Answer: commonly used EditPro3.3 software for editing.

Q: Why can't the ALLCAM system watch 88C programs?

Answer: Because 88C is currently V2 and pumpkin double encryption, when using the allcam system, it will call the default V2 to decrypt, so it can not be watched. You can enter the 146 program first, return the system to the pumpkin system, and then watch the 88C program.

Question: Why is the signal of the 430 machine in the first 10 seconds very good, and there is a serious mosaic and sound interruption after 10 seconds?

Answer: Cannot use PAL output. In the receiver's output settings, change the image standard to automatic.

Q: What is a shared card?

Answer: An emulation card for sharing genuine passwords via the Internet. When watching satellite programs, you must connect to your computer and log in to the Internet, and then log in to the server that provides the password.

Question: How to replace 410 with a machine that receives cable digital programs?

Answer: Replace the high-frequency head with a high-frequency head for cable and replace the system software with 1_5_43_410-C.MFL. Note that some 410 tuner does not have a plug-in hole for wired tuner, which cannot be changed.

Introduction to Digital Satellite TV System

Digital satellite TV has developed rapidly in recent years, a form of broadcast television that uses geosynchronous satellites to transmit digitally encoded and compressed TV signals to users. There are two main ways. One is to transmit the digital TV signal to the front end of the cable TV, which is then converted into analog TV by the cable TV station and transmitted to the user's home. This form has been popularized and applied in various countries around the world for many years. Another way is to directly transfer the digital TV signal to the user's home: Direct to Home (DTH) mode. American Direct TV is the first satellite TV operating company to apply this technology. Compared with the first method, the DTH satellite has a high transmit power and can be received with a smaller antenna, which can be used by ordinary households. At the same time, it can directly provide user authorization and encryption management, develop digital TV, pay-per-view TV (PPV), high-definition TV and other types of advanced TV services, without being restricted by intermediate links. In addition, DTH mode can also carry out other digital information services in addition to many TV services, such as Internet high-speed download, interactive TV and so on.
There are two major international standards for DTH, the European standard DVB-S and the American standard DigiCipher. However, the DVB standard has gradually been widely used in the world, and the Dish Network, a later US DTH company, has also adopted the DVB standard.
A typical DTH system consists of six parts:
1) Front-end system (Headend)
The front-end system is mainly composed of video and audio compression encoders and multiplexers. The main task of the front-end system is to digitally encode and compress the TV signal, and use statistical multiplexing technology to transmit more programs on the limited satellite transponder band. DTH compresses video and audio signals according to the MPEG-2 standard. Using dynamic statistical multiplexing technology, it can transmit up to 10 sets of TV programs on a 27MHz transponder.
2) Transmission and uplink system (Uplink)
Transmission and upstream systems include communication equipment and upstream equipment from the front end to the upstream station. There are two main transmission methods: intermediate frequency transmission and digital baseband transmission.
3) Satellite
The DTH system uses high-power direct broadcast satellites or communication satellites. Due to technical and cost reasons, some DTH systems use high-power communication satellites. DTH companies in the United States and Canada have adopted more suitable dedicated high-power direct broadcast satellites (DBS).
4) User management system (SMS)
The user management system is the heart of the DTH system and mainly completes the following functions:
A. Register and manage user data.
B. Purchase and package programs.
C. Formulate program billing standards and user fees.
D. Market forecasting and marketing.
The user management system is mainly composed of a database management system of user information and program information, and a Call Center that answers user questions and provides various customer services.
5) Conditional access system (CA)
The conditional access system has two main functions:
A. Encrypt the program data.
B. Authorize programs and users.
At present, the conditional access systems used by DTH systems in the world are mainly: NDS in the United States, Irdeto in Israel, Via Access in France, and Nagra Vision in Switzerland.
The US Direct TV Company and Canada ’s Star Choice Company using Direct TV technology use the NDS conditional access system; the US Dish Network (Echostar) Company and the Canada Bell ExpressVu Company using Echostar technology use the Nagra Vission Conditional Access System.
6) User receiving system (IRD)
The DTH user receiving system is composed of a small dish-shaped satellite receiving antenna (Dish), an integrated receiving decoder (IRD) and a smart card (Smart Card).
IRD is responsible for four main functions:
A. Decode the program data stream and output it to the TV.
B. Use the key in the smart card to decrypt.
C. Receive and process various user commands.
D. Download and run various application software.
The IRD in the DTH system is no longer a pure hardware device, it also includes an operating system and a large number of application software. The currently successful IRD operating system is Open TV. American Dish Network has begun to gradually upgrade the user's IRD to Open TV system.


