Patent Publication Number: US-11652502-B2

Title: Bi-directional single-ended transmission systems

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/983,619, which was filed on Aug. 3, 2020. The content of the foregoing application is incorporated herein by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to bi-directional single-ended transmission systems. 
     BACKGROUND 
     A conventional CoaXPress (CXP) interface may include expensive external off-the-shelf PHYs at front ends of the transceivers. For example, some power-over-coax systems use an application specific integrated circuit (ASIC) with an external cable driver/equalizer to implement a CXP interface. As used herein, CXP refers to the CoaXPress standard for communications over a coaxial cable. 
     SUMMARY 
     Disclosed herein are implementations of bi-directional single-ended transmission systems. 
     In a first aspect, the subject matter described in this specification can be embodied in systems that include a receiver with a first differential input terminal and a second differential input terminal, wherein the first differential input terminal is coupled to a first node and the second differential input terminal is coupled to a second node; a transmitter with an output terminal coupled to a third node; a first inductor connected between the first node and the third node; a second inductor connected between the second node and the third node; and a shunt resistor connected between the third node and a ground node. 
     In a second aspect, the subject matter described in this specification can be embodied in systems that include a transmitter with a first differential output terminal and a second differential output terminal, wherein the first differential output terminal is coupled to a first node and the second differential output terminal is coupled to a second node; a receiver with an input terminal coupled to a third node; and an inductor and a resistor connected in series between the first node and the third node. 
     In a third aspect, the subject matter described in this specification can be embodied in systems that include a coaxial cable including an inner conductor and an outer conductor; a first receiver with a first differential input terminal and a second differential input terminal, wherein the first differential input terminal is coupled to a first node, which is coupled to the inner conductor, and the second differential input terminal is coupled to a second node; a first transmitter with a first differential output terminal and a second differential output terminal, wherein the first differential output terminal is coupled to a third node, which is coupled to the inner conductor, and the second differential output terminal is coupled to a fourth node; a second transmitter with an output terminal coupled to a fifth node; a first inductor connected between the first node and the fifth node; a second inductor connected between the second node and the fifth node; a first resistor connected between the fifth node and a ground node; a second receiver with an input terminal coupled to a sixth node; and a third inductor and a second resistor connected in series between the third node and the sixth node. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Described herein are systems and methods for bi-directional single-ended transmission. 
       The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG.  1    is a block diagram of an example of a system for bi-directional single-ended transmission. 
         FIG.  2    is a circuit diagram of an example of a system including low-speed injection circuitry. 
         FIG.  3    is a circuit diagram of an example of a system including low-speed extraction circuitry. 
         FIG.  4    is a circuit diagram of an example of a system for bi-directional single-ended transmission. 
         FIG.  5    is a graph of examples of low-speed voltage signals with different levels of baseline wander distortion. 
         FIG.  6    is a circuit diagram of an example of a system including passives for connecting a power-over-coax power source to a coaxial cable with drawings of example components. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are systems and methods for bi-directional single-ended transmission. These systems may provide a bi-directional single-ended power-over-coax link (BSPL). For example, these systems and methods may be used to provide a CoaXPress (CXP) interface. These systems may use software that implements a standard CXP protocol for communications between devices over a coaxial cable. In some implementations, a BSPL compute side interface may be compatible with an off-the-shelf CXP sensor. The hardware implementations of some systems may use relatively less expensive external passive components in low-speed injection circuitry, low-speed extraction circuitry, high-pass filters and amplifiers, rather than expensive off-the-shelf PHY solutions. 
     Some implementations of the systems and methods describe herein may provide advantages, such as, better low-speed uplink signal integrity with baseline wander correction, better low-speed uplink signal integrity with reduced worst-case coupling noise at the uplink receiver, and/or better high-speed downlink signal integrity, with noise coupling reduction through use of a high-pass filter at a downlink receiver. 
       FIG.  1    is a block diagram of an example of a system  100  for bi-directional single-ended transmission. The system  100  includes a sensor device  102  and a compute device  104  that are connected via a coaxial cable  110 . The coaxial cable  110  attaches to a coaxial connector  112  of the sensor device  102  and to a coaxial connector  114  of the compute device  104 . The system  100  includes a power-over-coax direct current injector  120 , in the compute device  104 , and a power-over-coax direct current extractor  122 , in the sensor device  102 . The power-over-coax direct current extractor  122  and the power-over-coax direct current injector  120  are coupled to a conductor of the coaxial cable  110  via passives  124  and  126 . The system  100  includes a sensor  130 , in the sensor device  102 , and a system-on-a-chip (SOC)  132 , in the compute device  104 , that is configured to control and process sensor data from the sensor  130 . The system  100  includes a high-speed transmitter  140 , in the sensor device  102 , configured to transmit data via the coaxial cable  110  to a high-speed receiver  142 , in the compute device  104 . The system  100  includes a low-speed transmitter  144 , in the compute device  104 , configured to transmit data via the coaxial cable  110  to a low-speed receiver  146 , in the sensor device  102 . In the compute device  104 , the low-speed transmitter  144  is coupled to the communication channel via a low-speed injection circuitry  150 , while the high-speed receiver  142  is coupled to the communication channel via a high-pass filter  160 . In the sensor device  102 , the low-speed receiver  146  is coupled to the communication channel via a low-speed extraction circuitry  170  and an amplifier  180 . 
