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No. 32/2022 (October 10, 2022)
How to build a camera for underwater observation?
Scientists at MIT have built a wireless and battery-free camera for observing marine environments. It is very energy efficient – it consumes 100,000 times less power than today's solutions and is able to transmit data wirelessly using water as a medium. At the same time, it is able to take and transmit color images even in dark depths.
The autonomous camera is powered and communicates via sound waves. The energy needed for operation is obtained by piezoelectric transducers. When a sound wave traveling through the water strikes the transducers they vibrate and convert mechanical energy into electricity. The sound waves can come from various sources such as natural sounds present in the marine environment or those from passing ships or from a special transmitter, also used for communication. The energy thus obtained, the camera accumulates in supercapacitors.
Diagram of the operation of the system for underwater transmission
The image sensor must consume a small amount of energy, so the researchers used off-the-shelf solutions that record grayscale images. In addition, for operation in the dark, they had to install a flash built of 3 LEDs: red, blue and green. The image is exposed by each of them in turn, and the resulting color image is possible after synthesizing the exposure data.
The greatest challenge, perhaps, is wireless communication. In water, most types of transmission are heavily attenuated, but sound waves work better than in air, achieving nearly five times the speed and much greater range. The sound wave used for power can be used for communication at the same time. When a camera absorbs sound, it means it is sending a zero, while wanting to transmit a one, it must reflect it. This creates a zero-one transmission system. Still needed is a hydrophone, which is a device for receiving sound in the water. Such a system minimizes the amount of energy needed for data transmission.
Exploration of the seas and oceans is still in its early stages. Scientists estimate that only 5 percent of the oceans have been explored. The biggest problem is the cost of conducting the research, much of which is related to the need to replace batteries in the cameras. The new camera solves these problems, but still needs work to increase its operating range. For now it is only 40 meters from the receiver. If they succeed in increasing it, the researchers plan to launch online streaming of images from the depths.
Measuring DVB-T2/C & DVB-S/S2 signals.
The proper alignment of a DVB-T2 terrestrial or DVB-S/S2 satellite TV antenna, which has a key impact on the quality of the received signal, usually requires a professional meter. It is the installer, assembling the antenna set, taking and interpreting the measurement, who is able to accurately correct the antenna settings in order to achieve trouble-free reception of DVB-T2 or DVB-S/S2 signals.DIPOL offers the combo meter ST-6986 ST-6986 measures DVB-S/DVB-S2 (HD) satellite signal, DVB-T/T2 (HD) terrestrial TV signal in HEVC 10 Bit compression and DVB-C cable signal.
The ST-6986 R10210 meter allows you to measure the most important parameters of DVB-T2/C television and DVB-S/S2 satellite television: signal level expressed in dBμV, C/N, MER.
The spectrum distribution analyzer, especially for terrestrial TV, allows you to view strong interfering LTE signals which can adversely affect the quality of DVB-T2 signal causing interference and interfering with proper reception of terrestrial digital TV.
Another advantage of the COMBO R10210 type meter is the built-in tuner that allows you to constantly view the channel you are setting, as well as the spectrum distribution analyzer. The monitoring of the tested channels and intuitive operation accelerate installation work. An unquestionable advantage of the device is a user-friendly menu, making easier the work of users without much experience in this field. In addition to that, an external HDMI output can feed the received channel to a TV/monitor screen via a cable.
How to power a camera and 12 V microphone using PoE?
Numerous systems are faced with the problem of powering an IP camera via PoE from one UTP cable and another device requiring 12 VDC supply (e.g. an external microphone or an infrared illuminator). This can be done with any PoE (802.3af or PASSIVE) switch and using one output and the PoE Atte ASDC-12-124-HS M18953 stabilizer. The device supplies power to the PoE output and has a 2.1/5.5 12 VDC plug. The maximum current at such output is 1 A at 12 V, however, the power limit available at the PoE output for the switch have to be considered while supplying both devices.How to choose the right GSM/LTE repeater?
The repeater is used to amplify GSM, DCS, 3G, LTE signal and bring it inside the premises. The repeater has to be connected with an external antenna, directed towards the base station of the operator, and to an internal antenna which will distribute the amplified signal.- The first important thing to know before purchasing a repeater is the type of band to be amplified:
- GSM, EGSM – this band is found in and outside the city. By amplifying this band, you can talk as well as transmit data (Internet) through the cellular network.
- DCS – this band is primarily found in the city due to the large capacity of the base station (large number of terminals to support).
- WCDMA (3G) – this band is found in the city and allows for high speed data transmission (mobile internet (HSDPA), video calling and other 3G services).
- LTE – this band allows for high speed data transmission (mobile internet (LTE), calling (VoLTE)).
- Another important information is the size of the area to be covered by the amplified signal:
- For the GSM signal:
- < 300 m2, then the Signal GSM-305 A6765 repeater is a suitable device,
- less than 1200 m2, the Signal GSM-1205 A6785 repeater is the right choice,
- In the case of GSM, DSC, 3G, LTE signals (Signal GDW-505 A6777), a device covering an area of 500 m2 with one internal antenna is available.
