This section describes the factors for calculating the byte size of responses to selected remote-only queries. The byte size of the resultant data from several of the remote only queries depends on several factors:
• Parameters per Output
• Numbers Output per Data Point
• Bytes Output per Number
• Size of Block Data
• Number of Bytes Output
Numbers Output-per-Data Point (NODP)
The data for each data point is a complex number (A + jB) where A and B are floating point numbers. This data is saved internally for use and possible future output. Additionally, if an RF correction is active, the RF correction is applied to the RAW measurement and the result is saved internally for use and possible future output. Either the RAW or CORRECTED data are taken and converted into the data format for the display type selected.
This data is saved internally in the FORMATTED (final) measurement form for use and possible future output. When this conversion takes place, the data will, in most cases, still be two orthogonal numbers. However, several of the displays types throw away a portion of the data and the result will be one number only. The display types that produce only one number are:
• Group Delay
• Imaginary
• Linear Magnitude
• Log Magnitude
• Phase
• Power Out
• Real
• SWR
To summarize, the RAW, CORRECTED, and FORMATTED data output will be two numbers-per-point, unless the display type is one of those mentioned above.
Bytes Output-per-Number (BOPN)
The number of bytes output per number is shown below:
Bytes Output per Number
Number
Output Format
Output-per-Number
FMA
(ASCII)
14 plus comma (short form data) 19 plus comma (long form data)
FMB
(double precision binary)
8
FMC
(single precision binary)
4
Size of Data Block (SODB)
In the case where there is only one parameter to output, the formula is:
SODB = NODP * BOPN * Number of points in the sweep
If the command is O4SC, O4FD, or O4SR, the formula is:
SODB = 8 * BOPN * Number of points in the sweep
Number of Bytes Output (NBO)
The number of bytes output is the number of bytes transmitted over the GPIB. In most cases, the data block is proceeded by an arbitrary block header followed by an end character (line feed), as shown below:
The size of the end character is one byte. The size of the arbitrary block header is variable between 2 and 11. If we always assume an arbitrary block header size of 11, then: NBO = 12 + SODB. For example:
• The VNA is set up for a one channel, four-trace display with a 1601 point sweep.
• Trace 1 is displaying S11 in LogMag and Phase format
• Trace 2 is displaying S12 in LogMag format
• Trace 3 is displaying S21 in Phase format
• Trace 4 is displaying S22 in Smith Chart format
• The output formatting commands CH2, FMC, and LSB are received
The number of output bytes for the O4FD query command is:
NBO = 12 + 8 * 4 * 1601 = 51244 bytes
The number of output bytes for the ORD query command is:
NBO = 12 + 2 * 4 * 1601 = 12820 bytes
The number of output bytes for the OFD3 query command is:
NBO = 12 + 1 * 4 * 1601 = 6416 bytes
The number of output bytes for the FMA or O4SR query command is: