5. Subroutines needed

The following is based on HP code, but there is some guesswork here as I don't really know just how SYPARM will work, what calls to it are like, or what commands can be sent to STEER and what data can be obtained from STEER.

• Input file reader
• Input parameter parser
• Syparm reader
• Telescope configurator
• Receiver configurator
• Instrument configurator
• System Temperature Calibration using noise diode and LO
• Counts per Kelvin Calibration using noise diode
• Convert input parameters to scan parameters
• Coordinate transformations
• PMOD Returns a value of angle in PMOD, -180.0 < PMOD < 180.0
• HALIM Returns east or west hour angle limits
• Telescope driver
• Instrument output and telescope coordinates reader
• Data binning
• Data scaling
• Plot data on screen annotated with key parameters
• Write housekeeping and data to file
• Write log file

5.1 System Temperature Calibration subroutine

// standard calibration routine for absolute total power mode:

// usually just two polarizations, but
// note that with a polarimeter there could be four counters to read

inputs: counter_to_read[Ncounters]
        noise diode to fire
        local oscillator for receiver
        ND_in_Kelvins_for_this_output[Ncounters]
        Nsamples 
outputs: Tsys[Ncounters]
        Tsys_err[Ncounters]
        CperK[Ncounters]
        CperK_err[Ncounters]
        NDerror[Ncounters]
        LOerror[Ncounters]
        output[Ncounters][Nsets]Nsamples]       

// three sets samples are taken
Nsets = 3

// initialise the outputs
for (ic = 0 ; ic < Ncounters ; ic++ ) do
        {
        COerror[ic] = 0 /* counter problem */
        NDerror[ic] = 0 /* noise diode problem */
        LOerror[ic] = 0 /* local oscillator problem */
        CperK[ic] = 0   /* counts per Kelvin per counter */
        CperK_err[ic] = 0 /* uncertainty in CperK per counter */
        Tsys[ic] = 0    /* System temperature per counter */
        Tsys_err[ic] = 0  /* uncertainty in Tsys per counter */
        for ( is = 0 ; is < Nsets ; is++ ) do
                {
                for ( i = 0 ; i < Nsamples ; i++ ) do
                        { output[ic][is][i] = 0 }
                }
        }

// obtain three sets of data
for ( is = 0 ; is < Nsets ; is++ ) do 
        {
        if ( is = 0 ) then { turn off local oscillator,
                            turn off noise diode }
        if ( is = 1 ) then { turn on local oscillator,
                            turn on noise diode }
        if ( is = 2 ) then { turn off noise diode }

        pause to let output settle

        ask all counters in use for Nsamples of output

        check for errors reading counters
        
        // get mean and rms for all good counters (ic) and each sample (i)
        for ( ic = 0 ; ic <= Ncounters ; ic++ ) do
                {
                sum[ic] = 0
                sum_sqd[ic] = 0
                for ( i = 0 ; i <= Nsamples ; i++ ) do 
                        {
                        sum[ic] = sum[ic] + output[ic][is][i]
                        sum_sqd[ic] = sum_sqd[ic] + output[ic][is][i]**2
                        }
                mean[ic][i] = sum[ic] / Nsamples
                rms[ic][i] = sqrt ((sum_sqd[ic] - sum[ic]**2/Nsamples) 
                          / (Nsamples - 1)
                }
        }

// now we have all the data, lets see what we can calculate from it
// for each good counter:
for ( ic = 0 ; ic <= Ncounters ; ic++ ) do
        {
        // check that the noise diode fired (ND > 6 x RMS noise):
        if ((mean[ic][2] - mean[ic][3]) < 3*(rms[ic][2]+rms[ic][3])) then 
                { NDerror[ic] = 1 }

        // check that the local oscillator switched off:
        if ((mean[ic][3] - mean[ic][1] < 3*(rms[ic][3]+rms[ic][1])) then 
                { LOerror[ic] = 1 }

        // calculate the counts per Kelvin and error:
        if ( NDerror[ic] = 0 ) then 
                {
                CperK[ic] = (mean[ic][3] - mean[ic][2]) / ND_in_Kelvins[ic]

                CperK_err[ic] = sqrt (rms[ic][3]**2 + rms[ic][2]**2) 
                                / ND_in_Kelvins[ic]
                }

        // calculate the system temperature and error:
        if ( NDerror[ic] = 0 && LOerror[ic] = 0) then 
                {
                Tsys[ic] = (mean[ic][3] - mean[ic][1]) 
                           / (mean[ic][2] - mean[ic][3]) 
                           * ND_in_Kelvins[ic]

                Tsys_err[ic] = Tsys[ic] * sqrt ((
                                 (rms[ic][3]**2 + rms[ic][1]**2) / 
                                 (mean[ic][3] - mean[ic][1])**2) +
                                ((rms[ic][2]**2 + rms[ic][3]**2) /
                                 (mean[ic][2] - mean[ic][3]**2))
                }
        }