With the insights from part 1 it is clear that we need a circuit which can produce the modulated signal: s(t)=Accos(2πfct)⋅(1+km(t)) After some searching and consideration I found the AD633 from Analog Devices which is an analogue multiplier with differential inputs which does the following: From the figure one can see that it basically performs…
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Bringing back the early days of radio, part 1: Background and thinking
I posses a number of very old radio receivers from the beginning of the last century – truly beautiful artefacts from the dawn of wireless communication and I have restored them all to working condition, see below. These old receivers were mainly built to receive radio broadcasts on very low frequencies, i.e. Long Wave or…
Reviving ancient computer equipment and software – genesis
As a young engineering mind I read and dreamt about computers during my childhood in the 70’s. I had my first hands-on computer experience with a Sinclair ZX81 which I borrowed from a friend during the fall of 1981. The computer only had 1kB of RAM which I soon found to be a bit limiting….