Internetworking among GSM900, DCS1800 and PCS1900 systems is possible with HP 8590 E-series of portable spectrum analyzers. The new HP 85727A measurement personality together with the HP 8590 E-series analyzer provides the user with the assurance that their new multi-band systems conform to worldwide GSM standards. Complex GSM measurements are reduced to single-button operation and easy-to-use soft-key menus are labeled with familiar GMS measurement names. Results are displayed in real-time with standard GSM limit lines and masks. Key measurements that can be made by the analyzer include: phase and frequency error; demodulated data display; mean TX carrier power; power vs. time; output RF spectrum; intermodulation attenuation; spurious emissions; and combiner tuning.