RF OVERVIEW
MCUK991001G8
Section 3
Issue 1
Technical Guide
– 9 –
Revision 0
3 RF OVERVIEW
3.1 Introduction
3.1.1 General Specifications
GD30/GD50 is a Dual Band product incorporating two switchable transceivers, one for the GSM900 band and another for the
GSM1800 (DCS1800) band. The transmit and receive bands for the mobile are given in the table below:
Other salient technical features are as follows:
3.1.2 Description of Main PCB
All components required for the RF and Logic circuits, excluding the LCD module and backlight LEDs, are contained on the
Main PCB. The Main PCB has six layers made from FR4 material (Epoxide woven glass fabric copper-clad laminate as
specified in BS4584 Part 102 and prepeg as specified in BS4584 Part 103). Top and bottom layer tracks are gold-plated to
prevent oxidisation and enable better soldering. The board thickness is 0.9 mm (± 0.1 mm).
The majority of RF components are located on the side of the Main PCB that faces the chassis, allowing some groundplane
on the opposite side for RF shielding. The Main board is connected to the Keypad PCB via a 34-way dual in-line connector. A
metallised plastic chassis is used to separate the Main and the Keypad PCBs. When the chassis is sandwiched between the
Main and the Keypad PCBs, the groundplane of the Main board together with the chassis forms an effective shielded enclosure
which prevents spurious emissions. The chassis has also been designed to provide smaller walled sections which are used to
isolate sensitive RF areas such as the VCTCXO and the VCO from high level interference sources such as the PA output.
3.2 Functional Description
3.2.1 Frequency Plan
The GD30/GD50 frequency plan is shown below
.
Tx
Rx
GSM900
890-915 MHz
935-960 MHz
GSM1800
1710-1785 MHz
1805-1880 MHz
GSM900
GSM1800
Units
Rx Bandwidth
25
75
MHz
Tx Bandwidth
25
75
MHz
Duplex Spacing
45
95
MHz
Number of Channels
124
374
ARFCN (Channel Numbers)
1-124
512-885
1st Tx Channel
890.2
1710.2
MHz
Last Tx Channel
914.8
1784.8
MHz
1st Rx Channel
935.2
1805.2
MHz
Last Rx Channel
959.8
1879.8
MHz
Maximum Tx Power
33.0
(Class 4) (PL5)
30.0
(Class 1) (PL0)
dBm
Minimum Tx Power
5.0
(PL19)
0.0
(PL15)
dBm
Tx
Tx IF
RFLO Tx
IFLO Tx
Unit
GSM900
890-915
270
1160-1185
540
MHz
GSM1800
1710-1785
130
1580-1655
520
MHz
Rx
Rx 1st IF
Rx 2nd IF
RFLO Rx
IFLO Rx
Unit
GSM900
935-960
225
45
1160-1185
540
MHz
GSM1800
1805-1880
225
45
1580-1655
540
MHz
