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

No. 35/2009 (Oct. 26, 2009)
TERRA - F1 among multiswitches. At SatKrak exhibition there were granted annual awards for the best products of the year. The voting included the votes of Internet users. This year, the Best Product in multiswitch category became the TERRA line of radial multiswitches.
TERRA multiswitches are professional-grade products. They are designed for large and complex installations in housing developments as well as for demanding individual users (in larger one-family houses and other buildings). Due to high quality, reliability, easy installation and maintenance-free operation, they are really great products. The multiswitches are widely used in SMATV systems up to 1000 outlets!

Distinguishing features:
  • best on the market and stable modulation error rate (MER) for SAT signals,
  • excellent isolation between inputs and between outputs (min. 30 dB, typ. 45 dB),
  • flexible power options - versions with built-in power supply or for supplying from a central power supply,
  • low power consumption does not generate much heat, which extends the life of the equipment,
  • the manufacturer offers a free SatNet program that allows to design more complex installations.
TERRA - F1 among multiswitches
How we have built F1 car out of TERRA multiswitches
What does the TERRA multiswitch offer include?
DIPOL sells full range of the multiswitches, both for cascadable and radial solutions. They allow to receive broadcasts from 1, 2, 3, or four satellites. There are available passive and active models, with local or remote power supply. With the use of additional equipment we offer (splitters), the designers can create advanced and flexible multipoint SMATV systems.
2009 Nobel Prize in physics for the invention of the CCD. The Royal Swedish Academy of Sciences awarded this year's Nobel Prize in physics to three people, among them to Willard Sterling Boyle and George Elwood Smith from the U.S. - "for the invention of an imaging semiconductor circuit - the CCD sensor".
Scientific world of the nineteen sixties sought a new way of recording images for use in astronomy, to observe the cosmos. It was achieved in 1969, when this year's Nobel Prize winners, working at the Bell Telephone Laboratories, built the first charge-coupled device (CCD), participating in a video phone project.
The first device had only 9 elements arranged in a row and could not detect light. It was a miniature set of capacitors (along the surface of a semiconductor) connected in such a way that it was possible to move the charge accumulated in a single element (bin) to one of its neighbors, and then convert the electric charge at the end of the chain to electrical voltage easily convertible into a digital value.
CCD had been originally conceived as a memory device, but the researchers shortly realized that, via the photoelectric effect, electronic images could be created, which they published in the following year. Since then Bell researchers were able to capture images with simple linear devices.
Fairchild was the first company which developed commercial CCD devices in 1974 (a linear 500-element device and a 2-D 100 x 100 pixel matrix).
Typical CCD sensor architecture (source: micro.magnet.fsu.edu)
Today, CCD technology is used wherever there is a need to capture images. It is especially useful in digital photography, video cameras, telescopes (astronomy), and CCTV cameras. CCTV CCD cameras are the main group used in video surveillance, despite the fact that CMOS-type imagers were invented earlier. For years CCD sensors offered higher quality and better visualization of details. Nowadays practically all analog cameras and IP cameras with standard resolution are still equipped with CCD sensors.
Megapixel cameras usually employ CMOS sensors, however, due to continuous development of CCD technology, the proportion can be changed - at this year's IFSEC exhibition in Birmingham megapixel cameras with CCD image sensors were presented by the most renowned high-tech companies.
The image sensors used in CCTV are characterized by resolutions of up to several megapixels, but special devices for astronomical research can reach up to 100 Mpx.
CCD sensor in a modern camera
The Pearl River Tower. Construction of the television tower, visible in the pictures below, is not yet complete. After putting into service, it will be 610 meters high, being the highest tower and the second highest free-standing building in the world (after Burj Dubai). The unique hyperboloid shape makes it one of the nicest buildings in the world of high-rise architecture. Perhaps will never be built television tower higher than this one (currently in Tokyo is being built a tower of identical height).
The highest television towers are built in vast countries with a relatively low population density (Russia, Canada, Kazakhstan, some regions of China). The change in technology - digitalization of broadcasting - will allow to use lower, cheaper and less powerful transmitters.
Where is the world's highest TV tower? - The answer at the end of this issue.
After putting into service, it will be 610 meters high, being the highest tower in the world.
Where is the tower? The answer at the end of this issue.
MAC layer - a few words on WiFi - part 9. The station which wants to start a transmission must first check whether the channel is free, if so, after the DIFS time it begins the transmission. If not (the channel is busy), the station must wait until the end of that broadcast, and then it randomly generates access time delay TB, after which it can restart transmission. The TB period is given by the formula:
TB = Random(0, CW)*slot length
    - TB - is expressed in the number of slots
    - slot length - is a constant characteristic for a specific physical layer. The slot length includes the maximum propagation delay, switching time of the transmitter and the time needed for checking whether the channel is free or not.
    - Random(0, CW) - randomly generated integer from the (0, CW) interval. CW - Contention Window - a number from CWmin , CWmax interval. CWmin and CWmax are constants characteristic for specific physical layers (e.g. for 802.11a: CWmin = 15, CWmax = 1023, for 802.11b: CWmin = 31, CWmax = 1023).
The initial width of Contention Window is set to the minimum value of CWmin; each unsuccessful transmission (packet loss, collisions) increase the CW in accordance with the relationship: 2*CW-1, up to CWmax. The value is reset to CWmin after correct transmission.
The algorithm selecting TB is known as BEB (Binary Exponential Back-off).
If during the decrementation (decrease) of the back-off counter the channel is busy, it means that the counter of another station has been cleared. In such a situation the other stations stop their counters and wait for another period of silence in the channel, for DIFS time. If it occurs, the stations continue to decrement their counters. The station of which the counter first resets, has the access to the transmission medium. If, at the same time, two or more stations have reseted their counters, they all simultaneously start broadcasting and their frames collide with each other. Then, each of these stations increases its CW value and generates a new TB period, which reduces the likelihood of subsequent collisions.
In the next part we'll continue the description of the algorithm of access to the medium.
Antennas for receiving digital terrestrial television. It is well known that the reception of DVB-T signals is possible with antennas designed for analog TV. However, it is worth mentioning that DVB-T multiplexes can be distributed even on channel 69 (the end of the UHF band), while most of the antennas currently used have been designed for channels 21-60.

