Documentation
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Info 3 (November)
- General Information: Televes France +
- FAQ: “Full HD” and “HD Ready” televisions vs High Definition DTT +
- Product News: PRO Easy-F Connectors +
- Your Pictures: An umbrella for a satellite dish +
- Ideas: Measurement of optical attenuation without a light generator +
- Real Installations: Horizontal Fibre Optic Distribution in Auxerre +
- Training: The value of Noise Figure in LNBs: interpretation +
Televes France |
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After just over a decade of operation, Televes France is placed as one of the leaders of the sector. |
growth is characterized by its wide range of products - developed to provide solutions to the professionals -, its efficient logistics, its fast and professional technical support and its personalized training. |
performance of the DAT HD BOSS antenna, the AVANT 3 and AVANT HD programmable amplifiers, the H45 meters or the T05 and T0X headends. Products that represent the Televes brand and are recognized by most of the professionals in the industry. |
Pro Easy-F connectors |
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The evolution of the mobile network technology of 4th generation is known as LTE (Long Term Evolution). |
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other common extender.
The coaxial cable connection becomes a fast and easy operation: not having different pieces makes it ideal when cables are in locations where manipulation of devices is difficult. Only two movements and a perfect connection will be made |
“Full HD” and “HD Ready” televisions vs High Definition DTT | |||||
Lately, television sets have been changed with the arrival of the DTT. In most of these televisions you can see logos related to HD (HD ready, HD ready 1080p, Full HD, …), that refer to the screen resolution necessary to reproduce High Definition contents. |
However, this does not necessarily imply that such TVs are ready to receive HD DTT. For this, you need a screen with the required resolution, but the TV set also has to be equipped with a MPEG-4 tuner. |
capable to receive MPEG-4 contents is not common; that's why many users that have purchased televisions with built-in DTT receiver and with logos related to HD will need |
An umbrella for a satellite dish
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Measurement of optical attenuation without a light generator The same way you could use a broadband amplifier without input signal as an all-band noise source to be able to obtain the frequency |
response of a network, in optical networks an optical transmitter could be used as a light source for the measurement of optical attenuation. |
The +3dBm delivered by an optical transmitter of Televes (ref. 8674) can be used as a reference value in the H45 meter equipped with optical interface. |
Horizontal Fibre Optic Distribution in Auxerre | |||||
ETS Morriset is a telecommunications installation company that has made its first satellite signal distribution via fibre optics. |
The value of Noise Figure in LNBs: interpretation | |||||
Traditionally the quality of a LNB has been determined by the noise figure (NF). Currently, the values indicated in most of the technical specs are driven more by marketing criteria than real performance. |
because it is only there where we can appreciate the noise levels. The reality that this graphic is pointing out is that yes the LNB of our competitors has a higher gain but the C/N, that is what it is really important, is 3dB lower. In terms of system efficiency, the difference in the performance of the two LNBs will be higher than the difference that you will get when using an 80cm dish instead of a 1.10m dish. In other words, an 80cm dish using a Televes’ LNB 7475 will give a better overall performance than a 1.1m dish with one of our competitors LNBs. Even without using graphics like the one above, simply by measuring the C/N by means of the H45 Televes meter it would be enough to demonstrate the non-sense of evaluating the quality of the LNB based on the NF (0.2dB) parameter only. The phase noise In those LNBs that are going to be used to receive DVB-S2/HD services the phase noise is an even more important parameter than the NF; something that is completely ignored by those ones that assume a direct relation between quality and NF. The DVB-S2 standard uses most commonly an 8-PSK (Phase Shift Keying) modulation. This modulation uses 8 symbols to transmit the information, as opposed to QPSK, modulation most commonly used to transmit SD (Standard Definition) services, that uses only 4. This difference makes the possibility of having interference between symbols in an 8-PSK modulation more likely than in a QSPK. So the “purity” of the local oscillator of the LNB is a key parameter to avoid this source of interference that could generate breakage of the picture. The parameter that measures the “purity” of the signals given by the local oscillator (LO) is the phase noise. Televes‘ LNBs have a phase noise higher than 75dBc@10KHz that is what Astra |
specifies for satellite digital services. The graph below shows how the phase noise is measured by our quality control department. This is one of the several parameters that we measure when approving a LNB. |
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