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

Martian eyes.

The Curiosity Mars rover has been equipped with a set of 10 instruments which make up a highly specialized geological and meteorological laboratory. The eyes are 17 cameras with CCD sensors, five of them used to conduct scientific experiments and twelve to navigate the vehicle.

The key instruments on the Curiosity rover

MastCam is a set of two color cameras with a resolution of 1600 × 1200 pixels, each equipped with a CCD sensor and RGGB Bayer pattern filter. The cameras are identical, but they use different lenses (one lens with a focal length of 34 mm, f / 8, the second 100 mm, f/10). They can capture video and take pictures (including panoramic ones), as well as enable multi-spectral analysis - in the visible light, far- and near-infrared and ultraviolet ranges. For this purpose, each camera has an eight-position filter wheel, in the range from 440 to 1035 nm, and ND filter (gray), to capture Sun images. Each MastCam camera is equipped with 8 GB of internal memory to save photos and videos (buffer). First, each photo is sent to the Earth as a miniature (in size of 200 x 150 pixels) to allow NASA scientists to determine whether it should be transmitted in full resolution. The cameras were manufactured by Malin Space Science Systems.

The MastCam camera

Mars Hand Lens Imager (MAHLI) is a color camera with a resolution of 1600 × 1200 pixels, equipped with a zoom lens (18.3 - 21.3 mm). It is mainly used to acquire microscopic images of rock and soil, but can also examine the rover components. The device is placed on the rover's robotic arm. It can take macro pictures from the close focus of 22.5 mm, perform z-stacking and 3D imaging. MAHLI is supported by 6 LEDs, two of them emitting ultraviolet light at the wavelength of 365 nm, suitable for search for fluorescent minerals. The camera was produced by Malin Space Science Systems.

The MAHLI camera head

Mars Descent Imager (MARDI) - color camera for capturing images in the landing phase with a resolution of 1600 × 1200 pixels. The task of MARDI was to take about 500 pictures during the period of about the last 100 seconds before the touching the surface of Mars. As planned, the camera began to work at a height of less than 3.7 km, and the last pictures were taken ​​from about 5 meters above the surface. The pictures taken by MARDI would help researchers map the terrain surrounding the location of landing and precisely plan the rover's route. The camera was also produced by Malin Space Science Systems.

Mars Descent Imager

ChemCam - a set of devices for remote detection of chemical composition and for high-resolution imaging of the sampling areas. ChemCam consists of infrared laser that emits in the direction of a selected sample (a rock or soil, over a distance up to 7 m) a series of 5 ns laser pulses with power of over million watts and a camera analyzing the image. The vaporized material forms a ball of luminous plasma, the image of which is analyzed by spectrometer determining the chemical composition of the sample. ChemCam can analyze 6144 different wavelengths - from ultraviolet (240 nm) to infrared (800 nm). ChemCam is a joint effort of U.S. and French scientists.

ChemCam components

In addition, Curiosity has been equipped with 12 black-and-white cameras with a resolution of 1024 × 1024 pixels, which serve as the "eyes" for the rover to identify and avoid obstacles.

Curiosity communicates with Earth using one of three antennas. The primary communication system operates in the UHF band (the same which is used by common television systems) and connects with Mars orbiters, including Mars Reconnaissance Orbiter (data rates 2 Mbps or 256 kbps, the maximum transmission window of 15 minutes). In turn, the orbiters relay the data to a special network of antennas on Earth.
The other systems use X-band (about 8 GHz) with two antennas capable of direct transmission to Earth. One of them is a low-gain antenna for low-rate communication (15 bps), the second allows for data rate of 32 kbps, but it has to be unfolded. The communication in the X-band is possible around the clock.

Communications links with the Earth

"Engagingly about Antennas" - 11th edition.

The current edition will continue until September 30.
The rules of the competition and the pictures sent so far
We invite everyone to participate!

How to power cameras via coaxial cable at distances up to 800 meters.

Supplying power for 12 VDC cameras over distances greater than 50 meters has always been one of the major problems faced by CCTV installers. While the video transmission over a few hundred meters is no obstacle, DC power supply is possible at a relatively short distances, especially with typical cables having cross section up to 1 mm².

The issue has been definitively resolved by PoC-P201 M16201 video and power transmitter/receiver sets. The set is used to power a security camera with 12 VDC voltage (max load 1 A) and transmit/receive the composite video signal over the same 75 ohm coaxial cable (RG-59 or higher quality) at a distance up to 800 m. The maximum distance of 800 m has been reached with the use of Camset and Triset-113 cables.

