E-ear IP microphones. Everything is under control - remote listening Expansion of the mixer structure will allow the use of more than four microphones

Audio surveillance has long been the talk of the town both in Russia and abroad, and its history is longer and richer than that of video surveillance. Historically, the majority has a negative attitude towards it, although, like any tool, audio surveillance itself is neutral and completely depends only on whose hands it is in. Before the start of the digital era, it relied exclusively on radio broadcasting, but progress, as we know, does not stand still, and now a simple Wi-Fi networks. Microphones capable of recording sound over IP will be discussed in this article.

First, let's talk about the relevance of audio surveillance in combination with video surveillance. Many people make do with cameras without sound (they are, of course, cheaper than their sound-receiving counterparts) and are satisfied with the resulting silent film. However, a microphone for a camera brings with it many benefits: firstly, night time and simply poorly lit areas, as a rule, have a bad effect on the quality of the resulting video. Even with infrared illumination, finding a camera that can see well (more than a couple of meters) in the dark is not an easy task. The darkness does not contain the sound in any way, moreover, at night extraneous noise much smaller, and the sound spreads and is captured better. The soundtrack attached to the video also significantly increases the information content - the operator/administrator receives a more detailed picture. It is also worth paying attention to the position occupied by the cameras: in order to maximize the area of ​​the room in the frame, they are usually hung in the corners. Here lies the contradiction between optimal audio and optimal video. Sound, being a wave of air pressure generated by the vibrations of an object (for example, the vocal cords), spreads from the source in all directions. These fluctuations with certain frequency and the amplitude is captured by the sensitive membrane of the microphone, oscillates itself and converts them into alternating electricity different voltages. This is how sound recording works. In this case, the microphone is greatly interfered with by large flat surfaces - ceilings and walls: the waves bounce off them, overlap one another, generating echo and other distortions. Therefore, the corner of the room is perhaps the worst possible position for him.

So, a separate microphone for the camera will definitely come in handy. Where to get quality sound recording device so that you can link it to Xeoma? Just recently we found a worthy answer to this question: microphones E-ear produced by the Electronic Shield company. These compact sensing devices are easy to install indoors or outdoors while receiving sound High Quality. The kit looks like this:

It’s easy to work with them - add a module to the chain "Microphone" and select E-ear in the drop-down list:

From here we only need serial number- copy it to the corresponding settings field in Xeoma. Below we find this section:

In the User Service and Media Service Address columns we indicate the IP address of the computer running Xeoma (if the networks are different, then the server will need a static external IP), in the Media Service Port we indicate any free port. We also make sure that in the Select service column there is 3 Media service. In Xeoma we get this picture:

The audio channel number determines which microphone to listen to, since several can be connected to one device.
All is ready! Connecting "Microphone" to an existing module "View and Archive", and the sound recording will be archived over the video.

Finally, you should pay attention to the legal side of the issue. Both video and audio surveillance are directly related to Article 137 of the Criminal Code of the Russian Federation “Violation of privacy”, which clearly indicates the illegality of collecting information about a person’s private life without his consent. In this regard, it is especially important to mark the places where such surveillance is carried out with appropriate signs/placards.

Thus, good microphone for a camera is by no means a luxury, but a prudent investment in your security system.

PURPOSE

IP microphone OCA P1LN is an independent network device that has its own IP address and is designed to convert an acoustic signal into a digital audio stream, for its subsequent transmission via Ethernet and Internet channels using various protocols to an audio server or video surveillance system for recording, processing and storage.

COMPOUND

IP microphone OCA P1LN is:

COMPARISON

PRINCIPLE OF OPERATION

ADVANTAGES OF IP MICROPHONE

INSTALLING AN IP MICROPHONE

1st step	2nd step	3rd step
Selecting an installation location and connecting to a local network	Installing "Recorder" software on a computer	Adding a device to the R-Server recording program.
The installation location of the IP microphone is selected based on the task at hand, preferably near an outlet for connecting to a local network. The IP microphone can be placed on a table, on a wall, on the ceiling, on a shelf, or in other places that are most suitable for each specific case.	Installation is done from the CD that comes with the microphone. Almost anyone can act as an audio server modern computer or laptop. After installation, the “R-Server” folder will be created in the “All Programs” folder, which will contain all the programs and utilities necessary for operation.	To add an IP microphone, you need to run the "IP Transmitter Service" utility, which will detect a new device on the local network and connect it to the Recording Program. By default, the average parameters for acoustic triggering are set, which will ensure that recording begins when an audio signal source appears near the IP microphone.

