For Windows 3.1 users the following format will be used:

For a single channel auto spectra measurement, the file name is 'aaabc.ext', where 'aaa' is a three­digit point number (001, 002, 003 ... 999), 'b' is the measurement direction, i.e., X, Y, Z, R, T, P, U (rotation around X­axis), V (rotation around Y­axis) and W (rotation around Z­axis), end 'c' is the channel the measurement was taken from, i.e., A or B. For other single channel measurements, the 'c' is omitted from the file name.

For dual channel measurement, the file name is 'aaabcccd.ext', where 'aaa' is a three­digit point number (001, 002, 003,..., 999) of channel l and 'ccc' is the three­digit point number of channel 2. The values of 'b' and 'd' are the measurement directions, i.e., X, Y. Z. R. T. P. U (rotation around X­axis), V (rotation around Y­axis) and W (rotation around Z­axis) of channels 1 and 2 respectively.

For Windows 95 and Windows NT users the following format will be used:

For a single channel auto spectra measurement, the file name is 'aaabc.ext', where 'aaa' is a three­digit point number (0001, 0002, 0003 ... 3000), 'b' is the measurement direction, i.e., X, Y, Z, R, T, P, U (rotation around X­axis), V (rotation around Y­axis) and W (rotation around Z­axis), end 'c' is the channel the measurement was taken from, i.e., A or B. For other single channel measurements, the 'c' is omitted from the file name.

For dual channel measurement, the file name is 'aaabcccd.ext', where 'aaa' is a three­digit point number (0001, 0002, 0003,..., 3000) of channel l and 'ccc' is the three­digit point number of channel 2. The values of 'b' and 'd' are the measurement directions, i.e., X, Y. Z. R. T. P. U (rotation around X­axis), V (rotation around Y­axis) and W (rotation around Z­axis) of channels 1 and 2 respectively.

For calibration measurements, the file name is 'MICPAIR.CAL where a is 1, 2, or 3, indicating which microphone pair is stored in the file.

Note: The data in a calibration measurement must be normalized as discussed in the Measurement section ahead.

The file name extension 'ext' are as follows (Listings marked * are planned but not supported in the STARAcoustics v2.0.):

Auto Spectrum Calibration Coherence Cross Spectrum Frequency Response Auto Correlation Auto Spectrum Density Cross Correlation Cross Spectrum Density Curve fit FRF Impulse Response Linear Spectrum Intensity Time Domain Sound Pressure Composite Sound Power F1 Indicator F2 Indicator F3 Indicator F4 Indicator

APS CAL COH CPS FRF ACR* ASD* CCR* CSD* CFT* IRF* FRQ* INT TIM SPL CSP F1 F2 F3 F4

For example, the following files would be created to save the two auto spectra, the cross spectrum, the frequency response and the coherence function for a dual­channel measurement with response at point 3Z and excitation at 55X:

003ZB.APS 055XA.APS 055X003Z.CPS 055X003Z.FRF 055X003Z.COH

Auto spectrum of 3Z from Channel B Auto spectrum of 55X from Channel A Cross spectrum between 55X and 3Z Frequency Response between 55X and 3Z Coherence Function between 55X and 3Z

The memory requirements for the following standard data types are:

char	8 bits	1 byte
int	16 bits	2 bytes
float	32 bits	4 bytes

The Offset is the number of bytes from the beginning of the record.


MEASUREMENT TABLE
The user interfacing to the STAR System measurement data base must be aware of the internal format of the measurement data (what information is available) and the archiving of measurements to the disk in an orderly manner.


MEASUREMENT
TABLE
FORMAT

The measurement data record is saved to a disk file in binary format.

General Purpose Header ( 16 Bytes)

Measurement Header (636 Bytes)

Measurement Data (n * 2 * 4 Bytes)

Where "n" is the number of complex measurement data lines; n<=32000. Only the required amount of the measurement data is saved to disk. The data is stored in the order: frequency line l.real, frequency line l.imag, frequency line 2.real, frequency line 2.imag, etc.