Example of a GSM repeater application
Control of relays in the IP Villa 2 gen. door/gate station with external buttons.
Video intercom door/gate stations IP Villa 2nd generation (except for DS-KV6113-WPE1(B) DS-KV6103-PE1(B)), have 2 independently triggered built-in relays, which enable the control of e.g. a wicket or an entrance gate. By default, the second relay in the door/gate station is off and should be activated with the iVMS-4200 app or via a web browser. Those outputs can be triggered using the iVMS-4200 PC client application, indoor stations or after shorting to ground (GND) of AIN4 (DOOR2 relay activation) and AIN3 (DOOR1 relay activation) inputs. Those inputs are often used for the installation of local opening buttons, mounted at a safe distance so that they cannot be reached from outside the fence. The solution can open the wicket without a key, if no movable handle or knob is installed on the inner side. The gate can open quickly without the need for a remote control.Connecting to local opening buttons to Villa door/gate stations
DS-KV8113-WME1(B), DS-KV8213-WME1(B), DS-KV8413-WME1(B)
DS-KV8113-WME1(B), DS-KV8213-WME1(B), DS-KV8413-WME1(B)
SmarT antennas vs. AGC circuit of channel amplifiers.
The use of terrestrial TV amplifiers in SMATV DVB-T2 and multswitch systems is required in virtually every installation regardless of its location. It is good practice to choose a channel amplifier as the first DVB-T2 signal amplification component. In addition to the basic task, i.e. adequate signal amplification (it does not necessarily have to be a very high level, often it is the right level to feed into the next device, such as a multiswitch), a channel amplifier allows you to equalize the level of all signals, which greatly facilitates further construction of the network. Another advantage of this type of amplifiers is the filtering of all unwanted frequencies received by the antenna set.Terra channel amplifiers: PA321TP R82513 and PA420T R82516 combine good signal processing performance, high functionality, speed and convenience of configuration, and affordable price, which is not the case with devices of this type. Like most modern channel amplifiers, Terra amplifiers are equipped with multi-stage Automatic Gain Control. Thanks to it, the amplifier generates a constant, stable signal at the output, regardless of fluctuations in the input signals.
An important feature of AGC systems is the range of signal levels in which they are able to operate correctly. In DVB-T2 systems, TERRA amplifiers require a minimum signal level of 50 dBμV. In the case of the competing solutions, these values can deviate significantly from the declared ones. Signal below 50 dBμV may be sufficient for reception, but it will not allow for proper control of the channel amplifier. In such a situation the solution is to change the antenna for a model with a higher gain (if possible) or to install an antenna preamplifier which will boost the signal level above the 50 dBμV required by the AGC system.
Therefore, the ideal option for channel amplifiers are antenna sets based on DIPOL SMART antennas. The HORIZON A2230 antenna, in addition to its high gain, has the ability to switch from passive to active mode when 12 VDC is applied to the antenna cable, e.g. from a channel amplifier or a power supply with an isolator.
You can read more about the interaction between DIPOL SMART series antennas and Terra channel amplifiers in this article.
 | MicroSDXC 256 GB UHS-I class 10 card + SD adapter M90379. The latest GOODRAM microSDHC cards use the capabilities of the UHS-I or Ultra High Speed interface. The implemented UHS-I interface will be perfect for high-definition recording and playback, or for live HD broadcasting. At the same time, GOODRAM microSDHC UHS-I card is backward compatible with devices that support the 2.0 working standard. In this case, the card will work with the minimum operating parameters corresponding to the 10th speed class (min.10 MBps). | |
 | 12 VDC 300 mA power adapter D0021 with power supply isolator in die-cast metal housing with F-type sockets, with a separator LED that indicates the device status. A switching power supply based on a single converter system with a very low power consumption in no-load condition. | |
 | The 38 mm/2 E9038201 m hot-dip galvanized steel antenna mast that can be combined /system A/ is designed in such a way that it can be combined into a larger whole. Thanks to special embossing on the ends of the mast, it is possible to combine the elements with the keyway system over a length of 12 cm by driving another segment in such a way that the embossing overlaps. After combining, it is not possible to disconnect the segments. | |
Worth reading
TerrNet application – fast and intuitive programming of TERRA channel amplifiers. The PA320TP R82513 and PA420T R82516 TERRA channel amplifier can be used standalone – as part of a multiswitch or headend system. TERRA amplifiers are dedicated to receive RF signals in difficult conditions. They will perform well in places where there are signals of varying levels, transmitted from one or several directions. Each of the 20 amplification paths is equipped with automatic gain control (AGC) and an ultra-selective SAW (Surface Acoustic Wave) filter. The PA320TP R82513 and PA420T R82516 TERRA channel amplifiers are programmed digitally, using any device...>>>more
SMART CITY DVB/T2 antenna with bypass up to 100 km from the transmitter
