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

Television - the medium of the future. The American giant, Intel, associated primarily with computer industry only, decided to enter the television market, with a processor being the basis for running multimedia applications in STB (Set-Top-Box) devices, Blu-ray players, and televisions. "The future of TV is the future of Intel" - was the message at the annual Intel Developer Forum. Eric Kim, Senior VP of Intel's Digital Home Group, also said that "Broadcast is not going away".
The main objective of such projects is to combine the ease of use of TV with the possibilities offered by the Internet. The newest Intel Atom processor CE4100, presented on the last day of IDF in San Francisco, is built in 45 nm technology, with 1.2 GHz clock speed. This System-on-Chip (SoC) can decode two 1080p video streams with various high-end audio codecs, providing MPEG-4 support and 3D graphics capability. It consists of a programmable 2D/3D graphics processor Intel GMA 500, video controller, display and transport processor, and dedicated security processor.

The new Intel CE4100 media processor (on the left) and its predecessor
(source: news.cnet.com)

TV sets equipped with such processors will create new impressions when watching television, based on information from the Internet. This way, at the same time the user could watch any program and talk with friends online or use some mini-applications (so called widgets).
Ready-to-use solutions were presented by MySpace at the beginning of this year. In addition, since 2010 Intel chipsets should support Adobe Flash 10, which the manufacturer views the future of interactive television.

According to Justin Rattner, Intel's chief technology officer and Senior Fellow, "By the year 2015, you can expect 15 billion consumer devices capable of delivering TV content with billions of hours of video available"... "We'll need much more sophisticated ways to organize content and provide it on demand. Intel Labs researchers are working on evolving technology so people can get the TV content they want, when they want it and wherever they want it."
Cisco also sees the future of television bright. According to its projections in the year 2013, 90% of IP traffic will be associated with video streaming, with 60% of video content delivered using IP technology.

The new processor is the foundation for the production of affordable TVs that support three-dimensional images. What until recently was reserved only for the IMAX cinema goers, in the near future it will be available in every home. To bear out this opinion, we inform that already in 2010 the British television provider, Sky, will launch the first 3D channel, of course in high definition.

MAC layer - a few words on WiFi - part 7. Characteristics of OFDM for IEEE 802.11 a/g.
In 802.11 a/g standard it is possible to use quadrature amplitude modulation 64-QAM (6 bits per symbol), 16-QAM (4 bits per symbol), or phase modulation QPSK (2 bits/symbol), BPSK (1 bit/symbol). There are also used different levels of forward error correction (FEC 1/2, 2/3, 3/4).

In 802.11 a/g devices the OFDM modulation process is carried out using Inverse Fast Fourier Transform (IFFT) with the following parameters:

• sampling frequency 20 MHz, 64 points;
• OFDM frame length of 80 chips (data: 64; prefix: 16).

The OFDM system used in 802.11 a/g employs 48 subcarriers for the data (numbered from -26 to -22, -20 to -8, -6 to -1, 1 to 6, 8 to 20, 22 to 26) and 4 subcarriers for the pilot signals (numbers -21, -7, 7, 21). 12 subcarriers do not carry any information. Pilot signals are used for frame detection, carrier wave frequency offset estimation and channel quality assessment. The subcarrier 0, being the carrier wave frequency, is ignored. Frequency spacing between subcarriers is 0.3125 MHz (20 MHz/64) and corresponds with the time domain impulse width of 3.2 microseconds. The duration of a single BPSK-OFDM symbol is 4 microseconds.

OFDM composite signal generated in the baseband and moved by heterodyning to the appropriate frequency band (5 GHz in 802.11a systems, 2.4 GHz in 802.11g systems). In Europe, the 5 GHz band includes 3 sub-bands: 5150 MHz to 5250 MHz, 5250 MHz to 5350 MHz, and 5470 MHz to 5725 MHz. The frequency channels in the 2.4 GHz band are the same as in the case of 802.11b systems.

In 802.11a/g systems, data rate on each subcarrier is proportionately lower compared with the system in which data is transmitted on a single RF carrier wave, such as 802.11b. It results in multiple increase of the time of a single OFDM symbol, and consequently increases the resistance of the systems to the effects of multipath propagation.

