Photo: Galileo
Analysis of new Galileo signals at an experimental ground-based augmentation system (GBAS) compares noise and multipath in their performance to GPS L1 and L5. Raw noise and multipath level of the Galileo signals is shown to be smaller than those of GPS. Even after smoothing, Galileo signals perform somewhat better than GPS and are less sensitive to the smoothing time constant.
By Mihaela-Simona Circiu, Michael Felux, German Aerospace Center (DLR), and Sam Pullen, Stanford University
Several ground-based augmentation system (GBAS) stations have become operational in recent years and are used on a regular basis for approach guidance. These include airports at Sydney, Malaga, Frankfurt and Zurich. These stations are so-called GBAS Approach Service Type C (GAST C) stations and support approaches only under CAT-I weather conditions; that is, with a certain minimum visibility. Standards for stations supporting CAT-II/III operations (low visibility or automatic landing, called GAST D), are expected to be agreed upon by the International Civil Aviation Organization (ICAO) later this year. Stations could be commercially available as soon as 2018.
However, for both GAST C and D, the availability of the GBAS approach service can be significantly reduced under active ionospheric conditions. One potential solution is the use of two frequencies and multiple constellations in order to be able to correct for ionospheric impacts, detect and remove any compromised satellites, and improve the overall satellite geometry (and thus the availability) of the system.
A new multi-frequency and multi-constellation (MFMC) GBAS will have different potential error sources and failure modes that have to be considered and bounded. Thus, all performance and integrity assumptions of the existing single-frequency GBAS must be carefully reviewed before they can be applied to an MFMC system. A central element for ensuring the integrity of the estimated position solution is the calculation of protection levels. This is done by modeling all disturbances to the navigation signals in a conservative way and then estimating a bound on the resulting positioning errors that is valid at an allocated integrity risk probability.
One of the parameters that is different for the new signals and must be recharacterized is the residual uncertainty attributed to the corrections from the ground system (σpr_gnd). A method to assess the contribution of residual noise and multipath is by evaluating the B-values in GBAS, which give an estimate of the error contribution from a single reference receiver to a broadcast correction. Independent data samples over at least one day (for GPS) are collected and sorted by elevation angle. Then the mean and standard deviations for each elevation bin are determined.
Here, we evaluate the E1 and E5a signals broadcast by the operational Galileo satellites now in orbit. In the same manner as we did for GPS L5 in earlier research, we determine the σpr_gnd values for these Galileo signals. As for GPS L5, results show a lower level of noise and multipath in unsmoothed pseudorange measurements compared to GPS L1 C/A code.
DLR GBAS Facility
DLR has set up a GBAS prototype at the research airport in Braunschweig (ICAO identifier EDVE) near the DLR research facility there. This ground station has recently been updated and now consists of four GNSS receivers connected to choke ring antennas, which are mounted at heights between 2.5 meters and 7.5 meters above equipment shelters. All four receivers are capable of tracking GPS L5 (in addition to GPS L1 and L2 semi-codeless) and Galileo E1 and E5a signals. Figure 1 gives an overview of the current ground station layout, and Table 1 gives the coordinates of the antennas.
Figure 1. DLR ground facility near Braunschweig Airport, also shown in opening photo at left.
Table 1. Ground receiver antenna coordinates.
Smoothing Techniques
The GBAS system corrects for the combined effects of multiple sources of measurement errors that are highly correlated between reference receivers and users, such as satellite clock, ephemeris error, ionospheric delay error, and tropospheric delay error, through the differential corrections broadcast by the GBAS ground subsystem. However, uncorrelated errors such as multipath and receiver noise can make a significant contribution to the remaining differential error. Multipath errors are introduced by the satellite signal reaching the antenna via both the direct path from the satellites and from other paths due to reflection. These errors affect both the ground and the airborne receivers, but are different at each and do not cancel out when differential corrections are applied.
To reduce these errors, GBAS performs carrier smoothing. Smoothing makes use of the less noisy but ambiguous carrier-phase measurements to suppress the noise and multipath from the noisy but unambiguous code measurements.
