diff --git a/arch/cpu/cc2538/dev/cc2538-rf.c b/arch/cpu/cc2538/dev/cc2538-rf.c
index bddfcc942..e3a548067 100644
--- a/arch/cpu/cc2538/dev/cc2538-rf.c
+++ b/arch/cpu/cc2538/dev/cc2538-rf.c
@@ -140,6 +140,8 @@ static const output_config_t output_power[] = {
   {-24, 0x00 },
 };
 
+static radio_result_t get_value(radio_param_t param, radio_value_t *value);
+
 #define OUTPUT_CONFIG_COUNT (sizeof(output_power) / sizeof(output_config_t))
 
 /* Max and Min Output Power in dBm */
@@ -394,6 +396,48 @@ get_sfd_timestamp(void)
   return RTIMER_NOW() - RADIO_TO_RTIMER(timer_val - sfd);
 }
 /*---------------------------------------------------------------------------*/
+/* Enable or disable radio test mode emmiting modulated or unmodulated
+ * (carrier) signal. See User's Guide pages 719 and 741.
+ */
+static uint32_t prev_FRMCTRL0, prev_MDMTEST1;
+static uint8_t was_on;
+
+static void
+set_test_mode(uint8_t enable, uint8_t modulated)
+{
+  radio_value_t mode;
+  get_value(RADIO_PARAM_POWER_MODE, &mode);
+
+  if(enable) {
+    if(mode == RADIO_POWER_MODE_CARRIER_ON) {
+      return;
+    }
+    was_on = (mode == RADIO_POWER_MODE_ON);
+    off();
+    prev_FRMCTRL0 = REG(RFCORE_XREG_FRMCTRL0);
+    /* This constantly transmits random data */
+    REG(RFCORE_XREG_FRMCTRL0) = 0x00000042;
+    if(!modulated) {
+      prev_MDMTEST1 = REG(RFCORE_XREG_MDMTEST1);
+      /* ...adding this we send an unmodulated carrier instead */
+      REG(RFCORE_XREG_MDMTEST1) = 0x00000018;
+    }
+    CC2538_RF_CSP_ISTXON();
+  } else {
+    if(mode != RADIO_POWER_MODE_CARRIER_ON) {
+      return;
+    }
+    CC2538_RF_CSP_ISRFOFF();
+    REG(RFCORE_XREG_FRMCTRL0) = prev_FRMCTRL0;
+    if(!modulated) {
+      REG(RFCORE_XREG_MDMTEST1) = prev_MDMTEST1;
+    }
+    if(was_on) {
+      on();
+    }
+  }
+}
+/*---------------------------------------------------------------------------*/
 /* Netstack API radio driver functions */
 /*---------------------------------------------------------------------------*/
 static int
@@ -806,8 +850,12 @@ get_value(radio_param_t param, radio_value_t *value)
 
   switch(param) {
   case RADIO_PARAM_POWER_MODE:
-    *value = (REG(RFCORE_XREG_RXENABLE) && RFCORE_XREG_RXENABLE_RXENMASK) == 0
-      ? RADIO_POWER_MODE_OFF : RADIO_POWER_MODE_ON;
+    if((REG(RFCORE_XREG_RXENABLE) & RFCORE_XREG_RXENABLE_RXENMASK) == 0) {
+      *value = RADIO_POWER_MODE_OFF;
+    } else {
+      *value = (REG(RFCORE_XREG_FRMCTRL0) & RFCORE_XREG_FRMCTRL0_TX_MODE) == 0
+        ? RADIO_POWER_MODE_ON : RADIO_POWER_MODE_CARRIER_ON;
+    }
     return RADIO_RESULT_OK;
   case RADIO_PARAM_CHANNEL:
     *value = (radio_value_t)get_channel();
@@ -896,6 +944,11 @@ set_value(radio_param_t param, radio_value_t value)
       off();
       return RADIO_RESULT_OK;
     }
+    if(value == RADIO_POWER_MODE_CARRIER_ON ||
+       value == RADIO_POWER_MODE_CARRIER_OFF) {
+      set_test_mode((value == RADIO_POWER_MODE_CARRIER_ON), 0);
+      return RADIO_RESULT_OK;
+    }
     return RADIO_RESULT_INVALID_VALUE;
   case RADIO_PARAM_CHANNEL:
     if(value < CC2538_RF_CHANNEL_MIN ||
diff --git a/arch/dev/cc2420/cc2420.c b/arch/dev/cc2420/cc2420.c
index a1572b0ef..545f917ac 100644
--- a/arch/dev/cc2420/cc2420.c
+++ b/arch/dev/cc2420/cc2420.c
@@ -114,6 +114,7 @@ PROCESS(cc2420_process, "CC2420 driver");
 #define CORR_THR(n) (((n) & 0x1f) << 6)
 #define FIFOP_THR(n) ((n) & 0x7f)
 #define RXBPF_LOCUR (1 << 13);
+#define TX_MODE (3 << 2)
 
