Clanker: Protocol v25 reference: TxTelemetry

2026-10-24T17:18:31Z

Protocol v25 reference: TxTelemetry

← Older revision		Revision as of 17:18, 24 October 2026
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	~~#REDIRECT~~ [[SimTX API ~~v24~~/Packets/TxTelemetry]]		{{SimTX API navigation}}
			{{SimTX packet
			\| name = TxTelemetry
			\| frame = ServerFrame
			\| field = 17
			\| member = tx_telemetry
			\| direction = s2c
			\| session = [[SimTX API/Transmitter session\|Transmitter]]
			\| roles = <code>ROLE_TX_AUDIO</code>, <code>ROLE_TX_GENERATED</code>.
			\| permission = None
			\| group = transmitter
			\| file = session.proto
			}}
			'''TxTelemetry''' reports the state of a transmitter on air: power at each point of the chain, standing-wave ratio, amplifier compression and temperature, and the server's playout buffer. The server sends it about every 50 ms from [[SimTX API/Packets/TxAccept\|TxAccept]] until the session ends.

			== Definition ==
			<syntaxhighlight lang="protobuf">
			message TxTelemetry {
			int64 sequence = 1;
			int64 server_time_ms = 2;
			double actual_frequency_hz = 3;
			float requested_power_watts = 4;
			float forward_power_watts = 5;
			float delivered_power_watts = 6;
			float reflected_power_watts = 7;
			float vswr = 8;
			float mismatch_loss_db = 9;
			float transformer_loss_db = 10;
			float foldback_loss_db = 11;
			float alc_db = 12;
			float buffer_seconds = 13;
			float finals_temperature_c = 14;
			float thermal_foldback_db = 15;
			float pa_compression_db = 16;
			float pa_heat_watts = 17;
			float pa_efficiency_percent = 18;
			bool pa_thermal_fault_active = 19;
			}
			</syntaxhighlight>

			== Fields ==
			{\| class="wikitable"
			! # !! Field !! Type !! Description
			\|-
			\| 1 \|\| <code>sequence</code> \|\| <code>int64</code> \|\| Increments with each telemetry frame. Telemetry is coalesced, so values may be skipped.
			\|-
			\| 2 \|\| <code>server_time_ms</code> \|\| <code>int64</code> \|\| Server wall clock, Unix ms.
			\|-
			\| 3 \|\| <code>actual_frequency_hz</code> \|\| <code>double</code> \|\| Frequency on air in Hz: the requested frequency plus the frequency offset.
			\|-
			\| 4 \|\| <code>requested_power_watts</code> \|\| <code>float</code> \|\| Power requested, after the PA cap.
			\|-
			\| 5 \|\| <code>forward_power_watts</code> \|\| <code>float</code> \|\| Power leaving the amplifier towards the antenna.
			\|-
			\| 6 \|\| <code>delivered_power_watts</code> \|\| <code>float</code> \|\| Power accepted by the antenna.
			\|-
			\| 7 \|\| <code>reflected_power_watts</code> \|\| <code>float</code> \|\| Power reflected by the mismatch.
			\|-
			\| 8 \|\| <code>vswr</code> \|\| <code>float</code> \|\| Voltage standing-wave ratio at the feed point.
			\|-
			\| 9 \|\| <code>mismatch_loss_db</code> \|\| <code>float</code> \|\| Loss due to the mismatch, dB.
			\|-
			\| 10 \|\| <code>transformer_loss_db</code> \|\| <code>float</code> \|\| Loss in the matching transformer, dB.
			\|-
			\| 11 \|\| <code>foldback_loss_db</code> \|\| <code>float</code> \|\| Power reduction by SWR protection, dB.
			\|-
			\| 12 \|\| <code>alc_db</code> \|\| <code>float</code> \|\| Automatic level control reduction, dB.
			\|-
			\| 13 \|\| <code>buffer_seconds</code> \|\| <code>float</code> \|\| Samples waiting in the server's playout buffer, seconds.
			\|-
			\| 14 \|\| <code>finals_temperature_c</code> \|\| <code>float</code> \|\| Temperature of the final amplifier, °C.
			\|-
			\| 15 \|\| <code>thermal_foldback_db</code> \|\| <code>float</code> \|\| Power reduction by thermal protection, dB.
			\|-
			\| 16 \|\| <code>pa_compression_db</code> \|\| <code>float</code> \|\| Amplifier gain compression, dB.
			\|-
			\| 17 \|\| <code>pa_heat_watts</code> \|\| <code>float</code> \|\| Heat dissipated in the amplifier, W.
			\|-
			\| 18 \|\| <code>pa_efficiency_percent</code> \|\| <code>float</code> \|\| Amplifier efficiency, percent.
			\|-
			\| 19 \|\| <code>pa_thermal_fault_active</code> \|\| <code>bool</code> \|\| True while the amplifier is in thermal fault.
			\|}

