ST131 PIRANHA-II multifunction detection device

Product Description

Multifunction detection device ST131 PIRANHA-II was designed for detection and localization of covert surveillance devices (CSD) used for surreptitious obtaining of information, as well as localization of natural and artificial sources of threats of information leakage. Technical capabilities and characteristics of the detector allow user to find almost all hazardous types of surveillance equipment, as well as define possible threats of data leakage. The detector has the best “price/capabilities” ratio among same class devices.

ST131N PIRANHA-II – the modification that includes option of non-linear junction detector for localization of surveillance devices which and are connected to an analyzing wire. Almost all surveillance equipment contains semiconductors (transistors, diodes and etc.) that are normally used as part of power supply for overvoltage protection. The operating principle is based on generation of stable sinewave signal into the wire and analysis of returned at a harmonic multiples frequency level signal. The presence of 3rd harmonic frequencies is a reflection of the fact that semiconductor is connected.

ST131 can detect:

Covert surveillance devices which transfer information by radio channel, including:

  • Radio microphones as well as devices with storage and subsequent transfer of information (burst transmitter) and Frequency Hopping Spread Spectrum (FHSS)
  • Telephone radio broadcasting devices
  • Radio stethoscopes
  • Wireless video cameras
  • Unauthorized mobile phones and modems of CDMA, GSM, UMTS, DECT standards
  • Devices which use digital channels of data transmission (WLAN and BLUETOOTH)
  • Radio beacons for object movement tracking
  • The CSD which use AC power, telephone, security and fire alarm lines for information transfer
  • The CSD which use infra-red range for information transmission
  • The CSD which use ultrasonic frequency range for information transmission

Natural and artificial sources of threats of information leakage, including:

  • Mechanical vibrations that were transformed into an electrical signal which can be transmitted through wire lines (AC power, telephone, security, fire alarm and etc.).
  • Places of high possibility of acoustic and vibroacoustic information leakage due to weak noise insulation.


Main unit

st1311_1 1. Receiving-transmitting and control socket in RADIO channel as well as for connection of SHF and infrared detectors.
2. Socket for connection of transducers operating in ACOUSTIC channel and Magnetic Field Probe
3. Socket for connection additional Probes
4. Socket for connection of UHF convertor (RADIO channel) and wire line adapter (WIRE LINE channel)
5. Valcoder

st131_3 1. Line Out
2. “3.5” socket for connection of headphones
3. Volume
4. Battery compartment covers.
5. Power ON/OFF
6. Power supply socket
7. USB socket

st1311_3 1. “+” and “” increase/decrease of display brightness level and switching between the bands
2. “SET” entry in main MENU
3. “INFO” – entry in the current settings indication of the device
Purpose of the context buttons F1 – F5 indicated in the lower line of the display depends on
the selected detecting channel and operating mode in this channel.
Full“- switching on the mode FULL RANGE
BND” – switching on the mode BAND
DMD” – switching on the mode DEMODULATION
L” – switching on the sub-mode SCALE
MEA” – access to measuring function
6. “М” – switching in sub-mode MEMORY
7. “А” – switching in sub-mode AUTOMATIC ANALYZING
8. “><” – manual selection of noise level relative to zero value and movement of items in the MENU
9. “>0<” – automatic selection of noise level relative to zero value
10. “ENT” -enter (press VALCODER also equal to press Enter)
11. “0-9, .” – digital keyboard

Detection channels

The ST131 has 4 main detection channels:

RADIO channel is used to detect and analyze radio signals between 0.01 — 18000 MHz. The device set includes variety of different antennas which enables user to work in 3 different frequency bands: LF-MF-HF (0.01 — 30 MHz)
VHF-UHF (30 — 4200 MHz)
SHF (4000 — 18000 MHz)

WIRE LINE channel is used to detect and analyze the signals which are transmitted by different wire lines (power, telephone, coaxial, computer networks, security and fire alarm systems, etc.). The allowed voltage in the lines (DC or AC) is up to 250V. 3 different frequency bands are available: LF-MF-HF (0.01 — 30 MHz)
VHF-UHF (30 — 1000 MHz)
acoustic frequency (0.3 — 15 KHz)

OPTICAL channel is used to detect and analyze the radiations in the optical frequency range. The device set includes ST131.IF infrared detector is for operation in this channel. ST131.IF infrared detector

ACOUSTIC-ELECTRIC channel is used to receive amplify and analyze and signals within the frequency range between 10 Hz and 125 kHz. An Ultrasonic signal converts into an audio frequency signal by means of digital heterodyning. User is provided with different types of acoustic transducers depending on a task. Acoustic-electric channel
(0.01 — 125 KHz)



UHF converter is a downconverter of 30 MHz – 4400 MHz frequencies into the frequency range of WIRE LINE channel.

