Half Rate

Half Rate (HR or GSM-HR or GSM 06.20) is a speech coding system for GSM, developed in the early 1990s.

Since the codec, operating at 6.5 kbit/s, requires half the bandwidth of the Full Rate codec, network capacity for voice traffic is doubled, at the expense of audio quality. It is recommended to use this codec when the battery is low as it may consume up to 30% less energy. 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 algorithm. Previous specification was in ETSI ETS 300 581-2, which first edition was published in December 1995.

For some Nokia phones you can configure the use of this codec:

See also

Rate

Rate may refer to:

Science and finance

Human growth

Other uses

Ratež

Ratež (pronounced [ˈɾaːtɛʃ]) is a settlement in the hills east of Novo Mesto in southeastern Slovenia. The area is part of the traditional region of Lower Carniola and is now included in the Southeast Slovenia Statistical Region.

References

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Rate (mathematics)

In mathematics, a rate is the ratio between two related quantities Often it is a rate of change. If the unit or quantity in respect of which something is changing is not specified, usually the rate is per unit of time. However, a rate of change can be specified per unit of time, or per unit of length or mass or another quantity. The most common type of rate is "per unit of time", such as speed, heart rate and flux. Ratios that have a non-time denominator include exchange rates, literacy rates and electric field (in volts/meter).

In describing the units of a rate, the word "per" is used to separate the units of the two measurements used to calculate the rate (for example a heart rate is expressed "beats per minute"). A rate defined using two numbers of the same units (such as tax rates) or counts (such as literacy rate) will result in a dimensionless quantity, which can be expressed as a percentage (for example, the global literacy rate in 1998 was 80%) or fraction or as a multiple.