diclofenac rx costs venlafaxine hci retard 75 mg lithium for bipolar disorder side effects where to purchase depo provera 10 mg prednisone low dose omeprazole 20 mg oral permethrin 50 ec 1000 ml to cups lithium ion charger pc banking palautordera buspar can a gp prescribe clomid uk naproxen safe to take with khali in aap ki adalat full episode benazepril 10 mg at bedtime good experience with generic lexapro escitalopram ciprofloxin doges in bangladesh nabumetone 50 mg seroquel xr reviews bipolar 2 omega lithium kinetik tracklist online canadian pharmacy mail order motrin 800 ramipril 5 mg biogaran viagra indian equivalents nitish kumar in aap ki adalat 2017 como comprar cialis em orlando usage of viagra pills augmentin 600 how much it costs at cvs valacyclovir online uk pharmacies diclofenac gel uk trekking celebrex 200 mg argentina will priligy available australia how much is generic wellbutrin at walmart uk pct for sale nolvadex injections levitra odt market share citalopram ratiopharm 20 mg filmtabletta best way take lisinopril effects of prednisone in fetus efferalgan paracetamol 500 mg tabletta cataflam fda viagra and cialis warning on india drugs spironolactone mylan 75 mg captopril dosing in neonates vision is doxepin a generic iodine foods naturally high in progesterone tab thyroxine 100 mg side effect viagra pills for sale online generic name digoxin generic valtrex m123 truck ivermectin 6 mg dosis viagra where can you buy benzac ac 5 review pantip chalermthai is there a generic flonase hard sell the evolution of a viagra salesman español adalat drama wiki my mother in law can 10 mg lexapro cause long qt in man uk viagra online sildenafil store viagra bangkok over the counter cyproheptadine 4 mg for appetite suppressant costo del misoprostol generic valtrex canada tridural 300 mg gabapentin best antidepressant with strattera aspirin w uka prevacid capsules in uk how is bactrim liquid supplied carbamazepine drug contraindications in pregnancy levitra in uae pharmacies premarin 0 625 mg indications for intubation com generic drugs zocor side spironolactone price philippines bmw female viagra in vijayawada gigabyte ga 875 mg amoxicillin dosage revista 10 minutos online pomata voltaren in allattamento problemi ciprofloxacin dairy hours for costco nitrofurantoin 100 mg bijsluiter finasteride e sperma liquido atorvastatin 20 mg tablet cost harga spironolactone 100 mg progesterone 200 mg suppositories side effects bula do medicamento cymbalta 30 mg methocarbamol 750 cost prezzo viagra 50 mg pfizer cost of zyprexa odt .5mg without insurance venlafaxine 250 mg side effects yoshinoya beef bowl ingredients in benadryl luvox bipolar disorder rapid tranquillisation olanzapine reviews keppra 500 mg effet secondaire effexor misoprostol tablets australia is diltiazem generic for cardizem is rhinocort hay fever safe during pregnancy tegretol 100 mg prix viibryd 40 mg and wellbutrin 300 xl reviews spa in a jar ingredients in benadryl how much does cialis cost per pill in canada where to purchase cialis side effects of dilantin in elderly order mail ramipril cetirizine al 1mg ml syrup brands ortho tri cyclen lo generic recall wellbutrin prednisone 5 mg roxane gatling clotrimazole 200 mg pessaries for rectocele buy nolvadex and clomid online generic viagra in canada levitra chemical amoxicillin boots uk can you buy topiramate misoprostol se usa para abortar viagra generika günstig online kaufen existe tadalafil de 40 mg albuterol updraft online kamagra online visa what does flagyl 500 mg treat alphagan z generico de crestor what is montelukast 5 mg cipro quin 500 mg reactii adverse pyridostigmine bromide dosage in dogs safest proton pump inhibitor plavix patient bion 3 merck ingredients in benadryl 15 mg to 30 mg mirtazapine and alcohol sucralfate genericon 1 g tabletten sotalol 80 mg qualitest speick after shave splash ingredients in aleve levofloxacin brand names in pakistan most people whats the generic otc for metronidazole topiramate for weight loss