Creating a Recording

You can create a recording of time data from any real "baseband" or complex (I +jQ) "zoom" measurement. When you create a recording, the VSA acquires a time record from the Analyzer Configuration as if performing a measurement but instead saves the data to a temporary recording file. This temporary file can then be played back through the VSA or saved to disk.

Trigger parameters affect the outcome of the time record capture from hardware when creating a recording as well as when making a measurement.

The basic steps to create a signal recording are very simple:

Set up the desired VSA measurement.
Configure triggering.
Configure the Recording parameters (Input > Recording...): Record Length, Max Length, and Extra to settle.

The default values will support most typical measurements, see the Recording Setup section for more information.
Start the signal recording by clicking the Record button.

There are three available VSA start recording controls:
- Control > Record menu item
- Record button on the Record toolbar
- Record button on the Player (Window > Player)
When you click Record, the VSA acquires the time record from the Analyzer Configuration, creates a temporary recorded signal file, changes the Input data source from Hardware to Recording (Input > Data From > Recording), and starts the measurement so that you can see what you just recorded.
Save the Temporary signal recording as a permanent file.

The VSA stores the signal recording to a temporary file. If you want to save the signal recording for future playback and analysis, manually save the signal as a recording, click File > Save > Save Recording... and select the "Save header with data" Save Option. If you need this recording for source signal playback, you need to save the file as a MATLAB "*.mat" formatted file. See Saving a Recording.

Recordings are saved in a temporary recording file which is overwritten when a new recording is created or a recording is recalled. To preserve the current recording, save the temporary recording file before creating or recalling a recording.

Open the recording Player (Windows > Player), the player makes recording and playing back recordings easier to control and manipulate.

You can download and playback recordings through a source, see Source Signal Playback

Signal Recording Setup

Before starting a recording, configure the Record parameters to correctly capture and record the signal of interest. Open the Record tab (Input > Recording) to access the record setup properties.

Specifying the "Record Length" in seconds

Always verify that the Record Length parameter is specified to include all time data of interest. As a minimum, you need to specify a recording length that is long enough to acquire enough time data to successfully perform one single measurement sweep.

When averaging is OFF, the minimum recording length is equal to the time necessary to complete one single sweep measurement.
When averaging is ON, the minimum recording length is equal to the accumulated time data necessary to complete "n" (number of averages) single sweep measurements ("n" X "time to complete one single sweep measurement").

Specify Record Length in "records"

You can specify Record Length in seconds, points, or records. It is simpler and less error prone to specify the Record Length in units of "records". The VSA defines one "record" as equal to the minimum record length time necessary to acquire enough time data to complete one single measurement sweep . Therefore, the minimum Record Length necessary to successfully replay a recorded single sweep measurement is one "record" long. A typical recording acquires more than the minimum one "record" length of time data.

The default record Record Length is 50 records, this default recording length is satisfactory for most typical measurement scenarios. The minimum Record Length value of 1 record is required to successfully replay a recorded measurement. A Record Length value of zero or less will be reset to a default value of 10 records.

A recording length of less than 1 record is allowed but may result in playback errors. A small record length may not contain enough data points to fill one time record which is necessary to perform a measurement. This condition will cause a "Recording not long enough for current measurement" error message.

You can specify a Record Length greater than the hardware's maximum supported length, but the actual recording length will be truncated to the maximum. The actual recording length is shown next to the Record Length text box.

Specifying the "Max Length"

The maximum record length that can be specified is limited by the sample memory size (sometimes called capture RAM) of the measurement hardware front-end. The VSA provides a "Max Length" record property that, when selected, automatically sets the Record Length to the largest record length allowable for the current measurement hardware front-end. If you want to capture the maximum amount of signal time data, select the Max Length property; however, this may result in longer than necessary data acquisition times, increased file sizes, and acquiring more time data than required to successfully replay the measurement.

Temporary Recorded Files

New recorded signals are temporary files saved as ".sdf"-formatted files. The temporary file is overwritten every time a new recording is created or recalled. To save a temporary recording for future playback, click File > Save > Save Recording. To replay an existing recorded signal file, click File > Recall > Recall Recording.

There may be more than one temporary recording file saved in the default recording folder. A separate temporary recording file is created for each running instances of the VSA software and for each measurement type in a multiple measurement instance of the VSA.