Digital Interface Protocols


Sarokal Test Systems X-STEP™ products cover various digital interface protocols, and more protocols are constantly being implemented and explored.

See below for a list of the currently supported protocols. 

If your protocol is not on the list, please drop us a note through the contact form on the Contacts page and we'll get in touch.

10Gb Ethernet







The Ethernet standard family, the IEEE 802.3, dates back to early 1980's. Nowadays, Ethernet is getting more use modes and new protocols to convey as high-speed network computing and 4G radio base station applications are adopting 10 GbE as their backhaul technology.





Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted.

As per the OSI model, Ethernet provides services up to and including the data link layer.

Unlike previous Ethernet standards, 10 gigabit Ethernet and above only define full duplex point-to-point links which are generally connected by network switches. Shared medium CSMA/CD has not been carried over from the previous generations of Ethernet standards. Half duplex operation and hubs do not exist in 10 GbE and above.

10+ gigabit Ethernet applications include, for example, high-performance network computing & storage modules, and 4G radio base stations. 

Visit the IEEE website, 802.3 section, for more details of the Ethernet standard.

New standards are coming up to enable Base Station fronhaul traffic through Ethernet.  IEEE Project 1904 is working on this (IEEE P1904.3 - Standard for Radio Over Ethernet Encapsulations and Mappings (







The JESD204 serial interface standard was developed by JEDEC to support the increasing bandwidth needs of next-generation high-speed analog-to-digital (ADC) and digital-to-analog (DAC) data converters. 




As the sample resolution and speed of data converters keeps increasing, the interface protocol has to deal with the negative system impacts such as increased size, cost, power consumption, and layout complexity. The solution introduced by the JESD204 is Current Mode Logic (CML), which supports line bit rates similar to LVDS but with fewer pins and lower power consumption. The latest revision of the standard, JESD204B, provides a maximum line bit rate of 12.5 Gbps per lane, with support for harmonic frame clocking, alignment of multiple converter devices, and deterministic latency. 

JESD204B is becoming the dominant standard in high-speed ADC and DAC applications, including wireless transceiver architectures (e.g., GSM, WCDMA, LTE), software-defined radios (SDR), portable instrumentation, medical ultrasound equipment, plus aviation and military applications such as radar systems.

Visit for more information of the JESD204 standard.







The Common Public Radio Interface (CPRI) is an industry cooperation defining the specification for the key internal interface of radio base stations, between the Radio Equipment Control (REC) and the Radio Equipment (RE).




The CPRI specification enables flexible and efficient product differentiation for radio base stations and independent technology evolution for Radio Equipment (RE) and Radio Equipment Control (REC). The companies contributing to the CPRI Specification nowadays include Ericsson, Huawei, NEC, NSN, and Alcatel-Lucent.

CPRI allows the use of a distributed architecture where radio base stations, containing the REC, are connected to remote radio heads via lossless fibre links that carry the CPRI data. This architecture reduces costs for service providers because only the remote radio heads containing the RE need to be situated in environmentally challenging locations.

The latest CPRI Specification v6.0 defines line bit rates from 614.4 Mbps to 9.8304 Gbps (1..16X) in the traditional 8b10b coded mode and the new 10.1376 Gbps (20X) mode with the 64/66b line coding and carried by an IEEE 10 Gb Ethernet PHY.

For more information of the CPRI specification, see the CPRI website.







The Open Base Station Architecture Initiative specifies the internal interfaces of a Radio Base Station for opening the market for Base Station components and allowing distributed architecture of Base Stations.




Open Base Station Architecture Initiative was a trade association created by Hyundai, LG Electronics, Nokia, Samsung, and ZTE in September 2002 with the aim of creating an open market for cellular network base stations. An open market and modular approach for base station components would reduce the development effort and costs traditionally associated with creating base station products.

Sarokal products mainly focus on the Reference Point 3 (RP3) and RP3-01 portions of the OBSAI standard, as these two are relevant for cellular data transfer and timing synchronization between Radio Base Station components. RP3 is used in antenna and control messages between a Base Band Unit (BBU) and a Local Converter (LC). 

The RP3-01 interface realizes a high speed optical communication link between the Local Converter (LC) module and the Remote Radio Head (RRH).

The OBSAI specification defines line bit rates from 768 Mbps to 6.144 Gbps (1 to 8X modes).

Visit the OBSAI website for more information about the specification.







Your protocol was not on the list? No problem, we can implement the support for virtually any frame or packet-based protocol in our products.




The key to the affordability, flexibility, and quick turn-around times of the Sarokal test system and its protocol support is that the protocols are mostly implemented in SW, instead of custom HW with plenty of parallel logic required for high-bandwidth data processing. This is possible through smart design choices and test case optimizations, all aiming at providing the same functional testing coverage with significantly simpler HW.

Furthermore, the open-source nature of the SW architecture ensures good customizability and makes it possible to integrate customer’s own test SW and scripts into the test system.

For any questions or inquiries related to protocol support, please get in contact with us through the Contacts page.