Specialized TSCM Equipment

The following list is presented to serve as general guidelines to assist in the evaluation of equipment capabilities and limitations. These may vary depending upon particular requirements, based on the level of risk. Indicated equipment capabilities represents the minimum required to perform a thorough TSCM Survey.

The recognized equipment manufacturers indicated is by no means complete or conclusive.

Telephone Instrument Analyzers
Telephone Instrument Analyzers must be designed to detect hookswitch bypass devices and wiring modifications inside the telephone instrument, which would allow the interception of telephone and/or room conversations. Equipment must also be capable of activating and detecting both single and multi-tone devices, as well as other various types of remotely activated hookswitch bypasses. Depending upon particular requirements, analyzers must be capable of interfacing with all three generations of telephone instruments: electro-mechanical, electronic, and digital electronic.

Conventional analyzers are limited to voltage meter and passive line amplification tests. These analyzers are not capable of activating or detecting remotely activated hookswitch bypasses.

Telephone Instrument Analyzers are not designed to detect wiretaps, and will not detect the simple parallel wiretap sold by Radio Shack.

Recognized equipment manufacturers are Dektor CIS, and Information Security Associates (ISA). These analyzers range in price from $4,000 to $20,000.

Time Domain Reflectometers (TDR)
The TDR is one of the most valuable TSCM test instruments available. This equipment is capable of detecting many wiretap methods that are undetectable by conventional telephone analyzers, meters or other instrumentation.

The TDR is designed to reveal all wire irregularities (impedance mismatches) by displaying the characteristic signatures and distances to each wire irregularity. Without a TDR, the presence and location of all wire irregularities cannot be pinpointed, and therefore will not be physically inspected. This can also establish possible previous wiretap activity, or modifications intended for future use. Since many wiretap operations are fairly short-lived, this information can be extremely important. Without a TDR, the TSCM technician would be unable to detect hidden parallel bridge taps, split/resplit inductive wiretaps, mini-taps or other forms of clandestine telephone line modifications.

Recognized equipment manufacturers are Tektronix Inc., Riser-Bond, and James Biddle Company. These cable radar type devices range in price from $2,000 to $10,000.

Spectrum Analyzers
The Spectrum Analyzer is a swept receiver that provides a visual CRT display of all known radio transmitting modulation techniques. This allows for RF signal detection with a visual display of amplitude versus frequency.

The RF Spectrum must be analyzed with a Spectrum Analyzer capable of covering a minimum frequency range of 3 Khz to 2.5 GHz. Equipment must be capable of detecting carrier current devices on power lines as well as demodulating subcarrier transmissions. Sophisticated techniques such as frequency hopping, spread spectrum and video transmissions must also be addressed.


The spectrum analyzer has the following advantages over a tunable receiver and other search receivers, if frequency range and sensitivity are equal between the two:

While the tunable receiver detects by demodulation, it can detect only that type of modulation for which it was designed. Because the spectrum analyzer displays how energy is distributed as a function of frequency. Any type of modulation applied to a previously unmodulated carrier will result in an observable display change.

The same inherent characteristics allow the direct detection of subcarrier or sub-subcarrier, since the subcarrier(s) display themselves as side bands from the original carrier and are responsive to sound changes as discussed above.

Companies using broadband regenerative feedback receivers, police scanners and field strength meters are severely limited in their capability to detect the modern eavesdropping transmitters using sophisticated modulation techniques.

RF receivers will not detect remotely controlled transmitters or units with dead batteries.

Recognized manufacturers are Tektronix, Hewlett Packard, Information Security Associates (ISA), Research Electronics International (REI), and AudioTel

These instruments range in price from $5,000 to $80,000.

Non-Linear Junction Detectors
The Non-Linear Junction Detector (NLJD) is technically a microwave transmitter and receiver, designed to detect all transistors, diodes and other semiconductor devices which are found in transmitters, tape recorders, electret microphones and other eavesdropping devices.

The NLJD is the only type of instrumentation that can successfully detect all radio transmitters, regardless of their transmission frequency, even if its battery is no longer active.

Without the NLJD, the TSCM service would be unable to detect tape recorders, hidden electret microphones, remotely controlled transmitters, ultrasonic, infrared or microwave transmitters and other hidden devices which may be embedded in the walls or furniture and possibly beyond the detection capability of other test equipment.

Recognized manufacturers are Information Security Associates (ISA), Research Electronics International (REI), and AudioTel. These devices range in price from $16,000 to 30,000.

To learn more about specialized TSCM equipment you can view a 20 minute clip from the independent video production called The Red Balloon. The video requires a broadband Internet connection - Click here to view.