There could be external reasons for false readings, are there any overhead power cables nearby or are you near any military buildings or any radio/tv or local ham radio antennae, are you near an airport with ground level radar, any nearby electrically powered railway lines? Any of this kind of thing could cause problems either directly or by amplifying the noise.
I mean... there are a lot of potential EMI/RFI sources but I'm not sure how most people will identify them or the magnitude of the interference caused by each. There is not much homeowners can really do about them and these are all very common/essential in any major city. For my location:
- All the power distribution in my subdivision is underground.
- 3-phase overhead circuits are on the nearest main street but the size/number of obstructions and distance is unlikely to cause such significant problems. They are medium voltage and on poles not steel transmission towers.
- No airports nearby.
- No electrical railways nearby.
- No military nearby.
- No HAM repeaters nearby. Not even sure how you can find local HAM user antennas?
- No radar nearby.
- There are radiocommunications antennae nearby. Not sure if the broadcast frequencies are public information.
As an aside, I do work on critical industrial equipment that is highly susceptible to noise and have been part of detailed EMI/RFI testing of equipment and the associated industry standards/requirements. All the care and design strategies we utilize there are essentially impossible for home owners to implement.
My testing update: I completed my testing with all the power in my home turned off. The results were interesting. With the AM radio at 530kHz, I was able to test the different areas for interference. The amount of noise on the incoming power cables from the utility do have some noise even within galvanized conduit, which isn't that surprising. Not a huge amount, but it is there.
What was most interesting is that even with all breakers isolated, one set of power cables was still radiating noise. This is because I share one wall with a neighbour. The unshielded, untwisted wires have some inductive coupling which adds noise on those particular power cables. Placing the WH57 adjacent to these cables has enough noise to trigger the LED to flicker and indicate there is a problem.
Also noted is that when my UPS perform their line-interactive self tests, the rectifiers do have bursts of EMI/RFI which is likely problematic with the WH57 sensor circuit. Those tests run on a regular basis, so something to keep in mind for all those who have UPS or multiple UPS in their home. Myself, I had suspected this may happen and had already sited my WH57 far away from them.
I also reconfirmed the interference from my powerline ethernet adapters. Even though mine are all wired to the same phase, still there are emissions to some extent on the other power circuits in my home. This makes the WH57 placement quite difficult. The good thing is that the sensor does have noise sensing capability and indication (as I previously mentioned) so you can use it to identify major noise sources. The bad thing is that the unit is so sensitive that you can still encounter a lot of trouble even if you locate the unit some distance away.
Right now my only potential solution is to locate the WH57 as far as my home as possible but still within communications range of my GW1000 and HP2551. Easier said than done because the unit does not seem like it can be directly exposed to the elements. Plus I need to make sure it does not get stolen or damaged outside somehow.
Overall: Not a very promising situation and frankly I'm a bit frustrated. At this point, I find it very difficult to recommend anybody to buy a WH57. Still open to suggestions but the newer replacement version I received directly from Ecowitt still has similar issues.
