private void AddOffset()
        {
            frmOffset    dialog = new frmOffset(frmOffset.Mode.Add);
            DialogResult r      = dialog.ShowDialog();

            if (r == DialogResult.OK)
            {
                // Add the offset to the listview (lsvOffsets)

                // Create new variable to hold phase and amplitude values
                PhaseAmplitudeOffset newValue = new PhaseAmplitudeOffset
                {
                    Phase     = dialog.getPhase(),
                    Amplitude = dialog.getAmp()
                };

                // create new listview item to store phase/amp values and add to list
                ListViewItem newItem;
                string[]     arr = new string[2];
                arr[0]  = newValue.Phase.ToString();
                arr[1]  = newValue.Amplitude.ToString();
                newItem = new ListViewItem(arr);
                lsvOffsets.Items.Add(newItem);
            }
        }