HSD and FAKRA are not interchangeable. HSD fits a module that specifies a 100 ohm shielded differential interface. FAKRA fits a module that specifies a 50 ohm coaxial interface for an antenna path or a coaxial high-speed data link. An automotive camera may use either connector family, depending on the serializer and deserializer architecture, port definition, cable topology, mating interface, and test method.
Start with the Electrical Interface
HSD is a fully shielded, impedance-controlled differential interconnect family. Standard HSD systems commonly use a 100 ohm signal path with shielded twisted quad cable or another differential cable structure specified by the module. HSD is a physical connector and cable system. The supported protocol, frequency, and data rate depend on the HSD variant, cable construction, assembly length, and module specification.
HSD connections may support LVDS camera links, USB, Ethernet, IEEE 1394, and other compatible low-voltage differential links. The protocol name does not replace the need to check the connector code, contact arrangement, cable structure, and electrical test requirements. For a more detailed selection process, review our HSD cable assembly guide.
FAKRA is a coded automotive coaxial interconnect family. Standard FAKRA systems commonly use a 50 ohm coaxial path with a center conductor, dielectric layer, outer conductor, and cable jacket. The interface is frequently used for radio, GNSS, cellular, WiFi, Bluetooth, V2X, and other antenna connections.
FAKRA is not limited to antenna RF. A compatible coaxial link may also carry serialized camera or sensor data when the module, connector series, coaxial cable, and complete channel support the required architecture. The connector family does not define the protocol by itself. Coding, coaxial cable compatibility, orientation, sealing, and electrical performance still need to match the module. These checks are covered in more detail in our FAKRA connector selection guide.
HSD and FAKRA Compared
The main difference between HSD and FAKRA is the electrical topology. HSD is designed around a shielded differential path. FAKRA is designed around a coaxial path referenced to the outer conductor. This difference affects the cable construction, termination, shielding transition, mating interface, and test method.
| Comparison Item | HSD | FAKRA | Selection Meaning |
|---|---|---|---|
| Electrical Topology | Shielded differential path | Coaxial path referenced to the outer conductor | Confirm the module interface before selecting the connector |
| Common Nominal Impedance | Commonly 100 ohm | Commonly 50 ohm | Connector, cable, termination, and module impedance need to match |
| Cable Structure | Shielded twisted quad or another specified differential cable | Center conductor, dielectric, outer conductor, and jacket | The cable structures require different termination methods |
| Protocol Relationship | May support LVDS, USB, Ethernet, IEEE 1394, and other specified links | May carry RF or serialized data over coax when specified | The connector family does not define the protocol |
| Frequency and Data Capability | Depends on the connector variant, cable, protocol, and assembly length | Depends on the connector series, cable, channel length, and return loss target | A universal Gbps value cannot represent either connector family |
| Shielding Focus | Conductor balance, differential impedance, crosstalk, and shield continuity | Coaxial geometry, outer conductor continuity, return loss, and insertion loss | Shielding checks need to follow the electrical topology |
| Camera Use | Used when the camera module specifies a compatible differential interface | Used when the camera module specifies a compatible coaxial interface | Camera function alone does not determine the connector |
| Telematics Use | May carry digital communication between electronic modules | Common for GNSS, cellular, WiFi, V2X, and antenna paths | One telematics unit may contain both connector families |
| Coding and Locking | Keyed and color-coded variants with locking features | Mechanical and color coding with locking features | Coding needs to match within the same connector family |
| Typical Validation | Pinout, continuity, differential impedance, TDR, eye diagram, BER, or protocol checks | Center and shield continuity, return loss, insertion loss, TDR, and link checks | The test method needs to match the signal architecture |
The connector is selected from the module interface and cable topology. A camera port defined for a 100 ohm differential path points toward HSD or another compatible differential system. A camera port designed for a coaxial SerDes path may use FAKRA or another compatible automotive coaxial interface.
Which Interface Fits the Vehicle Signal Path
| Vehicle Signal Path | Choose HSD When | Choose FAKRA When |
|---|---|---|
| Automotive Camera | The module specifies a compatible 100 ohm differential camera or data interface | The module specifies a compatible coaxial camera or SerDes interface |
| Telematics Module | The connection carries digital data between the telematics unit and another electronic module | The connection runs from the module to GNSS, cellular, WiFi, V2X, or another antenna |
| Display or Infotainment | The display link uses a compatible differential interface and pinout | The connection is a coaxial tuner, antenna, or serialized data path |
| Radio or Antenna | The module is designed around a compatible differential interface | The port is a standard 50 ohm coaxial RF path |
| Sensor or ADAS Link | The sensor output uses a compatible differential architecture | The sensor or camera output uses a compatible coaxial architecture |
A vehicle subsystem can contain both connector families. A telematics unit may use FAKRA ports for GNSS and cellular antennas while using an HSD connection for digital communication with another module. The system block diagram and module port specification provide a clearer selection basis than the subsystem name.
For antenna-side routing in telematics systems, the FAKRA code, coaxial cable, assembly length, insertion loss, connector direction, and sealing level need to match the module and antenna path. These selection points are explained in our guide to FAKRA cable assemblies for telematics modules.
Coding, Keying, and Mating Control
Both HSD and FAKRA use keyed housings and locking features to reduce mismating. A similar housing color does not make the connector families compatible. The code needs to be checked within the correct connector family and against the mating drawing.
Standard FAKRA catalogs generally define thirteen mechanical and color codes plus neutral Code Z. HSD also uses multiple coded variants. Depending on the HSD series, coding may separate interface orientation, cable exit direction, connector variants, or module ports. Color supports identification, but it does not define impedance, protocol, bandwidth, or electrical performance.
Shielding and Cable Assembly Differences
HSD performance depends on conductor geometry, pair balance, contact position, exposed conductor length, cable preparation, and the shield transition at the connector. A cable assembly may pass a basic continuity test while still producing errors at the required data rate. Differential impedance, crosstalk, and protocol margin need to be evaluated when the link specification requires them.
FAKRA performance depends on maintaining the coaxial structure through the connector transition. Center-contact position, dielectric condition, outer-conductor continuity, crimp geometry, cable deformation, and connector-to-cable impedance affect return loss and insertion loss. A stable DC connection does not confirm that the complete coaxial channel meets its frequency requirement.
FAQ
Conclusion
HSD and FAKRA need to be selected from the electrical architecture of the link. HSD fits a compatible shielded differential data path, while FAKRA fits a coaxial path that may carry antenna RF or serialized camera and sensor data. Confirm the module interface, nominal impedance, cable structure, connector coding, shielding transition, routing, and validation method before confirming the cable assembly. If the port definition or cable requirement is unclear, you can share the module drawing, cable length, connector direction, and test requirement with the Bafitop team for review.