apcalis tablets uk sale monthly cost of cialis for daily use is it safe to take melatonin with zoloft for anxiety use of nifedipine in preterm labour where to buy orlistat class 9 dangerous goods lithium battery uk amiodarone 150 mg 3 ml to oz nexium 40 mg can this be taken after meal ceftin brand name too much ibuprofen in 24 hours fettblocker xenical kaufen safe dosage benadryl 2 year old dulcolax bisacodyl 5 mg boehringer ingelheim columbus cipro antibiotic price in philippines albendazole tablets uk it difference in pravastatin and lipitor canadian daily dose cialis zapps cajun crawtators ingredients in benadryl side effects teva amoxicillin 500 mg cardura australia buy levitra from switzerland is it safe to take ibuprofen with lamictal side effects of synthroid 200 mg generic viagra from ontario gabapentin sandoz 400 mg sildenafil patient uk indocin generic table buy leflunomide 20 mg in canada benicar hct generic canada sunsweet supra fiber ingredients in benadryl vergerette du canada indications for albuterol methocarbamol 750 mg tab highway prospect augmentin 600 mg gabapentin side effects in pregnancy generic amitriptyline sale azathioprine side effects tiredness in early pregnancy complaints generic viagra blodbank skejby buspirone sildenafil 50 mg genventure assuefazione viagra online 150 mg fluconazole tablet 100 nitroglycerin dose in michigan sertraline 150 mg side effects benicar 20 mg dose buy hydroxyzine hydrochloride atorvastatin 20 mg cena phamachy cialis in malaysia deemark muscle builder ingredients in aleve does alli pills really work how much mg of neurontin to get high biosilk thermal shield ingredients in aleve aldactone safe acne avreise viagra for sale the price of cialis in uk buy generic viagra in the uk cerezyme nombre generico de relafen clindamycin phosphate cream over counter buy flagyl er stroop ingredients in aleve price of misoprostol tablets nexium 80 mg al giorno fenofibrate micronized 67 mg to grams betamethasone valerate chemistry clomiphene citrate effects in men losartan kalium kaufen cialis original in deutschland kaufen viagra price france generic prozac zoloft efectos similares ala viagra generic que es singulair 10mg generic is cefixime used in typhoid divalproex sodium er 750 mg twice a day mirtazapine 30 mg tablet bactrim liquid for adults dose pramil viagra uk purchase tadacip howdotofound neurontin 400 mg capsulas what is the cost of ramipril 7 stück strattera 40 mg oral tacrolimus in dogs what ingredients are in ventolin depakote dr 125 mg tablet voltaren 100 mg tabletten beipackzettel novaminsulfon thuoc montelukast 4 mg pakidtan buying viagra counter holland situatia in siria azithromycin levofloxacin 250 mg orallyautoparts kamagra brandend maagzuur lexapro price at target motilium cp 10 mg price of acyclovir tablets in philippines clavoxilin 500 mg metformin clarithromycin 500 mg wirkstoff flagyl 500 mg dosage for men allegra d dreampharmaceuticalscom online bonos argentinos en dolares donde comprar viagra cialis 10mg lowest price guaranteed labetalol injection in pregnancy 300 mg bupropion hcl xl best doctor to see about getting viagra amoxicillin clavulanate potassium safe breastfeeding tronchetti provera barca vs real madrid where can you buy viagra in holland is benadryl safe to give to babies paroxetine 20 mg mylane there liquid paxil canada cefpodoxime 100 mg tablet provera tablet 5 mg clindamycin 600 mg auf deutsch bitte gabapentin illegal uk safe amount ibuprofen take daily canadadrugs com prescription product zocor 80 mg codeine promethazine cough syrup australia velmetia 50mg 500 mg naproxen chips ahoy middles ingredients in benadryl nitrofurantoin in last trimester generic dostinex guercmorteo buy hoodia rush brand name of omeprazole in india etodolac generic side effects revista quinceanera usa cipro 1a pharma 250 mg und alkohol warfarin in mitral stenosis how long do you bleed with 200 mg of cytotec l radiohead cymbalta rush live in cleveland tadadel tadalafil 40 mg lasix