Here are the classes, structs, unions and interfaces with brief descriptions:

[detail level 123]

Ntinymodem	TinyModem: software audio modems and packets with error correction
CAX25Config	Configuration of the AX.25 packet radio modem (AX25Encoder, AX25Decoder): Bell 202 AFSK with 1200 baud, NRZI and HDLC framing, as used by APRS
CAX25Frame	Conversion between AX.25 frames and the monitor text format (SRC>DEST,DIGI1,DIGI2*:info) and the KISS framing
CAX25Decoder	AX.25 packet radio demodulator (APRS, 1200 baud AFSK). The PCM audio data is written to the decoder and the received frames with a correct frame check sequence are written to the output: as monitor text lines (SRC>DEST,DIGI:info) or as KISS frames (see AX25Config::format)
CPhasor	Rotating phasor of a tone: avoids sin() and cos() per sample
CAX25Encoder	AX.25 packet radio modulator (APRS, 1200 baud AFSK). The written data is converted to AX.25 frames, which are sent with HDLC framing (flags, bit stuffing, frame check sequence) and NRZI coding
CFX25	FX.25: AX.25 frames with Reed-Solomon forward error correction (as implemented by direwolf). The complete HDLC frame (flag, bit stuffed frame with FCS, flags as fill) is the data part of a Reed-Solomon code word, which is preceded by a 64 bit correlation tag that identifies the code. A receiver without FX.25 still decodes the HDLC frame in the data part
CTag	Code (correlation tag)
CIL2P	IL2P (Improved Layer 2 Protocol, as implemented by direwolf): an AX.25 frame is sent as a scrambled header with Reed-Solomon parity and a scrambled payload in Reed-Solomon blocks, without HDLC framing and NRZI. Header type 1 compresses the addresses and the control field of frames with 2 addresses, header type 0 carries the complete AX.25 frame as payload
CBlocks	Partitioning of the payload into Reed-Solomon blocks
CCSSConfig	Configuration of the chirp spread spectrum modem (CSSEncoder, CSSDecoder), which works like LoRa in the audio band: each symbol is a linear chirp over the bandwidth, which starts at one of N = 2^SF frequencies and carries SF bits (SF = spreading factor). The signal can be received far below the noise level and is robust against frequency offsets, different clocks and echoes. It is not compatible with LoRa radios
CCSSFrame	Frame format of the chirp spread spectrum modem: the bytes of the header code word (length and parity) and of the payload code word (data, CRC-16 and parity) are sent as SF bits per symbol, most significant bit first. The symbol value is the inverse Gray code of the bits, so that a detection in the neighboring FFT bin causes only 1 wrong bit
CCSSDecoder	Chirp spread spectrum demodulator (LoRa-like): the PCM audio data is written to the decoder and the payload of the received frames with a correct CRC is written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only CSSConfig::channel is evaluated)
CPeak	Peak of a spectrum
CCSSEncoder	Chirp spread spectrum modulator (LoRa-like): the written bytes are collected and sent as frame when CSSConfig::max_frame bytes are available or when you call endTransmission() (or flush()). A frame consists of the preamble (up chirps), 2 down chirps, the header and the payload. Each symbol is a chirp which starts at the frequency of its value and wraps around at the end of the band. The phase is continuous
CDataCodec	Converts between characters and the data bits of a frame
CAsciiCodec	ASCII 8-bit data (passthrough)
CBinaryCodec	Raw N-bit binary data: prints the bits as '0' and '1' followed by newline
CBaudotCodec	Baudot (ITA2) 5-bit data
CCallerIDCodec	Caller-ID (USA SDMF/MDMF) decoder. See http://melabs.com/resources/callerid.htm
CUICCodec	UIC-751-3 ground-train or train-ground decoder
CMessage	UIC message code and its meaning
CPrintFilter	Print which replaces non printable characters with '.'