MEASUREMENT TABLE
GENERAL PURPOSE
HEADER

The General Purpose Header consists of the following fields (Bold type variables are required functions; normal type variables are set but not used currently; italicized variables are not even set currently.):

Variable	Offset	Type	Description
revcode	0	int	Star Data Base Revision Code (=2832)
headerlen	2	int	Length of Header (=16)
entries	4	int	Not Used (=0)
pline	6	int	Not Used (=0)
sentries	8	int	Not Used (=0)
spline	10	int	Not Used (=0)
tentries	12	int	Not Used (=0)
tpline	14	int	Not Used (=0

The total memory required for the General Purpose Header is 16 bytes.

The 636­byte Measurement Header consists of the following fields:

datablockid	Measurement Data Block Identifier	420 bytes
xaxisrange	X-Axis Range Information	20 bytes
Channel 1	Channel 1 Measurement Information	98 bytes
Channel 2	Channel 2 Measurement Information	98 bytes

Offset from the beginning of the file: 16 bytes.


The 420­byte Measurement 'datablockid' structure contains the following information:

Variable	Offset	Type	Description
datatype misctype noelements msmcalval caltrace measid userlabel xlabel ylabel msmdate msmtime analzerid noave windowtype miscwindow wdwvalue spacing surface minreal maxreal minimag maximag maxmag mmdefined micpair ispeak encamp	0 2 4 6 10 26 154 274 290 306 322 338 362 364 366 382 386 390 392 396 400 404 408 412 414 415 416	datatype miscdatatype int float char[l6] char[128] char[120] char[16] char[16] char[16] char[16] char[24] int windowtype char[16] float float surfacetype float float float float float int char peatype float	Primary measurement type (=0 for FRF) Secondary measurement type (=0) Number of elements in datablock Overall calibration value (Must be set to 1.00) File name of calibration trace (null terminated) Measurement ID (null terminated) Optional user plot labels (null terminated) Optional x­axis label (null terminated) Optional y­axis label (null terminated) Measurement date (null terminated) Measurement time (null terminated) Analyzer ID (null terminated) Number of averages for data (=1) Window type Miscellaneous window description (null terminated) Noise BW/exponential time Microphone spacing (=0.0) Intensity surface (=0) Minimum real part of all lines Maximum real part of all lines Minimum imaginary part of all lines Maximum imaginary part of all lines Maximum magnitude of all lines 0=min/maxes undefined 1 =all min/maxes defined Microphone pair number 1, 2, or 3 (. CAL measurements only) RMS/Peak compensation, Auto Spectra A/B Excitation amplitude (=0.0)

NOTE: If maxreal­minreal<le­18 then maxreal=maxreal+abs(maxreal)+2e­18 and minreal=minreal-abs(minreal)­2e­ 18; similarly for the imaginary part. Maxmag=max (mag (line [i])) where 1 <= i <= number of lines. If maxmag<le­18 then maxmag=+2e­18. It is highly recommended that these min/maxes be computed to improve data base performance.

Offset from the beginning of the file: 436 bytes.

The 20­byte Measurement Header 'xaxisrange' xaxisrangetype structure contains the following information:

Variable	Offset	Type	Description
xlow	0	float	Start frequency/time of data
deltax	4	float	Delta frequency/time of data
xhigh	8	float	High frequency/time delay
xoffset	12	float	Center frequency/time delay
zoom	16	zoomtype	Zoom flag/code
code	18	codetype	Frequency/time code

Offset from the beginning of the file: 456 bytes for channel l and 554 bytes for channel 2.

