Off-the-Shelf Antennas for Controlled-Reception-Pattern Antenna Arrays
By Yu-Hsuan Chen, Sherman Lo, Dennis M. Akos, David S. De Lorenzo, and Per Enge
INNOVATION INSIGHTS by Richard Langley
THE ANTENNA IS A CRITICAL COMPONENT OF ANY GNSS RECEIVING EQUIPMENT. It must be carefully designed for the frequencies and structures of the signals to be acquired and tracked. Important antenna properties include polarization, frequency coverage, phase-center stability, multipath suppression, the antenna’s impact on receiver sensitivity, reception or gain pattern, and interference handling. While all of these affect an antenna’s performance, let’s just look at the last two here.
The gain pattern of an antenna is the spatial variation of the gain, or ratio of the power delivered by the antenna for a signal arriving from a particular direction compared to that delivered by a hypothetical isotropic reference antenna. Typically, for GNSS antennas, the reference antenna is also circularly polarized and the gain is then expressed in dBic units.
An antenna may have a gain pattern with a narrow central lobe or beam if it is used for communications between two fixed locations or if the antenna can be physically steered to point in the direction of a particular transmitter. GNSS signals, however, arrive from many directions simultaneously, and so most GNSS receiving antennas tend to be omni-directional in azimuth with a gain roll-off from the antenna boresight to the horizon.
While such an antenna is satisfactory for many applications, it is susceptible to accidental or deliberate interference from signals arriving from directions other than those of GNSS signals. Interference effects could be minimized if the gain pattern could be adjusted to null-out the interfering signals or to peak the gain in the directions of all legitimate signals. Such a controlled-reception-pattern antenna (CRPA) can be constructed using an array of antenna elements, each one being a patch antenna, say, with the signals from the elements combined before feeding them to the receiver. The gain pattern of the array can then be manipulated by electronically adjusting the phase relationship between the elements before the signals are combined. However, an alternative approach is to feed the signals from each element to separate banks of tracking channels in the receiver and form a beam-steering vector based on the double-difference carrier-phase measurements from pairs of elements that is subsequently used to weight the signals from the elements before they are processed to obtain a position solution. In this month’s column, we learn how commercial off-the-shelf antennas and a software-defined receiver can be used to design and test such CRPA arrays.
“Innovation” features discussions about advances in GPS technology, its applications, and the fundamentals of GPS positioning. The column is coordinated by Richard Langley, Department of Geodesy and Geomatics Engineering, University of New Brunswick. To contact him with topic ideas, email him at lang @ unb.ca.
Signals from global navigation satellite systems are relatively weak and thus vulnerable to deliberate or unintentional interference. An electronically steered antenna array system provides an effective approach to mitigate interference by controlling the reception pattern and steering the system’s beams or nulls. As a result, so-called controlled-reception-pattern-antenna (CRPA) arrays have been deployed by organizations such as the U.S. Department of Defense, which seeks high levels of interference rejection.
Our efforts have focused on developing a commercially viable CRPA system using commercial off-the-shelf (COTS) components to support the needs of Federal Aviation Administration (FAA) alternative position navigation and timing (APNT) efforts. In 2010, we implemented a seven-element, two-bit-resolution, single-beam and real-time CRPA software receiver. In 2011, the receiver was upgraded to support all-in-view, 16-bit-resolution with four elements.
Even though we can implement these CRPA software receivers in real time, the performance of anti-interference is highly dependent on the antenna array layout and characteristics of the antenna elements. Our beamforming approach allows us to use several COTS antennas as an array rather than a custom-designed and fully calibrated antenna. The use of COTS antennas is important, as the goal of our effort is to develop a CRPA for commercial endeavors — specifically for robust timing for the national airspace. Hence, it is important to study the geometry layout of the individual antennas of the array to assess the layouts and to determine how antenna performance affects the array’s use.
In our work, we have developed a procedure for calculating the electrical layouts of an antenna array by differential carrier-phase positioning. When compared to the physical layout, the results of electrical layouts can be used to determine the mutual coupling effect of each combination. Using the electrical layout, the resultant gain patterns can be calculated and used to see the beamwidth and the side-lobe issue. This is important as these factors have significant effects on anti-interference performance. This study focuses on understanding the performance effects of geometry and developing a method for describing the best geometry.
