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Iridium Satellite LLC
9601 SBD Transceiver Product Developers Guide
V1.24 120505
3.2.2 Typical Power Profile
This section is designed to give the application developer some insight to the electrical power profile that
the 9601 uses. It does not describe every situation and permutation possible. It should be used as a
starting point for the application developer to continue their own development design. The actual usage
profile can vary for a number of reasons:
1) View of the sky –if in poor visibility of the sky where a clear line of sight is not available between
the transceiver and the satellite.
2) The higher the VSWR the higher the current consumed
3) Application programming
4) Possible manufacturing variation from transceiver to transceiver. [I.e. the transceiver still meets
specification, but over a large sample size some may operate better than average.]
The application designer should be sure not to use best case numbers for average, expected or worse
case scenarios. Figure 11 provides a graphical representation of the typical supply current profile of a
9601 SBD Transceiver sending and receiving SBD messages.
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
Transmit burst
preparation
0.5
0.4
0.3
0.2
0.1
0
-10
0
Description:
(A) Transmit burst preparation: As the 9601 gets ready to send the data burst, it turns on various parts
of the transmitter chain and transfers the message into the DSP to be formatted for transmission. This
first part of the pulse is nominally 170mA and lasts for 4mS.
(B) Transmitter data burst: The final part of the preparation stage is to power up the power amplifier
(PA). Once power is available, and synchronized to the system framing, the formatted burst is clocked
into the DAC, which causes the PA to draw the high current pulse. This pulse is 9mS long, but the
amplitude is variable upon the RF matching into the antenna. Generally a high VSWR will use more
current. For example, into an open circuit antenna port, the 9601 can use between 1.4A and 2A,
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Information contained herein is subject to change without further notice
Transmitter data burst
(The amplitude of this
pulse is determined by
PA efficiency but mostly
by antenna matching.
The amplitude can
reach 2A )
Background
operating
current
10
20
Time (mS)
Figure 11 –Typical Supply Current Profile
Receiver data burst.
(This has constant amplitude,
however it gets longer when
the data module is initially
searching for the network.)
30
40
50
60
70
19
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