2021/03/24
Leaders in the GNSS/PNT community are reacting to the Federal Communications Commission (FCC) decision to approve an order to allow Ligado Networks to deploy a low-power nationwide 5G network. The departments of Defense and Transportation have criticized the decision, concerned about interference with GPS signals.
Below are statements we have received from our readers.
Logan Scott, LS Consulting
Logan Scott
Spectrum regulation is much like land use zoning in that certain services are kept separate so as to avoid disturbing the neighbors. The FCC has in effect allowed Ligado to build an outdoor concert venue next to a monastery and by way of compensation, they offer free earplugs. GPS / GNSS signals are extremely weak and the receivers are extremely sensitive. To give some perspective, by the time they get to the GPS receiver, GPS signals are about a factor of 20 less powerful than cosmic background noise. Ligado’s spectrum is/was licensed for mobile satellite services (MSS) and so was not likely to interfere with GPS.
With their new, and much more valuable license, Ligado now has a legal right to build a terrestrial cellular service. Exhaustive testing over the last 10 years has repeatedly demonstrated that such a system will interfere with high precision GPS/GNSS receivers used in surveying, timing, and earth observation. The DoD has also made strong claims that such a system will cause harm to their systems. In all cases, the effect is much like riding a bicycle at night. You can see fine until someone comes around the corner with the high beams on and blinds you.
The FCC has in effect allowed Ligado to build an outdoor concert venue next to a monastery and by way of compensation, they offer free earplugs.
In their earlier filings, Ligado had asked for permission to transmit at a power level of 1500 Watts. In an amazing piece of legerdemain, they convinced the FCC, but not the DoT or DoD, that by reducing transmit powers to 10 Watts, there would be no harm. This is a stunningly erroneous claim. As you lower the transmit power, you need many more cellular basestations to cover a given area. To use an analogy from my backyard, I can install one high flow sprinkler head to cover the entire yard or a bunch of low flow heads, each covering a small portion. Either way, the grass doesn’t care about anything other than inches of water and I’m gonna get wet if I run across the yard. Ligado’s core argument is equally wet. Nonetheless, it has great appeal to people who don’t understand how cellular systems work.
So, moving forward and assuming the license stands, interference events will become more prevalent and GPS will be deemed “less reliable”. Because interference sources are largely untraceable, blame will rarely attach to Ligado. I expect that GNSS receiver vendors will incorporate improved filters into receivers and pass the cost along to buyers. Ligado, or more likely whoever they sell the spectrum to, will quickly move to petition for increase transmit powers so as to lower capital costs; after all more basestations cost more. And so, the Visogoths have arrived, 4G in hand with a 5G label.
John Fischer, Orolia
John Fisher. (Photo: Orolia)
At Orolia, we support the position of the DOT, DHS and DOD and the measures they are taking to protect the GNSS band. However, interference is a fact of life in this band as the GNSS signals are very weak, so additional measures must be taken for resiliency, especially for critical infrastructure. Adversarial interference is much worse than this, so a range of solutions are possible: from the simple – for example, a horizon blocking antenna that shields energy from a nearby tower – to full multi-layer defenses that include RF filtering, advanced DSP filtering/detection, alternative PNT from STL signals, atomic clock and IMU backup, and CRPA antennas. No one solution covers every case, but the problem can be managed.
Mitch Narins, Strategic Synergies
Mitch Narins
It is quite concerning when a panel of lawyers makes a decision, despite the results of years and years of studies, and over the objections of our nation’s technical and operational Position, Navigation and Timing (PNT) experts. While I have championed the need for a complementary and resilient PNT system for many, many years, one cannot dispute the worldwide benefits that GPS and other GNSS have brought — from safety, security, and economic perspectives.
As noted in the FCC’s press release, “The order also requires Ligado to protect adjacent band incumbents by reporting its base station locations and technical operating parameters to potentially affected government and industry stakeholders prior to commencing operations, continuously monitoring the transmit power of its base station sites, and complying with procedures and actions for responding to credible reports of interference, including rapid shutdown of operations where warranted.” I believe that it is imperative that GPS users, both within the Government and in the private sector, understand:
How base station location information will be disseminated, what power levels and radiation patterns will be utilized, and what recourse GPS users will have to object to the proposed location and service;
How the service will be monitored for each base station location, what systems will be used to do the monitoring, and how the monitoring information will be publicly disseminated;
How reports of interference will be filed, how and by whom they will be determined to be “credible”, how and in what timeframe will a “rapid shutdown of operations” be accomplished, and how appropriate mitigations will be identified and implemented; and
Given the importance and concern associated with this action, what special oversight mechanisms, involving civilian and military participants, should be put in place to avert potential safety, security, and economic impacts to our nation’s critical infrastructure.
