Agilent expands 86100D digital communications analyzer singlemode, multimode receiver bandwidth

Agilent Technologies Inc. (NYSE:A) has enhanced the ability of the Agilent 86100D digital communications analyzer (DCA) to perform optical transmitter compliance testing. Leveraging a new approach called system impulse response correction (SIRC), the instrument can now accommodate multimode optical receivers with bandwidths in excess of 25 GHz and singlemode receivers with near 100-GHz bandwidths.

In addition to improving test accuracy for optical compliance testing in design and manufacturing applications where data rates don’t exceed 10 Gbps, the improvement positions the DCA as a tool that can help in next-generation 26-Gbps applications. As previously reported, technicians have already begun work on optical transmitters and receivers for 25-Gbps transmission over multimode fiber (see “VCSEL-based 25-Gbps transmission at 850 nm nearing readiness”). However, the large physical size of multimode-compatible photodetectors has prevented optical oscilloscope channels to provide the bandwidth necessary for accurate waveform analysis, Agilent asserts.

The new SIRC approach increases the measurement bandwidth of the 86105D from 20 GHz to more than 25 GHz, Agilent says. SIRC also enables the 86105D to be configured as a multimode reference receiver for standards-based compliance testing at both 25 and 28 Gbps. The 86115D also can provide what Agilent touts as the industry’s only quad-port reference receiver for 4x25-Gbps 100-Gigabit Ethernet test.

Agilent notes that while the frequency responses of optical reference receivers are usually defined within standards, some deviation from an ideal frequency response is typically allowed to enable their production at a reasonable cost. However, these deviations can cause variation in measurement results among test systems. By performing an impulse-response analysis, Agilent says its oscilloscope channel’s frequency response is precisely determined. This ability enables the 86100D DCA to correct frequency response deviations and provide waveform results as if the reference receiver were ideal.

Using the SIRC calibration, the 86100D mainframe also can make real-time corrections to the raw waveforms, Agilent adds. The displayed signal thus appears as if it had been acquired with a system that has an ideal frequency response. In fact, the SIRC process can help create an ideal reference receiver for virtually any data rate within the physical limits of the system, Agilent asserts. Users also can increase or decrease the effective bandwidth of the measurement system by approximately 50 percent from the nominal hardware capabilities.

The Agilent 86100 SIRC process accurately preserves random signal components such as jitter and noise. General signal processing techniques can incorrectly filter these signal components resulting in an incorrect waveform display, Agilent concludes.

The Agilent 86100 family of optical receivers -- which includes the 86105C, 86105D, 86115D, and 86116C -- can be ordered with a special SIRC option. The option is available on July 1, with solution prices starting at $6,000. Current users of these modules can upgrade their instruments with the SIRC capability at Agilent service centers.

SIRC capability is also available with the 86100C DCA-J when configured with the N1010A Flex-DCA software.