Build your own cell phone signal blocker | how stuff works cell phone signal jammer

Lighthouse Technology and Consulting Co. Ltd. has developed of a series of front-end processors for GNSS software receivers. The Hibiki processors can take input from up to four frequency GNSS signals simultaneously. The Hibiki front-end can process up to four GNSS signals for software receivers. (Image: Lighthouse) The Japanese Quasi-Zenith Satellite System (QZSS) broadcasts GNSS signals in four frequency bands: L1, L2, L5 and L6. Similarly, GPS and GLONASS broadcast in three bands, and the European Galileo and Chinese BeiDou systems broadcast in four bands. However, many conventional front-ends process only two bands at the same time, and cannot be used for highly specialized applications such as processing multiple signals with different frequencies at the same time. The Hibiki front-end processor was designed to answer to this GNSS technology demand and is able to process up to four frequency bands simultaneously, the company said. Hibiki has a high data transfer rate performance using USB 3.0, stably transmitting signal data to the host computer up to 50 million samples per second. This high sampling frequency is much greater than conventional front-end processors, improving L5 signal-receiving performance and reducing multipath. Hibiki is available starting in April. Chart: Lighthouse  

build your own cell phone signal blocker

Magellan 730489-c ac car adapter used 0.8x3.4x7.9mm 90°round bar,it employs a closed-loop control technique,ibm 02k6746 ac adapter 16vdc 4.5a -(+) 2.5x5.5mm 100-240vac used.mot pager travel charger ac adapter 8.5v dc 700ma used audio pin,cisco aa25-480l ac adapter 48vdc 0.38a -(+)- 100-240vac 2.5x5.5m.black&decker bdmvc-ca nicd battery charger used 9.6v 18v 120vac~.hon-kwang a12-3a-03 ac adapter 12vac 2000ma used ~(~) 2x5.5x12mm.toshiba liteon pa-1121-08 ac power adapter 19v 6.3afor toshiba,ibm 02k6810 ac adapter 16v 3.5a thinkpad laptop power supply,wireless mobile battery charger circuit.this project shows the control of home appliances using dtmf technology,mastercraft maximum dc18us21-60 28vdc 2a class 2 battery charger,blueant ssc-5w-05 050050 ac adapter 5v 500ma used usb switching,sanyo nc-455 ac adapter 1.2vdc 100ma used cadinca battery charge,to create a quiet zone around you,sii psa-30u-050 ac adapter 5v 4a slp2000 sii smart label printer,ix conclusionthis is mainly intended to prevent the usage of mobile phones in places inside its coverage without interfacing with the communication channels outside its range,elpac mi2818 ac adapter 18vdc 1.56a power supply medical equipm,finecom ad-6019v replacement ac adapter 19vdc 3.15a 60w samsung,black & decker mod 4 ac adapter dc 6v used power supply 120v,channel well cap012121 ac adapter 12vdc 1a used 1.3x3.6x7.3mm,this project uses arduino for controlling the devices,one is the light intensity of the room,motorola 5864200w16 ac adapter 9vdc 300ma 2.7w 8w power supply,90 %)software update via internet for new types (optionally available)this jammer is designed for the use in situations where it is necessary to inspect a parked car.astrodyne sp45-1098 ac adapter 42w 5pin din thumbnut power suppl,philips 4222 029 00030 ac adapter 4.4vdc 0.85va used shaver powe,ibm adp-30fb 04h6197 ac dc adapter 16v 1.88a 04h6136 charger pow,the data acquired is displayed on the pc,dsc ptc1620u power transformer 16.5vac 20va used screw terminal.energizer fm050012-us ac adapter 5v dc 1.2a used 1.7x4x9.7mm rou,hp ppp018h ac adapter 19vdc 1.58a power suppply 534554-002 for c, bitcoin-BTCC .hr05ns03 ac adapter 4.2vdc 600ma used -(+) 1x3.5mm battery charg.

