Added calc_max_nsub script

meerpipe/calc_max_nsub.py

@@ -0,0 +1,52 @@
+import math
+import numpy as np
+
+def calc_max_nsub(
+        sn,
+        nchan,
+        duration,
+        input_nsub,
+        sn_desired=12.,
+        minimum_duration=480.,
+    ):
+    """
+    Calculate the maximum number of time subintegrations of sensitive ToAs for an archive.
+
+    Parameters
+    ----------
+    sn : float
+        The signal-to-noise ratio of the archive.
+    nchan : int
+        The number of frequency channels in the decimated archive.
+    duration : float
+        The duration of the archive in seconds.
+    input_nsub : int
+        The number of subintegrations of the input archive.
+    sn_desired : float
+        The desired signal-to-noise ratio (default: 12.).
+    minimum_duration : float
+        The minimum duration of the archive in seconds (default: 480.).
+
+    Returns
+    -------
+    nsub : int
+        The estimated number of subintegrations that will create the maximum number of sensitive ToAs.
+    """
+    # Calc estimated sn when channelised
+    sn_chan = sn / np.sqrt(nchan)
+
+    # Calc duration estimate to get desired sn
+    estimated_duration = duration * ( sn_desired / sn_chan ) **2
+
+    if estimated_duration < minimum_duration:
+        # estimated duration is less than minimum so us minimum
+        estimated_duration = minimum_duration
+
+    # Work out nsub using math.floor to round down
+    nsub = math.floor( duration / estimated_duration )
+
+    if nsub > input_nsub:
+        # nsub is greater than input so use input
+        nsub = input_nsub
+
+    return nsub

meerpipe/scripts/calc_max_nsub.py

@@ -0,0 +1,60 @@
+import argparse
+
+from meerpipe.calc_max_nsub import calc_max_nsub
+
+def main():
+    parser = argparse.ArgumentParser(description="Calculate maximum number of time subintegratons of sensitive ToAs for an archive")
+    parser.add_argument(
+        "--sn",
+        type=float,
+        required=True
+        help="The signal-to-noise ratio of the archive",
+    )
+    parser.add_argument(
+        "--nchan",
+        type=int,
+        required=True
+        help="The number of frequency channels in the decimated archive",
+    )
+    parser.add_argument(
+        "--duration",
+        type=float,
+        required=True
+        help="The duration of the archive in seconds",
+    )
+    parser.add_argument(
+        "--input_nsub",
+        type=float,
+        required=True
+        help="The number of subintegrations of the input archive",
+    )
+    parser.add_argument(
+        "--sn_desired",
+        type=float,
+        default=12.,
+        help="The desired signal-to-noise ratio (default: 12.)",
+    )
+    parser.add_argument(
+        "--minimum_duration",
+        type=float,
+        default=480.,
+        help="The minimum duration of the archive in seconds (default: 480.)",
+    )
+    args = parser.parse_args()
+
+    nsub = calc_max_nsub(
+        sn,
+        nchan,
+        duration,
+        input_nsub,
+        sn_desired=12.,
+        minimum_duration=480,
+    )
+    if nsub = 1:
+        print("1")
+    else:
+        print(f"1 {nsub}")
+
+
+if __name__ == '__main__':
+    main()