     The system  100  includes a coaxial cable  110  including an inner conductor and an outer conductor. The coaxial cable  110  is connected between the sensor device  102  and the compute device  104 . For example, the coaxial cable  110  may have a characteristic impedance of 50 Ohms. The coaxial cable  110  connects to these devices at their respective coaxial connectors  112  and  114 . For example, the coaxial connector  112  and the coaxial connector  114  may be HFM connectors, or any coaxial cable connectors that are impedance matched to the coaxial cable  110 . The inner conductor of the coaxial cable  110  may be coupled to a first node  152  in the compute device  104  and to a third node  172  in the sensor device  102 . 
     The system  100  includes a power-over-coax direct current injector  120  coupled to the first node  152 . The power-over-coax direct current injector  120  may supply current (e.g., 0.9 Amps or 2 Amps direct current) that may flow through the coaxial cable  110  to the sensor device  102  that is powered by this supplied current. The power-over-coax direct current injector  120  is coupled to the first node  152  via passives  126  and a DC block  127 . For example, the passives  126  may be an 8 microhenry inductor. 
     The system  100  includes a power-over-coax direct current extractor  122  coupled to the third node  172 . The power-over-coax direct current extractor  122  may draw current (e.g., 0.9 Amps, 1.5 Amps, or 2 Amps direct current) that may flow through the coaxial cable  110  from the compute device  104  that supplies power to the sensor device  102 . The power-over-coax direct current extractor  122  is coupled to the third node  172  via passives  124  and a DC block  125 . For example, the passives  124  may be an 8 microhenry inductor. 
     The system  100  includes a high-speed transmitter  140  with a first differential output terminal and a second differential output terminal. The first differential output terminal is coupled to the third node  172  and the second differential output terminal is coupled to a fourth node  174 . For example, the high-speed transmitter  140  may be configured to transmit differential signals, such as Low-Voltage Differential Signaling (LVDS), across the first differential output terminal and a second differential output terminal. In some implementations, the high-speed transmitter  140  is configured to transmit differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed transmitter  140  is configured to transmit CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. For example, the high-speed transmitter  140  may read data (e.g., image data or other sensor data) for transmission from the sensor  130  (e.g., an image sensor, a radar sensor, a lidar sensor, or another type of sensor) via a native interface (e.g., an LVDS/Mobile Industry Processor Interface (MIPI)/display port (DP) interface). 
     The system  100  includes a high-speed receiver  142  with a first differential input terminal  162  and a second differential input terminal  164 . The first differential input terminal  162  is coupled to the first node  152  and the second differential input terminal  164  is coupled to a second node  154 . For example, the high-speed receiver  142  may be configured to receive differential signals, such as Low-Voltage Differential Signaling (LVDS), appearing between the first differential input terminal  162  and the second differential input terminal  164 . In some implementations, the high-speed receiver  142  is configured to receive differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed receiver  142  is configured to receive CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. For example, the high-speed receiver  142  may in turn pass received data (e.g., image data or other sensor data) to the system-on-a-chip  132  via a serial bus interface (e.g., a Peripheral Component Interconnect Express (PCIe) Gen 4 bus). 
     The system  100  includes a low-speed transmitter  144  with an output terminal  166  coupled to a fifth node. For example, the low-speed transmitter  144  may generate signals at the output terminal  166  using Low-Voltage Complementary Metal Oxide Semiconductor (LVCMOS). For example, the high-speed receiver  142  may be configured to operate at a higher carrier frequency than the low-speed transmitter  144 . In some implementations, the low-speed transmitter  144  is configured to transmit CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for the sensor device  102  connected via the coaxial cable  110 . For example, the low-speed transmitter  144  may read data (e.g., control data, firmware, or triggering data) for transmission from the system-on-a-chip  132  via a serial bus interface (e.g., a Peripheral Component Interconnect Express (PCIe) Gen 4 bus). In some implementations, the low-speed transmitter  144  and the high-speed receiver  142  are implemented in a single application specific integrated circuit (ASIC) in the compute device  104 . 
     The system  100  includes a low-speed receiver  146  with an input terminal  182  coupled to a sixth node  176 . The system includes an amplifier  180  coupling the sixth node  176  to the input terminal  182 . For example, the low-speed receiver  146  may receive signals at the input terminal  182  using Stub Series Terminated Logic (SSTL). In some implementations, the low-speed receiver  146  is configured to receive CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for the sensor device  102 . For example, the low-speed receiver  146  may in turn pass received data (e.g., control data, firmware, or triggering data) to the sensor  130  via a native interface (e.g., an LVDS/Mobile Industry Processor Interface MIPI)/display port (DP) interface). In some implementations, the low-speed receiver  146  and the high-speed transmitter  140  are implemented in a single application specific integrated circuit (ASIC) in the sensor device  102 . 