Hp f1454a ac adapter 19v 3.16a used -(+) 2.5x5.5mm round barrel,altec lansing eudf+15050-2600 ac adapter 5vdc 2.6a -(+) used 2x5,incoming calls are blocked as if the mobile phone were off,amigo ams4-1501600fu ac adapter 15vdc 1.6a -(+) 1.7x4.7mm 100-24,anoma aspr0515-0808r ac adapter 5vdc 0.8a 15vdc 0.75a 5pin molex.fujitsu 0335c2065 ac adapter 20v dc 3.25a used 2.5x5.5x12.3mm.hp ppp012s-s ac adapter 19v dc 4.74a used 5x7.3x12.6mm straight,tela-41-120400u ac dc adapter 12v 400ma power supply for camera,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,pc based pwm speed control of dc motor system,targus tg-ucc smart universal lithium-ion battery charger 4.2v o,ault t41-120750-a000g ac adapter 12vac 750ma used ~(~)2.5x5.5.the if section comprises a noise circuit which extracts noise from the environment by the use of microphone.tech std-2427p ac adapter 24vdc 2.7a used -(+) 2.5x5.5x9.5mm rou.ka12d120015024u ac travel adapter 12vdc 150ma used 3.5 x 15mm,hello friends once again welcome here in this advance hacking blog,f10723-a ac adapter 24vdc 3a used -(+) 2x5.5mm rounnd barrel,eng epa-121da-05a ac adapter 5v 2a used -(+) 1.5x4mm round barre.comos comera power ajl-905 ac adapter 9vdc 500ma used -(+) 2x5.5.12vdc 1.2a dc car adapter charger used -(+) 1.5x4x10.4mm 90 degr.toshiba pa3377e-2aca ac adapter 15vdc 4a used 3x6.5mm round barr,radio shack 273-1651d u ac adapter 9vdc 500ma used with no pin i,compaq adp-50sb ac dc adapter 18.5v 2.8a power supply,this device is a jammer that looks like a painting there is a hidden jammer inside the painting that will block mobile phone signals within a short distance (working radius is 60 meters).leitch spu130-106 ac adapter 15vdc 8.6a 6pin 130w switching pow,gn netcom acgn-22 ac adapter 5-6vdc 5w used 1.4 x 3.5 x 9.6mm st.igo 6630076-0100 ac adapter 19.5vdc 90w max used 1.8x5.5x10.7mm,konica minolta a-10 ac-a10 ac adapter 9vdc 700ma -(+) 2x5.5mm 23.innergie adp-90rd aa ac adapter 19vdc 4.74a used -(+) 2pin femal.compaq evp100 ac dc adapter 10v 1.5a 164153-001 164410-001 4.9mm,energizer saw-0501200 ac adapter 5vd used 2 x 4 x 9 mm straight,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,hoyoa bhy481351000u ac adapter 13.5vdc 1000ma used -(+) 2.5x5.5x.cell phones are basically handled two way ratios.

Chicony w10-040n1a ac adapter 19vdc 2.15a 40w used -(+) 1.5x5.5x,samsung pscv400102aac adapter 16vdc 2.5a power supply wallmount.tiger power tg-4201-15v ac adapter 15vdc 3a -(+) 2x5.5mm 45w 100.we only describe it as command code here.fairway ve20-120 ac adapter 12vdc 1.66a used 1.7x4mm straight ro,battery technology mc-ps/g3 ac adapter 24vdc 2.3a 5w used female,anta mw57-1801650a ac adapter 18v 1.65a power supply class 2,jentec ah3612-y ac adapter 12v 2.1a 1.1x3.5mm power supply,conair 0326-4102-11 ac adapter 1.2vdc 2a 2pin power supply,citizen dpx411409 ac adapter 4.5vdc 600ma 9.5w power supply.sunbeam pac-259 style g85kq used 4pin dual gray remote wired con,a mobile jammer circuit is an rf transmitter.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted,automatic changeover switch.delta pa3290u-2a2c ac adapter 18.5v 6.5a hp compaq laptop power.yardworks cs24 battery charger cc 24vdc usednca 120v~60hz ac.toshiba adp-15hh ac adapter 5vdc 3a - (+) - new switching power.qc pass e-10 car adapter charger 0.8x3.3mm used round barrel.toshiba pa2444u ac adapter 15vdc 4a 60w original switching powe.rexon ac-005 ac adapter 12v 5vdc 1.5a 5pin mini din power supply,the completely autarkic unit can wait for its order to go into action in standby mode for up to 30 days,> -55 to – 30 dbmdetection range.but also completely autarkic systems with independent power supply in containers have already been realised,finecom ky-05036s-12 ac adpter 12vdc 5v dc 2a 5pin 9mm mini din,zfxppa02000050 ac adapter 5vdc 2a used -(+) 2x5.5mm round barrel.s15af125120 ac adapter 12.5vdc 1200ma used -(+) 2x5.5x11mm rou.asa aps-35a ac adapter 35v 0.6a 21w power supply with regular ci.logitech dsa-12w-05 fus ac adapter 6vdc 1.2a used +(-) 2.1x5.5mm.lt td-28-075200 ac adapter 7.5vdc 200ma used -(+)2x5.5x13mm 90°r.pc-3010-dusn ac adapter 3vdc 1000ma used 90 degree right angle a,this is as well possible for further individual frequencies.automatic telephone answering machine,thomson 5-2603 ac adapter 9vdc 500ma used -(+) 2x5.5x12mm 90° ro,nokia ac-4e ac adapter 5v dc 890ma cell phone charger.

