Add optional SBS RSSI field (field 23) using --devel=sbs_rssi

Adds signal level (dBFS) as an optional 23rd field in SBS/BaseStation
output. Only emitted when invoked with --devel=sbs_rssi; off by default so
existing consumers are unaffected.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

net_io.c

@@ -3560,6 +3560,15 @@ static void modesSendSBSOutput(struct modesMessage *mm, struct aircraft *a, stru
             break;
     }
 
+    if (Modes.sbs_rssi) {
+        // Field 23 is the RSSI in dBFS (if we have it)
+        if (mm->signalLevel > 0) {
+            p += sprintf(p, ",%.1f", 10.0 * log10(mm->signalLevel));
+        } else {
+            p += sprintf(p, ",");
+        }
+    }
+
     p += sprintf(p, "\r\n");
 
     completeWrite(writer, p);

readsb.c

@@ -2183,6 +2183,9 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state) {
                 if (strcasecmp(token[0], "ifile_no_synthetic") == 0) {
                     Modes.ifile_no_synthetic = 1;
                 }
+                if (strcasecmp(token[0], "sbs_rssi") == 0) {
+                    Modes.sbs_rssi = 1;
+                }
                 if (strcasecmp(token[0], "accept_synthetic") == 0) {
                     Modes.dump_accept_synthetic_now = 1;
                 }

readsb.h

@@ -770,6 +770,7 @@ struct _Modes
     int8_t dump_ignore_synthetic_now;
     int8_t syntethic_now_suppress_errors;
     int8_t ifile_no_synthetic;
+    int8_t sbs_rssi;
     int8_t tar1090_use_api;
     int8_t verbose;
 

util.c

@@ -1130,9 +1130,20 @@ void dump_beast_check(int64_t now) {
     char tstring[100];
     strftime (tstring, 100, "%H%M%S", &utc);
 
-
     char pathbuf[PATH_MAX];
-    snprintf(pathbuf, PATH_MAX, "%s/%sZ.zst", Modes.dump_beast_dir, tstring);
+
+    if (0) {
+        char datestring[20];
+        strftime(datestring, sizeof(datestring), "%Y-%m-%d", &utc);
+
+        char dirpath[PATH_MAX];
+        snprintf(dirpath, PATH_MAX, "%s/%s", Modes.dump_beast_dir, datestring);
+        mkdir(dirpath, 0755); // creates dated subdir; EEXIST is fine
+
+        snprintf(pathbuf, PATH_MAX, "%s/%sZ.zst", dirpath, tstring);
+    } else {
+        snprintf(pathbuf, PATH_MAX, "%s/%sZ.zst", Modes.dump_beast_dir, tstring);
+    }
 
     // unless we just restarted, delete the file
     if (!startup) {