Method of processing a digital signal derived from an analog input signal of a gnss receiver, a gnss receiver base band circuit for carrying out the method and a gnss receiver

A GNSS receiver baseband circuit for processing a raw digital signal which is restricted to a fixed raw signal frequency band, the receiver base band circuit comprising:

• an analyzing unit configured to analyze the raw digital signal to identify a plurality of interferer frequencies, each associated with a respective interferer, within the raw signal frequency band;
• a band stop unit configured to filter the raw digital signal, the band stop unit including a plurality of separate band stop subunits connected in series, each of the plurality of band stop subunits being configured to suppress a respective interferer and including:
• a single mixer;
• a single numerically controlled oscillator;
• and
• a single band stop filter, wherein the single numerically controlled oscillator is configured to control the single mixer, and the single band stop filter is coupled to the single mixer and configured to suppress the respective interferer within a suppression band containing a fixed suppression frequency, and wherein:
• a first one of the plurality of band stop subunits is configured to shift the raw digital signal from the raw signal frequency band by a difference between the fixed suppression frequency and a first interferer frequency before the suppression of the respective interferer, within the respective suppression band of the band stop unit,
• each of the plurality of band stop subunits following the first band stop subunit is configured, in response to a phase signal from the preceding band stop subunit and an interferer frequency associated with the respective interferer suppressed by the respective band stop subunit, to further shift the shifted digital signal before the suppression of the respective interferer, within the suppression band of the respective band stop unit, and
• the band stop unit includes a further mixer that is configured to further shift the shifted digital signal to a fixed filtered frequency band for providing a filtered digital signal restricted to the filtered frequency band after suppression of a last interferer.

A GNSS receiver baseband circuit for processing a raw complex digital signal which is restricted to a fixed raw signal frequency band, comprising:

• an analyzing unit configured to analyze the raw complex digital signal to identify any continuous wave interferers within the raw signal frequency band;
• a band stop unit configured to filter the raw digital signal, the band stop unit including a plurality of band stop subunits as separate band stop subunits connected in series, each of the plurality of band stop subunits being configured to suppress a single continuous wave interferer identified by the analyzing unit and including:
• a single complex mixer;
• a single numerically controlled oscillator;
• and
• a single band stop filter,
• wherein the single numerically controlled oscillator of each band stop subunit is configured to control the single complex mixer, and the single band stop filter is coupled to the single complex mixer and configured to suppress a respective interferer within a suppression band containing a fixed suppression frequency, wherein:
• a first one of the plurality of band stop subunits is configured to shift, without a shift through DC, the raw complex digital signal from the raw signal frequency band by a difference between a fixed suppression frequency and a first interferer frequency of a first identified continuous wave interferer, by multiplying, in the complex mixer, the raw complex digital signal with a complex exponential signal derived by the associated numerically controlled oscillator from a phase signal corresponding to the first interferer frequency and suppress the suppression band of the band stop filter,
• a second one of the band stop subunits is configured to further shift the shifted complex digital signal by a difference between a second interferer frequency and the first interferer frequency by multiplying, in the complex mixer, the shifted complex digital signal with a complex exponential signal derived by the associated numerically controlled oscillator from a difference between a phase signal corresponding to the second interferer frequency and the phase signal corresponding to the first interferer frequency and suppress the suppression band of the band stop unit, and
• the band stop unit further includes a further complex mixer configured to shift the further shifted complex digital signal to a fixed filtered frequency band for providing a filtered complex digital signal restricted to the fixed filtered frequency band after suppression of a last identified continuous wave interferer.

A GNSS receiver baseband circuit for processing a raw digital signal which is restricted to a fixed raw signal frequency band, comprising:

• an analyzing unit configured to analyze the raw digital signal to identify interferer frequencies within the raw signal frequency band;
• a band stop unit configured to filter the raw digital signal, the band stop unit including a plurality of band stop subunits as separate band stop subunits connected in series, each of the plurality of band stop subunits being configured to suppress a respective interferer identified by the analyzing unit and including:
• a first band stop subunit including:
• a first single numerically controlled oscillator controlled by a first interferer frequency identified by the analyzing unit, and outputting a first complex signal based on the first interferer frequency;
• a first single mixer controlled by the first complex signal output by the first single numerically controlled oscillator and configured to multiply the raw digital signal with the first complex signal and to thereby shift in frequency, without a shift through DC, the raw digital signal from the raw signal frequency band by a difference between a fixed suppression frequency and the first interferer frequency;
• and
• a first single band stop filter coupled to the first single mixer and configured to suppress a shifted first interferer within a suppression band, wherein the shifted first interferer corresponds to a first respective interferer identified by the analyzing unit;
• and
• a second band stop subunit including:
• a second single numerically controlled oscillator controlled by a first phase signal corresponding to the first interferer frequency and controlled by a second interferer frequency identified by the analyzing unit, and outputting a second complex signal based on a phase difference between the second interferer frequency and the first interferer frequency;
• a second single mixer controlled by the second complex signal output by the second single numerically controlled oscillator and configured to multiply the shifted raw digital signal with the second complex signal and to thereby further shift in frequency, without a shift through DC, the shifted raw digital signal by a difference between the second interferer frequency and the first interferer frequency;
• and
• a second single band stop filter coupled to the second single mixer and configured to suppress a shifted second interferer within a suppression band, wherein the shifted second interferer corresponds to a second respective interferer identified by the analyzing unit;
• and
• a further mixer configured to further shift the further shifted digital signal to a fixed filtered frequency band for providing a filtered digital signal restricted to the filtered frequency band after suppression of a last interferer.