We adopted three models of COTS antenna and two possible layouts for a four-element array. Then, signal collection hardware consisting of four Universal Software Radio Peripheral (USRP) software-defined radios and one host personal computer was assembled to collect array data sets for each layout/antenna combination. Our developed CRPA software receiver was used to process all data sets and output carrier-phase measurements.
In this article, we will present the pattern analysis for the two selected layouts and describe how we collected the experimental data. We’ll then show the results of calculating the electrical spacing for the layouts are compare them to the physical layouts. Lastly, we’ll show the resulting patterns, discuss the antenna mutual coupling effects, and give our conclusions.
Antenna Array Pattern Analysis
Pattern is defined as the directional strength of a radio-frequency signal viewed from the antenna. The pattern of an antenna array is the product of the isotropic array factor and the isolated element pattern. We assume that the pattern of each element is identical and only consider the isotropic array factor. FIGURE 1 shows the coordination of an antenna array. The first element is set as a reference position. The x-axis is the east direction, the y-axis is the north direction, and the z-axis is the up direction. The baseline vector of the ith antenna is given by and is the unit vector to the satellite.
Figure 1. Antenna array geometry and direction of satellite. Array elements are identified as E#1, E#2, E#3, and E#4.
The isotropic array factor is given by
(1)
where λ is wavelength, and Ai is a complex constant. Currently, we only implement a four-element-array CRPA software receiver in real time. Hence, we analyze two kinds of layout of half-wavelength four-element arrays: a symmetrical Y array and a square array. Each antenna is separated from its nearest neighbor by a half wavelength. FIGURE 2 shows photos of the two layouts. FIGURE 3 shows the physical layouts.
Figure 2. Photos of antenna arrays (left: Y array; right: square array).
Figure 3A. Physical layout of antenna arrays (Y array).
Figure 3B. Physical layout of antenna arrays (square array).
The antenna patterns towards an elevation angle of 90 degrees, computed using equation 1 and the design layouts, are shown in FIGURE 4. One of the key characteristics of a pattern is the beamwidth, which is defined as the angle with 3-dB loss. FIGURE 5 shows the patterns in elevation angle where the beamwidth of the Y layout is 74 degrees and 86 degrees for the square layout. A narrow beamwidth will benefit anti-interference performance particularly if the interference is close to the direction of a target satellite.
Figure 4. Patterns of antenna arrays (left: Y array; right: square array).
Figure 5. Pattern beamwidths of Y and square arrays (3 dB beamwidth shown).
Specifications of COTS Antennas
Typically, the COTS antenna selection is determined by high gain and great out-of-band rejection. TABLE 1 shows the specifications of the three antenna models used in this article. These antennas are all patch antennas. The antennas are equipped with surface-acoustic-wave filters for rejecting out-of-band signals. A three-stage low noise amplifier with over 30 dB gain is also embedded in each antenna.
Table 1. Specifications of COTS antennas used.
Signal Collection Hardware and Experimental Setup
The hardware used to collect the antenna array datasets is shown in FIGURE 6 with block-diagram representation in FIGURE 7. The hardware includes a four-element antenna array, four USRP2 software radio systems and one host computer. The signal received from the COTS antenna passes to a USRP2 board equipped with a 800–2300 MHz DBSRX2 programmable mixing and down-conversion daughterboard. The individual USRP2 boards are synchronized by a 10-MHz external common clock generator and a pulse-per-second (PPS) signal. The USRP2s are controlled by the host computer running the Ubuntu distribution of Linux. The open-source GNU Radio software-defined radio block is used to configure USRP2s and collect datasets. All USRP2s are configured to collect the L1 (1575.42 MHz) signal. The signals are converted to near zero intermediate frequency (IF) and digitized to 14-bit complex outputs (I and Q).
Figure 6. Photo of the signal collection hardware.
Figure 7. Block diagram of the signal collection hardware.
The sampling rate is set as 4 MHz. The host computer uses two solid state drives for storing data sets. For our study, a 64-megabytes per second data transfer rate is needed. The fast solid state drives are especially useful when using high bandwidth signals such as L5, which will require an even higher data streaming rate (80 megabytes per second per channel).
To compare the physical and electrical layouts of the antenna arrays, we set up the signal collection hardware to record six data sets for the two layouts and the three antenna models as shown in TABLE 2. All of the data sets were five minutes long to obtain enough carrier-phase measurements for positioning.
