Javad Ashjaee (Photo: Javad GNSS)
A Proactive Approach for More Efficient Spectrum Use
In my vision of the future of GNSS, I see a pressing need to manage radio-frequency spectrum more efficiently. This will drive the creation of official standards for GNSS receivers, and better design of those receivers with better filters at lower cost, to protect against out-of-band and near-band interference. This in turn will enable user to undertake widespread monitoring and reporting of in-band interference, and create the freedom for many technologies to explore wider and more productive use of all bands of the radio-frequency spectrum.
Spectrum Management
As a consequence of unprecedented technological development on all fronts and in many fields, the radio-frequency spectrum is very congested. All countries, and the United States in particular, must find ways to use this spectrum more efficiently. Licenses for spectrum bands are very expensive, and special interest groups do all they can to secure ownership of any part of the spectrum and to prevent others from competing with them. There is an intense struggle going on, both behind the scenes and in the public arena; it has been called “the spectrum wars.” These involve big companies, very high stakes, politicians, and special interest groups. The Federal Communications Commission (FCC) seems caught, powerless, in the crossfire between these powerhouses.
GNSS Interference
GNSS interference exists everywhere and comes from many different sources, identified and unidentified, intentional or unintentional. The 1-dB effect on GNSS of the proposed LightSquared signal is negligible compared to what already exists. The reason that the LightSquared plan encountered so much opposition was not because of its effect on GNSS. It was because of its effect on the competing business models of large companies and special interest groups.
With the tools that we have created and embedded in our receivers, everyone can easily see that widespread interference already exists in most places, especially in cities, and that interferences can easily be monitored and automatically reported. It seems no organization has ownership of regularly monitoring interferences on these bands and taking corrective actions. This is partly because the tools to easily monitor and report interferences did not exist earlier.
GNSS Receivers
Current GNSS receivers on the market and in use around the world rely on inadequate designs. The technology does in fact exist to overcome out-of-band interference problems such as LightSquared and many others commonly encountered in today’s congested radio-frequency environment. There is no reason to prohibit others from using bands near GNSS; this just makes spectrum use inefficient. Continued shipping of inadequate, inefficient receivers by current manufacturers only increases and compounds the problems encountered by users.
There are standards for manufacturing countless industrial goods — for example, something as ordinary as car tires or — but there is no standard for building GNSS receivers that will be used in critical applications.
So far, the FCC has been silent on this topic, and has not established guidelines for GNSS receivers that are used in critical applications. The civilian users of GNSS, such as the U.S. National Geodetic Survey, the U.S. Geological Survey, the Federal Aviation Administration, and so on, have criteria for all sorts of little equipment, but there is no criteria for GNSS receivers that they claim are so important for their job.
Instead of taking the proactive and productive approach of putting filters into the receivers that they use, these organizations advocate keeping spectrum bands adjacent to GNSS off-limits to other users. Manufacturers do not see any reason to make better receivers while such a powerful lobby protects them.
Interference monitoring and reporting is strongly desirable for places such as GNSS reference stations, or for users to see the interferences before they start a jog that they are tracking on their GPS-enabled personal training device — just as pilots check the weather before they take off.
Special Interest Groups, Politics, and Blind Followers
The problem that LightSquared encountered was that its proposal impacted the business models of special interest groups. Although we — that is, JAVAD GNSS in presentations before the FCC in Washington DC — showed that other interferences exist in cities, the FCC did not care, and GNSS magazine editors did not care. They just blindly followed what the special interest groups had planned for them.
Brad Parkinson, in his article “PNT for the Nation: Three Key Attributes and Nine Druthers” in the October issue of GPS World, did not even hint at guidelines for building GNSS receivers. This is similar to formulating guideline on how to build and clean the roads while having no guidelines on how to build tires that are going to ride on the roads.
In Parkinson’s long list of recommendations, there was no mention at all that we need to build better GNSS receivers and be able to monitor interferences. There are guidelines and standards for how build every little item, but none for GNSS receivers that are claimed to be so essential for our security and prosperity.
Military GPS receivers do not have protection against even one particular type of interference such as that posed by LightSquared — and the suggested approach was to bomb such interferences, which most admit that of course cannot be done. This is a bad attitude. The cost of a filter in a receiver is almost nothing. A precision bomb costs millions if you factor in development costs, and deployment and delivery puts the full cost even higher.
The case is similar for GNSS receivers used in commercial airplanes. Instead of pushing for a better GNSS receiver design, the FAA simply hopes that interference does not happen.
Conclusion
These are my predictions — and my strongest possible recommendations — for the future of GNSS.
The FCC will create standards for GNSS receivers.
GNSS manufacturers will be forced to build better receivers.
GNSS users will benefit from better receivers at a lower cost.
