Dynamic, low if, image interference avoidance receiver
First Claim
Patent Images
1. A dynamic, low IF, image interference avoidance receiver comprising:
- a programmable local oscillator for producing a local oscillator frequency;
a mixer responsive to said local oscillator frequency and an input signal frequency to provide an intermediate signal frequency which is the sum or difference between said local oscillator frequency and said input signal frequency;
a tracking programmable band pass filter responsive to said intermediate signal frequency to produce a filtered intermediate signal;
a detector responsive to said filtered intermediate signal for determining the presence of interference; and
a controller responsive to said detector determining the presence of interference for shifting both the local oscillator frequency of said programmable local oscillator and the center frequency of said tracking programmable band pass filter to maintain the intermediate signal frequency centered on the center frequency of said tracking programmable bandpass filter.
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Abstract
A dynamic low IF image interference avoidance receiver shifts the local oscillator frequency to avoid image interference and shifts the center frequency of the band pass filter to track the frequency shift of the local oscillator or uses two local oscillators, a first to shift frequency and separate the desired frequency and image interference frequency and the second to track the first and maintain the output IF at a fixed frequency
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Citations
15 Claims
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1. A dynamic, low IF, image interference avoidance receiver comprising:
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a programmable local oscillator for producing a local oscillator frequency; a mixer responsive to said local oscillator frequency and an input signal frequency to provide an intermediate signal frequency which is the sum or difference between said local oscillator frequency and said input signal frequency; a tracking programmable band pass filter responsive to said intermediate signal frequency to produce a filtered intermediate signal; a detector responsive to said filtered intermediate signal for determining the presence of interference; and a controller responsive to said detector determining the presence of interference for shifting both the local oscillator frequency of said programmable local oscillator and the center frequency of said tracking programmable band pass filter to maintain the intermediate signal frequency centered on the center frequency of said tracking programmable bandpass filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A dynamic, low IF, image interference avoidance receiver comprising:
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a first programmable local oscillator for producing a local oscillator frequency; a first mixer responsive to said local oscillator frequency and an input signal frequency to provide an intermediate signal frequency which is the sum or difference between said local oscillator frequency and said input signal frequency; a fixed low pass filter responsive to said intermediate signal frequency to produce a filtered intermediate signal frequency; a second programmable local oscillator, for producing a second local oscillator frequency; a second mixer responsive to said second local oscillator frequency and said filtered intermediate signal frequency for producing a second intermediate signal frequency which is the sum or difference between said filtered intermediate signal frequency and said second local oscillator frequency; a fixed band pass filter responsive to said second intermediate signal frequency to produce a filtered second intermediate signal; a detector responsive to said filtered second intermediate signal for detecting the presence of interference; and a controller responsive to said detector determining the presence of interference for shifting both local oscillator frequencies to maintain the second intermediate signal frequency centered on the center frequency of said fixed band pass filter. - View Dependent Claims (12, 13, 14, 15)
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Specification