Abstract: A common intermediate frequency broadcast radio front end. The invention employs a common front end that employs a common mixer and intermediate frequency for both AM and FM radio signals. Borrowing on the inherent advantages of employing a substantially reduced intermediate frequency, when compared to the elevated intermediate frequency that is employed in many conventional systems, the invention provides for the ability to employ components whose precision is significantly relaxed and whose cost is substantially reduced. The low frequency affords the ability to use relatively cheap ceramic filters and integrated filters within the IC instead of relatively expensive crystal filters commonly employed at higher intermediate frequencies. In addition, the implementation of a common mixer for both AM and FM signals results in a savings of real estate on the silicon die used to operate certain embodiments of the invention.

Abstract: A method of avoiding conversion spurs in a multi-conversion radio frequency receiver having a first local oscillator, an intermediate frequency filter and a second local oscillator in series generates, based on a center frequency for the intermediate frequency filter, a table of problem frequencies of the first local oscillator relative to a frequency of the second local oscillator which produce harmonic mixing products within the bandwidth of the intermediate frequency filter versus corresponding frequency offsets for the second local oscillator which retune the frequency of the second local oscillator so the harmonic mixing products are moved outside the bandwidth of the intermediate frequency filter.

Abstract: In accordance with a method for single-carrier and multi-carrier reception, the following steps are executed: downconverting a received RF signal to in-phase (I) and quadrature (Q) channel signals each containing a plurality of sub-carriers at a low intermediate frequency (low-IF) and, if required, one sub-carrier or a single carrier centered around 0 Hz; filtering interfering signals outside of a frequency band of interest with analog lowpass filters in the I and Q channels; converting the I and Q channel signals to digital representations thereof; in the multi-carrier reception case, separating sub-carriers that are images of one another by quadrature downmixing the digital representations of the I and Q channel signals to baseband in the digital domain; and digitally adding or subtracting resulting I and Q signals to obtain one or both of an upper sideband and a lower sideband containing desired ones of the multi-carriers.

Abstract: A receiver (54) comprising an input for receiving an RF signal (FIG. 7) centered at a first frequency and having a bandwidth. The receiver also comprises a first mixer (62) for producing a first output signal. The first output signal results from mixing the RF signal with a signal having an energy spreading portion (p(t)) and a down-converting portion (c(t)). Moreover, this first output signal comprises a self-mixing DC signal (c(t)p(t) self-mixing DC component) and a down-converted and energy spread RF signal (FIG. 11). The receiver further comprises a second mixer (70) for producing a second output signal by mixing a signal responsive to the first output signal with the energy spreading portion of the signal. The second output signal comprises two signals, namely: (1) a baseband signal (down-converted RFA1) responsive to the down-converted and energy spread RF signal; and (2) a portion of the spread DC signal (spread DC).

Abstract: A communication system with variable filter bandwidth includes a first mixer circuit configured to receive a communication signal and shift the frequency range of the communication signal to a first frequency range. A second mixer circuit is configured to receive the same communication signal and shift the frequency range of the communication signal to a second frequency range. An activation circuit is coupled to the first and second mixer circuits so as to provide an activation signal that activates at least one of the mixer circuits. A plurality of filter circuits are provided such that each filter circuit is configured to receive a signal from a corresponding mixer circuit, when said corresponding mixer circuit is activated.

Abstract: A wireless mobile terminal for a wireless communication system comprises a wireless transceiver, a global positioning system (GPS) receiver, wherein the wireless transceiver and the GPS receiver share a frequency reference signal. The frequency reference signal can be multiplied by an integer multiple to create a first local oscillator for a signal conversion to an intermediate frequency for signal processing of the GPS signal. In addition, the frequency reference signal can also be divided into a lower frequency to create a second local oscillator for a conversion to a second intermediate frequency. The frequency reference signal can also be divided to create a frequency necessary for other signal processing, such as an analog-to-digital converter sampling signal at the GPS receiver. The frequency reference signal can be taken from different places within the frequency synthesis mechanism of the wireless transceiver.

Abstract: This invention provides a multistage frequency multiplier having a plurality of frequency doublers. Each doubler incorporates a three-terminal transistor device and is connected to an adjacent doubler via an interstage network. The network comprises a transmission line having its electrical parameters selected to achieve conjugate impedance matching at the intermediate harmonic frequency generated by the corresponding doubler. This network also includes a quarter-wavelength open-ended stub for suppressing a main input frequency component received by the corresponding frequency doubler. A shunt resistor on the transistor gate is preferably used to stabilize the network. This interstage network simplifies overall circuit topology to reduce total circuit size, and provides increased drive power levels to permit broader bandwidth and stabilize required output level from a local oscillator.

