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    Re: GPS AntiSpoof and integrating sextants?
    From: Tony Oz
    Date: 2021 Jan 22, 01:02 -0800

    Dear David,

    The ИАС-1(М) is a clone of this well known SOLD KM2 instrument.

    The name translates as the "Integrating Sextant for Aviation", the "М" index denotes the "Modified" model. The difference between the  ИАС-1 and the ИАС-1М is:

    • the mechanical "flag" appearing over the bubble chamber when the intergation interval runs out
    • the bubble level is slightly different - a bigger air chamber (a small cylinder popping up from the AH body) is introduced, apparently - to prevent AH damage or leakage if the bubble left small after the sight was taken (to counter the thermal expansion of the liquid)
    • several minor details of not so big significance

    The "-3" sextant was for marine use, its' proper name is "ИМС-3", which translates as the "Integrating Sextant for Marine". It is said to be the further enhancement of its' aviation "brothers". I plan to buy that as well, the one obvious enhancement is the handle. The ИМС-3 has the left handle as per the Fig.2 (ref the "SOLD" article), while both the ИАС-1 and ИАС-1М have left handle similar to the one on the drum side (ref Fig.3).

    All those sextants are featuring the integrators running for 40, 120 or 200 seconds.

    I wish the GPS AntiSpoof could accommodate for that.

    Warm regards,
    60°N 30°E

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