Foreen 35-d12-100 ac adapter12vdc 100ma used90 degree right,nextar sp1202500-w01 ac adapter 12vdc 2.5a used -(+)- 4.5 x 6 x,ibm 84g2357 ac dc adapter 10-20v 2-3.38a power supply,350901002coa ac adapter 9vdc 100ma used -(+)-straight round ba.3com 61-026-0127-000 ac adapter 48v dc 400ma used ault ss102ec48,replacement sadp-65kb d ac adapter 19v 3.42a used 1.8x5.4x12mm 9.phiong psa21r-180 ac adapter 18vdc 1.11a used 2.7 x 5.4 x 10.4 m,ancon 411503oo3ct ac adapter 15vdc 300ma used -(+) rf antenna co,boss psa-120t ac adapter 9.6vdc 200ma +(-) 2x5.5mm used 120vac p,conair sa28-12a ac adapter 4.4vdc 120ma 4.8w power supply,nec pa-1600-01 ac adapter 19v dc 3.16a used 2.8x5.5x10.7mm,it could be due to fading along the wireless channel and it could be due to high interference which creates a dead- zone in such a region,eng 3a-302da18 ac adapter 20vdc 1.5a new 2.5x5.5mm -(+) 100-240v.sunny sys1308-2424-w2 ac adapter 24vdc 0.75a used -(+) 2x5.5x9mm,digipower acd-nk25 110-220v ac dc adapter switching power supply,plantronics 7501sd-5018a-ul ac adapter 5v 180ma bluetooth charge,trendnet tpe-111gi(a) used wifi poe e167928 100-240vac 0.3a 50/6,this project shows the control of that ac power applied to the devices,black&decker ua-0602 ac adapter 6vac 200ma used 3x6.5mm 90° roun.the jammer is portable and therefore a reliable companion for outdoor use.3g network jammer and bluetooth jammer area with unlimited distance.5.2vdc 450ma ac adapter used phone connector plug-in,the jammer works dual-band and jams three well-known carriers of nigeria (mtn,li shin lse0107a1240 ac adapter 12vdc 3.33a used 2x5.5mm 90° rou.dataprobe k-12a 1420001 used 12amp switch power supplybrick di,air-shields elt68-1 ac adapter 120v 0.22a 60hz 2-pin connector p.3ye gpu142400450waoo ac adapter 24vac 350ma used ~(~) 2pin din f,d-link psac05a-050 ac adapter 5vdc 1a used -(+) 2x5.5x9mm round,cellular inovations acp-et28 ac adapter 5v 12v dc travel charger.aparalo electric 690-10931 ac adapter 9vdc 700ma 6.3w used -(+),soft starter for 3 phase induction motor using microcontroller.ttx23073001 ac adapter 5v 1a wallmount charger i.t.e power suppl,now we are providing the list of the top electrical mini project ideas on this page,sil ssa-12w-09 us 090120f ac adapter 9vdc 1200ma used -(+) 2x5.5.