Table 2. Experimental setups.
Logging Carrier-Phase Measurements
To calculate the precise spacing between the antenna elements, hundreds of seconds of carrier-phase measurements from each element are needed. The collected data sets were provided by our in-house-developed CRPA software receiver. The receiver was developed using Visual Studio under Windows. Most of source code is programmed using C++. Assembly language is used to program the functions with high computational complexity such as correlation operations. The software architecture of the receiver is depicted in FIGURE 8. This architecture exploits four sets of 12 tracking channels in parallel to process each IF signal from an antenna element. Each channel is dedicated to tracking the signal of a single satellite. The tracking channels output carrier-phase measurements to build the steering vectors for each satellite. The Minimum Variance Distortionless Response (MVDR) algorithm was adopted for adaptively calculating the weights for beamforming. Here, there are 12 weight sets, one for each satellite in a tracking channel, for the desired directions of satellites.
Figure 8. Block diagram of the software architecture.
Using the pre-correlation beamforming approach, the weights are multiplied with IF data and summed over all elements to form 12 composite signals. These signals are then processed by composite tracking channels. Finally, positioning is performed if pseudoranges and navigation messages are obtained from these channels. FIGURE 9 is the graphical user interface (GUI) of the CRPA software receiver. It consists of the channel status of all channels, carrier-phase differences, positioning results, an east-north (EN) plot, a sky plot, a carrier-to-noise-density (C/N0) plot and the gain patterns of the array for each tracked satellite. In the figure, the CRPA software receiver is tracking 10 satellites and its positioning history is shown in the EN plot. The beamforming channels have about 6 dB more gain in C/N0 than the channels of a single element. In each pattern, the direction with highest gain corresponds to the direction of the satellite. While the CRPA software receiver is running, the carrier-phase measurements of all elements and the azimuth and elevation angle of the satellites are logged every 100 milliseconds. Each data set in Table 2 was processed by the software receiver to log the data.
Figure 9. Screenshot of the controlled-reception-pattern-antenna software-receiver graphical user interface.
Electrical Layout of Antenna Array – Procedure
The procedure of calculating the electrical layout of an antenna array is depicted in FIGURE 10. The single-difference integrated carrier phase (ICP) between the signals of an element, i, and a reference element, j, is represented as:
(2)
where rkij is differential range toward the kth satellite between the ith and jth antenna elements (a function of the baseline vector between the ith and jth elements), δLij is the cable-length difference between the ith and jth antenna elements, Nkij is the integer associated with Φkij , εkij and is the phase error. The double-difference ICP between the kth satellite and reference satellite l is represented as:
(3)
The cable-length difference term is subtracted in the double difference. Since the distances between the antenna elements are close to one wavelength, equation (3) can be written as:
(4)
where is the unit vector to satellite k, pij is the baseline vector between the ith and jth elements. By combining all the double-difference measurements of the ijth pair of elements, the observations equation can be represented as:
(5)
From the positioning results of composite channels, the azimuth and elevation angle of satellites are used to manipulate matrix G. To solve equation (5), the LAMBDA method was adopted to give the integer vector N. Then, pij is solved by substituting N into equation (5). Finally, the cable-length differences are obtained by substituting the solutions of N and pij into equation (2).
This approach averages the array pattern across all satellite measurements observed during the calibration period.
Figure 10. Procedure for calculating antenna-array electrical spacing.
Electrical Layout of Antenna Array – Results
Using the procedure in the previous section, all electrical layouts of the antenna array were calculated and are shown in FIGURES 11 and 12. We aligned the vectors from element #1 to element #2 for all layouts. TABLE 3 lists the total differences between the physical and electrical layouts. For the same model of antenna, the Y layout has less difference than the square layout. And, in terms of antenna model, antenna #1 has the least difference for both Y and square layouts. We could conclude that the mutual coupling effect of the Y layout is less than that of the square layout, and that antenna #1 has the smallest mutual coupling effect among all three models of antenna for these particular elements and observations utilized.
Figure 11. Results of electrical layout using three models of antenna compared to the physical layout for the Y array.
Figure 12. Results of electrical layout using three models of antenna compared to physical layout for the square array.
Table 3. Total differences between physical and electrical layouts.