IP MICROPHONE SETTINGS

	- Adding an IP microphone in the IP Transmitter Service.
	- Changing the name of the recording channel and setting recording modes and sound quality for each IP microphone.
	- Online listening from an IP microphone.
	- Search for the desired recording in the archive by date and time and save the desired recording as a .mp3 or .wav file

- Setting a unique device name.	- Online listening to sound on VLC player on a computer, tablet and mobile phone.
- Change network settings devices: IP address, mask, gateway, port.	- Connecting an IP microphone to an IP DVR via RTSP protocol to a separate channel.
- Changing the access password for the IP microphone.	- Integration of an IP microphone with IP video surveillance for synchronous video and audio recording.
- Setting the RTSP address and microphone port.	- Linking an IP microphone to any IP camera.

IP MICROPHONE FIRMWARE OPTIONS:

Firmware for working with the "Recorder" software	Firmware for working via RTSP protocol
This firmware allows you to use an IP microphone to transmit audio over a local network to a computer. To work in this mode, you only need the OCA P1LN IP microphone and the “Recorder” software included in the kit.	This firmware allows you to receive sound from an IP microphone in online mode using VLC media player, as well as for integration with an IP video surveillance system via the RTSP protocol.
VIDEO on setting up an IP microphone with the "Recorder" software	VIDEO on setting up an IP microphone on VLC player
	Recording negotiations in the meeting room between manager and client
Recording a conversation between a clinic doctor and a patient	Recording a conversation between a salon salesperson and a buyer	Recording of a conversation between a travel agency salesperson and a client.	Recording of communication between a hotel or fitness club administrator and a visitor

ADDITIONAL INFORMATION ABOUT OPTIONS FOR USING IP MICROPHONE IN PRACTICE.
READY SOLUTION FOR RECORDING CONVERSATIONS BETWEEN A CONSULTANT AND A CLIENT BASED ON IP MICROPHONE OSA P1LN

CONTENTS OF DELIVERY:

• IP microphone OCA P1LN.
• Power adapter with POE - 1 pc.
• Network cable(patchcord) 1.2 m - 2 pcs.
• Disc with “Recorder” software and instructions

SETTING UP AUDIO BROADCAST ON A MEDIA PLAYER

The audio information transmitted from the IP microphone can be listened to on a media player that supports broadcasting via the RTSP protocol. Let's look at an example of setting up a broadcast using the VLC media player as an example.

Launch the VLC media player.

Go to "Tools - Settings - Water/codecs", go to the very bottom of the page and check the box "RTP over RTSP (TCP)" and close this tab (see the figure below).

After that, select "Media - Open URL" and indicate network address Signal source (IP microphone OCA P1LN) via rtsp protocol. See the example in the picture below.

After entering the address, you must press the button "PLAY". Connect the media player to the IP microphone and broadcast the audio stream. The volume is set individually.

In the audio stream broadcast mode, you can open statistics and see what data stream is being received and at what speed. To do this, go to the "Tools" menu and select the "Media File Information" tab. Go to the "Statistics" tab. A window will open as shown in the figure below.

When you go to the "Codec" tab, you can see which codec the IP microphone is currently using and what the sampling frequency is.

The broadcast mode works reliably on VLC media player installed on any phone and computer. The VLC media player program can be downloaded for free from the Android Market (for Android phones) or in App Store(for iPhone).

Life is unpredictable, and therefore sometimes situations arise in which it is necessary to remotely and secretly listen to premises, some conversations on the street or in other places. Without touching on the moral side of the issue, let's consider the fundamental principles of wiretapping at a distance. Which technical devices are they allowed to do this? What are their features? What does someone who decides to buy long-distance wiretapping need to know? – you will find answers to these and other questions in this short review.

Wiretapping at a distance - the theoretical side of the issue

There are several ways to carry out remote and secret listening:

• Interception of sound waves. Without delving into physics, we note: sound is mechanical vibrations of the air, which can be detected by a special device - a microphone.
• Air vibrations also cause vibrations sound frequency physical objects: glass, walls, some other surfaces, and therefore, by removing these vibrations from the objects themselves, you can also get a sound “picture” of the space surrounding them. This feature underlies the operation of special equipment for wiretapping at a distance.
• Another method, which is only suitable for listening to people talking, is to watch the movements of the speaker’s lips with simultaneous translation.

