Hello! I'm DVdm. Your recent edit(s) to the page Relativistic Doppler effect appear to have added incorrect information, so they have been reverted for now. If you believe the information you added was correct, please cite a reliable source or discuss your change on the article's talk page. If you would like to experiment, please use your sandbox. If you think I made a mistake, or if you have any questions, you can leave me a message on my talk page. Thank you. - DVdm ( talk) 23:37, 24 May 2024 (UTC) reply

Note: on pages XI-32 and XI-33 of ref 5 of Morin ( https://web.archive.org/web/20180404002006/http://www.people.fas.harvard.edu/~djmorin/chap11.pdf), they are indeed moving toward each other, but they get that f > f' (received frequency is larger than emitted source frequency). In our article we get the opposite: f_r < f_s so they are moving away from each other. - DVdm ( talk) 23:50, 24 May 2024 (UTC) reply