Australian IPS Spectrograph Data Format

1. Data Format

IPS holds Spectrograph data files and images from two stations: Culgoora and Learmonth. The data files are binary daily file. They are avaialble on IPS website and FTP server.

Header

Channel header

Channel data

Header

Channel header

Channel data

Header

Channel header

Channel data

……………

Details in header, channel header and channel data are listed as following table.

Item	Sub-item	Bytes	Example	Note
Header (8 bytes)	Year	1	93	year value,+1900 or 2000. The last 2 bytes normally is useless for data interpreting
	Month	1	15
	Day	1	6
	Hour	1	13
	Minute	1	2
	Second	1	16
	Data_OK	1
	unused	1
Channel header (32 bytes)	Start Frequency (MHz)	2	57	Culdgoora: Each band uses 8 bytes,4 bands use 32 bytes. Each band has 501 data values. If data value <0, +256. Learmonth: 2 bands use 16 bytes. Each band has 401 bytes values.
	End Frequency (MHz)	2	180
	Resbw (Hz or kHz)	2	100
	Ref-level (dBm)	1	-50
	Range (dBm)	1	40
	:	:	:
Channel data (2004 bytes)	Data value (dBm)	1	234 193 197 232	Culgoora uses 4x501 bytes, Learmonth uses 2x401 bytes.
:	:	:
Header (8 bytes)	:	:
Channel header (32 bytes)	:	:		Culgoora uses 32 bytes. Learmonth uses 16 bytes
Channel data (2004 bytes)	:	:		Culgoora uses 2004 bytes. Learmonth uses 802 bytes.
:	:	:

• Resbw (Resolution band), Ref_level(reference level) and Range. These three parameters are used to setup the analyser. Neither of them is essential for data interpreting.
• Normally every two seconds a scan.
• Culgoora has 4 bands: 18-57, 57-180, 180-570 and 570-1800 MHz. So a scan is 2044 (8 + 4x8 + 4x501) bytes in total.
• Learmonth has 2 bands: 25-75 and 75-180 MHz. So a scan is 826 (8 + 2x8 + 2x401) bytes in total.

A part of programming code of data structure is also available for Culgoora and Learmonth Spectrograph data separately.

2. A text description of Culgoora spectrograph data file format.

There is one data record every 3 seconds. A record consists of 2044 bytes arranged as follows:

record header 8 bytes
A-band header 8 bytes
B-band header 8 bytes
C-band header 8 bytes
D-band header 8 bytes
A-band data 501 bytes
B-band data 501 bytes
C-band data 501 bytes
D-band data 501 bytes

where the record header consists of:

year 1 byte char
month 1 byte char
day 1 byte char
hour 1 byte char
minute 1 byte char
second 1 byte char
data OK 1 byte char*
unused (=0) 1 byte char

and the band headers are structured like this:

start freq 2 byte int
end freq 2 byte int
resolution 2 byte int*
ref level 1 byte char*
range 1 byte char*

I am yet to find documentation on the terms marked with a "*".

The data run upwards in frequency and the sampling is linear.

A-band is 18-57 MHz
B-band is 57-180 MHz
C-band is 180-570 MHz
D-band is 570-1800 MHz

For example:

the first datum in A-band should be at 18.0 MHz,
the second should be at 18+((57-18)/501) MHz,
the third should be at 18+2x((57-18)/501) MHz, etc.