UHFNEW 1. TNC socket
2. Thread opening ¼”
3. Switching-on and battery discharge indicator
4. Indicator intensity of data exchange
5. Power switch ON/OFF
6. Battery compartment cover


In ST131AWL constructively combined:

  • Reducing the transformer voltage converter designed to operate in the frequency range of 0.01-30 MHz
  • Low-frequency differential amplifier designed for use in the acoustic frequency range (0.3-15 KHz).
  • Switching unit controlled directly from the main unit and provides the necessary connection of pairs of contacts of the RJ-45. Connection is made as to the most common combinations of pairs and arbitrary, user-defined option.

Connecting to a study done through the line:

  • Connector RJ-45 (3) provide connection to ETHERNET and a telephone line with software, if necessary, pass-through connection.
  • Connectors for connecting test leads (1) that provide connection to other types of wire lines with clips such as “Crocodile”.

After selecting a channel “wired” and pressed the button «COMM» of options provided by the commutation of pairs of contacts are connected to the RJ-45 connector.
Combination of “4-5”, “3-6”, “1-2” and “7-8” are the most likely options are selected and pairs of priority.
Also provides access to the arbitrary choice of pairs (with the exception of the same name), change the polarity and detach from the investigated line.

For attachment to the supplier and holder of the shoulder of the main unit includes a magnet holder and a special slot.

1. Bananas socket
2. Ground connector
3. RJ-45 socket
4. Indicators of voltage in Line (LINE)
5. Indicator of overload of signals (OVERLOAD)
6. Indicator of power supply and link with the main unit (PWR/LINK)


st131rawl ST131.RAWL is intended to operate the WIRE LINE channel in the frequency range of 30 – 1000 MHz.
It has installed components that protects against failure of the input circuits of the UHF converter.
The adapter connects to a single-type connector «SMA» of the UHF converter ST131.UHF.
Input connector type “F” is designed for direct connection to the coaxial lines.
To connect to the lines with BNC type connector use an adapter «BNC-F».


The Probe is a device combines receiving photodiode and pre-amplifier.

st131_ir_tmb 1. Infrared probe
2. Socket
3. There thread is used for connecting to turning mechanism of the SPECIAL HOLDER.


The HOLDER is intended for facilitation of search of IR transmitting devices those installed at external side of the window in the direction “from the window”.

st131_shtativ_tmb 1. Handle
2. Four sections total length of 900 mm.
3. Turning mechanism


ST131.SHF consists of the log-periodic antenna and SHF detector-amplifier which are integrated in one body.

st131_svch_tmb 1. Handle
2. Log-periodic antenna


ST131.MF consist of the ferrite antenna (FA) which is placed in the upper part of the detector, pre-amplifier and a handle with integrated battery compartment.
ST131.MF operates in two modes – directly as a magnetic field intensity sensor and as a GRADIOMETER. When using GRADIOMETER mode, influence of remote sources of magnetic field is reduced significantly.

st131_md_tmb MAG/GRAD Mode select


ST131.UHF.A is a broadband passive antenna.

antenna2 1. TNC socket
2. Аntenna


The Testing device “ST131.TEST” is intended to control operability of the multifunction detection devices ST131 PIRANHA II and ST131N. Using this device allows to check all of detection channels.
The main unit is a complete unit that provides creation and emission of test signals as well as non-linear junction to check the nonlinear detector.

frontback 1. Battery charge indicator
2. Power supply connector “5V”
3. Power switch
4. Connector “CH2” – output of signals to check the ACOUSTOELECTRIC channel.
5. Connector “UHF” – output of signals to check the “RADIO 30-4100” channel.
6. Rotary knob
7. Installation site for ST131.SHF
8. Installation site for ST131.MF
8. Installation site for ST131.IR
9. Connector “AWL” – output of signals to check the WIRE LINE channel.



