So I have an emonTx installed and connected to my emonBase. It has an optical pulse sensor on the solar generation meter, a 100 A CT on the cable from that meter and uses a 9V AC voltage reference. The meter has conventional 1 Wh flashes. I can see various inputs on my emoncms installation: power1,…

So your wire whip is ~ 83 mm? That is the length for 868 MHz. I’d suggest you replace it - and while you’re at it, just check that you have the correct RFM69 - check the appearance here.

Never mind. Red herring. It is 165 mm when it’s actually stretched out.

A ground plane will work at either end, or both ends. If one Tx is weak, that’s the candidate for a ground plane. That whip is one quarter wavelength, so moving something by that distance represents a long way, if there’s some cancellation going on due to reflections.

[image] djh: So I unwound the wire antenna in the emonBase and now the signal seems reliable (rssi around -71 - -72). Good result. Coiling the antenna is a compromise at best. Coiled up, the antenna is far from the desired quarter-wavelength. The placement of the ground plane isn’t overly cr…

Using a ground plane at the transmitter is more difficult, since it’s wall-mounted. I looked at the video and believe I understand what it’s showing. I suspect in my case the isolated ‘ground’ plane (i.e. sheet of foil) is also coupling to my nearby Wi-Fi router and increasing the noise seen by the…

[image] djh: There’s also something called rssi that I don’t understand (it’s value is -33). An RSSI of -33 is good. Very good, actually. That being the case, you should be good to go, as is. The receiver sensitivity extends well past an RSSI of -90. At -33, you’re in good shape.

-33 is the value for my first emonTx, which is about a metre from the emonBase. My problem is with my second emonTx, which is 40 m or so away, and that’s what the discussion has been about. I’m getting a lot of dropouts (unusably many) at around -80 indicated. Though it seems to be mostly working a…

In that case, forget the ground plane at the emonBase, and look to having a ground plane, or if that’s not possible, a dipole (I think that was mentioned in the thread about ground planes) at the problematical transmitter.

[image] djh: I’ve got some dipoles on order; I’ll let you all know how they work after they arrive. The dipoles just arrived and I fitted one to the remote emonTx. The RSSI has gone from -71 ~ -75 to -62 ~ -64 so that’s a very good result. I probably won’t fit a dipole to the emonBase at pres…

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