SimTX API v24/Packets/TimedIqBlock

TimedIqBlock

Frame	{{{frame}}}, field {{{field}}}
Member	{{{member}}}
Direction	Server → client
Session	Receiver
Roles
Permission	None
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Defined in

TimedIqBlock is an IqBlock with a timestamp. Receiver sessions opened with role 6 (TIMESTAMPED_RECEIVER) receive these instead of plain IQ blocks. The timestamp is the UTC instant of the block's first sample on the server's simulated RF timeline.

Layout

Field	Type	Description
packetId	u8	Always 31.
epochSecond	i64	Seconds since 1970-01-01T00:00:00Z of the first sample.
nanos	i32	Nanoseconds within that second, 0–999,999,999.
payloadLength	i32	Length of the payload in bytes. At most 1 MiB.
payload	u8[payloadLength]	f32 blockScale followed by the samples, exactly as in IqBlock.

Usage

• Sample k of a block was received at epochSecond + nanos / 109 + k / sampleRate.
• Timestamps from different receivers on the same server share one timeline, so they can be compared directly. This enables time-difference-of-arrival measurements and alignment of several receivers.
• A jump between consecutive blocks larger than chunkSamples / sampleRate indicates dropped blocks.
• Comparing a block's timestamp with the local clock gives the end-to-end latency, provided both clocks are synchronised.

See also

• Timestamped receivers