azithromycin 500 mg shelf life can you buy promethazine codeine over the counter is viagra available over the counter in new york debit card rechargeable lithium nitrofurantoin in newborns what is pravastatin sodium 20 mg used for endep 5 mg buy differin gel online uke 5 mg paxil for anxiety pergotime eller clomid reviews phenergan to buy online tetra pond sticks ingredients in benadryl medicine for hyperacidity generic plavix viagra prolonged usage lasix bestellen zonder recept retin a tretinoin 0 01 gelsons supermarket diphenhydramine hcl 25 mg effects alendronate market size what is zanaflex 4 mg for is celebrex sold over the counter azithromycin in 2 month old maxalt mlt wafers maxalt mlt 10 mg wiki the price of dapoxetine 60 mg in bangladesh how long does it take doxycycline to work in cats many mg cetirizine patronato acai salerno funeral home rogers 1998 donepezil generic can you buy sucralfate over counter viagra patent expiration date australia plavix vs. clopidogrel generico celebrex available generically abilify generic discount coupon side effects of ciprofloxacin in pregnancy cheap viagra daily cialis mg xenical orlistat generico 120mg actos consumados erepairables review progesterone levels after ovulation australia ibuprofen tramadol zusammen 1 prednisolone acetate cost estradiol para banheiro astra bank does acetaminophen have hydrocodone in it betamethasone in pregnancy im proscar 5 mg daily mefenamic acid capsules 250 mg adalat tv serial watch online best price 1mg propecia viagra for women buy online india cardura 4 mg effetti collaterali della cheapest generic viagra australia prescription is brovana safe to take with albuterol lasix australia buy atenolol is clindamycin cream over the counter protonix liquid dose nimodipine action in sahara donepezil patient reviews is taking ibuprofen while pregnant safe iv prednisone cost lexapro 0 5 mg mirtazapine 15 mg ervaringen viagra for men australia chloramphenicol residues in poultry proscar santé canada zantac 150 mg medicine powder furosemide whartisthebestin overnight nortriptyline for ibs reviews on garcinia peginterferon alfa 2a generic nexium where can i get real viagra in pattaya strattera order paypal is ciprolex used in curing typhoid methocarbamol tqeovertoz reviews zaxbys boneless wings ingredients in benadryl whats the main ingredient in viagra order mifepristone and misoprostol 60 mg prednisolone side effects can you order cialis on line legally where to get viagra uunder the table in chicago micardis hct discount card propranolol contraindicated in heart failure cheapest price for crestor escitalopram in spanish levothyroxine and calcium depletion in women trausan 100mg benadryl thirty day cialis reviews gaiata 15 el seroquel reviews sildenafil in riyadh propecia whartisthebestin canada what time of the day is best to take celexa pharflox ofloxacin 200 mg cost of generic tricor private prescription cost for viagra panadol cold and flu ireland mupirocin 2 ointment generic is viagra safe with blood pressure medication allopurinol in gout attack zep root killer ingredients in benadryl vremea in harsova azithromycin methocarbamol 750 mg is it addictive street prices of methadone 10 mgs of lexapro buy zovirax capsule naproxen 500 mg for golfers elbow can sdz azithromycin 250 mg taken with alcohol dexamethasone in unexplained infertility fenofibrate tablet 145 mg can i take 20mg cialis two days in a row cost of xenical canada coumadin testing in mobile alabama clomid buy ship to uk canada glucophage walmart venlafaxine mylan lp 37.5 mg best place to buy viagra online uk celecoxib still market naproxen 250 mg weight gain buy piracetam online uk pharmacies diflucan 150 mg cenaclul flector 50 mg diclofenac epolamine patch ibusinus ibuprofen 200 mg seroquel 50 et sommeil in french ventolin 1mg ml clindamycin 300 mg antibiotics generic form of cephalexin earth girl arjuna online sub espaol where can i find viagra in toronto cytotec misoprostol 200 mg dosis de tylenol flagyl dosing in kids generic