In the debugging of receiving satellite TV or in use, it is often found that the received signal quality is not good, and its performance is as follows: 1. The signal is intermittent and the picture sometimes has a mosaic. 2. The picture is jittery and sometimes there are two pictures above and below. 3. The signal is erratic and the signal is erratic. 4. The sound is intermittent and the sound is turbid. When these phenomena occur, some people tend to focus on the star. They think that the antenna is not aligned with the satellite, and it takes a lot of time to adjust the antenna. The result is still unresolved. In fact, there are many reasons that affect the quality of the signal. It should be analyzed and eliminated one by one to satisfy the debugging and receiving.
In the commissioning, we must first carry out serious inspections on the supporting equipment, and pay attention to every link in the commissioning and installation. We must not rush to seek success. We must understand and confirm the influence of the local environment on the quality of the received satellite signals. So as not to give up.
First, the inspection of equipment1. Digital receiver: It should be stable and reliable, and the after-sales service and brand reputation are better. It is best for beginners to purchase a receiver with signal strength display, low threshold and high quality. The function is not necessarily good. It is required to be practical. Receivers with high thresholds often do not receive signals when viewing weak signals. Especially when the margin of other equipment is not very large, the threshold of the receiver is very important. For example, in the same supporting equipment, different quality is used. The receiver, the poor receiver can not receive the weak signal, or the picture is unstable, there are mosaics and so on.
2. Antenna: The antenna is the key supporting equipment for the front end of the signal quality. The accuracy of the antenna is very particular. Different types of antennas, some antennas have great advantages and disadvantages, and the antennas with poor quality or deformation, even if the antenna diameter is used too much. To no avail, the focus does not know where to go, and the results are adjusted and adjusted. This example has been heard. In order to ensure the excellent signal quality, the antenna should not be blindly pursued with small caliber, or superstitious large caliber, but the accuracy of the antenna pot surface should be emphasized. As long as the aperture of the antenna meets the receiver threshold requirement of the received signal.
3. High-frequency head: The quality of the low-frequency high-frequency head is difficult to guarantee. Each batch is still different. The quality problems of the high-frequency head are mainly reflected in the unstable working performance, such as the local frequency drift and poor thermal stability. The frequency band has poor consistency, low gain, etc., in use, the signal will be unstable, if it is hidden, some frequency bands are good, some frequency bands are poor, and even the low frequency gain, high frequency head, received signal The quality is obviously not good. I have done experiments, using the same antenna and receiver, to receive the same program, replacing the high-frequency heads of different brands one by one, but found that the quality is different, even in different batches but in the same brand of tuner There are also differences. We have also found a serious unqualified product with a 50MHz local oscillator drift. Therefore, it is necessary to understand the quality of the used high-frequency head during debugging. It is best to check it first.
4, RF cable and F connector: cable and F head, although not critical equipment, but if sloppy and improper selection, it will affect the quality of the signal. If the core of the RF cable is too thin and the screen is too thin, the leakage and attenuation of the signal will be large, resulting in a decline in signal quality. The connection between the F head and the cable should also pay attention to the process. If the connection is not good, the shielding net and the core wire will be short-circuited, or the shielding net and the F head will be broken. If the waterproof treatment is not good, the wind and rain will cause oxidation. , poor contact with the high frequency head caused a significant drop in signal quality. In addition to the use of high-quality cables and F heads, it is necessary to pay attention to reliable connection and rain.
5, a variety of switch: When you need to receive multi-star or multi-family reception, you need to use the switch, such as: 0 / 12V, 13 / 18V voltage switch; 0 / 22KHz, DisEqC switch; various power points Instruments, lines, etc. The quality of these switchers varies, and the inferior switch signal loss is very large, which seriously affects the viewing quality. It is also very important to select a good switch.
In short, the reason for the deterioration of the received signal due to the poor material quality is that many of them are seen, and the quality of the received signal is clearly reflected by the comparison of high-quality equipment, and some people have these small auxiliary equipment and equipment. The process of adjustment is often negligent. If you adjust the star to the height of the first time, you should calmly think about whether it is the above reasons.
Second, installation and commissioning1. After selecting high-quality equipment, the accuracy of the star is the first level to determine the quality of the received signal, so be patient, especially for the first-time person, unfamiliar with the position, and lack of experience, this You can use some auxiliary equipment for tuning stars, such as compass, star finder, inclinometer and so on. For this experience, it is best to read some articles about electronic publications, such as "Vision Media". These newspapers are the best mentor and friend, and you must have the knowledge and experience you need most.
2. Try to avoid debugging on rainy days when searching for stars. The bad weather is very detrimental to the signal. You should also know whether there is interference from sunspots during debugging, and whether the clouds are too thick. Another thing to note is that even in clear weather conditions, the location of the source of the transmitted signal is bad, the signal strength is affected, or the transponder that happens to be debugging is off, or the parameters have changed. Although this situation is rare, it is sometimes coincidental. If you are inexperienced for the first time, you can use a time-sharing method or debug other transponder programs.
3. In the debugging, avoid the obstructions in front of the antenna, such as houses, trees, etc. After using the compass to determine the general orientation, visually measure the distance of the obstructions in front of the antenna. If there is any influence on the viewing, the antenna should be moved to change the position.
4. In the commissioning, a set of transponders of the strongest signal in the satellite should be selected. After receiving the signal, fine-tuning is performed to the optimal point, so that the weak signal can also be satisfactorily viewed.
5. In the debugging, sometimes it will encounter nearby microwave interference, mainly in the C-band. In the frequency range of 3.4-4.2 GHz, there are indeed various microwave signals. When debugging the frequency of this group of transponders When it is close to the transmitted microwave frequency, it will cause interference, which is usually called co-channel interference. In this case, the signal cannot be downloaded. The solution is to add a metal shielding net in front of the antenna to absorb the interference wave. With isolation, if the effect is not good, you can only give up.
The various reasons for the above analysis are often encountered in debugging, so it is necessary to analyze them carefully, eliminate them one by one, and take fewer detours.
Among the small antennas, an antenna with a rocker to adjust the screw to change the azimuth and elevation is preferred because the rotation is smooth, stable, and flexible, debugging is not only easy, but the accuracy is guaranteed, but unfortunately such antennas are rare. It's not easy to buy. You can only choose the better quality among the common antenna brands. Use your hand to slowly shake the antenna. After coarse adjustment to the signal, slowly fine-tune the fine-tuned azimuth. The tube hand or the movable wrench slowly change the tension of the left and right fastening screws (fixing the antenna back to change the azimuth), and changing the tension of the left and right thread pitches to achieve the fine adjustment of the antenna. Azimuth, until the received signal is the strongest, the picture quality is the best, then the azimuth of the antenna, the accuracy should be relatively high. To fine-tune the elevation angle, you can place an inclinometer or a protractor on the antenna to directly see the degree of change when the elevation angle is reached, until the signal is strongest, and finally tighten the screws for each fixed antenna.
After the star-hunting debugging is completed, rain protection should be considered. Rainwater is one of the main killers for signal attenuation. To prevent rain and fall, please refer to several methods previously introduced in this magazine. The simplest method is to use plastic bottles. Such as a 2 liter beverage bottle, etc., the bottom of the bottle is removed and cut into a slanted sleeve on the high frequency head, so that the rain can not fall on the high frequency head, but when the rain on the pot surface is too much, the signal attenuation is still large, Make a flashing on the top of the antenna. If there is space on the balcony, you can move the antenna to the balcony. The ceiling of the balcony can block the rain.
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