How to find hidden camera – Detecting video transmission

In majority of the cases the striker is not able to fix any signal cable that can transfer the video signals from the camera to his/her screen. There are others methods of transmission that are more specified to the striker’s requirements than plain video cables which take more time to fix. In this portion, methods for transmitting video signals and procedures for their detection will be discussed.

IRF transmission:

The classic method to transfer the video signals is the use of modulated radio frequency. Radio frequency video transmitter can be detected with special equipments such as spectrum examiner.  Spectrum examiner statistically shows a frequency vs. signal chart. It is possible to get the frequency of the signal from the data given in the chart. Video signals have various features. The modern video signal has a brand width of 5 MHz, a line frequency of 15 KHz and horizontal frequencies of 20 Hz. Analysis can be difficult if the signal is communicated digitally or if frequency boosts methods are used. Example includes the spread spectrum method which marks transmission as normal voice.  In this case more experienced equipments such as vector signal examiners are required.

 A video counter measure device consists of a flashing light bulb.  The basic theme is to constrain a camera to produce the video signals of known attributes.  The radio frequency emitted by the video equipment can be determined by scanning the radio frequency bands for signal that match those attributes.  The modern video links that are available from most accessible dealers can be detected very easily. Most transmitters work at 2 MHz band and use one out of five freely usable channels.

 Wire bound transmissions:

Wireless transmission is the only way to transfer the video signals without fixing any additional wires.  The video signals can also be transferred with the help of unused electric or telephone cables. Even though power cabling is by no means adjusted to the impedance of the video signals; it is possible to transfer the signal from some distance. In an experiment, a video signal was fed into an inactive extension cord of fifteen meters length.  At the remote end of the extension the video signal provided an image of good quality. In fact the quality cannot be expected to fulfill the broadcast standards, the signal still can be used efficiently. With a common amplifier, distances up to 1400 meters can be gained with twisted pair wire and up to 600 meters with the help of a telephone cable.  Baseband conveyance can be hard if no unused wire is available.  In this case, the striker may adjust a carrier with a video signal and feed this signal into the electric wiring.  This method is known as carrier current transmission and is used by most wired baby phones.

Optical video links:

 As a substituent the video signals may be transferred optically with the help of an infrared transmitter.  This can also work in the presence of visible light, but this is seldom done because these visible junctions are easily detected. The emitter may use a semi conductor beam or a group of infrared LEDs. Optical video links cannot be found by the normal radio frequency detection devices except for the local emissions.  Since infrared radiations cannot be detected by the human vision so additional equipments such as infrared sensitive CCD or CMOS cameras are needed to detect the IR radiations.  For sharply focused transmitters it is necessary that the camera faces the emitter, otherwise smoke should be used as a reflector to make the infrared beam visible.  Please note, that the striker’s receiver also requires facing the transmitter. Detailed examination of any discovered infrared radiation is possible with infrared sensors paired to signal analysis device.


Communication networks:

The video signal can also be transmitted with the help of communication networks.  Examples include analog and ISDN phone lines, cell phone networks and computer networking. Information may be inserted in those networks by taking over the dupe owned cameras that are connected to the networked equipments. Instead of getting control over networked equipment that is owned by the victim, the striker may select to fix additional micro computers, that the victim is not aware of.   These micro computers can be small, implanted for special purposes.  Examples are the special webcam servers that involve heap and Ethernet interface. If the internet protocol traffic is contemplated too obvious, as a substituent a video signals may be transferred at the Ethernet end.  Another example is the video torrent servers that can be fixed to ISDN networks.  The clear procedure for finding video signals transferred on regular communication networks is to inspect all the networks.  This will find the plain video transmissions, but will be unable to find the data disguised as harmless data.  As an example the striker may create a workstation to capture webcam images.  The captured images could be transferred in different pieces by altering the mail IDs. If the striker can snuffle the outgoing data, so up to some extent he/she will be able to merge the data to get a complete picture.           

Detecting the camera’s emission:

Majority of the cameras release a typical spectrum of electromagnetic radiations.  This spectrum mostly results from the pixel record signal and parts of the video signals.  The emitted spectrum is identical for most cameras that can produce a standard video signal.  It is possible to find electronic cameras by scanning for this spectrum. Relying on the frequencies of the signal parts, suitable protection may foil the detection attempts, but usually cameras are not shielded at all.

