diff --git a/tracker/software/config.c b/tracker/software/config.c
index 3cb5c13..97687d8 100644
--- a/tracker/software/config.c
+++ b/tracker/software/config.c
@@ -355,7 +355,10 @@
 // Global variables
 #include "config.h"
 #include "aprs.h"
-#include "debug.h"
+#include "image.h"
+#include "position.h"
+#include "log.h"
+#include "chprintf.h"
 
 module_conf_t config[7];
 
@@ -363,7 +366,7 @@ uint8_t ssdv_buffer[128*1024] __attribute__((aligned(32)));	// Image buffer
 
 systime_t track_cycle_time = S2ST(60);						// Tracking cycle (all peripheral data [airpressure, GPS, temperature, ...] is collected each 60 seconds
 systime_t log_cycle_time = S2ST(600);						// Log cycle time in seconds (600 seconds)
-bool keep_cam_switched_on =	false;							// Keep camera switched on and initialized after it has been switched on once, no configuration change is possible
+bool keep_cam_switched_on =	true;							// Keep camera switched on and initialized after it has been switched on once, no configuration change is possible
 uint16_t gps_on_vbat = 3000;								// Battery voltage threshold at which GPS is switched on
 uint16_t gps_off_vbat = 2500;								// Battery voltage threshold at which GPS is switched off
 
@@ -448,7 +451,7 @@ void start_user_modules(void)
 	// Module IMAGE, APRS 2m 2GFSK
 	config[4].power = 127;									// Transmission Power
 	config[4].protocol = PROT_APRS_2GFSK;					// Protocol APRS/SSDV (2GFSK)
-	config[4].gfsk_conf.speed = 9600;						// 2GFSK Speed
+	config[4].gfsk_conf.speed = 19200;						// 2GFSK Speed
 	config[4].frequency.type = FREQ_STATIC;					// Static frequency allocation
 	config[4].frequency.hz = 144860000;						// Transmission frequency 144.860 MHz
 	config[4].trigger.type = TRIG_CONTINUOUSLY;				// Transmit continuously
diff --git a/tracker/software/config.h b/tracker/software/config.h
index a11012b..50a35ee 100644
--- a/tracker/software/config.h
+++ b/tracker/software/config.h
@@ -1,13 +1,6 @@
 #ifndef __CONFIG_H__
 #define __CONFIG_H__
 
-#include "ch.h"
-#include "hal.h"
-#include "chprintf.h"
-#include "types.h"
-#include "radio.h"
-#include "sleep.h"
-
 #define LOG_FLASH_ADDR1			0x080C0000	/* Log flash memory address 1 */
 #define LOG_FLASH_ADDR2			0x080E0000	/* Log flash memory address 2 */
 #define LOG_SECTOR_SIZE			0x20000		/* Log flash memory size */
@@ -15,9 +8,21 @@
 #define TRACE_TIME				TRUE		/* Enables time tracing on debugging port */
 #define TRACE_FILE				FALSE		/* Enables file and line tracing on debugging port */
 
-#define RUN_3V					TRUE		/* Lets the tracker run a 3V otherwise 1.8V. 3V is needed to do 20dBm radio output power.
-											 * With 1.8V only 15dBm can be done. Some serial-USB adapters also need a 3V IO level in
-											 * order to work. However 3V takes a lot of power in idle. You can save energy using 1.8V. */
+#define ACTIVATE_3V				TRUE		/* Lets the tracker run a 3V otherwise 1.8V. 3V is needed to do 20dBm radio output power
+											 * and to run USB. With 1.8V only 15dBm can be done only. Some serial-USB adapters also
+											 * need a 3V IO level in order to work. However 3V takes a lot of power in idle. You can
+											 * save energy using 1.8V. This option is activated automatically if ACTIVATE_USB is set
+											 * true. */
+
+#define ACTIVATE_USB			TRUE		/* If set to true, the USB interface will be switched on. The tracker is also switched to
+											 * 3V, because USB would not work at 1.8V. Note that the transmission power is increased
+											 * too when operating at 3V. This option will also run the STM32 at 48MHz (AHB) permanently
+											 * because USB needs that speed, otherwise it is running at 6MHz which saves a lot of power. */
+
+
+#include "ch.h"
+#include "types.h"
+#include "radio.h"
 
 void start_user_modules(void);
 
diff --git a/tracker/software/drivers/wrapper/ptime.h b/tracker/software/drivers/wrapper/ptime.h
index b8e684a..290005b 100644
--- a/tracker/software/drivers/wrapper/ptime.h
+++ b/tracker/software/drivers/wrapper/ptime.h
@@ -1,8 +1,7 @@
-#ifndef __TIME_H__
-#define __TIME_H__
+#ifndef __PTIME_H__
+#define __PTIME_H__
 
 #include "ch.h"
-#include "hal.h"
 
 typedef struct {
 	uint16_t year;
diff --git a/tracker/software/main.c b/tracker/software/main.c
index 0f12775..a592c59 100644
--- a/tracker/software/main.c
+++ b/tracker/software/main.c
@@ -27,8 +27,7 @@ int main(void) {
 	chSysInit();				// Startup RTOS
 
 	// Voltage switching (1.8V <=> 3.0V)
-	bool usbConnected = isUsbConnected();
-	if(usbConnected || RUN_3V)
+	if(ACTIVATE_USB || ACTIVATE_3V)
 	{
 		boost_voltage(true); // Ramp up voltage to 3V
 		chThdSleepMilliseconds(100);
@@ -38,11 +37,9 @@ int main(void) {
 	DEBUG_INIT();
 	TRACE_INFO("MAIN > Startup");
 
