Compact multi-function DVR

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    Today, the topic of video surveillance and telepresence is becoming more and more popular and in demand every day. At first glance, it seems that the market is filled with video recording, storage and processing products. However, if you want to install a simple, uncomplicated surveillance system in your apartment, in the house, in the country, or even in a car, or somewhere else, then looking in stores and on the Internet, you will understand that suitable products that meet the affordable price / price ratio (quality + features), quite a bit. What are the most popular characteristics that a DVR must have in order to be wanted to put on your site? Let's try to list them:

    • multiple video channels. Usually, about 4 video cameras are enough for a good overview of the apartment, or a section of a country house.
    • good video quality.
    • the ability to record all channels in realtime mode, i.e. minimum 25 frames / s per channel.
    • at least one audio channel.
    • availability of hard media for long-term storage.
    • the ability to remotely view video and control cameras via the Internet.
    • the presence of a USB port for quick connection of the device to a PC and copying information and other operations.
    • RS-232 / RS-485 ports.
    • small dimensions. Recorders the size of a DVD player or an old VCR are already considered quite bulky and are mostly suitable for installation in a surveillance point or checkpoint with a permanent operator, but not for home use. In addition, it is not convenient to store, as it takes up too much space.
    • the ability to connect from a 12 / 24V source for use in cars. The presence of surge protection up to several tens of volts, protection against reverse polarity, suppression of short-term surges.


    The above properties of the video recorder are basic. In addition to them, it would be nice to have an optional package that could be installed in the registrar at the request of the client without increasing the size, but for an additional fee. These optional properties may include:

    • the presence of a wireless module (GSM / 3G) for receiving alarm / emergency SMS messages or transmitting a video stream (or individual frames) to a mobile phone in the event of any event at the facility.
    • the presence of a Wi-Fi wireless module for interaction with any internal network, or for communicating with a device for displaying information on a display (tablet computer, iPhone, etc.).
    • the presence of a digital input / output module and CAN interface for connecting external sensors (for example, alarms, shock sensors, door open sensors, etc.) and for controlling external actuators using discrete signals (turn on the light, close the door, turn on the siren , etc.).




    Compact multi-function modular recorder


    Oversized video recording devices are currently appearing on the market, supporting part of what is listed above. Nevertheless, among the well-known, the most oversized 4-channel modular device that supports all of these features is likely to be the device HDRx4-v01 from ARMiSoft ( www.armisoft.net ).

    The device is in the production stage of the prototype. The main hardware and software parts of the device are tested on the debug board. The prototype will be assembled and tested by mid-December. Accessories have already been ordered, production of printed circuit boards has been launched. We hope that the prototype, after minor modifications and corrections, will go into series.

    The design of the product is modular, which will allow it to be modified for different designs and tasks. The device contains 3 boards: a microprocessor board, a power board, and a wireless card. This design makes it easier to implement the option, increases reliability, since the power board and power protection circuits (especially important for transport applications) are separated from the sensitive microprocessor board. Due to the modular development of software and hardware devices, rapid system modernization and repair will be provided if necessary.

    The device is designed to register on the 2.5 ”HDD a real-time audio and video data carrier simultaneously from four cameras, as well as to remotely view video and control external devices via communication interfaces.

    The use of the device is possible in transport, on mobile installations, at industrial facilities, in houses, apartments, shops, parking lots, etc. The main expectations are related to the residential sector - apartments, private houses. The presence of communication modules, as well as the external periphery, significantly increases the attractiveness of the device.

    The company plans the first series of finished devices in early 2014. The output coincides with the seasonal activity of the market.

    The purpose of writing this article is to attract interest in this registrar and in all products of the company. More convenient terms for pre-ordering devices are possible. Specific pre-order delivery conditions will be formed after interest from potential buyers.
    Table 1. Specifications
    ParameterSpecifications
    Dimensions (maximum)LWH: 115x75x35mm
    Number of video channels 720x5764; MCX input connectors, 75 Ohm
    Number of frames / second 720x5764 x 25 = 100
    Number of audio channels4
    Ethernet 10/100Yes
    USB 2.0 OTGYes
    GSM / 3G (optional)Yes
    Wi-Fi (optional)Yes
    CAN bus (optional)Yes
    Discrete inputs isolated (option)5 pieces.
    Discrete outputs isolated (option)6 pcs
    Nutrition12V / 24V DC is implemented on a separate module. The presence of surge protection, reverse polarity, suppression of short-term surges
    Indicator LEDs9pcs: 1x each video channel (4pcs.), 2x Ethernet, 1x (two-color) processor status, 1x power state, 1x hard drive state

    3D models

    Below are 3D models of the device board stack. After the assembly of the prototypes, photographs of the registrar will be presented.

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    Fig. 1. View from above. Microprocessor board recorder.

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    Fig. 2. Stack boards and hard disk recorder. Front view. From left to right: 4 video inputs (MCX-75 connectors), 2 stereo audio inputs (allow you to get 4 audio channels through a standard 2-> 1 adapter), Ethernet 10/100 input through a standard RJ-45 connector. The SIM card for the wireless module is inserted on the left side into a special convenient slot with a card holder.

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    Fig. 3. Stack of circuit boards. Back view. The installed digital output / output module is shown. Bottom row from left to right: RS-232 / RS-485, discrete input / output connector, micro-USB; top row: power connectors, digital inputs / outputs, CAN.

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    Fig. 4. Registrar fee. Bottom view: HDD2.5 is mounted under the board. MMC connectors for GSM and Wi-Fi antennas are located on the side of the device.

    The case of the registrar is supposed to be aluminum. All connectors are equipped with latches that provide reliable connection of external cables to the device. Consider the listed parameters in more detail.

