Agilent/Keysight 4925B

The Agilent/Keysight 4925B is a portable Bit Error Rate Test Set engineered for data communications system validation across RS-232-C/V.24 and V.35 interfaces. It executes bit and block error tests, errored seconds analysis, error-free second percentages, timing delay measurement, and parity error detection in both asynchronous and synchronous configurations. Asynchronous testing spans 75 b/s to 19.2 kb/s in framed or unframed modes.

Synchronous operation supports data rates to 72 kb/s with internal clock generation, enabling Digital Data System (DDS) testing. The instrument transmits FOX messages encoded in 5-bit Baudot, 6-bit EBCD, 7-bit ASCII, or 8-bit EBCDIC for terminal and printer validation.

Technical Specifications

• Asynchronous data rates: 75 b/s to 19.2 kb/s (framed/unframed)


• Synchronous data rates: Up to 72 kb/s with integrated clock


• Error measurements: Bit error rate, block error rate, errored seconds, percent error-free seconds, timing delay, parity errors


• Diagnostic capabilities: Dropout detection, clock slip detection, RTS-CTS delay measurement


• Protocol support: FOX message transmission (Baudot, EBCD, ASCII, EBCDIC)


• Power: Six 9-volt alkaline batteries; >50 hours operation on RS-232-C/V.24


• V.35 operation requires HP 18185A or HP 18194A AC module

Key Features

• Integrated breakout box for RS-232-C/V.24 signal line manipulation and monitoring


• Cross-patching capability between DCE and DTE sides


• Multiple diagnostic startup tests: end-to-end, loopback, BELL 208B modem


• Modem fault isolation, particularly automatic equalization errors

Typical Applications DDS network characterization, modem performance validation, point-to-point serial link testing, terminal and printer connectivity verification.

Compatibility & Integration RS-232-C/V.24 and V.35 interfaces. AC power modules (HP 18185A/18194A) required for sustained V.35 operations.