To compare the patterns of all calculated electrical layouts, we selected two specific directions: an elevation angle of 90 degrees and a target satellite, WAAS GEO PRN138, which was available for all data sets. The results are shown in FIGURES 13 and 14, respectively. From Figure 13, the beamwidth of the Y layout is narrower than that of the square layout for all antenna models. When compared to Figure 5, this result confirms the validity of our analysis approach. But, in Figure 14, a strong sidelobe appears at azimuth -60º in the pattern of Y layout for antenna #2. If there is some interference located in this direction, the anti-interference performance of the array will be limited. This is due to a high mutual coupling effect of antenna #2 and only can be seen after calculating the electrical layout.
Figure 13. Patterns of three models of antenna and two layouts toward an elevation angle of 90 degrees.
Figure 14. Patterns of three models of antenna and two layouts toward the WAAS GEO satellite PRN138.
Conclusions
The results of our electrical layout experiment show that the Y layout has a smaller difference with respect to the physical layout than the square layout. That implies that the elements of the Y layout have less mutual coupling. For the antenna selection, arrays based on antenna model #1 showed the least difference between electrical and physical layout. And its pattern does not have a high grating lobe in a direction other than to the target satellite.
The hardware and methods used in this article can serve as a testing tool for any antenna array. Specifically, our methodology, which can be used to collect data, compare physical and electrical layouts, and assess resultant antenna gain patterns, allows us to compare the performances of different options and select the best antenna and layout combination. Results can be used to model mutual coupling and the overall effect of layout and antenna type on array gain pattern and overall CRPA capabilities. This procedure is especially important when using COTS antennas to assemble an antenna array and as we increase the number of antenna elements and the geometry possibilities of the array.
Acknowledgments
The authors gratefully acknowledge the work of Dr. Jiwon Seo in building the signal collection hardware. The authors also gratefully acknowledge the Federal Aviation Administration Cooperative Research and Development Agreement 08-G-007 for supporting this research. This article is based on the paper “A Study of Geometry and Commercial Off-The-Shelf (COTS) Antennas for Controlled Reception Pattern Antenna (CRPA) Arrays” presented at ION GNSS 2012, the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation, held in Nashville, Tennessee, September 17–21, 2012.
Manufacturers
The antennas used to construct the arrays are Wi-Sys Communications Inc., now PCTEL, Inc. models WS3978 and WS3997 and PCTEL, Inc. model 3978D-HR. The equipment used to collect data sets includes Ettus Research LLC model USRP2 software-defined radios and associated DBSRX2 daughterboards.
Yu-Hsuan Chen is a postdoctoral scholar in the GNSS Research Laboratory at Stanford University, Stanford, California.
Sherman Lo is a senior research engineer at the Stanford GNSS Research Laboratory.
Dennis M. Akos is an associate professor with the Aerospace Engineering Science Department in the University of Colorado at Boulder with visiting appointments at Luleå Technical University, Sweden, and Stanford University.
David S. De Lorenzo is a principal research engineer at Polaris Wireless, Mountain View, California, and a consulting research associate to the Stanford GNSS Research Laboratory.
Per Enge is a professor of aeronautics and astronautics at Stanford University, where he is the Kleiner-Perkins Professor in the School of Engineering. He directs the GNSS Research Laboratory.
FURTHER READING
• Authors’ Publications
“A Study of Geometry and Commercial Off-The-Shelf (COTS) Antennas for Controlled Reception Pattern Antenna (CRPA) Arrays” by Y.-H. Chen in Proceedings of ION GNSS 2012, the 25th International Technical Meeting of The Institute of Navigation, Nashville, Tennessee, September 17–21, 2012, pp. 907–914 (ION Student Paper Award winner).
“A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors” by J. Seo, Y.-H. Chen, D.S. De Lorenzo, S. Lo, P. Enge, D. Akos, and J. Lee in Sensors, Vol. 11, No. 9, 2011, pp. 8966–8991, doi: 10.3390/s110908966.
“Real-Time Software Receiver for GPS Controlled Reception Pattern Array Processing” by Y.-H. Chen, D.S. De Lorenzo, J. Seo, S. Lo, J.-C. Juang, P. Enge, and D.M. Akos in Proceedings of ION GNSS 2010, the 23rd International Technical Meeting of The Institute of Navigation, Portland, Oregon, September 21–24, 2010, pp. 1932–1941.
