diff --git a/main.c b/main.c
index 55c2793c..5b56905c 100644
--- a/main.c
+++ b/main.c
@@ -2271,6 +2271,8 @@ void init_adc()
 
 void read_adc_process(int sig_num)
 {
+    fprintf(stderr,"read_adc_process starting\n");
+	
     if(sig_num == SIGALRM)
     {
 // read ADC  
@@ -2289,7 +2291,7 @@ void read_adc_process(int sig_num)
 			adc_buffer[wav_position] = data[0];
 	
 			// Output data to screen
-			printf("Digital value of analog input: %d in %d us\n", data[0], micros() - time_start); // millis() - time_start);
+			fprintf(stderr, "Digital value of analog input: %d in %d us\n", data[0], micros() - time_start); // millis() - time_start);
 		}
 		    
 	        wav_position++;