DIPOL Weekly Review - TV and SAT TV, CCTV, WLAN

Faster wireless transmission - towards 4G. Lately, fourth generation wireless networks have been defined. The 4G system should guarantee mobile data transfer rates of 100 Mbps, and in the case of fixed equipment - 1 Gbps.Development of mobile technology in the direction of 4G goes through three channels: WiMAX, UMB, and LTE.

• WiMAX is the most advanced technology as regards the number of implementations. The concept of building all-American 4G network based on WiMAX is strongly supported by Sprint company. Until recently, a problem was the lack of dedicated mobile devices. But in September Motorola presented in Chicago working prototype of mobile terminal for metropolitan areas. It seems that development of nationwide WiMAX network has been given a new impulse.
• UMB (Ultra Mobile Broadband) is an extended version of cellular CDMA2000 standard. Its advantage over WiMAX is to be higher throughput - up to 275 Mbps.
• LTE (Long Term Evolution) - it is evolution of 3G (UMTS) system, with transmission speed up to 100 Mbps. Currently expanded UMTS systems employing HSDPA technology (called GSM 3.5 G) offer theoretical throughput up to 14.4 Mbps (practically ca 7 Mbps).

All the technologies use OFDMA (Orthogonal Frequency Division Multiple Access) modulation that allows high transmission rates due to many subcarriers and MIMO (Multiple-Input and Multiple-Output) implementations - multiple antenna transmission.

4G networks will use MIMO technology

Quad LNB and terrestrial TV. The enhanced Quad converter A98262 is equipped with four integrated satellite combiners. The solution allows to combine signals from terrestrial antennas. At the four outputs there are complete SAT/TV signals that can be distributed in the installation and are available at satellite outlets (the outlets ensure extraction of the signals suitable for sat receiver, TV set, stereo). This solution enables reduction of cables in the home.
Notice! The combined signals cannot operate with DiSEqC switches, so the LNBs are not suitable for "doubling" on one satellite dish. In other words, the converters are fit for reception from one satellite location. For receiving two satellites one should use Quad Monoblock converter A98261 and satellite/terrestrial combiner R85248 (it does not pass DC power to preamplifiers).
The cabling installation should be made with high quality cable guarantying stability of parameters and many years of use, e.g. TRISET-113 E1015_100.

The QUAD LNB A98262 allows to use four sat receivers without a multiswitch

Lossless splitting of cable TV signal for multi-room TV/video installations. Most of antenna amplifiers cannot be used for this purpose, due to unspecified parameters in the special cable channels. The void is filled by the RF amplifier AI-223 R90452, used as distributing device in small or private antenna installations, to ensure proper level of signal for multiple receivers. The amplifier works in full FM + TV band 86 - 862 MHz. As there are no empty spaces in the working band, the amplifier can be used in any cable network. Gain adjustment allows adequate correction of signal loss in cabling. The amplifier has a passive return channel 0 - 65 MHz, which allows to connect a cable modem. It also enables operation of remote control extenders, e.g. Signal-Link R93109.

AI-223 R90452 is used as distributing device in small or private antenna installations, including cable TV.

Splitters versus taps. Inexperienced installers attempt to do middle-size installations using only splitters. They put forward the argument indicating low attenuation of splitters. But analyzing properties of such network, we'll show that it is unacceptable.
Splitters should only be used for dividing the signal into a desired number of sections. The main reason is low separation among outputs of a splitter. Together with specific feature of TV tuners - they ensure proper matching only for tuned-in channels - the low separation favors the spread of other signals' reflections within the whole network. So the splitters may be employed only for small-size antenna networks, having several outlets. Bigger installations, with over 20 outlets, require to use taps, and splitters should be only applied to distribute the signal to taps. The unused outputs of the splitters have to be closed with 75 ohm terminating resistors.
The signal reflexions cannot be eliminated completely, but can be reduced to the levels that do not harm overall system quality. When using taps instead of splitters (tap attenuation 12 dB to 20 dB), the reflected signal comes back to the network (adequately) 24 to 40 dB lower than the useful signal, so it will not be practically noticed as a ghost image.
Implementation of taps, especially in larger network, requires high signal. The best solution is use of channel amplifiers, e.g. ZG-401/601.

Passive elements for antenna installations - Signal

Signal taps

CCTV monitoring in sacred places. Practical effectiveness of CCTV system should be based on its deterrent function. In general, the cameras have to be mounted in visible locations, and additional plates or stickers should inform that the place is monitored. In the case of historic churches/temples the cameras should be visible only outside.
There should be strict limitations inside a church or temple - the cameras can only be installed e.g. high above the altar, and never in the area for the congregation, especially in the case of PTZ devices.
Some cameras may only be perceptible when they monitor a precious object, e.g. a panting, but they are only allowed to watch its closest surroundings, not the people standing around.
Analyzing the purpose of CCTV installation one should realize that modern CCTV systems can substitute alarm installations, expanding a lot their typical functions. The sensors of an alarm system can trigger a danger signal, but they are not capable of recording the event, the face of the perpetrator etc. CCTV system with motion detection function or with additional sensors can easily do the job.
In busy places, there are indispensable color cameras - they enable the staff to identify the people. But the contractor should ensure proper operation of the cameras also in low lighting conditions and at night. For this purpose the best choice is day/night version. The day/night camera SN-468C M11202 ensures high resolution (480 TVL) and NightVision function.

