Doppler Coefficient Values: BOL & EOL in SI & Kelvin

In summary, the Doppler Coefficient is a numerical value used to calculate the shift in frequency of electromagnetic waves due to the movement of a source or observer. It is measured in meters per second per Hz (m/s/Hz) in SI units and meters per second per kelvin (m/s/K) in Kelvin. The values at the beginning and end of a spacecraft's operational lifetime are important to account for changes in orbit and velocity. Doppler Coefficient values are crucial in various scientific fields and technologies for precise measurements and calculations.
  • #1
eulerpi
3
0
I know that the typical values of Doppler coefficient over core life are about -1 *10^-5 Deltak/k/°F at BOL and -1.5 * 10^-5 Deltak/k/°F at EOL.

What are the value in SI units?

Are they the same, but in Kelvin?

Thanks,
Ken
 
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  • #2
eulerpi said:
I know that the typical values of Doppler coefficient over core life are about -1 *10^-5 Deltak/k/°F at BOL and -1.5 * 10^-5 Deltak/k/°F at EOL.

What are the value in SI units?

Are they the same, but in Kelvin?

Thanks,
Ken

Ken,

Since a Celsius degree [ not degree Celsius - but Celsius degree -
the size of the interval ] is 9/5 a Fahrenheit degree - you can do the conversion.

Celsius degree = 9/5 Fahrenheit degree.

Divide by "Celsius degree":

1 = 9/5 Fahrenheit degree / Celsius degree = 1.8 F deg / C deg

Since this equals 1 - you can multiply any quantity by it without
changing the value.

If you take the BOL value of 1.0 * 10^-5 Delta k/k/F deg and multiply by
the above, and divide out the units that cancel - you get

1.8 * 10^-5 Delta k/ k / C deg = 1.8 * 10^-5 Delta k /k / Kelvin deg

the latter part is because the size of the Kelvin degree equals the size
of the Celsius degree.

Dr. Gregory Greenman
Physicist LLNL
 
  • #3
Hi Ken,

The values given in the post are in units of Deltak/k/°F, which stands for change in reactivity per change in temperature per degree Fahrenheit. To convert to SI units, we can use the following conversions:

1 Deltak = 1e-2 k (from definition of Deltak)
1 °F = 5/9 K (from conversion formula)

Therefore, the values in SI units are:
-1 * 10^-5 Deltak/k/°F = -1 * 10^-5 * 1e-2 k / (5/9 K) = -1.8 * 10^-7 k/K at BOL
-1.5 * 10^-5 Deltak/k/°F = -1.5 * 10^-5 * 1e-2 k / (5/9 K) = -2.25 * 10^-7 k/K at EOL

And yes, these values are in Kelvin since that is the SI unit for temperature. Hope this helps!
 

1. What is the Doppler Coefficient?

The Doppler Coefficient is a numerical value that represents the change in frequency of a wave as it moves relative to an observer. It is used to calculate the shift in frequency of electromagnetic waves, such as light or radio waves, due to the movement of a source or observer.

2. What is the difference between BOL and EOL in regards to Doppler Coefficient values?

BOL stands for Beginning of Life and EOL stands for End of Life. These terms refer to the start and end of the operational lifetime of a satellite or other spacecraft. The Doppler Coefficient values at BOL and EOL are used to account for any changes in the spacecraft's orbit and velocity over time, and can affect the accuracy of Doppler shift calculations.

3. How are Doppler Coefficient values measured in SI units?

In SI units, Doppler Coefficient values are measured in meters per second per Hz (m/s/Hz). This unit represents the change in velocity (m/s) for every change in frequency (Hz) of the wave.

4. How are Doppler Coefficient values measured in Kelvin?

In Kelvin, Doppler Coefficient values are measured in meters per second per kelvin (m/s/K). This unit represents the change in velocity (m/s) for every change in temperature (K) of the medium through which the wave is travelling.

5. Why are Doppler Coefficient values important in scientific research and applications?

Doppler Coefficient values are important in many scientific fields, including astronomy, meteorology, and navigation. They allow for accurate calculations of the Doppler shift, which is crucial for understanding the behavior of objects in motion and for making precise measurements of distance, speed, and temperature. Additionally, Doppler Coefficient values are used in the development and operation of satellites, spacecraft, and other technologies that rely on precise tracking and communication.

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