 int cc2420_on(void);
 int cc2420_off(void);
@@ -135,6 +136,8 @@ static void set_poll_mode(uint8_t enable);
 static void set_send_on_cca(uint8_t enable);
 static void set_auto_ack(uint8_t enable);
 
+static void set_test_mode(uint8_t enable, uint8_t modulated);
+
 signed char cc2420_last_rssi;
 uint8_t cc2420_last_correlation;
 
@@ -156,7 +159,11 @@ get_value(radio_param_t param, radio_value_t *value)
   }
   switch(param) {
   case RADIO_PARAM_POWER_MODE:
-    *value = receive_on ? RADIO_POWER_MODE_ON : RADIO_POWER_MODE_OFF;
+    if((getreg(CC2420_MDMCTRL1) & TX_MODE) & 0x08) {
+      *value = RADIO_POWER_MODE_CARRIER_ON;
+    } else {
+      *value = receive_on ? RADIO_POWER_MODE_ON : RADIO_POWER_MODE_OFF;
+    }
     return RADIO_RESULT_OK;
   case RADIO_PARAM_CHANNEL:
     *value = cc2420_get_channel();
@@ -237,6 +244,11 @@ set_value(radio_param_t param, radio_value_t value)
       cc2420_off();
       return RADIO_RESULT_OK;
     }
+    if(value == RADIO_POWER_MODE_CARRIER_ON ||
+       value == RADIO_POWER_MODE_CARRIER_OFF) {
+      set_test_mode((value == RADIO_POWER_MODE_CARRIER_ON), 0);
+      return RADIO_RESULT_OK;
+    }
     return RADIO_RESULT_INVALID_VALUE;
   case RADIO_PARAM_CHANNEL:
     if(value < 11 || value > 26) {
@@ -1120,3 +1132,45 @@ set_send_on_cca(uint8_t enable)
   send_on_cca = enable;
 }
 /*---------------------------------------------------------------------------*/
+/* Enable or disable radio test mode emmiting modulated or unmodulated
+ * (carrier) signal. See datasheet page 55.
+ */
+static uint16_t prev_MDMCTRL1, prev_DACTST;
+static uint8_t was_on;
+
+static void
+set_test_mode(uint8_t enable, uint8_t modulated)
+{
+  radio_value_t mode;
+  get_value(RADIO_PARAM_POWER_MODE, &mode);
+
+  if(enable) {
+    if(mode == RADIO_POWER_MODE_CARRIER_ON) {
+      return;
+    }
+    was_on = (mode == RADIO_POWER_MODE_ON);
+    off();
+    prev_MDMCTRL1 = getreg(CC2420_MDMCTRL1);
+    setreg(CC2420_MDMCTRL1, 0x050C);
+    if(!modulated) {
+      prev_DACTST = getreg(CC2420_DACTST);
+      setreg(CC2420_DACTST, 0x1800);
+    }
+    /* actually starts the test mode */
+    strobe(CC2420_STXON);
+  } else {
+    if(mode != RADIO_POWER_MODE_CARRIER_ON) {
+      return;
+    }
+    strobe(CC2420_SRFOFF);
+    if(!modulated) {
+      setreg(CC2420_DACTST, prev_DACTST);
+    }
+    setreg(CC2420_MDMCTRL1, prev_MDMCTRL1);
+    /* actually stops the carrier */
+    if(was_on) {
+      on();
+    }
+  }
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/dev/radio.h b/os/dev/radio.h
index e6ca64f3d..e279e9efe 100644
--- a/os/dev/radio.h
+++ b/os/dev/radio.h
@@ -196,7 +196,9 @@ enum {
 /* Radio power modes */
 enum {
   RADIO_POWER_MODE_OFF,
-  RADIO_POWER_MODE_ON
+  RADIO_POWER_MODE_ON,
+  RADIO_POWER_MODE_CARRIER_ON,
+  RADIO_POWER_MODE_CARRIER_OFF
 };
 
 /**