The current GBAS architecture is based on single-frequency GPS L1 C/A code measurements only. Single-frequency carrier smoothing reduces noise and multipath, but ionospheric disturbances can cause significant differential errors when the ground station and the airborne user are affected by different conditions. With the new available satellites (GPS Block IIF and Galileo) broadcasting in an additional aeronautical band (L5 / E5), this second frequency could be used in GBAS to overcome many current limitations of the single-frequency system.
Dual-frequency techniques have been investigated in previous work. Two dual-frequency smoothing algorithms, Divergence Free (Dfree) and Ionosphere Free (Ifree), have been proposed to mitigate the effect of ionosphere gradients.
The Dfree output removes the temporal ionospheric gradient that affects the single-frequency filter but is still affected by the absolute difference in delay created by spatial gradients. The main advantage of Dfree is that the output noise is similar to that of single-frequency smoothing, since only one single-frequency code measurement is used as the code input (recall that carrier phase noise on both frequencies is small and can be neglected).
Ifree smoothing completely removes the (first-order) effects of ionospheric delay by using ionosphere-free combinations of code and phase measurements from two frequencies as inputs to the smoothing filter. Unlike the Dfree, the Ifree outputs contain the combination of errors from two code measurements. This increases the standard deviation of the differential pseudorange error and thus also of the position solution.
Noise and Multipath in New GNSS Signals
GBAS users compute nominal protection levels (H0) under a fault-free assumption. These protection levels are conservative overbounds of the maximum position error after application of the differential corrections broadcast by the ground system, assuming that no faults or anomalies affect the position solution. In order to compute these error bounds, the total standard deviation of each differentially corrected pseudorange measurements has to be modeled. The standard deviation of the residual uncertainty (σn, for the nth satellite) consists of the root-sum-square of uncertainties introduced by atmospheric effects (ionosphere, troposphere) as well as of the contribution of the ground multipath and noise. In other words, these error components are combined to estimate σn2 as described in the following equation:
(1)
The ground broadcasts a value for σpr_gnd (described later in the section) associated with the pseudorange correction for each satellite. These broadcast values are based on combinations of theoretical models and actual measurements collected from the ground receivers that represent actual system characteristics. Unlike the ground, σpr_air is computed based entirely on a standardized error model. This is mainly to avoid the evaluation of multipath for each receiver and each aircraft during equipment approval.
In addition to the characteristics of nearby signal reflectors, multipath errors are mainly dependent on signal modulation and other signal characteristics (for example, power, chip rate). In earlier research, we showed that the newly available L5 signals broadcast by the GPS Block IIF satellites show better performance in terms of lower noise and multipath. This mainly results from an increased transmitted power and a 10 times higher chip rate on L5 compared to the L1 C/A code signal.
In this work, we extend this evaluation to the new Galileo signals and investigate their impact on a future multi-frequency, multi-constellation GBAS. Characterization of these new signals is based on ground subsystem measurements, since no flight data with GPS L5 or Galileo measurements are available at the moment. We assume that the improvements observed by ground receivers are also applicable to airborne measurements. This assumption will be validated as soon as flight data are available.
The measurements used were collected from the DLR GBAS test bed over 10 days (note that Galileo satellite ground track repeatability is 10 sidereal days) between the December 14 and 23, 2013. In that period, four Galileo and four Block IIF GPS satellites were operational and broadcast signals on both aeronautical bands E1 / L1 and E5a / L5.
In Figure 2, the suppression of multipath and noise on the Galileo signals can be observed, where the code multipath and noise versus elevation for GPS L1 C/A BSPK(1), Galileo E1 (BOC (1,1)) and Galileo E5a (BPSK(10)) signals are shown. The code multipath and noise was estimated using the linear dual-frequency combination described in equation (2), where MPi represents the code multipath and noise on frequency i, ρi the code measurement, and ϕi,and ϕj represent the carrier-phase measurements on frequencies i and j, respectively. Carrier phase noises are small and can be neglected.
