3152B User Manual
Publication No. 980935 Rev. A
5-78 Programming Reference
EADS North America Test and Services
FM:MARKer <frequency>(?)
HS Syntax: 0079A<float>(?)
Description
This function programs marker frequency position. The FM marker can be placed within the following range:
(carrier frequency ± deviation frequency / 2). The marker pulse is output from the SYNC output connector.
Parameters
Name
Range
Type
Default
Description
<frequency>
10e-3 to
100e6
Numeric
1e6
Programs the marker frequency position in units of Hz.
Response
The 3152B returns the current marker frequency value.
FM:DATA#<header><binary_block>
HS Syntax: 00741#<string>
Description
This command downloads an FM modulation waveform to the arbitrary FM memory. Arbitrary modulation
waveform table data is downloaded to the 3152B using binary block transfer. Binary block transfer allows any
8-bit bytes (including extended ASCII code) to be transmitted in a message. Downloading data to the arbitrary
FM waveform memory differs from downloading arbitrary waveform data. Arbitrary waveform data is for the
time domain, therefore, every point programs an amplitude level. On the other hand, FM modulating waveform
data programs frequency domain therefore, every point sets different sample clock frequency.
FM:DATA#3100<binary_block>
This command causes the transfer of 10 bytes of data to the arbitrary FM waveform memory. The <header>
is interpreted this way:
•
The ASCII "#" ($23) designates the start of the binary data block.
•
"3" designates the number of digits that follow.
•
"100" is the number of bytes to follow. This number must divide by 4.
The generator accepts binary data as 32-bit integers, which are sent in five-byte words. Therefore, the total
number of bytes is always three times the number of arbitrary FM waveform points. For example, 100 bytes
are required to download 20 arbitrary FM waveform points. The IEEE-STD-488.2 definition of Definite
Length Arbitrary Block Data format is demonstrated in Figure 5-1 (refer to the TRACe subsystem). The
transfer of definite length arbitrary block data must terminate with the EOI bit set. This way, carriage-return
(CR – 0dH) and line feed (LF – 0aH) characters can be used as sequence data and will not cause
unexpected termination of the arbitrary block data.
Downloading data to the arbitrary FM waveform memory is very different than loading arbitrary waveform
data. Waveform data programs amplitude domain therefore, every point programs an amplitude level. On
the other hand, FM modulating waveform data programs frequency domain therefore, every point sets
different frequency. The FM modulating waveform data is made of 32-bit words. However, the GPIB link has
8 data bas lines and accepts 8-bit words only. Therefore, the data has to be prepared as 32-bit words and
rearranged as five 8-bit words before it can be used by the 3152B as FM modulating waveform data. Figure
5-8 shows how to prepare the 32-bit word for the FM modulating waveform.
There are a number of points you should be aware of before you start preparing the data:
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