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

DVB-SH - Satellite services to Handhelds. DVB-SH standard is one of the methods used for transmission of digital video to mobile devices. The DVB Steering Board and European Telecommunications Standards Institute (ETSI) have approved the specification in February 2007. DVB-SH is a hybrid (satellite/terrestrial) standard derived from DVB-H (Digital Video Broadcasting - Handheld) and SDR (Satellite Digital Radio), with architecture similar to Korean S-DMB (Satellite - Digital Multimedia Broadcasting).
As mentioned, DVB-SH is to use hybrid technology - a high power geostationary satellite for outdoor coverage, integrated with terrestrial repeaters (low power gap-fillers) for indoor coverage, especially in urban areas. The downlink - at the first stage from existing satellites to 3G infrastructure - is to operate in S-band (in the first tests - 2.2GHz).
Alcatel-Lucent performed a technical test of its solution for broadcast mobile TV. This pilot took place from June to September 2007 in the South-West part of France. There were used pre-commercial low-power terrestrial repeaters for the broadcast part, co-localized with several 3G operational sites. The broadcast signal from a satellite was emulated by a transmitter located in a high-altitude helicopter perceived as a fixed point. The mobile terminals used were pre-commercial terminals provided by Sagem and Samsung Electronics. The system was demonstrated at IFA 2007 in Berlin and IBC in Amsterdam (this month).

Mobile phone Samsung SCH - B540 with Digital Media Broadcast (S-DMB) capability - satellite/terrestrial system of mobile TV in Korea.

TV towers. These constructions are often higher than 300 m. At the very top of the tower there is usually mounted UHF transmitting antenna. The picture below shows the external elements of such antenna, made of glass fiber. The spiral holds the covering, protecting it against strong winds, suppressing vibrations, and strengthening the whole structure.
The antenna itself is placed inside the sheath, on a latticework, in the form of phase array of tens of reflectors facing all directions of the world. Such solution ensures omnidirectional characteristics of the antenna in horizontal plane and very narrow angle in vertical plane, which guarantees overall high gain of the array. The antenna is fed through coaxial cable with air dielectric, of over 20 cm diameter. Inside the cable there is a higher pressure (ca. 0.5 bar) than the atmospheric, which allows to monitor airtightness of the system and ensures resistance to humidity interference.

The tip of a TV tower.

Higher-class satellite receivers - GI-S770 CR Xpeed. Functionality of satellite receiver depends on its capability of signal processing. Many new features have been introduced in the GI-S770 CR Xpeed A99074.
The receiver has been equipped with hardware Component Video output (YPbPr), allowing better quality of the image displayed on LCD and plasma screens, and USB interface that can be used not only for updating the firmware, but also for playing/displaying MP3/JPEG files.
Instant Replay function enables the user to repeat the last 20-30 seconds of any broadcast. There is also possibility of watching two programs from one transponder simultaneously.
The receiver ensures automatic adjustment of the picture to the aspect ratio of TV screen (4:3 mixed oraz 16:9 mixed), considering different formats of broadcast channels.
This model has been equipped with universal card reader (CR), also compatible with SECA cards. For example, in Poland it is perfect choice for Cyfra+ subscribers who can directly put the smart card into the slot, check the validity term, and refresh (via satellite) their access rights for the next term.

Golden Interstar GI-S770 CR Xpeed A99074 - higher class DVB receiver.

Data compression algorithms used in IP cameras. IP cameras usually use M-JPEG and/or MPEG-4 compression. M-JPEG, due to its features, is used both in simple devices and high-end megapixel cameras.
MJPEG is based on compression of full frames, which ensures better quality when they are used for further processing, usually enlargement of the picture - so useful in the case of high-resolution cameras.
But most of modern IP cameras employ MPEG-4 - perfectly adapted for video transmission, due to high compression ratio that allows more effective use of existing network infrastructure.
Popular versions of MPEG-4 compression currently used in IP cameras are: MPEG-4 SP, MPEG-4 ASP (Advanced Simple Profile), and MPEG-4 AVC (Advanced Video Coding) also known as H.264.
The most popular version used in professional equipment is currently MPEG-4 ASP, but experts forecast that the winner will be MPEG-4 AVC. This variation requires advanced and powerful processor, so it is taking the first steps on the open market.
ACTi cameras using MPEG-4 ASP compression

AI lens - how is it built and how does it work? - Part 3. Control system of the actuator driving iris blades in AI lens.
Last week we described the electromagnetic actuator that drives the blades of the iris. Now we will analyze the control system.
The lens of switched-off camera has completely closed iris. After turning on, low-level video causes opening the lens (through amplifier connected with "Drive" coil). Speed of the opening is limited by negative feedback loop with "Damp" coil. Typical resistance of the Drive coil is about 200 ohm, and the Damp coil 500 - 1000 ohm. The feedback loop is controlled by voltage induced in the Damp coil (several millivolts) and amplified by dedicated electronic circuitry.

