SimTX API/Packets/MonitorBlock

MonitorBlock

Frame	ServerFrame, field 31
Member	monitor_block
Direction	Server → client
Session	Control, moderation
Roles	ROLE_CONTROL, ROLE_MODERATION.
Permission	None
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Answers
Defined in	control.proto

MonitorBlock carries a block of a monitored transmitter's signal, as requested with StartMonitor. Blocks arrive in real time until MonitorEnd or StopMonitor.

Definition

message MonitorBlock {
  bytes session_id = 1;
  int32 sample_rate = 2;
  repeated float iq = 3;       // interleaved I, Q
}

Fields

#	Field	Type	Description
1	session_id	bytes	The monitored transmitter.
2	sample_rate	int32	Complex samples per second: the transmitter's processing rate.
3	iq	repeated float	Complex baseband, I and Q interleaved, centred on the carrier. At most 262,144 floats.

Usage

• Demodulate the IQ with the transmitter's modulation to hear the signal.
• sample_rate is the transmitter's processing rate: its declared sample rate, at least 240,000 for WFM, at most 10,000,000.
• Monitor blocks share the session's output queue, which holds at most 64 frames or 8 MiB. A client that cannot keep up has its connection closed. Read on a dedicated thread.
• A wideband transmitter produces a lot of data: 10 MS/s of complex floats is 80 MB/s.

See also

• StartMonitor