diff --git a/include/osmocore/gsmtap.h b/include/osmocore/gsmtap.h
index 81b9cc0..d6d40ba 100644
--- a/include/osmocore/gsmtap.h
+++ b/include/osmocore/gsmtap.h
@@ -1,11 +1,20 @@
 #ifndef _GSMTAP_H
 #define _GSMTAP_H
 
-/* gsmtap header, pseudo-header in front of the actua GSM payload*/
+/* gsmtap header, pseudo-header in front of the actua GSM payload */
+
+/* GSMTAP is a generic header format for GSM protocol captures,
+ * it uses the IANA-assigned UDP port number 4729 and carries
+ * payload in various formats of GSM interfaces such as Um MAC
+ * blocks or Um bursts.
+ *
+ * Example programs generating GSMTAP data are airprobe
+ * (http://airprobe.org/) or OsmocomBB (http://bb.osmocom.org/)
+ */
 
 #include <stdint.h>
 
-#define GSMTAP_VERSION		0x01
+#define GSMTAP_VERSION		0x02
 
 #define GSMTAP_TYPE_UM		0x01
 #define GSMTAP_TYPE_ABIS	0x02
@@ -22,41 +31,38 @@
 #define GSMTAP_BURST_ACCESS		0x08
 #define GSMTAP_BURST_NONE		0x09
 
-#define GSMTAP_UDP_PORT                 4729
+#define GSMTAP_CHANNEL_UNKNOWN	0x00
+#define GSMTAP_CHANNEL_BCCH	0x01
+#define GSMTAP_CHANNEL_CCCH	0x02
+#define GSMTAP_CHANNEL_RACH	0x03
+#define GSMTAP_CHANNEL_AGCH	0x04
+#define GSMTAP_CHANNEL_PCH	0x05
+#define GSMTAP_CHANNEL_SDCCH	0x06
+#define GSMTAP_CHANNEL_SDCCH4	0x07
+#define GSMTAP_CHANNEL_SDCCH8	0x08
+#define GSMTAP_CHANNEL_TCH_F	0x09
+#define GSMTAP_CHANNEL_TCH_H	0x0a
+#define GSMTAP_CHANNEL_ACCH	0x80
+
+#define GSMTAP_UDP_PORT			4729
 
 struct gsmtap_hdr {
-	uint8_t version;		/* version, set to 0x01 currently */
-	uint8_t hdr_len;		/* length in number of 32bit words */
-	uint8_t type;			/* see GSMTAP_TYPE_* */
-	uint8_t timeslot;		/* timeslot (0..7 on Um) */
+	uint8_t version;	/* version, set to 0x01 currently */
+	uint8_t hdr_len;	/* length in number of 32bit words */
+	uint8_t type;		/* see GSMTAP_TYPE_* */
+	uint8_t timeslot;	/* timeslot (0..7 on Um) */
 
-	uint16_t arfcn;			/* ARFCN (frequency) */
-	uint8_t noise_db;		/* noise figure in dB */
-	uint8_t signal_db;		/* signal level in dB */
+	uint16_t arfcn;		/* ARFCN (frequency) */
+	int8_t signal_dbm;	/* signal level in dBm */
+	int8_t snr_db;		/* signal/noise ratio in dB */
 
-	uint32_t frame_number;		/* GSM Frame Number (FN) */
+	uint32_t frame_number;	/* GSM Frame Number (FN) */
 
-	uint8_t burst_type;		/* Type of burst, see above */
-	uint8_t antenna_nr;		/* Antenna Number */
-	uint16_t res;			/* reserved for future use (RFU) */
+	uint8_t sub_type;	/* Type of burst/channel, see above */
+	uint8_t antenna_nr;	/* Antenna Number */
+	uint8_t sub_slot;	/* sub-slot within timeslot */
+	uint8_t res;		/* reserved for future use (RFU) */
 
 } __attribute__((packed));
 
-
-/* PCAP related definitions */
-#define TCPDUMP_MAGIC   0xa1b2c3d4
-#ifndef LINKTYPE_GSMTAP
-#define LINKTYPE_GSMTAP	2342
-#endif
-struct pcap_timeval {
-	int32_t tv_sec;
-	int32_t tv_usec;
-};
-
-struct pcap_sf_pkthdr {
-	struct pcap_timeval ts;		/* time stamp */
-	uint32_t caplen;		/* lenght of portion present */
-	uint32_t len;			/* length of this packet */
-};
-
 #endif /* _GSMTAP_H */