| Collection of multi-star receiving methods (1) |
| Date: 2006-7-8 19:09:11 Author: Source: |
| Before, direct broadcast satellite (DTH) in the sky more and more, there's Feng hundreds of dazzling television projects; constantly new satellite into space, stop the emergence of new channels; recipient of favorite channels and at different times The programs that I want to watch are often scattered on different satellites; in order to counter the decryption and D card, some channel service providers constantly update the encryption (scrambling) method, playing with the hackers "You are a foot tall, I am a taller" For the sake of commercial consideration, some channel service providers decrypt and broadcast some wonderful programs from time to time, and the receiver can keep up to date with the latest information in this regard through the Internet and change stars in time. Both the current receivers and receiving cards have 0 / 12V, 0 / 22kHz, 13 / 15V, DiSEqC and other switching functions, all have the ability to support multi-satellite reception-all of these have created an urgent need for multi-satellite reception, and star friends with multi-star reception capabilities can also Enjoy more fun than others. Naturally, in the antenna column of the forum, the hot topics that TVRO fans are concerned about are concentrated on multi-satellite reception. This article collects the published materials and pictures (the ownership belongs to the original author), combined with their own experience and experience, comprehensively introduces various methods of multi-satellite reception, and analyzes their respective advantages and disadvantages, as well as reference for the majority of satellite TV enthusiasts. Single-antenna changing satellite receiving method This is the method currently adopted by many TV enthusiasts due to limited conditions. When changing stars, first use the tool software, "Star Finder Calculation and Program" Satellite.exe, "Azimuth and Elevation Calculation Tool" of this site or the receiver itself. Function, etc., to calculate the azimuth, elevation and polarization angle of the received satellite. Then, loosen the fixing screws on the antenna, adjust each part, and then adjust the antenna patiently through the signal strength and signal-to-noise ratio indication of the loading and unloading machine, and then the receiving satellite can be replaced. In order to facilitate adjustment, preferably a television receiver and want to move to the vicinity of the antenna, in order to observe the effect of the antenna adjustment. Some Xingyou have some special equipment, such as small TVs, channel meters, etc., to avoid the trouble of moving the TV and the receiver If you often need to change between several satellites, you need to adjust the antenna to receive these satellites in advance, and then make a mark on the antenna bracket to change the stars faster. Some star friends have installed a protractor on the antenna. Staying on the scale of the satellite also helps to change the star more conveniently, Under normal circumstances, this method takes tens of minutes to change the star, for the unskilled, it takes more than half a day. If there is a sun shadow ruler (SolarSat technology) on the satellite, then the star change can be completed within a few minutes, but it can only be done during a specific time period during the day when there is sunlight. The advantage of this method is that the equipment is simple and the technical content to be mastered is low. Disadvantages are: inconvenient to change stars, time-consuming and laborious, antenna fixing parts are easy to damage, and signal quality is difficult to ensure. If the antenna is installed out of the reach, such as a rooftop installation, there may even be a personal safety hazard when adjusting the antenna. Multi-antenna reception The example and configuration of multi-pot reception given by Xingyou "Valley Satellite", this solution obviously requires large capital and space expenditure. For domestic receivers, it is an example of extreme fever. The general situation Next, most domestic star friends only use 2-3 antennas Using multi-pot reception, the installation of the antenna is similar to that of using a single pot. Since it does not need to be adjusted, the receiver antenna and LNB are optimized and adjusted once, and generally their posture is not changed. The key to multi-pot reception is the selection and use of the corresponding intermediate frequency signal switch for each antenna. There are two types of switch: manual switching and automatic switching. The manual changeover switch is usually restructured with a common switch, which is prone to signal attenuation and input impedance mismatch problems, which affects the reception quality and is more troublesome to use. Few people use it Through the 0 / 12V, 0 / 22kHz, 13 / 18V, DiSEqC and other functions provided by the satellite receiver, it is a better way to use a dedicated switch. These switches are generally available in the electronics market, with prices ranging from a few dozen yuan to hundreds of yuan. The three modes of 0 / 12V, 0 / 22kHz and 13 / 18V are mostly relay-type two-way switching type. The principle is equivalent to a single-pole double-throw switch, and each adopts different triggering methods. 