In message <[email protected]>, dated Tue, 1 Sep 2009, Ralph McDiarmid <[email protected]> writes:
>I am correct to recall that it is impossible to identify whether a >carrier with sidebands is AM or FM by just looking at the spectrum? Only in a very special case: if the modulation index (deviation/modulating frequency) is 1. FM is very rarely used with such a low modulation index; a minimum value of 5 (75 kHz/15 kHz) is typical, and then the FM signal has a broad spectrum, of which about 250 kHz needs to be preserved in order not to distort the modulation too much (attenuation of the higher order sidebands really does introduce non-linearity distortion of the modulation). -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
