7. Subject Area Model (APP 408)

7.1 Subject Areas

ClientSession
  owns WebSocket memberships and UI state

RadioControl
  owns CAT serial command state: frequency, mode, PTT, gains, filter

ScopeSystem
  owns FT4222 SPI data intake + S-meter fallback generation

AudioSystem
  owns PyAudio capture/playback, Opus codec, WS audio fan-out

SpectrumDisplay
  owns FFT data, waterfall rendering, S-meter smoothing, frequency scale

RadioState
  owns all mirrored radio state with dirty-field change tracking

PollingSystem
  owns 7-task adaptive background polling cadence

OperationalConfig
  owns serial port, web port, auth, host/port config

7.2 Entity Definitions

Entity	Attributes	Description
ClientSession	websocket, channel_type, connected_at	Runtime connection in `ctrl_clients`, `spectrum_clients`, `audio_rx_clients`, `audio_tx_clients`
RadioConnection	serial_port, baudrate, connected, model_id	CAT serial port state within `CatController`
RadioState	vfo_a_freq, vfo_b_freq, active_vfo, mode, tx_status, s_meter, af_gain, rf_gain, rf_power, filter_width, preamp, attenuator, noise_blanker, noise_reduction, auto_notch, compressor, compressor_level, nr_level, nb_level, tuner_status, power_on, squelch, mic_gain, split, vox, break_in, comp_meter, alc_meter, power_meter, swr_meter, id_meter, vd_meter, scope_span, scope_speed, scope_mode, scope_start_freq, serial_connected	Dataclass with dirty-field tracking
CatCommand	prefix, value, response	Serial CAT command: send `"FA014200000;"` → receive `"FA014200000;"`
ScopeFrame	wf1[850], wf2[850], s_meter, vfoa_freq, mode, scope_span, scope_mode, preamp, attenuator, scope_start_freq	Parsed from scope_pipe stdout payload
SpectrumFrame	version_byte, wf1_bytes[850], wf2_bytes[850]	Binary frame broadcast via `/WSspectrum`
AudioChunk	pcm_bytes, sample_count, timestamp	Raw Int16 PCM from PyAudio capture
AudioFrame	tag_byte, payload_bytes	Tagged dual-codec frame (0x00=PCM, 0x01=Opus) broadcast via `/WSaudioRX`
OpusEncoder	bitrate, frame_size, cap_bytes	Server-side libopus encoder via ctypes
OpusDecoder	sample_rate, channels	WASM Opus decoder in browser
PollTier	interval, commands, fields	One tier of the 7-task polling scheduler
MemoryChannel	index, frequency, mode, label	Memory record persisted in `mem_channels.json`
AuthToken	token_hex, created_at	32-byte random hex session token
SCOPE_PIPE_Process	pid, stdout, stderr	Subprocess running `scope_pipe.py` for FT4222 SPI I/O

7.3 Relationships

Relationship	Cardinality	Description
ClientSession → RadioState	N:1	Multiple browsers see same state via broadcast
CatCommand → RadioState	1:1	Each CAT response updates one or more state fields
ScopeFrame → SpectrumFrame	1:1	Each parsed scope frame produces one spectrum frame
AudioChunk → AudioFrame	1:N	One PCM chunk may produce multiple Opus frames (20ms boundaries)
RadioState → ClientSession	1:N	Dirty-field state updates fan out to all ctrl_clients
PollTier → CatCommand	1:N	Each tier sends multiple CAT queries per cycle

7.4 State Ownership

State	Owner	Persistence
Connected WebSockets	`server.py` global sets	Runtime only
Radio state	`RadioState` dataclass	Runtime only
CAT connection	`CatController` instance	Runtime only
Scope data	`ScopeHandler` instance	Runtime only
Audio streams	`AudioHandler` instance	Runtime only
Poll schedule	`PollScheduler` instance	Runtime only
Memory channels	`/api/mem_channels` + `mem_channels.json`	Filesystem (JSON)
Auth tokens	`_auth_tokens` set	Runtime only (cleared on restart)
UI state	`radioState` object, DOM	Browser session/cookies
Waterfall pixels	Canvas image data	Browser runtime only