Trimble GA830 Antenna dramatically improve the out of band signal rejection for the high band frequencies (1525 – 1610 MHz) through increasing the number of filters and changing the steepness of the frequency response. The changes can be seen in the frequency response plots for Zephyr 2 versus Zephyr 3 which uses the same architecture as the GA830.
The Iridium filtering on the GA830 is independent of the MSS wide/narrow band filtering.
The GA830 provides 35 dB of rejection (relative to the GPS L1 Center frequency) for the Inmarsat and Iridium signals.
Product Bulletin - Trimble Site Positioning Systems GNSS Resistance to Signal Jamming and SpoofingThe architecture for the GA830 LNA input voltage is this:
GA830 frequency band LNA switching is available based on 2 voltage ranges supplied by the GNSS receiver.
<6.0V 1525-1610MHz [Wide band]
>6.4V 1555-1610MHz [Narrow band]
The output voltage from the R750 (and other Trimble GNSS) is dependent on the antenna selection and MSS Beam selection. If GA830 is selected as the position antenna then the following MSS Beam selection will output these voltages:
Fugro CONNA: 7.5V [the only remaining North American spot beam (not global)]
All other beams (global): 5V