     For example, the high-speed transmitter  140  and the high-speed receiver  142  may be configured to operate at a higher carrier frequency than the low-speed transmitter  144  and the low-speed receiver  146 . In some implementations, the high-speed transmitter  140  and the high-speed receiver  142  are configured to transfer CoaXPress high-speed downlink signals and the low-speed transmitter  144  and the low-speed receiver  146  are configured to transmit CoaXPress low-speed uplink signals 
     The system  100  includes a low-speed injection circuitry  150  that couples the output terminal  166  of the low-speed transmitter  144  to the first node  152  and the second node  154  to enable the transmission of low-speed signals over the coaxial cable  110  concurrent with reception of high-speed signals by the high-speed receiver  142  and supply of power by the power-over-coax direct current injector  120 . In some implementations, the electrical parameters of the low-speed injection circuitry  150  may be chosen to correct or mitigate baseline wander caused primarily by the power-over-coax direct current injector  120  and/or its passives  126 . For example, the low-speed injection circuitry  150  may be the low-speed injection circuitry  240  of  FIG.  2   . The electrical parameters of the low-speed injection circuitry  150  may result in a sufficiently long RL time constant (e.g., 1200 nanoseconds) to mitigate signal integrity degradation of the low-speed signals by baseline wander. 
     The system  100  includes a high-pass filter  160  coupling the first differential input terminal  162  to the first node  152  and coupling the second differential input terminal  164  to the second node  154 . Asymmetry between the differential pair may generate low-speed noise at the high-speed receiver  142 , which may propagate from the low-speed transmitter  144  to the high-speed receiver  142 . For example, asymmetry may be caused by “Cable vs 50 ohm” impedance mismatch, the passives  126 , and/or component tolerances in the circuitry of the compute device  104 . The high-pass filter  160  may filter out this low-speed noise coupling, resulting in better high-speed signal integrity. For example, the high-pass filter  160  may be the high-pass filter  230  of  FIG.  2   . 
     The system  100  includes a low-speed extraction circuitry  170  that couples signals from the third node  172  to the sixth node  176 . In some implementations, the fourth node  174  is isolated from the sixth node  176 . The low-speed extraction circuitry  170  may have an unbalanced structure, which may provide better low-speed signal integrity than balanced topologies. For example, the low-speed extraction circuitry  170  may be the low-speed extraction circuitry  340  of  FIG.  3   . 
       FIG.  2    is a circuit diagram of an example of a system  200  including low-speed injection circuitry  240 . The system  200  includes a cable connector with a first conductor  202  coupled to a first node  204  and a second node  206  coupled via a termination resistor  208  to a ground node. The system  200  includes a power-over-coax direct current injector  210  coupled to the first node  204 ; a first differential input terminal  220  and a second differential input terminal  222  for a receiver; an output terminal  224  for a transmitter; a first capacitor  232  connected between the first differential input terminal  220  and the first node  204 ; a second capacitor  234  connected between the second differential input terminal  222  and the second node  206 ; and the low-speed injection circuitry  240  that couples the output terminal  224  to the first node  204  and the second node  206 . The low-speed injection circuitry  240  includes a third node  250  coupled to the output terminal  224 ; a first inductor  260  connected between the first node  204  and the third node  250 ; a second inductor  262  connected between the second node  206  and the third node  250 ; a shunt resistor  270  connected between the third node  250  and a ground node; and an output capacitor  280  connected between the third node  250  and a ground node. For example, the low-speed injection circuitry  240  may be used inject low-speed signals from the transmitter onto the first conductor  202  of the cable connector, while high-speed signals are received by the receiver. 
     The system  200  includes a receiver (e.g., the high-speed receiver  142 ) with a first differential input terminal  220  and a second differential input terminal  222 . The first differential input terminal  220  is coupled to a first node  204  and the second differential input terminal  222  is coupled to a second node  206 . For example, the receiver may be configured to receive differential signals, such as Low-Voltage Differential Signaling (LVDS), appearing between the first differential input terminal  220  and the second differential input terminal  222 . In some implementations, the receiver is configured to receiver differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the receiver is configured to receive CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. 
     The system  200  may include a high-pass filter  230  coupling the first differential input terminal  220  to the first node  204  and coupling the second differential input terminal  222  to the second node  206 . In this example, the high-pass filter  230  includes a first capacitor  232  connected between the first differential input terminal  220  and the first node  204 ; and a second capacitor  234  connected between the second differential input terminal  222  and the second node  206 . For example, the first capacitor  232  may be a 33 picofarad capacitor. For example, the second capacitor  234  may be a 33 picofarad capacitor. 
