AGO ELF/VLF Narrowband Channel Calibration

The digital output for the ELF/VLF narrowband channels can be converted into physical units of Volts/meter by applying the following formula:

where the constants A and B are determined by the antenna size and the gains at each stage of the system.  More details are available on the derivation of the calibration formula.

Given a specific station, channel and date, the constants A and B can be determined by the following piece of psuedocode:
 

function [A, B] = agoVLFcalibration( STATION, CHANNEL, DATE );     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  % Returns the calibration factors for the ELF/VLF experiment %  % E_w = A*DigitalOutput + B; [V/m]                           %  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   if ( SITE == 1 )       date1 = datenum('21-Nov-1996');       date2 = datenum('09-Dec-1997');   elseif ( SITE == 2 )       date1 = datenum('12-Nov-1996');       date2 = datenum('25-Nov-1997');   elseif ( SITE == 3 )       date1 = datenum('08-Dec-1996');       date2 = datenum('17-Dec-1997');   elseif ( SITE == 4 )       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%       % DATA FROM 08-Jan-1998 TO 18-DEC-1998        %       % CHANNELS 9, 10, 11, 12, 13, 14, 15, 20      %       % IS INVALID - ANTENNA WAS DISCONNECTED AT P4 %       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%       date1 = datenum('15-Dec-1996');       date2 = datenum('08-Jan-1998');   elseif ( SITE == 5 )       date1 = datenum('27-Dec-1996');       date2 = datenum('27-Nov-1998');   end;   %%%%%%%%%%%%   % Antennas %   %%%%%%%%%%%%   % Calibration Constant Antenna 1 (1.70 m)^2, 11 turns   ant1 = 0.944;   % Calibration Constant Antenna 2 (4.88 m)^2, 6 turns   ant2 = 0.210;   if ( DATE <= date1 )       C_ant = ant1;       G_1 = 20;       G_bb = 35;       if ( CHANNEL >= 9 & CHANNEL <= 12 )       % Hiss Filter Type I           G_2 = 20;           G_rf = 10;           G_if = 0;       elseif ( CHANNEL >= 13 & CHANNEL <= 15 )       % TVLF Filter           G_2 = -10;           G_rf = 20;           G_if = 15;       end;  elseif ( DATE <= date2 )       C_ant = ant1;       G_1 = 30;       G_bb = 35;       if ( CHANNEL >= 9 & CHANNEL <= 12 )       % Hiss Filter Type I           G_2 = 20;           G_rf = 10;           G_if = 0;       elseif ( CHANNEL >= 13 & CHANNEL <= 15 )       % TVLF Filter           G_2 = -10;           G_rf = 20;           G_if = 15;       end;   else      if ( CHANNEL == 9 | CHANNEL == 12 | CHANNEL == 13 | CHANNEL == 14 )       % Hiss Filter Type II, N/S           C_ant = ant2;           G_1 = 20;           G_bb = 30;           G_2 = 0;           G_rf = 20;           G_if = 0;       elseif ( CHANNEL == 10 | CHANNEL == 11 | CHANNEL == 15 )       % Hiss Filter Type I, N/S           C_ant = ant2;           G_1 = 20;           G_bb = 30;           G_2 = 20;           G_rf = 10;           G_if = 0;       elseif ( CHANNEL == 19 )       % Hiss Filter Type I, E/W           C_ant = ant1;           G_1 = 30;           G_bb = 35;           G_2 = 20;           G_rf = 10;           G_if = 0;       elseif ( CHANNEL == 20 )       % TVLF Filter, N/S           C_ant = ant2;           G_1 = 20;           G_bb = 30;           G_2 = -10;           G_rf = 20;           G_if = 15;       end;   end;   W = 2047;   X = 0.00488;   Y = 10;   Z = 2.3;   G_t = G_1 + G_bb + G_2 + G_rf + G_if;   A = X*C_ant/Z*10^(-G_t/20);   B = (Y-X*W)*C_ant/Z*10^(-G_t/20);