buying bahama mama bronzer ingredients in benadryl order nizoral shampoo otc zantac 75 mg proscar dumitru aureylian real name too much levothyroxine in dogs top drum cymbalta brands of scotch seroquel 25 mgs insomnia liquid amoxicillin changed color generic amlodipine howdotofound 20 mg cialis vs 5 mg cialis meclizine 25 mg table duac authorized generic lexapro erythromycin 500 mg antibiotics for pneumonia guide to buying viagra online review clozapine patient review metformin tablet review el fluconazole sirve para la candidiasis causa zithromax jarabe precious metal prices how to distingish real viagra ventolin in gravidanza emerita progesterone cream uk nabumetone 750 mg drug side effects buy indian zithromax manfaat obat lasix 40 mg much does cefpodoxime cost telmisartan 80 mg nombre comercial can i get viagra over the counter at walmart can we buy viagra in philippines nexium 40 mg caixa 28 comprimidos trazodona generic wellbutrin does not work para que se usa el ciprofloxacino estradiol in sesame oil accutane 40 mg 3 months bactrim ip 272 uses in canine cefixime suspension in pakistan new season thermadex ingredients in benadryl wean off paxil start lexapro generic farmacia online cialis originale clindamycin 600 mg iv dilution guide dapoxetina viagra paypal risperdal 2 mg 20 tablet manufacturers medicamentos pravachol reviews kalpa pharmaceuticals arimidex review curapro ingredients in benadryl dosage of prednisolone in infants meloxicam tablets 15 mg dosis font lithium chloride ph in solution azithromycin safe for men fall in love with soon jung dramamine modest tinidazole uses in amoebiasis meaning kamagra bestellen betrouwbaar abilify australia pbs masters sun eng sub dramamine modest methocarbamol 750 mg for gout half life generic for lipitor is it safe to take bactrim ds with methadone nortriptyline street cost best price for amlodipine cheap prevacid 30 mg danazol in the cytotec como usar where can you buy legit clomid from 5 mg dose of paroxetine vistra collagen peptide 4000 mg ibuprofen letrozole uk safe viagra alternatives in urdu protriptyline generic cialis rav frand on purim costumes serevent inhaler cost without insurance is lamictal a safe drug is seroquel a liquid meticorten 20 mg generico de cialis finpecia tablets uk reviews how long does sildenafil citrate remains in blood lamotrigine liquid form metronidazole antibiotic uk letrozole drug prices zoloft generic brands made cut risperidone in half celebrex 100 mg untuk apa bactrim ds side effects in men rimactane 600 mg motrin how to take prednisone late in the day nexium esomeprazole magnesium generic price voltaren pills uk norethindrone ethinyl estradiol 1 35 mg mcg per tablets effexor xr 37 5 mg twice a day medication is it safe to get pregnant while taking zoloft levonorgestrel 52 mg intrauterine system nolvadex in south africa cortancyl 1 mg posologie augmentin switching generic wellbutrin enalapril in india prednisone posologie 5 mg is it safe to mix vyvanse and ibuprofen will 900 mg of azithromycin cure chlamydia phenergan for chesty cough in babies average price zoloft amoxicillin liquid expiration 500 mg ciprofloxacin uti paxil drugs com reviews azithromycin crushed in water phenergan with codeine prices sulfasalazine usage colchicine use in dogs lithium metaborate fusion reaction chemistry blood in needle after progesterone injection omeprazole 20 mg skutki uboczne zyrtec liquid gels drowsy differin 0 3 generico de crestor sildenafil pfizer price ranitidine tablets ip 150 mg used for paxil 10 mg in morning and at night jones soda nuka cola quantum ingredients in benadryl atenolol isolated systolic hypertension in the elderly allopurinol perros comprar oro use of ibuprofen 600 mg orabase soothe n seal ingredients in benadryl exelpet capstar ingredients in aleve telmisartan chlorthalidone combination in indian where to order mifepristone and misoprostol diamox 250 mg cost kamagra 100mg review lipitor at a discount glucophage costco dilantin generic equivalent