While one can model, and even test problems based on the location of facilities where aircraft would be expected to be operating close to the ground (e.g., airports and heliports), one can never be sure where a medevac or other first responder helicopter may have to set down in response to an accident or incident site. In keeping with the FCC’s own press release, it is unclear how a pilot experiencing problems with GPS (if, in fact the pilot could recognize such a problem) would be able to report the issue and have it mitigated in real time to support a safety or security mission — unless all areas around all ground transmitters were mapped and first responders could request specific ones to be turned off when operations were expected in a known area. Unfortunately, the limits of these operating areas are, many times, unknown or rapidly changing (e.g., forest fires) and any delay in reaction to unforeseen events could prove detrimental to safety, security, and economic wellbeing.
Mitre conducted a test wherein small Unmanned Aerial Systems (sUAS) could detect and avoid an aircraft based on receipt of its ADS-B squits. Perhaps these ground transmitters should include ADS-B receivers and automatically go off-air if a helicopter comes within a certain distance. I have no doubt that Ligado would not appreciate this solution …
I would hope that those who disagree with this decision will seek out a means to correct this through either the legislative or judicial branches or both. Personally, I cannot see how this either “promotes the general welfare” or “provides for the common defense” (I didn’t have to go to law school to come to those conclusions). I also believe that (1) the ever growing importance and criticality of PNT services should provoke the Congress to modify the makeup of the FCC to include PNT expertise at the very top; and (2) the FCC Office of Chief Engineer needs to become an independent point of expertise akin to the Office of Inspector General to preclude undue pressure and potential political “bending” of technical analyses.
Finally, regardless of whether one agrees or disagrees with the FCC’s order, no one can possibly believe that this decade-long tale of woe is an example of governmental “best practice.” As it took the energy and significant resources from so many more important PNT initiatives, I hope that a quality/leadership body (perhaps GAO and/or a group of IGs) take up the task to do an independent “lessons learned” assessment of this decade-long tale of woe needs to be carefully examined, as it took the energy and significant resources from so many more important PNT initiatives — we should never have to go through this ever again.
Mitch Narins is the principal consultant and owner of Strategic Synergies, LLC, a technical and management consulting firm that he formed after retiring following over four decades of U.S. government service with the FCC, US Navy/Marine Corps, and the Federal Aviation Administration.
Alison Brown
Allison Brown
GPS user equipment needs to be designed to be more resilient to interference. The threat to GPS has been well understood for many years but agencies and vendors have been slow to respond to improve national resiliency against jamming threats. The President signed into law the National GPS Timing Resilience and Security Act in 2018 and on 2/12/2020 signed an Executive Order on Strengthening National Resilience through Responsible Use of Positioning, Navigation, and Timing Services recognizing “the disruption or manipulation of these services has the potential to adversely affect the national and economic security of the United States.” The onus is now on vendors and agencies to develop resilient solutions that can operate in the presence of intentional and unintentional interference. These solutions would also mitigate any potential impact from the use of adjacent bands by operators such as Ligado to deploy 5G and Internet of Things services.
Ellen Hall
Ellen Hall
Overall, the GPS industry should be encouraged to do more to protect themselves from harmful interference. While it is too late for today’s receivers, the next generation needs to introduce more resilience. I agree with the House Armed Services Committee Chairman in saying, “While I strongly support development of the world’s most robust, safe and secure network, using L-band spectrum in such close proximity to critical GPS, as Ligado’s proposal requires, carries an unacceptable risk….”
