Simplified High Frequency Tuner and Tuning Method
3 Assignments
0 Petitions
Accused Products
Abstract
A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.
99 Citations
166 Claims
-
1-36. -36. (canceled)
-
37. A tuning method comprising, with a tuning device:
-
(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing; (b) frequency translating the channel of interest to a passband that is near-baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; (c) sensing the operating temperature of the tuning device; and (d) using the sensed temperature to correct errors between the I and Q signals.
-
-
38. The method of claim 37 wherein correcting errors comprises choosing a correction factor to optimize image rejection.
-
39. The method of claim 37 wherein the passband bandwidth is about the channel spacing.
-
40. A tuning method comprising:
-
(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing; (b) frequency translating the channel of interest to a passband that is near baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; and (c) using information characterizing errors between the I and Q channels of the individual tuning device, which information has been stored within the device upon completion of device manufacture, to correct errors between the I and Q channels.
-
-
41. The method of claim 40 wherein the passband bandwidth is about a channel spacing wide.
-
42. The method of claim 40 wherein the information characterizing errors constitutes correction factors.
-
43. A method of tuning comprising:
-
(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing; (b) frequency translating the channel of interest to a passband that is near-baseband and the lower edge of which is spaced from DC by at least about the channel spacing, by mixing the channel of interest with approximately phase-quadrature local oscillator signals thereby creating I and Q signals; and (c) continuously detecting and correcting errors between the I and Q channels.
-
-
44. The method of claim 43 wherein the passband bandwidth is about the channel spacing wide.
-
45. An apparatus for tuning a channel of interest from a channelized spectrum having a predetermined channel spacing, the apparatus comprising:
-
(a) a local oscillator configured to generate approximately phase-quadrature local oscillator signals; (b) a filter configured to define a near-baseband passband; (c) mixers, each responsive to one of the phase-quadrature local oscillator signals and the signal of interest, that frequency-translate the signal of interest creating I and Q signals that fall within the near-baseband passband; and (d) an operating-temperature sensor coupled to correct errors between the I and Q signals.
-
-
46. The apparatus of claim 45 wherein the near-baseband passband is frequency-spaced from DC by at least about the channel spacing.
-
47. The apparatus of claim 45 wherein the bandwidth of the near-baseband passband is about a channel spacing.
-
48. The apparatus of claim 45 wherein the operating-temperature sensor is coupled to generate a correction factor selected to optimize unwanted signal rejection.
-
49. The apparatus of claim 45 wherein the sensor is coupled to correct errors between the I and Q signals through a digital controller.
-
50. A method of tuning comprising:
-
(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing; (b) mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; (c) frequency translating the channel of interest to a near-baseband passband that has a width equal to about the channel spacing plus a fine tuning adjustment; (d) fine tuning the channel of interest by passing a selected range of passband; (e) sensing the operating temperature of the tuning device; and (f) using the sensed temperature to correct errors between the I and Q channels.
-
-
51. The method of claim 50 wherein correcting errors comprises choosing one or more correction factors to optimize image rejection.
-
52. The method of claim 50 wherein the passband is spaced from DC by at least about the channel spacing.
-
53. The method of claim 50 wherein fine tuning of the channel of interest is done by digitally controlled variable passband filtering.
-
54. A tuning method comprising, with a tuning device:
-
(a) receiving a channel of interest from a channelized spectrum having a predetermined channel spacing; (b) mixing the channel of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q channels; (c) frequency translating the channel of interest to a near-baseband passband that has a width equal to about the channel spacing; (d) dynamically varying the passband bandwidth; (e) further translating the frequency-translated channel of interest to baseband by mixing the frequency-translated channel of interest with a second local oscillator signal; and (f) sensing the operating temperature of the tuning device and using the sensed temperature information to correct errors between the I and Q channels.
-
-
55. The method of claim 54 wherein the lower edge of the passband is spaced from DC by at least about the channel spacing.
-
56. The method of claim 54 wherein the passband is varied to follow variations in the channel of interest.
-
57. The method of claim 54 wherein the second local oscillator signal has a frequency that is approximately the center frequency of the frequency-translated channel of interest.
-
58. The method of claim 57 further comprising fine-turning the translation to baseband of the frequency-translated channel of interest by adjusting the second local oscillator frequency.
