diff --git a/applications/apertif/designs/apertif_unb1_fn_bf_emu/src/vhdl/apertif_unb1_fn_bf_emu.vhd b/applications/apertif/designs/apertif_unb1_fn_bf_emu/src/vhdl/apertif_unb1_fn_bf_emu.vhd
index 507ed1cb5c46750ff1cb21fe08cd1e96df1b91d7..8208a9e7dae5f7ae5282233a094c4d425e9beeec 100644
--- a/applications/apertif/designs/apertif_unb1_fn_bf_emu/src/vhdl/apertif_unb1_fn_bf_emu.vhd
+++ b/applications/apertif/designs/apertif_unb1_fn_bf_emu/src/vhdl/apertif_unb1_fn_bf_emu.vhd
@@ -128,7 +128,7 @@ ARCHITECTURE str OF apertif_unb1_fn_bf_emu IS
   SIGNAL pout_wdi                   : STD_LOGIC;
 
   -- Block generator
-  CONSTANT c_bg_block_size          : NATURAL := 256;
+  CONSTANT c_bg_block_size          : NATURAL := 2*64; -- 2 interleaved streams
   CONSTANT c_bg_gapsize             : NATURAL := 0;
   CONSTANT c_bg_blocks_per_sync     : NATURAL := 781250;
   CONSTANT c_bg_ctrl                : t_diag_block_gen := (sel_a_b(g_sim, '1', '0'), -- enable: On by default in simulation; MM enable required on hardware.