A/D conversion (analogue-to-digital conversion) | The process of converting a time-continuous analogue signal to a sampled digital representation |
Additive White Gaussian Noise (AWGN) | The term describing a noise signal which has a flat power spectral density with frequency |
Amplitude Shift Keying (ASK) | A digital modulation format where information is conveyed in the amplitude of a carrier signal |
Automatic Repeat Request (ARQ) | Protocol for dealing with data words that are corrupted by errors whereby the receiving system requests a re-transmission of the word(s) in error |
BCH | A type of block coding of data words named after the inventors Bose, Chaudhuri and Hocquenghem |
Binary Phase Shift Keying (BPSK) | Digital modulation format where information is conveyed in the phase of a carrier signal: usually 0o and 180o |
Bit error rate (BER) | A measure of the number of bit errors occurring in a transmitted data sequence |
Code Division Multiple Access (CDMA) | Method of combining multiple users on a given channel bandwidth using unique spreading codes, or hopping patterns to distinguish any given user |
Continuous Phase Frequency Shift Keying (CPFSK) | Digital modulation format where information is conveyed in the frequency of a carrier signal ensuring that the phase is continuous between symbol transitions |
D/A conversion (digital-to-analogue conversion) | The process of converting a discrete time digital representation of a waveform to a continuous analogue voltage equivalent |
dBc | The level of a signal in dB relative to a wanted carrier signal level |
dBm | the level of a signal in dB relative to 1mW (0dBm) |
Differential Phase Shift Keying (DPSK) | Digital modulation format where information is conveyed in the phase difference of a carrier signal between consecutive symbols |
Differentially Encoded Phase Shift Keying (DEPSK) | Digital modulation format where data is pre-coded to convey information in the change of state between consecutive bits, to overcome the phase ambiguity problem with coherent phase shift keying |
Digital Audio Broadcasting (DAB) | The generic name given to the new generation of radio transmission using digitally encoded audio waveforms |
Digital Video Broadcasting (DVB) | The generic name for the new generation of image and sound transmission using a digitised version of the image signal |
Dynamic Channel Multi-carrier Architecture (DC/MA) | A proprietary radio system designed by Wireless Systems International for ComSpace Corporation |
Eb | Symbol denoting the energy required to represent 1 bit of information in the modulated signal |
Es | Symbol denoting the energy required to represent 1 symbol of information in the modulated signal |
European Telecommunications Standards Institute (ETSI) | The body in Europe responsible for setting standards relating to wireless communications |
Feed Forward Signal Regeneration (FFSR) | A method for correcting for multipath fading and frequency error in mobile radio systems using a pilot reference tone |
Forward Error Correction (FEC) | An error correction method allowing detection and correction of bit or word errors without the need to re-transmit the data |
Frequency Division Multiple Access (FDMA) | Method of combining multiple users on a given channel bandwidth using unique frequency segments |
Frequency Shift Keying (FSK) | Digital modulation format where information is conveyed in the frequency of a carrier signal |
Gaussian Minimum Shift Keying (GMSK) | Digital modulation format where information is conveyed in the frequency of a carrier signal, where the incoming data is first shaped with a Gaussian low-pass filter |
GSM (Global System for Mobile communications) | A cellular radio standard using digital GMSK modulation |
Intermediate Frequency (IF) | A special frequency used in radio systems as part of the up-conversion or down-conversion process; usually where the channel selection is made |
Intersymbol interference (ISI) | Interference between adjacent symbols often caused by system filtering, dispersion in optical fibres, or multipath propagation in radio system |
International Telecommunications Union (ITU) | The body overseeing standards and regulation for the wired communications industry |
M-ary Amplitude and Phase Keying (M-ary APK) | Digital modulation format where information is conveyed in the amplitude and phase of a carrier signal |
M-ary Amplitude Shift Keying (M-ASK) | Digital modulation format where information is conveyed in the 'M' amplitudes of a carrier signal |
M-ary Phase Shift Keying (M-PSK) | Digital modulation format where information is conveyed in the 'M' phases of a carrier signal |
M-ary Quadrature Amplitude Modulation (M-QAM) | Digital modulation format where information is conveyed in the 'M' amplitude and phase combinations of a carrier signal |
Minimum Shift Keying (MSK) | Digital modulation format where information is conveyed in the frequency of a carrier signal with modulation index equal to half the symbol period |
N0 | The noise power density measured in Watts/Hz |
Non Return to Zero (NRZ) | Binary data encoding format |
ON-OFF Keying (OOK) | Digital modulation format where information is conveyed by switching on and off a carrier signal |
Orthogonal Frequency Division Multiplexing (OFDM) | Modulation format where information is sent over multiple parallel adjacent frequency channels where the carrier frequencies are orthogonal |
Pb | Probability of receiving a data bit in error |
PCS (Personal Communications System) | Common term for cellular radio predominantly in North America |
Phase Locked Loop (PLL) | Feedback control circuit for tracking the frequency and phase of an incoming signal, often used in modem carrier recovery circuits |
Ps | Probability of receiving a data symbol in error |
Quadrature Amplitude Modulation (QAM) | Digital modulation format where information is conveyed in the amplitude and phase of a carrier signal |
Quadrature Phase Shift Keying (QPSK) | Digital modulation format where information is conveyed in four equi-spaced phases of a carrier signal |
RF | Radio Frequency |
rms | root mean square |
RS (ReedSoloman) | A type of block code for error detection and correction |
RX | Short for receiver |
S/N ratio | Signal-to-noise ratio |
Symbol Error Eate (SER) | The probability of receiving a symbol in error (not to be confused with Bit Error Rate) |
Tb | The period of 1 data bit |
TETRA (Trans European Trunked Radio) | The name of the ETSI-standardised radio system for private and public mobile two-way radio applications |
Time Division Multiple Access (TDMA) | Method of combining multiple users on a given channel bandwidth using unique time segments |
Trellis Coded Modulation (TCM) | Method of coding multiple symbols to give improved symbol error rate performance in noisy conditions |
TX | Short for transmitter |
Voltage Controlled Crystal Oscillator (VCXO) | A circuit whose oscillating frequency is tied to that of a crystal (fundamental or harmonic) |
Voltage Controlled Oscillator (VCO) | A circuit whose output frequency varies in sympathy with an input voltage |
Wavelength Division Multiplexing (WDM) | Method of combining multiple users on a given channel bandwidth using unique wavelengths (or frequencies as in FDMA) |