     The system  200  includes a coaxial cable connector with a first conductor  202  coupled to the first node  204 . In this example, the first conductor  202  is coupled to the first node  204  via a first DC block capacitor  215 . For example, when connected to a coaxial cable, the first conductor  202  may be connected to an inner conductor of the coaxial cable. The coaxial cable connector also includes a termination resistor  208  (e.g., 50 Ohms) that is connected to a ground node. For example, the coaxial cable connector may be an HFM connector, or any coaxial cable connector that is impedance matched to the coaxial cable to be used. 
     The system  200  includes a DC block  214 . The DC block  214  may serve to isolate the high-speed receiver, low-speed transmitter, and LSI circuits from the high DC current (e.g., 2 Amps) from the power-over-coax direct current injector  210 . The DC block  214  includes a first DC block capacitor  215  (e.g., a 100 nanofarad capacitor), which is connected between the first conductor  202  of the coaxial cable connector and the first node  204 , and a second DC block capacitor  216  (e.g., a 100 nanofarad capacitor), which is connected between the termination resistor  208  and the second node  206 . These two capacitors of the DC block  214  may balance between node  204  and node  206 . 
     The system  200  includes a power-over-coax direct current injector  210  coupled to the first node  204 . The power-over-coax direct current injector  210  may supply current (e.g.,  2 A direct current) that may flow through a coaxial cable connected to the coaxial cable connector to a sensor device (e.g., the sensor device  102 ) that is powered by this supplied current. The power-over-coax direct current injector  210  is coupled to the first node  204  via a power inductor  212  and the DC block capacitor  215 . For example, the power inductor  212  may be an 8 microhenry inductor. 
     The system  200  includes a transmitter with an output terminal  224  coupled to a third node  250 . In this example, the output terminal  224  is connected to the third node  250 . For example, the receiver may be configured to operate at a higher carrier frequency than the transmitter. In some implementations, the transmitter is configured to transmit CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for a sensor device connected via a coaxial cable. 
     The output terminal  224  of the transmitter is coupled to the first node  204  and the second node  206  via a low-speed injection circuitry  240  to enable the transmission of low-speed signals over a coaxial cable attached to the coaxial cable connector concurrent with reception of high-speed signals by the receiver and supply of power by the power-over-coax direct current injector  210 . The low-speed injection circuitry  240  includes a first inductor  260  connected between the first node  204  and the third node  250 ; a second inductor  262  connected between the second node  206  and the third node  250 ; a shunt resistor  270  connected between the third node  250  and a ground node; and an output capacitor  280  connected between the third node  250  and a ground node. The electrical parameters of the low-speed injection circuitry  240  may be chosen to correct or mitigate baseline wander caused primarily by the power inductor  212 . For example, the first inductor  260  and the second inductor  262  may be 700 nanohenry inductors. For example, the shunt resistor  270  may be a 4 Ohm resistor. For example, the output capacitor  280  may be a 100 picofarad capacitor. The electrical parameters of the low-speed injection circuitry  240  may result in a sufficiently long RL time constant (e.g., 1200 nanoseconds) to mitigate signal integrity degradation of the low-speed signals by baseline wander. For example, baseline wander may be mitigated as illustrated in  FIG.  5   . The baseline wander correction may improve low-speed uplink eye margin. 
       FIG.  3    is a circuit diagram of an example of a system  300  including low-speed extraction circuitry. The system  300  includes a power-over-coax system  302  including a coaxial cable and termination resistors  304  and  306  at the ends of the coaxial cable. The system  300  includes a high-speed transmitter  310 ; a high-speed receiver  312 ; a low-speed transmitter  314 ; and a low-speed receiver  316  that are collectively configured to transfer data in both directions via the coaxial cable. The system  300  includes a high-pass filter  330  coupling differential input terminals of the high-speed receiver  312  to the power-over-coax system  302 ; a low-speed extraction circuitry  340  and an amplifier  350  connected in series between the power-over-coax system  302  and the low-speed receiver  316 ; and a low-speed injection circuitry  360  coupling the low-speed transmitter  314  to the power-over-coax system  302 . 
     The system  300  includes a power-over-coax system  302  including a coaxial cable with a termination resistor  304  and a termination resistor  306  at the ends of the coaxial cable coupling to ground terminals. The termination resistor  304  and the termination resistor  306  may be impedance matched to the coaxial cable of the power-over-coax system  302 . For example, the power-over-coax system  302  may include the coaxial cable  110 , the coaxial connector  112 , the coaxial connector  114 , the power-over-coax injector  120 , and the power-over-coax direct current extractor  122 . 