Abstract: A phase-linear wide band converter for frequency conversion from a multi-octave baseband (BB) to an RF band or vice versa and utilizing I/Q signal processing. The converter uses a phase-linear power divider/combiner having three ports, an I/Q mixer stage, an I/Q power divider for an I/Q local oscillator (LO) signal, two wide band balanced mixers, and impedance matching circuits.

Abstract: An image suppression filter circuit comprises a first phase shifter outputting a first output signal and a second output signal substantially orthogonal thereto, a second phase shifter outputting a third output signal and a fourth output signal orthogonal to the third output signal, a first subtracter subtracting the fourth output signal from the first output signal, a first adder adding the second and third output signals, a third phase shifter outputting a fifth output signal and a sixth output signal orthogonal to the fifth output signal, a fourth phase shifter outputting a seventh output signal and an eighth output signal orthogonal thereto, a second subtracter subtracting the eighth output signal from the fifth output signal, and a second adder adding the sixth and the seventh output signals.

Abstract: A radio such as a frequency division duplex (FDD) radio (100) has a first local oscillator (LO1I and LO1Q) that is set to coincide with the transmitter section's (126) center frequency or a sub-harmonic thereof. In this way, after the first down-conversion, the transmit interferer is converted to DC, where it can be effectively removed using a simple high-pass filter (110, 112) such as a DC blocking capacitor. Image rejection is achieved by the use of a two-step down-conversion approach that uses quadrature local oscillators to implement a single-sideband down-converter.

Abstract: In a communications terminal that has an image reject mixing arrangement, a compensation system provides compensation for phase and amplitude imbalances, which are caused by a demodulating local oscillator employed in the communications terminal. The image reject mixing arrangement comprises a radio-frequency (RF) mixing stage including an in-phase and a quadrature phase branch, which is configured to receive a radio frequency signal and down convert the radio frequency signal to in-phase and quadrature phase intermediate frequency (IF) signals. It also includes a phase splitter unit coupled to the radio-frequency (RF) mixing stage and configured to provide an in-phase local oscillator signal and a quadrature phase local oscillator signal to the RF mixing stage. The phase splitter causes an amplitude imbalance signal &Dgr; and a phase imbalance signal &phgr; to be generated in the in-phase and quadrature phase branch of the RF mixing stage.

Abstract: A frequency conversion circuit has a first frequency conversion stage with a first mixer, a second conversion stage with a second mixer, an oscillator, a first frequency divider, and a second frequency divider. The first frequency divider is directly connected between the oscillator and an input of the first mixer. The second frequency divider is coupled between the oscillator and an input of the second mixer. The first and second frequency dividers can either be connected in series or parallel.

Abstract: A single chip superhetrodyne AM receiver is disclosed herein. To compensate for process variations in the implementation of the IC, bias currents setting the operating conditions for various amplifiers and other components in the system are adjusted based on frequency control signals in a PLL circuit in the local oscillator. Since the magnitude of the control signal reflects the process variations, the bias currents are adjusted based on the control signal to offset these variations in other portions of the receiver. To further improve the signal to noise ratio of the receiver, the IF filter is tuned within a range so as not to include any integer multiple or integer divisor of the timing reference frequency. Various techniques are described for enabling a complete superhetrodyne AM receiver to be implemented on a single chip which receives an antenna input signal and outputs a digital data signal.

Abstract: This invention is a modular active filter that can be inserted between the antenna and a filter of a pre-existing unit, so that it can still function normally, without noise from cellular phones. This unit is modular. A heterodyning unit is used with a prefilter/amplifier unit and a post-filter/amplifier unit. After down converting the signal, while heterodyning, the signal is put through at least one crystal filter to filter out the noise introduced by cellular phones. To make sure that the unit works well with a wide variety of antenna-receiver pairs, the resonant frequency of the filters of the pre and post amplifier/filter units is set to the center frequency that the antenna and receiver are designed to handle. In this way, only one type of unit needs to be manufactured for each frequency band. An example of such an operating frequency might be 900 MHz. This invention has two types of embodiments. In one type embodiment the local oscillator produces only one fixed frequency.

Abstract: In the receiver using a PLL synthesizer, there is a limit in reducing boot-up time or frequency switching time, which shortens battery life. A first local frequency L01 from a multiplier 22 and a receiving signal are input to a first frequency converter 10 to convert it to a first intermediate frequency IF1. The first intermediate frequency IF1 is converted in a second frequency converter 12 by a frequency L02 of an N1 frequency divider 24 to a second intermediate frequency IF2. Also, the outputs of the N1 frequency divider 24 and N2 frequency divider 26 are mixed in the frequency converter for transmission 34, and L04 and the local frequency L01 are added to a lower-side-band cancel mixer 50 to extract the upper side band of the transmission frequency.

