SimTX API/Packets/StartMonitor

StartMonitor

Frame	ClientFrame, field 31
Member	start_monitor
Direction	Client → server
Session	Control, moderation
Roles	ROLE_CONTROL (authenticated), ROLE_MODERATION.
Permission	Control: the transmitter must belong to the account. Moderation: monitor.any.
Answered by	MonitorAck, then MonitorBlock frames, or Error
Answers
Defined in	control.proto

StartMonitor asks the server to stream the signal of a transmitter back to the client, so that an operator can hear what they are sending. The stream is the transmitter's complex baseband after the modulator and amplifier model, before the antenna and propagation.

Definition

message StartMonitor { bytes session_id = 1; int64 request_id = 2; }

Fields

#	Field	Type	Description
1	session_id	bytes	16-byte session id of the transmitter to monitor.
2	request_id	int64	Nonzero; echoed in the MonitorAck or Error.

Rules

• On a control session, the transmitter must belong to the same account as the control session. An anonymous control session cannot monitor anything. Authenticated control sessions need a control ticket, which the account service issues only to credentials with catalog.publish.
• On a moderation session, any transmitter may be monitored with monitor.any.
• Take session_id from the transmitter's own SessionStatus, or from a LiveSession.session_id in the StationList.
• Success: MonitorAck with active = true, then MonitorBlock frames. Failure: Error with NOT_FOUND (no live transmitter with that id) or FORBIDDEN (not yours).
• Not a heavy request. The stream starts with the newest samples; there is no backlog.

Examples

Complete frames, including the varint length prefix, from the protocol's golden test vectors (protocol/simtx/v25/testdata/frames.json).

start_monitor (client to server, 24 bytes):

17                     frame length 23
FA 01 14               start_monitor (StartMonitor), 20 bytes
  0A 10 AA AA AA AA …  session_id = aaaaaaaa-bbbb-4ccc-8ddd-eeeeeeeeeeee
  10 2C                request_id = 44

monitor_ack_started (server to client, 26 bytes):

19                     frame length 25
D2 02 16               monitor_ack (MonitorAck), 22 bytes
  08 2C                request_id = 44
  12 10 AA AA AA AA …  session_id = aaaaaaaa-bbbb-4ccc-8ddd-eeeeeeeeeeee
  18 01                active = true

See also

• Monitoring a transmitter