Configurable radio frequency front-end to support TTC and ISL satellite links
In some implementations, a satellite may include a software-defined radio (SDR), antenna circuits, and front-end circuits. Each antenna circuit may include a first antenna and a second antenna. Each front-end circuit may be coupled between the SDR and one of the plurality of antenna circuits and may include a transmit path, a first receive path, and a second receive path. The transmit path may include an input coupled to an output of the radio and an output selectively coupled to the first antenna for ISL and TT&C transmissions. The first path includes an input to couple to the first antenna and an output to couple to the radio. The second path includes an input coupled to the second antenna and an output to couple to the radio. The front-end circuit may selectively enable one of the first or second receive paths for ISL or TT&C communications.
1 . A system comprises:
one or more satellites, wherein each satellite comprises:
a software-defined radio (SDR) configured to provide data for transmission and to process received data;
a plurality of antenna circuits, each antenna circuit including a first antenna configured to send and receive signals within a first frequency band and including a second antenna configured to receive signals within a second frequency band; and
a plurality of front-end circuits, each front-end circuit coupled between the SDR and one of the plurality of antenna circuits, each front-end circuit including:
a switch including a first node and a second node and including a third node coupled to the first antenna;
a transmit path configured to couple an output of the SDR to the first node;
a first receive path including an input coupled to the second node and including a first output;
a second receive path including an input coupled to the second antenna and including a second output; and
a multiplexer including a first input coupled to the first output, a second input coupled to the second output, and an output coupled to the SDR; and
wherein the switch and the multiplexer are controlled to configure the front-end circuit to provide one of intersatellite link (ISL) communications or telemetry, tracking, and control (TT&C) communications.
2 . The system of claim 1 , wherein the transmit path is used for both the ISL communications and the TT&C communications.
3 . The system of claim 1 , wherein the transmit path comprises:
an amplifier including an input coupled to an output of the SDR and including an output;
a filter including an input coupled to the output of the amplifier and including an output; and
a switch including a first node coupled to the output of the filter, a second node configured to couple to the first receive path, and an output coupled to the first antenna, the switch is configured to couple the first node to the output.
4 . The system of claim 1 , wherein the first receive path comprises:
a switch including a first node coupled to the transmit path, a second node, and a third node coupled to the first antenna, the switch is configured to selectively couple the third node to one of the first node or the second node;
a first amplifier including an input coupled to the second node and including an output; and
a first filter including an input coupled to the output of the first amplifier and including an output coupled to the first input of the multiplexer.
5 . The system of claim 4 , wherein the second receive path comprises:
a second amplifier including an input coupled to the second antenna and including an output; and
a second filter including an input coupled to the output of the second amplifier and including an output coupled to the second input of the multiplexer.
6 . The system of claim 5 , wherein, in an ISL communications mode:
the multiplexer is configured to couple the first input of the multiplexer to the SDR; and
the switch is configured to couple the first node to the third node during ISL transmission and to couple the second node to the third node during ISL reception.
7 . The system of claim 5 , wherein, in a TT&C communications mode:
the multiplexer is configured to couple the second input of the multiplexer to the SDR; and
the switch is configured to couple the first node to the third node.
8 . The system of claim 1 , wherein amplifiers within one of the first receive path or the second receive path that are not being utilized for communication are powered off to reduce overall power consumption and to reduce radio frequency interference with other circuits or subsystems.
9 . A satellite comprising:
a software-defined radio (SDR) configured to provide data for transmission and to process received data;
a plurality of antenna circuits, each antenna circuit including a first antenna and including a second antenna; and
a plurality of front-end circuits, each front-end circuit coupled between the SDR and one of the plurality of antenna circuits, each front-end circuit including:
a transmit path including an input coupled to an output of the SDR and an output configured to couple to the first antenna;
a first receive path including an input configured to couple to the first antenna and an output configured to couple to the SDR; and
a second receive path including an input coupled to the second antenna and including an output configured to couple to the SDR; and
wherein each front-end circuit is configured to selectively enable one of the first receive path for intersatellite link (ISL) communications or the second receive path for telemetry, tracking, and control (TT&C) communications.
10 . The satellite of claim 9 , further comprising one or more sensors configured to determine a stability parameter corresponding to stability of the satellite, wherein the front-end circuit is configured to enable the second receive path when the stability parameter is indicative of tumbling.
