You can lead a horse to water... Then there's hams like this: https://g3rbj.co.uk/
On Wed, Nov 4, 2020 at 12:04 PM Kristoff <krist...@skypro.be> wrote: > Don, > > > A small (slightly) remark about this video, and about hams. > > When I gave my first video-presentation for the Belgian SDR Meetup (in > September), I have a presentation on GR (an example of an RTTY decoder). > But, to keep the presentation on topic, I first posted a "list of > interesting things to view so you can better understand the > presentation" (the video you mentioned, three of the videos by Michael > Ossmann, ...). > > When I asked the audience during the presentation who had taken the time > to actually do this, I did not get any positive answers. > > You know,, ...last time when we did a workshop in a hackerspace on a > certain topic and asked the people to do some preparation, I think that > more then 3/4 did do that. > The same when I organise a workshop at work. > > > Yeah ... Hams .. (sigh) :-( > > > > 73 > kristoff - ON1ARF > > > On 4/11/2020 15:22, Don Wade wrote: > > Here’s a YouTube video that’s got a bit of pencil math (so it doesn’t > > drone on) and oscilloscopes (for the ham guys), so it’s got a bit for > > everyone . > > > > > https://m.youtube.com/watch?list=PLvOgjCaG0WzDAF1Um894vv95mrcyortOB&v=h_7d-m1ehoY > > > >> On Nov 4, 2020, at 7:52 AM, Kristoff <krist...@skypro.be> wrote: > >> > >> Jef, > >> > >> > >> Concerning the term "slope". Well, I also have my doubts about it. I > >> think that for a lot of people, this would create the assumption that > >> the signal then goes from the 'i' value to the 'q' value in a > >> straight line, which is -as we know- not the case. > >> > >> Sometimes it helps to -at first- give a very basic mental image of > >> something, and -at the end, when people understand the topic- > >> "correct" that image with a more correct one, or just point them to > >> some youtube video that explains the topic in more detail. > >> > >> > >> Anycase,this is indeed all an interesting exercise in braking down > >> concepts into very small steps. > >> > >> The amateur-radio community is a bit strange as most people do have a > >> technical background, but for a large number of hams, that is mainly > >> based on assumptions or "that's what they said in the ham-radio > >> courses", without understanding the full technical details, > >> especially topics that are highly based on math. > >> For most hams, "SDR" is just "that piece of software you install on > >> your computer to look at waterfall graphs". > >> > >> So we have a very long way to go. :-) > >> > >> > >> 73 > >> kristoff - ON1ARF > >> > >> > >> > >> On 4/11/2020 02:21, Jeff Long wrote: > >>> It's more important to give people some mental picture than to make > >>> sure it's completely correct. But, I would not use the "slope" > >>> terminology. The important things are, as you've said, (1) with the > >>> complex type, you can have a signal at baseband that is not > >>> symmetric, and (2) the price for this is doubling the amount of data > >>> needed. The signal you deal with at baseband is the same signal that > >>> is seen centered on the RF carrier. > >>> > >>> I don't see a great way to talk about "phase" without going into the > >>> math. It is important to get into "phase" when you talk about any > >>> modulation fancier than slow FSK. > >>> > >>> Good luck. Hope you find the right balance between useful, > >>> digestible, and correct. > >>> > >>> On Tue, Nov 3, 2020 at 7:20 PM David Hagood <david.hag...@gmail.com > >>> <mailto:david.hag...@gmail.com>> wrote: > >>> > >>> I am sorrowful that you have decided you are going to stick with an > >>> explanation that is fundamentally incorrect. I know how direct > >>> conversion systems work - I design the software for them for a > >>> living. > >>> What you are basing your mental model on is an optimization for > >>> the case > >>> where the system is both sub-sampling the signal and going digital > in > >>> the same operation. However, in many extremely high sample rate > >>> systems, > >>> the signal is brought down to baseband by mixing it with analog > >>> quadrature signals - that's the place where I and Q come from - and > I > >>> assure you the only "delay by 90 degrees" is in the creation of the > >>> quadrature LO signals, not in the sampling of the actual data. But > >>> I've > >>> been around the Sun enough times to know that since you have decided > >>> upon this course and don't seem to want to change, there's no > >>> point in > >>> continuing to try to help. > >>> > >>> > >> > >> > > -- K1FZY (WA4TPW) SK 9/29/37-4/13/15
