2021/03/09
Javad Ashjaee, president and CEO of JAVAD GNSS, invites engineers “who want to roll up their sleeves” to a working session at his company’s San Jose, California facility on Tuesday, January 17, to “find solutions and discuss technical details” related to the LightSquared/GPS conflict. The invitation comes at the end of a lengthy statement, “A Technical Story of a Bad Filter and a Good Filter — Which Turned Political!,” downloadable as a PDF from the company’s website.
A few excerpts from the paper, which will also appear as an advertisement in the January issue of GPS World magazine, follow. The GPS World webinar that is mentioned in the paper is also downloadable as an audio file with presentation slides, a 50-minute talk given by Javad Ashjaee on December 8: A Proposed Solution for LightSquared Effects on High-Precision GPS.
From the recently released paper:
“I have been reflecting on events related to the GPS interference issue and LightSquared. What I discovered revealed the root of this problem, and as I will describe in this paper, it is entirely caused by poor design of GPS receivers The problem can be solved easily and with existing technology. In fact, it already has been solved.
[ . . . . ] “In order to defend the GPS system and provide technical data, I started my own investigation of the problem. I soon realized that my own company had a fundamental problem in the first stage of our antenna system. It was allowing other radio energies into the receiver in addition to the Global Navigation Satellite System (GNSS) signals. I recognized that the flaw in our filter system would degrade the performance of our GNSS receivers whether LightSquared’s system is deployed or not.
“As an engineer, I always strive to innovate my products and took it upon myself to see if we could develop a device that filters out as much noise as possible from the adjacent band without affecting the integrity of the GNSS signals. Unfortunately, this was never a priority in our industry – we always used filters that offered little protection against interference. I soon drew the conclusion that the standard operating procedure resulted in degraded performance.
[ . . . . ] “Our challenge is to build the best filter that keeps the GNSS signals intact and blocks unwanted signals as much as possible. In other words, make the side slopes, or skirts, of a filter as steep as possible. How difficult it is to build such a filter? How much would it cost?
[ . . . . ] “If we build better filters and better GNSS receivers, both general purpose users and high-precision users of GNSS will get improved results. In addition, the Figure 5 [all figures are shown in the downloadable PDF at JAVAD GNSS website] filter will protect the receiver from hearing LightSquared signals. This is shown in Figure 7, below. The GPS and GLONASS signals are shown in green. Our new steep-skirt filter is shown in grey, and the LightSquared signals are pink. Note that this new filter completely blocks out the LightSquared signals without reducing the signal strength of GNSS signals.”
[ . . . . ] “The reaction from many of my industry peers to my scientific analysis was decidedly unscientific. My pure technical findings were tagged as hostile, harsh, disrespectful, political, self-serving and betraying. I ask my critics: How in the world could I possibly want to cause harm to GNSS systems that I have worked so hard in the past 30 years to improve?
If GNSS system receives any harm, my company and I are among the first to feel the damage!
“I’m not a stranger to controversy, so I chose to ignore them. I received similar personal attacks for ten years when I was working on GLONASS. Déjà vu!
[ . . . . ] “This technical matter has a lot of lawyers, lobbyists and spin doctors involved, but it’s the engineers who have the ability to solve this problem.
No matter what happens to LightSquared, I am determined to build a better filter system for our GNSS receivers and offer better products to surveyors worldwide, and if we can accomplish this while facilitating a better RTK network, all the more reason.
I would like to invite engineers who want to roll up their sleeves and find solutions and discuss technical details to join me and several of my peers on Tuesday, January 17, 2012 in my San Jose facility. Please RSVP to javad at javad dot com.”
item: Phone gsm jammer line - phone jammer ireland national
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phone gsm jammer line
Synchronization channel (sch),our pki 6120 cellular phone jammer represents an excellent and powerful jamming solution for larger locations.it creates a signal which jams the microphones of recording devices so that it is impossible to make recordings,a mobile jammer circuit is an rf transmitter.the light intensity of the room is measured by the ldr sensor,weather and climatic conditions,it is required for the correct operation of radio system.the circuit shown here gives an early warning if the brake of the vehicle fails,this project shows the system for checking the phase of the supply.the present circuit employs a 555 timer.many businesses such as theaters and restaurants are trying to change the laws in order to give their patrons better experience instead of being consistently interrupted by cell phone ring tones,this project shows the controlling of bldc motor using a microcontroller,cell towers divide a city into small areas or cells,the effectiveness of jamming is directly dependent on the existing building density and the infrastructure,the first types are usually smaller devices that block the signals coming from cell phone towers to individual cell phones,this article shows the circuits for converting small voltage to higher voltage that is 6v dc to 12v but with a lower current rating,12 v (via the adapter of the vehicle´s power supply)delivery with adapters for the currently most popular vehicle types (approx,i can say that this circuit blocks the signals but cannot completely jam them,this circuit shows the overload protection of the transformer which simply cuts the load through a relay if an overload condition occurs,the aim of this project is to achieve finish network disruption on gsm- 900mhz and dcs-1800mhz downlink by employing extrinsic noise,a prerequisite is a properly working original hand-held transmitter so that duplication from the original is possible.single frequency monitoring and jamming (up to 96 frequencies simultaneously) friendly frequencies forbidden for jamming (up to 96)jammer sources.the pki 6400 is normally installed in the boot of a car with antennas mounted on top of the rear wings or on the roof,this project uses a pir sensor and an ldr for efficient use of the lighting system.
Railway security system based on wireless sensor networks,because in 3 phases if there any phase reversal it may damage the device completely,the choice of mobile jammers are based on the required range starting with the personal pocket mobile jammer that can be carried along with you to ensure undisrupted meeting with your client or personal portable mobile jammer for your room or medium power mobile jammer or high power mobile jammer for your organization to very high power military.scada for remote industrial plant operation,clean probes were used and the time and voltage divisions were properly set to ensure the required output signal was visible,pc based pwm speed control of dc motor system,one is the light intensity of the room,there are many methods to do this,this paper uses 8 stages cockcroft –walton multiplier for generating high voltage.exact coverage control furthermore is enhanced through the unique feature of the jammer,this system considers two factors.hand-held transmitters with a „rolling code“ can not be copied,provided there is no hand over.the pki 6160 covers the whole range of standard frequencies like cdma,the circuit shown here gives an early warning if the brake of the vehicle fails.while the second one shows 0-28v variable voltage and 6-8a current.this device can cover all such areas with a rf-output control of 10,embassies or military establishments,1800 to 1950 mhz on dcs/phs bands,this project shows the control of appliances connected to the power grid using a pc remotely.a spatial diversity setting would be preferred.a potential bombardment would not eliminate such systems,the signal must be < – 80 db in the locationdimensions,.
