Name: ASN, Audio Surveillance Network

Text: Audio Surveillance



Audio Surveillance Network

1 Product Description
Audio Surveillance Network (ASN) is a complete solution for law enforcement
agencies to collect, transmit, store and analyze audio coming from distant targets at a
centralized location. ASN consists of both hardware and software elements suitable
for building a countrywide audio surveillance system, or to conduct standalone tactical
operations. A typical ASN layout consists of various target locations, remote location
sites, a central headquarters and a set of observer terminals.

Audio is captured form a target location by audio transmitters containing tiny
microphones, and transferred to the remote location site over a telephone line.
Usually, a remote location site exists near a location exchange. It contains a large bank
of receivers to collect audio from various target locations. The received audio channels
are digitized and stored in a remote location server.


The audio data is sent to the headquarters using a DSL or E1 link. The headquarters
stores digital audio coming from a number of remote locations in a huge database.
Observer terminals access the headquarters database using custom written audio
surveillance software. An ActiveX based audio player offers audio analysis capability
and on-line comment tag submission to the observers. ASN is the only system of its
kind that offers real-time audio surveillance from a number of distant targets from
beginning to end.
2 System Elements
The Following system elements have been developed to build an ASN.
Target Location

Xad Audio Transmitter (XTL-ATx)
Remote Location Site

Xad Audio Receiver (XKL-ARx)

Xad Audio Acquisition Platform (XRL-ACQ)

Xad Remote Location Server (XRL-SER)

Xad Remote Location Software (XRL-SW)

Xad Headquarter server (XHQ-SER)

Xad Headquarter Software (XHQ-SW)

Audio is collected from the target location using Audio Transmitters (XTL-ATx). Each
transmitter contains a high gain, sensitive microphone, which is installed on the target
line irrespective of the location and polarity. The installation does not interfere with
the normal operation of telephone equipment. XTL-ATx comes in two versions – XRLATP works with standard POTS, while XRL-ATA is designed for ADSL enabled
telephone lines. For major operations, up to four XRL-ATx units can be deployed per
target. A user can remotely activate the desired XRL-ATx leaving the others in standby
Each XRL-ATx has built-in intelligence to sense the line status and start-stop its
operation independent of the user intervention. Salient features of an XRL-ATx are
listed below:

Small size 16 x 9 mm

Low current consumption (active 4mA, standby 4μA

High gain microphone 48 dB

Polarity free installation

Seamless operations on PSTN and ADSL enabled lines

Automatic start-stop and mute functions

Choice of 4 transmitters per line



2.2 Audio Receiver (XRLS-ARx)
Audio Receiver (XRLS-ARx) is a very low noise state-of-the-art receiver to extract clear
audio signals from noisy telephone lines at a distance of 5 Km from the target
location. XRLS-ARx outputs receive audio to the headquarters and phono sockets.
There are manual control buttons on the XRLS-ARx to switch between multitransmitter installations or mute all, if required. XRLS-ARx also provides a digital
interface which is used to control XRLS-ARx from the headquarters’ software. Main
features of XRLS-ARx are listed below:

Transparent operations on PSTN and ADSL enabled lines

Standalone and network operation

Automatic voltage control

Manual button control for standalone operations

Digital control interface

Logic circuitry to control up to 4 audio transmitters

Built-in digital voltmeter

Audio Vu-meter

Automatic volume control

Phono socket

Headphone socket



2.3 Audio Acquisition Platform (XRLS-ACQ)
The Audio Acquisition Platform (XRLS-ACQ) is a 1U height 19 inch rack mount unit. It
consists of a custom built PCB to acquire, digitize and transfer 28 audio channels to a
Remote Location Server (XRLS-SER).

ACQ uses four 8-bit analog to digital converters to digitize the audio channels. The
digital audio samples are buffered before sending them to XRLS-SER using a USB 2.0
interface. Main features of the XRLS-ACQ platform are listed below:

19 inch rack mountable casing

Parallel A/D conversion of 28 analog audio channels

64KB buffer memory to ensure data continuity

High speed data transfer using USB2 interface

Integrated interface for audio and transmitter control using RJ45 ports

Acquisition status display



2.4 Xad Remote Location Server (XRLS-SER)
The Remote Location Server (XRLS-SER) is a powerful machine built with 64 bit AMD
2.0GHz dual core processor and Linux operating system. The industrial PC casing with
front and rear fan support provides ruggedness to operate in extreme temperatures
expected at a remote location site. The remote location server is lockable at the front
providing extra security to the system.

2.5 Remote Location Server Software (XRLS-SW)
The remote location server software (XRLS-SW) runs on XRLS-SER and controls the
main functionality of a remote location site. It is written in C++ under a Linux
operating system. For security reasons, a user interface has not been built in the
remote location software. The remote location operator uses a console window to
execute commands for each task. Main features of XRLS-SW are listed below:

Command line interface for added security and reliability

Security database installation without user interaction

Built under Linux for easy integration, faster speed and stability

Database storage for systematic archiving of audio streams

Automatic audio acquisition and uploading according to the headquarters’

Thread based real-time audio encoding and uploading

Local audio offload option for emergency

Segmentation of audio streams into packets for quick transmission

Synchronized time stamping of audio data cross the ASN

Lossless compression of audio data for integrity and completeness

Remote control of attached audio devices from the HQ software

Password protection, activity logging and secure reporting to HQ software

Memory management and automatic deletion of contents

Separate audio device set-up and local testing utility

Transmission Hardware
The requirement for transmission hardware (E1 routers, DSL and related components)
may differ in each case. Depending upon the requirement, we can specify the
transmission hardware to be used in an ASN.



2.6 Headquarter Servers (XHQ-SER)
The HQ is the main control center of the ASN. It is connected to remote location sites
in a star network topology. The XHQ-SER comprises two database servers, a storage
server, and an application server. The database servers are similar in specification to
XRLS servers. The storage configuration is tailored according to the requirements. To
build redundancy, the database servers are connected to the storage server in cluster
configuration. The application server is an apache based server, which hosts webbased HQ server software. It allows the observer terminal to access the huge audio
2.7 Headquarter Server Software (XHQ-SW)
The headquarter server software (XHQ-SW) provides the main control of the ASN.
XHQ-SW software is accessed by the Microsoft Internet Explorer through a Webbased environment. The complex system information remains hidden behind a user
friendly graphical user interface (GUI). All the software pages are interconnected. A
user can navigate across them using a dynamic menu bar. The menu items vary
according to the user access privileges.
The main features of the XHQ-SF are listed below:

Secure login feature with individual access rights

Personalized home page portal for each user

Easy and dynamic remote location site creation

Site and target location based user access

Hierarchical user and group management structure

Entity based access rights and on the fly user creation

Automatic information update across the network

Time, tag and target based audio content search

ActiveX based audio player with audio range control

Custom audio play list with forward/backward audio search options

Real-time audio access and analyze feature

Observer comment tagging and retrieval

Audio save option for privileged users

Automatic e-mail feature within the groups

Audio transmitter control for each remote location site

Network site status reporting

Advanced audio download scheduler for target locations

Activity log and reporting

2.8 Observer Terminals (OT)
Observer Terminals are standard PCs connected to the HQ server in an intra net
configuration. They access XHQ-SW to access and listen to audio records stored in
the HQ database. ASN setup does not require an installation of the client software.
Updates are automatically reflected to the observer terminals when XHQ-SW is
updated on the headquarter application server.




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