These are all currently known methods of remote and covert eavesdropping. IN this review We will not dwell on the possibility of reading lips and removing vibrations from the surfaces of objects. First of the above methods is extremely difficult because it requires a special kind of skills, and the second requires the use of special, expensive and complex equipment.

How does remote wiretapping equipment work?

Today you can buy wiretapping at a distance in Moscow and other cities without any problems, but let's figure out how devices of this kind work.

You can listen to sound remotely in the following ways:

• First install a “bug” at the place of conversation that transmits a signal via a wire line or radio channel to the receiver, through which the sound will be listened to and (or) recorded;
• Install a radio transmitting microphone on people or a dog, and they, if necessary, will move to the place where the conversation of interest is taking place;
• First, secretly install a sound recording device (dictaphone) in the place where the dialogue you are interested in will take place, and then remove it and listen to the recording;
• Using special devices - directional microphones, listen and (or) record the conversation of interest remotely.
• To listen to a conversation indoors, install a special kind of sensitive microphone on the wall, something like a stethoscope.

Let's consider some of these methods in more detail, namely: radio and directional microphone. It is these two options that are most widespread in practice.

Radio microphone as a device for listening at a distance

The most common way is to secretly install a miniature “bug”, which is a special microphone and transmits a signal to a remote receiver. The use of a wired signal transmission line is extremely rare: it is necessary to pull the wire, which cannot be done covertly. The most popular currently is GSM mini wiretapping, which transmits a signal through channels cellular communication, and therefore through them you can listen to a conversation anywhere in the world using a regular mobile phone

Let's get on practical example Let's look at the features of such a device, one of which is.

The presented GSM wiretapping at a distance, bugs can be bought today at a very reasonable price, and the quality and functionality allows us to classify this device as professional; it can act both as an audio alarm and as a device for monitoring the listening of premises and any other places. The device has two modes: the ability to turn on by voice, followed by a call to a preset cellular telephone, as well as continuous listening mode.

The range of the microphone is 10 meters, and the size of the device (40*30*10 mm with a weight of 24 grams) allows you to hide it anywhere: a bag, clothes, inside the glove compartment of a car, and hide it indoors so that you can accidentally find the bug itself will be almost impossible.

The operating time from a fully charged battery in listening mode is up to three hours, and in alarm mode – from two to four days - it all depends on the number of alarms and, accordingly, dialing. In standby mode and with a fully charged battery, it is guaranteed to work for three to five days.

For communication, the bug uses cellular communication channels in the 900, 1800 and 1900 MHz range, i.e., it is fully supported in our country.

The operating temperature range is from minus forty to plus fifty degrees Celsius, i.e., work is possible in any heated or unheated room, as well as in the open air. The main condition is a stable cellular network.

Many installation organizations are faced with the fact that a single active microphone, even with outstanding characteristics, is often unable to cope with listening to a room or large hall with complex acoustics.
For large halls, an obvious solution to improve the listening quality of the entire area is to use several microphones. In this case, the microphones should be positioned so that their sensitivity zone covers the entire area of ​​the room and partially overlaps with each other. But then the question arises of connecting these microphones to a video camera or audio recorder.
Simply paralleling microphones to one audio input will give a bad result, since this will deteriorate the line parameters (capacitance, resistance, inductance) and, consequently, the quality of the audio signal will deteriorate, and at moments when the signals of different microphones will be in antiphase, they will be subtracted from each other from a friend, causing some audio dropouts in the recording.

STELBERRY mixers

Audio mixers of varying complexity have long been widely used in recording studios to combine and summarize audio signals from various sources.
But for some reason, until recently, such a widely known and integral device for audio studios has not received the same wide distribution in the security and audio-video surveillance environment.
The STELBERRY MX-300, STELBERRY MX-310 and STELBERRY MX-320 mixer models are designed to correct this unfortunate situation and raise the capabilities of security systems to a new level.
The main characteristics of these mixers are the same, and their main difference lies in the functionality of the settings menu, or in other words, in the comfort of making settings.
Each of the MX-300, MX-310, MX-320 mixers allows you to connect up to four active microphones to its line inputs (and not only active microphones) and configure each channel by signal level individually, or in comparison with other channels.

In the MX-300 mixer, each channel has its own independent signal level control, and if you need to adjust the signal of a microphone or other line signal source independently of other channels, you will have to physically disconnect them by removing the corresponding connectors from the mixer.
In the MX-310 mixer, each channel is initially configured independently of other channels, and it is possible to listen to the overall sound picture without leaving the settings menu.

