To download see: http://www.cambridgewireless.co.uk
Friday, 26 November 2010
To download see: http://www.cambridgewireless.co.uk
Thursday, 1 July 2010
Friday, 23 April 2010
Satellite navigation systems take their location cues from 30 GPS satellites that circle the Earth twice a day transmitting status, date and time, and orbital information. Soon there will be around 100 satellites to lock on to as GPS is joined by global constellations from Europe (Galileo), Russia (GLONASS), and China (Compass).
GPS wasn't built to help us find our way to the shops - it was a Cold War project funded by the US Department of Defense to ensure that nuclear submarines could surface and target their missiles accurately. There are strategic rumblings about the new satellite constellations too, but the current consensus is that civilians have most to gain from more accurate and reliable location and tracking applications. That's if receiver designers can get the power consumption under control.
Russia's GLONASS system used to be famous for its satellites failing faster than they were launched, but since last month it has had 24 functioning satellites in orbit. Meanwhile, Europe's much-delayed Galileo system will have 14 satellites operating by 2014, according to the European Commission, with the full 30 available by 2017. The US GPS system is being modernised to become GPS III by 2013, with additional navigation signals for both civilian and military use. Information about China's Compass system is sketchier - it was going to be a regional system but is now understood to be global.
'All this activity is great news because whatever the application, there will potentially be multiple constellations to get a position fix from, which will help with signal integrity in safety-critical environments such as maritime, aviation or rail, and accuracy for mobile phone users in urban areas,' says Andrew Sage, director of Helios, a consultancy specialising in satellite navigation.
A GPS receiver should be able to 'see' at least four GPS satellites anytime, anywhere on the globe and establish three position coordinates (latitude, longitude, and altitude). But in city streets hemmed in by tall buildings, a receiver is unlikely to be able detect more than two satellites and the signals will often have bounced off structures.
'For the average pedestrian, the position fix can be a long way out and very unpredictable,' says Sage. 'Most users don't see that today because GPS receivers match us to maps and smooth the errors out. But if you are walking around a city and not on a road in a car, multi-path reflections are a problem.'
The more satellites visible from within these 'urban canyons', the easier it is to carry out consistency checks on the received signals. 'Even when you can't isolate the multipath-contaminated signals, the more signals you have, the more your errors average out,' says Dr Paul Groves, lecturer in global navigation satellite systems (GNSS), navigation and location technology at UCL.
Better GNSS integrity would enable new applications, such as road-user charging, enforcing bail conditions and pay-as-you-drive insurance. 'Clearly, if position information might be used as legal evidence, it has to be reliable,' says Groves.
The delayed arrival of Galileo and the resurrection of GLONASS have complicated matters for receiver makers. Galileo was designed to offer the simplest possible upgrade path from GPS to a dual-constellation system. Agreements were made to put the carrier frequencies of the main open services in the same part of the spectrum as GPS, at around 1575MHz, so receivers could share the same radio, analogue components and antenna. Both systems also send their signals using a spread-spectrum code-division multiple-access (CDMA) approach. GLONASS uses a frequency-division multiple-access coding technique (FDMA) and a main open-service carrier frequency of 1602.2MHz.
Thursday, 25 June 2009
But imagine that you have a navigation tool or gadget which acts as your own personal travel guide. It has satellite navigation, so when you get into your car it can direct you to where you want to go. It can choose the most carbon-efficient route and make sure you avoid crowded town centres, traffic jams and road works. It can let you know where the next petrol station is, and whether there is an Italian restaurant near your hotel. Before you arrive you will know which of the town car parks have spaces left. And when you've finally parked the car, take your guide with you and it will direct you, on foot, to your final destination.
For anyone who has found themselves stuck in a traffic jam, or has been unable to find a car park in a busy town centre, or has got lost on foot, it sounds too good to be true. Yet the technology to make it happen is already here. So why aren't we all carrying such a device in our pockets?
The question which then arises is that why the universal travel widget isn't at hand. One of the reasons for that is that several different worlds have to collide and co-operate. First of all there is a massive competition together with a huge confusion regarding the platforms in which such device can be built on. To start with we have got proprietary platforms like TomTom and Garmin, and then we've got the at least five major mobile phone operating systems.
The obvious competition between these different platforms has instigated some suspicion but apart from this the mobile companies also have yet to ¬recognize the potential of phones as navigation devices.