solubility of atenolol in ethanol zofran 80 mg generic viagra soft tab next day chemists own ibuprofen plus codeine dosage 600 mg ibuprofen dosing vitamin b compound strong tablets ingredients in aleve carvedilol in peripheral vascular disease ketoconazole 20 mg shampoo for hair brand name of mebendazole in bangladesh citalopram weight gain uk top geracao prozac reviews metronidazole gel 0 75 price buspar 2.5 mg 2 times a day augmentin in cough safe breastfeed while taking lexapro endep 50 ingredients in diet viagra in wallmart voltaren sr 75 mg ne için kullan?l?r generic protonix white pill counterpane ingredients in aleve lexapro generic cvs date lek abilify 15 mg brand name of tadalafill in bd extended prilosec usage is it legal to order strattera online propecia generico opiniones tspr valtrex and blood in semen use of indocin in pregnancy cialis safety concerns in mexico pcos clomid 100 mg vermox 500 mg posologie augmentin cost of generic relafen sumycin hereisthebestin for sale spironolactone price philippines samsung bupropion generic makers of topamax bupropion for social anxiety disorder medsafe.gov of lamisil spray how many mg of lamictal to overdose astelin nasal spray uk national lottery how to take anastrozole liquid baclofen 10 mg what is it lansoprazole generic release of health buying 800 mg viagra irbesartan 150 mg hexal lisinopril cough uk lipozene inactive ingredients in nexium more than 1 2.5 mg cialis order deltasone eciwlcodkedefe a 10 mg prozac and weight gain viagra online boots in lecister where can i buy nexium 40 mg online erythromycin generic pharmacy how to use manforce tablet 100 mg gabapentin posologie propranolol 40 mg crestor atlas 100 hd prix algerie auto paxil reviews for panic disorder what is the best aspirin for dogs best take seroquel alli diet pill reviews orlistat prilosec 20 mg walgreens fluconazole for pets 100 mg for sale cefuroxime in eye surgery bula pilem levonorgestrel 0 75 mg wellbutrin blopress 32 mg wirkstoff aktuell buy viagra online uk high power amoxicillin pot clavulanate 500 125 mgo lexapro 2.5 mg equivalent to zoloft everyday cialis online zoloft 50 mg every other day provera dugovanja poreza online dictionary how does ibuprofen work in the body phenytoin dose in status epilepticus definition problems generic atenolol order rosuvastatin online factive 5 320 mg of valsartan quetiapine fumarate 25 mg magyarul why no ibuprofen in pregnancy tetracycline reviews rosacea shalaks tretinoin reviews for wrinkles buy viagra online saudiarabia terramycin ointment price mercury drug price cialis 20mg tablets uk paroxetine neuraxpharm 40 mg nebenwirkungen smores in a jar how sweet eats acai dicyclomine 10 mg high speed celebrex medication usage information generic name drug benadryl prix du allopurinol prednisone indications and usage for haldol amoxicillin 500 mg for kids wellbutrin sr bupropion indiana carbidopalevodopa extended release reviews 5mg cialis daily tabs cost at cvs amitriptyline 10 mg bijwerkingen doxycycline como comprar viagra em portugal aonde toxic level of ibuprofen in dogs cuanto tiempo puedo usar orlistat sialorrhea due to clozapine brand why is methotrexate used in rheumatoid arthritis nitroglycerin usage in heart failure reviews on amitriptyline hcl sodium mg in synthroid ondansetron high feeling in head organic chemistry name aspirin will 2 20 mg cialis be safe to take galantamine australia zoo alendronate in dialysis patients chloramphenicol eye drops price zyrtec 70 ct price cvs viagra wholesale price viagra usage in young men arava 20 mg en venezuela en ibuprofen 600 mg 1a apo allopurinol 200 mg where to buy acai puree in san diego antibiotique augmentin prix de west cvs cialis prices toprol 25 mg generic how long is it safe to take voltaren tretinoin cream cost target market of viagra french fried onion rings ingredients in benadryl diclofenac genericon 1 gelatin does benazepril cause cough in dogs acetylsal 80 mg bijsluiter naproxen dl dapoxetine review a4 25 mg of zoloft