GPS III is Coming

I doubt that “all our existing GPSr’s will be able to use the new system”. In fact, since digitaltrends is cited in the original post, I’ll quote some content from one of their other articles.

“So here’s the downside to all these GPS improvements: They take time to develop, test, and get up into orbit. Once the systems are in space, users on the ground will need to upgrade to new GPS receivers that can use the new signals. That means your current smartphone isn’t going to support L2C, L1C, or L5, nor are your handheld GPS or the satellite navigation system in your car. You’ll have to buy new kit.”

I may have been premature in my compatibility statement since there is some confusion on this point. Thanks for the possible correction.

Part of my post came from this Wikipedia article which states:

"New Civilian L1 (L1C)
L1C is a civilian-use signal, to be broadcast on the same L1 frequency (1575.42 MHz) that contains the C/A signal used by all current GPS users.

L1C broadcasting will start when GPS III Control Segment (OCX) Block 1 becomes operational, currently scheduled for 2022.[29][18] The L1C signal will reach full operational status when being broadcast from at least 24 GPS Block III satellites, currently projected for the late 2020s.[39]

Implementation will provide C/A code to ensure backward compatibility
Assured of 1.5 dB increase in minimum C/A code power to mitigate any noise floor increase
Non-data signal component contains a pilot carrier to improve tracking
Enables greater civil interoperability with Galileo L1"

The entire article is available here:
https://en.wikipedia.org/wiki/GPS_Block_III

It isn't clear whether the L1C signal, which ensures backward compatibility, will be a permanent part of GPS III or will it go away when the system is fully operational.

I find it hard to believe the government will render millions of GPS enabled devices obsolete with the flick of a switch.

It also isn't clear what advantages L1C on GPS III will have over the existing GPSII system. Clearly, it will not be as robust as the military version.

I expect backward compatibility to mean what is usually does--the old stuff will still work, but won't get some of the benefits available to newer kit.

In particular, better accuracy stemming from better ionospheric correction enabled by the use of more than one frequency obviously can't be obtained by legacy receivers which only receive on one frequency.

On the other hand, higher downlink power will clearly give some help in certain marginal reception conditions. (and may, however, also give a bit more multipath error trouble in other conditions).

I think for the typical civilian user reading this site, this whole transition will be substantially a non-event.

...that a software update will take care of this problem.

No one has said "...the government will render millions of GPS enabled devices obsolete with the flick of a switch." But what is being said is that the capability of the new GPS III system, accuracy down to 1 meter for instance, may not be available to older systems. GPS III will use three new signals in addition to the current signal for a total of four civilian use signals. You can read the details of the signals at https://www.gps.gov/systems/gps/modernization/civilsignals/.

Someone has speculated "Could be that a software update will take care of this problem." I doubt that will be the case. I suspect the low level GPS receiver circuitry in Garmin devices do not have a sophisticated level on being tuned to new frequencies by software. Rather the marketing geniuses will get hold of things and develop new products.

for the improved accuracy? By that I am asking if there is a need for it that will cause existing GPS users to replace their devices with new ones just because of the better accuracy.

Personally, I have not noticed an accuracy problem with my TomTom 620, let alone a large enough problem to justify replacing it just to obtain better accuracy. I can see where other hypothetical improvements might make a replacement attractive to me, but improved accuracy by itself would just not do it - for me.

- Tom -

Assuming the three fold accuracy increase provided by GPSIII becomes a reality for consumer grade GPSr's, I can see it as a plus for handheld devices. Such devices can not rely on the "snap to" feature automotive GPSr's use to follow a road. Accuracy is far more important when used for wilderness or off road navigation.

Marine GPS receivers will be better able to navigate narrow channels with the improved accuracy.

Automotive devices could also benefit when driving in areas where there are two or more roads in close proximity to each other.

It is likely the additional signal strength of GPSIII satellites will benefit both old and new receivers to some extent in poor reception areas.

For most consumers, to some degree, the law of diminishing returns comes into play as far as accuracy is concerned. There is nothing to be gained when the GPS receiver is more accurate than the map being used to navigate.

Many questions remain as to the actual benefits of GPSIII for consumer grade equipment. For general automotive use, IMO, these benefits will be minimal and probably not worth the substantial investment in a new GPSr.

From the article linked below:

"...For civilian users, the new GPS satellites will be compatible with other systems, including the EU’s Galileo system..."

https://hackaday.com/2018/12/18/gps-iii-launching-today-but-...

when we say more accurate, that implies what we have is inaccurate. Is this somehow when one doesn't live in a metro area?

From my own travels, the avg. person cannot even relate to miles per gallon, miles per hour, etc. When I was a little kid, I asked my dad what options were (stock). He said it was a game invented by some big boys on Wall Street, because simply buying and selling and having cash was too simple. This GPSIII sounds like options. I remember as a kid having trouble understanding what shorting a stock meant. But as an adult, few can comprehend that the amount one can lose shorting a stock is an infinite number. Heck, many don't know what zero or infinity even are lol