-
59. The method of claim 58 wherein the frequency translation to baseband is done in the digital domain.
-
60-78. -78. (canceled)
-
79. A method of tuning a signal of interest from a channelized spectrum, comprising:
-
(a) splitting an incoming signal into two signal paths; (b) generating an approximately quadrature local oscillator signal; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) filtering the I signal with a first passband filter and filtering the Q signal with a second passband filter, wherein each filter defines a near-baseband passband, the lower edge of which is spaced from DC by at least about the passband width; (e) subjecting one of the filtered I and Q signals to a phase shift of about 90 degrees relative to the other, thereby producing second I and Q signals; and (f) summing the second I and Q signals, thereby producing a real-valued signal.
-
-
80. The method of claim 79 wherein the relative phase shift is implemented with a Hilbert transform pair.
-
81. The method of claim 79 further comprising filtering the real-valued signal with a third passband filter and demodulating the real-valued signal.
-
82. The method of claim 81 wherein the third bandpass filter is adjustable.
-
83. The method of claim 79 further comprising implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
84. The method of claim 83 wherein implementing error correction comprises continuously detecting and correcting errors.
-
85. The method of claim 79 wherein generating the approximately quadrature local oscillator signal comprises generating the signal from a local oscillator that is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of a channel spacing of the channelized spectrum.
-
86. The method of claim 85 wherein the local oscillator signal is one-half of a channel spacing displaced from an integer multiple of the channel spacing.
-
87. The method of claim 79 wherein the lower edge of the near-baseband passband is spaced from DC by at least about a channel spacing of the channelized spectrum.
-
88. The method of claim 87 wherein the lower edge of the near-baseband passband is spaced from DC by about a channel spacing and the near-baseband passband has a width equal to about the channel spacing.
-
89. The method of claim 88 further comprising:
-
(a) filtering the real-valued signal with a third passband filter; (b) demodulating the filtered real-valued signal; and (c) implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
-
90. The method of claim 79 wherein the lower edge of the near-baseband passband is spaced from DC by at least about the maximum bandwidth of the signal of interest.
-
91. The method of claim 90 wherein the lower edge of the near-baseband passband is spaced from DC by about the maximum bandwidth of the signal of interest and the near-baseband passband has a width equal to about the maximum bandwidth of the signal of interest.
-
92. The method of claim 91 further comprising:
-
(a) filtering the real-valued signal with a third passband filter; (b) demodulating the filtered real-valued signal; and (c) implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
-
93. The method of claim 79 further comprising converting the filtered I and Q signals to digital I and Q signals, wherein the second I and Q signals and the real-valued signal are digital signals.
-
94. The method of claim 93 further comprising filtering the real-valued digital signal with a digital passband filter and digitally demodulating the real-valued digital signal.
-
95. Apparatus for tuning, from a channelized spectrum having a predetermined channel spacing, a channel of interest, the apparatus comprising:
-
(a) a local oscillator configured to generate a quadrature local oscillator signal; (b) an amplifier responsive to an RF signal of interest; (c) a pair of mixers that are responsive to the amplified signal of interest and the quadrature local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) a first passband filter responsive to the I signal and a second passband filter responsive to the Q signal, wherein each filter defines a near-baseband passband, the lower edge of which is spaced from DC by at least about the passband width; and (f) a summer responsive to. (1) a first one of the filtered I and Q signals from the first and second passband filters, and. (2) a version of the second one of the filtered I and Q signals that has been subjected to a phase shift of about 90 degrees relative to the first one of the filtered I and Q signals.
-
-
96. The apparatus of claim 95 further comprising a Hilbert transform pair responsive to the filtered I and Q signals, thereby subjecting one of the filtered I and Q signals to a phase shift of about 90 degrees relative to the other.
-
97. The apparatus of claim 95 further comprising a third passband filter responsive to a real-valued signal from the summer and a demodulator responsive to a filtered real-valued signal from the third passband filter.
-
98. The apparatus of claim 97 wherein the third bandpass filter is adjustable.
-
99. The apparatus of claim 95 wherein the local oscillator is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of a channel spacing of the channelized spectrum.
-
100. The apparatus of claim 99 wherein the local oscillator is configured to generate the quadrature local oscillator signal at frequencies one-half of a channel spacing displaced from integer multiples of the channel spacing.
-
101. The apparatus of claim 95 wherein the lower edge of the near-baseband passband is spaced from DC by at least about a channel spacing of the channelized spectrum.
