EM Spectrum analysis of solo?

[pious_greek]

This might be an exercise in futility, but figured I'd attempt to learn something... Has anybody, or is anybody on the forum able to perform a spectral analysis of solo's electromagnetics?

I'm trying to determine the attenuation needed over solo's problematic frequency range for proper GPS shielding.

 

[Dogman1973]

This might be an exercise in futility, but figured I'd attempt to learn something... Has anybody, or is anybody on the forum able to perform a spectral analysis of solo's electromagnetics?

I'm trying to determine the attenuation needed over solo's problematic frequency range for proper GPS shielding.

Are you talking about the radiated emissions? Thats a bit difficult to measure, and even then, there's not much you can do about it beyond the existing shielding. (unless we were to move the gps)
GPS is operating at 1.2 & 1.5GHz... which also means we're out of hobbyist/consumer range equipment :-(
Although if anyone does have access to the right gear I'd love to see some results too!

I'm actually more interested in the conducted noise coming from the ESC's. The motor pods do seem to have some basic filtering, but I've got some chokes and caps I might throw at them and see if it helps.

 

[pious_greek]

Was hoping to tackle the radiative noise first before I try to wrap my head around the conductive noise sources. I want to explore some alternative polymer shields with better attenuation properties than the copper or V2.

I've read that 20 picofarad caps attenuate well at GPS L1 frequencies, and sometimes mixing various caps, yields greater attenuation range, but I got the impression that trying to filter conductive noise could exacerbate the problem as well if they weren't properly placed on the board or properly sized...

I'll try to upload some photos tonight, but I've seen some ESC boards with caps soldered across some of the input pins...

 

[Pedals2Paddles]

I believe the majority of RFI that interferes with the GPS comes from the GoPro. Many different action cameras have this problem. My Mobius does the same thing.

 

[pious_greek]

Dogman, here's some show and tell of various ESC versions... I think the E-2 is the latest and greatest and what shipped with Solo. The first picture here shows what i think is a cap hand soldered across the pin. The other shows some variations in population of what I assume are caps?

...

 

[Dogman1973]

Dogman, here's some show and tell of various ESC versions... I think the E-2 is the latest and greatest and what shipped with Solo. The first picture here shows what i think is a cap hand soldered across the pin. The other shows some variations in population of what I assume are caps?

View attachment 4967View attachment 4968 View attachment 4969 ...

Yeah those are SMD Capacitors (the brown ones).... would be small (in the picofarad range) so it would seem they were added for high frequency suppression.

When I get some time I'll do some testing by adding electrolytics as well... a bit more cant hurt. Maybe some ferrite chokes.
I only have gear to measure up to 40MHz, so cant really test the effect of the SMD caps.

I havent checked, but does the uBlox software have any diagnostics that would atleast indicate SNR or noise floor? Maybe thats a crude way to see any difference?

Also I'm not sure how much impact load (on motors) would have on the noise... that'll be difficult to simulate on the ground