Added comment to constants.

applications/lofar2/libraries/sdp/src/vhdl/sdp_pkg.vhd

@@ -77,7 +77,7 @@ PACKAGE sdp_pkg is
   CONSTANT c_sdp_N_sub                     : NATURAL := 512;
   CONSTANT c_sdp_N_sync_rcu                : NATURAL := 1;
   CONSTANT c_sdp_N_taps                    : NATURAL := 16;
-  CONSTANT c_sdp_P_sq                      : NATURAL := 9;
+  CONSTANT c_sdp_P_sq                      : NATURAL := 9;   -- = N_pn / 2 + 1
   CONSTANT c_sdp_Q_fft                     : NATURAL := 2;
   CONSTANT c_sdp_S_pn                      : NATURAL := 12;
   CONSTANT c_sdp_S_rcu                     : NATURAL := 3;
@@ -115,10 +115,10 @@ PACKAGE sdp_pkg is
   CONSTANT c_sdp_N_sync_jesd        : NATURAL := c_sdp_S_pn * c_sdp_N_sync_rcu / c_sdp_S_rcu; -- = 4, nof JESD IP sync outputs per PN
   CONSTANT c_sdp_A_pn               : NATURAL := c_sdp_S_pn / c_sdp_N_pol;  -- = 6 dual pol antenna per PN, is 6 signal input pairs
   CONSTANT c_sdp_P_pfb              : NATURAL := c_sdp_S_pn / c_sdp_Q_fft;  -- = 6 PFB units, for 6 signal input pairs
-  CONSTANT c_sdp_T_adc              : TIME    := (10**6 / c_sdp_f_adc_MHz) * 1 ps;
-  CONSTANT c_sdp_T_sub              : TIME    := c_sdp_N_fft * c_sdp_T_adc;
+  CONSTANT c_sdp_T_adc              : TIME    := (10**6 / c_sdp_f_adc_MHz) * 1 ps;  -- = 5 ns @ 200MHz
+  CONSTANT c_sdp_T_sub              : TIME    := c_sdp_N_fft * c_sdp_T_adc;  -- = 5.12 us @ 200MHz
   CONSTANT c_sdp_W_bf_product       : NATURAL := c_sdp_W_subband + c_sdp_W_bf_weight -1;
-  CONSTANT c_sdp_X_sq               : NATURAL := c_sdp_S_pn * c_sdp_S_pn;
+  CONSTANT c_sdp_X_sq               : NATURAL := c_sdp_S_pn * c_sdp_S_pn;  -- = 144
   CONSTANT c_sdp_block_period       : NATURAL := c_sdp_N_fft * 1000 / c_sdp_f_adc_MHz;  -- = 5120 [ns]
   CONSTANT c_sdp_N_beamlets_sdp     : NATURAL := c_sdp_N_beamsets * c_sdp_S_sub_bf;  -- = 976
   CONSTANT c_sdp_unit_sub_weight    : NATURAL := 2**c_sdp_W_sub_weight_fraction;  -- 2**13, so range +-4.0 for 16 bit signed weight