From c9035441581c78396dddd488d9649d74bdf52fba Mon Sep 17 00:00:00 2001
From: c vw <dl1ycf@darc.de>
Date: Fri, 28 Feb 2020 10:59:13 +0100
Subject: [PATCH] Re-normalized TX panadapter for PS feedback signal
---
old_protocol.c | 8 ++++----
transmitter.c | 28 ++++++++++++++++++++++++++--
2 files changed, 30 insertions(+), 6 deletions(-)
diff --git a/old_protocol.c b/old_protocol.c
index 44e1680..82fc028 100644
--- a/old_protocol.c
+++ b/old_protocol.c
@@ -1286,10 +1286,10 @@ static int last_power=0;
}
}
-if(last_power!=power) {
- g_print("power=%d\n",power);
- last_power=power;
-}
+//if(last_power!=power) {
+// g_print("power=%d\n",power);
+// last_power=power;
+//}
diff --git a/transmitter.c b/transmitter.c
index f709b84..3444b95 100644
--- a/transmitter.c
+++ b/transmitter.c
@@ -407,8 +407,32 @@ static gboolean update_display(gpointer data) {
int start = (full-width) /2; // Copy from start ... (end-1)
float *tfp=tx->pixel_samples;
float *rfp=rx_feedback->pixel_samples+start;
- // if full == width, then we just copy all samples
- memcpy(tfp, rfp, width*sizeof(float));
+ int i;
+ //
+ // The TX panadapter shows a RELATIVE signal strength. A CW or single-tone signal at
+ // full drive appears at 0dBm, the two peaks of a full-drive two-tone signal appear
+ // at -6 dBm each. THIS DOES NOT DEPEND ON THE POSITION OF THE DRIVE LEVEL SLIDER.
+ // The strength of the feedback signal, however, depends on the drive, on the PA and
+ // on the attenuation effective in the feedback path.
+ // We try to normalize the feeback signal such that is looks like a "normal" TX
+ // panadapter if the feedback is optimal for PURESIGNAL (that is, if the attenuation
+ // is optimal). The correction depends on the protocol (different peak levels in the TX
+ // feedback channel, old=0.407, new=0.2899, difference is 3 dB).
+ switch (protocol) {
+ case ORIGINAL_PROTOCOL:
+ for (i=0; i<width; i++) {
+ *tfp++ =*rfp++ + 12.0;
+ }
+ break;
+ case NEW_PROTOCOL:
+ for (i=0; i<width; i++) {
+ *tfp++ =*rfp++ + 15.0;
+ }
+ break;
+ default:
+ memcpy(tfp, rfp, width*sizeof(float));
+ break;
+ }
g_mutex_unlock(&rx_feedback->mutex);
} else {
#endif
--
2.45.2