COUNTER SURVEILLANCE DETECTION - A SECOND LOOK
by Alan L. Susal

We are monitored daily by surveillance devices that are scanning us. We welcome the security afforded by some of this surveillance (identifying bank-robbers), may feel ambivalent about other applications (recording traffic violations) and feel downright hostile toward surveillance, which infringes on our personal privacy (covert cameras in hotel rooms and restrooms). In the world of business and government, covert surveillance can reverse a company’s competitive edge, tip-off antagonists to critical design and strategy, threaten lives and even change the course of history.

It is the responsibility of security personnel to protect companies, governments and individuals from such intrusive surveillance. The counter-surveillance professional has a whole host of sophisticated equipment to accomplish this task: specially calibrated amplifiers, custom detectors, spectrum analyzers, data decoders and recorders, customized computers, oscilloscopes, frequency counters, broadband receivers, etc. This equipment is big, heavy, bulky and expensive. Such an array of equipment is often beyond the means and expertise of a potential security officer or counter-surveillance person.

The recent availability of high frequency IC’s designed for use in cell phones and wireless communication devices have enabled the development of new ultra-sensitive counter-surveillance instrumentation. These new instruments are small, portable, broadband, and uniquely effective in detecting and locating covert transmitting devices. They save time and frustration, and are surprisingly affordable as well. Alan Broadband, in early 2003, has introduced the second in a series of such instruments – the Zap Checker Model 270 (ZC 270).

Zap Checker 270 with optional antenna

The Zap Checker Model 270 is a radio frequency field detector with the ability to detect very weak signals (down to ambient levels of radiation that exist around us. The ambient radiation level is usually due to local FM and TV broadcasts.) The ZC 270 detects signals spanning the microwave, UHF, VHF and high frequency spectrum, covering a 10 MHz to 4.5 GHz bandwidth. This includes 3.5, 2.4 and 1.2 GHz covert cameras and bugs, 2.4, 1.8, and 0.9 GHz cell phones and wireless phones; 300-400 MHz walkie-talkies, car keys and garage door openers; 70-150 MHz FM transmission; 49 MHz bugs and even 27 MHz citizen-band transmissions. Detection at 2.4 GHz is so sensitive; it will detect an operating “sealed” microwave oven at 12 to 15 meters away and pick-up 2.4 GHz covert transmitting bugs at 8+ meters distance.

How does the Zap Checker 270 differ from the earlier, lower cost Zap Checker 180 (U.S. $89.00)? It differs in a number of ways as listed below:

1) A more sensitive pre-amplifier with greater high frequency gain.

2) A newly designed printed circuit board.

3) 2 enhanced internal antennas – a high frequency and lower frequency antenna – neither requiring any adjustment.

4) A wider-range and adjustable sensitivity controller (26 db variable attenuator).

5) A 3-Position Gain Function Switch that switches between:

• High sensitivity LINEAR detection (10 db of the weakest signals detected).
  
  
• Wide dynamic range LOG arithmic detection (60 dB, 1,000:1 signal strength detection).
  
  
• A MID range detection mode with good sensitivity and intermediate dynamic range.

BUT MOST IMPORTANT OF ALL:

6) It has an electronically switched input - toggled between the 2 fixed internal antennas or a SMA input connector.

7) It has a female SMA coaxial input connector (50 ohm impedance, dc. isolated) that enables the use of various directive, frequency-specific antennas, filters or attenuators.

8) It has an optional 1.8 – 6.4 GHz LOG PERIODIC ANTENNA.

The Zap Checker 270 is similar to the Zap Checker 180 in that both have the following attributes:

1. An Analog Meter Display.
   
   
2. An intensity-modulated 2 color LED display that indicates the level of the detected signal from a distance or at nighttime.
   
   
3. An intensity-modulated silent vibrator that provides variable vibration intensity depending upon the signal strength.
   
   
4. Long operation using 2 AA alkaline batteries (60 hours).
   
   
5. A freestanding upright design that enables the meter and LEDs to be viewed from a distance.
   
   
6. Portability, weighing 150 gm with batteries installed.

The unique feature of the Zap Checker 270 is the ability to use special antennas, band pass filters and attenuators through the SMA coaxial input. Depending upon the frequency and directionality of the externally connected antenna, the ZC 270 becomes a highly directional frequency-specific instrument, which is ideal for counter-surveillance detection.

