Remote Spectrum Monitoring System Help : Programming with SCPI : I/Q Capture Block Mode
 
I/Q Capture Block Mode
This mode captures a single block of IQ data. I/Q data is first stored to high speed DDR2 SDRAM buffer memory and then it can be saved to flash memory or sent to a remote user via Ethernet. The capture length (duration) is limited by the size of the buffer memory (256 Mbytes) and I/Q data rate, which is determined by the capture bandwidth.
The IQ capture bandwidth must be set to one of the available values listed in the table below. For each selectable bandwidth, the output data rate for a single I/Q data pair is listed in Table: IQ Capture Bandwidth Values. The output data rate does not change, regardless of bit resolution.
IQ Capture Bandwidth Values
I/Q Bandwidth
Output Data Rate MSPS
IQ Sample Pairs/Sec
20 MHz
76.25 / 3
25416666.67
13.3 MHz
76.25 / 4
19062500
6.67 MHz
76.25 / 8
9531250
2.67 MHz
76.25 / 20
3812500
1.33 MHz
76.25 / 40
1906250
667 kHz
76.25 / 80
953125
267 kHz
76.25 / 200
381250
133 kHz
76.25 / 400
190625
66.7 kHz
76.25 / 800
95312.5
26.7 kHz
76.25 / 2000
38125
13.3 kHz
76.25 / 4000
19062.5
The maximum capture length is limited by memory, capture bandwidth and bit resolution. Table: Maximum I/Q Block Capture Length shows the maximum capture length.
 
 
 
 
Maximum I/Q Block Capture Length
I/Q Bandwidth
24 bits
16 bits
10 bits
8 bits
20 MHz1
1.3
s
2.5
s
3.8
s
5.0
s
13.3 MHz
1.7
s
3.4
s
5.0
s
6.7
s
6.67 MHz
3.4
s
6.7
s
10.1
s
13.4
s
2.67 MHz
8.4
s
16.8
s
25.2
s
33.6
s
1.33 MHz
16.8
s
33.6
s
50.4
s
1.12
min
667 kHz
33.6
s
1.12
min
1.68
min
2.24
min
267 kHz
1.40
min
2.80
min
4.20
min
5.60
min
133 kHz
2.80
min
5.60
min
8.39
min
11.19
min
66.7 kHz
5.60
min
11.19
min
16.79
min
22.38
min
26.7 kHz
13.99
min
27.98
min
41.97
min
55.96
min
13.3 kHz
27.98
min
55.96
min
1.40
hr
1.87
hr
6.67 kHz
55.96
min
1.87
hr
2.80
hr
3.73
hr
2.67 kHz
2.33
hr
4.66
hr
6.99
hr
9.33
hr
1.33 kHz
4.66
hr
9.33
hr
13.99
hr
18.65
hr
1 For 20 MHz capture bandwidth, when IQ bit resolution is set to 32 bits, the lower 8 bits are zeros. Therefore the maximum effective bit resolution is 24 bits for 20 MHz bandwidth.