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For this page:
INTERNAL LINKS
THE NERC MST RADAR FACILITY AT ABERYSTWYTH
FILE FORMAT FOR VERSION-0 MST RADAR IQ DATA
All raw MST radar data files are Version-0
However, users are encouraged to make use of Version-2 MST radar data products.
Click here to find out more about the different versions of the signal processing.

File contents
These files contain (pre-spectral) in-phase (I) and quadrature (Q) radar return samples.

File naming convention:
iqYYMMDD_hhmm.dd

YY is a 2-digit year [00 - 99]
MM is a 2-digit month [01 - 12]
DD is a 2-digit day [01 - 31]
hh is a 2-digit hour [00 - 23]
DD is a 2-digit minute [00 - 59]
dd is the integer number of minutes covered by the file
Click here for the background to the file naming convention.

File location: /badc/mst/data/mst-raw/iq
Click here for the location of other files.

Archiving convention: YYYY
Click here for a further explanation.

File availability
IQ data are not typically recorded and so files exist only when they the data have been stored as part of a special campaign.

File format
The data are stored in non-standard format binary files, as described below:

			IQ DATA FILES
			--------------

	File name :-  IQyymmdd_hhmm.min

	RANDOM ACCESS FILE  -  UNFORMATTED
	RECORD = 64 BYTES

	File layout.
	------------

 	    Dwell 1,Cycle 1		  Dwell 2,Cycle 1
	PB+IQD,IQD,IQD,.....IQD,PB+IQD,IQD,IQD,IQD,.....etc...

	    		  Dwell x,Cycle y
	....,IQD,IQD,PB+IQD,IQD,IQD,IQD,.....IQD,IQD,BREC


	PARAMETER BLOCK ( PB ) ( Start of Each Dwell )
	----------------------

	Uses 48 bytes out of 64 available.
	Following bytes are data values.
	NB !! PB allways at the start of a record.

	B = BYTE , I2 = INTEGER*2, I4 = INTEGER*4

	LTX	B	Length of Transmitter pulse ( uSec ).
	NCC	B	Pulse Code Resolution.
			0 = Uncoded , 1 = 8 uS , 2 = 4 uS
			3 = 2 uS , 4 = 1 uS
	IPI	I2	Pulse Repetion Interval ( uSec ).
	NPP	I2	Number of Coherent Pulse Additions.
	LFT	I2	Length of FFT.
	NAV	I2	Number of FFTs Averaged together.
	NH1	I2	Start of First Height Range ( Bin No. ).
	NH2	I2	End of First Height Range ( Bin No. ).
	NBM	I2	Beam Number.
	IY	I2	YEAR in Form 90,91,92 etc.
	IMN	I2	MONTH ( 0 - 12 )
	ID	I2	DAY ( 0 - 31 )
	IH	I2	HOUR ( 0 - 23 )	     ]
	IM	I2	MINUTE ( 0 - 59 )    ] - Dwell Start time     
	IS	I2	SECONDS ( 0 - 59 )   ]     
	NH3	I2	Start of Second Height Range ( Bin No. ).
	NH4	I2	End of Second Height Range ( Bin No. ).
	NHI	I2	Height Interval in Bins.
	NRX	B	Receiver Bandwidth ( uSec ).
	DMP	B	Raw Data Collection Flag.
			Negative value if Raw Data File Collected.
	NDW	I2	Dwell Number.
	NCY	I2	Cycle Number.
	MST	I2	Run Number.
	NRS	I2	Number right shifts in input data.
        NXR     I4      Record number of next PB.


	IQ DATA ( IQD )
	-----------------------
	
	 Inphase (I) and Quadrature (Q) data required for
	Doppler spectra calculation.
         This data is stored as sets of 16 compressed integer
        values. Compression is achieved by only using the 
	number of bits required to store the range of integers
	in the 16 value set.
	 The first 4 bits of the set give the number of bits 
        minus one used to store each data value.
         The values are unsigned so that an offset has to
	subtracted from the number to get the true value.
	
	If n is the 4 bit value then the value of the number
	is :-  value - (2^n).  
        Using n+1 bits to extract the value.
        
	 The data is stored as all the I samples for the first 
	height bin followed by all the Q samples, then the second 
	height bin and so on. Upper height IQ data immediately 
	follows lower height IQ data.
	

	BLANK RECORD ( BREC )
	------------------------
		
	EOF 32 * I2	Zeros 


	DATA IN FILE
	------------

	 When data is aquired on the MST Radar system a setup file
	is used to store the data collection parameters.

	 The radar system uses the information in this setup file to set 
	the radar parameters for each beam before it starts to collect 
	data on that beam.

	 This information is copied to the parameter block for that beam.
	Data is collected on a given beam direction for long enough
	to collect all the data points required for the FFT length and
	FFT bandwidth specified in the setup file.
	FFT bandwidth is :-  1E6 / (IPI * NPP)  ( Hz ).

	 Up to 20 beams may be used when collecting data and the data
	for each beam is called a Dwell.

	 Data collected for a set of beams is called a Cycle and usually
	there will be more than one Cycle in an Observation.
	Therefore each beam collected is labelled with its Dwell and
	Cycle number.

	 The first height range refers to data collected below 30 Km
	and the second height range is for data collected above 58 Km.
	Height of data collected is referenced by range bin which are
	at intervals of 150 metres.

	To obtain the true height of a given bin an offset must be 
	subtracted to correct for various time delays in the radar.

	 IQ Data is obtained from the preprocessor data.
	The preprocessor data consists of two sets of inphase and 
	quadrature data, collected from the two phase detector outputs 
	of the radar receiver, which have been summed over 81.92 mS.

	 If coding was used the first set contains the coded data
	and the second set the complementary coded data.

	 The aquisition programme decodes this data if coding was used 
	and sums it if not. 

	 The data may be right shifted to prevent overflow depending on 
	the pulse repetion interval and length of code used.
	Additional summing of the data takes place if the FFT 
	bandwidth required is less than 12 Hz, this also may require 
	the data to right shifted.

	 This data, which can now be used to compute the Doppler spectra
	for the bins collected, is saved in this file as 'raw' data.
	Doppler spectra are 64,128,256 or 512 points in length
	and may also be incoherently averaged.

	The data is stored as I then Q with height for the first time
        sample followed by I & Q with height for the second time sample
        and so on until the last time sample.

        Upper height IQ data immediately follows lower height IQ data.
        The total amount of IQ data saved for each Dwell is :-
        16 * (1 + INT((Lower Bins + Upper Bins - 1) / 16))  Bins.
        ( i.e. sets of 16 height bins ).


Internal Links:
Return to the top of the page
Gaining access to the data
File naming convention
Data archiving convention
Data locations
The differences between signal processing versions
The contents of other data files
Page maintained by David Hooper
Last updated 13th January 2005