With the possibility of L1 being turned off after 2020, what do you look for in the specs to see if the unit would still function after 2020? If L1, L2 and L2C are listed, does that mean it will still work if L1 is turned off, or does it have to say L5, too?
> With the possibility of L1 being turned off after 2020, what do you look for in the specs to see if the unit would still function after 2020? If L1, L2 and L2C are listed, does that mean it will still work if L1 is turned off, or does it have to say L5, too?
I think you're talking an 8 year life span for this unit, I would venture to say that in 8 years these concerns will be pre-historic and obsolete. The GPS world is changing so rapidly that you will be facing a whole new set of issues by then. 8 years is a very long time for a modern GPS reciever.
I remember when I bought my first desktop computer, I drove down to D.C. to visit my buddy who worked for Compaq. I ordered all the bells and whistles, Windows 3.1, Dos 6.2, math co-processor, yada, yada yada. I paid $3700 and thought I was on the cutting edge. 2 weeks later I was reading the computer section of the Times and I noticed the same computer with all the extras on sale for $1299. The point I'm trying to make is that I was obsolete in 2weeks. I think that's the nature of the beast when purchasing technology and you can't take it personally.
I probably didn't answer your question and I apologize but that's the way I would look at it.
Ralph
I agree. When they turn off L1 in eight years you will be lucky if the GPS is still hanging on. It'll probably be 100 times better and 50 times cheaper by then. However, for "future-proofing there are a couple important things that I would look for; which would consist of L5 and L2C. In addition, I would get a system that has dual-purposes. The first purpose as an RTK or VRS system that will do survey-grade work. The second purpose would be GIS or GIS-type location work. Both Leica and Carlson off the top of my head have these options in the same sub-centimeter unit. Like it or not, GIS is here to stay, why not have a unit that can do both?
> I agree. When they turn off L1 in eight years you will be lucky if the GPS is still hanging on. It'll probably be 100 times better and 50 times cheaper by then. However, for "future-proofing there are a couple important things that I would look for; which would consist of L5 and L2C. In addition, I would get a system that has dual-purposes. The first purpose as an RTK or VRS system that will do survey-grade work. The second purpose would be GIS or GIS-type location work. Both Leica and Carlson off the top of my head have these options in the same sub-centimeter unit. Like it or not, GIS is here to stay, why not have a unit that can do both?
:good: :good:
Very good Suggestions.
Ralph
They aren't turning L1 off. L1 is the foundation of GPS and will be for the foreseeable future.
The 2020 date is with regards not supporting the L2 semicodeless techique, of which L2C is taking its place. Same frequency, different technique.
As long as the receiver supports L2C, you're good to go until your retirement years.
Which one depends on how much you want to spend. The premium-priced receivers support L1, L2C, L5, glonass, galileo but they are high $$. If the geographic area you are working in allows you to get by without glonass, then you can buy a L1/L2 GPS receiver for a fraction of the cost of a premium receiver.
> With the possibility of L1 being turned off after 2020, what do you look for in the specs to see if the unit would still function after 2020? If L1, L2 and L2C are listed, does that mean it will still work if L1 is turned off, or does it have to say L5, too?
You Will Need L1 For The Next 8 Years, At Least
Currently it is L1/L2 GPS and GLONASS.
You are looking at least 4 years until Galileo helps at all.
Probably 6 years until L2C makes a difference, and 8-10 until L5 kicks in.
I have not priced anything new, but the difference to get it all now is not too much more. It is your choice, and in fact several companies are offering upgradeable packages. The only upgrade requirement is to pay extra to turn existing capabilities on.
Again it is your choice if you want to be working 4-8 years from now with 4-8 year old equipment.
I doubt they turn L1 off in 8 years anyway. L2-L5 differencing will not be more accurate than L1-L2. L1-L2-L5 differencing will be very precise. Until there are 24 L5s in the sky, L1 will be required. I put the 24 L5 satellites date to be 12 years off. Plus once you turn off L1 the remaining 8 L1/L2 satellites will be fairly useless in L2 only mode. That means L1 will be useful for at least 15 years. Current and future budget cuts mean receivers will be 10 years ahead of satellites for quite some time. That means more than half the receivers purchased in 2012 will be worn out before the get to use their full potential.
Paul in PA
You Will Need L1 For The Next 8 Years, At Least
Paul,
I sure hope you are right.
I hope to use my receivers as long as I possibly can.
Jimmy
You Will Need L1 For The Next 8 Years, At Least
The future of the US aviation navigation system is based on GPS L1 and L5. I will bet you any amount of money L1 will be around 30 years from now. The faa doesn't like to change.
> Currently it is L1/L2 GPS and GLONASS.
>
> You are looking at least 4 years until Galileo helps at all.
>
> Probably 6 years until L2C makes a difference, and 8-10 until L5 kicks in.
>
> I have not priced anything new, but the difference to get it all now is not too much more. It is your choice, and in fact several companies are offering upgradeable packages. The only upgrade requirement is to pay extra to turn existing capabilities on.
>
> Again it is your choice if you want to be working 4-8 years from now with 4-8 year old equipment.
>
> I doubt they turn L1 off in 8 years anyway. L2-L5 differencing will not be more accurate than L1-L2. L1-L2-L5 differencing will be very precise. Until there are 24 L5s in the sky, L1 will be required. I put the 24 L5 satellites date to be 12 years off. Plus once you turn off L1 the remaining 8 L1/L2 satellites will be fairly useless in L2 only mode. That means L1 will be useful for at least 15 years. Current and future budget cuts mean receivers will be 10 years ahead of satellites for quite some time. That means more than half the receivers purchased in 2012 will be worn out before the get to use their full potential.
