Category: Receivers

High performance 144MHz transverter design workup – noise and gain analysis

A correspondent is designing a high performance transverter from 144MHz to 28MHz to be used with a Elecraft K3 transceiver.

A question that arises is just how good should the performance of the transverter be, what Noise Figure and Gain should it have without having performance that cannot be fully realised due to external noise. Continue reading High performance 144MHz transverter design workup – noise and gain analysis

Last update: 26th February, 2017, 10:45 AM

Using an attenuator for NoiseLo/NoiseHi in NFM

A common method of making Noise Figure measurements of a receiver is to use a noise generator of known noise power. The output power of the DUT is measured with the generator off (NoiseLo) and on (NoiseHi), a Y factor calculated, and from that Noise Figure is calculated.

Continue reading Using an attenuator for NoiseLo/NoiseHi in NFM

Last update: 6th March, 2014, 3:43 PM

Designing high performance VHF/UHF receive systems – Part 7

Summary

This series of seven articles has:

  • explained the meaning and value of G/T as a single metric for receive system performance;
  • defined and explained the G and T terms;
  • explained the relationship between Teq and Noise Figure;
  • explained how to analyse simple cascaded stages and hence more complex networks;
  • described how to estimate transceiver Noise Figure and Teq;
  • demonstrated application of the analysis techniques to a set of practical configuration options to provided quantitative comparison of the S/N performance of the options; and
  • discussed measurement of G/T as a means of validating system performance.

Continue reading Designing high performance VHF/UHF receive systems – Part 7

Last update: 19th June, 2014, 10:00 PM

Designing high performance VHF/UHF receive systems – Part 6

Measurement of G/T

G/T can be measured using celestial noise sources provided the antenna can be pointed to them. The noise source that is most appropriate will depend on expected G/T, frequency, time etc.

Sun

Continue reading Designing high performance VHF/UHF receive systems – Part 6

Last update: 19th June, 2014, 10:00 PM

Designing high performance VHF/UHF receive systems – Part 5

Bringing it all together

This part explains how to build a model of the entire receive system to calculate G/T.

Firstly, make an inventory of all of the system elements that you intend to model.

A model needs to be no more detailed than is necessary to provide adequate accuracy for the purpose at hand.

Continue reading Designing high performance VHF/UHF receive systems – Part 5

Last update: 19th June, 2014, 10:01 PM