You can argue that many mobile phones are already GPS-enabled but in my opinion this doesn't necessary make them effective at navigation. For instance try using your blackberry as a navigation device and you’ll find that battery has quickly drained out. The mobile phone world is slowly coming to terms with the needs of navigation on mobiles, such as better ¬battery life and bigger screens. Infact GPS alone doesn't offer the precision needed to navigate pedestrians, and so to be useful needs to be combined with another positioning service such as Wi-Fi. This has been done with the iPhone, for example.
The accuracy and granularity of data used in satellite navigation systems is very critical and has to be improving all the time. The real problem lies in integration where the data needed to provide a coherent information service to a navigation device is held by different organisations in a number of different places. While there are companies that are providing some location-based information such as information about ATMs, speed cameras, train times or tourist sites but there is no company in my knowledge that offers everything.
Combining all the information and hence provided through a single device at a one point of time that information isn't going to be easy. The challenges which lies in this are not solely technical for example there's a data aggregation problem to bring it altogether, including highway changes, updates from local authorities and then there's a physical problem in gathering all that up.
Even if the above issues are solved there is still a major part of the problem which is revenue. How one would make money out of integrated Satnav device? There's a difference between what can be done technically and a viable ¬product that can be sold. How do you turn that into something that fits in a business model?"
Organisations that have valuable data rarely want to give it away for free, licences to reuse companies or government’s mapping data commercially are expensive. Similarly, there is no incentive for the Highways Agency or local authorities, for example, to share information about traffic conditions. Even the government website Transport Direct, which provides free up-to-date transport information, has restrictions on the integration of its content with other services.
So now you may realize that how trying to highlight the potential of the problem. It’s a mammoth task to bring all the above information together into one place as everyone wants their pound of flesh because everyone has developed their own data infrastructure and it's just very difficult to get them to agree.
I certainly hold the opinion that inspite of all these hiccups the demand for an all-in-one travel service almost certainly exists. People simply really want a so called integration or integrated device which can work across different ¬locations i.e. home, work, on the move etc.
It’s evident from the above facts that the emergence of a ¬genuinely integrated solution will depend on a government initiative to force public sector organisations such as Highways Agencies, Transport for London and local authorities to collaborate, or on a private sector organisation taking a ¬commanding lead in terms of developing location technologies.
Google is one such company which is creeping up with a whole series of ¬initiatives that are steadily putting the pieces in place. Best example for this is Google Maps which are now readily available on all mobile platforms and is integrated with traffic data from the Highways Agency. Not only this, the Google Maps application interface (API) allows third parties to build their own applications as well.
Google, no doubt is leading with an example in terms of it’s initiatives towards serving the customers in best possible way. Google certainly knows what the customers want which I believe a mini innovation in these current economic climate.
Location has always been such an absolutely fundamental framework for our lives, and we inevitably must embrace tools that allow us to manage that. I envisage a society in 20 years' time revolutionised by the ability to know all the location based information.
Wednesday, 17 December 2008
Advances in information technology are fundamentally changing the way military conflicts are resolved. The ability to transmit detailed information quickly and reliably to and from all parts of the globe will help streamline military command and control and ensure information superiority, enabling faster deployment of highly mobile forces capable of adapting quickly to changing conditions in the field. Satellite communications play a pivotal role in providing the interoperable, robust, "network-centric" communications needed for future operations.
Military satellite communications (or milsatcom) systems are typically categorized as wideband, protected, or narrowband. Wideband systems emphasize high capacity. Protected systems stress antijam features, covertness, and nuclear survivability. Narrowband systems emphasize support to users who need voice or low-data-rate communications and who also may be mobile or otherwise disadvantaged (because of limited terminal capability, antenna size, environment, etc.).
For wideband communication needs, the Wideband Gapfiller Satellite program and the Advanced Wideband System will augment and eventually replace the Defense Satellite Communications System (DSCS). These satellites will transmit several gigabits of data per second—up to ten times the data flow of the satellites being replaced. Protected communications will be addressed by a global extremely high frequency (EHF) system, composed of the Advanced Extremely High Frequency System and Advanced Polar System. These systems are expected to provide about ten times the capacity of current protected satellites (the Milstar satellites). Narrowband needs are supported by the UFO (Ultrahigh-frequency Follow-On) constellation, which will be replaced by a component of the Advanced Narrowband System
Although the EHF band is a relatively lightly used part of the electromagnetic spectrum (30-300 GHz), it is for good reason. Atmospheric attenuation is the biggest problem faced in this band, especially around 60 GHz, however the frequencies are viable for short distance terrestrial based communication links, such as microwave Internet and telecommunication links (which already operate in this band). Millimetre wave radar, probably best known as the radar that can see through your clothes but not your skin, also operates in this band.
