Added comment on expected DB output size in terms of M9k and M144k block RAM.

applications/apertif/designs/apertif_unb1_correlator/src/vhdl/node_apertif_unb1_correlator_output.vhd

@@ -89,6 +89,12 @@ ARCHITECTURE str OF node_apertif_unb1_correlator_output IS
   SIGNAL src_out_arr                                 : t_dp_sosi_arr(0 DOWNTO 0);
   
   -- Output DB
+  -- . In simulation store: all visibility packets for entire sync interval to avoid need to use DB arm mode.
+  -- . On hardware store
+  --   - assume use 8b instead of 9b for M9k and M144k RAM, so effectively M8k and M128k RAM
+  --   - at least 1 visibility packet to have minimal DB RAM resources of 621 * 32 b which fits in 4 M9K = 4 * 1024 * 8b
+  --   - all 64 visibility packets per beamlets to have faster M&C access and DB RAM resources 39 * 1024 * 32 b = 1277952b,
+  --     which fits in 10 M144k, because 10 * 16 * 1024 * 8b = 40 * 1024 * 32 b
   CONSTANT c_vis_header_size                         : NATURAL := 21;  -- (pad(2) + eth(14) + ip(20) + udp(8) + app_id(16) + app_flags(24)) / 4 = 84 bytes / 4 = 21 words
   CONSTANT c_vis_payload_size                        : NATURAL := c_nof_complex*g_nof_visibilities;
   CONSTANT c_vis_packet_size                         : NATURAL := c_vis_header_size + c_vis_payload_size;  -- = 21 + 600 = 621