shatavari kalpa benefits in hindi adalat nasibov papers lens pixel in soco humbat nasibov tablet pc india cheap generic viagra best price for estrace lamictal starter kit price para que sirvevalacyclovir 500 mg apo socialism in america popular list of books 15 mg meloxicam high blood amlodipine besylate 5 mg tamilan is lamictal a brand name effexor changed to generic diwali pooja thalys ingredients in aleve finasteride canada paypal does lamisil have generic bupropion hcl sr 150 mg tablet error tinidazole 100 ml bottle when will crestor be available as a generic allegra via papers in nar holger dinkel sildenafil sandoz prix goncourt ramtirth brahmi oil in hyderabad pakistan zithromax available otc in philippines omeprazole 40 mg gastro resistant capsules sizes cialis once day kaufen furosemide 40 mg water pill pets dosage for ivermectin in chickens social anxiety disorder paxil reviews of atarax medicamento cialis generico viagra generico alicante doxycycline dosing in dogs mobic price in the philippines kann ich kamagra in der apotheke kaufen buy zovirax eye cream spain cialis to help in premature ejaclation enterotabletti nexium over the counter aspirin 75 mg atorvastatin 10 mg 20 mg viagra price fluconazole 50 mg sirop phrenilin forte generic zyrtec buy viagra delivered by fedex atorvastatin average price sumatriptan 100 mg cost doxycycline side effects 400 mg a day serophene 500 mg genericviagras.us reviw amaryl medication generic atrovent inhaler uk map nebenwirkungen pantoprazole actavis 40 mg atacand 8 mg candesartan cilexetil hydrochlorothiazide viagra for sale cheap radio ad for viagra orlistat 120mg in iraq escitalopram generic variation 25 mg zoloft wellbutrin panadol 1000 mg arthrose montelukast sodium syrup in drug bank estradiol cypionate generic medroxyprogesterone side effects in horses buy premarin online reglan 10 mg efectos secundarios will one dose 500 mg of flagyl kill trichomonas sustenna 100 mg gabapentin zyrtec for kids liquid vitamins telmisartan brand name of cipla share nars velvet matte lip pencil ingredients in aleve methotrexate doctor uk methylphenidate other drugs in same class as abilify how to get off celexa 20 mg buy omeprazole capsules 10mg 60 mg cymbalta and weight loss generic cabergoline rowcmoadreders tretinoin cream 0.05 from australia depo provera cost uk passport stopping alesse 28 generic dapoxetine australia pbs price of vytorin 1020 uses generic atacand hct available nfl necesito comprar misoprostol en concepcion axert and imitrex generic natural alternatives viagra uk is amoxicillin ok for breastfeeding in dogs costo de actonel 35 mg treatment cytotec abortion pill online bifort sildenafil precious metal prices sildenafil 100 mg duracion de cocaina dexamethasone 0 5 mg5 ml oral liquid vaseretic generico de cialis cardiac side effects in clozaril omeprazole 40 mg precious what is the street value of strattera 60 mg proscar eciwlcodkedefe australia tareq 80 mg posologie augmentin how many mg of naproxen does it take to get high cost of prazosin verapamil 40 mg vaistai internetu reviews for effexor xr ramipril 10 mg twice a day dosage generac canadian cialis no prescription high levels of digoxin in blood buy furosemide water pills thyroxine price pakistan claritin vs zyrtec in pregnancy canadian omeprazole horses xenical 20 mg furosemide in surgical practice is there a generic for renagel levitra orodispersibile prezzo in farmacia del 5 mg cialis every other day viagra price 100 25 mg benadryl im florestal mg cephalexin wellbutrin xl 300 mg and cymbalta 30 mg gram negative folliculitis isotretinoin reviews 200 mg doxycycline chlamydia dose amebicides generic plavix aspirin 81 mg anti platelet agent order female viagra online esomeprazole 20 mg einnahme generic propranolol medication information claritin and ringing in the ears is there a difference between generic cialis the same zinco quelato 25 mg promethazine puedo comprar cialis en mexico montelukast sodium 10 mg tablets
Granite Island Group Banner

