After a four-month sabbatical and the GPS World servers back in order, I’m back writing on a regular basis. I’ve been super busy on different GPS/GNSS-related products, conferences and various GPS/GNSS applications.
Let’s take a look at some of the technologies and events that were significant in 2012 and some that will be significant in 2013 for high-precision GNSS users.
House Representative Anna Eshoo, ranking member on the House Subcommittee on Communications and Technology, who in September 2011 wrote to the NTIA’s Larry Strickland asking Strickland to find a way for LightSquared and GPS to coexist, said it best a year later (November 2012):
“What happened to LightSquared is disappointing, but unfortunately that ship has sailed.”
Now all that’s left are negotiations regarding GNSS receiver standards and/or a frequency guard band around GPS L1, both of which are moving at a snail’s pace. Regardless, you can bet that GNSS receiver designers are taking this experience to heart and tightening up their filtering as much as possible. The more difficult problem to solve is the augmentation services offered in the MSS band (such as Trimble’s OmniSTAR, Deere’s Starfire and just-introduced Terrastar), all of which broadcast their correction signals in the MSS band at low-power satcom power levels (as opposed to high-power terrestrial power levels).
You can pretty much dismiss the LightSquared-proposed spectrum sharing proposal from last fall. It’s just another desperate move from a desperate company. If you have a few minutes, you can listen to the NSPS (formerly ASCM) Radio Hour show I participated in on October 8, 2012, where we discuss this issue.
FCC UHF/VHF Narrowbanding Rule
Hidden behind the LightSquared issue over the past two years has been the FCC narrow-banding ruling that took effect on January 1, 2013. Initially adopted in 1995, the narrowbanding ruling has been around for a number of years. In fact, equipment suppliers have been required to offer narrowbanded (12.5kHz vs. 25kHz spacing) radios since 1997. In 2004, the FCC set the January 1, 2013 deadline for users to comply.
The FCC’s webpage on the narrowbanding ruling shed some light on the rationale behind it, but narrowbanding doesn’t specifically target RTK users so there’s not any RTK-specific information contained in the FCC documents. The bottom line is that the FCC is trying to allow more users in the same spectrum, similar to trying to fit more cars on a highway by splitting lanes in two. The problem with this, from a user standpoint, is that some vehicles won’t fit in the new, narrower lanes and therefore aren’t legal to use any longer. That’s the case with most UHF/VHF RTK base stations.
To be clear, the narrowbanding ruling doesn’t affect UHF/VHF radios on your rover (receiving radio) GPS/GNSS receiver. I’m talking about the base station UHF/VHF radio. The ruling states that your UHF/VHF base station radio must be able to broadcast at 12.5kHz vs. 25kHz, essentially utilizing half the spectrum. Your UHF/VHF base radio can still broadcast at 25kHz if it broadcasts at 19,200 baud. Since January 1, 2013, it is illegal to broadcast at 4,800 or 9,600 using 25kHz spacing. The reality is that it becomes complicated when trying to broadcast at 19,200 baud at 25kHz spacing. Radio range is reduced and communication protocols (compatibility) become an issue. The reality is that you’ll likely need to replace your UHF/VHF base radio in order to stay compliant with the FCC rules.
Just a few weeks ago (January 7, 2013), I was a guest on the NSPS Radio Hour to discuss the FCC narrowbanding rule. I invited Charlie Branch from Pacific Crest Corporation, a major supplier of VHF/UHF radios for RTK users, and Mark Silver from IGAGE Corp, a Pacific Crest dealer, to discuss their thoughts on the FCC narrowbanding rule and their experience with equipment compatibility. It is a great discussion on the subject and well worth listening to if you’re interested in learning more about the narrowbanding rule and how it affects RTK users.
Lastly, you might also be interested in this presentation from Charlie Branch on the FCC narrowbanding rule.
Low-Cost RTK Receivers
At the GPS World dinner during the Institute of Navigation GNSS conference last September, Dr. Todd Humphreys predicted that RTK GNSS would be available in mobile phones by the year 2020. As I’ve written before, the challenge with this is not really the quality of the GPS receiver used in mobile phones (some of the key engineers at Broadcomm, who supply the GNSS chip to Apple, used to design RTK receivers at Ashtech), but rather the poor quality antennas that mobile phone designers choose to use. Instead of RTK inside the mobile phone, I think small RTK “pucks,” a few inches in diameter, are more practical and realistic and will become common and easily interfaced to mobile phones (or other mobile devices) via Bluetooth. I think you will start seeing these within the next three years.
With four Galileo IOV (in-orbit validation) test satellites in orbit that will be converted to operational satellites, Europe’s Galileo is on its way to becoming a viable satellite navigation system for high-precision apps. Launch of production satellites is scheduled to begin later this year and scheduled to occur every three months, launching in pairs. With an aggressive launch schedule, 18 satellites are predicted to be in orbit by the end of 2015, a little more than two years from now.
I’m very bullish on Galileo because, like GPS, it supports the new L5 signal, which will lead to less expensive dual-frequency, dual-constellation receivers. It’s clear that the European Union is committed to Galileo, and it would be difficult for them to shut down the project after advancing as far as they have.
Modernizing GPS, on the other hand, is moving very slowly. Galileo already has more L5-capable satellites in orbit than GPS. My 2010 prediction that 18 Galileo satellites and 12 GPS satellites would provide the high-precision user community with a full 30-satellite constellation broadcasting L1/L5 signals by 2015 may not materialize. However, the weak link might end up being delays with the GPS program rather than a lack of commitment from the European Union with its Galileo program.
Last August at a CGSIC (Civil GPS Service Interface Committee) meeting, I heard rumblings of three GPS launches this year (2013). Sadly, I don’t think this is going to materialize. I think we’re on pace for a single launch this year, again. Budget, launch pad scheduling and a healthy GPS constellation continue to be the culprits.
There’s also a bit of second-guessing happening with respect to GPS signals. Earlier this month, Don Jewell wrote a piece entitled “2C or not 2C: An Important Signal Question.” While the delay in launching next-generation GPS satellites may have saved the U.S. government some money, I think it has put the L2C signal in peril. There were high hopes for L2C, as the second civil GPS signal, when it was conceived in the 1990s. But it’s been seven long years since the signal was deployed on the first GPS II-RM satellite in 2005, and there are only a total of 10 GPS satellites broadcasting L2C today. That’s not enough, and it’s hard for receiver manufacturers and the civilian user community to take L2C seriously when it appears the U.S. government is not taking it seriously.
Some sort of positive traction with L2C must happen soon, or it will risk being ignored as it is overtaken by the new L5 signal that is supported by up-and-coming GNSS like Galileo and Compass/BeiDou.
UAVs (Unmanned Aerial Vehicles)
The United States is the last major geographic region (that I’m aware of) where UAVs are illegal to use by commercial entities. Service companies in other countries are going crazy with UAVs in offering mapping services (for instance, in mining and agriculture). The Federal Aviation Administration (FAA) is working on establishing rules by 2015 that will allow commercial entities to utilize UAVs in the U.S. This will turn the market for digital mapping imagery upside down. It will become very easy and inexpensive for people to obtain quick-n-dirty imagery for mapping purposes with a very quick turnaround.
Thanks, and see you next month.
Follow me on Twitter at https://twitter.com/GPSGIS_Eric