802.11g systems are different from 802.11a ones not only due to the operating band. 802.11g systems have to be backward compatible with 802.11b devices. Every AP and user's device can change the network mode from OFDM to DSSS. This way, in the 2.4 GHz band the "new" terminals compatible with 802.11g, can be handled by the "old" infrastructure compatible with 802.11b, and the "new" infrastructure can handle the "old" and "new" terminals.

Due to the fact that 802.11b devices do not detect the presence of OFDM radio signal, backward compatibility of the 802.11g equipment requires to use RTS/CTS (Request to Send / Clear to Send) signals in DSSS mode. Thus, any 802.11g terminal that intends to transmit data, first sends RTS signal compatible with 802.11b. This signal is received by the AP and some other terminals. In response, the AP sends CTS message compatible with 802.11b, which is received by all terminals in the network. Then, the terminal which has initiated the communication sends the package in OFDM mode, and the AP acknowledges its reception in that mode. The transmission of the initial, additional information results in a noticeable reduction of transmission capacity in 802.11g systems operating in the mode compatible with 802.11b.

Transmission of OFDM packets in the mode compatible with 802.11b

Highest quality cameras from Sunell. Sunell cameras have a good reputation among customers due to high image quality and stable operation. For years Sunell company has been at the forefront of Chinese companies producing the highest quality cameras using the latest technology. Recently, the offer has been enriched with two new cameras:

New DVRs from KPD series. DIPOL introduces two new models of digital video recorders. One of them is 8-channel KPD-676Z M8708, the second - 16-channel KPD-678Z M8716. Both models belong to the basic segment with affordable prices. The DVRs can record compressed video (MPEG-4) with resolution of 704 x 576 pixels at frame rate of 6 fps. They also have possibility to record 4 audio channels, perform PTZ control, cooperate with alarm sensors. The DVRs allow continuous recording, recording on a schedule or recording triggered by motion detection. Due to LAN interface, they can be operated remotely via computer network, using client software or IE browser.

Megapixel monitoring in a high-riser on the Philippines. Seven-story building of M! Business Center has been protected by megapixel video surveillance system based on ACTi equipment. In order to avoid problems with power supply (additional installation), the system employs PoE technology that utilizes the structural cabling.
The system consists of the following ACTi devices:

The whole system is managed via proprietary ACTi NVR software that is supplied (for free) with ACTi equipment. The software allows remote access to the system via the Internet.

Diagram of the main components of ACTi megapixel surveillance system implemented in M! Business Center on the Philippines

Installation of GSM repeater in one-family house. In places far from cities there are problems with mobile coverage. Such problems may occur when the house is located at large distances from the cellular base stations, or when it is situated in a valley. The solution to this problem is to install appropriate GSM repeater. The optimum solution is to use Signal GSM-300 repeater A6760 and several indoor Trans-Data antennas.

Below we present the installation scheme for one-family houses:

The set of devices for one-family house

The set includes:

New Access Point from TP-Link - TL-WA500G AP/APC/WDS 2.4 GHz with PoE option. The Access Point TL-WA500G N2941 uses 802.11 b/g standards and provides many functions and modes of work: AP, AP Client, Repeater, Bridge (Point to Point, Point to Multipoint). The AP offers functions that are very useful for applications in small WLAN cells. WPA/WPA2, WPA-PSK/WPA2-PSK, TKIP/AES and MAC address filtering can ensure high security level. TL-WA500G is especially effective as cheap APC device. Another advantage of the device is ability to connect an external antenna. User-friendly interface and simple setup will not cause problems even for novice users.

Access Point with eXtended Range: TP-Link TL-WA500G
(AP/APC/WDS 2.4GHz, PoE)
N2941

We have written about:

Recording of road traffic with the use of ULTIAIR devices and IP CCTV cameras from ACTi. Failing to yield right of way and going over a red light at the crossroads are important reasons of collisions and accidents in large cities. It is often difficult to establish the fault of the driver who caused the collision...
- archive DWR of Feb. 23, 2009

How to combine two SAT signals into one cable - TWINSENDER. A common mistake made when wiring houses and apartments (or installing a satellite TV system) is putting only as many cables as needed at the moment. Most of satellite dishes have been installed with single LNBs, each connected with the sat receiver via single coaxial cable. However, modern sat receivers with recording functions (PVRs) have two tuners that require two independent signals...
- archive DWR of Jan. 12, 2009

How to set OSD cameras? Application of DSP (Digital Signal Processor) allows to enhance the array of camera adjustments...
- archive DWR of Feb. 18, 2008

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