     The system  300  includes a high-speed transmitter  310  with a first differential output terminal and a second differential output terminal. The first differential output terminal is coupled to a first node  320  and the second differential output terminal is coupled to a second node  322 . The high-speed transmitter  310  may be configured to transmit signals through the power-over-coax system  302 . For example, the power-over-coax system  302  may include a coaxial cable connector (e.g., the coaxial cable connector  112 ) with a first conductor coupled to the first node  320 . In some implementations, the power-over-coax system  302  may include a power-over-coax direct current extractor (e.g., the power-over-coax direct current extractor  122 ) coupled to the first node  320 . For example, the high-speed transmitter  310  may be configured to transmit differential signals, such as Low-Voltage Differential Signaling (LVDS), across the first differential output terminal and a second differential output terminal. In some implementations, the high-speed transmitter  310  is configured to transmit differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed transmitter  310  is configured to transmit CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. For example, the high-speed transmitter  310  may be the high-speed transmitter  140  of  FIG.  1   . 
     The system  300  includes a low-speed receiver  316  with an input terminal coupled to a third node  342 . For example, the high-speed transmitter  310  may be configured to operate at a higher carrier frequency than the low-speed receiver  316 . The system includes an amplifier  350  coupling the third node  342  to the input terminal of the low-speed receiver  316 . For example, the amplifier  350  may include an operational amplifier. For example, the low-speed receiver  316  may receive signals at the input terminal using Stub Series Terminated Logic (SSTL). In some implementations, the low-speed receiver  316  is configured to receive CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the low-speed receiver  316  may be the low-speed receiver  146  of  FIG.  1   . 
     The system  300  includes an inductor  344  and a resistor  346  connected in series between the first node  320  and the third node  342 . The inductor  344  and the resistor  346  are components of a low-speed extraction circuitry  340  that is configured to couple signals from the first node  320  of the differential pair ( 320  and  322 ) to the low-speed receiver  316 . For example, the second node  322  may be isolated from the third node  342 . The low-speed extraction circuitry  340  may provide advantages over conventional power-over-coax terminal topologies. For example, the low-speed extraction circuitry  340  with an unbalanced structure may have better low-speed signal integrity comparing to alternative topologies with balanced connections to both nodes of the differential pair ( 320  and  322 ) used by the high-speed transmitter  310 . Balanced topologies may suffer from significant noise coupling from a high-speed transmitter to a low-speed amplifier input caused by component tolerances. The unbalanced structure of the low-speed extraction circuitry  340  may provide more immunity to high-speed noise coupling (e.g., worst-case noise coupling may be decreased from 100 mV to 25 mV). The inclusion of the inductor  344  may provide low-pass filtering to further reduce noise coupling from the high-speed transmitter  310 . For example, the inductor  344  may be a 900 nanohenry inductor. For example, the resistor  346  may be a 280 Ohm resistor. 
     The system  300  includes a high-speed receiver  312  with a first differential input terminal and a second differential input terminal. The first differential input terminal is coupled to a fourth node  324  and the second differential input terminal is coupled to a fifth node  326 . The high-speed receiver  312  may be configured to receive signals transmitted through the power-over-coax system  302  by the high-speed transmitter  310 . For example, the high-speed receiver  312  may be configured to receive differential signals, such as Low-Voltage Differential Signaling (LVDS), appearing between the first differential input terminal and the second differential input terminal. In some implementations, the high-speed receiver  312  is configured to receive differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed receiver  312  is configured to receive CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. 
     The system  300  includes a high-pass filter  330  coupling the first differential input terminal to the fourth node  324  and coupling the second differential input terminal to the fifth node  326 . In this example, the high-pass filter  330  includes a first capacitor  332  connected between the first differential input terminal and the fourth node  324 ; and a second capacitor  334  connected between the second differential input terminal and the fifth node  326 . 
     The system  300  includes a low-speed transmitter  314  with an output terminal coupled to a sixth node  370 . For example, the low-speed transmitter  314  may generate signals at the output terminal using Low-Voltage Complementary Metal Oxide Semiconductor (LVCMOS). For example, the high-speed receiver  312  may be configured to operate at a higher carrier frequency than the low-speed transmitter  314 . In some implementations, the low-speed transmitter  314  is configured to transmit CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for a sensor device (e.g., the sensor device  102 ) connected via the power-over-coax system  302 . 
     The output terminal of the low-speed transmitter  314  is coupled to the fourth node  324  and the fifth node  326  via a low-speed injection circuitry  360  to enable the transmission of low-speed signals through the power-over-coax system  302  concurrent with reception of high-speed signals by the high-speed receiver  312  and supply of power by the power-over-coax system  302 . The low-speed injection circuitry  360  includes a second inductor  362  connected in series with a second resistor  366  between the fourth node  324  and the sixth node  370 ; and a third inductor  364  connected in series with a third resistor  368  between the fifth node  326  and the sixth node  370 . The low-speed injection circuitry  360  may use a balanced structure with respect to the differential pair ( 324  and  326 ). For example, the second inductor  362  and the third inductor  364  may be 590 nanohenry inductors. For example, the second resistor  366  and the third resistor  368  may be 348 Ohm resistors. The electrical parameters of the low-speed injection circuitry  360  may result in a relatively short RL time constant (e.g., 120 nanoseconds), which may make the low-speed injection circuitry  360  more susceptible to baseline wander than the low-speed injection circuitry  240  of  FIG.  2   . 
