Global Positioning System Reference
In-Depth Information
300
L1
L2
E1
L5
E5a
E5
250
200
150
100
50
0
2
4
6
8
10
12
14
Number of channels
Fig. 6. Power consumption of the entire baseband circuit
Fig. 7 shows the power consumption for different combinations of signals where each
signal has been assumed to be using 12 channels. It is interesting to note that a GNSS
receiver designed to process all the civilian signals of GPS and Galileo would require slightly
short of one watt for the baseband hardware (using the Altera Cyclone-III family device
EP3C120F780C8), which is 38 times that of GPS L1 C/A baseband hardware.
5.3 Recommendations for the multi-GNSS baseband design
The challenges that are faced in designing the baseband hardware for a multi-GNSS receiver
can be broadly categorized into three groups
• complexity reduction challenges,
• power consumption reduction challenges, and
• resource requirement reduction challenges.
The complexity reduction challenges are not of significant concern because of the availability
of design tools that help an engineer to handle the kind of complexity present in this situation.
However, it is a good practice to have a modular design keeping in mind the scalability of the
architecture to additional signals. The complexity issues are not discussed here.
In most of the situations, the resource and power consumption are highly interrelated.
Exceptions to these situations are generally the changes in the operating frequency. Reduction
in the operating frequency will basically reduce only the power consumption though it may
indirectly reduce the resource requirement to some extent (such as a simplified clock tree or
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