Half Rate (HR or GSM-HR or GSM 06.20) is a
speech coding
Speech coding is an application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic d ...
system for
GSM
The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...
, developed in the early 1990s.
Since the
codec
A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder.
In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...
, operating at 5.6 kbit/s, requires half the
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
of the
Full Rate
Full Rate (FR or GSM-FR or GSM 06.10 or sometimes simply GSM) was the first digital speech coding standard used in the GSM digital mobile phone system. It uses linear predictive coding (LPC). The bit rate of the codec is 13 kbit/s, or 1.625 bits ...
codec, network capacity for voice traffic is doubled, at the expense of audio quality. The sampling rate is 8 kHz with resolution 13 bit, frame length 160 samples (20 ms) and subframe length 40 samples (5 ms).
GSM Half Rate is specified in
ETSI EN 300 969 (GSM 06.20), and uses a form of the
VSELP
Vector sum excited linear prediction (VSELP) is a speech coding method used in several cellular standards. The VSELP algorithm is an analysis-by-synthesis coding technique and belongs to the class of speech coding algorithms known as CELP (Code Exc ...
algorithm. Previous specification was in
ETSI ETS 300 581–2, which first edition was published in December 1995.
ETSI ETS 300 581-2 - Half rate speech transcoding (GSM 06.20 version 4.3.1)
Retrieved on 2009-07-11
For some Nokia phones one can configure the use of this codec:
* To activate HR codec use enter the following code: *4720#
* To deactivate HR codec use enter the following code: #4720#
See also
* Full Rate
Full Rate (FR or GSM-FR or GSM 06.10 or sometimes simply GSM) was the first digital speech coding standard used in the GSM digital mobile phone system. It uses linear predictive coding (LPC). The bit rate of the codec is 13 kbit/s, or 1.625 bits ...
* Enhanced Full Rate (EFR)
* Adaptive Multi-Rate
The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at var ...
(AMR)
* Adaptive Multi-Rate Wideband
Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech audio coding standard developed based on Adaptive Multi-Rate encoding, using a similar methodology to algebraic code-excited linear prediction (ACELP). AMR-WB provides improved sp ...
(AMR-WB)
* Extended Adaptive Multi-Rate - Wideband
Extension, extend or extended may refer to:
Mathematics
Logic or set theory
* Axiom of extensionality
* Extensible cardinal
* Extension (model theory)
* Extension (predicate logic), the set of tuples of values that satisfy the predicate
* Ext ...
(AMR-WB+)
References
External links
ETSI EN 300 969 - Half rate speech transcoding (GSM 06.20 version 8.0.1 Release 1999)
- technical specification
ETSI ETS 300 581-2 - Half rate speech transcoding (GSM 06.20 version 4.3.1)
- obsoleted
- technical specification
* - RTP Payload format for GSM-HR
Audio codecs
Speech codecs
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