8 November 2017

We learned about all the parameters that we need to develop the link equation.

We derived the equation for the received power and explained the meaning of free space loss.

Then we derived the link equation.

spectral density in the limit for radio waves, listed types of thermal noise and plotted the curve for sky noise as a

function of radio frequency.

We derived the equation for the system temperature. We talked about the 3K cosmic background radiation and

Penzias and Wilson who discovered it. Click here for the latest results from the Planck mission.

We learned how the equivalent noise temperature of a device can be referred to the input and then also to the output of the device. We looked at the differences between amplifiers and passive attenuators. We looked at a block diagram of a receiver and the equivalent input temperatures at different sections of the receiver. Then we used an example and went through the computation of the system temperature of the antenna and the receiver. We also found and expression for the noise power spectral density at the receiver output.

We realized what Penzias and Wilson needed to consider to conclude that there is a 3K cosmic microwave background (CMB)

radiation in the universe.

We talked about LNA's. And then we turned to the C/N ratio.

We introduced the saturation flux density, the effective aperture of an isotropic antenna and the back-off from the saturation point of a transponder amplifier which is related to the non-linearity of the amplification curve. We looked at the combined uplink and downlink C/N. Then we distinguished

between different kinds of noise, thermal noise, intermodulation noise and intrasystem interference noise and learned that the overall C/N is computed by adding the N/C's for the different kinds of noise. Then we looked at an example of a multicarrier satellite circuit at C-band and computed the overall C/N ratio.