The optional 1.8 – 6.4 GHz Log-Periodic Antenna available with the ZC 270 boosts the sensitivity by 3 times. It also narrows the directional detection characteristics of the ZC 270 to a longer, thin scan pattern directed along the long axis of the antenna. With prior instrumentation it was necessary to “sweep” a room by moving the detection device from 30 to 70 cm away from the walls, ceiling and floor in a raster-scanning mode, similar to the travel of an electron-beam in a television CRT. That is time consuming and back-straining work! Using the Zap Checker 270 with antenna, the covert device can be initially detected from 8+ meters away. That’s outside the room or at the door. Then, from the door itself, the walls, ceiling and floor can be scanned by pointing the directional antenna and hand sweeping the room. Now we can “SWEEP THE ROOM FROM THE DOOR”, detecting the direction of the covert transmitter from a distance.

Optional 1.8-6.4 GHz Log Periodic Antenna

Once the direction of the covert device is detected, we move closer to it while decreasing the gain using the sensitivity controller, keeping the signal measurement within the limits of the meter scale. When we are so close that the meter reading is constantly at the highest level, we reset the ZC 270 to a wider dynamic range by switching to the LOG detection mode. In the LOG mode it is possible to pinpoint the bug up to a few cm away without overwhelming the instrument by the high signal level at such close proximity. If the signal is too strong, use the SMA connector to screw on an external attenuator in series between the antenna and the ZC 270. Use as many attenuators as necessary to control the signal level for accurate detection. Now we can identify that tiny hole in the wall as the pinpoint opening to a covet camera or microphone!

The frequency specificity and directionality of the ZC 270 is controlled by the external antenna connected to its SMA input. The optional LOG Periodic Antenna works well in this manner. Using a ½ meter 2.4 GHz loop-yagi antenna improves the sensitivity 6 fold at 2.4 GHz and narrows the detection width to about 5 degrees. The ZC 270 can be directly connected to such antennas or connected using a flexible cable. It is also possible to use patch antennas of different frequencies on the ZC 270. Avoid measuring transmitted signals which are directly connected to the SMA input. The signal levels of such devices can be large enough to damage the sensitive receiver input of the ZC 270.

Band pass filtering is accomplished by connecting band pass filters in series with the antenna. This confines ZC 270 detection to a particular band within its 10 MHz to 4.5 GHz range. Such band pass filters are available from sources such as Mini Circuits. Directional antennas usually have increased sensitivity along their longer axis. Pointing the front of the antenna towards the transmitting device gives the strongest pickup – but there is also an enhanced pickup 180 degrees away from that direction to the rear of the antenna. The differences between the front and rear sensitivities are usually specified by the front to back ratio in dB. More directional antennas, (usually longer in length), tend to have higher front to back ratios. When specifying the direction of the signal source, be aware of the diminished signal enhancement directed from the rear of the antenna.

ZC 270 with directional 2.4 GHz loop Yagi antenna

The Zap Checker 270 is an extremely sensitive instrument which detects signals that are coupled to it in any manner. In this way the ZC 270 is more like a wideband receiver with an antenna input. The proximity to a metal cabinet, desk, or automobile can affect the reading. Also, the proximity of your hand or body may increase the reading, acting as the antenna and coupling a stronger signal to the input. It is even possible to reflect signals directed toward your body and redirect them to the ZC 270.  Be aware that although an external antenna is optimized to enhance reception within a particular band of frequencies, it is also capable of detecting stronger signals from out-of-band frequencies.

When initially using the ZC 270, it is often perplexing why detected signals appear so fickle. By moving closer to the window, the signal strength increases (the walls of the room tend to shield the outside signals). The walls of the room define a resonant cavity – the room itself.  Radio waves bounce off the walls, ceiling and floor to give enhanced “hot” spots (where the signals converge) or “cold” spots which are devoid of signals. Different frequencies have their own hot and cold spots. When moving the ZC 270 just a few cm the detected signals may change dramatically due to these intensified and rarefied signal regions.

