Update to latest 2.1.1 rev of the capture frame format.

doc/capturefrm.txt

@@ -1,5 +1,5 @@
 AVS Capture Frame Format
-Version 2.1
+Version 2.1.1
 
 1. Introduction
 The original header format for "monitor mode" or capturing frames was
@@ -39,7 +39,7 @@ The following fields make up the AVS capture header:
 	8	mactime		uint64
 	16	hosttime	uint64
 	24	phytype		uint32
-	28	channel		uint32
+	28	frequency	uint32
 	32	datarate	uint32
 	36	antenna		uint32
 	40	priority	uint32
@@ -50,7 +50,7 @@ The following fields make up the AVS capture header:
 	60	encoding	uint32
 	64	sequence	uint32
 	68      drops           uint32
-        72      sniffer_addr    uint8[6]
+        72      receiver_addr   uint8[6]
         78      padding         uint8[2]
 	------------------------------
 	80
@@ -72,11 +72,17 @@ in bytes.
 Many WLAN devices supply a relatively high resolution frame reception
 time value.  This field contains the value supplied by the device.  If
 the device does not supply a receive time value, this field shall be
-set to zero.  The units for this field are microseconds.
+set to zero.  The units for this field are microseconds.  
+
+If possible, this time value should be absolute, representing the number
+of microseconds elapsed since the UNIX epoch.
 
 4.4 hosttime
 The hosttime field is set to the current value of the host maintained
-clock variable when the frame is received.
+clock variable when the frame is received by the host. 
+
+If possible, this time value should be absolute, representing the number 
+of microseconds elapsed since the UNIX epoch.
 
 4.5 phytype
 The phytype field identifies what type of PHY is employed by the WLAN 
@@ -94,11 +100,13 @@ device used to capture this frame.  The valid values are:
 	phytype_ofdm_dot11_a		 8
 	phytype_dss_ofdm_dot11_g	 9
 
-4.6 channel
-For all PHY types except FH, this field is just an unsigned integer
-and will be set to the current receiver channel number at the time 
-the frame was received.  For frequency hopping radios, this field
-is broken in to the following subfields:
+4.6 frequency
+
+This represents the frequency or channel number of the receiver at the 
+time the frame was received.  It is interpreted as follows:
+
+For frequency hopping radios, this field is broken in to the 
+following subfields:
 
 	Byte	Subfield
 	------------------------
@@ -107,6 +115,15 @@ is broken in to the following subfields:
 	Byte2	Hop Index
 	Byte3	reserved
 
+For non-hopping radios, the frequency is interpreted as follows:
+
+       Value                Meaning
+    -----------------------------------------
+       < 256	       Channel number (using externally-defined
+                         channelization)
+       < 10000         Center frequency, in MHz
+      >= 10000         Center frequency, in KHz
+
 4.7 datarate
 The data rate field contains the rate at which the frame was received
 in units of 100kbps.
@@ -190,11 +207,10 @@ This is a counter of the number of known frame drops that occured.  This
 is particularly useful when the system or hardware cannot keep up with 
 the sniffer load.
 
-4.16 sniffer_addr
-This specifies the mac address of the sniffer, six octets in length.
-This field is followed by two octets of padding to keep the structure 32-bit
-word aligned.
-
+4.16 receiver_addr
+This specifies the MAC address of the receiver of this frame.  
+It is six octets in length.  This field is followed by two octets of 
+padding to keep the structure 32-bit word aligned.
 
 ================================
 
@@ -207,3 +223,11 @@ Changes: v2->v2.1
  * Mactime is specified in microseconds, not nanoseconds
  * Added 64QAM, 16QAM, BPSK, QPSK encodings
 
+================================
+
+Changes: v2.1->v2.1.1
+
+ * Renamed 'channel' to 'frequency'
+ * Clarified the interpretation of the frequency/channel field.
+ * Renamed 'sniffer address' to 'receiver address'
+ * Clarified timestamp fields.