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Regarding the L3 frequency
Posted by zyx on December 14, 2018 at 6:19 pmIf my rover has L1, L2 and L3 abilities and I catch a signal from an modern sattelite with all that frequencies what happens is:
1) my rover will use the three frequencies at same time;
2) my rover will use only L1 and L3.
Any of this statements are correct? Where can I found tesies, pappers about that in particular?
JerryS replied 5 years, 4 months ago 7 Members · 7 Replies- 7 Replies
The frequency is actually called ??L5? and is being brought online as a safety frequency for planes, ships, and other things. It likely depends on your software, but it should use all three. I can??t see any benefit to only using two. More frequencies = more measurements to the satellites = higher accuracy.
Depends on the quality of your receiver. An older style L1/L2 receiver may be more precise than a newer receiver built on the cheap. A precise L1/L2 position requires a receiver to use complicated algorithms to solve L1 and then solve L2. The C/A/C1 code on L1 allows a quick L1 position, the C2 code require more complicated mathematics. The new C5 code on L5 allows for a quick solution on the L5 signals. A new cheap L1/L5 reciver simply means out those two quick positions and gives a better position but all he complicated signal to signal verification is avoided. An L1/L2/L5 reciever most likely has the higher grade mathematics, correlating 1 to 2, 1 to 5 and 2 to 5 thus making a very precise position. Since the L5 signal is stronger you also may be seeing L5 only receivers in the future.
There is no single paper that covers all types of receivers, and manufacturers may be exaggerating the capabilities. First question to ask is how many channels are in the receiver and can you reallocate some to improve the performance?
More frequencies received does not improve accuracy if the frequency differences cannot be used effectively.
Paul in PA
It will depend on your hardware as much as the software. Newer gear is probably adding it but I don’t think it will be a retrofit. Replacement satellites in the last few years have been equipped with L5 but there are a lot up there that don’t have it.
.FWIW,
There is an L3 frequency. It is 1381.05 MHz and is used as part of NUDET. Not much good for navigation. You will notice that its frequency as well as L1, L2 and L5 are multiples of the fundamental frequency 10.23 MHz.
BTW, NUDET stands for nuclear detection.
Note on the summary Gavin linked to at NovAtel that all GNSS satellites are in similar frequency ranges. Also note that satellite phones are in similar ranges (Inmarsat for instance has an uplink frequency band of 1626.5 – 1660.5 MHz and the downlink frequency band is 1525.0 – 1559.0 MHz.)
Off topic to the current discussion, BUT this is why protecting that space to ground band-plan spectrum is important and why Light Squared was met with opposition. I have personally experienced loss of lock to satellites when using a GlobalStar handset within 300 feet of a GNSS receiver, sure there might be better filters and shielding that could be put in place, point is the GNSS signals are very susceptible to nearby in band interference due to their very weak signal nature. Fortunately my current Inmarsat data terminal seems to have no affect on my GNSS receivers.
SHG
Hi, guys. Thanks for all your replys.
It also matters what signals are being tracked by the base receiver/network connection the corrections are coming from. If the network or base are not capable of anything other than L1 & L2, it won’t matter what signals your rover is capable of receiving.
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