Another good example would be actions Brits took in order to protect the fact that Enigma was broken. For example, when Enigma deciphering indicated that there’s warship in a specific area, they would send spotter plane first before attacking it, in order to provide enemy alternative explanation as of how they were discovered. Some operations were aborted entirely for this reason

sorry for being unclear, i forgor a word. what i meant that certain antenna designs would have specific fractional bandwidth, so that just scaling that design to higher frequency makes usable bandwidth wider in kHz terms. in order to get higher fractional bandwidth more complex or bulkier designs would be required, like thicker conductors, added parasitics, something LPDA-shaped, or maybe elaborate matching circuit, all of which cost money. i guess that while resonant amplifiers are a thing, probably bigger limitation would be bandwidth of mixer

i’d also note that antennas, amplifiers and so on have bandwidth that is some % of carrier frequency, depending on design, so just going up in frequency makes bandwidth bigger. getting higher % of bandwidth requires more sophisticated, more expensive, heavier designs. LoRa is much slower, caused by narrowed bandwidth but also because it’s more noise-resistant

but there’s separate category for “broadcast”, so it’s more of point-to-point thing?

what’s fixed service in this context?

Both got much more interesting. Also, don’t underestimate modern encryption

cyanide doesn’t accumulate, it can be broken down in some hours (very small amounts of course). otoh many heavy metals do behave this way, maybe you worked with both at the same time

all metals that bind to sulfur well are to some degree poisonous. these are lead, mercury, thallium, some platinides (in salt form), arsenic, and also copper, but less than others. some metals have other mechanisms of toxicity, like nickel, hexavalent chromium, cadmium, beryllium or barium. some of these accumulate in brain or bones, and some don’t. some are more toxic when inhaled like zinc or chromium

it’s absurdly easily detected and somewhat easily treated today, not in op’s setting

ah yeah the subtle, slow acting poison, the checks notes atropine

all of these work on nervous system which means that they act rapidly. this is worse than useless

https://en.wikipedia.org/wiki/Amanita_phalloides

you also get points for historical accuracy, as it was used as far back as ancient rome

also, how low tech is low tech? Litvinenko was dying for three weeks after polonium poisoning, and radium will have similar effects, first extracted 1898