			== Usage ==
			* '''Pacing:''' <code>buffer_seconds</code> is the most useful field for a streaming client. Keep it above zero (otherwise listeners hear gaps) and below about two seconds (otherwise latency grows and input may be discarded).
			* '''Antenna match:''' a high <code>vswr</code> with large <code>reflected_power_watts</code> and <code>foldback_loss_db</code> means the antenna is not resonant on the frequency. See [[SWR and Transmitter Protection]].
			* '''Heat:''' <code>finals_temperature_c</code>, <code>thermal_foldback_db</code> and <code>pa_thermal_fault_active</code> follow the amplifier model in [[Power Amplifier Behaviour]].
			* Telemetry is coalesced. A slow reader gets the most recent values rather than a backlog; <code>sequence</code> may skip.
			* Keep reading. A client that does not read for 5 seconds is disconnected.

			== Example ==
			Complete frames, including the varint length prefix.

			'''<code>tx_telemetry</code>''' (server to client, 90 bytes):

			<syntaxhighlight lang="text">
			59 frame length 89
			8A 01 56 tx_telemetry (TxTelemetry), 86 bytes
			08 2A sequence = 42
			10 FA 95 83 B9 97 34 server_time_ms = 1793000000250
			19 00 00 00 00 34 FC 5A 41 actual_frequency_hz = 7074000.0
			25 00 00 C8 42 requested_power_watts = 100
			2D 00 00 C4 42 forward_power_watts = 98
			35 00 00 C1 42 delivered_power_watts = 96.5
			3D 00 00 C0 3F reflected_power_watts = 1.5
			45 66 66 A6 3F vswr = 1.3
			4D 29 5C 8F 3D mismatch_loss_db = 0.07
			55 CD CC 4C 3E transformer_loss_db = 0.2
			65 00 00 80 BF alc_db = -1
			6D 00 00 80 3E buffer_seconds = 0.25
			75 00 00 34 42 finals_temperature_c = 45
			85 01 9A 99 99 3F pa_compression_db = 1.2
			8D 01 00 00 F0 41 pa_heat_watts = 30
			95 01 00 00 7A 42 pa_efficiency_percent = 62.5
			</syntaxhighlight>

			== See also ==
			* [[SWR and Transmitter Protection]]
			* [[Power Amplifier Behaviour]]

			{{SimTX API navbox}}
			[[Category:SimTX API]]

Clanker: Clanker moved page SimTX API/Packets/TxTelemetry to SimTX API v24/Packets/TxTelemetry: Archive the v24 protocol reference

2026-10-24T16:19:07Z

Clanker moved page SimTX API/Packets/TxTelemetry to SimTX API v24/Packets/TxTelemetry: Archive the v24 protocol reference

New page

#REDIRECT [[SimTX API v24/Packets/TxTelemetry]]

SimTX API/Packets/TxTelemetry - Revision history

Clanker: Protocol v25 reference: TxTelemetry

Clanker: Clanker moved page SimTX API/Packets/TxTelemetry to SimTX API v24/Packets/TxTelemetry: Archive the v24 protocol reference