Merge pull request #183 from labomb/bias-t-support

optional bias-t support

README.md

@@ -167,3 +167,6 @@ EXTRAPACKAGES="eatmydata debhelper fakeroot"
 ALLOWUNTRUSTED="no"
 APTKEYRINGS=("/home/oliver/ppa/mutability.gpg")
 ````
+
+>**Note about Bias-t support:**
+ Bias-t support is available for RTL-SDR.com V3 dongles. If you wish to enable bias-t support, you must insure that you are building this package with a version of librtlsdr that supports this capability. You can find suitable source packages [here](https://github.com/rtlsdrblog/rtl_biast) and [here](https://github.com/librtlsdr/librtlsdr/tree/master/src). To enable the necessary support code when building, be sure to include preprocessor define macro HAVE_RTL_BIAST.

dump1090.c

@@ -371,6 +371,14 @@ int modesInitRTLSDR(void) {
     fprintf(stderr, "Gain reported by device: %.2f dB\n",
         rtlsdr_get_tuner_gain(Modes.dev)/10.0);
 
+#ifdef HAVE_RTL_BIAST
+    if (Modes.enable_rtlsdr_biast) {
+        rtlsdr_set_bias_tee(Modes.dev, 1);
+    } else {
+        rtlsdr_set_bias_tee(Modes.dev, 0);
+    }
+#endif
+
     return 0;
 }
 //
@@ -717,6 +725,9 @@ void showHelp(void) {
 "--quiet                  Disable output to stdout. Use for daemon applications\n"
 "--show-only <addr>       Show only messages from the given ICAO on stdout\n"
 "--ppm <error>            Set receiver error in parts per million (default 0)\n"
+#ifdef HAVE_RTL_BIAST
+"--enable-rtlsdr-biast    Set bias tee supply on (default off)\n"
+#endif
 "--html-dir <dir>         Use <dir> as base directory for the internal HTTP server. Defaults to " HTMLPATH "\n"
 "--write-json <dir>       Periodically write json output to <dir> (for serving by a separate webserver)\n"
 "--write-json-every <t>   Write json output every t seconds (default 1)\n"
@@ -1073,6 +1084,10 @@ int main(int argc, char **argv) {
             exit(0);
         } else if (!strcmp(argv[j],"--ppm") && more) {
             Modes.ppm_error = atoi(argv[++j]);
+#ifdef HAVE_RTL_BIAST
+        } else if (!strcmp(argv[j], "--enable-rtlsdr-biast")) {
+            Modes.enable_rtlsdr_biast = 1;
+#endif
         } else if (!strcmp(argv[j],"--quiet")) {
             Modes.quiet = 1;
         } else if (!strcmp(argv[j],"--show-only") && more) {

dump1090.h

@@ -295,6 +295,9 @@ struct {                             // Internal state
     rtlsdr_dev_t *dev;
     int           freq;
     int           ppm_error;
+#ifdef HAVE_RTL_BIAST
+    int           enable_rtlsdr_biast;
+#endif
 
     // Networking
     char           aneterr[ANET_ERR_LEN];