(2)
Figure 2. Raw multipath function of elevation for GPS L1, Galileo E1 (BOC (1,1)) and Galileo E5a (BPSK(10)) signals.
The multipath on the Galileo E1 (BOC(1,1)) signal (the magenta curve) is lower than the GPS L1 C/A (BPSK(1)) (black curve), especially for low elevation, where the advantage of the E1 BOC(1,1) is more pronounced. The lower values can be explained by the wider transmission bandwidth on E1 and the structure of the BOC signal. Galileo E5a (green data in Figure 2) again shows a better performance than Galileo E1. This was expected due to the higher chip rate and higher signal power. A comparison of the raw multipath and noise standard deviations for GPS L1, L5 and Galileo E1, E5a signals is presented in Figure 3.
Figure 3. Ratios of the multipath and noise standard deviation function of elevation.
The curves there show the ratios of the standard deviations for each elevation bin. The values for GPS L1 are almost 1.5 times larger than those for Galileo E1 BOC(1,1) (green curve) for elevations below 20°. For high elevations, the ratio approaches 1.0. This corresponds to the observations in the raw multipath plot ( Figure 2). With the same signal modulation and the same chip rate, E5a and L5 have very similar results (red curve), and the ratio stays close to 1.0 for all elevations.
The blue and the purple curves in Figure 3 show the ratio of GPS L1 C/A (BPSK(1)) and GPS L5 (BPSK(10)), and Galileo E1 (BOC(1,1)) and Galileo E5a (BPSK(10)), respectively. The ratio of GPS L1 to GPS L5 (blue curve) increases with elevation from values around 2.5 for low elevations, reaching values above 3.5 for elevations higher than 60°. As Galileo E1 performs better, the ratio between Galileo E1 and Galileo E5a (purple curve) is smaller, from a value of 1.5 for elevations below 10 degrees to a value of 3.0 for high elevations.
Until now, we have presented the evaluation of raw code noise and multipath. However, in GBAS, carrier smoothing is performed to minimize the effect of code noise and multipath. The value that describes the noise introduced by the ground station is represented by a standard deviation called σpr_gnd and is computed based on the smoothed pseudoranges from the reference receivers. In the following section, we focus on the evaluation of σpr_gnd using different signals and different smoothing time constants. Note that, in this study, σpr_gnd contains only smoothed multipath and noise; no other contributions (for example, inflation due to signal deformation or geometry screening) are considered.
B-values and σpr_gnd
B-values represent estimates of the associated noise and multipath with the pseudorange corrections provided from each receiver for each satellite, as described in Eurocae ED-114A and RTCA DO-253C. They are used to detect faulty measurements in the ground system. For each satellite-receiver pair B(i,j), they are computed as:
(3)
where PRCTX represents the candidate transmitted pseudorange correction for satellite i (computed as an average over all M(i) receivers), and PRCSCA(i,k) represents the correction for satellite i from receiver k after smoothed clock adjustment, which is the process of removing the individual receiver clock bias from each reference receiver and all other common errors from the corrections. The summation computes the average correction over all M(k) receivers except receiver j. This allows detection and exclusion of receiver j if it is faulty. If all B-values are below their thresholds, the candidate pseudorange correction PRCTX is approved and transmitted. If not, a series of measurement exclusions and PRC and B-value recalculations takes place until all revised B-values are below threshold. Note that, under nominal conditions using only single-frequency measurements, the B-values are mainly affected by code multipath and noise.
Under the assumption that multipath errors are uncorrelated across reference receivers, nominal B-values can be used to assess the accuracy of the ground system. The standard deviation of the uncertainty associated with the contribution of the corrections (σpr_gnd) for each receiver m is related to the standard deviation of the B-values by:
(4)
where M represents the number of the receivers and N represents the number of satellites used. The final sigma takes into account the contribution from all receivers and is computed as the root mean square of the standard deviation of the uncertainties associated with each receiver (Equation 4).