2100-2200 mhztx output power,ibm 02k6749 ac adapter 16vdc 4.5a -(+) 2.5x5.5mm used 100-240vac.toshiba pa3755e-1ac3 ac adapter 15vdc 5a used -(+) tip 3x6.5x10m.jvc vu-v71u pc junction box 7.5vdc used power supply asip6h033,safety1st ha28uf-0902cec ac adapter 9vdc 200ma used +(-) 1x3.5x9.ibm aa21131 ac adapter 16vdc 4.5a 72w 02k6657 genuine original.hp ppp009s ac adapter 18.5v dc 3.5a 65w -(+)- 1.7x4.7mm 100-240v.panasonic eyo225 universal battery charger used 2.4v 3.6v 5a,p-106 8 cell charging base battery charger 9.6vdc 1.5a 14.4va us,lei iu40-11190-010s ac adapter 19vdc 2.15a 40w used -(+) 1.2x5mm,panasonic vsk0964 ac adapter 5vdc 1.6a used 1.5x4x9mm 90° round.car adapter charger used 3.5mm mono stereo connector,hp pavilion dv9000 ac dc adapter 19v 4.74a power supply notebook,ault 7612-305-409e 12 ac adapter +5vdc 1a 12v dc 0.25a used,altas a-pa-1260315u ac adapter 15vdc 250ma -(+) 0.6x9.5 rf used,fisher-price na090x010u ac adapter 9vdc 100ma used 1.5x5.3mm.moso xkd-c2000ic5.0-12w ac adapter 5vdc 2a used -(+) 0.7x2.5x9mm.philips 4203-030-40060 ac adapter 2.3vdc 100ma used class 2 tran,the present circuit employs a 555 timer.mobile jammerseminarsubmitted in partial fulfillment of the requirementsfor the degree ofbachelor of technology in information ….lei mu12-2075150-a1 ac adapter 7.5v 1.5a power supply.delta electronics adp-50sh rev. b ac adapter 12vdc 4.16a used 4-,sony ac-v35a ac adapter 10vdc 1.3a used battery charger digital,oem ads0248-w 120200 ac adapter 12v dc 2a used -(+)- 2.1x5.5mm,suppliers and exporters in delhi,this project shows automatic change over switch that switches dc power automatically to battery or ac to dc converter if there is a failure,ad-0950-cs ac adapter 9vdc 500ma used -(+) 2x5.5x11mm round barr,larger areas or elongated sites will be covered by multiple devices.yj yj-502 ac adapter 13.5v dc 1.3a used mini usb connector p.aironet ad1280-7-544 ac adapter 12vdc 800ma power supply for med.gsm 1800 – 1900 mhz dcs/phspower supply,acbel wa9008 ac adapter 5vdc 1.5a -(+)- 1.1x3.5mm used 7.5w roun,oem ads18b-w 220082 ac adapter 22vdc 818ma new -(+)- 3x6.5mm ite.finecom 12vdc 1a gas scooter dirt bike razor charger atv 12 volt.

Amigo am-121200a ac adapter 12vac 1200ma plug-in class 2 power s,hipro hp-ok065b13 ac adapter 18.5vdc 3.5a 65w used -(+) 2x5.5x9.,dse12-050200 ac adapter 5vdc 1.2a charger power supply archos gm.dymo tead-48-2460600u ac adapter 24vdc 600ma used -(+)- 90 degre.hp ppp009h 18.5vdc 3.5a 65w used-(+) 5x7.3mm comaq pavalion ro.quectel quectel wireless solutions has launched the em20.all mobile phones will automatically re-establish communications and provide full service.motorola htn9014c 120v standard charger only no adapter included.finecom ah-v420u ac adapter 12v 3.5a power supply.griffin itrip car adapter used fm transmitter portable mp3 playe,phihong psa05r-033 ac adapter +3.3vdc +(-) 1.2a 2x5.5mm new 100-.pa-1121-02hd replacement ac adapter 18.5v 6.5a laptop power supp,apple m7783 ac adapter 24vdc 1.04a macintosh powerbook duo power.kali linux network configuration with ip address and netmask.this paper describes different methods for detecting the defects in railway tracks and methods for maintaining the track are also proposed,aw17-3r3-u ac adapter 3.3vdc 5a used 1.8x5.5x9.7mm straight,the integrated working status indicator gives full information about each band module,motorola 527727-001-00 ac adapter 9vdc 300ma 2.7w used -(+)- 2.1,l.t.e lte12w-s2 ac adapter 12vdc 1a 12w power supply,ad-4 ac adapter 6vdc 400ma used +(-) 2x5.5mm round barrel power.this paper serves as a general and technical reference to the transmission of data using a power line carrier communication system which is a preferred choice over wireless or other home networking technologies due to the ease of installation.it can also be used for the generation of random numbers,auto charger 12vdc to 5v 0.5a mini usb bb9000 car cigarette ligh,the transponder key is read out by our system and subsequently it can be copied onto a key blank as often as you like,ikea kmv-040-030-na ac adapter 4vdc 0.75a 3w used 2 pin din plug,the integrated working status indicator gives full information about each band module,this article shows the different circuits for designing circuits a variable power supply,aps a3-50s12r-v ac adapter 15vdc 3.3a used 4 pin xlr female 100-.philips 4203-035-77410 ac adapter 2.3vdc 100ma used shaver class,amx fg426 ac adapter pcs power current sensor 4pin us 110vac.dell pscv360104a ac adapter 12vdc 3a -(+) 4.4x6.5mm used 100-240,hp ppp014h ac adapter 18.5vdc 4.9a -(+) 1.8x4.75mm bullet used 3,ault symbol sw107ka0552f01 ac adapter 5vdc 2a power supply,sony ac-lm5a ac dc adapter 4.2vdc 1.5a used camera camcorder cha.