How to choose HDD capacity for IP CCTV system? The specification of an installation contains the period of registration demanded by the customer/investor. To meet the expectations the contractor also has to take into consideration the number of employed cameras, image quality, and recording speed (fps). Below we show disc space needed for archiving video material recorded by ACTi devices using MPEG-4 ASP compression.
Example: 8 cameras, D1, 8 fps, 7 days - it is needed at least 302.4 GB of disc space.
The manufacturers of IP CCTV devices employ various compression methods (which also have different bandwidth requirements), so the specific needs may differ from this example.

MPEG compression - part 2. MPEG-4, aside from the methods inherited from MPEG-2, uses very effective algorithms of Wavelet compression. Better quality of transmitted MPEG-4 image, despite smaller data stream, is the result of coding whole moving objects (Shape Encoding). MPEG-4, besides analyzing independent blocks of the image, recognizes and compares objects in consecutive frames. They are isolated and coded independently from the background. The idea allows to minimize the data needed for description of the movement of complicated objects built with many macroblocks - VOP (Video Object Planes) on a fixed background. An example may be the moving face of the cashier at a gas station against the background of shelves etc. The MPEG-4 standard introduces VOPs of I, P, and B type, similarly to GOP (Group of Pictures) in MPEG-2. Thanks to VOPs it is possible to record the changes of location, shape, and texture of the image elements so effectively as in the case of GOP.
MPEG-4 also uses GMC (Global Motion Compensation) technique. Due to GMC, the effects like zoom or camera rotation can be described by a limited number of parameters and the previously saved information.

Vandal-proof cameras. The housing of vandal-proof camera is made of metal and polycarbonate dome. Polycarbonates are particular group of thermoplastic polymers that are highly transparent materials characterized by superior mechanical durability, especially the resistance to impacts. Hardness and structural integrity of polycarbonates is similar to that of aluminum. The windowpanes made of polycarbonate are used in bathyscaphes, airplanes, assault helmets.An example of vandal-proof camera is C-3844-01A1 M10735.Main advantages of the M10735 camera are:

• Special construction of the camera housing:
• smoked dome made of polycarbonate - it is difficult to notice the direction of operation,
• dome shape improves resistance to impacts,
• special construction allows to hide the cable in the ceiling - it additionally protects the camera post,
• possibility of wall mount - extra options enable the installer to use dedicated brackets, also the version with hidden cable,
• possibility of changing the lens, which allows to adjust viewing angle to the specific job, e.g. monitoring of big entrance hall, or narrow hallway.

Vandal-proof camera M10735

Speed versus range. Sensitivity of WLAN devices depends on the implemented modulation and coding, and it greatly influences transmission speed. The 802.1b and 802.11g standards use ARS (Adaptive Rate Selection) mechanism, choosing the maximum possible speed. As an example, in the case of 802.11b, the PCI WLAN adapter TP-Link TL-WN551G N2970 has sensitivity of -89 dBm at 1 Mbps and -85 dBm at 11 Mbps. The difference in sensitivity of 4 dB means two times larger range at lower speed. There is similar situation in the case of "g" standard where the difference in sensitivity between the slowest and fastest mode is as much as 20 dB, which translates into 10:1 ratio of the ranges.

Efficient two-band mini PCI WLAN adapter. Mini PCI TP-Link TL-WN662AG N2966 is compliant with IEEE802.11a/b/g standards and operates at both 2.4GHz and 5GHz frequency bands. The employed Super G technology enables the user to reach even 108 Mbps transmission speed. The mini PCI card TL-WN662G is designed for use in mobile computers and RouterBoard platform with Mikrotik system. Main features:

• IEEE 802.11a/b/g ,
• 2 x uF connector for external antenna ,
• mini PCI interface,
• Super G technology (up to108 Mbps),
• eXtended Range (up to 9 times broader range in comparison with regular devices),
• Seamless Roaming (switching among APs).

The mini PCI card TP-Link TL-WN662G 108 Mbps is wireless adapter working in all available standards (IEEE802.11a/b/g).

SatKrak - Oct 18-20, 2007 - trade fairs change their face. Only several years ago participation in a trade fair was the quickest way to "touch" the innovations. During big events the companies promoted their new products. Today this function is being marginalized. It is much more important for the representatives of the companies to get in touch with their partners, mainly the leading suppliers, and to negotiate the conditions for good cooperation. For the buyers - it is an opportunity to learn both the details of the offer and general trends in the field - it will be enough to take part in the courses and conferences organized during the event.

During the exhibition there will be possibility of direct contact with our marketing and technical specialists - we invite everyone interested in cooperation in the fields of SAT TV, CCTV, WLAN. Our existing and prospective partners can negotiate prices and take part in the courses. The guideline of Dipol's exposition at SatKrak is "Multimedia Home". We will present in detail the idea for designing and implementing structural cabling that combines all services needed by the residents of modern homes.

We will present a new Dipol website on the show. After 11 years we have changed design of our site, adding a lot of functionality.
SatKrak