|
|
|
|
|
Bits and Bytes: how fast are 3G wireless devices?
How long does it takes to download a full screen picture or a file to a 3G phone?
To fill a 128 x 160 pixel screen with 24-bit colour image:
Image width x height x colour bytes per pixel x 8 (bits per byte)
128 x 160 x 3 x 8 = 491 520 bits without any image compression
Depending on the file format:
image about 5 kbytes = 40 000 bits
image about 15 kbytes = 120 000 bits
image about 30 kbytes = 240 000 bits
If you have a 384 kbit/s 3G downlink channel, downloading takes less than a second.
4 Mbyte audio file download would take approximately 90 second.
Note: 384 kbit/s is a peak downlink speed. Average speeds depends on retransmission factors, interference conditions etc. Normal average download speed might be 70% - 80 % of the peak speed.
Definitions:
Bit, The fundamental unit of computer storage. [more]
"Computers store data using tiny electronic devices called gates, which are either open (electricity flows through) or closed (no electricity flows through). These two states are represented using the binary number system, where 1 means open and 0 means closed. These are the bits -- a blend of binary and digits."
Wireless transmission speed is usually measured in bits per second.
Byte, 8 bits. A single character of information. [more]
File sizes, memory capacity, and hard disk capacity are all usually measured in hundreds, thousands, or millions of bytes. Here's a review of the prefixes used at various levels of "bigness":
PREFIX POWER UNITS NUMBER
of 10
kilo- 3 thousands 1,000
mega- 6 millions 1,000,000
giga- 9 billions 1,000,000,000
tera- 12 trillions 1,000,000,000,000
peta- 15 quadrillions 1,000,000,000,000,000
exa- 18 quintillions 1,000,000,000,000,000,000
zetta- 21 sextillions 1,000,000,000,000,000,000,000
yotta- 24 septillions 1,000,000,000,000,000,000,000,000
Pixel, The smallest resolvable rectangular area of an image, either on a screen or stored in memory. In a colour image, each pixel has its own brightness and colour, usually represented as a triple of red, green and blue intensities. Full photographic colour resolution must account for millions of individual colours. While this is possible on any modern colour monitors, for economic (memory) reasons many systems are limited to display a much smaller range.
Typical 3G phone display colours:
4096 colours, Nokia GSM 3650, 7650, Ericsson P800
32,768 colours
65,536 colours, Nokia GSM 6600
262,144 colours, Sanyo V-SA701, Samsung SPH-V3000
Typical 3G phone display sizes (w x h):
96 x 64 pixels = 6144 pixels
128 x 160 pixels = 20480 pixels, Nokia 6650 (video 128 x 96 pixel)
176 x 192 pixels = 33792 pixels, Samsung SPH-V3000
176 x 208 pixels = 36608 pixels, Nokia 6600, 3650, 7650
176 x 220 pixels = 38720 pixels, Motorola A830, SonyEricsson Z1010, Sanyo V-SA701
208 x 320 pixels = 66560 pixels, Sony Ericsson GSM Phone P800
Symbian UIQ screen is 208 – 240 x 320 pixels pixels; Dot pitch: 0.19 – 0.24 [more]
Nokia 60 series display is 176 pixels wide, Like Nokia 3650 (176 x 208 pixels)
3G / UMTS data speed:
64 kbits per second
384 kbits per second
2 Mbits per second
~10 Mbits per second (future UMTS HSPDA)
Typical file size examples (bytes):
2 kbytes, one page of text
50 kbytes, typical Internet web page
20 kbytes, an Internet image
1 Mbyte, a digital camera picture
4 Mbytes, a mp3 audio file
|
|