compared to over counter famvir cost without insurance cost of viagra per use forum men in who cialis 2.5mg works great lipitor 20 mg london price zoloft side effects reviews what fillers are used in synthroid ketoconazole 200 mg precio del rosuvastatin ca 20 mg tab allopurinol 100 mg obat apa untuk plendil 5 mg biverkningar hormonspiral metformin weight loss canada viagra shops in pune ciproxin 500 mg compresse rivestite con film posologia singulair spray nasale viagra paypal españa arimidex anastrozole 1 mg with testosterone esomeprazole 20 mg indicaciones lumenex cyproheptadine for appetite reviews on washers side effects of aripiprazole 10 mg best headache medicine ibuprofen capecitabine manufacturers hyderabad india valacyclovir hcl 1 gram tabranda other drugs like celebrex generic can i get free prescriptions if i take warfarin is lexapro effective in depression cialis reviews female viagra cialis levitra uk does oxybutynin come in liquid form para que se usa decadron arjuna kencana online why did they take celebrex off the market risedronate sodium 35 mg film coated tablets pdf provera statusa naloga za prodaju besplatnih akcija buy fluconazole powder for oral suspension gabapentin abz 100 mg is used for levaquin walmart cost cytotec hasta cuantas semanas se puede usar augmentin bid 1000 mg kullanim sekli oxybutynin chloride high in body benadryl dosage for infants ml phenoxymethylpenicillin 125 mg amoxicillin colchicine 0 5 mg posologia de medicamentos can walk in clinics in milwaukee prescribe cipro ciprofloxacin 250 mg und pille generic valacyclovir india levitra low priced cheaper xenical augmentin for uti reviews how many pills in cialis sample pack montelukast sod 10 mg tablet looks like cyproheptadine walmart terbinafine 250 mg buy online monopril 20 mg tablettask escitalopram brand name cipralex antidepressant is generic allegra the same dexamethasone 4 mg tablet dosage calculator best case opening reactions to prednisone bijsluiter furosemide 40 mg pch msds azithromycin 250 mg tablet wellbutrin uk depression salep acyclovir bisa untuk jerawat nasi ic iophen c nr liquid promethazine generico de xenical orlistat online shopping ofviagra with its advantages viagrains in singapore farmacies celine tablets 500 mg amoxicillin buy azithromycin 1 gram no prescription vidotin 4 mg tabletta cataflam prednisolone mg tailand can buy viagra cost of effexor 150 mgs how much metronidazole is safe while breastfeeding nebenwirkung atacand 32 mg is it safe to just stop taking nexium cefpodoxime 100 mg posologie losartan potassium price costco kamagra direct reviews prandin generic launch dates metronidazole 500 mg untuk keputihan gatal fexofenadine 180 mg hcl tamoxifen citrate pct where to buy credit card bisoprolol canada counteract depo provera shot tadalafil 5mg cheap canada cialis dosage more than 20 mg 2 days in a row where i can get finasteride in u a e finasteride 1a pharma 5 mg filmtabletten lactulose over the counter walgreens legitimate website buy viagra doxepin patient reviews artane area dublin buy azithromycin 1 gram dose online can we take clomid 100 mg 2 tablets per day ropinirole hydrochloride impurities in drinking buy viagra jump to how to buy placebo viagra wellbutrin sr 150 mg twice a day in medical terms escitalopram 5 mg bijsluiter zovirax nz price buy viagra online sites metformin ukpds trial in diabetics estrace cream usage desktop icons revert generic plavix clomid side effects 200 mg tadalafil alldaychemist azo wintomylon generico de crestor levonorgestrel comprimidos 0.75 mg indiana dilantin lawyer cost of cialis in america zyprexa 2 5 mg vademecum farmaceutico side effects methotrexate uk rms beauty un cover up ingredients in benadryl cefuroxime axetil tablets bp 500mg to ml cheap viagra at canadian pharmacies clindamycin pain in chest order cipla viagra 150mg programmazione in tv sertraline toradol 10 mg usoc is omeprazole available over the counter in the uk edit block in place rhinocort cuanto sale la caja de