FULL RANGE MODE is intended in general case for visual estimation of the occupancy level of the selected channel and making decision related to transfer to:

  • Analysis of the specific frequencies using automatic signal detection option “AUTOMATIC ANALYSIS”.
  • Detailed investigation of the segments of the range (“BAND” mode).

BAND mode can be used for detailed visual and audio analysis of the signals within selected band.

DEMODULATION MODE is used mainly for audio control of the demodulated signal.



SCALE sub-mode is used for representation of signal in the form of multi-segment scale with numerical values of the signal level. SCALE is the most required option to localize of the CSD.

AUTOMATIC ANALYZING sub-mode is used for automatic detection of the signals, which level of exceeds the level set by the user.

MEMORY sub-mode is used for storage of the screen image in the memory of the device. Indication of the stored image is provided in the screen of the device.

MEASUREMENT sub-mode is used for providing absolute and relative measurements of signals.



OSCILLOSCOPE option to analyze the signals in time domain.

SPECTRAL SUBTRACTION option for indication of the results of the spectrum subtraction. This is achieved in two ways:

  • The spectrum which was memorized temporarily at the moment of turning on this mode is subtracted from the new measured spectrums.
  • The spectrum which was stored in the memory before is subtracted from the new measured spectrums.

DIGIT option is used for searching of the radio transmitters with digital standards of data transfer and measurement of the signal level of corresponding base stations.

NON-LINEAR JUNCTION DETECTOR option (only for ST131N) is used for localization of surveillance devices which and are connected to an analyzing wire.


Product specifications


Simultaneous processing frequency range 0.01 – 30 MHz
Resolution ADC 10, 14, 16 bit
Number of FFT points 32768 (PC mode), 512 (main unit)
Bandwidth 0.0005 – 10 MHz
Demodulation types AM, FM, SSB, TV (AV)


Frequency range 1 Digital signal processing module 0.01 – 30 MHz
Displayed noise level Within the whole bandwidth -110 dBm
Within DDC bandwidth 1 kHz -150 dBm
Value of the possible bandwidth, MHz 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01, 0.005, 0.002, 0.001, 0.0005
Frequency range 2 UHF converter 30 – 4400 MHz
Displayed noise level Within the whole bandwidth -110 dBm (PC mode), -90 dBm (main unit)
Within DDC bandwidth 1 kHz – 130dBm
Input signal max level 5 dBm
Sweep speed max 10 GHz/sec
Value of the possible bandwidth, MHz 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01, 0.005, 0.002, 0.001, 0.0005
Identified data transfer standards CDMA, GSM, 3G,4G, WLAN, BLUETOOTH, DECT
Frequency range 3 SHF Detector ST131.SHF 4000 – 18000 MHz
Threshold sensitivity -65 W/cm2
Antenna beamwidth 60-90 grad


Frequency range 1 0.01 – 30 MHz
Displayed noise level in full range – 90 (120 for PC mode) dBm
at 1 kHz band for Main Unit -125 dBm
Input signal max level 20 dBm
Max permitted input voltage 380V
Value of bandwidth IF, kHz 6800, 2500, 630, 150, 75, 40, 10, 5, 1 e` 0.5
Gain input amplifier -5, 1, 7, 13, 19, 25, 31, A`KG
Frequency range 2 0.3 – 15 KHz
Displayed noise level in full range, not worse -115 (140 for PC mode) dBm
Input signal max level 20 dBm
Gain input amplifier 14, 26, 38, 44, 50, 56, AKG
Common-mode interference attenuation factor 60 dB
Max permitted input voltage 250V
Frequency range 3 30 – 3000 MHz


Dynamic range 60 dB
Frequency range 0.01-30 Mhz
Spectral range 770-1600 nm
Angle of sight 30 grad
Wire length 1.5


Frequency range 0.01 – 125 KHz
Displayed noise level in full range -100 (148 for PC) dBm
at 1 kHz band for Main Unit -120 dBm
Input signal max level -5 dBm
Gain input amplifier 6, 14,20, 26, 34 e` 40
Frequency range 30 – 30000 Hz
Transformation ratio (1000Hz) 1.00±0.01 B*m/A
Threshold sensitivity, less than 2*10(-6) A/m*Hz(1/2)


Frequency of test signal 150-220 kHz


Dimensions 190x97x50 mm
Indication 3.5” 240×320, TFT 262144 colors
Interface USB 2.0, 200 Mbit/s
Power supply 6 AA batteries (rechargeable batteries)