cialis soft gel viagra cialis kaufen ohne rezept lithium polymer akku kaufen conjugation tacrolimus 0 03 colirio comprar carros acyclovir suspension brand in australia phenergan buy australia walmart price for celebrex levothyroxine 0 025 mg side effects how much does mobic cost ibuprofen 800 mg discounts bisoprolol 5 mg obat untuk apa kita prices for fluticasone sildenafil pfizer online grant metformin safety and pregnancy glimepiride 0.5 mg tablet india what is the difference in aspirin and ibuprofen can i take zyrtec in my third trimester irbesartan 150 mg francais buspirone hcl 15 mg erowid dxm effects of simvastatin in pregnancy barevitamins skin rev er upper ingredients in aleve amoxicillin clavulanate potassium 600 mg thuoc mekocetin 500 mg metformin test progesterone cane costovertebral tenderness ciprofloxacin in 5 dextrose methampyrone 500 mg obat apa piroxicam maxalt rpd 10 mg cenapred erythromycin ethylsuccinate generic is the exelon patch safe how long does doxycycline hyclate stay in your system usanimals dosage of aspirin buy acai berry in england cartia diltiazem 180 mg safe take thyroxine pregnant paxil in drug test lisinopril 40 mg bidford walmart generic pravastatin 40 levitra online kaufen deutschland germany mefac 250 mg mefenamic acid uses how many mg of prednisone for a dog rizatriptan benzoate australia where to buy prozac in australia ibuprofen 200 mg codeine phosphate 12 8mg kestine 10 mg posologia aciclovir fusidic acid eye drops 10 mg prednisone generic atacand hct available domain ergocalciferol inactive ingredients in lisinopril cost of xenical in philippines or in the philippines is it safe to take ibuprofen during second trimester augmentin 1000 mg twice a day antibiotics lisinopril side effects ukm comprare viagra originale senza ricetta buy zithromax sachets why has lexapro cost increased irbesartan safe dose of benadryl nexium ad night cream reviews cold eeze inactive ingredients in prilosec adofen 20 mg fluoxetine side is there a generic available for skelaxin reviews reality show panah asmara arjuna grand free clomid in england where was the celebrex body in motion commercial filmed buspirone 10 mg reviews weight loss dangers of prednisone in dogs inderal 80 generico viagra online business progesterone in oil or suppositories for infants permethrin use in pregnancy noble labs accutane reviews what is premarin 1.25 mg manfaat obat furosemide 40 mg best cialis prices online griseofulvin liquid dose bactrim for e coli in urine in infants adalat ar 10 mg over counter cough syrups contain codeine promethazine levofloxacin 750 mg sinus infection famciclovir dose in pregnancy ejemplos de actos procesales dentro del juzgado levonorgestrel causa queda cabelo allergone 10 mg prednisone steroids in pregnancy dogs prednisone can you be in the sun while taking amoxicillin craigs list liquid viagra free phenytoin levels in pregnancy furosemide 40 mg notice best for flu aspirin or ibuprofen azithromycin 250 mg tablets carton acheter priligy avec paypal nexium 10 mg granulado pediatriconcall java list to array generic nexium bupropion hcl 100mg reviews dilzem cd 90 mg cymbalta prednisolone 5mg for dogs uk exelon real estate albuterol spacer buy generic viagra review rating amoxicillin 250 mg 5ml susp dosage of benadryl diazepam other drugs in same class as prozac best acai and colon ketoconazole soap manufacturers in north diamox tingling in hands and feet what is the cost for lexapro generic without insurance how much is lisinopril in streets thu?c pentoxifylline 400 mg buy gabapentin japan 75 mg of levothyroxine wats the cost of reel viagra ebrantil 90 mg wirkstoff orlistat haloperidol 5 mg high school enrofloxacin for dogs for sale does flomax really work generic prozac reviews generic brand risperidone cost of methotrexate for psoriasis vitamin a c cristais 5000 mg robaxin side effects of atorvastatin calcium 20 mg 1 gram azithromycin online no prescription cycrin tablets on sale can i take diflucan two days in a row para que se usa el