Re: Doppler

On 02/01/2024 05:01, Daniel Estévez wrote:
> By the way,
>
> Just for fun, there is this paper about what Doppler drift rates are
> physically meaningful in RF. This topic comes up when doing de-drift
> in narrowband SETI searches:
>
> https://arxiv.org/pdf/1910.01148.pdf
>
> Some of the objects at the bottom of Table 2 do indeed exceed 10 GHz/s
> even for S-band carrier frequencies. But these are crazy situations,
> such as a transmitter orbiting a neutron star very close to its surface.
Orbiting a transmitter around a neutron star, as one does for
entertainment.  Or perhaps as a final-year project when attending
  Galactic University....


>
> Best,
> Daniel.
>
> On 01/01/2024 22:11, Marcus Müller wrote:
>> Liya,
>>
>> Doppler shift Δf is proportional to both speed and carrier frequency
>> /f/₀
>>
>> Δ/f/ = /f/₀ · /v///c/₀,
>>
>> where /v/ is the relative speed of your thing, and /c/₀ is the speed
>> of light.
>>
>> The highest frequencies we can, so far, do radio communications on,
>> are in the range of f₀=150 GHz.
>>
>> So, assuming you do communications on 150 GHz, for your Doppler shift
>> to be Δ/f=/10 GHz higher after 1s, your acceleration must been
>>
>> /a = /Δ/f / f/₀ · /c/₀ / 1s = 10 GHz / 150 GHz · 3·10⁸ m/s / s = 2/30
>> · 3·10⁸ m/s² = 1/15 /c/₀/s.
>>
>> The fastest object mankind has ever built is the Parker Solar Probe,
>> which will burn up while it spirals into the sun, at a maximum
>> velocity of ca 1/15 of the speed of light. It takes it years to reach
>> that speed, not 1s.
>>
>> So, you're assuming you're seeing a doppler from a satellite rotating
>> around earth that sees a relative acceleration higher than a
>> "satellite" around the sun actively being pulled into the sun by the
>> sun's immense gravity.
>>
>> That sadly makes no physical sense!
>>
>> Best regards,
>> Marcus
>>
>> On 01.01.24 07:51, Jiya Johnson wrote:
>>> Yes I want to use 10GHz/s
>>>
>>> On Sat, Dec 30, 2023, 4:05 PM Jiya Johnson <jiyajohnson10@gmail.com>
>>> wrote:
>>>
>>>     Greetings everyone,
>>>     https://github.com/daniestevez/reu-2023/tree/main/doppler
>>>     I went through these grc files and tried to do drift_simulation, i
>>>     am not getting the way to get 10GHz/s using inspectrum and
>>>     frequency sink slope calculation i have attached the grc and
>>>     screenshots.
>>>     image.png
>>>     image.png
>>>
>