0 / 12V depends on the presence or absence of the 12V voltage provided by the receiver to the switch to control the signal path selection of the relay. Because it is necessary to lead a power cord to the switch separately, the switch should not be too far from the machine, so most receivers now do not provide this function. The 0 / 22kHz switch is used to control the switching of the switch or the selection of the double local oscillator high frequency head local oscillator through the 22kHz pulse signal sent by the receiver. It can be used to trigger the relay (Editor's Note: This kind of switch is generally not selected for the relay type, but is selected. Electronic switch type. Even if the relay type is selected, a high-frequency head relay must also be selected, so as to ensure accurate switching and no misoperation). 13 / 18V Tianguan selects polarization through 13V and 18V voltages, and can also be used to trigger relays. In these several ways, the control signal is transmitted through the coaxial cable connected to the antenna, and there is no need to wire the switch separately. If there are dual local oscillators in the system, the 22kHz switch cannot be used to control the switching of the antenna. Similarly, if the system uses a dual-polarized single-output high-frequency head, the 13 / 18V switch cannot be used. In view of the limitations of the above three switches in use, as well as the mechanical life of the relay and the attenuation of the high frequency head, there has been a way to control four antennas at the same time, without additional power supply, and will not grab the control signal with the high frequency head relay life without shortcomings and like decay of the changeover switch - which is DiSEAqC. It was developed by Philips. The core of the switch is a single-chip microcomputer. The signal output from the receiver controls the four-sided antenna switching. The price is more expensive than the first three switches, but the performance is much better. The above switching can be used with the string, if the present system does not double the first vibration, by adding DiSEqC 0 / 22kHz can control the LNB 16, and the head does not affect the dual-polarized work. When using a four cut one switch and four 22kHz switches, each connector of the four cut one switch is connected to a 22kHz switch, each 22kHz The switch is connected to a C head and a Ku head. The Ku head is connected to the ON interface, and the C head is connected to the OFF interface. Such as 105.5C / 146Ku, 100.5C / 100.5Ku, 88C / 110.5Ku, 166C / 76.5Ku and so on. XSAT Take the 4 × 0 receiver as an example. In the antenna setting, select option 4 to input DiSEqC. The important thing is the setting of the local oscillator. Each antenna is set to dual local oscillator, the high frequency head input Ku head local oscillator such as 11300, low local oscillator input 9850. After setting, enter the program receiving menu, perform satellite search, select single frequency search as the search method, Ku band program, directly enter the parameter search. The downstream frequency of the C-band program needs to be changed. The frequency calculation method is; C's LNB LO frequency-actual frequency + set frequency. For a group of 3632, the input downlink frequency is 5150-3632 + 9850, that is, 15000-3632 = 11368. In the single frequency search, this group enters 11368, 26667, vertical, and you can search for the program. Other signals can be deduced by analogy. The actual frequency is obtained by subtracting the actual frequency from 15000 Specific examples (provided by "Satellite TV Era"); use a satellite digital TV receiver in combination with DiSEqC switch and 0 / 22kHz switch to flexibly switch domestic and foreign satellite digital TV programs received by 8 antennas. Equipment configuration: Antenna: 1.8m antenna 6 sides (respectively receive Asia Pacific No. 6 □ Xinnuo No. 1 □ Asia No. 2 □ Pan American No. 2 □ Pan American No. 8 □ Asian 3S C-band domestic meal satellite signal), 0.8 m Ku antenna 2 sides (Pan Am 2 and receiving Ku-band domestic and 2 the satellite signal Asia); LNB: 6 PBI Turbo-1200 C-band bipolar high-frequency heads, PBI GOLD-1040 Ku-band partial-feed bipolar high-frequency heads Switch: PBI MS -41D DiSEqC1.0 a four cut a switch (operating frequency 950-2200MHz, insertion loss less than 3dB, power 12-20V, 30mA), PBI MS-21P (0 / 22kHz switch) four Receiver: PBI DVB-1000H7 satellite digital TV receiver Switcher parameter setting; The advantage of multi-pot reception is that the antenna can be optimized and adjusted separately. It is ideal for cooperation with LNB, the quality of reception is highest, switching satellites is fast, and there is no sense of pause. It seems to be received on one star. It is suitable for the collective reception of large units such as communities, buildings, hotels and so on. Households on the top floor, households in villa buildings, and residents in suburban and rural areas may also consider adopting them. The disadvantages of multi-pot reception are large investment, high cost, strong professionalism, certain technical requirements for