[Today’s run: 5 miles]<\/p>\n
My favorite mode of operation on my ham radio is CW, Morse Code.\u00a0 CW stands for Continuous Wave.\u00a0 As I understand it, the name was to set it apart from the earlier “spark gap” system which used large zap zap sparks, just like you would think.\u00a0 CW isn’t a zap zap, it is a single-frequency\u00a0 RF signal which is turned on and off.\u00a0 [technically, the turning on and turning off causes the signal to cover a wider range of RF frequencies.\u00a0 But a slow rate of on\/off means a very small range of frequencies covered by a single CW signal]<\/p>\n
The way our receivers work, there is a “window” of frequencies which can be heard at the same time.\u00a0 The window can be large or small depending on the receiver design.\u00a0 Noise and other signals can be heard along with the signal of interest because we hear everything within the reception window.<\/p>\n
The reception window is adjusted at multiple points within the receiver.\u00a0 You would have some sort of filtering at the antenna, at intermediate frequencies and at audio frequency right before the audio output.<\/p>\n
A guy on a mailing list advertised that he had some packets of parts for a SCAF audio filter.\u00a0 I had him send me one.\u00a0 SCAF is a switched capacitor audio filter.\u00a0 I don’t understand exactly how it works, but the descriptions I have seen make is sound like a limited range FFT-type device:\u00a0 it has analog sampling based on a clock, then the signal bins are worked through a series of steps to trim out all but the desired frequency range.<\/p>\n
I have 3-4 small CW radios which have very limited filtering.\u00a0 I hope to get this SCAF put together and use it between my radio and my headphones.<\/p>\n
Listening to a busy radio band through a sharp filter can really make a big difference.\u00a0 Signals within the window are enhanced.\u00a0 Signals outside the filter window are decreased or eliminated.<\/p>\n","protected":false},"excerpt":{"rendered":"
[Today’s run: 5 miles] My favorite mode of operation on my ham radio is CW, Morse Code.\u00a0 CW stands for Continuous Wave.\u00a0 As I understand it, the name was to set it apart from the earlier “spark gap” system which used large zap zap sparks, just like you would think.\u00a0 CW isn’t a zap zap, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-3699","post","type-post","status-publish","format-standard","hentry","category-ham-radio"],"_links":{"self":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/3699","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3699"}],"version-history":[{"count":2,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/3699\/revisions"}],"predecessor-version":[{"id":3701,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/3699\/revisions\/3701"}],"wp:attachment":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3699"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3699"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}