diff --git a/lorawan_toa.py b/lorawan_toa.py
index bfe4967..b9c4066 100644
--- a/lorawan_toa.py
+++ b/lorawan_toa.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-# 4.1.1.6. LoRaTM Packet Structure, SX1276/77/78/79 Datasheet
-# http://www.semtech.com/images/datasheet/sx1276_77_78_79.pdf
+# 4.1.1.6. LoRaTM Packet Structure, SX1276/77/78/79 Datasheet Rev.5 Aug 2016
+# http://www.semtech.com/images/datasheet/sx1276.pdf
 
 import math
 
@@ -18,45 +18,57 @@ def mpsrange(a, b):
 def get_toa(n_size, n_sf, n_bw=125, enable_dro=1, disable_h=0, n_cr=1,
             n_preamble=8):
     '''
-    return the time on air in milisecond.
-    n_size:
-        PL in the fomula.  PHY Payload size in byte (= MAC Payload + 5)
-    n_sf: SF (12 to 7)
-    n_bw: Bandwidth in kHz.  default is 125 kHz for AS923.
-    enable_dro:
-        DE in the fomula.
-        1 when the low data rate optimization is enabled.
-        0 for disabled.
-        LoRaWAN always use the low data optimization.
-    disable_eh:
-        H in the fomula.
-        0 when the explicit header is enabled.
-        1 when no header is present.
-        LoRaWAN always use the header.
-    n_cr:
-        CR in the fomula, should be from 1 to 4.
-        Coding Rate = (n_cr/(n_cr+1)).
-        LoRaWAN takes alway 1.
-    n_preamble:
-        The preamble length in bit.
-        default is 8 in AS923.
+    Parameters:
+        n_size:
+            PL in the fomula.  PHY Payload size in byte (= MAC Payload + 5)
+        n_sf: SF (12 to 7)
+        n_bw: Bandwidth in kHz.  default is 125 kHz for AS923.
+        enable_dro:
+            DE in the fomula.
+            1 when the low data rate optimization is enabled.
+            0 for disabled.
+            LoRaWAN always use the low data optimization.
+        disable_eh:
+            IH in the fomula.
+            0 when the explicit header is enabled.
+            1 when no header is present.
+            LoRaWAN always use the header.
+        n_cr:
+            CR in the fomula, should be from 1 to 4.
+            Coding Rate = (n_cr/(n_cr+1)).
+            LoRaWAN takes alway 1.
+        n_preamble:
+            The preamble length in bit.
+            default is 8 in AS923.
+    Return:
+        dict type contains below:
+        r_sym: symbol rate in *second*
+        t_sym: the time on air in millisecond*.
+        t_preamble:
+        v_ceil:
+        n_payload:
+        t_payload:
+        t_packet: the time on air in *milisecond*.
     '''
-    t_sym = math.pow(2, n_sf) / (n_bw*1000.) * 1000.
+    r_sym = (n_bw*1000.) / math.pow(2,n_sf)
+    t_sym = 1000. / r_sym
     t_preamble = (n_preamble + 4.25) * t_sym
     a = 8.*n_size - 4.*n_sf + 28 + 16 - 20.*disable_h
     b = 4.*(n_sf-2.*enable_dro)
     v_ceil = a/b
-    nb_sym_payload = 8 + max(math.ceil(a/b)*(n_cr+4), 0)
-    t_payload = nb_sym_payload * t_sym
-    t_frame = t_preamble+ t_payload
+    n_payload = 8 + max(math.ceil(a/b)*(n_cr+4), 0)
+    t_payload = n_payload * t_sym
+    t_packet = t_preamble+ t_payload
 
     ret = {}
+    ret["r_sym"] = r_sym
     ret["t_sym"] = t_sym
+    ret["n_preamble"] = n_preamble
     ret["t_preamble"] = t_preamble
     ret["v_ceil"] = v_ceil
-    ret["nb_sym_payload"] = nb_sym_payload
+    ret["n_payload"] = n_payload
     ret["t_payload"] = t_payload
-    ret["t_frame"] = round(t_frame, 3)
+    ret["t_packet"] = round(t_packet, 3)
 
     return ret
 
@@ -102,8 +114,6 @@ if __name__ == "__main__" :
     opt = parse_args()
     ret = get_toa(opt.n_size, opt.n_sf, n_bw=opt.n_bw, enable_dro=opt.v_de,
                   disable_h=opt.v_h, n_cr=opt.n_cr, n_preamble=opt.n_preamble)
-    ret0 = get_toa(0, opt.n_sf, n_bw=opt.n_bw, enable_dro=opt.v_de,
-                   disable_h=opt.v_h, n_cr=opt.n_cr, n_preamble=opt.n_preamble)
     if opt.f_verbose:
         print "PHY payload size    : %d Bytes" % opt.n_size
         print "MAC payload size    : %d Bytes" % (opt.n_size-5)
@@ -112,15 +122,23 @@ if __name__ == "__main__" :
         print "Low data rate opt.  : %s" % ("enable" if opt.v_de else "disable")
         print "Explicit header     : %s" % ("disable" if opt.v_h else "enable")
         print "CR (coding rate)    : %d (4/%d)" % (opt.n_cr, 4+opt.n_cr)
+        print "Symbol Rate         : %.3f symbol/s" % ret["r_sym"]
+        print "Symbol Time         : %.3f msec/symbol" % ret["t_sym"]
         print "Preamble size       : %d symbols" % opt.n_preamble
-        print "Other symbol size   : %d symbols" % ret["nb_sym_payload"]
-        print "Symbol Time         : %.3f msec" % ret["t_sym"]
+        print "Packet symbol size  : %d symbols" % ret["n_payload"]
         print "Preamble ToA        : %.3f msec" % ret["t_preamble"]
         print "Payload ToA         : %.3f msec" % ret["t_payload"]
-        print "Time on Air         : %.3f msec" % ret["t_frame"]
+        print "Time on Air         : %.3f msec" % ret["t_packet"]
         if opt.debug_level:
-            print "MAC frame data rate : %.3f bps" % ((8.*(opt.n_size-5)) /
-                                    ((ret["t_frame"]-ret0["t_frame"])/1000.))
+            ret0 = get_toa(0, opt.n_sf, n_bw=opt.n_bw,
+                           enable_dro=opt.v_de, disable_h=opt.v_h,
+                           n_cr=opt.n_cr, n_preamble=opt.n_preamble)
+            print "PHY PL=0 ToA        : %.3f msec" % (ret0["t_packet"])
+            # preamble=8 cr=1? payload-len=7? crc=16 (payload) payload-crc=16
+            # =? 48 ==> 6 bytes ?
+            t0 = (ret["t_packet"]-ret0["t_packet"])/1000.
+            print "PHY fr.dr.(48b) 7:15: %.3f bps" % ((8.*opt.n_size+48)/t0)
+            print "MAC frame DR        : %.3f bps" % ((8.*(opt.n_size)) /t0)
             print "Ceil(x)             : %.3f" % ret["v_ceil"]
     else:
-        print "%.3f" % ret["t_frame"]
+        print "%.3f" % ret["t_packet"]