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White Paper T630/T628
23 October 2003
Polyphonic ring signals
Protocol
The T630/T628 has a hardware synthesizer chip,
built into the mobile phone. The software controls
the MIDI files, and makes sure they fit into the hard-
ware chip. It is possible to modify the dynamics,
and it is possible to make the sound escalate, start
quietly and grow louder.
The T630/T628 Sony Ericsson mobile phone com-
pletely supports the MIDI 1.0 detailed specification.
Please visit http://www.midi.org/ for more informa-
tion.
Excellent sound quality – 32voices
The human ear can hear sounds from approxi-
mately 20 Hz up to 20 KHz. In most GSM mobile
phones, the speech sound range is from 300 Hz to
3400 Hz, which is good enough for speaking, but
quite poor for music. The T630/T628 can handle up
to 15000 Hz, equivalent to an FM stereo radio,
which means excellent sound quality.
T630/T628 has a dedicated speaker to ensure the
best possible sound quality. This speaker is situ-
ated on the back of the phone ensuring no discom-
fort is felt if a second call is received during an
ongoing call. It also ensures louder ring signals and
removes the need for escalating rings signals.
The quality of the sound heard from the speakers
depends on many different things, for example on
the synthesizer, the amplifier, or the speakers. An
important factor for sound quality is the number of
voices. The human ear cannot separate each voice
if the number of voices increases above about 16,
then the voices merge together. But the nuances in
the music increase, and the music is experienced
as more sophisticated if the number of voices
increases. Many modern sound modules in synthe-
sizers used by musicians have 16, 24 or 32 note
polyphony. The number of voices used in the T630/
T628 is 32, which gives excellent sound quality.
Wavetable synthesis
Sony Ericsson has chosen to implement the
Wavetable synthesis, which consists of sampled
real instruments, which gives a much higher quality
than the FM-synthesis. Especially the treble is more
distinguished.
Touch correct feature
The so called “Touch correct” feature makes
dynamic compression possible. This equalizes the
amplitude of the instruments included in the MIDI
file, which greatly improves the sound quality,
especially in melodies with big differences in ampli-
tude.
Bluetooth™ wireless technology
The T630/T628 features built-in Bluetooth wireless
technology. Its short-range radio link operates in
the globally available 2.4 GHz radio frequency
band, ensuring fast and secure communications up
to a range of 10 metres.
Bluetooth wireless technology is designed to be
fully functional even in noisy radio frequency envi-
ronments. All data transfer is protected by
advanced error-correction methods, ensuring a
high level of data security. Bluetooth wireless tech-
nology facilitates instant connections, which are
maintained even when the devices are not within
line of sight. High-quality voice transmission is pro-
vided under adverse conditions, making it possible
to use a headset connection to the T630/T628 at all
times.
Ericsson was a founding partner of the Bluetooth
Special Interest Group (SIG). Bluetooth wireless
technology devices that are expected to be availa-
ble in the near future, include:
• Headsets for wireless voice transmission and
remote call control
• PCs, laptops, PDAs, palmpads for data transfer,
synchronization etc.