Abstract: This invention relates to a radio transceiver operable in multiple modes. The transceiver is operable, in one embodiment, to communicate with digital and analogue modulation format cellular radio systems. The handset utilizes a novel frequency plan and architecture to enable a minimum level of complexity for dual-moe operation. The frequency plan preferably uses two local oscillators 1LO, 2LO to general all the required frequencies for both the digital and analogue modulation format transceivers, derived from a single reference crystal oscillator. A radio architecture is used to enable switchable dual-mode operation with maximum commonality of functional blocks to facilitate silicon integration.

Abstract: A radio receiving apparatus has a receiving section for receiving a radio signal, a local oscillating section for generating a first local oscillation signal and a second local oscillation signal, wherein the first local oscillation signal and the second local oscillation signal have each of a first frequency and a second frequency differing from a received frequency. The apparatus also has a frequency converting section for mixing the received signal output from the receiving section and the first local oscillation signal to output an intermediate frequency signal and an orthogonal converting section for orthogonal converting the intermediate frequency signal output with the second local oscillation signal.

Abstract: A dual band user terminal (10) includes a controller (18) for outputting a BAND signal for specifying operation in one of a first frequency band or a second, higher frequency band; a single frequency synthesizer (46) that is responsive to the BAND signal for outputting an RF signal in one of two frequency bands; and an RF transceiver (11) comprising a dual band receiver that receives RF signals in the first frequency band and in the second, higher frequency band, and a dual band transmitter that transmits RF signals in the same frequency bands.

Abstract: A first local signal required for a downconverter of a reception system and an upconverter of a transmission system in a first band is generated by a synthesizer for generating a variable high frequency local signal. A second local signal required for a downconverter of a reception system and an upconverter of a transmission system in a second band is generated by mixing a signal generated by an oscillator for generating a signal at a relatively low fixed frequency with the first local signal using a mixer and filtering the result using a high-pass filter.

Abstract: A method and apparatus for generating two disparate frequency reference signals using a single phase locked loop. The circuit includes a local oscillator for generating a reference signal and a phase comparator for comparing the reference signal with a feedback signal. The output of the phase comparator is converted to a first one of the desired output frequencies by a voltage controlled oscillator. That signal is also fed to a variable frequency divider circuit under control of a &Sgr;/&Dgr; converter which generates a lower frequency signal without creating a secondary frequency tone. The lower frequency signal is the second of the output frequencies. This signal also is fed back to the second input of the phase comparator through a fixed frequency divider.

Abstract: A novel frequency scheme for a police radar detector enables improved sweeping of the X, K, Ku and Ka radar bands. The novel frequency scheme requires two initial frequency conversions for detection of the X, K and Ka radar bands and a single initial frequency conversion for the Ku radar band with single initial frequency conversion being enabled by disabling the second mixer. During sweeping of the X, K and Ka bands, selectable, i.e., upper or lower, sideband suppression is employed to reduce undesired image sidebands and noise prior to the second frequency conversion. In addition, noise at the second IF frequency is reduced to prevent this noise from feeding through the second mixer into the second IF amplifier. During the Ku band sweep, the second mixer is bypassed and shunting of signals at the second IF frequency is disabled so that these signals enter the second IF amplifier.

Abstract: A single chip superhetrodyne AM receiver including a local oscillator which sweeps through a frequency range at a rate higher than a modulation frequency of the incoming RF signal. The local oscillator frequency is mixed with the incoming RF signal. An IF filter passes a selected frequency band from the mixer to a demodulator. The demodulator is tuned to demodulate any signal within a band of frequencies determined by the sweeping of the local oscillator. This increases the signal to noise ratio of the receiver since it allows for variations in the transmitter output frequency. The frequency responses of the various filters are tied to the reference frequency and allows the user to set the tuning and alignment of the receiver. To compensate for process variations in the implementation of the IC, bias currents setting the operating conditions for various amplifiers and other components in the system are adjusted based on frequency control signals in a PLL circuit in the local oscillator.

Abstract: A frequency translation circuit (10) translates an incoming reference signal (RF.sub.IN) to a lower frequency using a compound mixer circuit (42). The compound mixer circuit (42) has a first mixer circuit (14A) that receives both the incoming reference signal (RF.sub.IN) and a signal generated by a first counter (28A). A second mixer circuit (14X) of the compound mixer circuit (42) receives a signal generated by a second counter (28X) and further translates the signal received from the first mixer circuit (14A) to a lower frequency. Both the first mixer circuit (14A) and the second mixer circuit (14X) generate output signals having a carrier frequency that is lower in frequency by the difference of the two input signals.

