LDI DIGISONDE 4D - Page 274

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DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
SECTION 5 - SYSTEM SOFTWARE – ANNEX C 5-77
Table 5C- 44: Length of the SBF Frequency Groups Depending on Ionogram Settings
NUMBER OF HEIGHTS
(PREFACE Char #36-37)
NUMBER OF FREQUENCY
GROUPS IN A BLOCK
NUMBER OF RANGE
BINS STORED IN A
GROUP
LENGTH OF A
FREQUENCY GROUP
(BYTES)
128
30
128
134
256
15
256
262
512
8
498
504
5:162. For each sounding frequency, one or two Frequency Groups are stored depending on a setting of O/X
polarization option, A, PREFACE Char #29. If A is less than 8, both polarizations are stored each taking an
individual Frequency Group, otherwise only an O polarization height profile is stored for each frequency. Each
range bin takes 1 byte in a SBF Frequency Group (see Table 5C- 45 and Table 5C- 46).
Table 5C- 45: Content of an Individual Range Bin in SBF File Format
MSB
LSB
5-bit Amplitude
3-bit Doppler Number
Byte 1
Table 5C- 46: Individual Bit Sections of the Range Bin
Item
Units
Range
Accuracy
Precision
Type
Format
Amplitude
3 dB
0-31
1
1
5 bit unsigned
integer
-
Doppler
Number
See text
0-7
1
1
3 bit unsigned
integer
-
5:163. The 6-byte PRELUDE precedes each set of range bins in a Frequency Group (see Table 5C- 47). The
PRELUDE uses a packed-BCD encoding scheme, and the stored frequency reading is the actual sounding fre-
quency. The offset from the nominal frequency is stored in byte #4. If the offset was caused by forcing of
sounding out of restricted frequency range, the actual frequency reading is given and the offset is set to E (hex)
to indicate the case.