Abstract: A transmit circuit reduces undesired amplitude modulation (AM) in transmit signal pulses by substituting predetermined amplitude information for actual pulse amplitude information during portions of the pulse corresponding to nominally constant amplitudes. For example, GMSK and certain other modulation formats use a desired transmit pulse shape that includes a nominally flat middle portion. An exemplary AM reduction circuit detects generated pulse values corresponding to the nominally constant-amplitude portions of the transmit pulse and substitutes predetermined, preferably constant, amplitude values in their place. As such, the circuit may include a comparator used to detect the pulse values corresponding to variable amplitude portions of the pulse, which it passes through, and to detect those amplitude values corresponding to constant-amplitude portions of the pulse, which it replaces with substituted values. Such operation may include amplitude value filtering, and such operations may be modal, e.g.

Abstract: An air frame synchronisation signal is transmitted as a data signal over a PCM link from a central unit to a plurality of remote radio transceivers, allowing the remote radio transceivers to recreate the AFS signal with the desired accuracy, compensating for transmission delays.