Quick and Practical reference list of Acronyms used in Timing applications
1PPS One Pulse Per Second time signal. Marks the beginning of standard second (TU-T G.703 and G.8271)
2Way TE PTP Time Transfer Error (packet-based)
APTS (GNSS) Assisted Partial Timing Support (ITU-T G.8275.2)
BDS BeiDou (Big Dipper) Navigation Satellite System, Chinese GNSS
BC Boundary Clock
BMCA Best Master Clock (selection) Algorithm
C/No Carrier-to-Noise density in dB-Hz (e.g., satellite signal quality)
Cs Cesium (used in atomic oscillators)
CSAC Chip-Scale Atomic Clock
cTE Constant (Mean or Average) Time Error
DOCXO Double-oven OCXO
DNU Do Not Use
dTE Dynamic Time Error
E2E End-to-End Path Delay Calculation Method
EEC (Synchronous) Ethernet Equipment Clock
ePRTC Enhanced Primary Reference Time Clock (ITU‐T G.8272.1)
ESMC Ethernet Synchronization Messaging Channel (ITU-T G.8264)
eSyncE Enhanced Synchronous Ethernet
FTS Full Time Support (ITU-T G.8275.1)
FPC Floor packet Count
FPP Floor Packet Percentile (FPP Limits are defined in ITU-T G.8261.1 as 1% of packets within 150 µsec of floor delay in every 200 sec period)
FPR Floor Packet Rate
Galileo European GNSS
GLONASS Globalnaya Navigatsionnaya Sputnikovaya Sistema, Russian GNSS
GM Grandmaster clock
GNSS Global Navigation Satellite Systems (generic for GPS, GLONASS, Galileo, Beidou, etc.)
GNSSDO GNSS-Disciplined Oscillator
GPS Global Positioning Satellite system, USA GNSS
GPSDO GPS-Disciplined Oscillator
gPTP generalized Precision Time Protocol (IEEE 802.1AS)
IED Intelligent Electronic Device (Power Utilities)
IEEE Institute of Electrical and Electronics Engineers (Standards body)
IP Internet Protocol (Layer 3), IP address
IPG Inter-Packet Gap
ITU-T International Telecommunication Union, Telecommunication Standardization Sector
LOS Line of Sight (GNSS RF signals)
LPF Low-Pass Filter
Layer 2 Ethernet MAC sublayer (switches). Provides flow control and multiplexing for the transmission media.
Layer 3 IP Layer (routers). Provides routing capabilities across network boundaries.
MAC Media Access Control, MAC Address (Ethernet)
MAC Miniature Atomic Clock
Max|TE| Maximum time difference between DUT and the reference
MTIE Maximum Time Interval Error
NE Network Element
NTP Network Time Protocol
OC Ordinary Clock (Master/source or Slave/destination device with single network connection)
OCXO Oven-Controlled Crystal Oscillator
Offset Error, deviation from the ideal frequency or time
OWD One-Way Delay (end-to-end latency)
P2P Peer-to-Peer Delay Calculation Method
PDV Packet Delay Variation (ITU-T G.8260 Appendix I defines a number of metrics that may be used for PDV analysis)
PEC Packet-based Equipment Clock
Phase Relative time difference between two 1PPS signals
PNT Positioning, Navigation and Timing applications
ppb Parts per Billion (1.00E-9), frequency error or uncertainty (offset)
ppm Parts per Million (1.00E-6), frequency error or uncertainty (offset)
ppt Parts per trillion (1.00E-12), frequency error or uncertainty (offset)
PRC Primary (frequency) Reference Clock (ITU‐T G.811)
Profile Set of definitions, settings and functionalities that fit an application.
PRS Primary Reference Source (see PRC)
PRTC Primary Reference Time Clock (ITU-T G.8272)
PSN Packet Switched Network
PTP Precision Time Protocol (IEEE 1588 2008/2019, ITU-T G.8275.1, G.8275.2)
PTS Partial Timing Support
QL (clock) Quality Level (ITU‐T G.781, for PTP Clock Class refer to G.8265.1 and G.8275.1)
Rb87 Rubidium (used in atomic oscillators)
RTD Round-Trip Delay
SC Slave Clock
SSM Synchronization Status Message (ITU-T G.707)
SSU Synchronization Supply Unit (TDM)
SVN Satellite Vehicle Number
SyncE Synchronous Ethernet (ITU-T G.8261, G.8262, G.8264)
T1 GM departure timestamp for outgoing Sync messages (one-step: carried in the Sync message itself, or two-step: carried in the Follow_Up message)
t2 Measured arrival timestamp for the Sync message, at the T-SC
t3 Measured timestamp of Delay_Request message departure from T-SC
T4 GM arrival timestamp for incoming Delay_Request messages, sent inside the Delay_Response message
TAI Atomic Time (Temps Atomique International), PTP time
T-BC Telecom Boundary Clock (PTP aware switch) ITU-T G.8273.2
T-BC-A Telecom Boundary Clock for Assisted partial timing support
T-BC-P Telecom Boundary Clock for Partial timing support
TC Transparent Clock (PTP aware switch)
TCXO Temperature-Compensated Crystal Oscillator
TDEV Time Deviation
TDM Time Division Multiplexing (networks) such as SDH/SONET, PDH/DSn
TE Time Error, relative to a standard time reference. (TE = cTE + dTE)
TE1 Forward (Sync) Time Error
TE4 Reverse (Delay_Request) Time Error
T-GM Telecom Grandmaster Clock (precision time server)
TIE Time Interval Error
TLV Type, Length, Value (message fields)
ToD Time of Day label identifying the last 1PPS pulse (YYYY-MM-DD hh:mm:ss)
T-SC Telecom Slave Clock (client)
TSN Time-Sensitive Network/Networking
T-TSC Telecom Time Slave Clock (time-oriented client)
T-TC-P Telecom Transparent Clock for Partial timing support
T-TSC-A Telecom Time Slave Clock for Assisted partial timing support
T-TSC-P Telecom Time Slave Clock for Partial timing support
UDP User Datagram Protocol (Layer 4)
UTC Coordinated Universal Time
VCXO Voltage-Controlled Crystal Oscillator
XO Xtal (crystal) Oscillator. (e.g., Quartz)