Next generation GNSS-R receiver
A system includes a navigation antenna configured to receive first satellite signals transmitted from a first type of satellite in a first frequency band and second satellite signals transmitted from a second type of satellite in a second frequency band and generate RHCP signal responses based on the first and second satellite signals, a plurality of science antennas configured to receive the first satellite signals in the first frequency band and the second satellite signals in the second frequency band as reflected from a ground surface and generate LHCP signal responses and RHCP signal responses based on the first and second satellite signals, and a receiver module including a processing module and a plurality of receivers coupled between the navigation antenna and the plurality of science antennas and the processing module. The processing module is configured to generate telemetry data based on the received LHCP and RHCP signal responses.
1 . A system configured to receive satellite signals, the system comprising:
a navigation antenna configured to (i) receive first satellite signals transmitted from a first type of satellite in a first frequency band and second satellite signals transmitted from the first type or a second type of satellite in a second frequency band, (ii) generate left hand circular polarization (LHCP) signal responses and right hand circular polarization (RHCP) signal responses based on the first and second satellite signals;
a plurality of science antennas configured to (i) receive the first satellite signals in the first frequency band and the second satellite signals in the second frequency band as reflected from a ground surface and (ii) generate LHCP signal responses and RHCP signal responses based on the first and second satellite signals; and
a receiver module including
a processing module, and
a plurality of receivers coupled between (i) the navigation antenna and the plurality of science antennas and (ii) the processing module,
wherein the processing module is configured to receive the LHCP signal responses and the RHCP signal responses from the navigation antenna and the plurality of science antennas via the plurality of receivers and generate telemetry data based on the received LHCP and RHCP signal responses,
wherein the processing module includes a logic module configured to process the LHCP signal responses and the RHCP signal responses to provide digital signal pre-conditioning and channel correlation.
2 . The system of claim 1 , wherein:
the processing module includes a system on a chip (SOC) comprising first and second processor cores and field programmable gate array (FPGA) logic configured to process the LHCP signal responses and the RHCP signal responses received from the navigation antenna and the plurality of science antennas,
the logic module provides processed correlated data to the first and second processor cores.
3 . The system of claim 2 , wherein:
the receiver module includes an oscillator; and
the processing module includes a sampler configured to sample the LHCP and RHCP signal responses transmitted from the navigation antenna and the plurality of science antennas,
wherein the sampler is configured to generate data packets from sampling the LHCP and RHCP signal responses in accordance with a clock signal generated with the oscillator,
wherein the processing module is configured pass the data packets through a processing loop having a channel selection multiplexer, a Doppler mixer, and a quadrature encoder.
4 . The system of claim 3 , wherein the receiver module includes a command and data handling (CDH) module configured to receive the telemetry data from the processing module and transmit the telemetry data from the receiver module, wherein the CDH module is configured to:
control power distribution to the receiver module with a power control module that receives power from a power source external to the receiver module;
control firmware and software updates, perform instrument housekeeping functions, and monitor system parameters for the receiver module; and
provide configuration information and uplinked commands to the processing module.
5 . The system of claim 2 , wherein the first and second processor cores are configured to process the correlated data according to a reflection measurement process, a low-level navigation process, and a high-level navigation process.
6 . The system according to claim 5 , wherein the first and second processor cores are configured to implement an internal receiver dynamics model and a transmitter dynamics model based on processing the correlated data according to the reflection measurement process, the low-level navigation process, and the high-level navigation process, wherein the internal receiver dynamics model is configured to predict an upcoming receiver position and the transmitter dynamics model is configured to predict satellite geometry information.
7 . The system according to claim 6 , wherein the first and second processor cores are configured to perform measurement scheduling based on the receiver position and the satellite geometry information to predict specular points, assign a figure-of-merit to potential measurements, select measurements to perform, and formulate an open-loop correlator command.
8 . The system of claim 1 , further comprising low noise amplifiers arranged between (i) the navigation antenna and the plurality of science antennas and (ii) the plurality of receivers.