The two 98­byte Measurement Headers 'Channel1' and 'Channel2' msminfotype structure are identical and each contain the following information:

Variable	Offset	Type	Description
point	0	ptdirtype	Point and direction
units	2	unitstype	Transducer units
unitslbl	4	char[8]	Transducer units label
xdcrid	12	char[24]	transducer id field
calfactor	36	float	Transducer calibration factor = 1
chnid	40	char[24]	Amplifier id field
gain	64	float	Amplifier gain/code
calcf	68	float	Cal factor(.CAL measurements only) corrected = calcf * measured
calfreq	72	float	Cal frequency (.CAL measurements only)
calcfdb	76	float	Cal correction factor in dB's calcdb = 20 log calcf (.CAL measurement only)
notused	80	char[12]	not used
range	92	float	Adc range/code
coupling	96	couplingtype	Adc coupling

Measurement Table
Measurement Data

Offset from the beginning of the file: 652 bytes. The 256,000­byte Measurement Data 'msmdata' field consists of the following:

Variable	Offset	Type	Description
msmdata	0	Complex[n]	Calibrated Measurement Data (up to 256,000 bytes) where n = number of lines

For calibration measurements, the data is normalized, i.e., SQRT(msmdata.real [i]^2 + msdata.imag[i]^2) = 1, for each i.
Equivalently, real = cos(t), imag = sin (t), where t = arctan(imag/real).

MEASUREMENT TABLE
MEASUREMENT HEADER
ENUMERATED/ ENCODED DATA TYPES

Variables of the type 'datatype' describe the type of measurement and are enumerated as follows:

Value	Datatype	X-Axis	Y-Axis
0	Frequency Response	Frequency	Complex
1	Time Domain	Time	Real
2	Coherence	Frequency	Real
3*	Linear Spectrum	Frequency	Complex
4*	Impulse Response	Time	Real
5*	Auto Correlation	Time	Real
6*	Cross Correlation	Time	Real
7	Synthesized FRF Frequency	Frequency	Complex
8*	Curvefit FRF	Frequency	Complex
9*	Synthesized IRF	Time	Real
10*	- Not Specified	-	-
11*	Auto Spectrum Density	Frequency	Power/Hz
12	Auto Spectrum	Frequency	Power
13	Cross Spectrum	Frequency	Power
14*	Cross Spectrum Density	Frequency	Power/Hz
15	Calibration Data	Frequency	Complex
16*	Pressure Intensity Index	Frequency	Complex
17	Sound Pressure Level	Frequency	Real
18	Composite Sound Power	Frequency	Real
19	F1 Indicator	Frequency	Real
20	F2 Indicator	Frequency	Real
21	F3 Indicator	Frequency	Real
22	F4 Indicator	Frequency	Real
23	Intensity	Frequency	Real

* Not implemented yet.

MEASUREMENT TABLE
MEASUREMENT HEADER
MISCDATATYPE

Variables of type 'miscdatatype', are used to describe functions that do not fit into the standard supported datablock types. The variable 'miscdatatype' is encoded as follows:

Bits	Variable
0­1 2 3­5	Domain type Data type Domain unit type

The values of domain type are as follows:

Value	Domain
0	Time
1	Frequency
2	Volts

The enumerated values of data type are as follows:

Value	Type
0	Real
1	Complex

The enumerated values of domain unit type are as follows:

Value	Excitation
0	Linear
1	RMS
2	Power
3	PSD
4	ESD

MEASUREMENT TABLE
MEASUREMENT HEADER
WINDOWTYPE

Variables of type 'windowtype' are enumerated as follows:

Value	Datatype
0	User Defined
1	Rectangular
2	Hanning
3	Flattop, P301
4	Force
5	Exponential
6	Force chan 1/Exponential chan 2
7	Exponential chan 1/Force chan 2
8	Kaiser-Bessel
9	Harris-Blackman

If a user­defined window is specified, then the window identifier is entered in the string variable 'miscwindow'.

MEASUREMENT TABLE
HEADER SURFACETYPE

'Surfacetype' is an integer variable that designates the Measurement surfacetype for acoustic applications.