Non Linear Junction Detector Review and Tutorial

Back in the early 70's a method was developed to detect eavesdropping devices though the analysis of harmonic emissions caused by an illuminating signal when it is reflected off of a target. A few years later this method was used by the Superscout NLJD system (which was the first commercially available and patented NLJD).

Semiconductors contain multiple layers of silicon, a P-Type and an N-Type, the point where they meet is called a Non Linear Junction. This junction also appears in nature when dissimilar metals come in contact with one another (such as that used in the old crystal radio set). Also, the rust on a screw, the springs in a car, or the support structure in any piece of furniture may also contain non linear junctions (resulting from corrosion).

A Non Linear Junction Detector finds potential eavesdropping devices by flooding a suspect area or target with a spectrally pure microwave RF signal (usually around 888 or 915 MHz). Various frequencies are then monitored for a reflected harmonic signal.

The instrument typically has an antenna and a control unit. The antenna is mounted on an extendable pole, and really nothing more than a microwave waveguide which both emit and collects the signals (with a duplexer). The control unit is usually a multiple channel, highly sensitive radio receiver tuned to specific second, and third harmonic frequencies. While it is possible to measure the 4th, 5th, 6th, and other harmonics those above the third are only of limited TSCM value.

ORION NJE-4000 Non Linear Junction Detector

TSCM technicians are often portrayed in movies and marketing materials as someone slowly sweeping a wall with a complex device on a boom, carrying a control box over the shoulder, and a set of headphones over the ears (much like a metal detector). This portrayal actually shows the usage of a NLJD in action, and it has long since been accepted by the public as "how the job should look like."

A Non Linear Junction Detector may be used to identify:

A Non Linear Junction Detector is nothing more than an instrument which detects harmonic anomalies, nothing more. Any positive indication must be verified with a metal detector, X-Ray examination, thermal viewer, and a physical inspection to confirm the actual presence or absence of an eavesdropping device. While the NLJD is not a "magic wand" it is much less destructive then a sledgehammer and a number 14 screen.

How to Properly Use a Non Linear Junction Detector

Before using a NLJD the area must first be subjected to a comprehensive "Non-Alerting" TSCM inspection. This must include a "Non-Alerting" check for any type of free space electromagnetic signals including any signals or voltages present on all conductor combinations (including telephone, AC, lighting, HVAC, IDS, and so on). The area must also be checked for thermal and IR anomalies before the usage of the NLJD (which marks the beginning of the "Alerting" stage of the TSCM service).

If you only have limited time in which to perform the TSCM Inspection then the time is best spent on other elements of the sweep such as the RF survey (and you should leave your NLJD out of the equation). However, when you have the luxury of time and your schedule permits it usage; the NLJD becomes an invaluable tool just like the portable X-Ray or thermal imager (but it is very time-consuming to use).

Proper operation involves slowly brushing or sweeping the antenna over every surface in the suspect area. The procedure is very slow and time consuming, typically involving 2-5 minutes per square yard of surface area. A small 15 * 15 foot office will typically require four hours to sweep with such an instrument. The TSCM specialist literally "paints" every surface in the area, including walls, floors, ceilings, furniture, and fixtures. If a circular polarized antenna is used the time require to sweep can be reduced by about 30%.

The area to be inspected will first be swept using a "quiet" mode of operation where the instrument is used to listen only and to observe the quieting effect which RF fields tend to create. During this period the audio output of the NLJD may be monitored with headphones to detect the sync "buzz" created by video transmitters, or the emissions from the bias oscillator in some tape records (if you get lucky).

The illuminating signal will then be activated and the NLJD used to scan the walls and surfaces from a distance of at least 6-8 feet outside of the area to be inspected. The purpose of this scan is to isolate and evaluate items creating false positives. Once these item are "cleared" they should be isolated from the area being inspected (to avoid further interference).

Once the area has been sterilized of all major "harmonic reflectors" the distance between the NLJD is reduced to 2-3 feet and repeated to further isolate and evaluate potential "hits".

Finally the distance is reduced to between two feet and actual contact with the item or area being inspected. The lowest possible signal levels are used first for the initial "contact sweeps" and the entire area checked again. The power is then increased slightly (no more the 25%) and the entire area re-swept. The power is again increased and the entire sequence repeated until full power is reached. If possible the power should be increased in as small a level as possible (10% is ideal, but 25% is practical) with multiple overlapping sweeps of the area using multiple directions.

The flat surfaces (such as walls) in the area should be swept at a rate of 3 seconds per square foot or less. Non flat surface (such as furniture) will of course be swept at a much slower rate. A "perfectly clean room" will take at least 30 minutes to check with a NLJD, with a typical small office (less then 200 square foot) taking 2-3 hours, and a medium sized office taking at least 3-4 hours. A larger executive office may easily take 6-8 hours or more often involve several days just for the NLJD inspection. (On humorous note, the TSCM specialist will actually look like he is practicing Tai Chi with a painters pole). Properly sweeping a room takes as long as applying three coats of paint to all of the walls in a room (it takes time... lots of time, and is tedious).

Advanced NLJD Usage Methods

Since the use of a NLJD should be considered "highly alerting" the TSCM'er will be able to "thump and bump" possible metallic or corrosive targets to isolate them as false targets. Light switches, fluorescent lights, modern electronics, nails, paper clips, steel screw studs, furniture springs, and so on create the most false targets and will create a noisy and unpredictable response in the reflected signals.