the configuration, large space occupation, not suitable for individuals to adopt in our cities, nor for separate reception of residential units in general residential units One-pot multi-star (multi-LNB) receiving method An example of one-pot multi-star made by domestic star friends, and one-pot multi-star example abroad. One-pot multi-star reception is a reception method invented by star friends using a single reflective surface to install multiple LNBs. Under normal circumstances, the ordinary "pot" (antenna reflection surface) has only one main focus, and only one LNB can be installed. There is a so-called "off-focus" position that deviates from the main focus. According to related calculations, the relatively high-gain region is not a point, but a comet-like shape, with a trailing area deflected by a relatively dense area of ​​reflected beam energy the apofocus, tailing longer, wider, while the lower the energy density of the "tail" of the signal. The signals collected in the trailing part of "off-focus" cannot be effectively used, so the received signal strength is lost and the reception efficiency is low. C + Ku composite LNB is required to receive C and Ku programs in the same pot with the same star. At present, such composite high-frequency heads are rare in the market, and often need to be self-made. The general approach is to saw the end of the C-band LNB feed, cut into a Ku LNB, and make a composite LNB head to receive C and Ku-band programs from a satellite. This method Belonging to one pot of multi-LNB reception, it can also be regarded as the scope of one pot of multi-star reception. One-pot multi-satellite reception uses a large antenna in the area deviating from the main focus, and can still collect the characteristics of signals with sufficient strength to meet the reception, to achieve the reception of one antenna reflection surface and multiple LNBs. The installation of a one-pot multi-satellite receiving antenna is similar to that of a single satellite receiver, but it requires more skill and patience. How to make the LNB receive the strong signal of the weak signal satellite as much as possible, how to make each LNB receive the signal in a balanced manner, and how to enable several LNBs to receive enough signals are all worthy of study. What kind of reflective surface is used to concentrate the signal on the near-strip area or multi-focus for multi-LNB reception is beneficial for multi-star reception, which is another issue worthy of study. Foreign pot of multi-satellite dedicated hyperbolic multifocal antenna (Triax MulTIFocus), there is no national coverage. The configuration of the one-pot multi-star feeder and the switch is the same as that of the multi-pot reception, and will not be described in detail. Points pot of multi-satellite installation are: 1. Design and manufacture the brackets for installing multiple LNBs. The brackets used for one pot and multiple stars should be slightly curved, or the lateral position can be adjusted to match the local synchronous satellite orbit ground design projection; when using a positive feed antenna The bracket should be stable, and at the same time, it should not be too large, so as not to block too many front signals. It is best to adjust and fix the LNB conveniently for repeated fine-tuning. 2. Choose a suitable antenna. As far as possible, use a deflection-feed antenna with a large reflection area and a long focal length as a reflection surface for multi-satellite reception. The large area can compensate for the partial loss of the received signal of "off-focus"; the long focal length helps to disperse the installation of multiple LNBs and avoid the LNB and the metal frame from blocking the incident signal. The bracket is also more difficult to design and make. 3. Select the satellite whose main antenna is in focus. Under normal circumstances, the main focus should be on the star with weaker signal, and the satellite with strong off-focus receiving signal should take care of the reception of each star as much as possible. 4. Determine the position of each LNB. Under normal circumstances, the position of each LNB should be oriented parallel to the geosynchronous orbit, and then the position of each LNB can be determined through repeated trials and adjustments. Before adjustment, calculate each position by an approximate formula The rough location of the LNB will help with the purposeful adjustment. Details of the calculation method; first find the azimuth and elevation angle of the receiving satellite; determine the main focus satellite, adjust the antenna according to the main focus satellite; then use the formula to calculate the approximate distance between the main focus and "off focus" L = D , L in the formula is the distance from the main focal point to the "off-focus", the unit is the same as the unit of the antenna focal length; F and Y are the azimuth and elevation angle values, and the subscripts z and p indicate the main focal point and "off-focus", respectively; Use the "off-focus" LNB with the main focus not the main axis, and take a fixed length with L. Look slowly along the arc on the pot surface to find the satellite signal. When Fz-Fp is greater than zero, the "off-focus" head is on the west side of the main focus , Otherwise the opposite; when Yz-Yp is greater than zero, the "bias" should be above the main focus, otherwise the opposite is true. During the solar equinoxes and autumnal equinoxes, you can also use the sun to directly determine the location of the LNB. You can refer to my article: "Thanks for the opportunity! --One of the topics of autumn equinox solar terms. 