A radar signal processing circuit mounted on an aircraft comprising: a digital processing section, wherein for each of a left radar channel, a right radar channel, and an ambiguous radar channel, the digital processing section includes: a radar gate correlation circuit configured to sample radar return data at a sampling rate; a correlation band pass filter configured to stretch the sampled radar return data to a continuous wave signal; a mixer configured to down sample an in-phase component and a quadrature component of the CW signal to a Doppler frequency; a band pass filter centered on the Doppler frequency; a phase processor configured to receive processed radar return data from said digital processing section, said phase processor further configured to determine a phase difference between radar return data from an ambiguous channel and a left channel, and a phase difference between radar return data from the right channel and the left channel; and characterised by said phase processor being further configured to determine a phase difference between radar return data from a right channel and the ambiguous channel; and further characterised by a processing unit configured to receive the three phase differences, adjust a phase bias (570, 572, 574) for the three phase differences, resolve phase ambiguities between the three phase differences to provide a signal, and filtering the signal to provide a physical angle to a target in aircraft body coordinates, wherein said processing unit is configured to resolve phase ambiguities by determining a plurality of physical angle solutions for each received phase difference based on the separation between antennas associated with the different channels and the wavelength of the radar signal, wherein roughly equivalent physical angle solutions for the different received phase differences are identified as the unambiguous physical angle solution. a digital processing section, wherein for each of a left radar channel, a right radar channel, and an ambiguous radar channel, the digital processing section includes: a radar gate correlation circuit configured to sample radar return data at a sampling rate; a correlation band pass filter configured to stretch the sampled radar return data to a continuous wave signal; a mixer configured to down sample an in-phase component and a quadrature component of the CW signal to a Doppler frequency; a band pass filter centered on the Doppler frequency; a phase processor configured to receive processed radar return data from said digital processing section, said phase processor further configured to determine a phase difference between radar return data from an ambiguous channel and a left channel, and a phase difference between radar return data from the right channel and the left channel; and a radar gate correlation circuit configured to sample radar return data at a sampling rate; a correlation band pass filter configured to stretch the sampled radar return data to a continuous wave signal; a mixer configured to down sample an in-phase component and a quadrature component of the CW signal to a Doppler frequency; a band pass filter centered on the Doppler frequency; characterised by said phase processor being further configured to determine a phase difference between radar return data from a right channel and the ambiguous channel; and further characterised by a processing unit configured to receive the three phase differences, adjust a phase bias (570, 572, 574) for the three phase differences, resolve phase ambiguities between the three phase differences to provide a signal, and filtering the signal to provide a physical angle to a target in aircraft body coordinates, wherein said processing unit is configured to resolve phase ambiguities by determining a plurality of physical angle solutions for each received phase difference based on the separation between antennas associated with the different channels and the wavelength of the radar signal, wherein roughly equivalent physical angle solutions for the different received phase differences are identified as the unambiguous physical angle solution.