Antennas working up to 69 channel
UHF TV Antenna: DIPOL 16/21-69 DVB-T
UHF TV antenna: DIPOL 19/21-69 DIGITAL
UHF TV Antenna: DIPOL 44/21-69 Tri Digit
UHF TV Antenna
DIPOL 16/21-69 DVB-T
UHF TV Antenna
DIPOL 19/21-69
UHF TV Antenna
DIPOL 44/21-69 Tri Digit
ULTIMODE optical adapters. The adapters allow to connect optical cables terminated with optical connectors. Adapters are usually used in combination with patchcords and pigtails in optical concentrators etc.

The offered adapters can be distinguished due to:
Multimode Adapter ULTIMODE A-011S (SC to SC)Multimode Adapter ULTIMODE A-011S (SC to SC)
Single-mode Adapter ULTIMODE A-511S (SC to SC)Single-mode Adapter ULTIMODE A-511S (SC to SC)
Multimode adapter (SC to SC)
Single-mode Adapter (SC to SC)
Playing back recordings from CCTV DVRs on different devices. A frequent problem associated with the use of recorded images as evidence is no possibility of playing them on universal devices (e.g. PCs).
ULTIMAX recorders, similarly to majority of DVRs, allow to copy the recorded material. However, the special feature of ULTIMAX series is that all recordings can be transferred in original, unchanged form. When copied, the files are not re-compressed and keep the original format (mp4 extension). Therefore, any copy retains all the characteristics of the original. The quality of playback material depends only on the pre-configured parameters of the recording.
The recordings can be played with Windows Media Player, after installing on the computer filters available in our Download section.
12 questions for those who plan to build CCTV installation - part 2. In the previous issue we have presented 12 questions which should be answered by the investor along with the designer of the system before starting the project. There have been outlined the main categories of CCTV systems that depend on general objectives of the undertaking.