Polarization effects may also be apparent with the ZC 270, especially when an external antenna is used. Polarization effects are noted when rotating the antenna from a horizontal to a vertical plane. The change in signal strength gives an indication of the polarization of the transmitting source. It is even possible to note changes in signal intensity in outdoor wide-open spaces. Buildings, trees, people, mountains, etc. all reflect signals that produce variations in signal strength. It is important to consider these other factors when detecting and locating weak covert signals. Experience with use will overcome many of the hurdles.

There are some uses for the ZC 270 that do not relate to the detection of covert devices. For example, the ZC 270 is ideal for detecting and locating interfering transmissions during commercial airline flights. From the far end of the flight cabin a crew member can detect cell phones, laptop computers, PDAs, games, entertainment devices, etc., broadcasting interfering signals that can compromise aircraft communications and navigation. Using the LOG mode a crew member can specifically locate the offending signal source, and demonstrate that fact to the passenger. Since the ZC 270 is solely a receiving device (containing no local oscillator), it does not emit any signals, making it safe for aircraft use.

The Zap Checker 270 also speeds up and simplifies the installation of wireless devices – from security cameras to wireless computer networks. With wireless installations the ZC 270 verifies the signal strength of the transmitting device. It identifies the hot and cold spots in the region. Hot and cold spots are usually undesirable as transmitters or receiver sites. It measures the baseline level of RF at these sites and detects any interfering signals (RFI) that may occur. Besides detecting the RFI, the ZC 270 also can identify its source.

Zap Checker products are used in operating rooms by bioengineers to identify RFI interfering sources during open-heart surgeries.

The ZC 270 with directional antenna optimizes the radio link between a wireless transmitter and receiver. It is also helpful in selecting a hub site for solid communication with its multiple secondary WLAN sites.

Corporate security officers use the Zap Checker to identify potential hacker-sites outside their facilities and to help shield and position wireless transmitters to eliminate those hacker-sites.

The Zap Checker 270 is instrumental in identifying radio frequency interference sources from coronas and arcing insulators on utility poles. By using a directional antenna on the ZC 270 an offending insulator can be located from the ground. This enables utility personnel to quickly and easily identify the problem from a safe distance. (Even bolts of lightning are detected by this instrument.)

Following are some of the specifications of the Zap Checker 270:

1. High sensitivity – with a maximum sensitivity of 100 uV  (to detect RF signals down to ambient, baseline levels.)
   
   
2. 10 MHz to 4.5 GHz broad frequency spectrum.
   
   
3. Manual/electronic switching between antenna inputs.
   
   
4. 2 internal, fixed antennas that do not require any adjustments.
   
   
5. A switch-selected SMA antenna input - 50-ohm impedance, dc isolated.
   
   
6. An adjustable sensitivity knob  – 26 dB variable attenuator.
   
   
7. 3 detection modes:
   
   a) Linear – displaying 10 dB of the weakest signals.
   b) LOG – displaying 60 dB of signal strengths.
   c) MID – intermediate sensitivity and dynamic range.
   
   
8. 2 Display Modes – An Analog meter and colored LED’s (which are readable from a distance and at nighttime).
   
   
9. A switch-enabled silent vibrator - with vibrations modulated by the signal strength.
   
   
10. An optional 1.8 – 6.4 GHz Log Periodic antenna with SMA connector.

Alan Broadband Company offers the Zap Checker 270 for U.S. $369.00, including the LOG Periodic Antenna or U.S. $269.00, without the antenna. Orders are taken by telephone, mail, or fax at the following location:

Alan Broadband Co.
93 Arch Street
Redwood City, CA  94062, U.S.A.

Tel:
Fax:

E-mail:
Website: www.zapchecker.com     

To view our articles 'Counter Surveillance Detection - A Primer' please click here and to view 'Surveillance - Straight Talk' please click here.