What is a geostationary satellite

Geosynchronous satellites are artificial satellites that orbit the earth in a circular orbit above the equator at a height of 35,786 kilometers above the ground. Its angular velocity is the same as the angular velocity of the earth's rotation, the direction of the detour is the same, and it is relatively stationary with the earth.

What is the function of feed

The feed is also called ripple horn. There are two main functions: one is to collect the electromagnetic wave signal received by the antenna, convert it into a signal voltage, and supply it to the high frequency head. Instead, it polarizes the received electromagnetic waves.

What is the function of tuner

The high frequency head is also known as low noise downconverter (LBN). Its internal circuit includes a low-noise inverter and a down-converter to complete the low-noise amplification and frequency conversion functions. It not only amplifies the 4GHz signal output by the feed, and then reduces the frequency to the first intermediate frequency signal of 950-2150MHz.

Types of satellite antenna

Satellite antennas usually consist of a parabolic reflector, a feed and a high-frequency head placed at the focal point of the parabolic concave mirror. At present, the KU channel mostly adopts the integrated feed frequency tuner. According to the feed source and the relative position of the high-frequency head and the parabola, there are feed-forward type (also called center feed type), partial feed type and feed-back type. Feedforward and partial feed are mostly used for reception, and feedforward is used for transmission.

What kind of antenna is good

The gain of the satellite receiving antenna is one of the important parameters, and the gain is related to the antenna aperture. The larger the caliber, the higher the gain. The beam of the antenna is as thin as a line. The higher the accuracy and smoothness of the antenna, the better. The parabolic surface of a general antenna is plate-shaped and mesh-shaped. Obviously, the plate-shaped paraboloid has a higher gain than the mesh-shaped paraboloid, and the plate-shaped overall paraboloid has a higher gain than the split-lobed paraboloid.

What is IRD

IRD (Intergrated Receiver Decoder) refers to integrated decoding satellite receiver.

Comparison of digital IRD and analog IRD

Digital IRD has the following advantages over analog IRD:

1. The image received by the digital IRD is basically the same as the sender;

2. Completely eliminate image distortion caused by color interference, differential gain and differential phase distortion;

3. Long-distance digital transmission will not generate noise accumulation;

4. Facilitate processing, storage, multi-tasking and encryption processing;

5. Save spectrum resources.

If the digital IRD has shortcomings, the price is slightly higher than the analog IRD.

How to choose a digital satellite receiver

When choosing a digital satellite receiver, in addition to the usual factors such as technical indicators, appearance, quality, price and after-sales service, the following issues should be carefully considered:

(1) Only when the low threshold value is selected can satisfactory results be obtained under the conditions of weak signal and small-caliber antenna reception, double-star reception with one high-frequency head or multiple high-frequency heads with a pair of antenna reception.

(2) There is a PID code addition setting, and at least a PID code modification method can guarantee the successful viewing of PID code programs.

(3) Only those with DISEQC switch can guarantee the excellent performance in multi-satellite reception.

(4) Only those with complete interfaces, such as two AV outputs, S terminals, RS-232, etc., can adapt to different needs and lay the foundation for upgrading.

(5) Only when there are enough channels, such as more than 250 channels, can the audience be expanded.

(6) Choosing a card reading device is beneficial to search satellite positions in all directions and find satellite programs on different satellites.

What method to check the power off memory function of IRD

The power-off memory function of IRD is very important to users. The simple inspection method is: connect the IRD normally

When receiving the active screen of a certain channel program, turn off the power, and then turn it on again after ten minutes to see if it is still received on the tuned program channel. If it is, the IRD has a power-off memory function. The activity screen of the program is selected here to avoid misjudgment.

What method to check the polarization switching function of IRD

(1) Intuitive method: see if you can directly watch satellite programs with horizontal and vertical polarization.

(2) Three-meter measurement method: Use a three-meter to check whether the voltage supplied by the IRD to the LNB can be changed; the required change range: 12-20V. But as long as there is 14-18V switching, you can receive both horizontal and vertical polarized satellite programs.