MEASUREMENT TABLE
MEASUREMENT HEADER
PEAKTYPE

Encoded character indicating the following:

Bit	Value
0	1=Peak, 0=RMS Hanning window compensation
1 - 2	1=Channel A, 2=Channel B (.APS measurements only)

MEASUREMENT TABLE
MEASUREMENT HEADER
XAXISRANGE
ZOOMTYPE

'Zoomtype' is enumerated as follows:

Value	Zoom
0	Baseband
1	Zoom
2	Full Octave
3	1/3 Octave
4*	1/6 Octave
5*	1/12 Octave
6*	1/24 Octave
7*	User (not implemented)

* not implemented

If Zoomtype equals 2,3,4,5, or 6 (Octave types):
­ xlow, xhigh, and deltax are not related to msmdata array directly.
- xlow and xhigh are valid data range.
- deltax = 0, if msmdata is acquired from octave analyzer.
- deltax > 0, if msmdata is derived from narrowband data and it equals delta frequency of narrowband data.
- index to msmdata array is ANSI octave band number minus one.

Example:
if zoomtype = 2 (full octave)
frequency for msmdata[0] is 2 (2^1) Hz and msmdata[13] is 16K (2^14) Hz.


if zoomtype = 3 (third octave)
frequency for msmdata[0] is 1.25 (2^1/3) hz and msmdata[42] is 20K (2^43/3) Hz.

- max number (band number) for msmdata depends on zoomtype.

Zoomtype		Maxband
2	Full Octave	14
3	1/3 Octave	43
4	1/6 Octave	(not implemented)
5	1/12 Octave	(not implemented)
6	1/24 Octave	(not implemented)

MEASUREMENT TABLE
MEASUREMENT HEADER
XAXISRANGE CODETYPE
The 'codetype' enumeration is analyzer dependent. It is currently used only for documentation purposes.

The encoded type ptdirtype variables include the point and direction information for the measurement. The number is computed as 10 · point number + direction.

MEASUREMENT TABLE
MEASUREMENT HEADER
CHANNEL 1/2
PTDIRTYPE

Direction information is enumerated as follows:

Value		Direction	Axis
0	No Direction
1	X	rectangular	global, local
2	Y	rectangular	global, local
3	Z	rectangular, cylindrical	global, local
4	R	cylindrical, spherical	global, local
5	T (Theta)	cylindrical, spherical	global, local
6	P (Phi)	spherical	global, local
7	Tx	rotation	rotation
8	Ty	rotation	rotation
9	Tz	rotation	rotation

Variables of ptdirtype are encoded as 10 · point number + direction. Examples are:

10Z	would be encoded as	(10 · 10) + 3 = 103 = 103
100 R	would be encoded as	(100· 10) + 4 = 1004 = 1004 = 1004
33 Tx	would be encoded as	(33 · 10) + 7 = 337
10 -X	would be encoded as	­(10 · 10) + 1 = ­101
38 -Tz	would be encoded as	­(38 · 10) + 9 ­389

MEASUREMENT TABLE
MEASUREMENT HEADER
CHANNEL 1 / 2
UNITSTYPE

' Unitstype' is enumerated as follows:

Value	Units	Lablel
0	user units	user defined
1	m/s^2	m/s^2
2	m/s	m/s
3	m	m
4	N	N
5	Pa (N/m^2)	Pa
6	N-m	N-m
7	g	g

Value	Units	Label
8	in/sec	ips
9	in	in
10	mils	mil
11	lbf	lbf
12	psi	psi
13	lbf-in	lbf-in
14	volts	volt

If user units are specified, then unit labels are entered in string variable 'unitslbl'.

MEASUREMENT TABLE
MEASUREMENT HEADER
CHANNEL 1/2
COUPLINGTYPE

Couplingtype is enumerated as follows:

Value	Coupling
0	DC
1	AC