Developer glossary

Protocol, hardware and firmware terms of the specs and developer docs. Terms the user guide uses are in the glossary.

DMR

Term	Meaning
AIS	Air interface specification, the ETSI name for DMR's over-the-air rules.
ALS	Ambient listening service: a dispatcher turns on a radio's microphone remotely.
AT	Access type: the TACT bit that tells a radio whether the slot is free to transmit in.
BER	Bit error rate: the share of received bits that were wrong. A measure of how clean a signal is.
BPTC	Block product turbo code: the error correction on DMR headers and control blocks.
BS	Base station: the repeater or modem side of a DMR link, as opposed to the radio (MS).
BS_Dwn_Act	The CSBK that tells a repeater to start transmitting. It wakes a repeater.
Burst	One DMR transmission in a slot: 264 bits, with a sync pattern or embedded signaling in the middle.
C_ACKD (C_NACKD, C_WACKD, C_QACKD)	A Tier III CSBK in which the TSCC accepts a request.
C_ACKU (P_ACKU)	A Tier III CSBK in which a radio acknowledges or answers, for example the authentication response.
C_AHOY	A Tier III CSBK that checks on a radio: an authentication challenge or the called party's radio check.
C_ALOHA	The Tier III CSBK a trunked base station sends to announce the system and its slot timing.
C_RAND	The Tier III CSBK a radio sends to ask for something on the control channel: registration, a call.
C_SYS_Parms	The Tier III system parameters a TSCC sends in its CACH (SLCO 0010): model, network, site, registration flag and slot counter.
C_SYScode	The 16-bit system code of a Tier III system: MODEL, NET, SITE and PAR. C_ALOHA carries all of it, the CACH the top 14 bits.
CACH	Common announcement channel: 24 bits ahead of each burst a repeater sends. It carries the slot number and short link control.
Codec	A voice codec. DMR uses AMBE+2.
CSBK (CSBKs)	Control signaling block: a one-burst DMR message for signaling such as call alert, radio check and Tier III control. More
CSBKO	CSBK opcode: the field of a CSBK that says its kind.
DD (DD format)	Defined data format: the field of a short data header that says how its payload is coded (7-bit text, ISO 8859, UTF-16 and so on).
DGNA	Dynamic group number assignment: the Tier III system moves a radio into a talkgroup over the air.
Direct mode (DMO)	DMR radio to radio on one frequency, with no repeater. The standard calls it DMO.
DMRLA	DMR location area: how many of the most significant bits of SITE form SYS_AREA, the registration area.
DPF	Data packet format: the field of a data header that says what follows (unconfirmed or confirmed data, UDT, short data).
DT	Data type: the field of a burst's slot type that says what the burst carries (header, terminator, rate 1/2 block and so on).
EMB	Embedded signaling: the 32 bits in the middle of a voice burst that carry link control.
ETSI	European Telecommunications Standards Institute, which publishes the DMR standard.
FEC	Forward error correction: extra bits that let the receiver repair errors without a resend.
FID	Feature set ID: the byte that says whether a message is standard or manufacturer specific.
FLCO	Full link control opcode: the field of a link control message that says its kind.
FOACSU	Full off air call set up: OACSU with alerting, so the called radio rings and answers before voice.
FSN	Fragment sequence number: counts the fragments of a data packet that was split.
LB	Last block: the flag that marks the final block of a CSBK or data message.
LC (embedded LC)	Link control: the call's addressing (source, destination, group or private) that DMR repeats through a voice call.
LCSS	Link control start/stop: the 2-bit field of a burst's embedded signaling that says which fragment it carries.
LLID	Logical link ID: the 24-bit address (a DMR ID or a talkgroup number) in a data header.
LPCN	Logical physical channel number: the number of a channel in a Tier III channel plan.
MBC	Multi block control: a DMR signaling message that spans several bursts.
MI	Message indicator: the value that changes with each call and keys its encryption. It travels in the PI header.
MPT 1327 (MPT)	The analog trunking standard that Tier III descends from.
MS	Mobile station: the radio, as opposed to the base station (BS).
OACSU	Off air call set up: signaling that sets up a call before voice is sent. The radio asks over the air and waits for the answer.
P_SYS_Parms	The same system parameters a Tier III payload channel sends in its CACH (SLCO 0011).
PABX	Private automatic branch exchange: an office telephone system. Tier III can connect calls to it.
PDU (PDUs)	Protocol data unit: one packet or message of a protocol, as the standard defines its fields.
PF	Protect flag: the bit in link control that marks a protected (encrypted) call.
PSN	A 3-octet number XORed into the Tier III authentication response when a network uses it.
PSTN	Public switched telephone network. Tier III can connect calls to it.
PV_GRANT (TV_GRANT, BTV_GRANT)	A Tier III grant: the TSCC tells radios which payload channel carries a call. PV is a private voice call, TV a talkgroup voice call, BTV a broadcast talkgroup voice call.
RC	Reverse channel: signaling the receiver sends back to the transmitter during a call, in space the burst leaves free.
Repeater mode (RMO)	DMR through a repeater, which receives on one frequency and transmits on another. The standard calls it RMO.
SAID (DAID)	Source address ID: the field of a compressed UDP/IP header that says where the source IP address comes from, for example from the LLID.
SAP	Service access point: the field in a DMR data header that says what the payload is (IP, short data, GPS and so on).
SLCO	Short link control opcode: the field of a short LC message that says its kind.
SPID (DPID)	Source port ID: the index in a compressed UDP/IP header that stands for a well-known UDP port.
Sync	The 48-bit pattern in the middle of a burst. It tells the receiver the burst's kind (voice or data, base station or radio) and its timing.
TACT	The 7 bits at the start of a CACH: AT, TC, LCSS and Hamming parity.
TC	TDMA channel: the TACT bit that names the timeslot, so a radio can tell TS1 from TS2.
TDMA	Time division multiple access. A DMR channel carries two conversations by alternating them in 30 ms slots.
Tier II	The conventional DMR tier of the standard (TS 102 361-2): repeaters and direct mode without trunking.
Tier III	The trunked DMR tier of the standard (TS 102 361-4): a control channel assigns traffic channels. More
TSC	The controller of a Tier III system: the infrastructure side the radio talks to.
TSCC	Trunked station control channel: the Tier III channel that carries control signaling.
TSCCAS	TSCC alternate slot: a second control slot of a Tier III site.
UDT	Unified data transport: DMR short data sent as a plain block of bytes.