11 . The satellite of claim 9 , further comprising one or more sensors configured to determine a stability parameter corresponding to stability of the satellite, wherein the front-end circuit is configured to enable the first receive path when the stability parameter is indicative of stability.
12 . The satellite of claim 9 , wherein the transmit path comprises:
an amplifier including an input coupled to an output of the SDR and including an output;
a filter including an input coupled to the output of the amplifier and including an output; and
a switch including a first node coupled to the output of the filter, a second node configured to couple to the first receive path, and an output coupled to the first antenna, the switch is configured to couple the first node to the output during transmission.
13 . The satellite of claim 9 , wherein the first receive path comprises:
a switch including a first node coupled to the transmit path, a second node, and a third node coupled to the first antenna, the switch is configured to selectively couple the third node to one of the first node or the second node;
a first amplifier including an input coupled to the second node and including an output;
a first filter including an input coupled to the output of the first amplifier and including an output; and
a multiplexer including a first input coupled to a first input of the multiplexer, a second input configured to couple to an output of the second receive path, and an output coupled to the SDR.
14 . The satellite of claim 13 , wherein the second receive path comprises:
a second amplifier including an input coupled to the second antenna and including an output; and
a second filter including an input coupled to the output of the second amplifier and including the output coupled to the second input of the multiplexer.
15 . The satellite of claim 14 , wherein, in an ISL communications mode:
the transmit path is active;
amplifiers in the second receive path are powered off to reduce overall power consumption and to reduce radio frequency interference with other circuits or subsystems;
the multiplexer is configured to couple the first input of the multiplexer to the SDR; and
the switch is configured to couple the first node to the third node during ISL transmission and to couple the second node to the third node during ISL reception.
16 . The satellite of claim 14 , wherein, in a TT&C communications mode:
the transmit path is active;
amplifiers in the first receive path are powered off to reduce overall power consumption and to reduce radio frequency interference with other circuits or subsystems;
the switch is configured to couple the first node to the third node; and
the multiplexer is configured to couple the second input of the multiplexer to the SDR.
17 . A system comprises:
a plurality of satellites configured to selectively communicate with one another via intersatellite links (ISL) communication links and with a ground base station using a telemetry, tracking, and control (TT&C) communications link, wherein each satellite comprises:
a signal processing circuit;
an antenna circuit including a first antenna configured to send and receive signals within a first frequency band and a second antenna configured to receive signals within a second frequency band;
a front-end circuit comprising:
a transmission path including:
a first amplifier including an input coupled to an output of the signal processing circuit and including an output; and
a first filter including an input coupled to the output of the first amplifier and including an output;
a first receive path including:
a second amplifier including an input and including an output;
a second filter including an input coupled to the output of the second amplifier and including an output;
a switch including a first node coupled to the output of the first filter, a second node coupled to the input of the second amplifier, and a third node coupled to the first antenna;
a multiplexer including a first input coupled to the output of the second filter, a second input, and an output coupled to an input of the signal processing circuit; and
a second receive path including:
a third amplifier including an input coupled to the second antenna and including an output;
a third filter including an input coupled to the output of the third amplifier and including an output coupled to the second input of the multiplexer;
wherein the switch and the multiplexer are controlled to selectively disable one of the first receive path or the second receive path to provide one of a telemetry, tracking, and control (TT&C) mode or an intersatellite link (ISL) mode.
18 . The system of claim 17 , wherein each satellite further comprises one or more sensors configured to determine a stability parameter corresponding to stability of the satellite, wherein:
the front-end circuit is configured to enable the second receive path when the stability parameter is indicative of tumbling; and
the front-end circuit is configured to enable the first receive path when the stability parameter is indicative of stability.
19 . The system of claim 17 , wherein one of the second amplifier within the first receive path or the third amplifier within the second receive path are powered off to reduce overall power consumption and to reduce radio frequency interference with other circuits or subsystems when the one of the first receive path or the second receive path are not in use.
20 . The system of claim 18 , wherein the plurality of satellites comprises:
a mesh network configured to communicate with one another using the ISL communication links; and
wherein one or more of the plurality of satellites are configured to communicate with one or more ground base stations via a TT&C communications link; and
wherein a first satellite of the plurality of satellites has no direct connection to a ground base station and may communicate with at least one of the one or more ground base stations through one or more other satellites of the mesh network.