The next step in the specification of a CCTV system is defining the monitored areas and the surveillance aims.
2. Which areas are going to be monitored?
After going on an on-site visit it is needed to point out on the map of the place the areas that should be monitored. This allows the designer to choose the number of cameras and their placement, and then to specify the size of each monitored area by selecting the appropriate lenses.
CCTV Lens: Tokina 2.7-12.5 mm F1.4 DC A/I
CCTV Lens: Tokina 6-60 mm  F1.6 DC
CCTV Lens: Tokina 10-120 mm  F1.6 DC A/I
Tokina lenses: 2.7 - 12.5 mm, 6 - 60 mm, 10 - 120 mm
3. What are the aims of monitoring individual areas?
How the recorded material will be used? Is a specific camera going to provide only a general view of the area, or perhaps it is necessary to identify the passing people? Since there is no standard solution for each camera point, it should be decided individually according to specific requirements. In some cases the optimum solution is application of a megapixel camera, in others the purpose of the camera point is accomplished by using a standard device. Therefore, to get the best results, the system usually will combine the both kinds of cameras. Advanced features of some cameras will allow to utilize predefined alarm procedures.
IP Day/Night Camera: ACTi ACM-5711
IP Camera ULTICAM DS-852MF-E (2.0 Mpix)
IP Speed Dome Day/Night Camera: ACTi CAM-6621 (MPEG-4)
Fixed D1 camera
for general monitoring
Megapixel camera
for detailed monitoring
Speed dome camera
for large area monitoring
Backup link using ULTIAIR devices. Reliability of connection is one of the basic requirements for transmission systems. The most common reason for loss of communication is the failure of radio modules caused by electrical discharges. The solution to such a problem is a wired or wireless backup link which is activated when the main connection fails.
Ideal equipment for creating wireless backup links are ULTIAIR devices equipped with RouterBords run by Mikrotik system. The devices support OSPF protocol (Open Shortest Path First), whereby in the event of problems with the main link, the transmission will be continued by backup link.
Wireless Access Point: ULTIAIR 423KCWireless Access Point: ULTIAIR 423KCWireless Access Point: ULTIAIR 323KCWireless Access Point: ULTIAIR 323KCRouterBoard 433 (MikroTik license level 4)RouterBoard 433 (MikroTik license level 4)
Transmission via the main link
RouterBoard 433 (MikroTik license level 4)RouterBoard 433 (MikroTik license level 4)Wireless Access Point: ULTIAIR 423KCWireless Access Point: ULTIAIR 423KCWireless Access Point: ULTIAIR 323KCWireless Access Point: ULTIAIR 323KC
Transmission over backup link
The N24334 devices are responsible for re-routing in case of loss of transmission on the main connection. N2301 and N2311 devices are responsible for wireless transmission of the data.
In principle, backup links should use different transmission medium than the main links. Usually wireless link provides backup of a cable line, such as fiber optic line.
It is worth to pay attention to parameters of WLAN connectors. The role of the connector as the element of transmission line is often underestimate. Low quality connector crimped on even top-class cable can totally destabilize the operation of the link.

There are two most important parameters of RF connectors:
  • Voltage standing wave ratio (VSWR) indicating how much of the power of the signal is reflected back to the source of signal. The parameter should not exceed 1.5 (which means that ca. 4% of the signal's power comes back to the source).
  • Insertion loss indicating loss of power inside the connector. This parameter should not exceed 0.2 dB.
If the seller does not specify the parameters of the connectors sold, there is a high risk that they do not meet the relevant criteria, which may cause problems during the installation and operation.

N-plug for Tri-Lan 240/H-155 cable (6 GHz)
N-socket for Tri-Lan 240/H-155 cable (6 GHz)
TNC Male/Plug for Tri-Lan 240/H-155 Cable (6 GHz)
SMA/RP male connector for Tri-Lan 240/H-155 cable (6 GHz)
SMA/RP female connector for Tri-Lan 240/H-155 cable (6 GHz)
N-plug for
Tri-Lan 240/H-155
N-socket for
Tri-Lan 240/H-155
TNC Male/Plug for
Tri-Lan 240/H-155
SMA/RP male
for Tri-Lan 240/H-155
SMA/RP female
for Tri-Lan 240/H-155
The connectors used outdoors have to be protected against penetration of water. It is so important because even a drop of water would increase VSWR even by several tens of percent, changing energy of the signal into heat. For that purpose we recommend to use special self-amalgamating SCAPA tape.

Guangzhou (Canton). Large city in the southern part of the People's Republic of China. Population of the city amounts to about 5 million, and three times more in the whole urban area.
Since 1957, China's export offer is presented at the China Export Commodities Fair, popularly known as Canton Fair - the world's largest fair event. It is a meeting of representatives of Chinese entrepreneurs with their partners and vendors from around the world. The fair is held two times a year, in spring and fall, and lasts two weeks. Currently, the 106th edition is planned.
In addition to the television tower and the China Export Commodities Fair, Guangzhou is renowned for its market of traditional Chinese medicine. In the pictures: seahorses, snakes and scorpions.
We have written about:

Focus hotel chain modernizes TV antenna systems. Important sports events can motivate hotel management to improve the quality of TV reception. Before Beijing 2008 Olympics, for the comfort of the guests, Focus hotel chain decided to increase the number of received programs and their quality...
- archive DWR of Sept. 1, 2008
TERRA headend and set of ZG channel amplifiers installed in Hotel Focus
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

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

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