Dual-mode radio receiver for receiving narrowband and wideband signals

A radio receiver having a wideband mode for receiving radio signals containing wideband signals and a narrowband mode for receiving radio signals containing narrowband signals, comprising:

• a. a downconverter for downconverting the radio signals to generate downconverted signals;
• b. wideband filter means for filtering the downconverted signals with a wide filter bandwidth adapted to the wideband signals and generating filtered signals containing the wideband signals or narrowband signals;
• c. a wideband demodulator for receiving the filtered signals containing wideband signals and demodulating the wideband signals contained in the filtered signals;
• d. a digitizer for digitizing the filtered signals containing the narrowband signals and generating digital signals;
• e. first frequency-shifting means for shifting the digital signals so as to shift first narrowband signals at a first radio channel frequency to a desired center frequency and generate first frequency-shifted signals;
• f. narrowband filter means for filtering the first frequency-shifted signals with a filter bandwidth adapted to the first narrowband signals so as to extract the first narrowband signals;
• and
• g. a narrowband demodulator for demodulating the extracted first narrowband signals to generate first demodulated signals.

A method for receiving radio signals with a radio receiver where the radio signals contain first narrowband signals at a first radio channel frequency and second narrowband signals at a second radio channel frequency, comprising:

• a. downconverting the radio signals to generate downconverted signals;
• b. filtering the downconverted signals with a wide filter bandwidth to generate filtered signals, wherein the filtered signals have a first subband containing the first narrowband signals and a second subband containing the second narrowband signals;
• c. digitizing the filtered signals to generate digital signals, wherein the digital signals represent the radio signals in polar form and include phase signals and amplitude signals;
• d. frequency shifting the digital signals so as to shift the first narrowband signals by adding a first phase slope to the phase signals to a predetermined center frequency and generate first frequency-shifted signals;
• e. frequency shifting the digital signals so as to shift the second narrowband signals by adding a second phase slope to the phase signals to the predetermined center frequency and generate second frequency-shifted signals,
• f. filtering the frequency-shifted signals with a filter bandwidth adapted to the narrowband signals so as to extract the first and second narrowband signals;
• and
• g. demodulating the extracted first and second narrowband signals to generate demodulated signals.

A method for receiving radio signals with a radio receiver where the radio signals contain alternatively wideband signals or narrowband signals, comprising:

• a. downconverting the radio signals to generate downconverted signals;
• b. filtering the downconverted signals with a wide filter bandwidth adapted to the wideband signals to generate filtered signals alternatively containing the wideband signals or narrowband signals;
• c. demodulating the filtered signals containing wideband signals and demodulating the wideband signals contained in the filtered signals;
• d. digitizing the filtered signals containing the narrowband signals to generate digital signals;
• e. frequency shifting the digital signals so as to shift first narrowband signals at a first radio channel frequency to a predetermined center frequency and generate first frequency-shifted signals;
• f. filtering the first frequency-shifted signals with a filter bandwidth adapted to the first narrowband signals so as to extract the first narrowband signals;
• and
• g. demodulating the extracted first narrowband signals to generate first demodulated signals.

A radio communication system for communicating with radios alternatively by wideband signals and narrowband signals, comprising:

• a. a first narrowband transceiver for transmitting first narrowband signals;
• b. a second narrowband transceiver for transmitting second narrowband signals;
• c. a wideband transceiver for transmitting wideband signals;
• and
• d. a radio including a radio receiver having a wideband mode for receiving radio signals containing wideband signals and a narrowband mode for receiving radio signals containing narrowband signals, the radio receiver including:
• i) a downconverter for downconverting the radio signals to generate downconverted signals;
• ii) wideband filter means for filtering the downconverted signals with a wide filter bandwidth adapted to the wideband signals and generating filtered signals containing the wideband signals or narrowband signals, wherein the filtered signals containing the narrowband signals have a first subband containing the first narrowband signals and a second subband containing the second narrowband signals;
• iii) a wideband demodulator means for receiving the filtered signals containing wideband signals and demodulating the wideband signals contained in the filtered signals;
• iv) a digitizer for digitizing the filtered signals containing the narrowband signals and generating digital signals;
• v) first frequency-shifting means for shifting the digital signals so as to shift the first narrowband signals to a predetermined center frequency and generate first frequency-shifted signals;
• vi) second frequency-shifting means for shifting the digital signals so as to shift the second narrowband signals to the predetermined center frequency and generate second frequency-shifted signals,
• vii) narrowband filter means for filtering the frequency-shifted signals with a filter bandwidth adapted to the narrowband signals so as to extract the first and second narrowband signals;
• and
• viii) a narrowband demodulator means for demodulating the extracted first and second narrowband signals and generating demodulated signals.