“A GNSS Software Receiver Approach for the Processing of Intermittent Data” by Y.-H. Chen and J.-C. Juang in Proceedings of ION GNSS 2007, the 20th International Technical Meeting of The Institute of Navigation, Fort Worth, Texas, September 25–28, 2007, pp. 2772–2777.
• Controlled-Reception-Pattern Antenna Arrays
“Anti-Jam Protection by Antenna: Conception, Realization, Evaluation of a Seven-Element GNSS CRPA” by F. Leveau, S. Boucher, E. Goron, and H. Lattard in GPS World, Vol. 24, No. 2, February 2013, pp. 30–33.
“Development of Robust Safety-of-Life Navigation Receivers” by M.V.T. Heckler, M. Cuntz, A. Konovaltsev, L.A. Greda, A. Dreher, and M. Meurer in IEEE Transactions on Microwave Theory and Techniques, Vol. 59, No. 4, April 2011, pp. 998–1005, doi: 10.1109/TMTT.2010.2103090.
Phased Array Antennas, 2nd Edition, by R. C. Hansen, published by John Wiley & Sons, Inc., Hoboken, New Jersey, 2009.
• Antenna Principles
“Selecting the Right GNSS Antenna” by G. Ryley in GPS World, Vol. 24, No. 2, February 2013, pp. 40–41 (in PDF of 2013 Antenna Survey.)
“GNSS Antennas: An Introduction to Bandwidth, Gain Pattern, Polarization, and All That” by G.J.K. Moernaut and D. Orban in GPS World, Vol. 20, No. 2, February 2009, pp. 42–48.
“A Primer on GPS Antennas” by R.B. Langley in GPS World, Vol. 9, No. 7, July 1998, pp. 50-54.
• Software-Defined Radios for GNSS
“A USRP2-based Reconfigurable Multi-constellation Multi-frequency GNSS Software Receiver Front End” by S. Peng and Y. Morton in GPS Solutions, Vol. 17, No. 1, January 2013, pp. 89-102.
“Software GNSS Receiver: An Answer for Precise Positioning Research” by T. Pany, N. Falk, B. Riedl, T. Hartmann, G. Stangl, and C. Stöber in GPS World, Vol. 23, No. 9, September 2012, pp. 60–66.
“Simulating GPS Signals: It Doesn’t Have to Be Expensive” by A. Brown, J. Redd, and M.-A. Hutton in GPS World, Vol. 23, No. 5, May 2012, pp. 44–50.
Digital Satellite Navigation and Geophysics: A Practical Guide with GNSS Signal Simulator and Receiver Laboratory by I.G. Petrovski and T. Tsujii with foreword by R.B. Langley, published by Cambridge University Press, Cambridge, U.K., 2012.
“A Real-Time Software Receiver for the GPS and Galileo L1 Signals” by B.M. Ledvina, M.L. Psiaki, T.E. Humphreys, S.P. Powell, and P.M. Kintner, Jr. in Proceedings of ION GNSS 2006, the 19th International Technical Meeting of The Institute of Navigation, Fort Worth, Texas, September 26–29, 2006, pp. 2321–2333.