    Number of cameras

    The optimal number of cameras used in oversized recorders is considered to be 4 pieces ... For stationary use, cameras can be used both for viewing the territory along each side and inside a residential building (apartment, house). For mobile applications such as automobiles, buses, motor homes, etc., 4 cameras are also used.

    Video quality

    Good quality can be ensured not only by using HD video resolution, but also with conventional analog cameras with a resolution of 720x576. Unfortunately, even this resolution of video recording today is not supported by all registrars. It should be understood that the quality of the video depends not only on the characteristics of the recorder - its internal design, the quality of the printed circuit boards, the use of appropriate connectors and video processing algorithms. The quality is also determined by the optics of the camera, its sensor, as well as the competent laying of the video transmission medium, i.e. coaxial cables.
    In some cases, it is necessary to obtain still frames when analyzing individual scenes. The use of algorithms that eliminate temporary redundancy between frames (Inter coding) degrades the quality of individual frames. Eliminating only spatial redundancy (Intra coding) increases the amount of data after compression. The user must be able to select a compression mode. Using the latter compression mode increases the likelihood of information recovery, in the event of loss or distortion of individual frames due to the lack of time dependence between frames.

    Real time recording

    There are very few multi-channel recorders with small dimensions on the market that can record 720x576 pixels from all cameras in real time, i.e. 25 (frames / s) from each camera. Typically, manufacturers indicate the total number of recording frames for all cameras in total, and it is usually less than 100 for 4 channels at maximum resolution for small dimensions of the recorder. The low speed of video recording can play a negative role in observing rapidly developing events.

    Audio

    Audio input channels are not always required. Often they are not used, even if they are provided. In some cases, the presence of audio recordings synchronous with video streams may be in demand.

    Storage medium

    A storage medium is essential, because without it, the system loses its meaning for offline use. Today, recorders use both conventional hard drives and memory cards, or solid-state hard drives. A regular hard drive is the easiest and cheapest way to store recordings per unit of memory. The volumes of modern discs allow you to store video for weeks, and if recording is only by event, for example, by the movement of an object in the territory, then a disk of 1 terabyte for 4 cameras with a resolution of 720x576 each can last for a long time.
    Solid state drives are rarely used due to their high cost and higher consumption. In the future, they, of course, will become cheaper, but so far they are used in critical applications where security is more expensive than the money spent.

    Access to video over the Internet

    Imagine that you went on vacation and left your home unattended, but under the alarm. The triggered sensor (movement, shock, alarm, etc.) sends a signal to the recorder, and that in turn sends you a message on the phone. It becomes possible to monitor what is happening in your apartment, house or car from a telephone over the Internet and take appropriate actions based on the results of the monitoring.

    Ethernet

    The presence of a port allows you to use the device without a storage medium, only as an IP camera. If a WEB server is running on the device, then it becomes possible to view video data and device settings on any platform where modern browsers are supported, without installing additional software.

    USB port

    This port in USB OTG mode allows you to quickly connect to a personal computer. When connected to a computer, you can make various kinds of settings for the registrar, as well as copy video data to a computer. In this mode, when connected to a PC, the available files are presented to the user as on a regular USB Flash drive.

    RS-232 / RS-485 Ports

    These ports allow you to build a more complex surveillance system, for example, they provide the ability to control cameras. If the recorder has an Ethernet port, you can control the cameras via the Internet. Also, on the basis of the RS-485 interface, some industrial protocols of a higher level are built, for example ModBus, ProfiBus, which also allows integrating the registrar into a more complex system.

    Dimensions

    Dimensions often determine one of the main reasons why the user prefers such a product. Who needs devices the size of a DVD player, or a VCR? If you want to install a registrar at home, then most likely you need to put it in an inaccessible and secretive place, so small dimensions are just what you need. If we are talking about use in cars, then this, along with video quality, is one of the decisive factors. The multi-channel recorder in this case should be compact.

    Power Supply 12V / 24V

    Possibility of power supply from 12V / 24V - designed for use in a car. For use in homes, you will have to purchase a 220V-> 12V / 24V power supply. Also, 12V / 24V power is possible for industrial applications. It is also worth noting that the recorder should provide protection against reverse polarity and from high voltage surges, since there are a lot of interference along the power line in the car and power surges are several tens of volts above the onboard rated voltage.

    GSM / 3G Wireless Module

    This option, of course, is needed not by everyone, but by those who want to build a real security system based on a small box - a video recorder. The advantages of this feature are described above. Ideally, when the module supports both GSM and 3G type of communication. Those. Who needs it - can only receive notifications in the form of SMS. Someone needs to get video from the camera to the phone, so they need a 3G connection.

    Wi-Fi Wireless Module

    Wi-Fi today allows you to communicate with many mobile devices at a distance of 100m or more. The presence of this type of communication makes it possible to copy information from the registrar to a display device (smartphone, tablet, GPS car navigator) and view it. Let's say the recorder is in your car and you also have a GPS navigator. In the event of any incident, you contact your registrar using a GPS navigator over Wi-Fi, and copy video to it for viewing, and then view it on the spot. In this case, you do not need a bulky recorder near the windshield, you have only mini-cameras fixed, and a multi-channel recorder is hidden under the rear seat, or in the trunk. Those. the system is very convenient, you don’t see constantly recorded video,

    Discrete input / output module and CAN interface

    The advantages of this option are also described above. It should only be said that such a module allows you to put your car in almost complete control. The main thing is that the number of discrete inputs / outputs is sufficient. CAN-bus allows you to read many parameters of the car, as well as control some of them.



    We are ready to continue the series of articles on issues of interest to readers. ARMiSoft
    Company ( www.armisoft.net ), email: habr@armisoft.net

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