-
102. The apparatus of claim 101 wherein the lower edge of the near-baseband passband is spaced from DC by about a channel spacing and the near-baseband passband has a width equal to about the channel spacing.
-
103. The apparatus of claim 95 wherein the lower edge of the near-baseband passband is spaced from DC by at least about the maximum bandwidth of the signal of interest.
-
104. The apparatus of claim 103 wherein the lower edge of the near-baseband passband is spaced from DC by about the maximum bandwidth of the signal of interest and the near-baseband passband has a width equal to about the maximum bandwidth of the signal of interest.
-
105. The apparatus of claim 95 further comprising a pair of analog-to-digital converters response to the filtered I and Q signals from the first and second passband filters, respectively, wherein the summer is responsive to digital signals.
-
106. The apparatus of claim 105 further comprising a digital passband filter responsive to a real-valued digital signal from the summer and a digital demodulator responsive to a filtered real-valued digital signal from the digital passband filter.
-
107. A method of tuning a channel of interest from a channelized spectrum, comprising:
-
(a) splitting an incoming signal containing a channel of interest into two signal paths; (b) generating an approximately quadrature local oscillator signal; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby producing I and Q signals in approximate quadrature relation; (d) filtering the I signal with a first filter and filtering the Q signal with a second filter; (e) subjecting one of the filtered I and Q signals to a phase shift of about 90 degrees relative to the other, thereby producing second I and Q signals; and (f) summing the second I and Q signals, thereby producing a real-valued signal; (g) wherein the channel of interest is frequency translated to within a near-baseband passband, the lower edge of which is spaced from DC by at least about the channel spacing.
-
-
108. The method of claim 107 wherein the relative phase shift is implemented with a Hilbert transform pair.
-
109. The method of claim 107 further comprising implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
110. The method of claim 109 wherein implementing error correction comprises continuously detecting and correcting errors.
-
111. The method of claim 107 wherein generating the approximately quadrature local oscillator signal comprises generating the signal from a local oscillator that is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of a channel spacing of the channelized spectrum.
-
112. The method of claim 111 wherein the local oscillator signal is one-half of a channel spacing displaced from an integer multiple of the channel spacing.
-
113. The method of claim 111 wherein the lower edge of the near-baseband passband is spaced from DC by about a channel spacing and the near-baseband passband has a width equal to about the channel spacing.
-
114. The method of claim 113 further comprising:
-
(a) demodulating the real-valued signal; and (b) implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
-
115. The method of claim 107 wherein the lower edge of the near-baseband passband is spaced from DC by at least about the maximum bandwidth of the signal of interest.
-
116. The method of claim 115 wherein the near-baseband passband has a width equal to about the maximum bandwidth of the signal of interest.
-
117. The method of claim 116 further comprising:
-
(a) demodulating the real-valued signal; and (b) implementing error correction between I and Q signals to maximize rejection of unwanted mixing images.
-
-
118. The method of claim 107 further comprising converting the I and Q signals to digital I and Q signals, wherein the second I and Q signals and the real-valued signal are digital signals.
-
119. The method of claim 118 further comprising filtering the real-valued digital signal with a digital passband filter and digitally demodulating the real-valued digital signal.
-
120-125. -125. (canceled)
-
126. A method for tuning a signal of interest from within a channelized spectrum, the method comprising:
-
(a) splitting an incoming signal into two signal paths; (b) generating an approximately quadrature local oscillator signal from a local oscillator that is coarse-tunable across the channelized spectrum with a step size that is an integer multiple of the channel spacing; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby; (1) frequency translating to a near-baseband passband an upper high frequency spectrum of interest from above the frequency of the local oscillator signal and a lower high frequency spectrum of interest from below the frequency of the local oscillator signal, the near-baseband passband being defined with reference to a lower frequency F1 and an upper frequency F2, wherein F1=F2−
F1 and F1 is at least about the maximum bandwidth of the signal of interest; and(2) producing I and Q signals in approximate quadrature relation; (d) limiting the frequency spectrum of the I and Q signals, wherein spectrum coverage is provided of a selected one of the high frequency spectra of interest and analog processing of signals at or close to DC is avoided; and (e) repeating. (a) through. (d) in turn for a plurality of local oscillator frequencies, wherein high frequency spectra of interest tunable with the local oscillator frequencies of the plurality are interspersed among local oscillator frequencies of the plurality within the channelized spectrum.