5. Hands on. In the practice of multi-star reception, it is very necessary to do it yourself. It is impossible to buy ready-made, eat ready-made meals, have someone else replace it, or do not get it done in three or two times. In China, some people are afraid of the practice of multi-star reception, and some people Try to stop, someone succeeds, how many people have it tested the ability and perseverance! The advantage of one-pot multi-star is that it can make the most of the reflective surface, reduce the space and space dependence, reduce the cost of the antenna, and switch quickly and without a pause, as if it is received on one star. The disadvantage of one-pot multi-star is that it requires a larger area of ​​antenna, and it is more difficult to support, fix and adjust the LNB; the strength of the "off-focus" received signal is reduced, and the more it is biased, the more difficult it is to achieve the entire viewing range all with a pot of receiving, at the same time along the LNB installation will affect each other when the spacing is too close, so it is difficult to use the two stars near the left of. The receiving method of the grade axis antenna uses the C and Ku joint antenna of the grade axis push rod. The installation details of the pole axis push rod on the antenna. A new four-link pole axis antenna uses the Ku antenna of the pole axis base. The details of the polar axis Ku antenna, the center of gravity balanced polar axis antenna, and the homemade manual polar axis Ku antenna. The polar axis antenna is to fix the reflection surface of the antenna together with the LNB on a rotating axis. This axis of rotation is basically parallel to the rotation axis of the earth. Because the axis points to the north and south poles of the earth, it is called the polar axis. The polar axis was first used in astronomical telescopes. In the observation, the astronomical telescope is driven by the polar axis to rotate in the opposite direction of the earth's rotation, which can offset the movement of the astronomical object in the observation eyepiece caused by the rotation of the earth. The vertical main shaft in the conventional satellite antenna ground structure is relatively simple, but to use azimuth, elevation and polarization angle three parameters positioning antenna. When for the stars, these three parameters also have to re-adjust, very inconvenient. After the pole shaft into the shaft of the antenna, when the antenna for the stars with the pole shaft to rotate, the azimuth, elevation and polarization angle automatically follow the changes, only one adjustment parameter, i.e. the polar axis around the corner. It can be considered that the azimuth, elevation, and polarization angles of ordinary antennas are additional parameters caused by the end of the rotation axis being parallel to the earth when these antennas rotate. Once the rotation axis is pointed correctly, the additional parameters are eliminated. Some star friends do n’t need to adjust the elevation angle and polarization angle when they change the polar axis, and they feel incredible! One of the keys to the realization of the polar axis antenna is to change the rotation axis of the antenna into an adjustable tilt axis, so as to adapt to the needs of different latitudes to be parallel to the rotation of the earth. The second key to the realization of the polar axis antenna lies in the polar axis drive, control and positioning device. Star friends can try to make a manual polar axis. It has no driving, control and positioning devices. With the polar axis scale directly indicating the accuracy of the satellite, the antenna can be rotated directly by hand. It is also very fast and convenient to change the star. Compared with the conventional antenna general large electric polar antennas, more polar seat can rotate, and an electric push rod days controller. Polar stationary housing part of the antenna reflector, which is mounted on the column head, the antenna can rotate about a fixed tilt axis of the polar base. The electric push rod is a driving component that pushes the antenna to rotate, and has a large pushing and pulling force. It is composed of a motor, a reduction gear set, a push rod and a support. There is a new four-link polar axis antenna, a driving mechanism It is more complicated, but it has more performance, and can overcome the shortcomings of the ordinary putter. The sky controller is the control part of the electric putter. There are a few keyboard and display human-machine interface components on its panel. It uses an independent power supply. Most of them have DiSEqC1.2 interface function, which provides power to the electric push rod, allows the push rod to be driven in a continuous or inching mode through the buttons, and can remember and set the position of the