Typical application of the PoC-P201 M16201 set in a CCTV system

The ready-to-use kit includes AC/DC adapter (230 VAC / 36 VDC).
There is a 4-channel version - Etrix PoC P-204 M16204.

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.

The use of optical fibers not only eliminated problems typical for copper systems (stray currents, risks from voltage surges, mutual interference with specialized medical equipment) but also made it easier to design the whole system.

The investor required to supply digital TV signals to each patient's bed - DVB-T channels and selected broadcasts from Hotbird satellites.

The DVB-T multiplexes amplified and equalized by Terra at420 R82510 amplifiers have been combined with additional, internal DVB-T multiplex composed of some satellite channels converted into this standard by MMH-3000 headend. The application of three RDC-311 R817102 modules and one TRX-360 R81709 module enables reception and distribution of 8 satellite SD channels from 3 transponders. The combined RF signals are fed to the high-power optical transmitter MOS-211 R81720, and further distributed in the optical form trough Ultimode IDC-4 SM L7504 cables to floor splitters and FTTH nodes TERRA OD-003.

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

For this purpose, the most suitable optical cable was Ultimode BS easy access cable. ULTIMODE BS-xxSM cables make an innovative system for fiber optic cabling in buildings, based on easy access concept. The fibers can be branched directly to individual nodes without the need for splicing at each branching point. They are easily extracted from breaking windows in the gel-free tube. Using this cabling, all optical splitters could be placed in technical rooms located at the entrance areas to three floors. Each pair of rooms with a total of 6 beds has been equipped with optical node TERRA OD-003 R81728. Within each hospital room the output RF signal is fed to TV outlets via copper coaxial cable.

The designer also considered the use of Ultimode BS-24 SM L7724 cable that would allow for running individual optical fiber to each bed for diagnostic purposes (transmission of data from various medical equipment).

The designed system complies with the requirements of the investor. It can be easily modernized in the future by exchanging only the terminal devices - the optical cabling will be a modern platform for years.

Operating and half-power angles of IR illuminators.

Half-power angle is the angle within which radiation intensity of the beam does not fall below 50% (3 dB) below the maximum value. The smaller the half power angle, the higher concentration of the beam. Operating angle is larger, in the case of Redbeam illuminators equipped with lenses it is about twice as wide as the half power angle.

Basic specs of Readbeam illuminators:

Managed PoE switch from TP-LINK.

Managed TP-LINK switches are powerful network devices with extensive set of management tools. With easy access to configuration functions, network traffic control becomes much simpler than before. Available management options include: command-line interface (CLI), telnet sessions, SNMP, management via web browser. These managed gigabit switches provide very high stability and efficiency of operations - the basic features required by network administrators. Reliable operation of the network is also supported by spanning tree protocol, QoS and robust security features. In the case of TP-LINK TL-SG3424P N29961 switch, all Ethernet ports support 802.3at/af standard (PoE) - they can provide power to the connected network devices.

An application of the TL-SG3424P N29961 switch in IP CCTV system

A multiswitch system with over 300 outlets and convenient form of power supply. The installation in the building with two wings should distribute signal to nearly 350 outlets.
Taking into account esthetic requirements, the designer should use only one antenna array. To design the system capable of receiving channels from two satellite positions, using SatNet design tool, he chose line amplifiers for 9-input multiswitches SA-901 R70901, 9-input multiswitches from MSV-9xx series with different numbers of outputs, suitable for bus-topology systems, as well as splitters and taps of SS-9xx series (available with different attenuation levels).
When carrying out such projects, the designer has to take into account not only appropriate signal levels in all outlets... more

The SMATV system with about 350 outlets

DVR with a passive cooling system. The ATU M71000 DVR may be an optimum choice for users looking for a compromise between high quality and low price. This compact device provides high computing power sufficient for recording 4CIF images at 12 fps. The frame rate can be increased up to 25 fps in the case of recording 2CIF images. The DVR is ideal for video monitoring systems in homes (such a system has been described in detail in the article: Home CCTV systems), small businesses, shops etc. Despite its low price, the device supports the latest solutions for CCTV systems: H.264 compression, high-capacity SATA drive (up to 2 TB), remote monitoring over web and mobile phones... more

Atu DVR
M71000

Protecting wireless networks from lightning. In a way, many antennas protect the cooperating transceivers (APs) against atmospheric discharges. These antennas are DC short-circuited. An example is A741030.
The level of lightning protection can be significantly improved by installing an RF surge protector between the antenna and AP or GSM repeater. The lightning protector must be grounded via the clamp and low-impedance wire. To avoid overvoltages, the protector should be connected to low-resistance grounding (below 4 ohm), by screwing or soldering. As the grounding... more

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