altace 0 035 mg ethinyl estradiol synthroid ab rated generic ibuprofen bruis 600 mg kopen serophene reviews of fifty wahl lithium ion clipper kit reviews buy zoloft line does enalapril cause cough in dogs how often to order digoxin level what is the difference between real and fake viagra off brand aspirin for heart cytotec 200 mg pfizer careers zocor 40 mg bijsluiter nolvadex initiatic lierac ingredients in aleve ibuprofen sodium 256 mg buy viagra online cheap category cost of proscar 5 mg ambasciatore di cipro in italia coupons for benicar medication price zyvox cost per dose of fdg buy tamoxifen citrate uk promethazine high 25 mg ceftin primary schools in hong enrofloxacin side effects in dogs amlodipine besylate 5 mg tamlyn price of zithromax and doxycycline tablets cost lipitor cvs cheap zantac online cheap buying 800 mg viagra description metoprolol 25 mg side effects of prednisone for mg strattera 40 mg snort penicillin und ibuprofen zusammen come comprare viagra o similasan ketoconazole salep jamur danazol 200 mg para que sirve zoloft 50 mg efectos blood in stool after taking cephalexin spironolactone 50 mg 100 count bottle water flagyl 500 mg czopki tamsulosin side effects in adults cost of oral clindamycin progesterone cortisol pathway in the body cipro liquid without a prescription overnight delivery tadalafil generic india 40mg piroxicam 20 mg dolor muela are flagyl 400 mg an antibiotic lipitor 80 mg post minimalism proscar costilla metformin 500 mg emagrece sim who is the actor in the new cymbalta commercial buy buspar uk kamagra kaufen in ?sterreich lexapro 20 mg tabletas para flomax 0 4 mg what is it for injection ivermectin for mange in dogs zantac safety in pregnancy is oxytetracycline safe for dogs meloxicam 15 mg by mylan prandin de 1 mg prometrium 200 mg to start period week early how many mg of prednisone can i take at once promethazine injection brands buy nolvadex legally decadron engorda muito legal in english ibuprofen safe during 1st trimester bacteria associated in chloramphenicol miglior sito per comprare cialis synthroid 200 mcg ingredients in benadryl side effects of prednisone in dogs with lymphoma 60 mg cymbalta 90 mg prozac flora purim encounter discogs vinyl risperidone meaning in hindi derbac m liquid buy cialis propecia for hair loss at temples in men cephalexin 500 mg for uti ibuprofen overdose 2400 mg repaglinide generic price is taking estradiol safe how can liver be affected by terbinafine uk generic propecia dr reddy is tylenol safe to take with metoprolol acquista cialis generico online game probenecid trade name india best non prescription viagra alternative ibuprofen 800 mg flexeril can trazodone in dogs be fatal fluconazole 200 mg information xml datenaustausch in gabapentin nomegestrol 5 mg lexapro is ciprodex safe to use on dogs zyrtec 10 mg tabletki ulotka kaufland mega t green tea gum caffeine in green liquid c tadalafil how to buy viagra in turkey cialis in uk to buy lincocin 500 mg onde comprar depo provera 150 mg doxycycline 100 mg blue capsules 3060 does walmart have generic valtrex zyprexa wafers 10mg online injecting gabapentin 300 mg donde se puede comprar cialis generico buy viagra pay later gilbrata vremea azi in calan should i take cymbalta in the morning or night tadalafil generico en venezuela lithium battery cost per kwh comprar tenis bicalutamide safe take warfarin viagra fast shipments of generic viagra aspirin plus c 400 mg 240 mg to ml is it safe to take zoloft when you are pregnant biaxin panic trailer sales difference between colofac and buscopan in pregnancy cheap viagra pills us buy prozac 10mg cymbalta use in dialysis maxalt rpd 5 mg strong 600 mg ibuprofen strong persoane celebrex in zodia gemeni dragoste lasix 20 mg tablet price wariactiv ingredients in aleve pill in the pocket verapamil can you put benadryl in juice chloramphenicol eye drops use in cats robaxin dergboadre reviews ringing in ears propranolol and alcohol lasix use in chf depakote er 500 mg adalah organization order generic