RF and hardware

Term	Meaning
ADC	Analog to digital converter.
AFC	Automatic frequency control: following a transmitter that is slightly off frequency.
AGC	Automatic gain control: the receiver adjusting itself to the signal level.
AT1846S	The RF transceiver chip that sets the frequency, deviation and power of many handheld DMR radios. Programmed over I2C.
CPU	Central processing unit.
CRC	Cyclic redundancy check: a checksum that detects damaged data.
DAC	Digital to analog converter.
Deviation	How far an FM transmitter's frequency swings from the channel center. It sets loudness and bandwidth.
DMA	Direct memory access: moving data between memory and a peripheral without the processor.
DSP	Digital signal processor: a chip, or a processor core, that does the audio and modem math.
ECC	Error correcting code: a code that repairs damaged bits, such as the one a NAND flash needs.
EEPROM	Electrically erasable programmable read-only memory: a small chip that keeps settings.
FIFO	First in, first out: a queue of data between a producer and a consumer.
FSK	Frequency shift keying: data as frequency steps. DMR uses 4-level FSK.
GPIO	General purpose input/output: a pin the firmware can read or drive.
HR_C6000 (HRC6000, C6000)	The HRC6000 family: the baseband chip that codes and decodes DMR bursts. The radios that use it are in the radio survey.
HR_C7000 (HRC7000, C7000)	The HRC7000 family: the baseband chip of the C-SKY class radios. The radios that use it are in the radio survey.
I2C (I²C)	Inter-integrated circuit: a 2-wire bus for small chips such as the RF transceiver.
I2S	Inter-IC sound: the bus audio samples travel on between chips.
JTAG	A debug and test port of many processors.
MCU	Microcontroller: the processor that runs the firmware.
NAND	The flash chip type that holds large data, such as the codeplug and contacts, in some radios.
NOR	The flash chip type that holds code and can run it in place.
OTG (OTG_FS)	USB On-The-Go: the controller can act as the host or the device.
PA	Power amplifier: the stage that boosts the transmit signal to the output power.
PCM	Pulse code modulation: audio as a stream of sample numbers.
PLL	Phase locked loop: the circuit that holds the radio's synthesizer on its frequency.
ppm	Parts per million: a frequency error as a fraction of the frequency. At 450 MHz, 1 ppm is 450 Hz.
PWM	Pulse width modulation: a pin switched on and off to give an average level, as for backlight or tone.
RAM	Random access memory: working memory that loses its content at power off.
ROM	Read-only memory: code fixed in the chip.
SNR	Signal to noise ratio.
SPI	Serial peripheral interface: the 4-wire bus the processor uses to talk to chips such as the modem.
SRAM	Static RAM: the processor's fast working memory.
STM32 (STM32F4, STM32F405)	STMicroelectronics' family of ARM microcontrollers. The radios that use it are in the radio survey.
SWD	Serial wire debug: the two-wire debug port of ARM processors.
Synthesizer	The part that makes the radio's transmit and receive frequencies.
TCXO	Temperature compensated crystal oscillator: the stable clock the radio's frequency is derived from.
UART	Universal asynchronous receiver transmitter: a serial port.
VCO	Voltage controlled oscillator: the oscillator in a synthesizer, tuned by a voltage.

