ITPSDFINAL

Processed power spectral density

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

The ITPSDFINAL log contains the samples for the spectral analysis. The rate and size is set by the update period and the FFT size respectively when issuing the ITSPECTRALANALYSIS command.

PSD samples are compressed into 2 byte samples to reduce log sizes. The range of values that can be displayed is -200 dBm to +56 dBm with a 1/256 resolution. The following steps should be performed on the PSD samples in this log to convert them back into dBm units for display purposes:

  1. Divide the sample by 256.0

  2. Subtract 200

The number of samples are calculated according to the following table. The maximum number of samples in one ITPSDFINAL log is 1024. That means if the number of samples is less than 1024, one log is enough to output them. However, if the number of samples is larger than 1024, more than one ITPSDFINAL log is needed. For example, in postdecimation mode with the FFT size of 8K and subcarrier integration of 5, there is one log with 1024 samples and another log with 614 samples. The output logs can be grouped together through the sequence number of the log header.

Data Source

Number of Samples

PREDECIMATION

FFTsize/(2*subcarrier_integration )

POSTDECIMATION

FFTsize/subcarrier_integration

POSTFILTER

FFTsize/subcarrier_integration

As the data rate for the ITPSDFINAL log is dictated by the updateperiod parameter in the ITSPECTRALANALYSIS command, do not use ONTIME to log this message. Instead use ONNEW to log ITPSDFINAL.

The pre-decimation spectrum shows the absolute power in dBm which is proportional to the resolution bandwidth (RBW). The post-decimation and post-filter spectrum shows the signal magnitude in relative power (dB).

To view the samples for the spectral analysis for the secondary antenna of dual antenna receivers (OEM7720, PwrPak7D, PwrPak7D-E1, PwrPak7D-E2 and CPT7), log ITPSDFINAL_1.

Message ID: 1968

Log Type: Asynch

Recommended Input:

log itpsdfinala onnew

ASCII Example

#ITPSDFINALA,UNKNOWN,0,66.0,FINESTEERING,1891,166978.221,02040000,b79a,32768;
1310752,1531.250,195312.500,512,28033,30370,30225,29190,27254,29521,32694,
33025,28553,28902,29060,26663,30267,30054,

34027,38038,31082,29418,28805,27373,27869,28847,28331,31901,30251,33625,33625
*000b928d

Field

Field Type

Description

Format

Binary Bytes

Binary Offset

1

ITPSDFINAL header

Log header. See Messages for more information.

-

H

0

2

status word

Status word containing information about the configuration of the spectral analysis (see Table: Spectral Analysis Status Word)

Ulong

4

H

3

frequency start

Frequency represented by first data sample (MHz)

Float

4

H+4

4

resolution bandwidth

The resolution bandwidth (Hz)

Float

4

H+8

5

# samples

Number of spectral density samples

Ulong

4

H+12

6

sample

Power spectral density sample

Ushort

2

H+16

7

Next sample = H+16+(2*#samples)

8

xxxx

32-bit CRC (ASCII and Binary only)

Ulong

4

H+16+
(2*#
samples)

9

[CR][LF]

Sentence terminator (ASCII only)

-

-

-

Spectral Analysis Status Word

Nibble

Bit

Mask

Description

Range Value

N0

0

0x00000001

Frequency

0 – 20

See Table: Frequency Types

1

0x00000002

2

0x00000004

3

0x00000008

N1

4

0x00000010

5

0x00000020

Data Source

0 – 3

See Table: Data Sources for PSD Samples

6

0x00000040

7

0x00000080

N2

8

0x00000100

FFT Size

0 – 6

See Table: FFT Sizes

9

0x00000200

10

0x00000400

11

0x00000800

Integration Window

1 – 1024 samples

N3

12

0x00001000

13

0x00002000

14

0x00004000

15

0x00008000

N4

16

0x00010000

17

0x00020000

Time Average Window

0 – 100 seconds

18

0x00040000

19

0x00080000

N5

20

0x00100000

21

0x00200000

22

0x00400000

23

0x00800000

N6

24

0x01000000

25

0x02000000

Reserved

26

0x04000000

27

0x08000000

N7

28

0x10000000

Reserved

29

0x20000000

30

0x40000000

31

0x80000000