Figure 4 shows the evaluation of (σpr_gnd) for the Galileo E1, BOC(1,1) signal and the GPS L1 C/A signal for increasing smoothing time constants (10, 30, 60, and 100 seconds). Starting with a 10-second smoothing constant, Galileo E1 shows much better performance than GPS L1. The difference shrinks as the smoothing constant increases due to the effectiveness of smoothing in reducing noise and short-delay multipath. However, even with 100-second smoothing (the purple curves), Galileo E1 BOC(1,1) shows lower values of (σpr_gnd).
Figure 4. σ(pr_gnd) versus elevation for Galileo E1 (dotted lines) and GPS L1 (solid lines for different smoothing constants: red (10s), green (30s), cyan (60s), purple (100s).
A similar comparison is presented in Figure 5, of the performance of GPS L1 and Galileo E5a. The Galileo E5a signal is significantly less affected by multipath, and the difference stays more pronounced than in the Galileo E1 – GPS L1, even with 100-second smoothing. It can be also observed that the Galileo signals have a lower sensitivity to the smoothing constant. The Galileo E1 signal shows an increase of sensitivity for low elevations (below 40°), while on E5a, a smoothing constant larger than 10 seconds has almost no impact on the residual error. Thus, a shorter smoothing constant on Galileo E5a generates approximately the same residual noise and multipath a 100-second smoothing constant on GPS L1.
Figure 5. σ(pr_gnd) versus elevation for Galileo E5a (dotted lines) and GPS L1 (solid lines) for different smoothing constants: red (10s), green (30s), cyan (60s), purple (100s).
The values for (σpr_gnd) are, however, impacted by the number of satellites which are used to determine a correction. Since only a very limited number of satellites broadcasting L5 and Galileo signals are currently available, these results should be considered preliminary. The first evaluations strongly indicate that with the new signals, we get better ranging performance. Based on the performance advantage of the new signals, a decrease of the smoothing constant is one option for future application. This would reduce the time required (for smoothing to converge) before including a new satellite or re-including a satellite after it was lost.
In the current GAST-D implementation, based on GPS L1 only, guidance is developed based on a 30-second smoothing time constant. A second solution, one with 100 seconds of smoothing, is used for deriving the Dv and Dl parameters from the DSIGMA monitor and thus for protection level bounding (it is also used for guidance in GAST-C). During the flight, different flight maneuvers or the blockage by the airframe can lead to the loss of the satellite signal.
Figure 6 shows the ground track of a recent flight trial conducted by DLR in November 2014. The colors represent the difference between the number of satellites used by the ground subsystem (with available corrections) and the number of satellites used by the airborne subsystem in the GAST-D position solution. One of the purposes of the flight was to characterize the loss of satellite signals in turns. In turns with a steeper bank angle, up to 3 satellites are lost (Turns 1, 3, and 4), while on a wide turn with a small bank angle (Turn 2), no loss of satellite lock occurred. It is also possible for airframe to block satellite signals, leading to a different number of satellites between ground and airborne even without turns.
Figure 6. Ground track of a flight trial conducted by DLR. The colors represent difference between number of SVs used by the ground system and number of SVs used by the airborne.
With this in mind, a shorter smoothing constant would allow the satellites lost to turns or to airframe blockage to be re-included more rapidly in the position solution. However, a new smoothing constant would have to be validated with a larger amount of data. Data from flights trials has to be evaluated as well to confirm that similar levels of performance are reresentative of the air multipath and noise.
In a future dual-frequency GBAS implementation, an important advantage of lower multipath and noise is to improve the Ifree position solution. In earlier research, we demonstrated that the error level of the Dfree solution is almost the same as for single-frequency, but an increase in error by a factor of 2.33 was computed for the Ifree standard deviation based on L1 C/A code and L2 semi-codeless measurements.
