Specifications

Bluegiga Technologies Oy
Page 14 of 64
THD+N 16Ω Load
-
-
0.1
%
THD+N 100Ω Load
-
-
0.01
%
Table 8: DAC Characteristics
4.4.3 A2DP Codecs
4.4.3.1 SBC
SBC codec is the default codec used for Bluetooth A2DP connections. Any Bluetooth device supporting A2DP
audio profile supports SBC codec. SBC was originally design to provide reasonable good audio quality while
keeping low computational complexity. SBC does not require high bit rates. Thus it works sufficiently with
Bluetooth where the bandwidth and the processing power are limited.
4.4.3.2 aptX®
The aptX is widely used in high quality audio devices. aptX can provide dynamic range up to 120 dB and it
has the shortest coding delay (<2ms) than other coding algorithms. Using aptX
®
the whole system latency can
be reduced significantly because unlike SBC, it does not require buffering the audio. SBC reproduces a limited
audio band width whereas aptX
®
encode the entire frequency range of audio.
aptX
®
is more robust and resilient coding scheme than SBC and thus re-transmits does not occur as with
SBC.
Both SBC and aptX
®
have flat frequency response up to 14 kHz. Up to 14 kHz both algorithms produce good
quality audio with very little distortion. At frequencies higher than 14 kHz the benefit of aptX
®
becomes
obvious. SBC exhibits increasing attenuation with increasing frequency but aptX
®
retains high reproduction
quality.
aptX
®
requires purchasing a license for each Bluetooth address and the license agreement must be done with
CSR. The combination of aptX
®
license and the Bluetooth address is programmed into the module in the
module production line.
Figure 3: Frequency response of aptX and SBC codecs