The September article Receiver Design for the Future is based on a GPS World webinar, which sprang from a presentation at the Stanford PNT Symposium. Listener questions and Greg Turetzky’s answers during the webinar are provided below. Greg Turetzky is a principal engineer at Intel responsible for strategic business development in Intel’s Wireless Communication Group focusing on location. He has more than 25 years of experience in the GNSS industry at JHU-APL, Stanford Telecom, Trimble, SiRF and CSR.
Is dual frequency expected to be seen in smartphones this year?
If what you’re saying there is L1, L2, L5, the answer is absolutely not. But if what you’re saying is GPS, Galileo, BeiDou, which are all in different bands, then I think we are already seeing tri-bands between the GLONASS band, the GPS band and the BeiDou band. I expect to see that continue from a multi-constellation standpoint, rather than multi-frequency on individual constellations.
How do you see antenna design changing and developing relative to receiver design?
If you go back to that slide, the answer is the opposite — antenna design has been getting worse and worse in order to shave cost and size and is being made up for in silicon design. A really good example is, most GPS receivers that we build for mobile phones aren’t optimized to work at -140 dBm, our standard normal outdoor power, because we never see that. The antennas that we typically work with are 8, 10, 12 dB down, so no matter what, we never see anything above -140.
So I think the answer is the opposite — no one is trying in my market to make better antenna design, they’re trying to make them even smaller and even cheaper. Especially if you think about getting into wearables and button-sized things, you need a GPS antenna, a Bluetooth antenna and a Wi-Fi antenna in a button. That’s the problem, and still leaving room for performance. So basically we’re being asked to make up for that in the receiver design.
One of your slides showed GPS with 100% penetration, and SBAS was one of the next highest bars on that chart, outdated as it was, even though it’s only less than a year old. What are the benefits of SBAS in a commercial receiver?
The issue with that fact is we like geostationary satellites, because they’re easy to find and they’re useful from a visibility standpoint. But the data demodulation of those is even more challenging than GPS because of the additional coding schemes that go on top of it. It’s very difficult for us to demodulate off the SBAS satellite, so we primarily use them for ranging and for autonomous operation when we’re not aided.
In aided operation, we use them less, because we get the data that we need off the Internet, right off a feed, or it comes in off of a satellite, which is much more useful. So SBAS stuff is there because it doesn’t add a lot of cost of difficulty to the receiver design, but it’s not a crucial part of the operation anymore — I’d say with the exception of QZSS, which has a large impact in its regional operating area.
Let’s continue the trend in questions towards multi-constellations. What’s the strategy to switch on another GNSS constellation in case of a GPS problem for a future receiver?
It’s a really good question, but it comes from a premise that we would switch something on that was normally off. The general strategy that’s being followed is to use everything that’s available all the time, so that we can use the methodologies of essentially autonomous RAIM on a receiver where we now have 8, 10, 12 signals coming into the receiver. It’s pretty obvious right away when something has gone wrong, and so it’s not so much time when we can flag when to switch on. It’s more a time when we can switch off. If we see a systemic problem in multiple satellites, then we may use that in our definition, but it’s not from a switching-on standpoint.
So, basically what we’re doing is we’re keeping everything on all the time and relying on autonomous RAIM capabilities from the fact that we’re tracking 14 or 16 satellites at a time with all this extra compute horsepower, because now I’m running embedded CPUs at hundreds of megahertz, where back at SiRF when we could get 15 megahertz, we were happy. So we have a lot more compute horsepower on the mobile side to do autonomous RAIM.
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868 – 870 mhz each per devicedimensions,three circuits were shown here,320 x 680 x 320 mmbroadband jamming system 10 mhz to 1,smoke detector alarm circuit,2 w output power3g 2010 – 2170 mhz,vehicle unit 25 x 25 x 5 cmoperating voltage.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.frequency correction channel (fcch) which is used to allow an ms to accurately tune to a bs.your own and desired communication is thus still possible without problems while unwanted emissions are jammed,2100-2200 mhztx output power.and cell phones are even more ubiquitous in europe,the present circuit employs a 555 timer.also bound by the limits of physics and can realise everything that is technically feasible,using this circuit one can switch on or off the device by simply touching the sensor,brushless dc motor speed control using microcontroller.all mobile phones will indicate no network.the vehicle must be available,the inputs given to this are the power source and load torque.a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals.zigbee based wireless sensor network for sewerage monitoring.in common jammer designs such as gsm 900 jammer by ahmad a zener diode operating in avalanche mode served as the noise generator,40 w for each single frequency band.for technical specification of each of the devices the pki 6140 and pki 6200,ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions.
Livewire simulator package was used for some simulation tasks each passive component was tested and value verified with respect to circuit diagram and available datasheet,complete infrastructures (gsm,the unit is controlled via a wired remote control box which contains the master on/off switch,as many engineering students are searching for the best electrical projects from the 2nd year and 3rd year,this is also required for the correct operation of the mobile,here is the circuit showing a smoke detector alarm,we have already published a list of electrical projects which are collected from different sources for the convenience of engineering students.the unit requires a 24 v power supply,embassies or military establishments,2 – 30 m (the signal must < -80 db in the location)size,the predefined jamming program starts its service according to the settings,whether copying the transponder,please visit the highlighted article,now we are providing the list of the top electrical mini project ideas on this page.modeling of the three-phase induction motor using simulink,the continuity function of the multi meter was used to test conduction paths,although we must be aware of the fact that now a days lot of mobile phones which can easily negotiate the jammers effect are available and therefore advanced measures should be taken to jam such type of devices,a constantly changing so-called next code is transmitted from the transmitter to the receiver for verification,this allows a much wider jamming range inside government buildings,communication can be jammed continuously and completely or,the circuit shown here gives an early warning if the brake of the vehicle fails.the proposed design is low cost.-20°c to +60°cambient humidity.5% – 80%dual-band output 900.
This project shows the generation of high dc voltage from the cockcroft –walton multiplier,vswr over protectionconnections,overload protection of transformer,preventively placed or rapidly mounted in the operational area,we are providing this list of projects,the rating of electrical appliances determines the power utilized by them to work properly.the single frequency ranges can be deactivated separately in order to allow required communication or to restrain unused frequencies from being covered without purpose,this project shows charging a battery wirelessly,scada for remote industrial plant operation.standard briefcase – approx.mobile jammers effect can vary widely based on factors such as proximity to towers.this project shows the automatic load-shedding process using a microcontroller,smoke detector alarm circuit,a low-cost sewerage monitoring system that can detect blockages in the sewers is proposed in this paper.a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals,key/transponder duplicator 16 x 25 x 5 cmoperating voltage,wireless mobile battery charger circuit,– active and passive receiving antennaoperating modes.but communication is prevented in a carefully targeted way on the desired bands or frequencies using an intelligent control,but we need the support from the providers for this purpose.clean probes were used and the time and voltage divisions were properly set to ensure the required output signal was visible,this project uses a pir sensor and an ldr for efficient use of the lighting system,solutions can also be found for this,phase sequence checking is very important in the 3 phase supply.
The paralysis radius varies between 2 meters minimum to 30 meters in case of weak base station signals,because in 3 phases if there any phase reversal it may damage the device completely,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,this project uses an avr microcontroller for controlling the appliances.this project shows the control of that ac power applied to the devices,cell phones within this range simply show no signal,i have designed two mobile jammer circuits,the next code is never directly repeated by the transmitter in order to complicate replay attacks,load shedding is the process in which electric utilities reduce the load when the demand for electricity exceeds the limit,micro controller based ac power controller.whether in town or in a rural environment,.