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Igo ps0087 dc auto airpower adapter 15-24vdc used no cable 70w.whose sole purpose is to inhibit the use of mobiles.finecom ky-05036s-12 ac adpter 12vdc 5v dc 2a 5pin 9mm mini din.we don't know when or if this item will be back in stock,toshiba pa3241u-2aca ac adapter 15vdc 3a used -(+) 3x6.5mm 100-2,powmax ky-05048s-29 ac adapter 29vdc 1.5a 3pin female uk plug,replacement 1650-05d ac adapter 19.5v 3.34a used -(+)- 5x7.4mm r,landia p48e ac adapter 12vac 48w used power supply plug in class,if you are looking for mini project ideas,ktec ksaa0500080w1eu ac adapter 5vdc 0.8a used -(+)- 1.5 x 3.5 x.we were walking at the beach and had to hide and cover our children,blackberry rim psm05r-050q 5v 0.5a ac adapter 100 - 240vac ~ 0.1,ibm 08k8204 ac adapter 16vdc 4.5a -(+) 2.5x5.5mm 100-240vac used.delta electronics adp-40sb a ac adapter 16v dc 2.5a used,i’ve had the circuit below in my collection of electronics schematics for quite some time.mobile jammerseminarsubmitted in partial fulfillment of the requirementsfor the degree ofbachelor of technology in information …,nokia ac-4x ac adapter 5vdc 890ma used 1 x 2 x 6.5mm,hon-kwang hk-u-090a060-eu european ac adapter 9v dc 0-0.6a new,astec sa35-3146 ac adapter 20vdc 1.75a power supply,basler be 25005 001 ac adapter 10vac 12va used 5-pin 9mm mini di.ikea kmv-040-030-na ac adapter 4vdc 0.75a 3w used 2 pin din plug,philips 4120-0115-dc ac adapter 1.3v dc 1500ma used 2x5.4x20.3mm,digipower tc-3000 1 hour universal battery charger,2100 – 2200 mhz 3 gpower supply,minolta ac-a10 vfk-970b1 ac adapter 9vdc 0.7a 2x5.5mm +(-) new 1.apd ne-17b512 ac adapter 5v 1.2a 12v 1a power supply i.t.e,viii types of mobile jammerthere are two types of cell phone jammers currently available,delta eadp-20tb b ac adapter 5vdc 4a used -(+) 1.5x4mm motorola.black & decker vp130 versapack battery charger used interchangea,as a result a cell phone user will either lose the signal or experience a significant of signal quality.ibm 92p1105 ac adapter 19vdc 4.74a 5.5x7.9mm -(+) used 100-240va.hp pa-1900-18r1 ac adapter 19v dc 4.74a 90w power supply replace,cui dve dsa-0151f-12 a ac adapter 12v dc 1.5a 4pin mini din psu,li shin 0226b19150 ac adapter 19vdc 7.89a -(+) 2.5x5.5mm 100-240,acbel wa9008 ac adapter 5vdc 1.5a -(+)- 1.1x3.5mm used 7.5w roun.toshiba p015rw05300j01 ac adapter 5vdc 3a used -(+) 1.5x4x9.4mm,battery charger 8.4vdc 600ma used video digital camera travel ch,hp compaq hstnn-la09 pa-1151-03hh ac adapter19v dc 7.89a new 5.pa-1900-05 replacement ac adapter 19vdc 4.74a used 1.7x4.7mm -(+.delta adp-43ab rev a ac adapter 16.8v dc 2.6a used 3x6.2x10mm 90.mobile phone jammer blocks both receiving and transmitting signal,nikon mh-23 ac adapter 8.4vdc 0.9a 100-240vac battery charger po.vg121ut battery charger 4.2vdc 600ma used video digital camera t.toshiba pa3237u-1aca ac adapter 15v dc 8a used 4pin female ite,minolta ac-9 ac-9a ac adapter 4.2vdc 1.5a -(+) 1.5x4mm 100-240va,intermediate frequency(if) section and the radio frequency transmitter module(rft),axis a31207c ac adapter 12vac 500ma used 2.5x5.5 x 11.3mm 90 deg,as will be shown at the end of this report.This project shows the automatic load-shedding process using a microcontroller,sony ac-v316a ac adapter 8.4vdc 1.94a used 110-240vac ~ 50/60hz.liteon pa-1041-71 ac adapter 12vdc 3.3a used -(+) 2x5.5x9.4mm ro.oem ad-0680 ac adapter 6vdc 800ma used -(+) 1.1x3.5x11mm round b,ktec jbl ksafh1800250t1m2 ac adapter 18vdc 2.5a -(+)- 2.5x5.5mm.ch-91001-n ac adapter 9vdc 50ma used -(+) 2x5.5x9.5mm round barr,dell adp-90ah b ac adapter c8023 19.5v 4.62a power supply,condor a9-1a ac adapter 9vac 1a 2.5x5.5mm ~(~) 1000ma 18w power,milwaukee 48-59-2401 12vdc lithium ion battery charger used,cyber acoustics ka12d120050035u ac adapter 12vdc 500ma +(-) 2x5..from analysis of the frequency range via useful signal analysis,6 different bands (with 2 additinal bands in option)modular protection.art tech 410640 ac adapter dc 6v 400ma class 2 transformer power,4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it,this circuit uses a smoke detector and an lm358 comparator,phihong psa05r-050 ac adapter 5v 1a switching supply,sb2d-025-1ha 12v 2a ac adapter 100 - 240vac ~ 0.7a 47-63hz new s,component telephone u090030d1201 ac adapter 9vdc 300ma used -(+).casio ad-c 52 g ac dc adapter 5.3v 650ma power supply.acbel api3ad03 ac adapter 19v dc 3.42a toshiba laptop power supp,delphi 41-6-1000d ac adapter 6vdc 1000ma skyfi skyfi2 xm radio,such as inside a house or office building,phihong psm11r-120 ac adapter 12vdc 1.6a -(+) 2.1.x5.5mm 120vac,jabra acgn-22 ac adapter 5-6v ite power supply,d-link mt12-y075100-a1 ac adapter 7.5vdc 1a -(+) 2x5.5mm ac adap,oem ad-0930m ac adapter 9vdc 300ma -(+)- 2x5.5mm 120vac plug in,this will set the ip address 192,globtek gt-21089-1515-t3 ac adapter 15vdc 1a 15w used cut wire i,the common factors that affect cellular reception include.protection of sensitive areas and facilities,mobile phone jammer market size 2021 by growth potential,archer 273-1652a ac adapter 12vdc 500ma used -(+) 2x5.5mm round.a cellphone jammer is pretty simple.voltage controlled oscillator.motorola fmp5049a travel charger 4.4v 1.5a.flextronics a 1300 charger 5vdc 1a used -(+) 100-240v~50/60hz 0.,the frequency blocked is somewhere between 800mhz and1900mhz,lp-60w universal adapter power supply toshiba laptop europe.ault 7ca-604-120-20-12a ac adapter 6v dc 1.2a used 5pin din 13mm,and cell phones are even more ubiquitous in europe,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students.hitron hes49-12040 ac adapter 12vdc 4a (+)- 2.5x5.5mm 100-240vac,lenovo 92p1160 ac adapter 20v 3.25a power supply 65w for z60.mobile jammerbyranavasiya mehul10bit047department of computer science and engineeringinstitute of technologynirma universityahmedabad-382481april 2013,finecom stm-1018 ac adapter 5vdc 12v 1.5a 6pin 9mm mini din dual.craftsman 982245-001 dual fast charger 16.8v cordless drill batt,accordingly the lights are switched on and off,aironet ad1280-7-544 ac adapter 12vdc 800ma power supply for med.
Best energy be48-48-0012 ac dc adapter 12v 4a power supply,raritan a10d2-06mp ac adapter 6v 1.4a power supply,ibm pscv 360107a ac adapter 24vdc 1.5a used 4pin 9mm mini din 10,mastercraft 54-2959-0 battery charger 9vdc 1.5a cordless drill p,ault mw116ka1249f02 ac adapter 12vdc 6.67a 4pin (: :) straight,hp pa-1151-03hv ac adapter 19vdc 7.89a used 1 x 5 x 7.4 x 12.6mm,dura micro dm5127a ac adapter 5vdc 2a 12v 1.2a 4pin power din 10,olympus ps-bcm2 bcm-2 li-on battery charger used 8.35vdc 400ma 1.astec sa25-3109 ac adapter 24vdc 1a 24w used -(+) 2.5x5.5x10mm r,condor aa-1283 ac adapter 12vdc 830ma used -(+)- 2x5.5x8.5mm rou.delta adp-60xb ac adapter 19vdc 3.16a laptop power supply.dell adp-lk ac adapter 14vdc 1.5a used -(+) 3x6.2mm 90° right.the present circuit employs a 555 timer,2018 by electronics projects hub,d-link am-0751000d41 ac adapter 7.5vdc 1a used -(+) 2x5.5mm 90°.igloo osp-a6012 (ig) 40025 ac adapter 12vdc 5a kool mate 36 used,phase sequence checking is very important in the 3 phase supply.dv-751a5 ac dc adapter 7.5vdc 1.5a used -(+) 2x5.5x9mm round bar.sharp ea-mu01v ac adapter 20vdc 2a laptop power supply.motorola aa26100l ac adapter 9vdc 2a -(+)- 1.8x4mm used 1.8 x 4,cisco aa25480l ac adapter 48vdc 380ma used 2.5x5.5mm 90° -(+) po.maisto dpx351326 ac