Nortel Networks 411-2021-111 manual Modulation, Omni, Dqpsk, Return loss, Reverse path

xivList of terms

Modulation

The process of placing information on an RF carrier. The modulation technique may involve changing the amplitude, frequency, or phase of the carrier determined by the modulation index.

NES

Non-expanded Spectrum. The frequency spectrum initially assigned to the cellular band. The Non-expanded Spectrum provides 333 channels to each of the two bands, the A-Band and the B-Band.

Omni

An antenna design which permits radiation in essentially all H-Plane azimuths. In cell sites, an Omni configuration means a single set of omni antennas is used for all channels.

π/4 DQPSK

Variation of Differential Quadrature Phase Shift Keying used in D_AMPS IS-54 TDMA for improved spectral characteristics and phase resolution. Permissible phase changes are integral multiples of π/4 radians (45 degrees). π/4 is used to reduce the peak to root mean square ratio requirements for linear PAs.

Return loss

A logarithmic relationship of the incident signal to the reflected signal as expressed, in dB, by the following relationship:

Return Loss = 10 log Pr

Pi

where Pi = incident power in watts Pr = reflected power in watts

The strength of the signal, expressed in dB, reflected by a load back into a transmission line due to impedance mismatch. -14 dB corresponds to a VSWR of 1.5:1.

Reverse path

The path from cellular subscriber terminal to cell site.

RF

Radio Frequency. Electromagnetic energy of the frequency range just above the audible frequencies and extending to visible light.

RIP

Rack Interface Panel. The RIP is the interface between the cell site power supply and the cell site equipment.

411-2021-111 Standard 01.01 June 1996