Добрый вечер. Есть ли возможность получить компетентный ответ (хотя бы в общем) от специалиста в области РЭБ? Собственно интересует, возможно ли на нынешнем этапе эффективное подавление военных GPS приемников? С одной стороны подобные разработки есть и рекламируются, но "спецы" работающие с GPS говорят, что заявленные для таких систем дальность подавления в 100-150 км реальны только для гражданских изделий и для военных приемников эти значения будут составлять не более 150-200 метров. То есть, по факту, против ВТО с системами спутниковой коррекцией не эффективны.
Free space loss FSL = 32.45 + 20Log10(F in MHZ) + 20log10(D in Kms)
dlja GPS 1500 mgz i 20 000 km = 182 db
The spot beam is ~20 dB more powerful than the whole Earth coverage beam M-code signal at Earth's surface: –158 dBW for whole Earth antenna, –138 dBW for spot beam antennas. *************************************************************************************** ili -108 dbm s 2013 goda http://en.wikipedia.org/wiki/GPS_modernization<\/u><\/a>
Отправлено: 11.12.10 23:58. Заголовок: The payload consists..
The payload consists of L-Band navigation signals in 25 channels separated by 0.5625 MHz intervals in 2 frequency bands: 1602.5625 - 1615.5 MHz and 1240 - 1260 MHz.
EIRP 25 to 27 dBW *******************
na 2 db xuze chem y GPS poslednego bloka ,podnjat ne problema no bez naprawlennix antenn ...
Powischenie nesuschej w naprawlenii 20ghz/44 ghz Milstar/AEHF i ostronapr. antenni (budut isp w GPS s 2013 goda i na 1.5 ghz) - bolschaja ystojchiwost k postanowke pomex (smotri wische st. IRE RAN)
Ewropejskaja tochka zrenija o wozmoznosti ispolzowanija C-Band /5.4 5.9 ghz/
Отправлено: 12.12.10 00:18. Заголовок: Session A5, Paper #1..
Session A5, Paper #1
Simulation Study of UWB-OFDM SAR for Navigation Using a Kalman Filter K. Kauffman, J. Raquet, Air Force Institute of Technology; Y. Morton, D. Garmatyuk, Miami University
Alternatives to GPS are necessary for robust navigation solutions. In environments such as urban canyons, indoor applications, or areas with active jamming, non-GPS based position and velocity sensors must be used to obtain or aid navigation solutions. There are a number of sensors that have been used for navigation, however in many situations these sensors do not operate well. The addition of alternative sensors allows the navigation platform to operate under more diverse environmental conditions.
In our previous work, we developed an ultra-wide-band (UWB) orthogonal frequency division multiplexed (OFDM) radar system prototype [1] with 500MHz baseband bandwidth. -------------------------------------------------------------------------- The UWB-OFDM sensor exhibits many useful properties for navigation. Like other UWB systems, it has high resolution target ranging and localization when used as a synthetic aperture radar (SAR) [2]. The OFDM waveform has good potential for anti-jamming and multipath mitigation [3][4]. Using an active UWB-OFDM sensor allows for even greater anti-jamming capabilities over other sensors using RF signals of opportunity ----------------------------------------------------------------------------------------
. Since our prototype is software defined, the OFDM symbol is changeable on a pulse-to-pulse basis. This allows the spectrum of the signal to be modified in real time to avoid narrow-band interference, such as GPS. One obstacle in using UWB-OFDM for navigation is the high computational requirements for constructing SAR images in real-time. Our previous study developed an efficient algorithm for computing partial SAR images rapidly for real-time high resolution positioning of a small number of targets [5].
Recently, we developed and simulated a two-dimensional dead-reckoning navigation system based on an active, on-board UWB-OFDM sensor [6]. This initial work assumes that a single aerial vehicle (AV) moves along a fixed axis recording raw SAR data in a stripmap configuration, with random persistent scatterers located along the axis of travel. A sparse target SAR algorithm [5] was combined with a two-stage tracking and estimation algorithm to obtain both the AV and target positions in real time. In the first stage, the initial known positions of the AV and the AV-target range measurements obtained by the UWB-OFDM sensor are used to estimate targets locations. In the second stage, the newly estimated target positions are combined with existing and new range measurements to infer AV positions. Through this preliminary investigation, we demonstrated the feasibility of using the UWB-OFDM sensor as a navigation aid, under various ideal assumptions.