9 . The system of claim 1 , wherein the first satellite signals correspond to global positioning system (GPS) satellite signals and the second satellite signals correspond to Galileo satellite signals.
10 . The system of claim 1 , wherein the first frequency band is an L1/E1 frequency band and the second frequency band is an L5/E5 frequency band.
11 . The system of claim 1 , wherein each of the plurality of receivers is configured to operate in at least two channels corresponding respectively to the first frequency band and the second frequency band.
12 . The system of claim 1 , further comprising an antenna module that includes the plurality of science antennas.
13 . The system of claim 12 , wherein each of the plurality of science antennas includes:
a substrate supporting a printed circuit board layer that includes first and second output ports; and
first and second feeding pins extending from the printed circuit board layer, the first and second feeding pins configured to carry LHCP and RHCP signal responses output from the first and second output ports, respectively.
14 . The system of claim 13 , wherein each of the plurality of science antennas further includes a parasitic pin extending from the printed circuit board layer.
15 . The system of claim 13 , wherein the antenna module comprises:
a mounting board; and
a feeding network comprised of microstrip traces arranged on or embedded within the mounting board,
wherein the first and second feeding pins of each of the plurality of science antennas are coupled to the feeding network and extend from a device mounting panel through the substrate to the printed circuit board layer.
16 . The system of claim 15 , wherein the feeding network includes an LHCP path coupled to the first feeding pins and an RHCP path coupled to the second feeding pins.
17 . The system of claim 15 , further comprising a spacer layer arranged between the mounting board and the device mounting panel to electrically isolate the feeding network from a ground plane of the device mounting panel.
18 . The system of claim 17 , wherein the spacer layer includes channels defined around traces of the feeding network.
19 . The system of claim 17 , wherein the spacer layer is honeycombed.
20 . A system configured to receive satellite signals, the system comprising:
a navigation antenna configured to (i) receive first satellite signals transmitted from a first type of satellite in a first frequency band and second satellite signals transmitted from the first type or a second type of satellite in a second frequency band and (ii) generate left hand circular polarization (LHCP) signal responses and right hand circular polarization (RHCP) signal responses based on the first and second satellite signals;
a plurality of science antennas configured to (i) receive the first satellite signals in the first frequency band and the second satellite signals in the second frequency band as reflected from a ground surface and (ii) generate LHCP signal responses and RHCP signal responses based on the first and second satellite signals;
a receiver module including
a processing module, and
a plurality of receivers coupled between (i) the navigation antenna and the plurality of science antennas and (ii) the processing module, wherein each of the plurality of receivers is configured to operate in at least two channels corresponding respectively to the first frequency band and the second frequency band; and
low noise amplifiers arranged between (i) the navigation antenna and the plurality of science antennas and (ii) the plurality of receivers,
wherein the processing module is configured to receive the LHCP signal responses and the RHCP signal responses from the navigation antenna and the plurality of science antennas via the plurality of receivers and generate telemetry data based on the received LHCP and RHCP signal responses,
wherein the processing module includes a system on a chip (SOC) comprising first and second processor cores and field programmable gate array (FPGA) logic configured to process the LHCP signal responses and the RHCP signal responses received from the navigation antenna and the plurality of science antennas,
wherein the processing module includes a logic module configured to process the LHCP signal responses and the RHCP signal responses to provide channel correlation,
wherein the first and second processor cores are configured to process correlated data from the logic module according to a reflection measurement process, a low-level navigation process, and a high-level navigation process,
wherein the first and second processor cores are configured to implement an internal receiver dynamics model and a transmitter dynamics model based on processing the correlated data according to the reflection measurement process, the low-level navigation process, and the high-level navigation process, wherein the internal receiver dynamics model is configured to predict an upcoming receiver position and the transmitter dynamics model is configured to predict satellite geometry information, and
wherein the first and second processor cores are configured to perform measurement scheduling based on the upcoming receiver position and the satellite geometry information to predict specular points, assign a figure-of-merit to potential measurements, select measurements to perform, and formulate an open-loop correlator command.