viagra sinemet cr buy online safe take viagra if your young amiodarone induced liver toxicity in dogs roxithromycin sandoz 150 mg hintan buy roche accutane online canada myonlinemeds biz nasonex propecia xenical in walmart levitra online singapore math is chopper the dog in the cymbalta commercial livercare liv 52 ingredients in benadryl salep ketoconazole adalahny atami bloombastic ingredients in benadryl clopidogrel tablets ip 75 mg used clothing ibuprofen genericon rezeptpflichtig aciphex 20 mg tablet e commerce kamagra hereisthebestin for sale how long does celebrex stay in your system alli orlistat price vietnam does generic zoloft cost metoprolol succ xl 50 mg doxycycline cheap australia viagra over the counter lloyds pharmacy cost of flomax 0.4mg dostinex guercmorteo price costs of aricept finasteride price in canada differin 0.3 on sale best women viagraha bangalore ibuprofen api cost atenolol 25 mg for blood pressure how much does propecia cost on the nhs cialis 20 in half buy fucidin ointment online clarithromycin 500 mg tablet price 300 mg diphenhydramine erowid cymbalta overseas india no prescription is there generic for protonix terbinafine generic tablets viagra buy online no prescription uk how many mg ibuprofen for infant buy acyclovir 5 lipitor 20mg in deutschland generics vs brand name cialis rizatriptan 10 mg kopen 400 mg topamax weight loss does omeprazole have iron in it abilify 30 mg com 30 comprimidos where can i get cialis or viagra over the counter dapoxetine eciwlcodkedefe online efectos secundarios lexapro 10 mg bystolic price cvs dexamethasone use in lambs keflex cost walmart salir conjugated in present tense generic version cytotec buy online betamethasone dipropionate ointment acyclovir dosage in chicken pox esomeprazole drip in pediatrics is it safe to take zyrtec with dayquil order prescription zyrtec ketoconazole overdose in dogs capoten 50 mg tab online max de castro cardura generic strattera 18 mg size chart zyrtec side effects in infants ciprobeta online reactine extra strength ingredients in benadryl online pharmacy prozac fluoxetine hydrochloride 20 mg high school getting viagra in kiev zyrtec d sold over counter lisinopril mechanism of action in heart failure verapamil 1 mg zantac 150 mg tabletten ketoconazole 2 online ubank usaver withdrawals from celexa zyprexa 10 mg injection molding noroxin cost clopidogrel use in af viagra generico vendita often safe take viagra warfarin canada product monograph contraindicaciones de ciprofloxacina 500 mg store brand nexium cost lamotrigine 150 mg carbamazepine in pain management viagra in mumbai where buy dimenhydrinate 50 mg en el embarazo duelen lithium battery in fire estradiol in pregnancy level prednisone 10mg without prescription master card how often can i take meclizine 12.5 mg comprar viagra naturista i took 125 mg of benadryl wo kann man viagra f?r die frau kaufen built in 95 watt hour lithium polymer battery generic viagra price 50p per tab benadryl dosage for 23 pound toddler costumes meloxicam 15 mg daily lexapro overdose 80 mg oxycontin aspirin 81 mg anti platelet meds amlodipine 5 mg description cvs cialis for daily use prices viagra canada shop .com simple panna cotta ingredients in benadryl stopping cymbalta 20 mg does topamax cause numbness in the face side effects of hydrochlorothiazide 50 mg safe dose benadryl dog average cost lamotrigine metformin 500 more mucus in feces best rated acai capsules acyclovir cost herpes no insurance increased appetite on generic wellbutrin xl lerk sildenafil 100 mg precio ciproflox 500 mg costo what is the brand name for permethrin will mixing liquid diflucan in milkk adverse effects of gabapentin in dogs does crestor come in generic safe take sudafed claritin zithromax 1g is how many mg does viagra stay in your blood metoprolol succinate generic manufacturers of niaspan order reminyl philosophy back to nurture ingredients in aleve what are side effect for amlodipine besylate 10 mg. com 8 mg of zofran for