The MX-320 mixer gives the user the ability to independently select which of the four channels will be active, and make channel adjustments, either independently of each channel from the others, or in comparison with one or more channels.
The ability of this mixer to quickly change the configuration of the involved channels without physically turning them off will be convenient if the furniture arrangement in a certain room often changes or the area of ​​active presence of people is often moved.

An interesting feature of STELBERRY audio mixers

STELBERRY audio mixers have such an interesting feature that all of these mixers have linear audio inputs and linear audio outputs.
And this feature allows you to expand the structure of sequentially connected audio mixers, connecting the outputs of some mixers to the inputs of other mixers.

That is, if one mixer allows you to connect only four active microphones, then the outputs of four mixers connected to the inputs of the fifth mixer will already allow you to use a cluster of sixteen active microphones.

Choosing a microphone for a large room

What active microphones are best suited for listening to rooms in conjunction with mixers? Taking into account the fact that background music can be playing in the hall, or ventilation or air conditioning can be heard, these should definitely be microphones without AGC ( automatic adjustment gain) or with switchable AGC. Only indoor microphones without AGC will maintain speech intelligibility in a variety of ambient noise conditions. If you use microphones with AGC, then the automatic gain control will adjust to the background noise and pull it up to the level of the microphone’s output signal, and only this noise will dominate the recording, and the useful signal will be suppressed by it.

Listening to long rooms and corridors

Acoustically complex rooms are usually elongated halls or corridors, as well as large empty or semi-empty halls, where sound is given the opportunity to freely and repeatedly reflect from the walls, floor and ceiling. In such rooms, it would be optimal to place microphones along the room or corridor with a certain step, depending on the sensitivity of the selected active microphones with the condition that there are no blind areas between the microphones.
For example, in such a long room, when placing microphones on the ceiling with a ceiling height of 2.5-3 meters, M-20 microphones should be located approximately 3-4 meters apart, and M-60, M-70, disconnected AGC, should be located at a distance of approximately 7-8 meters from each other.
In this case, the sensitivity of active microphones is adjusted so that they slightly overlap the sensitivity zones of neighboring microphones. Microphones with fixed gain, although cheaper, provide more difficulties with placement settings, due to the need to more accurately select the height of their suspension and mounting pitch.

Microphones with sensitivity adjustment are better

Adjusting the sensitivity of microphones with a slight overlap of the sensitivity zone of neighboring microphones will minimize the effect of boom and echo, and also avoid voice dropouts when moving talking people in a room or corridor.
The installed microphones are then connected to a mixer such as the MX-300. And then, on the mixer, the gain of each channel is adjusted so that the signals from the microphones are the same in volume. And then, at the customer’s request, the signal from the mixer is fed to an autonomous audio recorder, for example SPRUT-SR, or, if video surveillance is being carried out in the room, then to the linear audio input of the DVR or the linear audio input of the IP camera.
This example of microphone placement is somewhat arbitrary, as is the conventionally chosen room for the example. In fact, in practice, the pitch and placement option for microphones must be selected experimentally for each specific room, and there is no universal “recipe” here; each room will have its own nuances that require a solution on the spot.

Listening to trading floors

The trading floor is a classic version of a large listening room for which one microphone is clearly not enough.
After all, staff and clients can move freely, complicating the conditions for audio recording.
But often, for small shops whose floor area is not too large, it is enough to place no more than four active microphones M-60, M-70 on the walls or ceiling, which will be connected to one mixer, for example MX-300,
and the combined signal from the mixer output is fed to the linear audio input of the SPRUT-SR autonomous audio recorder.

Placement of microphones in the hall

If the room is close in shape to a square and the room area is approximately 250 m² and the ceiling height does not exceed 2.5-3 meters, then it is enough to place four M-60 or M-70 microphones, with AGC disabled, closer to the ceiling on the walls at points located in the middle of each wall. If the area of ​​the room with ceilings of 2.5-3 meters exceeds 250 m², but not more than 1000 m², then four microphones and one mixer are sufficient. Microphones M-60, M-70, with AGC disabled, in this case are located on the ceiling in the corners of a virtual square in the center of the hall. There should be a distance of eight meters between microphones in all directions.

Accordingly, if you have a larger room and a sufficient number of audio channels, you will have to increase the number of microphones and increase the number of mixers. And if you have only one audio input for recording conversations, then you will have to expand the structure from

mixers, when the outputs of 2-4 mixers are connected to the inputs of the third to fifth mixer. Again, these are general guidelines. In practice, the pitch and placement of microphones will have to be selected experimentally for each specific room.

