The total noise of the system contains molecular absorption noise, antenna noise temperature
, system noise temperature
The overall system noise temperature
is therefore suboptimal due to the insertionloss of the waveguide connection and passive elements at room temperature.
A known hot and cold temperature noise source is applied to the input of the DUT, and the noise results at the output are compared to determine noise temperature
of the DUT itself.
to receive dependences of a Bit-Error Rate (BER) on a free space path loss, a phase/frequency offsets, a satellite transponder high power amplifiers back-off level, antennas diameter, a phase noise, a noise temperature
, and a bit rate;
Recent improvements to the H Line feed and LNA arrangements have yielded a system noise temperature
of about 56K.
Convolutional coding considerably decreases probability of errors and a BER is vanishing for free space path loss in the range from 0 dB to 161 dB (in case of very low noise temperature
, 20 K) and from 0 dB to 155 dB (in case of typical noise temperature
, 290 K).
It is necessary to consider the secondary lobes of the antenna which sense, although in a reduced manner, the temperature of all surrounding objects, the noise temperature
of the front end of the receiver, the low efficiency of the antenna and its "dilution effect" that occurs when the surface of the hot body to be measured is smaller than the area of the primary beam of the antenna.
By contrast, the noise temperature
of the researchers' solid-state maser is already a few hundred mK.
Combining (6) with (5), the antenna noise temperature
can be related with the output radiometer voltage:
Meanwhile, the noise power can be characterized by an equivalent noise temperature
in radiometry .
in an environment with an external noise temperature
of 290 K, use of
Rather than concentrating on theory, practitioner Maas emphasizes real-world circuit performance, giving some background on phase and amplitude noise as well as linear and nonlinear noise, then progressing to noise and random processes, including narrowband random processes, noise figure, noise temperature
, and the system noise model, the noise theory of solid-state devices and of linear and nonlinear circuits, low-noise amplifiers, oscillators, and mixers and frequency multipliers.