Questions about Cell Strength vs Quality Boron BRN402 vs BRN404

Connectivity Cellular
1

Hello,

Our customer is delivering units to their end customers and in some cases we are seeing low cell signal strength (CSS) or low cell signal quality (CSQ). I have no idea of the physical location of the installations.
Can anyone provide any information about the difference between cell signal strength and cell quality? Obviously we would like them all to close to 100% but how likely is that?
When we bring units online and do testing at our factory, in many cases I see a lot of the devices connect to AT&T. If I recall if the unit connected to AT&T, the CSS and CSQ were often in the 50% range. I have also seen some devices connect to T-Mobile (at our factory) and these seem to have CSS and CSQ in the upper 80% range.
Why is it that some devices connect to ATT and some to T-Mobile? I know in the field the devices will probably try to latch onto the strongest signal possible.

I know I can grab the CSS and CSQ via the vitals and I have recorded a handful and plan to monitor this over time.
Does anyone have any suggestions or know if the device has the ability to capture the CSS and CSQ on the device and log it? I thought it would be interesting to have the units log this info over a period of time and then dump it to see how they are performing.

With some of the units deployed in the field, I can see that the CSS and CSQ for a handful of devices the values are around 80 or higher. Most other devices are between 30 and 70%. Some are down in the low 20%.
For most part a lot of the devices currently in the field are BRN402 units running DeviceOS 3.0.0. We are now starting to ship BRN404X units on 4.0.2.
The question I am getting from the customer is, is there any room to improve the RF performance? I am no RF expert so I am rely on just how the devices operate. For all the testing I have performed, the devices seem to just work. Now that devices are being scattered all over, the units show lower CSS and CSQ has the customer concerned.
If we are seeing units that have CSS and CSQ in the upper 80 range does this mean, the design is mostly OK? There are so many things that can influence the RF performance that I am not sure how to accurately determine the over RF performance.

If anyone has any wisdom or knowledge to share, I would love to learn more.

2

You probably have the wrong antenna like I do. Boron BRN402 vs BRN404 setup issues

I was able to get mine to connect, but the signal is not as good as the 402. If I get the 'correct' antenna in I will let you know if it's any better.

3

I am using the antenna that was recommended by Particle.

BRN404X Antenna
PARANTC41EA

BRN402/BRN404 Antenna
Taoglas FXUB63.07.0150C

5

I received the proper antennas for the 404s today.

I did a side-by-side comparison.

402 running 4.0.1 OS
404 running 4.1.0 OS.

402 were tested 3 times with the last vitals refresh button. The values were always stable no matter how many times I refreshed the vitals on all these tests.

image

404 was tested 3 times with the last vitals refresh button.

image

I swapped their locations, which were only 12 inches apart, power cycled them, and retested them again 3 times each.

402

image

404

image

Looks like the 404s are just not as strong. Not sure why this is.

I run another test in the same position where I swapped their antennas (put the 404 ant on 402 and 402 ant on 404).

402

image

404 never connected just blinks green (the signal in that position is very low and the reason I discovered I had the wrong antenna for the 404).

I run another test in the same position with the correct antennas on the chips, but only one at a time without the other unit powered on.

402
image

404
just blinks green and never connects.

I'm a little concerned the signal strength is this different 402 to 404. The 402s are being depreciated right? So 404s will be the only option?

1 Like
6

You may want to check out: https://opencellid.org/

From what I can tell, they are connecting to different cell towers so signal strength/quality is not an apples to apples comparison. Now you are probably wondering why would they connect to different cell towers. Someone from Particle May have to dig into the Device IDs to figure out why they don’t connect to the same cell tower.

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