Abstract: A transmitter for a radio transmission system has an encoder for encoding data according to an error correction code and supplying a digital output stream of bits which are then distributed over a selectable number of carriers belonging to a group of carriers that are uniformly distributed over a transmission channel, so as to constitute a frequency division multiplex. Then the stream is subjected to time interleaving responsive to a distribution given by the bit spreading module which achieves distribution and frequency interleaving operating on the carriers; the stream is then modulated in phase or possibly a phase and amplitude.

Abstract: To carry out tests on a mobile telephony network, a two-band mobile telephone is used. This mobile telephone is improved by a parametrizing device by which the mobile telephone declares itself to the network either as a single-band telephone in a first frequency band, or as a single-band telephone is a second frequency band, or as a two-band telephone in both these frequency bands. The network then exploits the mobile telephone in the mode corresponding to its declaration. It is possible with only one instrument, to measure all the transmission characteristics of the network.