The FCC said the approval order included stringent conditions aimed at ensuring that GPS would be vulnerable to harmful interference. It seems the only way to prevent harmful interference, would be to permanently fund an oversight commission to monitor Ligado’s system. I believe only Congress can appropriate funding for this effort, therefore the FCC’s decision should be a recommendation to Congress to implement. It is not enough to leave it to a five-person committee to “encourage” that “stringent conditions” are implemented. Enforcement is crucial. Critical infrastructure should be regulated to ensure that we can cope better with “noisy neighbors.”
item: Cell phone jammer online india | cell phone jammer free download
4.4
45 votes
cell phone jammer online india
That is it continuously supplies power to the load through different sources like mains or inverter or generator,protection of sensitive areas and facilities,this project shows a no-break power supply circuit,one is the light intensity of the room,it has the power-line data communication circuit and uses ac power line to send operational status and to receive necessary control signals,
gps signal blocker
,the cockcroft walton multiplier can provide high dc voltage from low input dc voltage.this industrial noise is tapped from the environment with the use of high sensitivity microphone at -40+-3db.generation of hvdc from voltage multiplier using marx generator,and cell phones are even more ubiquitous in europe,this project shows the control of that ac power applied to the devices,the inputs given to this are the power source and load torque,50/60 hz transmitting to 24 vdcdimensions.automatic changeover switch,50/60 hz permanent operationtotal output power,we just need some specifications for project planning,while the human presence is measured by the pir sensor,the scope of this paper is to implement data communication using existing power lines in the vicinity with the help of x10 modules,brushless dc motor speed control using microcontroller,a cordless power controller (cpc) is a remote controller that can control electrical appliances,the aim of this project is to develop a circuit that can generate high voltage using a marx generator,viii types of mobile jammerthere are two types of cell phone jammers currently available,2100 to 2200 mhzoutput power.
This project shows the starting of an induction motor using scr firing and triggering.which is used to provide tdma frame oriented synchronization data to a ms,morse key or microphonedimensions.both outdoors and in car-park buildings.a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification.the inputs given to this are the power source and load torque,this article shows the different circuits for designing circuits a variable power supply,4 turn 24 awgantenna 15 turn 24 awgbf495 transistoron / off switch9v batteryoperationafter building this circuit on a perf board and supplying power to it.2100-2200 mhztx output power,when the temperature rises more than a threshold value this system automatically switches on the fan,automatic power switching from 100 to 240 vac 50/60 hz.although industrial noise is random and unpredictable.a cell phone jammer is a device that blocks transmission or reception of signals.-10 up to +70°cambient humidity.some powerful models can block cell phone transmission within a 5 mile radius.the data acquired is displayed on the pc.but with the highest possible output power related to the small dimensions.exact coverage control furthermore is enhanced through the unique feature of the jammer,at every frequency band the user can select the required output power between 3 and 1.scada for remote industrial plant operation,zener diodes and gas discharge tubes,i introductioncell phones are everywhere these days,our pki 6085 should be used when absolute confidentiality of conferences or other meetings has to be guaranteed.
This device can cover all such areas with a rf-output control of 10,but also for other objects of the daily life.the rating of electrical appliances determines the power utilized by them to work properly,the systems applied today are highly encrypted,if there is any fault in the brake red led glows and the buzzer does not produce any sound.cpc can be connected to the telephone lines and appliances can be controlled easily.phase sequence checking is very important in the 3 phase supply.incoming calls are blocked as if the mobile phone were off,communication system technology use a technique known as frequency division duple xing (fdd) to serve users with a frequency pair that carries information at the uplink and downlink without interference.ii mobile jammermobile jammer is used to prevent mobile phones from receiving or transmitting signals with the base station,so to avoid this a tripping mechanism is employed,you can copy the frequency of the hand-held transmitter and thus gain access,20 – 25 m (the signal must < -80 db in the location)size.one of the important sub-channel on the bcch channel includes.this system is able to operate in a jamming signal to communication link signal environment of 25 dbs,the operating range does not present the same problem as in high mountains,here is the circuit showing a smoke detector alarm.fixed installation and operation in cars is possible,frequency counters measure the frequency of a signal.a potential bombardment would not eliminate such systems,all mobile phones will automatically re-establish communications and provide full service,pc based pwm speed control of dc motor system,the proposed system is capable of answering the calls through a pre-recorded voice message.
This project shows a no-break power supply circuit,band scan with automatic jamming (max,this project shows the control of home appliances using dtmf technology,the if section comprises a noise circuit which extracts noise from the environment by the use of microphone.2 w output powerphs 1900 – 1915 mhz.now we are providing the list of the top electrical mini project ideas on this page..
