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vis_noise

PURPOSE ^

noise=vis_noise(Tsys,tau,bw,A,eff)

SYNOPSIS ^

function noise=vis_noise(Tsys,tau,bw,A,eff)

DESCRIPTION ^

 noise=vis_noise(Tsys,tau,bw,A,eff)

 Calc E rms uncertainty of a complex visibility due to thermal noise.
 Output in Jy.
 This is sqrt(2)*sigma in eqn 6.51 of Ref TMS page 189.
 The uncertainty in the real or complex part is this
 times 1/sqrt(2) (see eqn 6.50).
 Note that the rms map noise is E/sqrt(2*n_b) where n_b is the number
 of baselines (see eqn 6.62)

 Tsys - system temperature
 tau  - integration time in seconds
 bw   - bandwidth in Hertz
 A    - Antenna area
 eff  - efficiency factor (correlator and/or aperture)

 eg:
 vis_noise(30,140*10*13*60,1e9,pi*0.1^2,0.8)*randnc(size(u))

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function noise=vis_noise(Tsys,tau,bw,A,eff)
0002 % noise=vis_noise(Tsys,tau,bw,A,eff)
0003 %
0004 % Calc E rms uncertainty of a complex visibility due to thermal noise.
0005 % Output in Jy.
0006 % This is sqrt(2)*sigma in eqn 6.51 of Ref TMS page 189.
0007 % The uncertainty in the real or complex part is this
0008 % times 1/sqrt(2) (see eqn 6.50).
0009 % Note that the rms map noise is E/sqrt(2*n_b) where n_b is the number
0010 % of baselines (see eqn 6.62)
0011 %
0012 % Tsys - system temperature
0013 % tau  - integration time in seconds
0014 % bw   - bandwidth in Hertz
0015 % A    - Antenna area
0016 % eff  - efficiency factor (correlator and/or aperture)
0017 %
0018 % eg:
0019 % vis_noise(30,140*10*13*60,1e9,pi*0.1^2,0.8)*randnc(size(u))
0020 
0021 noise=1e26*2*1.38e-23*Tsys./(sqrt(bw.*tau).*A.*eff);

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