For that purpose there are usually used popular double operational amplifiers put into one DIL package. The equilibrium level can be changed with Level pot available in each camera prepared for work with DC iris lens.
When video signal increases (due to stronger light), the iris is closing, but the reaction also proceeds smoothly due to negative feedback.

Block diagram of the camera circuitry controlling DC Iris lens.

Next week - some information on Video Iris control.

Remote video monitoring of offices. IP transmission allows quite new approach to transmission of video data. It is no problem to build monitoring system of e.g. office, which will provide remote access to its resources. ACTi Corp., well known of its IP cameras, developed software that enables the user to have access (via a PC) to the streaming server - Streaming Activator and Streaming Explorer. The next application (Mobile Explorer) allows the same in the case of mobile devices like Pocket PC. This way, professional monitoring system based on ACTi devices and software (NVR program) is capable of local high-quality recording and simultaneous transmission of video suitable for remote and/or moving clients.
NVR utility enables the administrator to create individual recording schedule, motion detection options, user accounts and access levels, and to assign recording discs. There is possibility of monitoring available disc space of the server, searching and playing back the recorded material. Changes in configuration and viewing of archives can be executed both locally and via the Internet.
Very useful feature of the utility is support of different transmission speeds of live and recorded images, as well as two-monitor operation.
NVR supporting 16 channels is a free supplement to ACTi cameras.
NVR 32 K3032 is advanced software pack for 32 IP cameras, which allows to control larger monitoring systems.

Monitoring of parking lots, sport facilities and schools - vandal-proof IP camera Pixord P412. IP camera Pixord P412 K1331 has been equipped with vandal-proof and watertight housing. It is perfect device for using in all places where there is a risk of malicious actions. Due to built-in IR illuminator, the camera can be used in every lighting conditions (it is a day/night camera).
The camera uses 540 TVL image sensor. It generates images that can be displayed in Full D1 resolution (PAL: 720x576 pixels), at 25 fps. P412 may send MJPEG or MPEG-4 compressed video. The built-in SD card interface allows to record still pictures or video (AVI format) after motion detection has been triggered. The recordings can also be sent to FTP server and to assigned email address (as email attachment - also the AVI files). The camera has been equipped with NVR P6032 software pack that allows to control (viewing and recording) up to 32 IP PiXORD cameras.

IP camera Pixord P412 K1331

Video monitoring of schools. Vandal-proof dome cameras are the most often used indoor cameras in schools. An example is the camera C-3844-01A1 M10735. The metal housing plus polycarbonate dome cover and housing lock make this camera extremely resistant to vandals and hooligans, as well as accidental events like hitting with a ball. Additional feature of the device is dimmed dome that makes it difficult to notice the field of observation. The camera can be mounted on the ceiling or wall (with M5110 bracket). There is no problem with cleaning - it is enough to wipe the dome once in a while.
The preferred by installers outdoor camera is the model SN-468C M11202. It is high-sensitivity day/night camera. Due to IR operation it provides quality images in any lighting conditions. Choosing the camera one needs to remember about proper lens with auto iris, specially prepared for cooperation with IR illuminators (e.g. M2136), and outdoor housing with thermostat and heater. Having in mind security of the students and reliability of the system, in schools there should be used housings and brackets with concealed cables, and 12 VDC supplying voltage.
Video surveillance in schools

It is necessary to use housings and brackets with concealed cables.

New ADSL router - TP-Link TD-8841 N2908. The router TP-Link TD-8841 enables the user to share Internet connection provided as ADSL service (Annex A) among a number of computers. It has been equipped with built-in ADSL modem compatible with ADSL/ADSL2/ADSL2+, 4-port switch, and USB port. The WAN port is simply RJ11 connector that is linked directly to the phone line.
The device can operate as DHCP server.

The diagram showing possibilities of connecting ADSL router TP-Link TD-8841 N2908. The device enables the user to share Internet connection provided as ADSL service (Annex A) and create local network.

Honorable mention for the router TP-Link TL-WR642G N2953. Independent British PC World magazine has awarded TP-Link products. The router TL-WR642G N2953 was the device that specially drew attention of the editorial staff, for its low price and advanced features within its category, winning "Best Budget Buy" competition. According to the PC Word staff, TL-WR642G N2953 during the tests proofed that the declared area was covered with good signal.
Dipol is a distributor of TP-Link family in Poland.

Example applications of TP-Link devices based on eXtended Range 108 Mbps WLAN router TL-WR642G N2953 with 4-port switch.

Engagingly about Antennas - VI Summer 2007 DIPOL Competition is closing in a week - the entries.

"The fitter's imagination" - Miroslaw Sikora

Exhibitions and trade fairs. We invite those who cannot arrive in Poland at SatKrak in Krakow (18-20 Oct 2007) and Alarm in Kielce (8-10 Nov 2007) to visit our virtual stand.