Late July break: ‘electric messages’ flying between two variations on summer

Senigallia rooftop satellite dish

cloudwatching, tall Highway 139 poatgutenberg@gmail.com

Pictures of satellite dish and medieval rooftops are by MIL22; of clouds above electric wires, by postgutenberg@gmail.com

 

Across the wires the electric message came

He is no better. He is much the same.

— Alfred Austin, generally reckoned to be Britain’s worst Poet Laureate of all time, on the illness of the Prince of Wales in 1871

Nothing as gossip-worthy as that is travelling between the satellite dish on a tiled roof that could easily have been built in Gutenberg’s day — and an elongated expanse of semi-wilderness an ocean and oversized continent away. We might, if we only had the time to spare, tell a shaggy bat story — a four-day saga not quite over, starring the only known species of flying mammal. Never before have we kept company with a face copied often in medieval church gargoyles — yet oddly apt for its boffin-ish style of getting about.

Read these extracts from the Wikipedia entry on echolocation, and we defy you to come away less than one hundred per cent certain that bats are the ultimate geek totem animal:

FM signal advantages

The major advantage conferred by an FM signal is extremely precise range discrimination, or localization, of the target. J.A. Simmons demonstrated this effect with a series of elegant experiments that showed how bats using FM signals could distinguish between two separate targets even when the targets were less than half a millimeter apart. This amazing ability is due to the broadband sweep of the signal, which allows for better resolution of the time delay between the call and the returning echo, thereby improving the cross correlation of the two. Additionally, if harmonic frequencies are added to the FM signal, then this localization becomes even more precise.

[…]

CF signal advantages

The structure of a CF signal is adaptive in that it allows the CF-bat to detect both the velocity of a target, and the fluttering of a target’s wings as Doppler shifted frequencies. A Doppler shift is an alteration in sound wave frequency, and is produced in two relevant situations: when the bat and its target are moving relative to each other, and when the target’s wings are oscillating back and forth. CF-bats must compensate for Doppler shifts, lowering the frequency of their call in response to echoes of elevated frequency – this ensures that the returning echo remains at the frequency to which the ears of the bat are most finely tuned. The oscillation of a target’s wings also produces amplitude shifts, which gives a CF-bat additional help in distinguishing a flying target from a stationary one.

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Senigalli rooftops JULY 2015 unnamed

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4 thoughts on “Late July break: ‘electric messages’ flying between two variations on summer

  1. I saw this post on my smartphone as I made my way home in the most dreadful traffic a little while ago (I took Oscar to the airport as his holiday was over) and I find this is one of the most romantic posts (for me) of all times the electric message the connection the strong invisible bond of then and now of the old continent and the new all can be seen in that delightful article on bats (and believe it or not my translation has a lot of Doppler in it too!)

    oh, how I treasure this all you are special!

    love Barbara

  2. Yes, I agree about the electric message and bond, link, etcetera — but when you have heard the unexpurgated bat tale, you will never mention the species in a comment containing the word ‘romantic’. Message from public health officials: (i) bites from tiny bat teeth can be invisible, so there is no way of knowing that you were bitten in your sleep; (ii) rabies symptoms can take a year to develop — but by then it’s too late. (iii) Fatality rate: 100%.

    XXX … C!

  3. Lovely! I will now look at the bats on my peepul tree with newfound respect and perhaps take the fruit off the table and close the windows.
    Love
    Shyla

  4. Dear, dear, Shyla: what a sight that must be. Can you send a pic? … Do the Authorities over there have a policy for your peepul tree squatters? Here, dear protective neighbours insist that you report mammals looping loops under your ceiling to Animal Control …where the telephone-answerer said that only the Department of Fish & Game had the resources to intervene …where a male voice announced loftily: ‘Bats? They are categorised as a pest animal. We do not deal with pests. You have to call a pest control company’ …which dispatched a shiny-eyed 27 year-old varmint-catcher, who said, ‘Oh! We aren’t allowed to kill them because they are a protected species. We have to think of other ways to get rid of them …’. Some contradiction, in the combined advice – yes?. … Do you also find that their exquisite acrobatics make up for their hideous faces?

    Hugs! — if you remember to come back and look for a reply …

    pG

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