1. FAKRA Connector Introduction
FAKRA (Fachkreis Automobil, a german standard) connectors are SMB based automotive-grade connectors that can operate up to 6 GHz. These connectors are embedded within a plastic housing with a locking feature that has an audible clicking noise which lets you know a connection has been made. They are available in 14 different mechanical layouts which are color coded for easy identification and mis-matching prevention.
Orbbec Gemini 335Lg is equipped with FAKRA-Z connector.
Figure 1-1 Different FAKRA Connectors
2. Recommended Cable
The Gemini 335Lg camera utilizes ADI’s GMSL2 technology, a cost-effective, simple, and scalable SerDes solution. Fakra cables, which connect the Serializer and Deserializer, have a significant impact on the performance of the GMSL2 channel. Different cables have various characteristics and are suited for different applications.
For example, lightweight and flexible cables with a small bending radius usually have thinner wire cores, which require less copper and are relatively low-cost. However, their insertion loss and return loss characteristics are not the best, making them suitable for short-distance applications where the equipment is not fixed and may require frequent bending. On the other hand, cables with thicker wire cores have better insertion and return loss characteristics, making them ideal for long-distance transmission and fixed installations where the equipment doesn’t need to be moved. However, the thicker wire cores also come with higher costs. Regardless of the cable type chosen, it must meet ADI’s GMSL2 channel specifications.
The serializer chip used in Gemini 335Lg camera is the MAX9295D, which supports both coaxial and twisted-pair transmission. Since the module also utilizes POC (Power over Coax) technology, the external Fakra connection cable must be coaxial. Below is a table listing the key parameters for selecting Fakra cables, based on ADI’s GMSL2 technical documentation.
Table 2-1 Cable specifications
| Category | Recommend Spec. | Notes |
| Cable type | Coaxial cable |  |
| Transmission frequency range | 0 ~ 6GHz | |
| Characteristic impedance | 50Ω ± 2Ω | Reconmended |
| Rated current | ≥ 1A | Typical POC voltage: 12V；Ripple: ≤ ±10% |
| DC resistance | ＜ 0.1Ω/m | |
| Insulation withstanding voltage | ≥ 500V AC | |
| Insulation resistance | ≥ 100MΩ | |
| Contact resistance | ≤ 5mΩ (Initial) | |
| Cable length | The maximum length
of commonly used cables are listed as follows: RG174：≤5m Dacar 302/RG58：≤15m |
According to ADI’s MAX9295D datasheet, “Cables with an attenuation of 1.1dB/m can support up to a maximum length of 15m (3.2mmφ, 6Gbps, 105℃).”
Detailed information is in page 1. |
| Bend radius | RG174:
Static 3x cable OD；Dynamic 10x cable OD Dacar 302： Static 5x cable OD；Dynamic 15x cable OD |
OD: Out Diameter |
| Insertion loss (IL) | −17dB MAX @ 3GHz
(6Gbps / 187.5Mbps) |
Information is according to “GMSL2 Channel Specification User Guide Rev 1“. Detailed information is in page 16. |
| Return loss (RL) |  |
|
| Tensile strength | ≥ 110N | |
| Ingress protection | IP67 (recommended) | |
| Ambient temperature | -40 ~ 105℃ | |
| Recommended cable and connector manufacturers | Cable: Amphenol RF, Belden wire & cable, TE Connectivity, HUBER + SUHNER, Lenoi, etc.
Connector: Rosenberger, Molex, TE Connectivity, Amphenol RF, etc. |
|
| Recommended cables | Amphenol RF: https://www.mouser.com/ProductDetail/Amphenol-RF/095FJZFJZSHM500?qs=zW32dvEIR3sjRLgtRmvHeA%3D%3D
Allied Vision, Inc. |
https://www.mouser.com/datasheet/2/18/2/ |
3. Orbbec Default Cable Drawins
i.ORBBEC Box-packed Gemini 335Lg Deafult Cable Drawing
ii. Orbbec Gemini 335Lg FAKRA Connector Drawing
