The modems operate in the 900 MHz band and with a channel spacing of 25 kHz. Each
transmitted signal from a mobile is a four-level QAM signal, with an element rate of 12,000 …

The paper surveys the digital modulation methods available for use in land mobile radio
systems. The modulation methods are compared on the basis of their relative tolerances to …

Five narrowband frequency pairs in the 220-222 MHz land mobile band have been
allocated for applications in intelligent transportation systems (ITS). Low rate data …

The author presents performance evaluations for four Rake modems used to communicate
over the wideband (eg 1 MHz) HF channel. Attention is confined to performance for the …

There has been considerable activity over the past few years in the development and testing
of vehicle printers and two-way data terminals for use in law enforcement communications …

Three new general purpose wideband data facilities provide for the transmission of
synchronous and nonsynchronous, 2-level data at bit rates ranging from 19.2 to 250 kb/s …

A UHF mobile telephone system using digital modulation is described. The system uses on-
off keying of an 836-MHz carrier, the code being supplied by an adaptive delta coder with a …

The performance of a low bit rate (64 Kb/s) all digital 16-ary Differentially Encoded
Quadrature Amplitude Modulation (16-DEQAM) demodulator operating over a mobile …

Narrowband and Wideband data hybrid transmission techniques are presented and
dedicated digital radio systems are reviewed. It is shown that 1.544 Mbit/s (2.023 Mbit/s) …

Digital signalling is finding an ever-increasing number of applications in the Land Mobile
Radio Service. Mobile telephones using digital dialing signals are in widespread use, and …