CSampleRateConverter	Converts the sample rate of a signal with a windowed sinc low pass filter (by default the cut off is at 45% of the lower sample rate)
CSimpleFFT	Radix 2 complex FFT with a precomputed twiddle table
CDTMFConfig	Configuration of the DTMF (touch tone) modem (DTMFEncoder, DTMFDecoder): each of the characters 0-9, *, #, A, B, C and D is sent as the sum of a row tone (697 - 941 Hz) and a column tone (1209 - 1633 Hz)
CDTMFKeys	The DTMF keypad: the tones and the characters of the 16 keys
CDTMFDecoder	DTMF (touch tone) demodulator: the PCM audio data is written to the decoder and the received keys (0-9, *, #, A-D) are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only DTMFConfig::channel is evaluated)
CWindow	Goertzel filters of one window
CDTMFEncoder	DTMF (touch tone) modulator: each written character 0-9, *, #, A-D (also a-d) is sent as a tone pair of DTMFConfig::tone_ms followed by a pause of DTMFConfig::pause_ms. A ',' adds a pause of DTMFConfig::comma_ms, all other characters are ignored. The tones fade in and out within 2 ms to avoid clicks
CFSKDecoder	FSK demodulator: PCM audio data is written to the decoder and the decoded data is written to the output that was defined with setOutput(). Supported input formats are 8, 16 or 32 bit signed integer samples with any number of channels (only config.channel is evaluated). The decoding is compatible with minimodem –tx
CFSKDemodulator	FSK bit and frame analysis (port of minimodem's fsk.c). Instead of a full FFT we use the Goertzel algorithm from the AudioTools to determine the magnitude of the mark and space bands. The bands are defined like the FFT bins of minimodem, so the results are equivalent
CFSKEncoder	FSK modulator: converts the written characters into 16 bit PCM audio which is written to the defined output. The generated signal is compatible with minimodem –rx
CGGWaveProtocol	Transmission protocol of ggwave (https://github.com/ggerganov/ggwave): the ids and parameters are identical to the original. The tones are multiples of sample_rate / samplesPerFrame (46.875 Hz at 48 kHz)
CGGWaveConfig	Configuration of the ggwave compatible modem (GGWaveEncoder, GGWaveDecoder). Each message (up to 140 bytes) starts and ends with a marker and is protected by Reed-Solomon codes. Each byte is sent as 2 of 16 tones which are transmitted at the same time
CGGWaveDecoder	Ggwave compatible demodulator: the PCM audio data is written to the decoder and the payload of the received messages is written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only GGWaveConfig::channel is evaluated)
CCandidate	Decoder for one protocol and timing offset
CGGWaveEncoder	Ggwave compatible modulator: the written bytes are collected into messages of up to 140 bytes. A message is sent when it is full or when you call endTransmission() (or flush()). The generated audio is identical to the audio of ggwave (variable length format)
CTone	Tone: FFT bin relative to freq_start and index of the phase offset
CMFSKConfig	Configuration of the multi-tone FSK modem (MFSKEncoder, MFSKDecoder). Each symbol is one of tones tones and carries log2(tones) bits. The tones are base_freq + i * tone_spacing
CMFSKDecoder	Multi-tone FSK demodulator: PCM audio data is written to the decoder and the decoded bytes are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only MFSKConfig::channel is evaluated)
CMFSKEncoder	Multi-tone FSK modulator: converts the written bytes into 16 bit PCM audio. Each symbol is one of MFSKConfig::tones tones and carries log2(tones) bits (Gray coded, most significant bit first)
CFSKToneGenerator	Default sine generator of the encoders: like minimodem it keeps the phase continuous when the frequency is changed (continuous phase FSK) and restarts it at phase 0 after silence (frequency 0)
CToneOutput	Writes tones of a SoundGenerator as 16 bit PCM with the requested number of channels and volume to a Print
CSampleOutput	Writes float samples (-1.0 to 1.0) as 16 bit PCM with the requested number of channels and volume to a Print
CPcmInput	Assembles the PCM frames from the written bytes and provides the samples of the selected channel as float (-1.0 to 1.0). Supports 8, 16 and 32 bit signed samples
CByteQueue	FIFO for received data which grows when needed: e.g. one decoding step can produce more data than expected (like a Caller-ID message)
CModemEncoder	Common API of the modulators (FSKEncoder, MFSKEncoder): the written data is converted to 16 bit PCM audio which is written to the output
