OpenEnergyMonitor Community

emonBase aerial

I just got a new emonBase out of the box…

The lid is not fixed down. The white RF aerial is coiled inside.

Do i need to drill a hole in the lid and push the aerial through so it sticks up vertically…

Will this improve RF reception from the emonTx.

That depends on the distance between your emonBase and the nodes that will be sending data to it as well
as how many and what kind of RF obstructions are between the Base and the nodes.

If the distance involved is significant or there are RF obstructions in the path, yes.

However, if your emonBase and (say) your emonTx are near each other, i.e. only a couple of metres apart and there aren’t any RF obstructions in the path between them, it won’t make much difference.

Thanks for a prompt reply, my emonTx is at the front of the house in the portch. The emonBase is 5m away with a staircase (wood) and probably 1 non suporting internal wall (brick) in between.

I can try the aerial in or out but as there is no real indication as to which will be better i may have to guess.

Are your graphs showing data dropouts? If not, you’re likely OK and nothing needs to be changed.
(don’t fix it if it aint broke!*)

There is a way to view the received signal strength. I haven’t run emonCMS for about four years, so how to
go about it escapes me ATM. @Robert.Wall, can you assist?

Indeed - it should appear on the Setup → Inputs page as “rssi”, at the bottom of the block of data coming from the emonTx. The value is decibels below a reference level, so a less negative number is better. Anything above about -70 should give very few failures. I see -25 from an emonTH about 8 ft across the garage from my emonPi - you don’t expect to see that through a wall.

Thanks RW! thumbsup

I was confused by this when I got my emonbase too. :roll_eyes:

As Robert says, you can see the RSSI levels that are logged and you can check data drop outs by unchecking the missing data check box in the graphs.

It’s easy to test the effect of simply uncoiling the wire and making it roughly vertical. Replacing the lid with a hole drilled in it can follow later. Another tip that was suggested to solve my problems was to add a ground plane underneath the box (a piece of aluminium foil). I tried that but didn’t use it in the end, but moving the emonbase unit about a few inches can definitely make a difference. In my case, finding a different place to park my car was the ah-ha solution!

Both those comments apply equally to either or both ends of the link. If there’s a standing wave, remember the antenna is ¼ wavelength long, and ½ a wavelength is the distance between the deepest null and highest peak.

Somewhat easier to slip a piece of foil under an emonbase than try to position foil under the antenna on a wall-mounted emonTx though :grinning:

edit: I fitted a dipole antenna to the emonTx eventually.