     Asymmetry between the differential pair ( 324  and  326 ) may generate low-speed noise at high-speed receiver  312 , which may propagate from the low-speed transmitter  314  to the high-speed receiver  312 . For example, asymmetry may be caused by an impedance mismatch in the power-over-coax system  302  and/or component tolerances in the circuitry of the low-speed injection circuitry  360 . The high-pass filter  330  may filter out this low-speed noise coupling, resulting in better high-speed signal integrity. 
       FIG.  4    is a circuit diagram of an example of a system  400  for bi-directional single-ended transmission. The system  400  includes a sensor device  402  and a compute device  404  that are connected via a coaxial cable  410 . The coaxial cable  410  attaches to a coaxial connector  412  of the sensor device  402  and to a coaxial connector  414  of the compute device  404 . The system  400  includes a power-over-coax direct current injector  420 , in the compute device  404 , and a power-over-coax direct current extractor  422 , in the sensor device  402 . The power-over-coax direct current extractor  422  and the power-over-coax direct current injector  420  are coupled to a conductor of the coaxial cable  410  via passives  424  and  426 . The system  400  includes a sensor  430 , in the sensor device  402 , and a system-on-a-chip (SOC)  432 , in the compute device  404 , that is configured to control and process sensor data from the sensor  430 . The system  400  includes a high-speed transmitter  440 , in the sensor device  402 , configured to transmit data via the coaxial cable  410  to a high-speed receiver  442 , in the compute device  404 . The system  400  includes a low-speed transmitter  444 , in the compute device  404 , configured to transmit data via the coaxial cable  410  to a low-speed receiver  446 , in the sensor device  402 . In the compute device  404 , the low-speed transmitter  444  is coupled to the communication channel via a low-speed injection circuitry, including a first inductor  450 ; a second inductor  451 ; and a first resistor  453 , while the high-speed receiver  442  is coupled to the communication channel via a high-pass filter, including a first capacitor  460  and a second capacitor  461 . In the sensor device  402 , the low-speed receiver  446  is coupled to the communication channel via a low-speed extraction circuitry, including a third inductor  470  and a second resistor  471 , and an amplifier  480 . The system  400  may provide advantages over conventional power-over-coax terminal topologies. For example, the system  400  may provide better low-speed uplink signal integrity due to baseline wander correction implemented with the low-speed injection circuitry. For example, the system  400  may provide better high-speed downlink signal integrity due to noise coupling reduction implemented with the high-pass filter. 
     The system  400  includes a coaxial cable  410  including an inner conductor and an outer conductor. The coaxial cable  410  is connected between the sensor device  402  and the compute device  404 . For example, the coaxial cable  410  may have a characteristic impedance of 50 Ohms. The coaxial cable  410  connects to these devices at their respective coaxial connectors  412  and  414 . For example, the coaxial connectors  412  and the coaxial connectors  414  may be HFM connectors, or any coaxial cable connectors that are impedance matched to the coaxial cable  410 . The inner conductor of the coaxial cable  410  may be coupled to a first node  452  in the compute device  404  and to a third node  472  in the sensor device  402 . 
     The system  400  includes a power-over-coax direct current injector  420  coupled to the first node  452 . The power-over-coax direct current injector  420  may supply current (e.g., 0.9 Amps or 2 Amps direct current) that may flow through the coaxial cable  410  to the sensor device  402  that is powered by this supplied current. The power-over-coax direct current injector  420  is coupled to the first node  452  via passives  426 , a DC block  421 , and an ESD diode  423 . For example, the passives  426  may be an 8 microhenry inductor. 
     The system  400  includes a power-over-coax direct current extractor  422  coupled to the third node  472 . The power-over-coax direct current extractor  422  may draw current (e.g., 0.9 Amps or 2 Amps direct current) that may flow through the coaxial cable  410  from the compute device  404  that supplies power to the sensor device  402 . The power-over-coax direct current extractor  422  is coupled to the third node  472  via passives  424 , a DC block  425 , and an ESD diode  427 . For example, the passives  424  may be an 8 microhenry inductor. 
     The system  400  includes a high-speed transmitter  440  with a first differential output terminal and a second differential output terminal. The first differential output terminal is coupled to the third node  472  and the second differential output terminal is coupled to a fourth node  474 . For example, the high-speed transmitter  440  may be configured to transmit differential signals, such as Low-Voltage Differential Signaling (LVDS), across the first differential output terminal and a second differential output terminal. In some implementations, the high-speed transmitter  440  is configured to transmit differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed transmitter  440  is configured to transmit CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. For example, the high-speed transmitter  440  may read data (e.g., image data or other sensor data) for transmission from the sensor  430  (e.g., an image sensor or another type of sensor) via a native interface (e.g., an LVDS/Mobile Industry Processor Interface MIPI)/display port (DP) interface). 