>
> Paul in PA
So, L2C will "replace" L2, and L5 will "replace" L1? I'm looking at the Hiper II or Sokkia GRX1 (same unit, different color), and it does not appear to include L5.
I hate to buy a unit that might be obsolete in 8 years. I'm one of those guys that expects my equipment to work for as long as I can remain competitive using it, not fail from a "planned obsolescence". I get what your saying, that the aviation industry and the consumers grade stuff, will make it unlikely that L1 will really be switched off in 2020. But with the supposed "spectrum crunch", their might be pressure on the Airforce to make those units obsolete so the new "better filtered" units will be used, freeing up more spectrum. I know "things will change", but I just can't see paying $20,000 for something that *might* be a paper weight in 8 years ...
You Will Need L1 For The Next 8 Years, At Least
I think your dead on Paul.
Gallalio sp? is a joke. Last time I checked they only had like 2 sats up. With all of the econimic/political unrest in that area of the country I doubt this system gets off the ground in the next 20 years.
I haven't heard of any real positives out of the L2C. I and everyone I have talked to get better results with the L2C off, maybe once we are carrying more L2C it will be better.
L5 is the real one that I think is worth waiting for. Seeing that it will be broadcasting @ 750mhz, I bet you could use it in some less than ideal conditions.
Differencing To L5
L5 may begin to make a difference when 3 L5 satellites are in view with reasonable geometry. L1/L2 should take care of the clock differences, so you may not need the 4th satellite for differential ranging and atmospheric corrections. But such a low number would be useless the majority of the time under canopy.
L2C may be a non starter, with so few L2C satellites and everything L5 from now on. L2C would allow cheaper L1-L2 receivers, essentially one could put a straight L1 board and a straight L2 board in a box, mean out and claim L1-L2 capability, but not the same precision as an L1/L2 receiver where the resolutions are intertwined in the software. In other words a rather precise GIS receiver, but not a precise surveying instrument. By having a top quality receiver as your base and post processing the precision would improve just as some use L1 only receivers in close proximity to one or more L1/L2 receivers.
You want the full GPS and GLONASS spectrum and enough channels but forget abour Galileo, I would recommend Ashtech with the added ability of L1 ranging (BLADE technology) to SBAS satellites. I have yet to see it transfer over to Trimble or be licensed to others. But I believe it to be software not hardware dependant. What will be of great benefit is I believe the plan is to add a second frequency correction to future WAAS (SBAS) payloads on geostationary satellites.
Paul in PA
You Will Need L1 For The Next 8 Years, At Least
> Paul,
>
> I sure hope you are right.
>
> I hope to use my receivers as long as I possibly can.
>
> Jimmy
I am with you Jimmy... I want to use the ones I have for as long as I can.
No, future civilian signals are L1 (eventually L1C), L2C, and L5.
As long as the receiver you buy today can utilize L2C, it won't be obsolete in 8 years.
An L1/L2C receiver will operate perfectly fine for the rest of your career. If you want better RTK performance, then an L1/L2C/L5.
L5 is not a must, but I think it will be very nice because other systems support L5, like Galileo and the Chinese one. But again, you pay for it because it's a premium feature.
Spectrum crunch won't affect L1, L2 or L5. The lightspeed situation has shown that the government is very interested in protecting GPS.
> So, L2C will "replace" L2, and L5 will "replace" L1? I'm looking at the Hiper II or Sokkia GRX1 (same unit, different color), and it does not appear to include L5.
>
> I hate to buy a unit that might be obsolete in 8 years. I'm one of those guys that expects my equipment to work for as long as I can remain competitive using it, not fail from a "planned obsolescence". I get what your saying, that the aviation industry and the consumers grade stuff, will make it unlikely that L1 will really be switched off in 2020. But with the supposed "spectrum crunch", their might be pressure on the Airforce to make those units obsolete so the new "better filtered" units will be used, freeing up more spectrum. I know "things will change", but I just can't see paying $20,000 for something that *might* be a paper weight in 8 years ...
TPR - If you leaning toward a Hiper II you should check out Javad's Triumph receiver. Let's face it. Javad got Topcon going with the Hiper series. Heck, He got Trimble going with the 4000 series.
A lot of people remember that Javad also tried to get LightSquared's scheme going.
The USAF has trhe option of dropping support of the P(Y) code in 2020 that is used by folks doing codeless and semi-codeless solutions (like cheap consumer chips). L1 is not being dropped, and the P(Y) code drop is still only an option.
Look up the federal registetr notice from 2008 ,and I thin kGPSWorld did some articles about the 2020 optional changes.
Let's say an antivirus software company goes and testifies before a governement hearing on behalf of a company that wants to legalize computer viruses. Nice.
> The USAF has trhe option of dropping support of the P(Y) code in 2020 that is used by folks doing codeless and semi-codeless solutions (like cheap consumer chips). L1 is not being dropped, and the P(Y) code drop is still only an option.
> Look up the federal registetr notice from 2008 ,and I thin kGPSWorld did some articles about the 2020 optional changes.
Thanks, Farsites. That clears up a lot. I thought the option was to drop/replace L1.
This. I'm going to boycott Javad for the rest of my career. There are too many companies that stood by their customers to ever give Javad a cent.
And what was bad with Lightsquared? Did that scare you? Didn't even phase me. What I was saying was Javad is a great receiver. Just to check it out. He was the only one trying to work out a solution with lightsquared. Every other manufacturer just sit back and waited/did nothing. He actually did something.
