Tag Archives PAM-4

We at VIAVI have long been aware of the impact of latency on the datacoms and telecoms ecosystem.  Specialized applications have been developed which allow customers to develop and evaluate ICs, optical modules, ASICs and systems based on their bandwidth throughput and latency. Historically, people have focused on microseconds, but increasingly – especially driven by […]

Modern high-speed links for the fastest Ethernet rates of 400GbE and above use PAM-4 electrical modulation. This modulation format allows interfaces to run at the speeds required for 400GbE and above, but PAM-4 modulation is more susceptible to the impacts of noise and signal integrity.  This is mitigated by the use of forward error correction […]

While evaluating high-speed network test equipment, it may be tempting to forgo deep physical layer testing capabilities to save money and reduce testing complexities. In some cases, these ‘just good enough’ solutions appear to fit the bill, but lack of deep insights can lead to product re-designs, longer development cycles or systemic failures in the […]

Since the emergence of 400 Gigabit Ethernet (GbE) around 5 years ago, we have seen PAM-4 modulation replace NRZ on both optical and electrical interfaces. We now see a broad and healthy ecosystem building for 400 GbE, and even 800 GbE, using PAM-4 signaling.  In fact, we are even seeing the first 100 Gb per […]

One of the most significant areas we have seen driving new test and measurement requirements has been data center interconnect – DCI. This rapidly growing area leverages the emergence of pluggable coherent optics (DCO) to allow rapid scaling of data center interconnect bandwidth based on an open, multi-vendor ecosystem. For the DCI market to grow […]

400G optics have already presented tremendous R&D challenges during the first phases of 400G QSFP-DD development. PAM-4 high speed signalling in both the optical and electrical domains, debugging module firmware and the interaction with the DSP firmware are clear examples, not to mention the new challenge brought about by the latest emerging standard in optical […]

 This is a re-post of an article in Gazettabyte, © Roy Rubenstein 2017 The race is on to deliver 400-gigabit optical interfaces in time for the next-generation of data centre switches expected in late 2018. The industry largely agrees that a four-wavelength 400-gigabit optical interface is most desirable yet alternative designs are also being developed. Optical […]

In this Olympic year, the motto Citius, Altius, Fortius (Latin for Faster, Higher, Stronger) seems very relevant to where we are with Ethernet networking. We need faster bandwidth, higher levels of service and stronger performance to push around all those videos of cats—as well as the more serious (and less cute) business traffic. Approximately every […]

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