Define constant for DC gain of FIR filter with Coeffs16384Kaiser-quant.dat used in LOFAR1.

libraries/dsp/filter/src/vhdl/fil_pkg.vhd

@@ -61,6 +61,11 @@ package fil_pkg is
   
   constant c_fil_ppf_pipeline : t_fil_ppf_pipeline := (1, 1, 1, 1, 1, 1, 0);
   
+  -- DC gain of FIR filter with Coeffs16384Kaiser-quant.dat used in LOFAR1.
+  -- . Calculated with applications/lofar2/model/run_pfir_coef.m using application = 'lofar_subband'
+  -- . Not used in RTL, only used in test benches to verify expected subband levels
+  constant c_fil_lofar1_fir_filter_dc_gain : real := 0.994817;
+
 end package fil_pkg;
 
 package body fil_pkg is