explain more of 50BPS data so we can parse it for ephemeris

decode/raw4t/85_0X.txt

@@ -0,0 +1,81 @@
+---- trying to decode LEADIN 0x8501 ----
+16:21:38.101 currently unsupported LEAD-IN 8501: 00/00/0006 16:21:38.101 (0) 85 01 01 1D 00 03 FF 03 00 00 00 
+#01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 -- same
+#00 00 00 0A 89 DD 83 81 46 78 F1 C6 A7 7D 3A 02 8A C0 06 10 -- same 	# seq1=0097 seq2=0008 len=0033
+
+16:21:38.147 GPSD knows MID 0x08 --  subframe data MID 8 (extract leap-second from this): 50 BPS data -- hex 
+00 1D 
+# 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 -- same 
+# 00 00 00 0A 89 DD 83 81 46 78 F1 C6 A7 7D 3A 02 8A C0 06 10 -- same
+
+----
+
+
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 01010101 01010101 01010101 01010101 01010101 0000000A 89DD8381 4678F1C6 A77D3A02 8AC00610 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 01010101 01010101 01010101 01010101 01010101 01010101 01010101 00000006 A77D3A02 8AC001EF 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 22C3062B EDBA7238 102AAAAC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 01010101 01010101 01010101 01010101 0000000B DA5495FC 2292AEC8 2AD294E3 CAAC6AB3 DBB1AB43 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 0002F92C 12598DC6 AFC524AF EAAAAA43 D5555543 C55AAABE B2AAB543 D5155544 2AAAA943 D551AA4D 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 00000014 11C583CB C09E5A68 0A16E45C 1C731985 6B6D117D 4B353642 B6B62A64 08BAAABC 2FAAA943 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: DD3CF9D4 12458C38 102AAAAC 2AAAAABC 2AAAAABC 2AAAAABC 2A56AABC 2AAAAABC 2AAAAABD 6AAAAABC 
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 22C3062B EDBA56C4 3064002C 07170495 59DE328A A183CE4C 169D7AEA 89CE1034 0000063A 91C2B474 
+
+----
+
+    from SVID 1D (unk 0503FF03FF0000)
+	50Bps raw 10 30-bit (FIXME expanded to 32-bit?) words: 
+	22C3062B EDBA7238 102AAAAC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 2AAAAABC 
+
+          00100010 11000011 00000110 00101011
+          11101101 10111010 01110010 00111000
+          00010000 00101010 10101010 10101100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+          00101010 10101010 10101010 10111100
+
+	*** WORD1:
+	TLM: 22 C3 06 2B ( 00100010 11000011 00000110 00101011 )
+	TLM,C,P:	     100010 11000011 0000011  00101011
+
+	parsing:
+	00			- 30 to 32 bit MSB padding, ignore
+	100010 11 		- preamble (b1-8)
+	000011 0000011		- TLM Message (b9-22 - military, unknown) 
+	0			- integrity status flag (b23)
+	0			- reserved bit (b24)
+	101011			- parity (b25-b30)	= 0x2B
+
+	*** WORD2:
+	HOW: ED BA 72 38 ( 11101101 10111010 01110010 00111000 )
+	HOW,t,P:             101101 10111010 0111001 000111000
+
+	parsing:
+	11			- 30 to 32 bit MSB padding, ignore
+	101101 10111010 011	- TOW-Count Message (b1-b17, Truncated)		= 0x16DD3 (OK!)
+	1			- Alert flag (b18)
+	0			- Anti-spoof flag (b19)
+	010			- subframe ID (b20-b22)				= subframe 2 (Ephemeris)
+	00			- Solved for bits to preserve parity check with zeros in bits 29 and 30 (b23-b24)
+	111000			- parity (b25-b30: b29 & b30 are always '00')	= 0x38
+
+50bps PAYLOAD #8: 08001d22c3062bedba7238102aaaac2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc
+50bps SiRF #8: a0a2 002b 08 00 1d 22c3062bedba7238102aaaac2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc 14b2 b0b3
+Channel: 08
+SV_ID: 00
+Subframe: 22c3062bedba7238102aaaac2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc2aaaaabc
+Subframe Length: 318
+Checksum: 0x14b2
+Checksum2: 0x14b2
+Checksum Match!
+Subframe ID: 0x2
+Satellite Ephemeris Data
+TLM: 0x22c306
+HOW: 0x2dba72
+TOW: 0x16dd3
+TLM,C,P: 100010110000110000011000101011
+HOW,t,P: 101101101110100111001000111000
+word3: 010000001010101010101010101100