Detecting the line frequency signal:

The essential part of any video signal spectrum is the line frequency. The line frequency is identified at the time on which the sync pulse is generated.  The line frequency for the standard signals is 15 kHz.  The accurate value is 14.652 kHz for CCR signals and 14.750 kHz for the NTC video signals. It is released at smaller ends by the video cameras and wires. Insufficiently protected cameras can be detected by means of VLC receivers.  Simple home use VLCs are available at some spy devices shop.  They are easy to use, but they are very costly and not very flexible. Basic very low frequency receivers are simple in design.  The procedure for the very low frequency receivers can be explained in this experiment. For the signal analysis, a 40 KHz computer sound card and spectrum examining software was used. Relying on the space between the camera and the very low frequency antenna, a peak at the line frequency can be seen on the spectrum table. Various pickup foils were tried as antenna.  Experiment with a foil of length 3 cm showed encouraging results.  The space at which the camera could be located was enhanced up to three times by using a resonant coil wound on a ferrite rod. Table 2 shows the distances at which several devices can be found.  The ferrite rod was used as a pickup foil.  The distances are the traditional utilities in which the 15 KHz peak could be found without any uncertainty. Also consider that the pickup coil is a non-optimized experimental version. With the use of professional devices it is easy to detect the cameras at greater distances.

Table 2:

Camcorder: 80 cm

Camcorder protected (one layer 0.01mm coil):  60 cm

Camcorder protected (two layers 0.01mm coil):   55 cm

CCD camera:  10 cm

CCD camera one layer foil:  8 cm

CCD camera power cable (unprotected): 10 cm

CCD camera video cable:  8 cm

CMOS camera:  3 cm

Table 2 reveals that protecting can have some effects if it is carried out properly. There is a remarkable variation relating to the emissions that result from the video cables. By using the RG -55 and 70 cable no emissions can be noticed. In contrary, the video cables with small length can produce strong emissions. The unprotected power cable released signal of parallel durability. The signals released by the CMOS camera are too weak that they cannot be seen in the daily life.  The very low frequency receivers do not find out the cameras, they can only detect the video signals generated by the cameras. In general, very low frequency receivers can detect the TVs and improperly protected cables that transfer the video signals. This could be considered as a positive and negative point as well. The edge is that, the very low frequency receivers can not only find out the cameras, but also the wires used by the attacker. This is particularly effective where the striker uses the pre-installed unprotected wires such as telephone cables for transferring the video signal to the outside.

Detecting thermal emissions:

In most of the electronic equipments, at least one aspect is common: they get heated because of losses along the conductors. After some time the equipment is heated up enough to release a thermal spectrum that can be detected by suited thermal imagers.  This is particularly useful for the CCD cameras because they have high power consumption and as a result high thermal losses.  Telebrands associates showed a procedure called TESA. They used a sensitive thermal imager that can find thermal variations as low as 0.1 degree.  The TESA appears identical to a normal video camera. The difference is that thermal imager will show images that emit thermal energy as shining spots.  In contrary to the procedures that depends on various electronic emissions, this method is not easily deceived if the camera is powered off as soon as a bug sweep is suspected.  This is because the device and the attached materials will remain its high temperature long enough to be observed by the TESA devices.  It is unknown whether the TESA scan will locate the low power CMOS cameras or not.

Detection by means of a laser:

Science and engineering associates have proposed a device naming Spy finder. It consists of a pair of low power lasers with a wavelength of 640nm.  It functions optically using proprietary optics.  The camera looks like a flickering red light. This is declared that it can function against all types of cameras even when switched off within an area of 10-40 feet.  The device is further declared to locate the night version cameras also. A consumer version of this device is also available in the market.


Different places and methods that are commonly used for hiding the miniature cameras were presented in this article. Some technical aspects were also discussed. Although this article does not allows the reader to become a professional expert, but it gives some basic knowledge which can be used to detect simple surveillance attempts. Your feed back will be highly appreciated if you have gone through any experience of finding a camera by making use of this information. Just keep one thing in mind, that the basic step for finding a secret camera is suspicion. Conflicting to the common belief secret cameras is not rare. Do not agitate, but be aware of the potential threat. The micro hidden cameras in the coming decades will be smaller and thus it will be more difficult to locate them.   

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