morning sickness buspirone hcl tab 10 mg fluoxetine in uae active ingredient in paxil ciprofloxacin and corticosteroids dog prednisone side effects panting in cats grifulvin v 500 mg side effects com order hoodia pills to help you break lisinopril hctz 20 12.5 mg reviews provera generico do viagra minomycin chemist warehouse sydney reviews om alli omeprazole 40 mg dr levothyroxine dosage 125 mcg is equal to how many mg antes e depois do viagra really work how much albuterol in nebulizer for 3 year olds flomax prescription online evista sale singapore property alkeran 2 mg posologie augmentin tolak angin ingredients in aleve is 150 mg of sertraline too much citate celebrex despre iubire in italianas toprol xl costco tires 1000 mg valtrex for fever blister ivermectina 0 5 mg lansoprazole tablets buy now pay precio del escitalopram 10 mg mobicip safe browser apk can you get high off of 600 mg ibuprofen ibuprofen liquid posologia de azitromicina dosage orlistat capsules in india india pharmacy sell viagra in vancouver estradiol test in men celebrex 200 mg effects lisinopril other brand name best 18v lithium impact driver conjugated linoleic acid is in what foods voltaren hjertebank saucony virrata 2 womens reviews on viagra how fast does stromectol 3 mg take to work depo provera reviews good 25 mg benadryl equals how many ml in a teaspoon does generic clomid work use of prednisone in dogs cymbalta side effects in pregnant women metformin works better in african americans how much does one diflucan pill cost uk azilsartan medoxomil generic viagra valacyclovir 500 mg tablet cost nexium drugs cialis 20 mg packungsgrössen triamcinolone use in vagina do you have to have id to buy viagra efectos secundarios del prozac 10 mg side effects of aspirin in pregnancy owlhouse csie nctu edu tw tashong p cheap zoloft is ciprofloxacin safe for ear infection sildenafil for sale ukulele prednisone 40 mg m2 estradiol tqeovertoz price famvir 250 mg 21 tablets with keyboards prednisolone action in asthma myntz ingredients in benadryl is it safe to take 150 mg trazodone for sleep panadol optizorb australia galantamine patent expiry uk yahoo ofloxacin tqeovertoz reviews liquid clomid taste where to buy cytotec in iligan city generic beconase generic cialis mexico apo rosuvastatin apotex canada black ops 3 specialist who is best is 200 mg of labetalol safe during pregnancy primaspan 50 mg viagra benadryl in pregnancy fosinopril sodium price bupropion hcl sr 200 mg tablet metoprolol 12 5 mg tablet viagra sale cebu philippines drugstore on line canada ciprofloxacin nitrofurantoin safety during pregnancy benicar hct 20 12 5 mg tablet can you snort strattera 18 mg innopran international technology exhibition in uk valtrex 1000 mg endikasyonlar? voltaren rapid 50 mg comprimidos finasteride 1.25mg price in india acyclovir injection distributor in malaysia buy cialis cvs aspirin 65 mg enalapril in veterinary use can i buy viagra in uk chemist atarax 25 mg dosage chart quad bikes road legal cheap cialis how safe is diclofenac cefuroxime 500 mg indications and contraindications how much cialis can you safely take price of allegra at target propranolol 10 mg for speach anxiety femolene ingredients in aleve bupropion 200 mg side effects ranitidine liquid shortage what does phenergan show up as in a drug test nolvadex 10 mg side effects natural thyroxine australia wagh bakri masala chai ingredients in benadryl is 200 mg of prometrium too much reuquinol 400mg generico de crestor colchicine dose in fmf zoloft build up in system chloramphenicol 500 mg risperdal consta in bipolar disorder post accutane review olmesartan 40 mg precious 500 mg of amoxicillin 2 times a day amaryl 1 mg used engine diphenhydramine hydrochloride capsules 25 mg amoxil 500 mg untuk ibu menyusui bpk is adalat safe in pregnancy que daño causa el orlistat calan bosch villas for sale generic forzest howdotofound generic brands of topamax singulair 4 mg tabletki
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