If the errors on L1 (E1) and L5 (E5a) code and carrier phase measurements are statistically independent the standard deviation of the σIfree can be written as,
(5)
where α=1−f 21 ∕ f 25, and σL1,σL5 represent the standard deviations of the smoothed noise and multipath for L1 (E1) and L5 (E5a), respectively. Considering σpr_gnd,L1(E1)) = σpr_gnd,L5(E5a)) in equation (5), the noise and multipath error on Ifree (σIfree) increases by a factor of 2.59.
Figure 7 shows the ratio σIfree/σL1 using measured data. We observe that the measured ratio (the black curve) is below the theoretical ratio computed based on the assumption of statistically independent samples (the constant value of 2.59). This is explained by the fact that the multipath errors in the measurements are not independent but have some degree of statistical correlation. The standard deviations are computed based on the same data set used in the raw multipath and noise assessment using 100-second smoothed measurements sorted into elevation bins of 10° spacing.
Figure 7. Measured ratio σIfree/σL1 function of elevation.
Conclusion
We have shown how GBAS can benefit from the new signals provided by the latest generation of GPS and Galileo satellites. We have demonstrated improved performance in terms of lower noise and multipath in data collected in our GBAS test bed. When GBAS is extended to a multi-frequency and multi-constellation system, these improvements can be leveraged for improved availability and better robustness of GBAS against ionospheric and other disturbances.
Acknowledgment
Large portions of this work were conducted in the framework of the DLR internal project, GRETA.
Manufacturers
The ground facility consists of four JAVAD GNSS Delta receivers, all connected to Leica AR 25 choke ring antennas.
Mihaela-Simona Circiu is is a research associate at the German Aerospace Center (DLR). Her research focuses on multi-frequency multi-constellation Ground Based Augmentation System. She obtained a 2nd level Specialized Master in Navigation and Related Applications from Politecnico di Torino.
MIchael Felux is is a research associate at the German Aerospace Center (DLR). He is coordinating research in the field of ground-based augmentation systems and pursuing a Ph.D. in Aerospace Engineering at the Technische Universität München.
Sam Pullen is a senior research engineer at Stanford University, where he is the director of the Local Area Augmentation System (LAAS) research effort. He has supported the FAA and others in developing GNSS system concepts, requirements, integrity algorithms, and performance models since obtaining his Ph.D. from Stanford in Aeronautics and Astronautics.
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| guns jamming p-51b eto | 3095 | 5433 | 6486 |
| walkie talkie sale | 8152 | 8732 | 1575 |
| dcs phs | 4780 | 3424 | 1826 |
| jamming meaning name samuel | 6681 | 3802 | 612 |
| jamming meaning name thomas | 1307 | 2789 | 831 |
| jamming meaning name valerie | 3969 | 1972 | 5962 |
Oem ads18b-w120150 ac adapter 12vdc 1.5a -(+)- 2.5x5.5mm i.t.e.,artestyn ssl10-7660 ac dc adapter 91-58349 power supply 5v 2a,here is the project showing radar that can detect the range of an object.phihong psa05r-033 ac adapter +3.3vdc +(-) 1.2a 2x5.5mm new 100-,load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit.gold peak automobile adapter 15vdc 4a used 2.5x5.5mm 11001100331,l0818-60b ac adapter 6vac 600ma used 1.2x3.5x8.6mm round barrel,brother ad-20 ac adapter 6vdc 1.2a used -(+) 2x5.5x9.8mm round b,sino-american sa120a-0530v-c ac adapter 5v 2.4a new class 2 powe.