Designed to avoid problematic frequencies that are more susceptible to attenuation, but accepting increased overall atmospheric attenuation, are an increasing number of military and civil satellite systems that are using this band for uplink and downlink, as well as inter-satellite communication. Inter-satellite communication is really where EHF equipment shines (no atmosphere, small antennas, high data rates).
Civilian systems are currently around the Ku band (Intelsat), providing data rates of up to 2-4 Mbps (14 GHz uplink, 12 GHz downlink) however these rates have still to trickle into everyday user's hands for remote and mobile Internet access. It is more common that an aggregator will access this link/rate and use that to then portion out local Internet access. Systems such as this are in use for remote Australian territories like Cocos and Christmas Islands, and formed the backbone of Boeing's stillborn Connexion in-flight Internet access. High ongoing access costs (basically a share of the overall cost of the satellite) and limited access slots help keep the technology away from everyday use at this time. Militaries and governments around the globe also lease access on these circuits when they need the added capability, with Intelsat and Inmarsat systems being used in the first Gulf War.
Advanced EHF is designed to provide 24 hour coverage from 65 North, to 65 South across the K and Ka sub bands, and when combined with the prototyped Extended Data Rate (XDR) terminals and systems, will offer up to 8.2 Mbps data rates for around 4,000 terminals in concurrent use per satellite footprint (whether that scales to 12,000 systems in concurrent use globally isn't clear from source material).
Within the tri-satellite constellation, inter-satellite EHF links will allow terminals on opposite sides of the globe to communicate in near real-time without the use of a terrestrial link. Combined with smaller, directional antennas and the various options for anti-jamming technology, it represents a significant military capability for the US.
Already plans are being drawn up for the Transformational Satellite Communications System (T-Sat) which will replace Advanced EHF starting sometime in 2013, however it is already facing funding troubles. This could be problematic, with Advanced EHF still struggling to reach capability and the final launch not scheduled until April 2010. Dropping the fourth satellite of the Advanced EHF constellation has been planned to give the USAF time to implement T-Sat more rapidly.
If GPS and remote imaging (think Google Earth) have proven anything, it is that technology initially developed for military purposes, and extremely expensive for initial civil use, will eventually reach the point where it forms part of our daily lives without us ever being conscious of the massive investment to get to that point.
Saturday, 25 August 2007
A heading of news article yesterday read: "European mobile operators are looking for economic ways of launching broadcast mobile TV services directly to handsets". This made me wonder, if there is a strong case for Mobile TV via Satellite?
Couple of days back, 3 Italia reported that it had 719,000 people using its DVB-H service by August 22, which is about 9.4 percent of its 7.68 million customer base reports Dow Jones in Italian. The figure is a good sign—at the beginning of June it was 600,000 and back in March it was 250,000, or about 3.7 percent of the subscriber base. So this proves that some people are using Mobile TV if available.
The only popular satellite Mobile TV i am aware of being used practically (please correct me if you know more) is the S-DMB being used in Korea.
According to a report in Moconews, currently some 7 million people in S. Korea are watching mobile TV--that equates to one in every seven residents of the country--but none of the operators offering DMB services has yet to make any money. Each of the six terrestrial DMB operators has piled up an accumulated loss of between $22 million and $33 million. The only mobile TV operator that charges for its service is SK Telecom-owned TU Media, which offers its DMB service over a satellite-based system (S-DMB). It has 1.2 million paid subscribers, but TU says it needs at least 2.5 million to break even in operation. That’s before it can even start to recoup its $435 million investment in satellites and networks.
The European Space Agency (ESA) has joined the DVB-H party by funding development of technologies for broadcasting TV to mobiles via satellite. ESA has called its standard DVB-SH (Digital Video Broadcast - Satellite, Handheld) and envisages using satellites to send out video at 2GHz to 4GHz (S-Band). Terrestrial repeaters would be used to give indoor coverage. Eutelsat has commissioned a new satellite to be launched in 2009, with the intention of broadcasting DVB-SHb - though it's hedging its bets by claiming it's for multimedia distribution rather than any specific technology or application. Much of the technology needed by DVB-SH doesn't yet exist, so the ESA will be issuing invitations to tender (ITT) for companies that want to have a go at developing them. First up will be a mobile chipset capable of receiving and decoding DVB-SH version b signals. The ITT is due to be published in the next few months.