CModemDecoder	Common API of the demodulators (FSKDecoder, MFSKDecoder): PCM audio data is written to the decoder and the decoded data is written to the output. Status messages (### CARRIER and ### NOCARRIER) are written to the status output
CModemConfig	Configuration of the FSK modem. The fields correspond to the command line options of minimodem. Call setMode() to select one of the predefined baud modes ("1200", "300", "rtty", "tdd", "same", "callerid", "uic-train", "uic-ground", "V.21" or any number N for a Bell-like N bps modem) first and then change the individual fields. Fields which are left at 0 (or -1) are derived automatically when the encoder or decoder is started
CBasicModemStream	Arduino Stream API for a modem (encoder and decoder): the written characters are modulated to the audio output and the audio input is demodulated into characters that can be read. You can use only the output (transmit only), only the input (receive only) or both
CModemStream	Arduino Stream API for the minimodem compatible FSK modem: print() transmits, read() receives. See BasicModemStream
CMFSKStream	Arduino Stream API for the multi-tone FSK modem: print() transmits, read() receives. See BasicModemStream
CAX25Stream	Arduino Stream API for the AX.25 packet radio modem (APRS): print() transmits the frames, read() provides the received frames, both as monitor text lines or KISS frames. See BasicModemStream
CPSKStream	Arduino Stream API for the PSK modem (PSK31 to PSK500): print() transmits, read() receives. See BasicModemStream
COFDMStream	Arduino Stream API for the OFDM modem: print() collects the data, flush() sends it as frame, read() receives. See BasicModemStream
CGGWaveStream	Arduino Stream API for the ggwave compatible modem: print() collects the data (up to 140 bytes), flush() sends it as message, read() receives. See BasicModemStream
COliviaStream	Arduino Stream API for the Olivia and Contestia modems (compatible with fldigi): print() transmits, flush() completes the last block, read() receives. See BasicModemStream
CCSSStream	Arduino Stream API for the chirp spread spectrum modem (LoRa-like): print() collects the data, flush() sends it as frame, read() receives. See BasicModemStream
CMorseStream	Arduino Stream API for Morse code (International or American): print() transmits, read() receives. See BasicModemStream
CDTMFStream	Arduino Stream API for the DTMF (touch tone) modem: print() sends the keys 0-9, *, #, A-D, read() provides the received keys. See BasicModemStream
CBasicModemStreamRTOS	BasicModemStream which receives in a separate task (FreeRTOS on ESP32 and RP2040, a std::thread on the desktop): the task reads the audio input and decodes it, so the decoding does not block your loop() and no audio is lost while loop() is busy. available(), read() and peek() only access the received data and can be called from any task
CLockedQueue	Print which writes the decoded data into the queue with a lock
CModemStreamRTOS	ModemStream (FSK) which receives in a separate task. See BasicModemStreamRTOS
CMFSKStreamRTOS	MFSKStream (multi-tone FSK) which receives in a separate task. See BasicModemStreamRTOS
CAX25StreamRTOS	AX25Stream (APRS) which receives in a separate task. See BasicModemStreamRTOS
CPSKStreamRTOS	PSKStream which receives in a separate task. See BasicModemStreamRTOS
COFDMStreamRTOS	OFDMStream which receives in a separate task. See BasicModemStreamRTOS
CGGWaveStreamRTOS	GGWaveStream which receives in a separate task. See BasicModemStreamRTOS
COliviaStreamRTOS	OliviaStream which receives in a separate task. See BasicModemStreamRTOS
CCSSStreamRTOS	CSSStream which receives in a separate task. See BasicModemStreamRTOS
CMorseStreamRTOS	MorseStream which receives in a separate task. See BasicModemStreamRTOS
CDTMFStreamRTOS	DTMFStream which receives in a separate task. See BasicModemStreamRTOS
CMorseConfig	Configuration of the Morse code modem (MorseEncoder, MorseDecoder): a tone which is switched on and off (CW). The speed is defined in words per minute (PARIS): a unit (the length of a dot) is 1.2 / wpm seconds
CMorseCode	The Morse code tables and timing. A code is a string of '.' (dot), '-' (dash), '_' (long dash of the American L), '=' (longer dash of the American 0) and ' ' (space within a character of American Morse)
CTiming	Lengths in units
CEntry
CMorseDecoder	Morse code demodulator (CW): the PCM audio data is written to the decoder and the decoded characters (upper case) are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only MorseConfig::channel is evaluated)