Listening to the sector in a huge trading floor

For very large trading floors, the hall is divided into sectors depending on the categories of goods, and usually one or two managers or sales consultants are allocated to one such sector, who will advise clients and prescribe the goods chosen by clients. And here, to control the quality of customer service, it would be good to hear how a manager or consultant in this sector communicates with the client, what products he offers and whether he offers them at all.

Expanding the mixer structure will allow the use of more than four microphones

Racks and display cases with goods can stretch for several tens of meters, and there may be several rows of such racks in a sector.
Accordingly, this is where the ability to build up a structure of mixers comes in handy in order to distribute microphones throughout the sector, since one mixer with four microphones is not enough to listen to the entire sector area.

Typically, such trading floors have very high ceilings, and the walls may be located far from the placement of the sector with a group of goods, so the most rational option would be to place microphones on a suspension. The height of the microphone suspension can strictly depend on the height of the shelves with goods. And here we need to understand the dependence of the area of ​​the room listened to by the microphone on the height of its suspension.

The higher the microphone is from the floor, the more frequent the active microphones will have to be positioned so that blind areas do not appear between them.
Accordingly, when using a four-channel audio recorder, for example SPRUT-SR, you can organize listening to four such sectors with clusters of four microphones in each.

At the Amphion Forum conference a few days ago, Ang Cui, a student from the Department of Intrusion Detection Systems at Columbia University, read a report (presentation slides, pdf) on the topic of exploiting vulnerabilities in the CNU (Cisco Native Unix) kernel in Cisco IP phones 7975G, 7971G -GE, 7970G, 7965G, 7962G, 7961G, 7961G-GE, 7945G, 7942G, 7941G, 7941G-GE, 7931G, 7911G, 7906, 7971G-GE, 7970G, 7961G, 7961G-GE, 7 941G, 7941G-GE and 7906 .

The vulnerability in CNU is somewhat similar to the recently discovered one, that is, it gives an application with user rights access to physical memory devices. In this case, this is possible due to insufficient security checks for calls to the syscall function. Thus, an attacker gets the opportunity to rewrite arbitrary fragments of kernel memory and run any code for execution.

Ang Kui not only described the vulnerability, but also demonstrated in practice how it can be exploited, for example, to turn a Cisco IP phone into a hidden listening device without the user noticing. The malicious code gains root rights in the system, gaining access to the digital signal processor (DSP) and the device management interface. The student developed a patch that makes the necessary changes to the core and DSP, so that the IP phone, unnoticed by the owner, turns on the microphone and begins to covertly listen and record.

During his presentation, Ang Kui showed the fastest way to install such a patch on any IP phone. To do this, you need to make a small chip with the appropriate firmware, insert it into the phone's Ethernet port - and remove it after a second. After this, the phone is “reflashed” and can work as a “bug” and records all surrounding sounds. You can also install the patch remotely, via the Internet, although this will require some effort for the user to launch the file for execution. Thanks to the vulnerability in CNU, any program can gain root rights.

Ang Kui also discovered several libraries from third party developers on Cisco phones, which also have exploitable vulnerabilities. Using them, you can try to install malicious code to the device even without notifying the user. However, Ang Kui has not yet released information about vulnerabilities in third-party libraries, promising to disclose it at the hacker conference 29C3 (29th Chaos Communication Congress), which will be held from December 27 to 30 in Hamburg.

Cisco was previously notified of the vulnerability and released a corresponding patch for some phone models on November 2 (see bug CSCuc83860). It is recommended that all users install this patch as quickly as possible, since the exploit has already been released. open access. Interestingly, the researcher could not find the files on the Internet new firmware phones, that is, the owners of the devices cannot download them so easily. You probably need to contact the manufacturer directly.

For other models - in particular, 7971G-GE, 7970G, 7961G, 7961G-GE, 7941G, 7941G-GE and 7906 - no patches have been released because the phones are no longer in production. Owners of such devices are recommended to buy a newer model.

Ang Kui discovered the vulnerability in IP phones while working on the Gunman v2 educational project, in which they implemented a firmware update for network printer HP into a regular document. After processing such a document, the exploit penetrated the firmware and could distribute malicious code to computers on the local network. According to the researcher, now the majority network devices- such as printers and IP phones - have vulnerabilities and pose a threat to the security of the local network.

Ang Kui recalls the story of a year ago, when some unknown hackers penetrated the SCADA water supply system of one of the American cities and disabled the water pump, depriving the citizens of drinking water.

In the illustration for that news you can see a familiar model of an IP phone.