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1
Program educațional DIPOL - sisteme SMATV și CCTV
În cadrul acestui articol sunt înfățișate exemple de construcție a diferitor sisteme în Școlile de Arte și Meserii. În plus, sunt listate alte articole ce ajută la înțelegerea dificultăților întâmpinate în practică din domeniul electronicii.
2014-01-07
2
Symbols used in diagrams of antenna installations (Polish norm)
Symbols used in block and wiring diagrams of community antenna installations in Poland (information suitable for Polish users only)
2007-01-01
3
Locaţiile şi parametrii emiţătoarelor DVB-T2 din România.
Locaţiile şi parametrii emiţătoarelor terestre digitale din România.
2016-10-29
4
Installation planning - individual and community antenna systems
Specific conditions and requirements, concept, design, future development, cabling.
2007-01-01
5
Bazele sistemelor de distribuţie TV-CATV
Sistemele de distribuţie CATV pot fi definite ca sisteme în care compensarea atenuării din reţea se face într-un punct central de un set de amplificatoare. Amplificatoarele pot fi conectate şi în cascadă.
2007-01-01
6
Măsurarea semnalului TV/CATV
Majoritatea parametrilor de semnal TV pot fi măsuraţi folosind aparate de măsură speciale. Aceste măsurători trebuie făcute pe hârtie în momentul proiectării sistemului şi apoi pe teren la punerea în funcţiune. Măsurătorile identificarea rapidă a erorilor apărute în etapele de proiectare şi implementare.
2007-01-01
7
Distribution of digital signals in cable TV systems
QAM modulation is optimal for cable networks. It is used in cable band/hyper-band (S channels) and UHF band. Due to the need of compatibility with channel raster and transmission requirements, there are used 8 MHz channels (MPEG-2 compression, QAM modulation).
2007-01-01
8
Maximum output level in active elements of community and cable networks
One of the important parameters of amplifiers is their maximum output level. It is the level which can appear in the amplifier output without exceeding an acceptable level of nonlinear or crossover distortions.
2007-01-01
9
Digital satellite broadcasts
Thanks to digital technology, satellite industry has increased the number of channels that are broadcast from one transponder - there may be transmitted 5, 8, or even more TV programs. It lowers operating costs and makes possible to multiply the offer from a single satellite. The important factor is compression level that can be changed according to the intended quality of the image.
2007-01-01
10
Electromagnetic compatibility (EMC)
RF cable network should fulfill regulations of electromagnetic shielding. It cannot radiate energy that exceeds determined level and it should be resistant enough to outer electromagnetic radiation.
2007-01-01
11
Compression of video and audio signals
MPEG-4 is the newest video compression standard which quickly becomes popular, also in the case of video streaming. In comparison with previously presented standards, it integrates effective methods for multimedia data.
2007-01-01
12
Separation between outputs of splitters
Separation between outputs of splitters (crosstalk attenuation) is very important parameter of the devices. It determines level of interferences coming from other branches of the network connected to the splitter. It should be as high as possible.
2007-01-01
13
Theory and use of channel amplifiers
A common problem that is encountered in terrestrial TV antenna installations is unbalance of the level of received channels, often about 10-20 dB. In case of small installations (5-20 outlets) such a difference (not recommended) usually doesn't make any trouble yet. It is the real problem for bigger installations, where the difference of levels at the input is increased by inconstant (being a function of frequency) attenuation of cables and may easily exceed (in an outlet) the accepted limit (12 dB) all over the band.
2007-01-01
14
Splitters and taps
To ensure proper S/N ratio, the isolation between any two receivers should be at least 50 dB.When the receivers are connected to the same tap, the isolation depends on the Ao, A, and As attenuation, and the lengths of the cable between tap outputs and subscriber outlets.
2007-01-01
15
Filters in TV antenna installations
An ideal band-stop filter has no attenuation in the pass-band, 90-degree steep slope, and infinitely high attenuation in rejection band.
2007-01-01
16
Grila de frecvente a canalelor TV (PAL BG/DK)
În România este folosit sistemul PAL cu norma TV D/K şi numerotare continuă (după canalul S8 urmează canalul S9). Am prezentat, de asemenea, şi sistemul PAL cu normă B/G folosit mai ales în ţările din Europa de vest. În acest caz, - în unele dintre ţări - există un salt de numerotare între S8 şi S11.
2007-01-01
17
Tabel conversie - dBuV la uV/mV
În tabelul de mai jos puteţi găsi corespondenţa dintre nivelul de semnal şi tensiune.
2007-01-01
 
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