In this paper, we extend our previous work by making several drastic improvements. First, the two-stage estimation and tracking algorithm is replaced with a Kalman filter based approach. Second, an inertial navigation sensor is incorporated into the simulation. Third, more realistic models are used to replace some of the ideal assumptions used in previous study:
1. The persistent scatterers are replaced by conductive spheres modeled using Lorenz-Mie theory [7] to account for frequency-dependent distortion of the UWB waveform. 2. Swerling target models [8] are used to account for time-varying stochastic properties of the targetґs radar cross section. 3. The channel is modeled using realistic signal propagation path loss instead of a white Gaussian noise channel.
The paper presents the detailed implementation of new Kalman filter based estimation and tracking algorithm and analyzes the effects of the frequency and time dependent distortion in the measurement data due to the more realistic target and channel models. The estimated AV position is compared to the actual simulated flight distance. The position drift is calculated for varying conditions, such as target availability, target and channel model parameters, and received SNR. Performance evaluations demonstrate the robustness of the Kalman filter based approach. Quantitative comparisons of solutions generated by the new implementation with our previous two-stage approach will also be discussed.
[1] D. Garmatyuk, K. Kauffman, J. Schuerger, and S. Spalding, "Wideband OFDM System for Radar and Communications," in Proceedings of 2009 IEEE Radar Conference, Pasadena, CA, 2009. [2] D. S. Garmatyuk, "Simulated imaging performance of UWB SAR based on OFDM," in Proc. 2006 IEEE Int. Conf. on Ultra-Wideband, Waltham, MA, 2006, pp. 237-242. [3] J. Schuerger and D. Garmatyuk, "Deception jamming modeling in radar sensor networks," in Proc. 2008 Military Communications Conference (MILCOM), San Diego, CA, Nov. 2008. [4] C. Schexnayder, J. Raquet, and R. Martin, "Effects of Oversampling and Multipath on Navigation Using OFDM Signals of Opportunity," Proceedings of ION GNSS-2008, Savannah, GA, Sep 2008. [5] K. Kauffman, "Fast target tracking technique for synthetic aperture radars," M.S. thesis, Miami University, Oxford, OH, USA, 2009. [6] K. Kauffman, Y. Morton, J. Raquet, D. Garmatyuk, "Simulation study of UWB-OFDM SAR for dead-reckoning navigation," Proc. ION ITM, San Diego, CA, Jan. 2010. [7] A. Stratton: Electromagnetic Theory, New York: McGraw-Hill, 1941. [8] Skolnik, M. Introduction to Radar Systems: Third Edition. McGraw-Hill, New York, 2001.
Отправлено: 12.12.10 20:42. Заголовок: The minimum value of..
The minimum value of 20 dB J/S was chosen because C/A acquisition at 24 dB J/S is a common military requirement. ************************************* The maximum value was chosen because no GPS receivers can track at 80 dB J/S against a WB jammer without employing beamsteering,*nulling, or some other multielement antenna technique. ****************
Отправлено: 12.12.10 21:26. Заголовок: primer razrabotka wo..
primer razrabotka woenngo GPS priemnika (sponsori Air Force i US Navy) s J/S -120 sb
RF Applications
Two RF applications are under development - a high linearity, high dynamic range RF receiver, targeting GPS receivers and a clock synchronization chipset, targeting backplane applications.
High Linearity, High Dynamic Range RF Receivers: A monolithic chip is under development to enable operation of GPS receivers in the presence of jamming sources. This technology is very enabling in the context of hand-held applications and GPS guided munitions, in which a compact design is of the essence.
The NTK-Ironman-01 is a complete dual-channel global positioning system (GPS) front-end down converter. This low power CMOS IC integrates a low-noise amplifier (LNA), image rejection mixer, automatic-gain-control amplifier (AGC), secondary mixer, and clock buffer. External IF, baseband filters, and ADCs enhance flexibility. The device supports C/A, P(Y), and M codes.
This device provides the most versatile integrated front-end available. Two independent down converters per channel (shown below) gives it a wide range of supported frequency plans. Each mixer utilizes an independent external COTS synthesizer to generate the local oscillator (LO). Further, each down converter can be used for high side or low side mixing and operate on L1 and L2 simultaneously. Alternatively, both down converters can operate only on L1, L2 or L5, as is necessary when used with an adaptive antenna array.
The digital AGC allows the receiver to accommodate multiple wideband and narrow band jammers having a total power up to -13 dBm without clipping.
