Author Topic: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?  (Read 10739 times)

WhiteHare

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #45 on: February 05, 2016, 03:26:58 PM »
Since no one had any specific part recommendations,  :(, I went ahead and ordered the choke and 7 different EMI filters that I linked at the beginning of the thread.  I probably didn't do a good job spec'ing or choosing them, so it's very nearly a shot in the dark.  Be that as it may, now that I'm able to read ambient RSSI on the RFM69 all the way down to -127, I'll try them out as best I can and see if any of them yield noticeable improvement when running from a DC voltage source that's mains powered and with other possible interferers on the same circuit.  I also have a rig I can use for testing purposes to insert components between the radio module and the atmega328p and other board components to test the choke and filters for effect if used in that way.
« Last Edit: February 05, 2016, 06:46:43 PM by WhiteHare »

joelucid

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #46 on: February 11, 2016, 11:31:59 AM »
Hey WhiteHare,

interesting investigations - I'm just now catching up on all the RSSI posts of yours. Did you already get a chance to try the parts you ordered?

I still like the idea of a esp8266/moteino board as simple install server and internet gateway. But your numbers looked like I'd have to expect a significant RSSI degradation. Not quite as bad as it is periodically with the Pi. But I would consider an impact of -12 or so pretty significant. Esp. now that I'm putting a few TH Motes based on the lower power RFM69CW together.

Joe

WhiteHare

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #47 on: February 11, 2016, 12:26:35 PM »
Did you already get a chance to try the parts you ordered?


Not yet.  The choke turned out to be so tiny I'm not sure yet how I'm even going to solder it.  If I put it on a breakout board, I'm afraid it may undermine its effectiveness.  I may have to shelve them until someday, when I learn how to make my own PCB's.  Unfortunately, I don't think "someday" will be soon!
« Last Edit: February 11, 2016, 12:34:04 PM by WhiteHare »

Felix

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #48 on: February 12, 2016, 02:32:51 PM »
Sorry if this is totally random, but I think it has some value with respect to the overall topic:


perky

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #49 on: February 12, 2016, 06:04:07 PM »
A little simplified, but OK for basic understanding. This is mainly about cross coupling and EMI within a circuit, we're also concerned with how this gets coupled onto the power supply wires, and what happens where the signals enter or exit a box. For that minimising common mode noise is very important. The Handbook of Black Magic should be in all engineers' libraries  ;)
Mark.

Felix

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Re: Best way to isolate/mitigate conducted EMI affecting an RFM69 Moteino?
« Reply #50 on: February 17, 2016, 04:27:12 PM »
Another video about EMI in relation to signal integrity:

https://embed-ssl.wistia.com/deliveries/c8dde81c580b65be8538587acc77ddc999443ee8/file.mp4

More of these videos here, (DesignCon 2014 by Eric Bogatin).