CMorseEncoder	Morse code modulator (CW): each written character is sent as dots and dashes of a tone with the timing of the alphabet (International: dot 1, dash 3, element space 1, letter space 3, word space 7 units). A space (or a character which is not in the alphabet) is a word space. The tone is switched on and off with a raised cosine ramp of MorseConfig::ramp_ms
COFDMConfig	Configuration of the OFDM modem (OFDMEncoder, OFDMDecoder): the data is transmitted in parallel on carriers subcarriers with differential QPSK (2 bits per carrier and symbol). Each symbol has a cyclic prefix (guard interval) against echoes
COFDMTable	Sine and cosine of 2 * PI * i / size
COFDMDecoder	OFDM demodulator: the PCM audio data is written to the decoder and the decoded frames are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only OFDMConfig::channel is evaluated)
COFDMEncoder	OFDM modulator: the written bytes are collected into frames (up to OFDMConfig::max_frame bytes) which are transmitted with differential QPSK on all carriers. A frame is sent when it is full or when you call endTransmission() (or flush())
COliviaConfig	Configuration of the Olivia and Contestia modems (OliviaEncoder, OliviaDecoder): MFSK with 2 to 256 tones and a strong forward error correction (Walsh-Hadamard codes over blocks of 64 or 32 symbols), as designed by Pawel Jalocha and implemented by fldigi
COliviaCodec	The forward error correction of Olivia and Contestia (as in fldigi): each character of a block of bitsPerSymbol() characters is a Walsh-Hadamard code word of 64 (Contestia: 32) bits, which is scrambled and spread diagonally over the 64 (32) symbols of the block
COliviaDecoder	Olivia and Contestia demodulator (compatible with fldigi): the PCM audio data is written to the decoder and the decoded characters are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only OliviaConfig::channel is evaluated)
COliviaEncoder	Olivia and Contestia modulator (compatible with fldigi): the written characters are collected in blocks of bitsPerSymbol() characters, which are FEC encoded into 64 (Contestia: 32) symbols. Each symbol is a tone with a raised cosine envelope over two symbol periods, so consecutive symbols overlap by half
CPacketStatistics	Statistics of the received packets
CPacketFormat	Constants of the packet format
CPacketEncoder	Splits the written data into packets with a CRC-16 and Reed-Solomon forward error correction, which are framed with HDLC-style flags (0x7E) and byte stuffing, and writes them to the output (e.g. a ModemStream)
CPacketDecoder	Receives the packets of a PacketEncoder: the written bytes (e.g. the output of a modem decoder) are deframed, corrected and checked, and the payload of the valid packets is written to the output
CPacketStream	Reliable data transfer over any Stream (e.g. a ModemStream, an MFSKStream or a Serial): the written data is sent in packets with CRC-16 and Reed-Solomon forward error correction, and only correct data can be read. Corrupted packets which can't be corrected are dropped
CPSKConfig	Configuration of the PSK modem (PSKEncoder, PSKDecoder): differential PSK with cosine shaped transitions like PSK31, compatible with fldigi
CVaricode	The PSK31 Varicode (as extended by fldigi to all 256 byte values): frequent characters have short codes. A code starts and ends with 1 and contains no "00": the characters are separated by "00"
CCode	Varicode bits of a character
CMFSKVaricode	The IZ8BLY MFSK Varicode (as used by fldigi for 8PSK): a code starts with 1 and does not contain "001", so a character ends when "001" is received (the 1 starts the next character)
CQPSKCode	Rate 1/2 convolutional code with K=5 (polynomials 0x17 and 0x19) of QPSK31 (fldigi) and a soft decision Viterbi decoder
CPSKDecoder	PSK demodulator (BPSK, QPSK and 8PSK compatible with fldigi): the PCM audio data is written to the decoder and the decoded bytes are written to the output. The input can be 8, 16 or 32 bit signed samples with any number of channels (only PSKConfig::channel is evaluated)
CPSKEncoder	PSK modulator (compatible with fldigi): the written bytes are Varicode encoded and each symbol is a phase step with a cosine shaped transition from the previous phase
CRSCodec	Reed-Solomon code over GF(256) with the polynomial 0x11d and lengths which are defined at runtime. The generator roots are alpha^fcr to alpha^(fcr+ecc-1): fcr = 0 is used by ggwave (Mike Lubinets' library) and IL2P, fcr = 1 by FX.25. The parity bytes follow the message, the first byte is the highest power (like Phil Karn's library)
CTables