The device supports multichannel digital adaptive anti-jam signal processors providing wideband cancellation in excess of 50 dB. When combined with a GPS signal processor providing 70 dB A/J the RF ASIC will support GPS tracking with 120 dB J/S.
Related Stories: Americas - USA, Contracts - Modifications, Electronics - General, GPS Infrastructure, Other Corporation
DAGR GPS Receiver (click to view full)Rockwell Collins in Cedar Rapids, IA received a $20.2 million contract modification to provide 81,622 DAGR hand-held GPS receivers and accessories to the US Air Force GPS Wing (GPSW/PK) in El Segundo, CA.
This contract modification is part of a $450 million DAGR follow-on contract (FA8807-09-C-0002) announced March 18/09 by Rockwell Collins. The company received its first order from the USAF under the contract that same month: 53,920 DAGR receivers and accessories for $87.5 million.
The DAGR is a handheld GPS receiver that provides position, navigation and situational awareness for US troops.
The receiver provides precise timing to synchronize tactical radios, missile platforms and other situational awareness navigation systems and includes a Graphical User Interface (GUI) that provides ease of use.
The DAGR design incorporates anti-jam improvements and denied GPS capabilities for worldwide enhanced battlefield protection. It is the first US handheld GPS receiver program to include the Selective Availability Anti-Spoofing Module (SAASM) security device. The Rockwell Collins SAASM includes:
NightHawk 12-channel GPS signal processor Navigation using up to 12 GPS satellites Advanced correlator engine for accelerated Direct-Y code and C/A code acquisitions Security architecture using a Key Data Processor (KDP-II) Unclassified-when-keyed operation and updated security features The DAGR’s dual frequency RF front end allows continuous track of both the L1/L2 GPS satellite frequencies. A precision time source runs continuously to allow rapid acquisition of the GPS satellites when the receiver is turned on.
Отправлено: 16.12.10 18:31. Заголовок: The nominal minimum ..
The nominal minimum GPS receiver base bandwidth of 50 Hz has been used for purposes of calculating noise and jamming interference power levels so far in this series. This approach was initially adopted for conceptual simplicity. But by this point, the reader is aware that different GPS functions employ varying bandwidth processes. ################################################ Sometimes even the same function employs variable adaptive bandwidth filtering techniques, as in the case of the carrier/code tracking loops. To avoid the necessity of computing separate interference levels for the multiple bandwidths employed in GPS receivers, it is common to reference such computations to a 1 Hz bandwidth #########################
Lans -Добрый вечер. Есть ли возможность получить компетентный ответ (хотя бы в общем) от специалиста в области РЭБ? Собственно интересует, возможно ли на нынешнем этапе эффективное подавление военных GPS приемников? С одной стороны подобные разработки есть и рекламируются, но "спецы" работающие с GPS говорят, что заявленные для таких систем дальность подавления в 100-150 км реальны только для гражданских изделий и для военных приемников эти значения будут составлять не более 150-200 метров. То есть, по факту, против ВТО с системами спутниковой коррекцией не эффективны #############################################
srawnite 4 sluschaja w stat'e nize . Wo wsex sluschajx moschnost YM post. pomex 10 watt ( Rossisjkie w Irake -4 watta)
posmotrite kak powischaetsja j/S i snizaetsja radius dejstwija za schet suzenija polosi s 20 herz do 2 herz pri tracking ( 10 db) za schet adaptive atenna patern (+26 db) i kombinazii
priwedena dalnost kak dlja aquisition tak i tracking dlja wsex sluchaew -----------------------------------------------------------------------------------
by Wm. Robert Johnston last updated 28 January 2009
Effects of high-altitude nuclear explosions, summary:
The familiar immediate effects of low-altitude nuclear explosions are flash, blast, and prompt radiation. Effects are significantly different for explosions above most of the atmosphere. Since blast is the shock wave transmitted through air, this is attenuated with height and is absent for explosions beyond the atmosphere. Flash is the visible and infrared light pulse from the fireball formed from heated air. With higher altitude, the fireball formation is significantly altered with consequent effects on flash. Prompt radiation includes ionizing radiation from the nuclear reactions in the warhead and decay of fission products left by the explosion. These radiations, particularly neutron radiation, are significantly attenuated by the atmosphere for low altitude bursts. For explosions above most of the atmosphere, ranges of prompt radiation effects are greater than for atmospheric bursts.
