Half Rate (HR or GSM-HR or GSM 06.20) is a
speech coding
Speech coding is an application of data compression to 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 da ...
system for
GSM
The Global System for Mobile Communications (GSM) is a family of standards to describe the protocols for second-generation (2G) digital cellular networks, as used by mobile devices such as mobile phones and Mobile broadband modem, mobile broadba ...
, developed in the early 1990s.
Since the
codec
A codec is a computer hardware or software component 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 o ...
, 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 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
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of Information and communications technology, information and communications. ETSI supports the de ...
EN 300 969 (GSM 06.20), and uses a form of the
VSELP algorithm. Previous specification was in
ETSI
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of Information and communications technology, information and communications. ETSI supports the de ...
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
* Enhanced Full Rate (EFR)
* Adaptive Multi-Rate (AMR)
* Adaptive Multi-Rate Wideband (AMR-WB)
* Extended Adaptive Multi-Rate - Wideband (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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