===== Noise Implementation =====

This section contains all stuff related to AC Noise calculation in Gnucap.

Currently (April 2011) noise is implemented in experimental branch and work as plugin. Please see [[Code-related Stuff]] for more details.

=== Noise calculations basics ===

Noise is claculated using adjacent system method 
[TBD GS - complete, explain ]

=== Noise Simulation Syntax ===

To run noise simulation - ad the following line to circuit file (spice format):

''.noise V(a,b) Dev stepmode points fromF toF''


  * V(a,b)  - output to measure noise at - nodes a to b; possible form:
V(a) is the same as V(a,0)
  * Dev    - device which is considered as input
  * stepmode - [o{ctave}, d{ecade}, lin, ti{mes}, step, by, +, *] 
  * points - number of points (depends on stepmode)
  * fromF   - lowest frequency
  * toF     - highest frequency

It will calculate noise power density between output nodes "a" and "b" and equivalent power at input device "Dev" using "stepmode" making "points" in frequency range "fromF"-"toF"

Example:

'' .noise v(3) V1 oct 5 10 10K ''

 - calcualate spectral noise density at node "3" and reduce it to input device V1 making 5 points per octave in frequency range from 10HZ to 10KHZ 

'' .noise V(10,12) I1 dec 2 10K 10MEG''

 - calcualate spectral noise density between nodes 10 and 12 and reduce it to input device I1 making 2 points per decade in frequency range from 10KHZ to 10MHZ 


== Output ==


Usually simulators also support ''.print noise'' statement. Now it is not implemented yet. 
Currently output contains:

'' Freq inoise_density onoise_density ''

Also - at the end of the frequency range total power over the range s integrated:

'' inoise_total onoise_total ''


=== Code related stuff ===

Currently noise simulation is implemented as plugin which is available at github at the following [[ https://github.com/gserdyuk/gnucap-plugins | link ]]

It re-uses s_ac.cc file (ac simulation) to implement noise analysis.

At the present moment (April 2011) noise works with only [[https://github.com/gserdyuk/gnucap-a | gnucap-a]] branch of gnucap, but hopefully soon it will work with main trunk too. 

[TBD - make description of the noise code]


  * [[Discussions]] regarding noise implementation