     The system  400  includes a high-speed receiver  442  with a first differential input terminal  462  and a second differential input terminal  464 . The first differential input terminal  462  is coupled to the first node  452  and the second differential input terminal  464  is coupled to a second node  454 . For example, the high-speed receiver  442  may be configured to receive differential signals, such as Low-Voltage Differential Signaling (LVDS), appearing between the first differential input terminal  462  and the second differential input terminal  464 . In some implementations, the high-speed receiver  442  is configured to receive differential signals with a voltage swing level of approximately 1 Volt. In some implementations, the high-speed receiver  442  is configured to receive CoaXPress high-speed downlink signals, which may support data rates of up to 10 gigabits per second or 12.5 gigabits per second. For example, the high-speed receiver  442  may in turn pass received data (e.g., image data or other sensor data) to the system-on-a-chip  432  via a serial bus interface (e.g., a Peripheral Component Interconnect Express (PCIe) Gen 4 bus). 
     The system  400  includes a low-speed transmitter  444  with an output terminal  466  coupled to a fifth node  456 . For example, the low-speed transmitter  444  may generate signals at the output terminal  466  using Low-Voltage Complementary Metal Oxide Semiconductor (LVCMOS). For example, the high-speed receiver  442  may be configured to operate at a higher carrier frequency than the low-speed transmitter  444 . In some implementations, the low-speed transmitter  444  is configured to transmit CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for the sensor device  402  connected via the coaxial cable  410 . For example, the low-speed transmitter  444  may read data (e.g., control data, firmware, or triggering data) for transmission from the system-on-a-chip  432  via a serial bus interface (e.g., a Peripheral Component Interconnect Express (PCIe) Gen 4 bus). 
     The system  400  includes a low-speed receiver  446  with an input terminal  482  coupled to a sixth node  476 . The system includes an amplifier  480  (e.g., including an operational amplifier) coupling the sixth node  476  to the input terminal  482 . For example, the low-speed receiver  446  may receive signals at the input terminal  482  using Stub Series Terminated Logic (SSTL). In some implementations, the low-speed receiver  446  is configured to receive CoaXPress low-speed uplink signals, which may support data rates of 42 megabits per second. For example, the uplink can be used for sensor (e.g., camera) control, triggering and firmware updates for the sensor device  402 . For example, the low-speed receiver  446  may in turn pass received data (e.g., control data, firmware, or triggering data) to the sensor  430  via a native interface (e.g., an LVDS/Mobile Industry Processor Interface (MIPI)/display port (DP) interface). 
     For example, the high-speed transmitter  440  and the high-speed receiver  442  may be configured to operate at a higher carrier frequency than the low-speed transmitter  444  and the low-speed receiver  446 . In some implementations, the high-speed transmitter  440  and the high-speed receiver  442  are configured to transfer CoaXPress high-speed downlink signals and the low-speed transmitter  444  and the low-speed receiver  446  are configured to transmit CoaXPress low-speed uplink signals. 
     The system  400  includes a low-speed injection circuitry that couples the output terminal  466  of the low-speed transmitter  444  to the first node  452  and the second node  454  to enable the transmission of low-speed signals over the coaxial cable  410  concurrent with reception of high-speed signals by the high-speed receiver  442  and supply of power by the power-over-coax direct current injector  420 . The low-speed injection circuitry includes a first inductor  450  connected between the first node  452  and the fifth node  456 , a second inductor  451  connected between the second node  454  and the fifth node  456 , and a first resistor  453  connected between the fifth node  456  and a ground node. The low-speed injection circuitry also includes a third capacitor  455  connected between the fifth node  456  and a ground node. In some implementations, the electrical parameters of the low-speed injection circuitry may be chosen to correct or mitigate baseline wander caused primarily by the power-over-coax direct current injector  420  and/or its passives  426 . For example, the first inductor  450  and the second inductor  451  may be 700 nanohenry inductors. For example, the first resistor  453  may be a 4 Ohm resistor. For example, the third capacitor  455  may be a 100 picofarad capacitor. The electrical parameters of the low-speed injection circuitry may result in a sufficiently long RL time constant (e.g., 1200 nanoseconds) to mitigate signal integrity degradation of the low-speed signals by baseline wander. 
     The system  400  includes a high-pass filter coupling the first differential input terminal  462  to the first node  452  and coupling the second differential input terminal  464  to the second node  454 . The high-pass filter includes a first capacitor  460  connected between the first differential input terminal  462  and the first node  452 ; and a second capacitor  461  connected between the second differential input terminal  464  and the second node  454 . For example, the first capacitor  460  and the second capacitor  461  may be 33 picofarad capacitors. Asymmetry between the differential pair may generate low-speed noise at high-speed receiver  442 , which may propagate from the low-speed transmitter  444  to the high-speed receiver  442 . For example, asymmetry may be caused by “Cable vs 50 ohm” impedance mismatch, the passives  426 , and/or component tolerances in the circuitry of the compute device  404 . The high-pass filter may filter out this low-speed noise coupling, resulting in better high-speed signal integrity. 
