SIGINT -Signal Intelligence

SIGINT is abbreviated from SIGnal INTelligence. It is one of the major forms of intelligence. Signals Intelligence satellites are designed to detect transmissions from broadcast communications systems such as radios, as well as radars and other electronic systems. The Interception of such transmissions can provide information on the type and location of even low power transmitters, such as hand-held radios. However, these satellites are not capable of intercepting communications carried over land lines, such as undersea fiber optic cables.

Signals Intelligence (SIGINT) comprises of Communications Intelligence (COMINT), which is directed at the analysis of the source and content of message traffic. While most military communications are protected by encryption techniques, computer processing can be used to decrypt some traffic, and additional intelligence can be derived from analysis of patterns of transmissions over time. Electronic Intelligence (ELINT) is a devoted analysis of non-communication electronic transmissions. This would include telemetry from missile tests (TELINT), or radar transmitters (RADINT).

Signal detection

Even if a signal is human communications (e.g., a radio), the intelligence collection specialists have to know it exists. If the targeting function described above learns that a country has a radar that operates in a certain frequency range, the first step is to use a sensitive receiver, with one or more antennas that capture signals in every direction, to find an area where such a radar is operating. Once the radar is known to be in the area, the next step is to find its location.

If operators know the probable frequencies of transmissions of interest, they may use a set of receivers, preset to the frequencies of interest. These are the frequency (horizontal axis) versus power (vertical axis) produced at the transmitter, before any filtering of signals that do not add to the information being transmitted. Received energy on a particular frequency may start a recorder and alert a human to listen to the signals if they are intelligible (i.e., COMINT). If the frequency is not known, the operators may look for power on primary or sideband frequencies using a spectrum analyzer signals. Information from the spectrum analyzer is then used to tune receivers to the signals of interest. For example, in this simplified spectrum, the actual information is at 800 KHz and 1.2 MHz.


The earliest, and still common, means of direction finding is to use directional antennas as goniometers so that a line can be drawn from the receiver through the position of the signal of interest. HF/DF knowing the compass bearing from a single point to the transmitter does not locate it. Where the bearings from multiple points, using goniometry, are plotted on a map, the transmitter will be located at the point where the bearings intersect. This is the simplest case; a target may try to confuse listeners by having multiple transmitters, giving the same signal from different locations, switching on and off in a pattern known to their user but apparently random to the listener.

Individual directional antennas have to be manually or automatically turned to find the signal direction, which may be too slow when the signal is of short duration.

Traffic analysis

It is the study of who is signalling whom and in what quantity. When locations are known, usage patterns may emerge, and inferences are drawn. Traffic analysis is the discipline of drawing patterns from information flow among a set of senders and receivers, whether those senders and receivers are designated by location determined through direction finding, by addressee and sender identifications in the message, or even MASINT techniques for “fingerprinting” transmitters or operators. Message content, other than the sender and receiver, is not necessary to do traffic analysis, although more information can be helpful.

GSM and CDMA Cellular Interception Technology

Cellular Intercept is the technology used to monitor cell phone calls and cellular communications.

It is possible to listen to a terrorist and/or criminal cell phone calls and gather Communication Intelligence or COMINT on their dark activities. In today’s unstable environment, the need for intelligence information is vital in preventing and combating crime. Of equal importance is the collection of evidence to convict suspected criminals. Nothing supersedes the need to stop criminals before they strike, and bring outlaws to justice.

What are the popular forms of cellular interception? GSM Intercept has become the most popular form of Cellular Interception as GSM Cellular Interception and CDMA interception together targets Cellular Networks. GSM Intercept as the primary form of cellular interception is based upon the fact that networks such as TDMA / AMPS are being replaced by GSM.

CDMA cellular interception would, therefore, be considered as the secondary popular form of cellular interception. CDMA intercept involves the targeting of CDMA Cellular Networks. CDMA interception together with GSM Interception represents the primary and secondary goals when achieving cellular interception. However, cellular interception of TDMA / AMPS is still available depending upon the geographic and demographic setup of the cellular network (this varies from country to country).

Cellular Interception GSM Intercept is tactical off the air GSM Mobile Phone Intercept System, designed as a GSM Intercept and tracks GSM cellular telephone traffic in a local area. GSM Interception for cellular interception of cell phone conversations is legal l intercept tool.

