Sunbeam Microwave Engineering Co., Ltd. Chengdu, China's digital TV terrestrial broadcasting standards, the figures TV Transmitter Been rapid development, however, the creation of digital TV transmitter filter, multiple synthesizer needs, no formal standards, specifically in rural areas now Wireless Coverage Program continues to be adopted because the national standard DTMB trend, the requirement for more rural areas included in television copy number, the bigger the radius from the cover system, should be several high-energy single-funnel transmitter for multi synthesis, a set of antennas to be the greatest choice , synthesis filter may be the core of multiple aspects of the launch of their technical performance indexes from the system quite a bit, presently the only channels happen to be released in to the energy system, negligence producers to multiple synthesis techniques, but related, uses import multiple keyboards, time-consuming and costly and never set you back the output filter, multi synthesizer diverse demands that people find used the needs of some customers isn't practical. I would like this (to go over the filter-based) released his sights a little, and that we talked about together.
Digital TV transmitters actuator indications ought to be quite good, after the rear of solid condition energy amplifier, due to the energy Amps And a number of distribution and synthesis of systems will introduce nonlinear distortion and linear distortion. And solid condition energy amplifier is frequently Broadband Qualities, to acquire a standard band features, performance meets the machine needs from the output filter is important.
Now TV transmitter antenna tower on a number of TV and FM transmitting antenna packed towards the brim, and think about starting channels to improve the amount of antennas continues to be very hard, so a duplexer, multiplexer to ensure that multiple transmitters share an increasing number of customers transmitting antenna. Synthesis of those high-energy digital network ought to be requested what's there's no standard to follow along with. However, these synthetic network performance is dependent mainly on digital systems use filters, so seriously discuss the needs from the filter is essential. (Not the same as using technology to stream digital filter, which we tentatively transmitter output linear filter known as "digital systems filter" it, this paper known as the filter slightly.)
Output filter ought to be employment inside the needed frequency band-pass filter, should satisfy the needs from the energy capacity, within the pass band should meet a particular bandwidth needs, and really should be no more than possible because the amplitude of fluctuations and small delay. Digital TV also needs a steep transition zone so far as possible, to satisfy the particular stop band attenuation.
Primary qualities: 1. filter energy capacity.
Digital TV transmitter energy in line with the average band Energy Meter Volume, therefore the output filter should also have the ability to withstand the amount of average energy to define its energy capacity. However, this "bear" ought to be the number on the possible lack of a scientific concept. Used, it appears you will find two ideas. The first is the filter itself has better temperature compensation device, it enables greater Radio wave energy increases, permitting greater temperature rise, as lengthy because the curve with much drift, even when the spend is hot can also be allowed. I've come across a few of the import product is like this. The second reason is the consumer needs
insertion loss no more than possible, as well as the ranked energy, you can't possess a hot feeling. Magnitude isn't the concept. It appears that only following the provisions from the ranked energy maximum temperature rise of the amount of levels to some data illustrate the issue. Some customers even suggested synthesis system doesn't allow additional cooling measures, which is no excessively demanding. I've come across R / Of the 20KW transmitter output filter to include liquid cooling!
Open about using one finish from the short finish from the small , medium-energy coaxial resonant cavity filter is dependent around the capacity of their energy outdoors the cavity of how big the conductor, as the inner conductor diameter from the Q value selected through the determined. Generally the higher the exterior cavity for simple insertion lack of more compact, affordable energy just a little bigger. (This doesn't involve high-energy round waveguide type filter). Filter file is underneath the energy sub-output energy transmitter set. Generally used are:
20W, 50W, 100W, 300W, 500W, 1KW, 1.5KW, 2KW, etc.. This series also needs to have standard Caixing.
Radio wave energy to deal with around the filter definition, I suggest to: Canada ranked Radio wave energy, working a lot more than an hour or so, the temperature arrived at homeostasis following the filter, using the temperature measurement of temperature and also the greatest point, and also at 70 degrees is "The greatest temperature difference t". Once the temperature stability from the filter to 2KHz / K time, t 15 C, filters should have the ability to steady work. This meaning of words using the data compared to hands touch ought to be stated the scientific point, I don't know any objection? Could be launched for discussion.
Digital TV having a digital filter additionally to thinking about the capability of average energy, we ought to also begin to see the peak of digital television signals? Level ratio, DMB-T our peak? Level ratio of 7dB (5 occasions). 1KW digital filter that's that need considering to deal with the utmost peak energy as high as 5KW! Therefore, picking a fittings and internal lighting so far as the consideration to become carefully designed, or prone to cause high-frequency arcing.
2. Insertion Loss Filter insertion loss is understood to be the middle frequency f. Reason for insertion loss. The dimensions and frequency of labor, such SPINNER companies employed in the UHF filter (Model BN61, 63,67), much more the UHF 470MHz low insertion loss .45dB, as the insertion loss could be high-finish 860MHz Zuodao .65dB.
Insertion loss and energy capacity can also be associated with the higher energy capacity outdoors the conductor the higher the body cavity, such SPINNER companies 2.5KW filters (BN61.63.17) at low frequency can be achieved .45dB, as the 200W filter device (BN61.63.66) are only able to achieve .9dB.
Insertion loss values of negative and positive design and manufacturing processes are carefully related. Cavity loss such as the current flows with the conductive cavity top of the ohmic loss, fittings and tuning components, contact resistance loss, losing the development of welding quality. There cavity inappropriate media, will the development of dielectric loss. Once we attempted to stay with FM PTFE cavity lengthy on support inside the conductor, the end result clearly elevated insertion loss .07dB. A design should have the right filter to make sure correct processing. Plating quality, adjust the standard should be guaranteed to obtain a lower insertion loss. We've experienced, having a manufacturing design sketches in various industrial facilities, insertion loss vary broadly. Following a lengthy test, the Division St. filter processing quality of the organization more stable.
3. degree gang of spectrum isn't flat
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