Document title: Description of ISIS 2 FULL and AVERAGE ionogram file format
Project: ISIS
NDADS Datatypes: 
  ISIS2_TOPS_FULL_24S_OS2BIN
  ISIS2_TOPS_AVG_24S_OS2BIN
  ISIS2_TOPS_AVG_24S_CDF
  ISIS2_TOPS
  ISIS2_CDF
Super-EID: DOCUMENTS
There may be other documents also identified by this super-EID.
NDADS filename: ISIS2_IONOGRAM_FORMAT.DOC
TRF entry: b46764.txt in NSSDC's controlled digital document library, Mar. 1998.
Document text follows:
----------------------

Description of ISIS 2 FULL and AVERAGE ionogram file format
-----------------------------------------------------------

Items starting with "Satellite ID number" and ending with "Scan Line Number of
Start of Swept Portion" are all contained in the first record. Each entry 
after that is a separate record. 

Each record is preceded and followed by a 4 byte descriptor that contains the
length of the record. For example the first record is 160 bytes in length. 
Therefore to get the entire record you would have to allow for 168 bytes 
(4+160+4). 

The "Types" of data are I*1 (1 byte integer), I*4 (4 byte integer), R*4 (4 byte
real) and R*8 (8 byte real). 

Any value for the below variables found to be outside the valid value for that
variable indicates the variable was undetermined. 

Description of Variable                     Type    Comments
-------------------------------------------------------------------
Satellite ID number (One Digit ID)           I*4 (1:AL1,2:AL2,3:IS1,4:IS2)
Station Code number (Two Digit Code)         I*4
Transmitter Power Code                       I*4 (1:400W(PRI),2:400W(SEC))
Sounder/Receiver Code                        I*4 (0:OFF,1:ON)
Swept Freq. Range Code                       I*4 (0:NORMAL,1:EXTENDED)
DMODE Code                                   I*4 (0:OFF,1:ON)
GMODE Code                                   I*4 (0:OFF,1:ON)
Sounder Mixed Mode                           I*4 (0:OFF,1:ON)
AIT Mode                                     I*4 (0:OFF,1:ON)
Fixed Freq. Code (Freq of Fixed Freq (MHz))  I*4 (0:OFF,1:0.25,2:0.48,3:1.00,
                                                  4:1.95,5:4.00,6:9.303)
Year (Last 2 Digits)                         I*4 Frame Sync UT
Day of Year                                  I*4 Frame Sync UT
Hour                                         I*4 Frame Sync UT
Minute                                       I*4 Frame Sync UT
Second (to the microsecond)                  R*8 Frame Sync UT
LMT (HH)                                     I*4 At time of Frame Sync
LMT (MM)                                     I*4 At time of Frame Sync
GGLatitude (Deg)                             R*4 At time of Frame Sync
GGLongitude (Deg)                            R*4 At time of Frame Sync
Height (km)                                  R*4 At time of Frame Sync
GMLTM (HH)                                   I*4 At time of Frame Sync
GMLTM (MM)                                   I*4 At time of Frame Sync
GMLAT (Deg)                                  R*4 At time of Frame Sync
GMLONG (Deg)                                 R*4 At time of Frame Sync
Gyro Frequency (MHz)                         R*4 At time of Frame Sync
Invariant Latitude (Deg)                     R*4 At time of Frame Sync
Dip (Deg)                                    I*4 At time of Frame Sync
CHI (Deg)                                    I*4 At time of Frame Sync
Sunlight                                     I*4 (1:SL,2:NSL) 
L Shell                                      R*4 At time of Frame Sync 
C.E.P.                                       I*4 (0:OFF,1:ON) 
VLF Rcvr.                                    I*4 (0:OFF,1:ON) 
R.P.A.                                       I*4 (0:OFF,1:ON) 
I.M.S.                                       I*4 (0:OFF,1:ON) 
S.P.S.                                       I*4 (0:OFF,1:ON) 
E.P.D.                                       I*4 (0:OFF,1:ON) 
Red. Line Phot.                              I*4 (0:OFF,1:ON) 
Aur. Scan. Phot.                             I*4 (0:OFF,1:ON) 
Scan Line Number of Start of Swept Portion   I*4
1st Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync) 
2nd Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
3rd Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
4th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
5th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
6th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
7th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
8th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
9th Freq. Marker: Frequency (MHz) Time (ms)  R*8,R*8 (ms after Frame Sync)
10th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
11th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
12th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
13th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
14th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
15th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
16th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
17th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
18th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
19th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
20th Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
21st Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)
22nd Freq. Marker: Frequency (MHz) Time (ms) R*8,R*8 (ms after Frame Sync)

Number of Columns[#C]    Number of Rows[#R]  I*4,I*4   Dimensions of
                                                       Arrays and Matrix
                                                       that follow (for non-
                                                       average ionogram the
Delay Time(R1); where R1=1,#R (in ms)        R*8       number of rows fixed
Apparant Range(R1); where R1=1,#R (in km)    R*8       at 892; average fixed
                                                       at 223)

The next record is repeated #C times (ie; C1=1,#C)

Time(C1)    Freq(C1)   Amplitude(R1,C1)      R*8,R*8,I*1
(in ms)     (in MHz)   (where R1=1,#R)