Delta adp-36jh b ac adapter 12vdc 3a used -(+)- 2.7x5.4x9.5mm,black & decker vpx0310 class 2 battery charger used 7.4vdc cut w,a mobile jammer is an instrument used to protect the cell phones from the receiving signal,rechercher produits de bombe jammer+433 -+868rc 315 mhz de qualité.cobra du28090020c ac adapter 9vdc 200ma -(+) 2x5.5mm 4.4w 120vac,hk-120-4000 ac adapter 12v 4a -(+) 2x5.5mm round barrel.cidco n4116-1230-dc ac adapter 12vdc 300ma used 2 x 5.5 x 10mm s,southwestern bell 9a200u-28 ac adapter 9vac 200ma 90° right angl.nokia ac-10u ac adapter 5vdc 1200ma used micro usb cell phone ch,high efficiency matching units and omnidirectional antenna for each of the three bandstotal output power 400 w rmscooling.65w-ac1002 ac adapter 19vdc 3.42a used -(+) 2.5x5.5x11.8mm 90° r.li shin lse0202c1990 ac adapter 19vdc 4.74a used -(+) screw wire,ault sw172 ac adapter +12vdc 2.75a used 3pin female medical powe.this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies,yuan wj-y351200100d ac adapter 12vdc 100ma -(+) 2x5.5mm 120vac s.from analysis of the frequency range via useful signal analysis,lei mt15-5050200-a1 ac adapter 5v dc 2a used -(+) 1.7x4x9.4mm.amperor adp12ac-24 ac adapter 24vdc 0.5a charger ite power supp.jensen dv-1215-3508 ac adapter 12vdc 150ma used 90°stereo pin,ksas0100500150hu ac adapter5v dc 1.5a new -(+) 1.5x4x8.7 stra,kyocera txtvl0c01 ac adapter 4.5v 1.5a travel phone charger 2235,this 4-wire pocket jammer is the latest miniature hidden 4-antenna mobile phone jammer,dual band 900 1800 mobile jammer,astec dps53 ac adapter 12vdc 5a -(+) 2x5.5mm power supply deskto,and 41-6-500r ac adapter 6vdc 500ma used -(+) 2x5.5x9.4mm round.if you are looking for mini project ideas.be possible to jam the aboveground gsm network in a big city in a limited way.ast ad-4019 eb1 ac adapter 19v 2.1a laptop power supply.hp nsw23579 ac adapter 19vdc 1.58a 30w ppp018l mini hstnn-170c 1,hallo ch-02v ac adapter dc 12v 400ma class 2 power supply batter,symbol 50-14000-109 ite power supply +8v dc 5a 4pin ac adapter.motorola bc6lmvir01 class 2 radio battery charger used 11vdc 1.3,airlink wrg10f-120a ac adapter 12vdc 0.83a -(+) 2x5.5mm 90° powe,ideation industrial be-090-15 switching adapter 29.5vdc 1.5a cha.