Several effects are relatively unique to high altitude bursts:
* Electromagnetic pulse (EMP) is important only for high altitude bursts. For such detonations, ionization of the upper atmosphere can produce a brief intense pulse of radio frequency radiation which can damage or disrupt electronic devices. For explosions above most of the atmosphere, EMP can affect large areas. * Ionization of the atmosphere from explosions in the atmosphere can interfere with radar and radio communications for short periods. * Charged particles produced by explosions above the Earth's atmosphere can be captured by the Earth's magnetic field, temporarily creating artificial radiation belts that can damage spacecraft and injure astronauts/cosmonauts in orbit.
0800067 - High-Altitude Nuclear Weapon Effects Part Two - Systems Interference - 1963 - 16:29 - Color - Through past nuclear testing, the Department of Defense and the Atomic Energy Commission determined that a nuclear weapon exploded at high altitude with a sufficient yield would cause adverse effects on communication and radar devices.
This technically oriented video, which uses many animated audio-visual aids to explain scientific points of interest and explores the weapons effects on military systems. The first portion deals with a hypothetical reentry vehicle armed with a nuclear warhead. The video explains how three different nuclear detonations might be required to track and destroy the incoming vehicle. The next portion explains how a nuclear explosion would more adversely affect the low-power downlink of radio transmissions to aircraft or satellites than the more powerful uplink. Other atmospheric chemistry and infrared systems problems are discussed in the video. [BR]http://www.youtube.com/watch?v=T6eLPLR_WPs
0800066 - High-Altitude Nuclear Weapon Effects Part One - Phenomenology - 1963 - 20:53 - Color - When nuclear weapons are detonated at high altitudes, they cause dramatic changes in the atmosphere and ionosphere. In a very technical presentation, this video discusses such things as the interactions of electrons and positive ions and shows the electromagnetic regions and how they carry electrical charges from one hemisphere to another. The video also discusses how there is much information unknown about nuclear explosions at extremely high altitudes, especially above 250 kilometers, where there is less atmospheric resistance.
Отправлено: 25.04.11 21:41. Заголовок: he Magnavox MX-8000 ..
he Magnavox MX-8000 Anti-jam GPS Receiver (AGR) was specifically designed for operation in heavily jammed environments, and was to be used in the cancelled Northrop AGM-137 TSSAM missile. This receiver uses adaptive nulling techniques to suppress jammers, and beam steering to boost the satellite signal. The receiver will acquire a GPS signal with a 70 dB Jam/Signal ratio (jam power 10,000,000 times higher than GPS signal) and once acquired, track a GPS signal with a 100 dB Jam/Signal ratio (jam power 10,000,000,000 times higher than GPS signal). ######################################################################
Nowaja razrabotka do 120 db J/S ,no klipping w rajone 0 dbm ili xuze 0 dbm na 50ohm eto .224 volta
Dla srawnenija elektrostat. ysilitel priemnika S-300v rabotaet pri 150 voltax na wxode
ARU mozet oslabit 150 volt pomexi na wxode GPS priemnika do 0.1 volta ili mensche ,no ############################################################ poleznij signal toze budet oslablen #########################
Prinimat odnowremmeno slabij signal GPS i ochen silnij pomexi GPS priemnik ne mozet
elektrostat . ysilitel ot S-300 V mozet / dlja atomnoj wojni/ It is worth comparing the complexity of this receiver with the simplicity of commercial receivers, which are highly susceptible to interference and hostile jamming (Hughes-Magnavox). http://www.ausairpower.net/TE-GPS-Guided-Weps.html
Отправлено: 30.04.11 12:13. Заголовок: 9S32 RLS The low n..
9S32 RLS
The low noise receiver (noise factor 3 dB) uses an electrostatic amplifier tube that can withstand leakage powers of several hundred Watts without damage and with near-instantaneous recovery to full gain and sensitivity when the transmitted pulse ends. *****************************************************************************
7volt na 50 omnuju antennu eto 1 watt na wxode priemnika 70 volt eto 100 watt [BR]http://www.ausairpower.net/APA-Russian-SAM-Radars-DKB.html#mozTocId551440 Thus, the loss attributed to solid-state protective devices commonly required in Western radars is also absent.
Dlja sravnenija s priemnikom S-300V ,kotorij rabotaet ,kogda na wxode bolee 100 volt - ##########################################################################
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