- Muchas notas - Fran Acién

20220906 - Remote sensing - Imaging issues

Two types:

  • Reciprocating: Rotate in both directions
  • Rotating: Only rotate in one direction

Line scanning

0e72d9a920919bd97a08bbd5cf3203e5.png

Reciprocating:

  • [-] Very difficult motion
  • [-] Varying incidence angle
  • [+] Always pointing to the swath
  • [-] Does never point into space (calibration)
  • [-] Integration time not constant

Rotating:

  • [+] Free time to calibrate
  • [+] Better motion
  • [+] Time wasted looking into space (calibration)
  • [+] Well suited for TPR (Total power radiometer)

Conical scanning

Reciprocating

d7b2527079ef0f47144ec5b1a27213ce.png

Rotating

27143bda13f97f3c19ddcfb37317c6dd.png

Reciprocating:

  • Almost constant incidence angle
  • Difficult motion Rotating:
  • Better motion
  • still some time wasted
  • well suited for TPR

Push-broom

2eff55647540af4275e46ff19083144d.png

  • Long integration times
  • More complex system, more expensive, more power, etc.
  • Redundancy
  • No motion
  • No time wasted
  • Well suited for NIR

Antenna beamwidth is not a well defined term, the best way is to say -3dB angle.

$$ \text{Antenna beamwidth} = \theta \approx 1.4 \frac{\lambda}{D} = \frac{\text{Wavelength}}{\text{Aperture}} $$ FP = Foot print

¿How the foot print affect to different parameters? ¿What happen is FP is getting shorter?

6611842e088988b53319e04f8e13d9d1.png

\(\Delta T\) refers to integration time per pixel.

Soil moisture (SM):

$$ T_B(f, \theta, SM, \text{crop density}, \text{soil type}, \text{polarization}) $$

Ocean salinity, Sea Surface Salinity (SSS)

$$ T_B(f, \theta, SS \ \text{salinity}, SS \ \text{temperature}, \text{wind speed}) $$