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Improved Satellite Signal Strength


mikedx

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Things are looking up! Also check out the web link at the end.

 

Retooling the Global Positioning System

Scientific American (05/04) Vol. 290, No. 5, P. 90; Enge, Per

 

As Global Positioning System (GPS) technology currently stands, civilian users can perform geolocation to within five to 10 meters, while military users who employ more expensive equipment can track their location to within five meters--or half a meter with differential GPS (D-GPS). Civilian users are mostly restricted to the L1 frequency band, as L2 satellite signals can be disrupted by lower satellite altitudes or even minor objects. Beginning next year, GPS satellites will start to broadcast new signals (two for the military and one for civilians) designed to make GPS services even more robust and eliminate errors caused by ionospheric particles to refine geopositioning accuracy. This will be followed about three years later by additional civilian signals in the L5 frequency band--with four times as much power as current signals--emitted by more sophisticated satellites. D-GPS users will also gain advantages with multiple frequencies, and sharpen the accuracy of geopositioning to a range of 30 to 50 centimeters. GPS integrity machines will ensure the reliability of the technology by supplying real-time, legitimate error bounds. GPS transmissions will be further inoculated against radio-frequency interference through implementations such as the FAA's wide-area augmentation system, while smart antennas that can selectively direct and receive broadcasts and integration with TV and mobile phone networks are also on the way. Advanced civilian services offered by these various upgrades should benefit the farming, mining, transportation, telecommunications, electric power, mapping, and construction industries, while military gains will include automatic landings of aircraft in zero-visibility conditions.

 

http://www.sciam.com/article.cfm?chanID=sa...4F483414B7F0000

 

My apologies if this has already been covered.

Will we need software updates to our GPS's?

 

Mike

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Yes, I read the article when it first came out. I understand that all this is backwards compatible. In other words, you can use your old GPS, but you may not get 'all' the benefits of the new system untill you upgrade to a newer technology GPSr, ( which is still a ways off), to use the new multiband system. (I think)

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My wife works for a small survey company. They have recently looked into GPS survey equipment which is said to be accurate down to 1 cm.

 

Although it does use a base station to rebrodcast a corrected postion for the hand held unit. (i dont claim to know how it all works)

 

course those systems run you about $10K so....

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My wife works for a small survey company. They have recently looked into GPS survey equipment which is said to be accurate down to 1 cm.

 

Although it does use a base station to rebrodcast a corrected postion for the hand held unit. (i dont claim to know how it all works)

 

course those systems run you about $10K so....

The one my friend uses in his survey company costs 40K and they only claim a .5m-1m accuracy. 1 cm is 10 times smaller than the probe pole dia. they use.

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The first satellite with L2C (as well as L1M and L2M) isn't due for launch now until early 2005 and actually L2C will be a slightly weaker signal than L1C.

 

Today should see IIR-12 launched, all things going well since the last postponement, then there will be IIR-13 latter this year and IIR-14/M-1 will be the first of the next generation (includes L2C, L1M & l2M) sats due for launch on Feb 1 , 2005. IIR-15/M-2 will be around April 2005 and IIR-16/M-3 in June 2005 will make 3 but still not really enough to be usefull.

 

Receivers will be backward compatible as nothing is being removed just added. Not only does L2C allow atmospheric type corrections in real-time as opposed to a single frequency modelled correction but allows inproved accuracy due to different ephemeris messages, faster bit rates and forward error correction.

 

It's doubtfull that with many receivers it will be straight software upgrade unless the manufacturer has pre-planned for dual freq hardware in advance.

 

However one satellite isn't going to be enough to make L2C usefull so it will take some years to launch enough IIR-M's and IIF for the new frequency to become really usefull but every new satellite does provide a slight improvement generally.

 

The third civil freq (L5C) won't be available on the IIR-M but the following IIF's.

 

Cheers, Kerry.

Edited by Kerry.
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My wife works for a small survey company. They have recently looked into GPS survey equipment which is said to be accurate down to 1 cm.

 

Although it does use a base station to rebrodcast a corrected postion for the hand held unit. (i dont claim to know how it all works)

 

course those systems run you about $10K so....

Just a drop in the bucket for our fun!?!?!?

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