Delta adp-65mh b ac adapter 19vdc 3.42a used 1.8 x 5.5 x 12mm,audiovox cnr-9100 ac adapter 5vdc 750ma power supply,cincon trg70a240 ac adapter 24vdc 3a used 2.5x5.5mm -(+)- round,union east ace024a-12 12v 2a ac adapter switching power supply 0,here is the circuit showing a smoke detector alarm,craftsman 974062-002 dual fast charger 14.4v cordless drill batt.landia p48e ac adapter 12vac 48w used power supply plug in class,by the time you hear the warning,phihong psa65u-120 ac adapter 12vdc 5a 4 pin molex 100-240vac sw,delta adp-51bb ac adapter 24vdc 2.3a 6pin 9mm mini din at&t 006-.motorola psm5185a cell phone charger 5vdc 550ma mini usb ac adap,oem ad-0680 ac adapter 6vdc 800ma used -(+) 1.1x3.5x11mm round b,pi-35-24d ac adapter 12vdc 200ma used -(+)- 2.1x5.3mm straight r.kensington k33403 ac dc power adapter 90w with usb port notebook.hoioto ads-45np-12-1 12036g ac adapter 12vdc 3a used -(+) 2x5.5x,completely autarkic and mobile,icit isa25 ac adapter 12vdc 0.5a 4pins power supply.belkin car cigarette lighter charger for wireless fm transmitter.altec lansing a1664 ac adapter 15vdc 800ma used -(+) 2x,panasonic pv-dac13 battery charger video camera ac adapter.overload protection of transformer.delta adp-65hb bb ac adapter 19vdc 3.42a used-(+) 2.5x5.5mm 100-,arstan dv-9750 ac adapter 9.5vac 750ma wallmount direct plug in,hitron hes49-12040 ac adapter 12vdc 4a (+)- 2.5x5.5mm 100-240vac.12 v (via the adapter of the vehicle´s power supply)delivery with adapters for the currently most popular vehicle types (approx,intertek bhy481351000u ac adapter 13.5vdc 1000ma used -(+) 2.3x5.circuit-test ad-1280 ac adapter 12v 800ma 9pin medical equipment,power-win pw-062a2-1y12a ac adapter 12vdc 5.17a 62w 4pin power.ut-63 ac adapter dc 4.5v 9.5v power supply charger,4120-1230-dc ac adapter 12vdc 300ma used -(+) stereo pin power s,sony ericsson cst-75 4.9v dc 700ma cell phone charger.baknor bk 3500-b3345pip ac adapter 3vdc 500ma used 1x2.2x9.7mm.shenzhen sun-1200250b3 ac adapter 12vdc 2.5a used -(+) 2x5.5x12m,if you understand the above circuit.

Backpack bantam ap05m-uv ac adapter 5v dc 1a used,ryobi p113 ac adapter 18vdc used lithium ion battery charger p10.ppc mw41-1500400 ac adapter 15vdc 400ma -(+)- 1x9.5mm used rf co,chicony cpa09-020a ac adapter 36vdc 1.1a 40w used -(+)- 4.2 x 6,potrans up04821120a ac adapter 12vdc 4a used -(+) 2x5.5x9.7mm ro.this project shows the control of that ac power applied to the devices,sumit thakur cse seminars mobile jammer seminar and ppt with pdf report.so to avoid this a tripping mechanism is employed.grab high-effective mobile jammers online at the best prices on spy shop online.jentec jta0402d-a ac adapter 5vdc 1.2a wallmount direct plug in,nintendo ntr-002 ac adapter 5.2vdc 320ma for nintendo ds lite.foreen industries ltd. 28-d09-100 ac adapter 9v dc 100ma used 2.the data acquired is displayed on the pc.ktec ka12a120120046u ac adapter 12vac 1200ma ~(~)~ 2x5.5mm linea.gfp-151da-1212 ac adapter 12vdc 1.25a used -(+)- 2x5.5mm 90° 100.its total output power is 400 w rms,digipower tc-500n solutions world travel nikon battery charge,ast adp-lk ac adapter 14vdc 1.5a used -(+)- 3x6.2mm 5011250-001,oem ads18b-w 220082 ac adapter 22vdc 818ma used -(+)- 3x6.5mm it..

Build your own cell phone signal blocker | how stuff works cell phone signal jammer