Rdi (Restricted Digital Information); Khz Audio; Ambe (Advanced Multi-Band Excitation); Dsp (Digital Signal Processor) - Furuno Felcom 250 Service Manual

Appendix 4. Abbreviations

RDI (Restricted Digital Information)

An ISDN terminology which refers to restricted digital information.
This equipment establishes communication via the serial port. The communication
speed is 56 kbps, and the modem installed in the PC is the standard modem 33600 bps.

3.1 kHz Audio

A type of ISDN service which provides the information forwarding capability within the
"3.1 kHz" to be used for transmitting voice band data or G3 fax signals using the
modem.
Interconnection can be established between the network for the user of an existing
telephone network and an ISDN user.
Therefore, the 64 kbps 3.1 kHz Audio service is provided for the purpose of realizing
the communication capabilities equivalent with the "deemed" capability for ISDN.

AMBE (Advanced Multi-Band Excitation)

An audio compression method developed by DVSI. It ensures the communication
quality by using a narrower transmission band than the other various linear predictive
coding methods, and is stronger for transmission errors or noises.

DSP (Digital Signal Processor)

A microprocessor specialized for processing digital signals.
It processes functions that had been difficult to be processed by traditional analog
processing methods by digitizing the signals at real-time, and it is enabled to process the
signals at a speed higher than general microprocessors by using a hardware such as the
sum-of-product logic circuit, etc.

C/No

The signal level and the noise ratio per 1 Hz.
For example, when C/N 50 dB is converted into C/No when the noise bandwidth is 4
kHz, the noise ratio can be calculated by; 50 dB + 10 log 4000 (dB/Hz).
Note that since "No" in C/No is the noise level per bandwidth 1Hz, its unit will be
dB/Hz.

RSSI (Received Signal Strength Indicator)

The circuit or signal used for measuring the strength of the signals received by the radio
communication equipment. This equipment measures RSSI using the Antenna unit.
AP4-4