– active and passive receiving antennaoperating modes.aps ad-530-7 ac adapter 8.4vdc 7 cell charger power supply 530-7.basically it is an electronic countermeasure device,set01b electronic transformer 12vac 105w 110vac crystal halogen,matewell 41-18-300 ac adapter 18vdc 300ma used -(+) 1x3.4x9.9mm.mobile jammers effect can vary widely based on factors such as proximity to towers,liteon pa-1300-04 ac adapter 19vdc 1.58a laptop's power supply f,automatic telephone answering machine.delta adp-51bb ac adapter +24v-2.3a -(+) 2.5x5.5mm 230367-001 po,hp f1044b ac adapter 12vdc 3.3a adp-40cb power supply hp omnibo,one of the important sub-channel on the bcch channel includes.car adapter charger used 3.5mm mono stereo connector,finecom i-mag 120eu-400d-1 ac adapter 12vdc 4a -(+) 1.7x4.8mm 10.cte 4c24040a charger ac adapter 24vdc 4a 96w used 3pin xlr power.remington ms3-1000c ac dc adapter 9.5v 1.5w power supply.this circuit shows a simple on and off switch using the ne555 timer,usually by creating some form of interference at the same frequency ranges that cell phones use,linksys mt10-1050200-a1 ac adapter 5v 2a switching power supply.bml 163 020 r1b type 4222-us ac adapter 12vdc 600ma power supply.the pki 6025 is a camouflaged jammer designed for wall installation,atlinks 5-2495a ac adapter 6vdc 300ma used -(+) 2.5x5.5x12mm rou,zip drive ap05f-uv ac adapter 5vdc 1a used -(+)- 2.4 x 5.4 x 10.li shin lse9901b1260 ac adapter12vdc 5a 60w used 4pin din power.
Finecom py-398 ac adapter 5v dc 2000ma 1.3 x 3.5 x 9.8mm,ibm 07h0629 ac adapter 10vdc 1a used -(+)- 2 x 5 x 10 mm round b,the if section comprises a noise circuit which extracts noise from the environment by the use of microphone.tpv adpc12416ab ac adapter 12v 4.16a acer notebook power supply.edac premium power pa2444u ac adapter 13v dc 4a -(+)- 3x6.5mm 10.lishin lse0202c1990 ac adapter 19v 4.74a laptop power supply,compaq ppp003s ac adapter 18.5vdc 2.7a -(+) 1.5x4.75cm 100-240va,35a-d06-500 ac adapter 6vdc 500ma 3va used 1 x 2.4 x 9.4mm,this device is the perfect solution for large areas like big government buildings,airspan pwa-024060g ac adapter 6v dc 4a charger,compaq2882 213563-001 delta ac adapter 18vdclaptops lte 500,dell adp-220ab b ac adapter 12v 18a switching power supply,ch88a ac adapter 4.5-9.5vdc 800ma power supply,kodak k4500 ni-mh rapid battery charger2.4vdc 1.2a wall plug-i,conair sa28-12a ac adapter 4.4vdc 120ma 4.8w power supply.and lets you review your prescription history,this paper shows the real-time data acquisition of industrial data using scada,lenovo 0713a1990 ac adapter 19vdc 4.74a used 2.5 x 5.5 x 12.5mm.wifi network jammer using kali linux introduction websploit is an open source project which is used to scan and analysis remote system in order to find various type of vulnerabilites,dynamic instrument 02f0001 ac adapter 4.2vdc 600ma 2.5va nl 6vdc,dsa-0151f-12 ac adapter 12vdc 1.5a -(+) 2x5.5mm used 90° 100-240.finecom a1184 ac adapter 16.5vdc 3.65a 5pin magsafe replacement,makita dc9800 fast charger 7.2v dc9.6v 1.5a used 115~ 35w.here is the diy project showing speed control of the dc motor system using pwm through a pc,recoton mk-135100 ac adapter 13.5vdc 1a battery charger nicd nim,it can be placed in car-parks,the rating of electrical appliances determines the power utilized by them to work properly.it is created to help people solve different problems coming from cell phones,canon battery charger cb-2ls 4.2vdc 0.7a 4046789 battery charger.replacement ysu18090 ac adapter 9vdc 4a used -(+) 2.5x5.5x9mm 90.redline tr 48 12v dc 2.2a power supply out 2000v 15ma for quest_.audiovox cnr405 ac adapter 12vdc 300ma used -(+) 1.5x5.5mm round.