What method is used to easily judge the demodulation threshold of IRD

When measurement conditions are not available, the comparison method can be used to determine the demodulation threshold of the IRD. the way is:

(1) Connect a detected IRD and a to-be-detected IRD to the power splitter under the same antenna, and tune them to the same set of satellite programs (with active picture and accompanying sound), and they are in normal working state .

(2) Slowly change the azimuth of the antenna (ie change C / N), observe two! Whether the picture solved by RD has a square effect (mosaic), whether the sound is distorted or interrupted, and comparing the error codes of the two IRDs can judge the quality of their demodulation thresholds.

How to calculate the focal length of satellite receiving antenna

The focal length of the satellite receiving antenna refers to the distance between the center of the parabolic antenna and the focal point where the parallel electromagnetic wave signal reflects and converges. Denote the focal length by F, and its calculation formula is:

F = R * R / 4H (m)

Where: R is the surface radius of the parabolic antenna (m), and H is the depth of the parabolic antenna (m).

For feed-forward parabolic antennas, the focal length is determined by three support rods fastened to the antenna and the corrugated groove feed. Use this formula to verify the pros and cons of the product and installation technology.

How to calculate the azimuth, elevation and polarization angle of the satellite receiving antenna

It is known that E0 is the longitude of the satellite ground station, N0 is the latitude of the satellite ground station, E1 is the longitude of the fixed-point orbit of the satellite, FW is the azimuth of the receiving antenna, YJ is the elevation angle of the receiving antenna, and JH is the polarization angle of the high-frequency head. then

FW ＝ tg-1 [{cos （E1-E0） × cos (N0) -0.15127} / SQR {1－ (cos (E1-E0) × cos (N0)) × (cos (E1-E0) × cos ( N0))}]

YJ = tg-1 {tg (E1-E0) / sin (N)}

JH = tg-1 {SIN (E1-E0) / tg (N0)}

If FW = 0, it means that the satellite is in the south-south direction; FW <0, it means that the satellite is in the south-east direction; FW> 0, it means that the satellite is in the south-west direction.

What is the reason for the clutter of the satellite program receiving satellite programs

The clutter of receiving satellite programs is large, the common reasons are:

(1) The receiving antenna is not aligned with the satellite, making the signal too weak. You should adjust left and right first to find the best image and the least cluttered position, and then move up and down to fix it at a position free of clutter.

(2) The frequency drift of the high-frequency head causes the offset of the intermediate frequency signal and the amount of amplification decreases. The local oscillator frequency should be adjusted to make the clutter disappear.

(3) In heavy rain, heavy snow and foggy weather, the signal (especially Ku band) is attenuated. It will return to normal after rain and snow.

In addition, if the aperture of the selected antenna is too small, weakening the received signal will also cause clutter. When purchasing, the power of the satellite transponder should be considered. If the power is small, a larger caliber should be used and appropriate margin should be left. Can also choose low-noise high-gain high-quality high-frequency head.

How to use noise to determine the cause of failure

When receiving analog satellite signals, if the image is received and there is a lot of noise, the cause of the fault can be judged according to the noise status. Specifically, that is: when the screen is full of black noise, it means that the receiver frequency is high, and it should be adjusted down; when the screen is full of white noise, it means that the receiver frequency is low, so it should be adjusted up; There are many black and white noises on the upper side, which may be caused by improper adjustment of the installation, focus, polarization, azimuth angle and elevation angle of the high-frequency head, or obstructions such as buildings and trees in the direction of the antenna, which should be solved.

What are the causes of LNB damage

LNB is an active electronic component that has been working in the open air for a long time. The causes of failures are chronic, such as rain corrosion, and instantaneous, such as lightning and surge (voltage and current) shocks.

Rainwater corrosion: LNBs exposed to the sun and rain for long periods of time, such as the poor sealing performance of the sealed box, are prone to seepage, resulting in poor contact until damage. So it cannot be disassembled casually, it is best to add a protective cover.

Lightning strike damage: This is a common phenomenon, especially in multi-thunder areas and in multi-thunder seasons, the lightning protection measures of the antenna feeder system must be done.

Surge voltage and current shock: In areas where the power supply voltage fluctuates greatly, when there is a problem with the quality and layout of the AC regulator and power supply line installed indoors, surge shock damage often occurs. This can be judged by measuring the forward and reverse resistance of the LNB output interface with a multimeter.

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