F7: Is "MULTI-FREQUENCY POSITIONING" dual band or is it not?

Didn’t think of that, I’m sure polarized sunglasses are gonna be fun! I picked up sapphire due to scratch resistance due to occupation

I read again Garmin site and it's strange, that this MULTI-FREQUENCY POSITIONING item is not on previous models. So it shouldn't mean combination of GPS systems. Maybe this is really L1+L5 dual band and they measured battery consumption with multi band only on top models. But this is my assumption. We will see it, when somebody has F7 in hands.

I will upgrade my F6XSapphire with the F7XSapphire only if test will shows that there's a lot of precision encreasing on the 7x with this new feature...

What I find strange is that even Ray, probably the best sports tech reviewer doesn't know about what miltiband means. Sadly, we are not close to a full constelation of I think Block 3 GPS SV's that support the L5 frequency. It would be good to know if Fenix uses the same Chinese and European GNSS additional frequencies.

"

Q: Why did Garmin not have multi-band frequencies in their devices before? Why now?

A: The U.S. Air Force (now specifically the Space Force) maintains the satellite constellation. Eventually satellites fail and need to be replaced. Rather than launching a satellite directly after a failure, the Air Force keeps active spares in reserves, which helps them maintain a full constellation even during satellite failures. Eventually, older generation satellites fail and are moved to a final orbit and newer satellites take their place. So even though L5 satellites started launching in 2009, it took many years to add satellites to the constellation. Gradually as the new modernized satellites were added, they began to show their impact. Even today some GPS satellites don’t broadcast L5 and will need to be upgraded once they complete their life. In March 2021, about 52% of GPS satellites had L5. By 2023, we expect about 71% to have L5 (but that of course depends on the Space Force).

Q: What benefit does multi-band give to the user regarding GPS accuracy?

A: The main benefit of using a handheld with multi-band frequency is in areas where GPS signals can be received but are severely degraded. In these cases, the receiver has to sort out what are reflections and what are direct line-of-sight signals. In positioning, reflected signals lead to inaccurate distances to the satellite. When these inaccurate distances are used, the position can jump, veer off course or just not make any sense because they don’t agree with each other. In these cases, L5 will provide more continuity and accuracy than with a traditional L1 device. Of course, there are no silver bullets with GPS, and the signal won’t always work in any environment, but in general this will be a welcome improvement. 

Q: When might someone want to use a multi-band handheld?

A: When accuracy really matters, L5 is a needed feature. There is also another benefit rarely talked about, and that’s called reliability. Reliability is the mathematical confidence in the accuracy numbers the receiver is telling you. Accuracy is generally thought of as the error from the true point. However, if the receiver knew the exact error from the true point, it would just give you the true point. Instead the receiver uses the measurement consistency to indicate how accurate the position is. The consistency between measurements is what indicates the reliability. If all the measurements agree, then you can generally think that you have a reliable and trustworthy solution. If the measurements don’t really agree, then you may not be very confident about the accuracy metric. Generally, there is a trade-off in accuracy and reliability. To get more reliability (or confidence), you generally have to give a less accurate indicator. All of this doesn’t change the coordinates the receiver is computing — just the receiver’s confidence about those coordinates. 

Take for example an airplane traveling across the ocean. The receiver’s estimated accuracy could be three meters, but the more important aspect is how reliable that three-meter number is. In aviation it’s often more important to be confident in the solution than accurate. Thus, if the confidence is low and thus somewhat risky to use, the pilot can use an alternative navigation source. If the confidence is high, the pilot can decide if the accuracy they have is sufficient for their mission (landing or navigating through airspaces, etc.).

With multi-band, you have more information, which generally leads to more confidence in the solution. This way you can trust your solution more than you would have previously."

The Block IIF also transmits L5 signals. So 12 (IIF) + 4 (III) sats transmit L5 signal at the moment (the 5th Block III sat is launched ~6months ago but still not active... they need too long time somewhy, usually after launch it needs apprx 1 month or sometimes even less to set it active), that always give You 3-4  sats (or more) with L5 signal for sure. The Galileo has no full constellation yet (but it is almost complete), only the Beidou has full.

https://youtu.be/rKYXq04-QEs

What is Multi-Band GNSS and Why Should You Care About It?

https://youtu.be/hwgdGk50gK8