Fix usrp2 tvrx so that it tunes monotonically.

Use same (nasty) tactic used on usrp1.  Get "free" inversion by lying
about real value of 2nd IF.

diff --git a/usrp2/firmware/lib/db_tvrx.c b/usrp2/firmware/lib/db_tvrx.c
index 490ea69e84c97a6eb60f4341a8d2af1279db9f7e..f38bba8f15ecd6cb9dd70e9cf565d643073c30e3 100644 (file)
--- a/usrp2/firmware/lib/db_tvrx.c
+++ b/usrp2/firmware/lib/db_tvrx.c
@@ -113,7 +113,7 @@ struct db_tvrx2 db_tvrx2 = {
   .base.gain_step_size = U2_DOUBLE_TO_FXPT_GAIN(1),
   .base.is_quadrature = false,
   .base.i_and_q_swapped = false,
-  .base.spectrum_inverted = true,
+  .base.spectrum_inverted = false,
   .base.default_lo_offset = U2_DOUBLE_TO_FXPT_FREQ(0),
   .base.init = tvrx_init,
   .base.set_freq = tvrx_set_freq,
@@ -125,7 +125,7 @@ struct db_tvrx2 db_tvrx2 = {
   // .base.atr_tx_delay =
   // .base.atr_rx_delay =
   .common.first_if = U2_DOUBLE_TO_FXPT_FREQ(44e6),
-  .common.second_if = U2_DOUBLE_TO_FXPT_FREQ(44e6),
+  .common.second_if = U2_DOUBLE_TO_FXPT_FREQ(56e6),    // Fs - 44e6
 };
 
 struct db_tvrx3 db_tvrx3 = {
@@ -140,7 +140,7 @@ struct db_tvrx3 db_tvrx3 = {
   .base.gain_step_size = U2_DOUBLE_TO_FXPT_GAIN(1),
   .base.is_quadrature = false,
   .base.i_and_q_swapped = false,
-  .base.spectrum_inverted = true,
+  .base.spectrum_inverted = false,
   .base.default_lo_offset = U2_DOUBLE_TO_FXPT_FREQ(0),
   .base.init = tvrx_init,
   .base.set_freq = tvrx_set_freq,
@@ -152,7 +152,7 @@ struct db_tvrx3 db_tvrx3 = {
   // .base.atr_tx_delay =
   // .base.atr_rx_delay =
   .common.first_if = U2_DOUBLE_TO_FXPT_FREQ(44e6),
-  .common.second_if = U2_DOUBLE_TO_FXPT_FREQ(44e6),
+  .common.second_if = U2_DOUBLE_TO_FXPT_FREQ(56e6),    // Fs - 44e6
 };
 
 bool