-
-
127. The method of claim 126 wherein limiting the frequency spectrum of the I and Q signals comprises filtering the signals in continuous-time using switched-capacitor circuitry.
-
128. The method of claim 126 wherein limiting the frequency spectrum of the I and Q signals comprises highpass and lowpass filtering the signals in continuous-time.
-
129. The method of claim 128 wherein limiting the frequency spectrum of the I and Q signals further comprises filtering the signals in discrete-time.
-
130. The method of claim 126 further comprising:
-
(a) converting the I and Q signals to digital I and Q signals; and (b) combining the digital I and Q signals to reject an undesired mixing image.
-
-
131. The method of claim 130 further comprising correcting amplitude and phase errors between the digital I and Q signals.
-
132. The method of claim 1 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
133. The method of claim 11 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
134. The method of claim 21 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
135. The method of claim 26 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
136. The method of claim 28 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
137. The apparatus of claim 31 wherein the local oscillator signal frequency is dynamically selectable to track frequency movement of the channel of interest.
-
138. The apparatus of claim 32 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
139. The method of claim 37 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
140. The method of claim 40 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
141. The method of claim 43 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
142. The apparatus of claim 45 wherein the local oscillator signal is dynamically selectable to track frequency movement of the channel of interest.
-
143. The apparatus of claim 46 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
144. The method of claim 50 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
145. The method of claim 52 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
146. The method of claim 54 further comprising dynamically selecting the frequency of the local oscillator signal to track frequency movement of the channel of interest.
-
147. The method of claim 55 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
148. The method of claim 60 wherein further translating the frequency-translated channel of interest comprises translating the frequency-translated channel of interest to baseband.
-
149. The method of claim 60 further comprising dynamically selecting the frequency of the first local oscillator signal to track frequency movement of the channel of interest.
-
150. The apparatus of claim 73 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
151. The apparatus of claim 78 wherein the near-baseband passband is spaced from DC by about the channel spacing.
-
152. A method of tuning a signal of interest from a channelized spectrum, comprising:
-
(a) receiving a signal of interest from a channelized spectrum having a predetermined channel spacing; (b) mixing the signal of interest with approximately phase-quadrature local oscillator signals, thereby creating I and Q signals; and (c) frequency translating the signal of interest to a near-baseband passband that is spaced from DC by about the passband width; (d) wherein the local oscillator signals have a frequency that is selected to dynamically track frequency movement of the signal of interest; (e) the signal of interest lies within one of an upper high frequency spectrum of interest and a lower high frequency spectrum of interest; and (f) the method further comprises providing spectrum coverage within one of the high frequency spectra of interest and not the other.
-
-
153. The method of claim 154 wherein the frequency of the local oscillator signals is one-half of a channel spacing displaced from an integer multiple of the channel spacing.
-
154. The method of claim 152 wherein the lower edge of the near-baseband passband is spaced from DC by at least about a channel spacing of the channelized spectrum.
-
155. The method of claim 154 wherein the lower edge of the near-baseband passband is spaced from DC by about a channel spacing and the near-baseband passband has a width equal to about the channel spacing.
-
156. The method of claim 152 wherein the lower edge of the near-baseband passband is spaced from DC by at least about the maximum bandwidth of the signal of interest.
-
157. The method of claim 156 wherein the lower edge of the near-baseband passband is spaced from DC by about the maximum bandwidth of the signal of interest and the near-baseband passband has a width equal to about the maximum bandwidth of the signal of interest.
-
158-163. -163. (canceled)
-
164. A method of tuning a signal of interest having a predetermined bandwidth, comprising:
-
(a) splitting an incoming signal into two signal paths; (b) generating an approximately quadrature local oscillator signal; (c) quadrature mixing the split incoming signal with the local oscillator signal, thereby frequency translating the signal of interest to within a near-baseband passband that. (1) is spaced from DC by at least about the maximum bandwidth of the signal of interest, and. (2) is about as wide as said maximum bandwidth; and (e) filtering the frequency translated signal of interest with a bandpass filter having a variable passband.
-
-
165. The method of claim 1 wherein the lower edge of the near-baseband passband is spaced from DC by about 1.5 times the maximum bandwidth of the signal of interest.
-
166. The method of claim 1 wherein the bandpass filter having a variable passband is a digital filter.
Specification