Method for dynamically assigning a communication channel in a single coaxial cable between a low-noise block circuit of a parabolic antenna and at least one set-top box unit in a domestic television system, in which said low-noise block circuit is associated with a plurality of communication channels in said single coaxial cable, each of said communication channels being arranged to carry programme signals at a respective intermediate frequency, the method comprising the following operations: associating the set-top box unit and the low-noise block circuit with a respective FSK transceiver (4, 10) for transmitting and receiving messages using FSK modulation; exchanging a plurality of channel assignment messages between the set-top box unit and the low-noise block circuit, by means of respective transceivers (4, 10), in such a way that a channel identifier is automatically assigned to said set-top box for identifying one of said plurality of communication channels in said single coaxial cable for the transmission of a programme signal between said set-top box unit and said low-noise block circuit, wherein said channel identifier is dynamically associated with said set-top box unit and is associated with a sub-band of a total frequency band supported by the coaxial cable; the method further comprising the steps of: sending from the set-top box unit to the low-noise block circuit a first message representing a request for the acquisition of a channel identifier, wherein the first message includes a transmission identifier uniquely associated with the set-top box unit; sending from the low-noise block circuit to the set-top box unit a second message representing an offer of a channel identifier, wherein the second message includes the transmission identifier; wherein the low-noise block circuit starts a timer, after sending the second message; sending from the set-top box unit to the low-noise block circuit a third message representing the acceptance of said channel identifier; wherein, if the third message is not sent within a time interval determined by the timer, the channel identifier is considered to be available again, if the third message is sent within the time interval, sending, from the low-noise block circuit to the set-top box unit a fourth message of confirmation representing the correct completion of the dynamic assignment. associating the set-top box unit and the low-noise block circuit with a respective FSK transceiver (4, 10) for transmitting and receiving messages using FSK modulation; exchanging a plurality of channel assignment messages between the set-top box unit and the low-noise block circuit, by means of respective transceivers (4, 10), in such a way that a channel identifier is automatically assigned to said set-top box for identifying one of said plurality of communication channels in said single coaxial cable for the transmission of a programme signal between said set-top box unit and said low-noise block circuit, wherein said channel identifier is dynamically associated with said set-top box unit and is associated with a sub-band of a total frequency band supported by the coaxial cable; the method further comprising the steps of: sending from the set-top box unit to the low-noise block circuit a first message representing a request for the acquisition of a channel identifier, wherein the first message includes a transmission identifier uniquely associated with the set-top box unit; sending from the low-noise block circuit to the set-top box unit a second message representing an offer of a channel identifier, wherein the second message includes the transmission identifier; wherein the low-noise block circuit starts a timer, after sending the second message; sending from the set-top box unit to the low-noise block circuit a third message representing the acceptance of said channel identifier; wherein, if the third message is not sent within a time interval determined by the timer, the channel identifier is considered to be available again, if the third message is sent within the time interval, sending, from the low-noise block circuit to the set-top box unit a fourth message of confirmation representing the correct completion of the dynamic assignment. sending from the set-top box unit to the low-noise block circuit a first message representing a request for the acquisition of a channel identifier, wherein the first message includes a transmission identifier uniquely associated with the set-top box unit; sending from the low-noise block circuit to the set-top box unit a second message representing an offer of a channel identifier, wherein the second message includes the transmission identifier; wherein the low-noise block circuit starts a timer, after sending the second message; sending from the set-top box unit to the low-noise block circuit a third message representing the acceptance of said channel identifier; wherein, if the third message is not sent within a time interval determined by the timer, the channel identifier is considered to be available again, if the third message is sent within the time interval, sending, from the low-noise block circuit to the set-top box unit a fourth message of confirmation representing the correct completion of the dynamic assignment.