Finally i found a good report on BetaNews detailing the pros and cons of Satellite Mobile TV:
It's an ambitious idea, and it's not nearly a done deal. But yesterday, a proposal was introduced before the European Parliament for a timetable by which the EU would select a few choice service providers, for the precious and narrow spectrum it will be making available for the entire continent. It will require the consent and cooperation of all 27 member states - something the EU rarely gets even with less ambitious proposals.
Here's what it means: Last February, the EU established two small chunks of radio spectrum - 1980-2010 MHz and 2170-2200 MHz - as reserve space for future MSS broadcasting. Under normal EU law, member states would each have the right to select their own service providers for satellite TV and radio service for their respective countries. In fact, if the EU were to change its mind now and do nothing, that's what EU states would do next.
But there's two big problems: First of all, no single EU country is very big, geographically speaking, compared to the whole of Europe. A satellite signal covers a very broad portion of the Earth, so any service provider licensed for, say, France could probably have its signal picked up in southern Finland. Simply put, the laws of physics dictate a wide coverage area that technology cannot circumvent...unless every mobile TV receiver in Europe were custom-built for each member country. (If you're thinking like a manufacturer of DVD consoles, you might not be too opposed to trying that.)
Even if France's signal and England's and Bulgaria's and all the others could be picked up everywhere else - which, if you think about it, will be the case anyway - Bulgaria's service provider wouldn't want its signal overlapping England's. And that leads us to the second big problem: There's not enough MSS spectrum available in the 2 GHz band to go around.
So the European Union is stepping in, or at least attempting to. But in order for member states to allow it to do so, it has to formally present its case to those states for why it has the authority to do so. Imagine if, under a different style of US constitution, in order for the federal government to make its case for regulating the public airwaves, it had to get all 50 states' consent to giving up their own rights to do so individually.
Thus a large part of the EU proposal yesterday explains - as it must do under European law - why it's claiming the authority to propose a national selection process for MSS providers.
For its claim to qualify as valid, it has to meet two tests under the EU constitution. First, the claim must meet the Subsidiarity Principle: essentially, that the nature of the job at hand means it can be performed better by the EU than by all the 27 states acting independently. In other words, the EU has to prove it can do the job not because it's better at these sorts of things, but because the problem at hand makes a single body better suited to the task.
Here is where the EU has physics on its side: Satellite signals cover broad territory, and states' boundaries do not. "Selection and issuance of rights over the same spectrum to different satellite operators in different Member States would prevent satellites from covering their natural footprint," the EU proposal reads, "which by nature covers a large number of countries; it would risk fragmenting the satellite communications market and eliminate the natural advantage of satellites compared to other modes of communication. The mobile character of the services involved also means that citizens travelling in the EU should benefit from the availability of such services throughout the EU."
Second, the EU's case must meet the Proportionality Principle. This means it can't claim more authority than it needs to do the job...and once the job is done, it steps out of the way. In other words, it can't appoint a permanent commission like the FCC.
In making that part of the case, the EU goes on, "The proposal will create a mechanism for coordinating the selection and definition of certain conditions to be attached to rights of use of spectrum. It will not touch upon the right of Member States to grant the authorizations to use the spectrum or to attach specific conditions applying to the provision of services in areas which are not harmonized. Member States will be closely involved in elaborating the details of the selection procedure."
Here is where critics say the EU's case may fall apart. In order to win the authority to drive the MSS adoption process, the EU is limiting itself to driving the selection process for prospective service providers. Once that job is done, it's leaving it up to member states to apportion per-country licenses to those companies, for channels which the EU would already have selected as well.
On the one hand, it doesn't make sense. In order to sell its plan, the EU is leaving open the option for member states to deny licenses. But assuming a state does so, how could it block the reception of a signal from a service provider whose license was denied? That might take a technological solution...which brings up the whole "per-country" manufacturing option for MSS receivers again.
On the other hand, only such a hare-brained scheme might just work, because member states don't want to be perceived by their citizens as ceding any part of their authority to a federal institution. Giving them the right to say "no" could be a kind of ceremonial concession, not unlike the establishment of a constitutional monarchy where the monarch is essentially a face on a coin - which is a state of affairs not unfamiliar to member states.
"Since industry so far could not agree on a single standard for mobile TV, commercial launches of mobile TV are delayed," reads a statement from the EU's central authority in Brussels last month. "Europe's competitors, most notably from Asia, have made significant progress - partly due to state intervention - and Europe risks losing its competitive edge unless sufficient momentum is achieved. This is why there is a need to develop a 'blueprint' for mobile TV in Europe."