HP TM 11-6625-2779-14&P manual Section General Information Introduction

Model 3555B Section I

SECTION I

GENERAL INFORMATION

1-1. INTRODUCTION.

1-2. The Hewlett-Packard Model 3555 B Transmission and Noise Measuring Set is a versatile set designed for uses in testing telecommunications equipment. The extreme sensitivity of this set, linked with its wide and flat frequency response, make it suitable for noise and level measurements at voice, program and carrier frequencies. Levels from -80dBm to +30dBm (10dBm to +120dBm) full-scale can be measured and displayed on a meter calibrated to indicate both in dBm for level measurements and in dBm for noise measurements.

1-3. The set combines the features of a voice and noise frequency measuring set and the features of a carrier frequency measuring set. For voice and program frequencies impedances of 900 ohms and 600 ohms are

provided, balanced or unbalanced, bridged or terminated. For noise measurements a noise-to-ground (Ng) function is provided which provides 40dB of

attenuation for longitudinal noise. For carrier frequencies 600 ohm, 135 ohm and 75 ohm impedances are provided. The 600 and 135 function can be either balanced or unbalanced, bridged or terminated; The 75 function is unbalanced only. Bridging impedance is over 100 kilohms, allowing measurements with a bridging loss of less than 0.05dB. The meter indicates in dBm for any selected input impedance.

1-4. The 3555B includes a 3kHz flat, a C-Message, a Program and a 15kHz flat filter, each easily selectable by a front panel control. These filters conform to the standards set up .by the Bell System and Edison Electric Institute. Other filters are available upon request.

Figure 1-1. Model 3555B Transmission and Noise Measuring Set

1-1