Difference between revisions of "EMI"
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| + | See also [[Filters]] | ||
| + | |||
| + | ==List== | ||
| + | * https://www.eevblog.com/forum/projects/what-fcc-certification-test-that-i-need-to-pass-for-project-that-i-am-working-on/ - links to | ||
| + | * https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-15/subpart-C - Has a list of 'not allowed' RF frequencies. | ||
| + | * https://www.eevblog.com/forum/projects/impact-on-emi-due-to-test-points-placed-on-bottom-side-of-pcb/ - Concern about test points going through a 4 layer board to the unshielded bottom (top is shielded). | ||
| + | |||
| + | ==Tips/Techniques== | ||
===Spectrum Depends Upon Frequency and Rise/Fall Time=== | ===Spectrum Depends Upon Frequency and Rise/Fall Time=== | ||
Per hackaday: https://hackaday.com/2024/03/30/how-much-bandwidth-does-cw-really-occupy/ and https://www.youtube.com/watch?v=KEgrTwjWLf0 | Per hackaday: https://hackaday.com/2024/03/30/how-much-bandwidth-does-cw-really-occupy/ and https://www.youtube.com/watch?v=KEgrTwjWLf0 | ||
Ideally a spectrum analyzer will look at both the spectrum and the waveform (oscilloscope), the latter being used for rise/fall time. Also worth noting is the old adage about square waves being made up of sine waves. http://web.archive.org/web/20230711194015/https://www.thepulsar.be/article/generating-sine-wave-from-square-waves/ Of course, rise and fall time is often the highest frequency in your circuit. CW is a type of OOK (on off keying), which he refers to as an extreme example of AM modulation (interesting) often catalogued with FSK (frequency shift keying) where different frequencies take the 1 and 0. OOK is the simplest transceiver and used with the cheap 433 or 900MHz transceivers on ebay which I have played around with but ended up just purchasing some low power labs tx (which ended up not working properly...) | Ideally a spectrum analyzer will look at both the spectrum and the waveform (oscilloscope), the latter being used for rise/fall time. Also worth noting is the old adage about square waves being made up of sine waves. http://web.archive.org/web/20230711194015/https://www.thepulsar.be/article/generating-sine-wave-from-square-waves/ Of course, rise and fall time is often the highest frequency in your circuit. CW is a type of OOK (on off keying), which he refers to as an extreme example of AM modulation (interesting) often catalogued with FSK (frequency shift keying) where different frequencies take the 1 and 0. OOK is the simplest transceiver and used with the cheap 433 or 900MHz transceivers on ebay which I have played around with but ended up just purchasing some low power labs tx (which ended up not working properly...) | ||
| + | |||
| + | ==Links== | ||
| + | * https://www.sigidwiki.com/wiki/Signal_Identification_Guide | ||
| + | * https://wiki.gnuradio.org/index.php/Main_Page | ||
| + | |||
[[Category:online notes]] | [[Category:online notes]] | ||
Latest revision as of 23:06, 24 October 2024
See also Filters
List
- https://www.eevblog.com/forum/projects/what-fcc-certification-test-that-i-need-to-pass-for-project-that-i-am-working-on/ - links to
- https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-15/subpart-C - Has a list of 'not allowed' RF frequencies.
- https://www.eevblog.com/forum/projects/impact-on-emi-due-to-test-points-placed-on-bottom-side-of-pcb/ - Concern about test points going through a 4 layer board to the unshielded bottom (top is shielded).
Tips/Techniques
Spectrum Depends Upon Frequency and Rise/Fall Time
Per hackaday: https://hackaday.com/2024/03/30/how-much-bandwidth-does-cw-really-occupy/ and https://www.youtube.com/watch?v=KEgrTwjWLf0 Ideally a spectrum analyzer will look at both the spectrum and the waveform (oscilloscope), the latter being used for rise/fall time. Also worth noting is the old adage about square waves being made up of sine waves. http://web.archive.org/web/20230711194015/https://www.thepulsar.be/article/generating-sine-wave-from-square-waves/ Of course, rise and fall time is often the highest frequency in your circuit. CW is a type of OOK (on off keying), which he refers to as an extreme example of AM modulation (interesting) often catalogued with FSK (frequency shift keying) where different frequencies take the 1 and 0. OOK is the simplest transceiver and used with the cheap 433 or 900MHz transceivers on ebay which I have played around with but ended up just purchasing some low power labs tx (which ended up not working properly...)