satellite. For the installation and debugging of this type of polar shaft, please refer to the related article by Mr. Zeng Wenming. Generally 1.2 meters small offset antenna can be driven by buying conform DiSEqC specification "level - horizontal mounting" (HH Mount) polar axis seat, change it to electric polar axis antenna. Such polar shaft seats currently available in China are: SPM-990, DG-120 (+), SG-2100, etc., their structure, size and control circuit are basically the same, the prototype is jaeger polar shaft seat. The control of the polar shaft base and the power supply part of the polar shaft base can use the 75-ohm coaxial cable originally used by the antenna. Since the polar shaft base uses the current provided by the receiver to the tuner, the current amount is limited, generally no more than 400 mA, so the DiSEqC polar shaft base can only be used on Ku antennas with a size of 1.2 meters or less. This polar axis antenna cooperates with the receiver with DiSEqC1.2 function, no need to add other components. When watching, as long as you use the remote control to select a program, you can automatically change the satellite. The receiver without DiSEqC1.2 function is more troublesome to use this kind of polar axis. It needs to be equipped with a sky controller. When changing stars, it needs to be operated by the sky machine. It can be expected that all receivers in the future will be equipped with DiSEqC1.2 or higher functions, which can be directly equipped with this type of polar shaft seat. The receiving card used by the PC also provides DiSEqC1.2 function, but the receiving card draws power from the PCL bus slot. The rated maximum current is only 400 mA, which is only enough to drive the LNB. It is difficult to drive the electric polar axis. For the installation, debugging, configuration and improvement of such polar shaft seats, please refer to Mr. Lou Jun's article "DiSEqC1.2Ku Polar Shaft Installation, Debugging and Use" and my articles "DiSEqC1.2 Polar Shaft Ku Antenna Improvement" and "XSAT" Instructions for installing polar axis antennas, etc. With polar axis base with one antenna to realize C + Ku dual band reception, you can achieve all signal reception throughout the day. In the receiver, the use of polar controlling the antenna, set only a LNB, to use two LNB (C + Ku), we should try to control the LNB by the switching signal, switching of the corresponding switch LNB. According to the introduction of "good" and "civilization" of the star power, choose the C-band and Ku-band LNB of the single local oscillator, you can use the 0 / 22kHz signal to switch. If the receiver can directly set the 0 / 22kHz signal, such as Thunder card-free machine, 610 machine, etc., then it can be easily realized by the one-pot + composite C / Ku high-frequency head with 0 / 22kHz switch. The machine can not directly set 0 / 22kHz. For example, the XSAT4 × 0 series receivers that are very popular at present, you must skillfully set the dual local oscillator, referring to the method of the above four-star receiver, use the receiver to use the dual local oscillator LNB At this time, the principle of okHz signal corresponds to low local oscillator and 22kHz signal corresponds to high local oscillator. The C-band parameters are transformed to control the 0 / 22kHz signal to achieve reception. If the Ku band uses a dual-local LNB that occupies the 0 / 22kHz switching signal, the C / Ku switching uses a 0 / 12V signal. At present, most receivers have a 0 / 12V voltage interface on the motherboard, but some machine menus have a 0 / 12V function, but there is no interface outside the machine. The 0 / 12V switching voltage needs to be drawn from the onboard motherboard. The 0 / 12V switch can be used in finished products, and it can also be modified with a live relay 13 / 18V or 0 / 22kHz switch. The advantage of the polar axis antenna is that it can receive the signals of various satellites with high quality in the entire receivable sky; the number of receiving satellites is many, up to dozens, the antenna occupies a small area, and the installation environment requirements are low, as long as a single The antenna feeder has simple wiring; it is easy and convenient to use when watching TV programs. The disadvantage of the axial antenna is that the one-time capital cost is relatively high; the loss is large after being stolen (damaged); installation, adjustment and setting are difficult, and it is necessary to wait for a period of star rotation when changing stars, up to tens of seconds , as multi-satellite pot or pan quickly; part of the power DiSEqC1.2 type of polar axis antenna to extra consumption of the receiver, in the summer, could lead to severe fever frequent power receiver for the stars. Conclusion Multi-star reception is the pursuit of Xingyou. It is a gradual process from few to many. Start with a star with a strong signal, and gradually develop to receive multiple stars with weaker signals. Comparing various multi-star receiving methods, multi-star receiving is the fun of star friends. Constant pursuit and continuous improvement not only cultivates ability, but also enriches life and enriches life. |
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