-	// Start USB (if connected)
-	if(usbConnected)
+	// Start USB
+	if(ACTIVATE_USB)
 	{
-		TRACE_INFO("MAIN > USB detected");
-
 		sduObjectInit(&SDU1);
 		sduStart(&SDU1, &serusbcfg);
 
@@ -51,8 +48,6 @@ int main(void) {
 		usbStart(serusbcfg.usbp, &usbcfg);
 		usbConnectBus(serusbcfg.usbp);
 		usb_initialized = true;
-	} else {
-		TRACE_INFO("MAIN > USB not detected");
 	}
 
 	// Startup threads
@@ -62,7 +57,7 @@ int main(void) {
 	// Print time every 10 sec
 	while(true) {
 		if (SDU1.config->usbp->state == USB_ACTIVE) {
-			thread_t *shelltp = chThdCreateFromHeap(NULL, THD_WORKING_AREA_SIZE(2048), "shell", NORMALPRIO+1, shellThread, (void*)&shell_cfg);
+			thread_t *shelltp = chThdCreateFromHeap(NULL, THD_WORKING_AREA_SIZE(512), "shell", NORMALPRIO+1, shellThread, (void*)&shell_cfg);
 			chThdWait(shelltp);
 		}
 		chThdSleepMilliseconds(1000);
diff --git a/tracker/software/mcuconf.h b/tracker/software/mcuconf.h
index 9e47470..de95b66 100644
--- a/tracker/software/mcuconf.h
+++ b/tracker/software/mcuconf.h
@@ -17,6 +17,8 @@
 #ifndef MCUCONF_H
 #define MCUCONF_H
 
+#include "config.h"
+
 /*
  * STM32F4xx drivers configuration.
  * The following settings override the default settings present in
@@ -48,7 +50,11 @@
 #define STM32_PLLN_VALUE                    192
 #define STM32_PLLP_VALUE                    4
 #define STM32_PLLQ_VALUE                    4
-#define STM32_HPRE                          STM32_HPRE_DIV2
+#if ACTIVATE_USB /* Activate 48MHz when USB is activated, otherwise 6MHz */
+#define STM32_HPRE                          STM32_HPRE_DIV1
+#else
+#define STM32_HPRE                          STM32_HPRE_DIV8
+#endif
 #define STM32_PPRE1                         STM32_PPRE1_DIV1
 #define STM32_PPRE2                         STM32_PPRE2_DIV1
 #define STM32_RTCSEL                        STM32_RTCSEL_LSI
diff --git a/tracker/software/radio.c b/tracker/software/radio.c
index 5c633a1..03e2ea8 100644
--- a/tracker/software/radio.c
+++ b/tracker/software/radio.c
@@ -1,6 +1,8 @@
 #include "ch.h"
 #include "hal.h"
+
 #include "defines.h"
+#include "tracking.h"
 #include "debug.h"
 #include "radio.h"
 #include "si4464.h"
diff --git a/tracker/software/threads/log.c b/tracker/software/threads/log.c
index 7d06e55..1a38723 100644
--- a/tracker/software/threads/log.c
+++ b/tracker/software/threads/log.c
@@ -12,6 +12,7 @@
 #include "aprs.h"
 #include "flash.h"
 #include "watchdog.h"
+#include "sleep.h"
 
 /*
  * Sequence determines in which order log packets are sent out
diff --git a/tracker/software/threads/threads.c b/tracker/software/threads/threads.c
index 9428044..8cc1db4 100644
--- a/tracker/software/threads/threads.c
+++ b/tracker/software/threads/threads.c
@@ -5,6 +5,7 @@
 #include "threads.h"
 #include "tracking.h"
 #include "watchdog.h"
+#include "image.h"
 #include "pi2c.h"
 #include "pac1720.h"
 
diff --git a/tracker/software/threads/threads.h b/tracker/software/threads/threads.h
index 75977b7..99d7663 100644
--- a/tracker/software/threads/threads.h
+++ b/tracker/software/threads/threads.h
@@ -1,13 +1,7 @@
 #ifndef __MODULES_H__
 #define __MODULES_H__
 
-#include "position.h"
-#include "image.h"
-#include "tracking.h"
-#include "log.h"
-#include "sgp4.h"
-#include "config.h"
-#include "types.h"
+#include "ch.h"
 
 void start_essential_threads(void);
 
diff --git a/tracker/software/threads/tracking.c b/tracker/software/threads/tracking.c
index f17c70f..766fb9f 100644
--- a/tracker/software/threads/tracking.c
+++ b/tracker/software/threads/tracking.c
@@ -1,6 +1,7 @@
 #include "ch.h"
 #include "hal.h"
 
+#include "tracking.h"
 #include "debug.h"
 #include "ptime.h"
 #include "config.h"
diff --git a/tracker/software/types.h b/tracker/software/types.h
index b47a551..8ad0109 100644
--- a/tracker/software/types.h
+++ b/tracker/software/types.h
@@ -1,6 +1,9 @@
 #ifndef __TYPES_H__
 #define __TYPES_H__
 
+//#define HIGH	true
+//#define LOW		false
+
 typedef enum { // Modulation type
 	MOD_NOT_SET,
 	MOD_OOK,