     The system  400  includes a low-speed extraction circuitry that couples signals from the third node  472  to the sixth node  476 . The low-speed extraction circuitry includes a third inductor  470  and a second resistor  471  connected in series between the third node  472  and the sixth node  476 . For example, the third inductor  470  may be a 900 nanohenry inductor. For example, the second resistor  471  may be a 280 Ohm resistor. The low-speed extraction circuitry may have an unbalanced structure, which may provide better low-speed signal integrity than balanced topologies. In some implementations, the fourth node  474  is isolated from the sixth node  476 . 
       FIG.  5    is a graph  500  of examples of low-speed voltage signals with different levels of baseline wander distortion. The y-axis of the graph  500  represents voltage and the x-axis represents time. The graph  500  overlays plots of two examples of low-speed voltage signals from different power-over-coax systems. A first low-speed voltage signal  510  is from a power-over-coax system subject to significant baseline wander distortion, which causes the voltage levels to exponentially decay toward a mean value between state transitions of the first low-speed voltage signal  510 . This baseline wander distortion may cause signal integrity degradation. For example, the baseline wander distortion may cause voltage level decay with an RL time constant, which may be approximately proportional to L_PoCx/Req (where L_PoCx is an inductance of a power-over-coax injector and its associated passives and Req is an equivalent resistance of a circuit coupling a low-speed transmitter to a coaxial cable). Although, not depicted in the graph  500 , this baseline wander distortion can be particularly significant during long strings of the same symbol (e.g., long stings of ones or long strings of zeros) in the first low-speed voltage signal  510 . 
     The graph  500  also shows a plot of a second low-speed voltage signal  520  from a power-over-coax system with baseline wander correction to mitigate baseline wander distortion. For example, the low-speed injection circuitry  240  of  FIG.  2    may be utilized to implement baseline wander correction and generate the second low-speed voltage signal  520 . The resulting system may have a lower equivalent resistance (Req), which may increase the RL time constant and mitigate the baseline wander distortion in the system. The difference  530  between the second low-speed voltage signal  520  and the first low-speed voltage signal  510  depicted in the graph  500  represents a signal integrity advantage of this later power-over-coax system that generates the second low-speed voltage signal  520 . 
       FIG.  6    is a circuit diagram of an example of a system  600  including passives for connecting a power-over-coax power source to a coaxial cable with drawings of example components. The system  600  includes a coaxial cable connector with a first conductor  602  coupled to the first node  604 . In this example, the first conductor  602  is connected to the first node  604 . For example, when connected to a coaxial cable, the first conductor  602  may be connected to an inner conductor of the coaxial cable. For example, the coaxial cable connector may be an HFM connector, or any coaxial cable connector that is impedance matched to the coaxial cable to be used. The system  600  includes a power-over-coax direct current injector  610  coupled to the first node  604 . The power-over-coax direct current injector  610  may supply current (e.g.,  2 A direct current) that may flow through a coaxial cable connected to the coaxial cable connector to a sensor device (e.g., the sensor device  102 ) that is powered by this supplied current. The power-over-coax direct current injector  610  is coupled to the first node  604  via three inductors connected in series, including a first inductor  620 , a second inductor  622 , and a third inductor  624 . 
     For example, the first inductor  620 , the second inductor  622 , and the third inductor  624  may be configured to support power-over-coax systems delivering 2 Amps of direct current power via a coaxial cable (e.g., 2 A @ 125 C (64 W@35V)). This may help to support higher end sensors (e.g., radar or lidar sensors). The first inductor  620  is a 1 microhenry inductor. The first inductor  620  is in a component package with dimensions 7.19 mm×2.54 mm×4.5 mm. The first inductor  620  may have a larger spacing between windings than conventional 1 microhenry inductors, which may reduce capacitance of the first inductor  620 . These properties of the first inductor  620  may be important to maintain high-speed signal integrity. The second inductor  622  is a 2.2 microhenry inductor. The second inductor  622  is in a component package with dimensions 5.87 mm×4.98 mm×3.81 mm. The third inductor  624  is a 4.7 microhenry inductor. The third inductor  624  is in a component package with dimensions 5.6 mm×5.6 mm×2.85 mm. For example, the first inductor  620 , the second inductor  622 , and the third inductor  624  may be used as the passives  126  of  FIG.  1   . For example, the first inductor  620 , the second inductor  622 , and the third inductor  624  may replace the power inductor  212  of  FIG.  2   . For example, the first inductor  620 , the second inductor  622 , and the third inductor  624  may be used as the passives  426  of  FIG.  4   . 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to improve a user experience and provide convenience. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to better design future products by arranging components including sensor devices and compute devices to optimize performance in larger system. Thus, the use of some limited personal information may enhance a user experience. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of vehicle networks, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In another example, users can select not to provide sensor throughput and/or sample loss data. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, sensor data collection statistics can be determined by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as averages of past data, other non-personal information available to vehicle computing services, or publicly available information. 
     While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures.