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

Forgot the key? Your wife will send it to you by email!

At CeBIT 2013 in Germany, the Fraunhofer Institute for Secure Information Technology (SIT) presented "Key2Share" - a system that can turn smartphones equipped with NFC (Near Field Communication) modules into door openers and immobilizers. The access rights can be sent electronically.

The digital keys are issued by Key2Share server and then sent to the users' smartphone registered in the system. The access rights can be shared with other registered people: family members, friends, colleagues, just by sending QR codes attached to emails or MMSes, for opening specific locks. In addition to sharing the keys between users, it is possible to impose temporary restrictions on the use of them, which further expands the range of applications of this new system.

Presentation of the Key2Share system (in German)

The transmitted QR code is authenticated by the central server and authorized by user name and password in the application installed on the user's phone. This protects the code against the unauthorized use. The process of opening the lock is triggered by bringing closer the NFC device to the reader that also verifies the authenticity of the code.

Aside from private use, Key2Share can be applied wherever people share access to rooms or enclosed areas such as hotel rooms, offices, car parks, etc. The Fraunhofer solution allows fast and very easy distribution of the digital keys and quick blockade e.g. when a smartphone is lost. The Key2Share system is currently supported by phones running Android. Versions for other mobile operating systems are expected soon.

Fiber optic mechanical splicing - how does it work?

One model of mechanical splice can be used for different types of optical fibers whereas mechanical connectors are intended only for specific fibers.

Cross section of an SC/UPC mechanical connector:
1 - single-mode fiber optic cable, 2 - 125 um fiber placed in V-groove,
3 - optical gel compensating the effects of an imprecise cut and vibrations,
4 - built-in fiber fragment (dedicated for specific fiber type)

The working principle of the mechanical connectors is very simple. The ferrule contains a fragment of fiber suitable for the type of the connector and optical cable. There are mechanical connectors for OM1, OM2 (multimode) and SM (single-mode) cables. Additionally, single-mode cables can be terminated with UPC or APC connectors.

The use of mechanical connectors is the cheapest and easiest way of terminating optical cables. Mechanical connectors are used in optical distribution frames and boxes inside buildings.

KeyQuick mechanical splices and connectors are 100% compatible with international standards IEC 61753-1 and Telcordia GR-326.

Modernization of a shared antenna system.

A large housing association has decided to upgrade the antenna system in residential buildings. The works included the removal of the old equipment for reception of analog TV and deployment of a modern system to receive and distribute digital DVB-T broadcasts and satellite signals from Hotbird and Astra.

The realization of the task began with the installation of a new system in three-story building with four staicases and 36 apartments, each with two outlets. As the first thing, the contractor had to choose the suitable RF cables. Due to the very low attenuation and high shielding effectiveness, the choice for indoor cable was TRISET PROFI E1010, and for outdoor cable (between antennas and the in-building equipment) - TRISET-113 PE E1017.

The satellite DVB-S/S2 signals and terrestrial DVB-T broadcasts are distributed via a multiswitch system based on TERRA MSV-912 R70862 devices.

SMATV system designed with the use of free TERRA SatNet utility.
The video shows the procedure of designing a TERRA multiswitch system.

The system in the building has been based on MSV-912 R70862 multiswitches and SS904 R70523 splitters located on each floor in each staircase. Due to short distances between the multiswitches, there was no need for taps with graded attenuation, as the minor differences in signal levels resulting from the different lengths of cables could be compensated by the multiswitches. The SatNet utility enabled the designer to verify all settings at the developing stage. The designer assumed that each of the multiswitches would be powered via H signal lines from the broadband amplifier Terra SA-901 R70901.

The important thing is the application of two double channel amplifiers Terra at420 R82510 powered with DR-60-12 R82532 power supply (all modules have been mounted on R82538 rail). The set connected at the input of terrestrial TV path can amplify up to 4 terrestrial TV multiplexes, ensuring high and stabilized level of the broadcasts (AGC) for further distribution in the multiswitch network.

Sharp images in CCTV systems - the depth of field.

To draw attention of the viewers, photographers and cinematographers often use small DOF, also called shallow focus. This way they can emphasize the subject while downgrading the background or even the foreground. In contrast, for the owners CCTV systems it is desirable to have the entire image sharp, and a large DOF is a must.

Depth of field determines the distance between the nearest and farthest objects in a scene that appear acceptably sharp in the image. Assuming that the lens has relevant parameters (its resolution is compliant with the resolution of the camera), the depth of field can be calculated using the following formula:

where:
DOF – depth of field [mm]
N – F-number of the lens opening (iris)
f – focal length of the lens [mm]
s – the distance at which the lens is focused [mm]
c – the circle of confusion for a given image format, it can be assumed 0.005 mm for 1/3" image sensor

According to the formula given above, the depth of field depends on:

• iris diaphragm – the higher value the smaller the opening (aperture) through which the light enters and the greater the depth of field is (linear dependence),
• the distance at which the lens is focused (the distance between the "sharpest" object and the lens) – the shorter distance the smaller depth of field (quadratic dependence),
• focal length (quadratic dependence).

To summarize: in order to get the entire image sharp, the installer should use a high diaphragm (small aperture) and lens with the shortest possible focal length. So, if the field of view is too wide, the camera should be located closer to the monitored object(s). If the small aperture results in a dark image, it is better to use a camera with a more sensitive image sensor, or switch it to B/W mode, where applicable.

"Smart search" function in Hikvision DVRs.

The DS-7204HVI-SV M72104, M72108 and M72116 DVRs from renowned Hikvision manufacturer allow users to quickly browse the recordings for finding the moments that have been connected with some category of events. "Smart search" function is used to search for movement within a defined part of the camera image, which allows e.g. for finding the moment of theft or other offense. The clip can be exported onto an external storage and provided to police or security services.

New HIKVISION DVR from the DS-72xxHVI-SV WD1 series (976 x 582 pix)

Other key advantages of the new M72104, M72108 and M72116 DVRs include support for IE, Google Chrome, Opera, Safari web browsers and maximum recording resolution achievable in analog CCTV systems - WD1 (960 x 576 px), allowing for capturing the full detail provided by 650 TVL cameras (700 TVL in B/W mode) equipped with 976 x 582 px image sensors. Standard 4CIF DVRs with resolution of 704 x 576 pixels are not able to make full use of the increased resolution of the 650 TVL cameras.

Multipurpose wireless-N router.

The modem router TP-Link TD-W8968N N2909 has been designed for sharing Internet connection provided by Ethernet WAN (EWAN) or ADSL line. It has IEEE802.11n/b/g Access Point (transmission speed up to 300 Mbps), Fast Ethernet switch, multifunctional USB port.

Wireless-N Router TP-LINK TD-W8968N (ADSL2+, EWAN)
N2909

The USB 2.0 port allows for sharing a printer or local storage, as well as can provide access to the files via the Internet, using the built-in ftp server option. The users can also share music, videos, and pictures with the built-in media server. In addition, the embedded print server makes it easy to use a network printer at home or in the office.

Typical applications of the N2909 wireless modem router

Fiber-optic revolution and digital TV in a hospital. The designer of telecommunication system in one of Polish hospitals decided to implement a modern fiber-optic system, reducing copper wiring to a minimum. The project included application of the equipment offered by DIPOL... more

The architecture of the digital TV system in the hospital,
based on Terra devices and Ultimode BS-12 L7712 easy access cable

Reception of CATV/DVB-C on several TVs. The home distribution of digital channels (DVB-C) provided by a CATV operator can be based on typical passive splitters, e.g. R60102 (two televisions) or R60103 (three televisions). The DVB-C channels are usually encoded, so each TV has to cooperate with appropriate set-top-box (decoder), sometimes with the subscriber card. It is usually connected with an extra "multiroom" fee. The problem can be omitted if the CATV service includes analog channels and the programming is satisfactory for the users of the additional TV(s)... more

Splitting a cable TV line with the Internet

How to transmit video from several analog cameras via a single coaxial cable? An installer had to send signals from additional three security cameras, but he could use only one existing coaxial cable. There was no permission to install any additional cables... more

Diagram of a CCTV system using RF modulators to transmit video from 4 analog cameras via a single coax.
The images can be watched on any TV and recorded on the DVR after demodulation of the RF channels.