Packet.Radio 0.23.0

Packet.Radio

The radio-control abstraction for Packet.NET — what a serial control channel to the radio behind the modem adds to a packet link, expressed protocol-neutrally.

Standard KISS gives you demodulated frames and nothing else. A radio with a control channel (Tait CCDI, Yaesu CAT, ICOM CI-V, …) can also report signal strength, tell you the moment the channel goes busy, and key its transmitter — and this package is the driver-neutral seam that surfaces those to the AX.25 stack. It is the base contract the concrete drivers implement (see Packet.Radio.Tait); applications code against the interfaces here. Part of Packet.NET, a .NET amateur-radio / AX.25 packet stack.

Install

dotnet add package Packet.Radio

What a control channel gives you that raw KISS can't

• RSSI in dBm — attribute signal strength (and SNR against a tracked noise floor) to every received frame.
• Hardware carrier-sense (DCD) — the channel is busy now, typically 0.5–1 s before the modem finishes demodulating the frame on air: exactly the head start CSMA wants.
• Transmitter keying — PTT under software control, independent of the modem's PTT line.
• A radio-native side channel — small control datagrams that bypass the audio modem entirely, so they keep working while the link they sit beside is being reconfigured.

Types

• IRadioControl — the capability-probed contract: ReadRssiDbmAsync, SetTransmitterAsync, ChannelBusy + CarrierSenseChanged, and a RadioCapabilities flags enum. Drivers advertise only what their radio/firmware actually supports; reserved flags (channel change, frequency, TX power) exist so richer radios can be described before the interface grows those members.
• RssiTaggingTransport — an IAx25Transport decorator: a background sampler polls RSSI (fast while the channel is busy, slow while idle so the idle samples track the noise floor) and re-yields every inbound frame with Ax25InboundFrame.Radio populated — RSSI median/min/max/sample-count, SNR, noise floor, carrier-rise instant, burst index (an AX.25 frame train shares one carrier), airtime estimate, and — for the first frame of a burst — the measured pre-data carrier time, the sender's effective TXDELAY (an excess-TXDELAY detector input). Frames with no qualifying sample get null metadata, never a guess.
• RadioCarrierSense — CSMA by hardware DCD, done natively by the AX.25 stack: bridges the radio's ChannelBusy onto the neutral ICarrierSense seam (Packet.Ax25.Transport.Abstractions) that Ax25Listener consults before every keyup (via the Ax25ListenerOptions.CarrierSense option). The listener's own CarrierSenseGate holds the keyup while the channel is busy (bounded wait, fail-open) — the medium-access deferral lives in the stack, not an opaque transport wrapper, and composes with the TNC's own persistence CSMA.
• RigRadioControl — the rig→radio bridge: surfaces a CAT rig (Packet.Rig's IRigControl — hamlib rigctld, flrig) as this package's IRadioControl, so a CAT transceiver feeds the same CSMA gate and per-frame-RSSI machinery a push-capable radio does. Capabilities map at construction (DcdRead → CarrierSense, SignalStrengthRead → RssiRead, PttSet → TransmitterControl); a rig offering none of the three is rejected. Rig backends are poll-only, so carrier-sense edges are synthesized by an owned DCD poll loop (100 ms default) — edges shorter than the poll interval are invisible, coarser than a true push source. A failed read fails open (ChannelBusy = null) and backs off to a slower retry cadence until the backend self-heals. ownsRig: true hands the rig's lifetime to the adapter (dispose stops polling, then disposes the rig); the default false leaves the rig with the caller, and dispose best-effort unkeys anything the adapter left keyed.
• IRadioSideChannel — a small-datagram control plane the radio itself provides (e.g. Tait SDM over the radios' internal FFSK modem): SendAsync / ReadBufferedAsync short payloads with over-air delivery receipts and a MaxPayloadLength budget. Because it bypasses the audio modem it is mode/deviation/channel-width-agnostic — the coordination channel for renegotiating the very link it sits beside (mode agility, remote tuning). Drivers advertise the machinery via RadioCapabilities.SideChannel; consumers must still probe that it is enabled in the radio's programming before gating features on it.

Usage

await using var radio = TaitCcdiRadio.Open("/dev/ttyUSB0");   // from Packet.Radio.Tait
await radio.SetProgressMessagesAsync(true);                   // turn on DCD events

await using var tnc = NinoTncSerialPort.Open("/dev/ttyACM1"); // from Packet.Kiss.NinoTnc
await using var tagged = new RssiTaggingTransport(tnc, radio);

await foreach (var frame in tagged.ReceiveAsync(ct))
{
    // frame.Radio?.RssiDbm / frame.Radio?.SnrDb now populated
}

With carrier-sense, frames are attributed to the transmission window that contains their arrival; without it, RssiTaggingTransport falls back to a threshold-over-noise-floor filter and the window-derived fields (carrier-rise, burst index, pre-data carrier) stay null. NoiseFloorDbm exposes the live idle-sample estimate. Both decorators leave ownership of the inner transport and the radio with the caller — disposing the decorator only stops its sampler/gate.

See also

• Source & issues
• Packet.Radio.Tait — the Tait TM8100/TM8200 CCDI implementation of this contract
• Packet.Tune.Core — link-tuning + mode coordination over IRadioSideChannel
• Packet.Kiss.NinoTnc — the NinoTNC IAx25Transport these decorators wrap

Status: experimental — the IRadioControl shape is plan OQ-011's proposed common subset {RSSI-get, busy-get, PTT-set} and may move as second/third implementations (Yaesu CAT, ICOM CI-V) land.