T
Tomi Holger Engdahl
- Jan 1, 1970
- 0
Bob Shuman said:
And agt some countries that 450 MHz frequency band has been used
for cellular phone systems for decades!
For example NMT (Nordic Mobile Telephone) network opened in Finland
at 1982. That network was international standard covering many
Northern European countries (at least Finland, Sweden and Norway).
Later that system was expaded to be used als on Russia and
many Eastern European countries.
In Finland 450 MHz band became popular and pretty heavuly loaded.
The new network based on same basic technology but perating at 900 MHz
was started at 1987.
This NMT system was an analogue system that is nowadays phased out,
not operating in Finland anymore.
The 900 Mhz frequency band is nowdays used by digital GSM cellular
phone system. The use of GSM system started at 1992 in Finland.
First it operated side by side at different channels at 900 Mhz
frequency band. Later when 900 MHz NMT system phased out,
the cellular phone band was entirely used by GSM system.
To get more capacity operators started around 1996-1997 to
implement GSM network tat operates at 1800 MHz frequency band
to ajor cities. The 1800 MHz network is generally used with
"dual band" phones that can use both 900 MHz and 1800 MHz bands.
The major operators in Finland have network operating at both
frequencies, and the phones seamlessly switch between
those networks automatically (user does not worry
about frequency band).
Most information on this posting is taken from my
course paper I made at 1996 in Helsinki University of Technology.
The paper is written in Finnish and available on-line at
http://users.tkk.fi/~then/matkapuhelin/index.html
