add argument check for device handle

also outputs all text to stderr
implement rate and frequency read functions

1 files changed, 2 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 8232428..c6ec80a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -113,6 +113,8 @@ int main(int argc, char **argv)
 	r = rtlsdr_set_center_freq(dev, frequency);
 	if (r < 0)
 		fprintf(stderr, "WARNING: Failed to set center freq.\n");
+	else
+		fprintf(stderr, "Tuned to %i Hz.\n", frequency);
 
 	file = fopen(filename, "wb");