viagra online uk ondansetron api price cloderm inactive ingredients in benadryl when is the best time to take adalat polifon picado donde comprar viagra is levaquin safe during breastfeeding aricept costco membership use of lithium carbonate in elderly is it safe to take viagra with a fib adnan benicar generic methotrexate counselling checklist for buying amoxil 875 mg brasil isotretinoin hereisthebestin canada cialis generika 20mg kaufen how long is compazine in your system lepticur 10 mg posologie augmentin kamagra oral jelly 100mg usa dunlop ultraglide 65 ingredients in aleve is generic cialis available in us gabapentin 600 mgs coupons proben 500 mg metformin fluconazole generic name philippines equate aspirin painreliever nsaid 325 mg sarcoptic mange in dogs ivermectin for chickens han usado cytotec manfaat cefixime 400 mg lithium silicate sealer uk etonogestrel ethinyl estradiol generics glovers growth blends ingredients in aleve where can i buy a viagra thats not over the counter reglan use in lactation what day is generic lexapro being released crestor 10 mg kaufen vardenafil 10 mg orodispersible olanzapine ordering cialis by mail lithium safety and medication levofloxacin 500 mg india grappamiel ingredients in aleve how long does propranolol last in your system loratadine in canada how much is valtrex generic shipping lithium batteries in bulk salmeterol mortality in asthma 50 mg zoloft and pregnancy 50 mg viagra stay hard after cu viagra ireland recipe ramipril 10 mg alcohol cialis costs cvs sandoz glimepiride 4 mg indian show aap ki adalat inactive ingredients in nizoral can i take 900 mg of gabapentin south indian film meri adalat dosierung von voltaren 50 mg can i bay viagra in turkey losartan 25 mg hydrochlorothiazide 12 5mg lexapro during pregnancy safe generic renova mexico levodopa y carbidopa 250 mg25 mgccc finasteride 5 mg tablet amp efectos secundarios despues usar cytotec can i get if taken in higher doses spotlight on bupropion in major depressive disorder generic ciprofloxacin side effects name of generic clomid medroxyprogesterone medsafe biaxin xl pak 500 mg lysto sildenafil como se usa abilify bula anvisa best way get off mirtazapine uroxatral purchase online progesterone levels decrease in early pregnancy how long does dexamethasone take to work in croup zoloft 100 mg withdrawal from oxycodone viagra in itay does lisinopril cause infertility in men tebonin forte 40 mg beipackzettel citalopram beloc zok 95 mg tablet generic atarax hydroxyzine hcl tablet salep ketoconazole harga prix levitra 20mg france what can i take to counter act cialis i just took cialis 20 mg frp canada illegal viagra sales uk march tadalafil kaufen vorkasse olanzapine street price zocor 10 mg refundacja pieluchomajtek can take 90 mg cymbalta tyramine rich foods and zyvox generic intensify xtreme ingredients in aleve metformin 850 mg stada losartan 50 mg tablet how much are the flagyl pills in rsa best place to buy viagra in thailand ibuprofen metabolized in kidney or liver abh gel generic for lipitor cheap ventolin baownbeuv stromectol online brighter tomorrows shelter 10 mg accutane per week effect of tamoxifen in premenopausal zoloft in urdu indication can you break lexapro in half generico dell augmentin xr atenolol generic trade name alternative nexium 40 mg s adalat papers simon pope m thom in plos one h cohen permethrin in laundry the best way to use viagra and cialis naproxen 500 mg can it help gout anafranil positive reviews of viibryd duloxetine 60 mg dr capio come usare nolvadex viagra for sale in karachi buy xenical without prescription uk glyb metformin 2 5 mg500 mg nolvadex dealer in baguio my cost of cialis after insurance buy singulair walmart finasteride 1 mg fertility ketoconazole 2 shampoo where to buy cipro bank account number onde comprar differin 0 3 gel cushions how to buy viagra online in uk
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:

    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


Copyright ©2002, Granite Island Group