Originally our 5GHz ePMP APs shipped with AXN_1.51_2801 GPS firmware, which we then updated to AXN_1.51_2838. Those radios, and newer 5Ghz and 2.4GHz APs that shipped with 2838 pre-installed currently indicate that they are running the newest version.
Now we have some new 5Ghz APs that have GPS firmware AXN_3.20_8174 on them, and they indicate THAT is the newest version.
Are they different GPS chips? I'm trying to figure out why there's such a drastic difference in numbering, and why both are claimed to be current.
Also, possibly related, I wanted to pass along that I had one on the bench yesterday (8174) that was seeing 12 satellites, tracking 7, providing reliable sync. Without any GPS antenna, inside a cinderblock building that usually stops all but the most sentitive GPS receivers.
Originally our 5GHz ePMP APs shipped with AXN_1.51_2801 GPS firmware, which we then updated to AXN_1.51_2838. Those radios, and newer 5Ghz and 2.4GHz APs that shipped with 2838 pre-installed currently indicate that they are running the newest version.
Now we have some new 5Ghz APs that have GPS firmware AXN_3.20_8174 on them, and they indicate THAT is the newest version.
Are they different GPS chips? I'm trying to figure out why there's such a drastic difference in numbering, and why both are claimed to be current.
Also, possibly related, I wanted to pass along that I had one on the bench yesterday (8174) that was seeing 12 satellites, tracking 7, providing reliable sync. Without any GPS antenna, inside a cinderblock building that usually stops all but the most sentitive GPS receivers.
j
Hi J,
Yes, the ones showing AXN_3.20_8174 and indicating it is the latest version support GLONASS in addition to GPS. This is a different chip than the ones the previous radios were shipping with. Functionally they are no different for synchronization capabilties. Its just that the new chip can also track satellites that are part of the GLONASS system.
Its just that the new chip can also track satellites that are part of the GLONASS system.
Thanks,
Sriram
Hey Sri, can you confirm if these AP's with newer GPS chipsets can actually take advantage of 'seeing' the GLONASS satellites, and if yes, would this increase GPS lock reliablity and speed of lock on startup?
Its just that the new chip can also track satellites that are part of the GLONASS system.
Thanks,
Sriram
Hey Sri, can you confirm if these AP's with newer GPS chipsets can actually take advantage of 'seeing' the GLONASS satellites, and if yes, would this increase GPS lock reliablity and speed of lock on startup?
Hi Eric,
The speed of locking is not impacted at all due to this new chip. We have confirmed that with our testing.
In terms of reliability, it depends. We are not able to get good data on how reliable GLONASS is around the world, even from the GPS/GLONASS chip vendor. In our testing (admittedly in the Chicago area) we did have a lot of trouble getting GLONASS to lock on. At one point, we even had to use a simulator in the lab to transmit GLONASS signals to complete our testing. But then you see J above indicating he's got solid tracking inside a cinder block building. However, I don't know how many the 7 satellites that J is tracking are GPS and how many are GLONASS.
In general, when you are outdoors with clear view of the sky, GPS is reliable.
That said, with this new chip, you can mix and match GPS and GLONASS to get a 3D lock. 4 satellites need to be tracked to get a 3D lock and reliable sync. However, you need a minimum of 3 of either system to achieve this lock. For ex: The chip can achieve a 3D lock if it tracks 3 GPS + 1 GLONASS OR 1 GPS + 3 GLONASS. But it cannot get a 3d lock if it tracks 2 GPS + 2 GLONASS.
For reference, I'm located at (34.873108, -79.655570)in Hamlet NC, this building is about 5 miles north of the South Carolina border.
Radio is lying on a workbench against a southern wall of the building, cinderblock, no GPS antenna connected. Currently it can see 20 satellites, is tracking 8-10 of them. Another radio is atop a 500' tower 18 miles south of here (with external GPS antenna connected), it's tracking 18 out of 20 visible right now.
I don't remember where the ID numbers switch - I can see satellite IDs up to 88 right now on both aforementioned radios. Higher-numbered I presume are GLONASS - it's locked onto satellites 88,76,75, and 66.
