A human on earth. Ask me about weird tech. Bonus points if it radiates.

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  • 29 Comments
Joined 11 months ago
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Cake day: June 23rd, 2024

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  • Late reply, and forgive me if I am over-explaining. I found some random datasheets that say RG-316 has 26-29 dB per 100 ft at 1 GHz. So in the worst case, 3 ft would be 0.87 dB. Doesn’t sound like much, but 30 dBm - 0.87 dB = 29.13 dBm = 818 mW, so he is losing 182 mW to the cable. Not great, not terrible.

    It definitely should not make that much of an impact. Maybe look into antenna tuning / SWR? Or broken connectors / pinched cables? If my past IT jobs have taught me anything that that it’s always the cable, unless it’s the plug :)





  • Have you considered the Fresnel zone? You know, the ellipse between sender and receiver where most of the signal power is located? If you are 200+30 feet up, at 17.5 miles, my back of the napkin map says you are barely having a line of sight, so much of the Fresnel zone is probably obscured by the earth.

    Some random online calculator says that at 433 MHz, you have a Fresnel zone radius of 230 ft, (145 MHz has 395 ft, 866 MHz has 161 ft). So half of the signal path is blocked at 433 MHz, and apparently the rule of thumb is it should be at least 60% free. I am too lazy to do actual math right now, but that might be a reason.









  • It is much worse. I hope I am reading it wrong, but:

    The term ‘‘technology’’ […] includes […] any semiconductor, circuit board, operating system, graphics processing unit, central processing unit, tenor processing unit, field-programmable gate array, random access memory, hard drive, solid-state drive, dataflow architecture, or cloud-computing service, that is manufactured, designed, developed, supplied, deployed, completed, […] [etc.] to function artificial intelligence […] and any other hardware, software, equipment, device, component, robotic computer, processor, network […] that is manufactured, designed, developed, supplied, deployed, […] [etc.] to function artificial intelligence or generative artificial intelligence.

    This would mean that importing and exporting literally any piece of IT equipment, from a Ubuntu installer to a RAM chip, is illegal. Good luck & have fun.