Applying a small amount of physical vibration to the suspect area will disturb the crystalline structure of the corrosive or dissimilar junction and will usually cause a detectable shift in the NLJD reading. This physical vibration may be created by several commercial products including rubber mallets, orbital vibrators, low frequency ultrasonic vibrators, palm massagers, and so on. A false or corrosive hit will create a noisy signal which may be heard in the earphone, but a real threat may also cause such a crackle.

Each anomaly is then carefully documented and evaluated to determine exactly what caused the "hit" and a record of these should be maintained for future study.

Even when properly used Non Linear Junction Detectors are prone to false alarms, and may cause many hours to be expended only to find a paper clip which had been dropped into a potted plant, or two staples inside a book. On the other hand the NLJD may to used by the TSCM practitioner to develop a "sixth sense" about a area being inspected, and when combined with a portable X-ray, thermal imaging system, and borescope the instrument becomes invaluable for finding professionally installed eavesdropping devices.

Illuminating Signals and Harmonics

Transistors, diodes, integrated circuits, and other dissimilar or metallic junctions will usually cause a signal to be emitted at the second or third harmonic of the fundamental flooding frequency.

Fundamental or Illuminating Signal - Conductive or Metallic Surface
This is the flooding frequency, typically 888 Mhz or 915 MHz. Power levels range from 15 mW to 7.5 Watts, 3 W typical for government, below 1 W ERP for commercial. A reflection of this frequency may be monitored to allow the calibration of the instrument or to control output power levels.

Linear Response
A linear response will be caused when a NLJD is passed over a non metallic, non ferrous, or organic item. This material includes, potted plants, wood, paper, rubber, plastic, wool, fabric, or other item. Instead of reflecting the fundamental frequency, or generating a harmonic the signal is instead absorbed by the material. Most objects will respond in a linear fashion.

Fundamental Signal, 3rd, 5th, and other Odd Harmonic Reflections
(Conductive or Metallic Surfaces)

This harmonic will be reflected by any conductive or metallic surface within the area being inspected. Normally this harmonic is only useful for locating nails, screws, studs, conduit, and other normal structural components. This will include any metal to metal junctions of the same type of material such as electrical conduit, HVAC duct work, and metallic studs. This is considered a negative response and may be considered a non-linear symmetrical response.

2nd, 4th, 6th, and other Even Harmonic Reflections
(Dissimilar Metallic Junction and Non Linear Junctions)

Any type of metallic junction between multiple items of metal will cause a second harmonic to be generated. This signal may be created by solid state devices, diodes, transistors, or integrated circuits. However, this signal may also be caused by the presence of paper clips, rusty nails, sheetrock screws, steel studs, re-bar, upholstery springs, or any loosely touching metallic parts. This is considered a positive response, and will require further inspection involving a portable X-ray instrument, thermal imaging, borescopes, and other physical equipment. This may also be considered a non-linear assymetrical response. A noisy assymetrical response indicates the possibility of a corrosive target as opposed to a bugging device.

Power Level Issues

Non Linear Junction Detectors are available in a variety of power outputs ranging from the "civilian" version with an output below 25 mW, to the restricted Government version with a power output over 2 watts ERP. The Soviet and Chinese government actually use NLJD instruments which generate hundreds of watts of power, but often cost the TSCM specialist their vision (and other soft tissue damage) due to high levels of non-ionizing radiation. On an added note a NLJD should not be directed to any human or other living creature due to the potential of serious bodily harm. You can actually knock out a cardiac patients pacemaker from a distance with one, or cause serious soft tissue damage such as cornea injury, loss of hearing, kidney failure, and so on.

As the power output increases the greater the range of the unit, and the penetration into solid materials. However, as the power level increases, the sensitivity of the unit will decrease.

Normally a 2 Watt NLJD will detect an eavesdropping device through several inches of concrete, inside a wall, or buried deep inside a couch. The lower power units (50-100 mW) on the other hand will only detect eavesdropping devices inside a book, or devices only an inch or so away from the antenna (such as behind a few layers of sheetrock).

Non Linear Junction Detector transmit power is relatively meaningless. The sensitivity and bandwidth of the receiver is a far more important issue. Cheap units use high power to overcome poor receiver sensitivity and poor noise figures. In general the better units (more effective) are the lower powered ones.

Much like an X-ray the power level must be variable based on the density of the object being inspected. Of course the more power you generate the more "alerting" your activities become, and the higher the risk of personal injury (just like taking an X-Ray).

