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SOURce:SCENario:ADVLOG?

Function

The Advanced Log feature queries log records of the specified log. This feature is effective as of firmware version 6.7.1.

The following logs can be queried:

  • RSG log – contains realtime movement parameters of the object being modelled along with time information;
  • SAT log – contains various data describing modelled satellites movement parameters along with time.
  • NAVMSG log – contains navigation data messages transmitted by simulated satellite

Command Syntax

SOURce:SCENario:ADVLOG? <logID>[,<filter1>,<filter2>,...,
<filterN>]

<logID> – log identifier that specifies what log data to request

<filterX> – optional filter expression that allows to include into response only specified record types

Mechanism

When a scenario is running, the GSG unit internally creates log records at predefined time intervals and puts them into a limited-size queue with a FIFO (First In – First Out) structure where they remain for some time (several seconds). As the scenario continues to run, new records get added into the log and old records get removed either automatically or by request from the user. Each type of log features its own (independent) queue.

RSG log records are created every 100 ms. SAT log records are created every 1 second.

When requested using the sour:scen:advlog? command, log records are removed from the queue starting with the oldest available records. They are returned as text lines containing comma-separated fields. These lines can be easily processed by user-developed software to extract specific fields, or they can be stored in a csv-file allowing for further analysis with spreadsheet software.

When the user does not request any log records, the latest log records remain in their queues until the unit is requested to start a new scenario. Hence it is possible to get remaining records even after a scenario was stopped.

One possible approach to using the advanced log feature is to periodically make a series of repetitive queries, waiting for an empty response in each series. An empty response signifies that the most recent data have been received and no new data is available so far.

General response structure

A response to an advanced log command usually contains several lines of text, with each line containing several comma-separated fields. The order of these fields corresponds with the labels order in response to a SOURce:SCENario:ADVLOG:HEADER? query.

Each line of the response is terminated with the line end symbol “\n” (ASCII code 0x0A). Not all records may be returned at once, so another request may be required. If all records have been returned and no new records are available, an empty response will be returned. When SCPI raw mode is enabled, responses are additionally terminated with an empty line (containing only the newline symbol in it), even if no new records are available. The additional newline symbol is intended to simplify end of response detection on the TCP client side.

Since queue sizes are limited, it may be important to ensure that no record is missed due to queue overflow caused by too low a query rate. Log records of RSG and SAT logs contain the id field that can be used to detect such an “overflow condition”. The id field is a 16-bit unsigned counter that counts from 0 to 65535 and then wraps to 0.

Note that several consecutive lines may contain the same id field. That is because a group of records is usually created at the same moment, but may still contain different data sets. For example, a group of SAT log records usually contains information about several satellites, so there will be several lines of data – one per satellite, and each line will have the same record id and time fields. In the RSG log, movement parameters for the body center and the antenna are created at the same moment.

Filter expressions

Each log supports individual filter expressions. Several of them can be combined with commas to specify what record types should be included in the response. If no filter expression is specified, the return response will contain all supported record types.

For the RSG log the supported record types are:

BODY_CENTER
CENTER
CENT
Includes RSG parameters for body center
ANTENNA
ANT
Includes RSG parameters for antenna

Filter expressions example:

SOUR:SCEN:ADVLOG? RSG,BODY_CENTER
SOUR:SCEN:ADVLOG? RSG,CENTER,ANT

EXAMPLE:

SEND:

sour:scen:advlog? sat

READ:

17803, SAT, 17803.0, 2014-05-09T19:56:26.000, 503803.0, G9, 13999325.9529469125, -21451840.2281696014, -7614347.5806083838, 23965993.35, -269.19, 1414.63, -0.37