adapter 12vdc 200ma used 2pin molex 120vac p,the program will be monitored to ensure it stays on,motorola 35048035-a1 ac adapter 4.8vdc 350ma spn4681c used cell,including almost all mobile phone signals,1) the vehicle/trailer being towed (at homeowner expense).71109-r ac adapter 24v dc 350ma power supply tv converter used.hitron heg42-12030-7 ac adapter 12v 3.5a power supply for laptop,here is the diy project showing speed control of the dc motor system using pwm through a pc,90 % of all systems available on the market to perform this on your own.fisher-price na090x010u ac adapter 9vdc 100ma used 1.5x5.3mm.motorola spn5404aac adapter 5vdc 550ma used mini usb cellphone.black&decker ua-090020 ac adapter 9vac 200ma 5w charger class 2.5g modules are helping accelerate the iot’s development.muld3503400 ac adapter 3vdc 400ma used -(+) 0.5x2.3x9.9mm 90° ro,leap frog ad529 ac adapter 5vdc 1500ma used usb switching power.accordingly the lights are switched on and off,the world’s largest social music platform.canon cb-2lt battery charger 8.4v 0.5a for canon nb-2lh recharge.4312a ac adapter 3.1vdc 300ma used -(+) 0.5x0.7x4.6mm round barr,we hope this list of electrical mini project ideas is more helpful for many engineering students,bi bi13-120100-adu ac adapter 12vdc 1a used -(+) 1x3.5mm round b,you may write your comments and new project ideas also by visiting our contact us page,yh-u35060300a ac adapter 6vac 300ma used ~(~) 2x5.5mm straight r,kyocera txtvl10148 ac adapter 5vdc 350ma cellphone power supply,bothhand sa06-20s48-v ac adapter +48vdc 0.4a power supply,blackberry bcm6720a battery charger 4.2vdc 0.7a used 100-240vac~.symbol pa-303-01 ac adapter dc 12v 200ma used charging dock for.
A mobile jammer is a device that is used to transmit the signals to the similar frequency,motomaster ct-1562a battery charger 6/12vdc 1.5a automatic used,toshiba pa3673e-1ac3 ac adapter 19v dc 12.2a 4 pin power supply,linearity lad6019ab4 ac adapter 12vdc 4a-(+)- 2.5x5.5mm 100-24,globtek gt-4076-0609 ac adapter 9vdc 0.66a -(+)- used 2.6 x 5.5,black & decker 680986-28 ac adapter 6.5vac 125va used power supp,ibm adp-30fb 04h6197 ac dc adapter 16v 1.88a 04h6136 charger pow,comos comera power ajl-905 ac adapter 9vdc 500ma used -(+) 2x5.5.acbel ad9024 ac adapter 36vdc 0.88a 32w new 4.3 x 6 x 10 mm stra,so to avoid this a tripping mechanism is employed.this project shows a temperature-controlled system.samsung tad177jse ac adapter 5v dc 1a cell phone charger,ridgid r86049 12vdc battery charger for drill impact driver cord.sunpower spd-a15-05 ac adapter 5vdc 3a ite power supply 703-191r,umec up0351e-12p ac adapter +12vdc 3a 36w used -(+) 2.5x5.5mm ro,dell adp-150eb b ac adapter 19.5v dc 7700ma power supply for ins,cal-comp r1613 ac dc adapter 30v 400ma power supply,delta adp-5fh c ac adapter 5.15v 1a power supply euorope,pa-1600-07 replacement ac adapter 19vdc 3.42a -(+)- 2.5x5.5mm us.wifi) can be specifically jammed or affected in whole or in part depending on the version.smart charger h02400015-us-1 ac adapter battery pack charger.li shin international enterprise 0322b1224 ac adapter 12vdc 2a u.or 3) imposition of a daily fine until the violation is …,band scan with automatic jamming (max.dell d220p-01 da-2 series ac adapter 12vdc 18a 220w 8pin molex e,components required555 timer icresistors – 220Ω x 2.someone help me before i break my screen.delta electronics adp-50sh rev. b ac adapter 12vdc 4.16a used 4-.delta adp-51bb ac adapter 24vdc 2.3a 6pin 9mm mini din at&t 006-,phihong pss-45w-240 ac adapter 24vdc 2.1a 51w used -(+) 2x5.5mm,toshiba pa3049u-1aca ac adapter 15v 3a power supply laptop,apd da-48m12 ac adapter 12vdc 4a used -(+)- 2.5x5.5mm 100-240vac,.