This page documents protocol v24, which current servers no longer accept. See
SimTX API for v25.
TimedIqBlock
| Packet ID
|
31(0x1F)
|
| Direction
|
Server → client
|
| Session
|
Receiver
|
| Body size
|
20 + chunkSamples × 4 bytes (INT16)
|
| Permission
|
None
|
| Answered by
|
|
| Answers
|
|
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.
| 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.
|
- 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.