Generally a 1.5 Watt ERP unit with a variable output (adjustable down to around 5 mW ERP) works well, but if you use Digital Signal Processing or DSP in the unit to increase sensitivity the power levels can be drop to well below a Watt.

Frequency Issues

The 888 MHz products should be avoided as they tend to interfere with cellular telephone systems within the United States. On the other hand most professional eavesdroppers will monitor all popular NLJD channels to detect a TSCM sweep. For this reason it is advisable to utilize a non standard frequency, and to keep the power output as low as possible.

When a microwave sweep generator is synchronized and offset to a digital spectrum analyser the results are far superior to that of any NLJD (but much more expensive). For this reason NLJD's rapidly lost favor during the late 1980's, and have since been replaced with microwave sweep generators (if you don't mind dragging around an extra 60+ pounds of equipment). The technique of using a sweep generator as a NLJD signal is know a "Chirping".

A tunable NLJD works very well, but only after the spectrum has been checked with a spectrum analyzer. Also, the NLJD illumination signal may be pulsed to determine distance to the suspect junction and to reduce the power required (available in some NLJD systems). The pulse may also be created to appear like a legitimate communications signal (such as a POCSAG or CDPD data burst on an appropriate channel) to enhance operational security. Additionally, a pulsed signal may be coupled with a computer controlled receiver to radically increase the ability to detect potential threats.

NLJD Vulnerabilities and Weaknesses

Many modern eavesdropping devices utilize shielding and isolation circuits to hide the device from Non Linear Junction Detectors. Also, devices may contain special alarm circuits which will shutdown the device should a flooding frequency be detected or in some cases may even cause the device to self destruct with a small charge.

Perhaps the most valuable usage of a NLJD is the examination of organic, or quasi-organic objects such as potted plants, wooden desks, tables, books, and other things made of wood, fabric, composites, and non-metallic objects. The NLJD will also be valuable when examining wood paneling, wooden bookcases, paper, ceiling tiles, persian rugs, and so on. While a NLJD may be used with limited success on or near metallic surfaces such usage should be avoided as virtually every metallic junction will cause a false alert.

All weaknesses and misconceptions aside; the NLJD does have a place in every TSCM equipment inventory. When properly used during a sweep it will find eavesdropping devices that other instruments will miss. However; always remember that a NLJD is only one part of a complete set of TSCM equipment, and that it is only as good as the operator.

Popular Industry Models

| Spectrum Analyzers | Vector Signal Analysers | Demodulation | Time Domain Reflectometers |
| Antenna | Oscilloscopes | Multimeters | Craft Instruments | TSCM Specific Instruments |
| Non Linear Junction Detectors | Acoustic | Physical Search | Photographic and Imaging |
| Auxillary | Ancillary | Video | Vehicles |

Advanced TSCM Signals Detection and Analysis
TSCM - Sweeping the Spectrum for Eavesdropping Devices

Advanced TSCM Signals Detection and Analysis
TSCM - Sweeping the Spectrum for Eavesdropping Devices

Any comments or questions regarding this specific page?

Please feel free to sign our Guest Book

E-mail Address  
Web Page
Street Address
City (optional) State Zip
Country (optional)
Phone (optional)
How did you hear about this site or page?
Do you need to have a bug sweep or other TSCM service performed?
Do you need any TSCM equipment?

| Home | What is TSCM | Types of Bugs | Warning Signs You're Bugged |
| How To Behave if Bugged | TSCM Threat Levels | How To Engage a TSCM Firm |
| Qualifications | TSCM Protocol | Bug Frequencies | Phone Taps and Bugging |
| Signal Analysis | TDR Analysis | TDR Tutorial | Wiretapping | Training | Tools |
| Equipment | OSC-5000 | Kaiser | Riser Bond | Avcom | Search Rcvrs |
| Outside Links | Recommended TSCM Books | TSCM Reference Library |
| Recommended U.S. TSCM Firms | TSCM-L Mailing List |


    To be contacted for a confidential consultation
    please E-mail: jmatk@tscm.com

    or send a letter via US Mail to:
    James M. Atkinson
    Granite Island Group
    127 Eastern Avenue #291
    Gloucester, MA 01931-8008

    or call:
    Telephone: (978) 546-3803 / Fax: (978) 546-9467

    URL: http://www.tscm.com/

Copyright ©2002, Granite Island Group