GSM Interceptor equipment is used for GSM interception to gather intelligence on suspected criminals and terrorists. No hard wired connection to the cellular provider is necessary, as the GSM Interceptor can intercept GSM signals off the air.
Optionally, the GSM Mobile Phone Intercept System can be custom built to fit inside of a surveillance van in order to monitor & track multiple conversations. The GSM Interception system can also record real time off air intercept of GSM phone calls for future review. The GSM Intercept is a tactical intercept, enabling the user to pursue suspects in cities, country sides, and while traveling.

Cellular Interception CDMA intercepts, records, and playbacks CDMA cell phone conversations from a CDMA mobile phone network. The CDMA Cellular Monitor is used to monitor and store CDMA cellular phone conversations of suspected criminals, militants, terrorists, and those committing espionage.

The CDMA Intercept also functions as an SMS Intercept, able to capture SMS (short message service) data. The CDMA Intercept is a passive system, in which no signal is transmitted from the cellular interception system. In addition, the CDMA Intercept does not affect the cellular communication between the cellular phone handset and the cellular service provider. Therefore, the cell phone network receives no electromagnetic interference.

This cellular intercept system operates by automatically detecting the strongest signal in a CDMA service area. Working as a mobile phone intercept on global CDMA networks, the CDMA Cellular Monitor also intercepts and control channels on both sides of a conversation through traffic channels.

GSM Intercept System a5.1

The GSM Interception system can break the GSM A5.1 encryption algorithm used in GSM communications during real time operation enabling Stratign to track and monitor the activities of suspected terrorists and criminals. GSM Interception for the A5.1 protocol deciphers the encryption format used to secure GSM A5.1 communications.

It can also operate with the optional Word Identifier used to capture words or phrases from a pre-determined threat database. This can enable us to conduct GSM Cellular Interception of A5.1 and review communications for trigger words, names, and other audio voice codes used by suspected terrorists or criminals.

The Word Identifier is an integrated optional feature that can enhance GSM Interception for COMINT.

VSAT Interception and Logging Infrastructure

Communications Intelligence (COMINT), involving the covert interception of foreign communications, has been practiced by almost every advanced nation since international telecommunications became available. COMINT is a large-scale industrial activity providing consumers with intelligence on diplomatic, economic and scientific developments.

VSAT Interception

The VSAT Interception and Logging system are designed for the real-time collection and traffic analysis of VSAT Satellite Networks. The system provides total traffic (Voice/ FAX, Data and Multimedia) analysis of TDM/TDMA and SCPC DAMA systems.

GSM Communication Interceptor

Throughout the evolution of cellular telecommunications, various systems were developed without the benefit of standardized specifications. This presented many problems directly related to compatibility, especially with the development of digital radio technology. In 1982, The GSM group (“Groupe Spécial Mobile” [French]) was formed to address these problems.

Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. GSM service is used by over 2 billion people across more than 210 countries and territories. Data communication was built into the system from the very beginning. GSM is an open standard which is currently developed by the 3rd Generation Partnership Project (3GPP).

The advantage for network operators has been the ability to deploy equipment from different vendors because the open standard allows easy inter-operability.

Easy inter-operability definitely raises the question of security. Is the system Secure? Can the security be breached?
GSM was designed with a moderate level of security. The system was designed to authenticate the subscriber using shared-secret cryptography. Communications between the subscriber and the base station can be encrypted. The development of UMTS (Universal Mobile Telecommunications System) introduces an optional USIM (Universal Subscriber Identity Module-the 3G equivalent of the GSM SIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user – whereas GSM only authenticated the user to the network (and not vice versa).

Keeping this in mind, Communication Intelligence groups have been continuously working for developing various systems which can help you intercept any system of mobile communications. One such system is a GSM Interceptor, a system which is compact, innovative and can monitor and log GSM communications in real time.

The GSM Interception system, thus developed, can be configured in any LAN environment to provide a near-exact physical location of the target and to form a Central Interception Station. The system auto-detects, decodes and records telephone conversations, network information into the digital media (magnetic / optical) present in the system. The system provides Interception of Short Message Service (SMS) traffic. The system of GSM Interception is intended for search, interception and registration of cellular signals on standards GSM-900/1800 in stationary or in a mobile variant.
The need of the hour is pointing towards a more descriptive technology of Data Interception.