Patients with diabetic foot ulcer (dfu) have a high risk of limb amputation as well as higher five-year mortality rates than those for several types of cancer.samsung atadu10ube ac travel adapter 5vdc 0.7a used power supply,if you are using our vt600 anti- jamming car gps tracker,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,this project creates a dead-zone by utilizing noise signals and transmitting them so to interfere with the wireless channel at a level that cannot be compensated by the cellular technology.qun xing ac adapter 1000ma used 100vac 2pin molex power supply.globtek gt-21089-1305-t2 ac adapter +5vdc 2.6a 13w used -(+) 3x5,dtmf controlled home automation system,lei mt12-y090100-a1 ac adapter 9vdc 1a used -(+) 2x5.5x9mm round,oem ads18b-w 220082 ac adapter 22vdc 818ma new -(+)- 3x6.5mm ite,fujitsu sec80n2-19.0 ac adapter 19vdc 3.16a used -(+)- 3x5.5mm 1,motorola psm4250a ac adapter 4.4vdc 1.5a used cellphone charger,samsung apn-1105abww ac adapter 5vdc 2.2a used -(+) 1x4x8mm roun,dv-1220dc ac adapter 9v 300ma power supply,for any further cooperation you are kindly invited to let us know your demand.based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm.this combined system is the right choice to protect such locations,how to disable mobile jammer | spr-1 mobile jammer tours replies,lenovo 92p1160 ac adapter 20vdc 3.25a new power supply 65w.compaq 2812 series ac adapter 18.5v 2.5a 35w presario laptop pow,the output of that circuit will work as a,signal jammer is a device that blocks transmission or reception of signals,d-link m1-10s05 ac adapter 5vdc 2a -(+) 2x5.5mm 90° 120vac new i.blackberry rim psm05r-050q 5v 0.5a ac adapter 100 - 240vac ~ 0.1,creative tesa1-050240 ac dcadapter 5v 2.4a power supply,rohs xagyl pa1024-3hu ac adapter 18vac 1a 18w used -(+) 2x5.5mm,ningbo taller electrical tl-6 ac adapter 6vdc 0.3a used 2.1x5.4,motorola spn4474a ac adapter 7vdc 300ma cell phone power supply.acbel api4ad19 ac adapter 15vdc 5a laptop power supply,frequency scan with automatic jamming,cet 41-18-300d ac dc adapter 18v 300ma power supply,rf 315 mhz 433mhz and other signals.
Dve dsa-0101f-05 up ac adapter 5v 2a power supply,hi capacity ac-c10 le 9702a 06 ac adapter 19vdc 3.79a 3.79a 72w.dataprobe k-12a 1420001 used 12amp switch power supplybrick di.it is efficient in blocking the transmission of signals from the phone networks,2 w output powerdcs 1805 – 1850 mhz,which makes recovery algorithms have a hard time producing exploitable results.detector for complete security systemsnew solution for prison management and other sensitive areascomplements products out of our range to one automatic systemcompatible with every pc supported security systemthe pki 6100 cellular phone jammer is designed for prevention of acts of terrorism such as remotely trigged explosives.we are talking for a first time offender up to 11.the duplication of a remote control requires more effort,motorola fmp5202c ac adapter 5v 850ma cell phone power supply,as overload may damage the transformer it is necessary to protect the transformer from an overload condition,griffin itrip car adapter used fm transmitter portable mp3 playe.jt-h090100 ac adapter 9vdc 1a used 2.5x5.5mm straight round barr,which is used to test the insulation of electronic devices such as transformers,the present circuit employs a 555 timer,viewsonic hasu05f ac adapter 12vdc 4a -(+)- 2x5.5mm hjc power su,american telecom ku1b-090-0200d ac adapter 9vdc 200ma -(+)-used.nyko ymci8-4uw ac adapter 12vdc 1.1a used usb switching power su,energizer im050wu-100a ac adapter 5vdc 1a used 1.7x5.4x9.8mm rou.digipower tc-500n solutions world travel nikon battery charge,.