Vendor terms

Term	Meaning
CAI	Common air interface: Motorola's name for the DMR air interface, also the name of its IP addressing on the air.
Capacity Plus (Cap+)	A MOTOTRBO single-site trunking mode in which the radios share a pool of repeater channels.
Connect Plus	A MOTOTRBO multi-site trunking system with a central controller.
DCDM	Dual Capacity Direct Mode: Motorola's direct mode that carries two calls on one frequency, one per timeslot.
ERDM	Motorola's style of single frequency repeater, with different inbound and outbound color codes.
IPSC	IP Site Connect: Motorola's linking of repeaters over IP.
Linked Capacity Plus (LCP)	A MOTOTRBO system of several Capacity Plus sites joined by a network.
XNL (XCMP)	A Motorola radio control protocol; XCMP commands travel over it. Neither is part of the standard.

Amateur and network

Term	Meaning
ACK (NAK)	Acknowledgment: the reply that says a message arrived.
AFSK	Audio frequency shift keying: data as two audio tones on an FM carrier. APRS at 1200 baud uses it.
DHCP	Dynamic Host Configuration Protocol: how a device gets its IP address on a network.
IP	Internet Protocol: the addressing and packet layer of networks.
NCM (CDC-NCM)	Network control model: the USB class that makes the radio appear as a network adapter.
PPP	Point-to-point protocol: IP over a serial link. More
TCP	Transmission Control Protocol: IP connections with ordered, guaranteed delivery.
TNC	Terminal node controller: the modem that turns packet data into audio tones and back.
UDP	User Datagram Protocol: IP packets with no delivery guarantee.

RadioFoundry and firmware

Term	Meaning
ASCII	The 7-bit character set of plain text.
BCD	Binary coded decimal: each decimal digit in 4 bits.
Board	The code and description of one radio model's hardware wiring: pins, chips, memory map. More
CI	Continuous integration: the checks every change must pass (tools/ci.sh).
Debug link	RadioFoundry's USB serial protocol for reading state and driving the radio from a computer. More
Feature switch	A CONFIG_ option that turns a feature's code in or out of the build. More
GPL	GNU General Public License. RadioFoundry does not use GPL code.
HAL	Hardware abstraction layer: the interfaces the core uses instead of touching a chip. More
HIL	Hardware in the loop: tests that run against a real radio, and a bench radio or SDR for the other side. More
KB (MB)	Kilobytes (1024 bytes).
LTO	Link-time optimization: the compiler optimizes across files. It shrinks the firmware.
MIT	The permissive license RadioFoundry uses.
MSB (LSB)	Most significant bit (or byte): the first, highest-value one.
OS	Operating system.
RTOS	Real-time operating system: the scheduler that runs the firmware's tasks.
SD	Secure Digital: removable memory card.
SDR	Software defined radio: a receiver that digitizes the radio spectrum so software can decode it. The SDR bench uses one.
SIL	Software in the loop: tests that run the firmware's core on the host with a simulated radio.
SoC	System on chip: the processor and its on-chip peripherals.
ST	STMicroelectronics, the maker of the STM32 processors.
Stub	A small program that runs on the radio in place of the firmware so the computer can read or write flash without the stock bootloader.
USRP	The UDP stream that carries a call's audio between RadioFoundry and a network gateway.
XIP	Execute in place: running code straight from flash.
XOR	Exclusive or: a bit operation that flips bits where the other operand has a 1.

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