LEON-G100 / LEON-G200 - System Integration Manual
GSM.G1-HW-09002-G3
Preliminary
System description
Page 24 of 125
slots/bursts) with a periodicity of 4.615 ms (width of 1 frame = 8 slots/bursts), so with a 1/4 duty cycle, according
to GSM TDMA.
In the following figure is reported the current consumption profiles with 2 slots used to transmit.
Time [ms]
RX
slot
unused
slot
unused
slot
TX
slot
TX
slot
unused
slot
MON
slot
unused
slot
RX
slot
unused
slot
unused
slot
TX
slot
TX
slot
unused
slot
MON
slot
unused
slot
GSM frame
4.615 ms
(1 frame = 8 slots)
Current [A]
200mA
~170 mA
1800 mA
Peak current
depends on
TX power
~170 mA
GSM frame
4.615 ms
(1 frame = 8 slots)
1.5
1.0
0.5
0.0
2.5
2.0
~40 mA
Figure 11: Description of the VCC current consumption profile versus time during a GPRS connection (2 TX slots)
1.5.3.2
Current consumption profiles – Cyclic idle/active mode (power saving enabled)
The power saving configuration is by default disabled, but it can be enabled using the appropriate AT command
(refer to
u-blox AT Commands Manual
[2], AT+UPSV command). When the power saving is enabled, the module
automatically enters idle-mode whenever possible.
When power saving is enabled, the module is registered or attached to a network and a voice or data call is not
enabled, the module automatically enters idle-mode whenever possible, but it must periodically monitor the
paging channel of the current base station (paging block reception), in accordance to GSM system requirements.
When the module monitors the paging channel, it wakes up to active mode, to enable the reception of paging
block. In between, the module switches to idle-mode. This is known as GSM discontinuous reception (DRX).
The module processor core is activated during the paging block reception, and automatically switches its
reference clock frequency from the 32 kHz used in idle-mode to the 26 MHz used in active-mode.
The time period between two paging block receptions is defined by the network. It can vary from 470.76 ms
(width of 2 GSM multiframes = 2 x 51 GSM frames = 2 x 51 x 4.615 ms) up to 2118.42 ms (width of 9 GSM
multiframes = 9 x 51 frames = 9 x 51 x 4.615 ms): this is the paging period parameter, fixed by the base station
through broadcast channel sent to all users on the same serving cell.
An example of the current consumption profile of the data module when power saving is enabled is shown in
Figure 12: the module is registered with the network, automatically goes into idle mode and periodically wakes
up to active mode to monitor the paging channel for paging block reception (cyclic idle/active mode).