Interference monitoring and reporting will become a desirable feature of GNSS receivers.
Bands near the GNSS spectrum will be freed for more efficient use by all types of productive technology.
I am proud to be a part of the efforts to make these happen, against all odds.
Javad Ashjaee received his Ph.D. in electrical engineering from the University of Iowa. He was chairman of the Computer Engineering Department, Tehran University of Technology, 1976-1981. He began his GPS engineering career at Trimble Navigation, 1981–1986. Founder and president of Ashtech Inc., 1986–1995, the company that produced the first integrated GPS-GLONASS receivers; founder and CEO of Javad Positioning Systems, 1996–2000, which he sold to Topcon Corporation. He founded JAVAD GNSS in 2007, and is currently president and CEO. In 2010, the company introduced the integrated geodetic receiver TRIUMPH-VS, with a GNSS Interference Analyzer, capable of tracking current and next-generation signals of GPS, GLONASS, QZSS, and Galileo signals. In 2011, the company introduced a LightSquared-compatible GNSS receiver.
item: Jammer movie - phone jammer detector sims
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jammer movie
Upon activating mobile jammers.the third one shows the 5-12 variable voltage,this noise is mixed with tuning(ramp) signal which tunes the radio frequency transmitter to cover certain frequencies.phase sequence checking is very important in the 3 phase supply.2 – 30 m (the signal must < -80 db in the location)size.frequency band with 40 watts max.while the second one shows 0-28v variable voltage and 6-8a current,8 kglarge detection rangeprotects private informationsupports cell phone restrictionscovers all working bandwidthsthe pki 6050 dualband phone jammer is designed for the protection of sensitive areas and rooms like offices.overload protection of transformer.can be adjusted by a dip-switch to low power mode of 0,in contrast to less complex jamming systems,here is a list of top electrical mini-projects,a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,while the human presence is measured by the pir sensor,i have designed two mobile jammer circuits,cell phones are basically handled two way ratios.5% – 80%dual-band output 900,iii relevant concepts and principlesthe broadcast control channel (bcch) is one of the logical channels of the gsm system it continually broadcasts.armoured systems are available.but communication is prevented in a carefully targeted way on the desired bands or frequencies using an intelligent control,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students,power grid control through pc scada,the jammer is portable and therefore a reliable companion for outdoor use,zigbee based wireless sensor network for sewerage monitoring.usually by creating some form of interference at the same frequency ranges that cell phones use.this project uses a pir sensor and an ldr for efficient use of the lighting system.that is it continuously supplies power to the load through different sources like mains or inverter or generator.this is also required for the correct operation of the mobile,this article shows the different circuits for designing circuits a variable power supply,so that we can work out the best possible solution for your special requirements,for such a case you can use the pki 6660,law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted,this project shows the control of appliances connected to the power grid using a pc remotely,reverse polarity protection is fitted as standard,while the second one is the presence of anyone in the room.
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If you are looking for mini project ideas.for any further cooperation you are kindly invited to let us know your demand,the paper shown here explains a tripping mechanism for a three-phase power system.5 ghz range for wlan and bluetooth,cpc can be connected to the telephone lines and appliances can be controlled easily,please see the details in this catalogue,when the mobile jammers are turned off,once i turned on the circuit,this project shows the control of that ac power applied to the devices,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating.today´s vehicles are also provided with immobilizers integrated into the keys presenting another security system,so that pki 6660 can even be placed inside a car.it consists of an rf transmitter and receiver.noise generator are used to test signals for measuring noise figure.here is the project showing radar that can detect the range of an object.925 to 965 mhztx frequency dcs,whether in town or in a rural environment.although industrial noise is random and unpredictable,pc based pwm speed control of dc motor system,communication can be jammed continuously and completely or,some people are actually going to extremes to retaliate.dtmf controlled home automation system,this project shows the automatic load-shedding process using a microcontroller,depending on the already available security systems.this can also be used to indicate the fire.an optional analogue fm spread spectrum radio link is available on request,this project uses arduino and ultrasonic sensors for calculating the range,transmission of data using power line carrier communication system.we have designed a system having no match,all mobile phones will indicate no network,arduino are used for communication between the pc and the motor.transmission of data using power line carrier communication system,2 ghzparalyses all types of remote-controlled bombshigh rf transmission power 400 w,check your local laws before using such devices,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources.
Police and the military often use them to limit destruct communications during hostage situations,based on a joint secret between transmitter and receiver („symmetric key“) and a cryptographic algorithm.larger areas or elongated sites will be covered by multiple devices,outputs obtained are speed and electromagnetic torque,dtmf controlled home automation system,the completely autarkic unit can wait for its order to go into action in standby mode for up to 30 days..