Abstract: An image rejection circuit (10) receives an incoming signal (RF.sub.IN) and an oscillator signal (V.sub.OSC) generated by a local oscillator (26). Output signals (I.sub.OUT20 and I.sub.OUT40) are generated by first mixer circuits (14 and 34) by multiplying the incoming signal (RF.sub.IN) with the oscillator signal (V.sub.OSC) Second mixer circuits (24 and 44) multiply the output signals (I.sub.OUT20 and I.sub.OUT40) with a counter signal that is a divided oscillator signal (V.sub.OSC). A summing circuit (46) sums the signals generated by the second mixer circuits (24 and 44) and provides a signal (IF.sub.OUT). Phase shift circuits (22, 29, 31, and 42) provide a shifted oscillator signal (V.sub.OSC) and a shifted counter signal to the first and second mixer circuits (14, 24, 34, and 44) that cause cancellation of unwanted image signals in the signal (IF.sub.OUT).

Abstract: A radio transceiver system uses a single variable local oscillator frequency source which is used in mixing both before and after a band-pass filter. This causes a reduction in band-pass filter bandwidths. In an all-band transceiver for PCS for example the effect of this reduced bandwidth requirement is to increase the spacing between the transmit bands and the receive bands and thereby enable a reduction in transmission noise interfering with the reception bands.

Abstract: A radio receiver, and a method therefore, for efficiently suppressing attenuation properties of a low frequency signal, in an analog frequency modulation type radio communication system. The radio receiver includes a first down-converter for mixing a modulated, high-frequency signal received by the radio receiver and a predetermined local oscillating signal to generate an intermediate frequency signal. A modulator modulates the predetermined local oscillating signal by an aural signal transmitted from the transmitter and generates a mixing signal for down-mixing the electrical signal representative of modulated, high-frequency signal. The mixed signal is then applied to the first down-converter. A second down-converter down-converts, in frequency, the intermediate frequency signal generated from the first down-converter into a baseband signal to generate the down-converted signal.

Abstract: An improved receiver architecture utilizing active filters for frequency conversion, wherein the final IF stage operates at a frequency higher than the previous IF stage, is disclosed to facilitate the processing by a baseband system operating at higher IF of signals from receivers operating at lower IFs and to enable the continued use of existing post-IF devices with multiple-conversion receivers. A low IF signal output is digitally mixed with a divided local oscillator signal to achieve a higher IF which is suited for processing by post-IF components such as a detector. The mixed signal is then filtered by a low dynamic range active filter and limited.

Abstract: A radio frequency generator in a radio communication system having a transmitter for up-converting the frequency of transmission data signals, and a receiver for down-converting the frequency of reception data signals includes: a first radio frequency generator for generating a low-band reception local oscillator frequency signal which is provided to a second mixer in the receiver; a second radio frequency generator for generating a low-band transmission local oscillator frequency signal which is provided to a first mixer in the transmitter; and a third radio frequency generator for generating a high-band local oscillator frequency signal for a first mixer of the receiver and a second mixer of the transmitter. A reference frequency generator is provided for receiving a radio frequency signal from a global position system receiver and generating a reference signal for generating local oscillator frequency signals in response thereto.

Abstract: The invention provides a superheterodyne receiver by which undesired radiations are minimized. The superheterodyne receiver includes a voltage-controlled oscillator for forming an oscillation signal of a frequency equal to n times a carrier frequency of an object FM signal, and a frequency divider for dividing the frequency of the oscillation signal to the carrier frequency. The superheterodyne receiver further includes a pair of first mixers for frequency converting the object received signal into a pair of first intermediate-frequency signals using signals from the frequency divider as a first local oscillation signal, and a pair of second mixers for converting the first intermediate-frequency signals into a second intermediate-frequency signal with the second local oscillation signals. The superheterodyne receiver further includes a demodulator for demodulating the second intermediate-frequency signal into an original signal.

Abstract: An amplifier system (100) for transmitting wideband multicarrier communication signals in a satellite communication system uses wideband envelope elimination and restoration amplifiers (200). The system upconverts channelized IF signals to provide a wideband multicarrier RF output signal between 20 and 30 GHz having a bandwidth between 100 and 200 MHz.

Abstract: A multiband mobile unit communication apparatus comprises: antennas for receiving plural radio wave SIGs respectively transmitted from plural mobile unit communication systems, the plurality of radio wave SIGs having different carrier frequencies respectively; independent CKTs for generating IF SIGs from the radio wave SIGs from the antennas respectively; and a common CKT including a switch according to a mode SIG, a quadrature demodulation CKT for directly converting the IF SIG from the switch into I and Q baseband SIGs, and a decoding CKT for outputting a decoding result from said I and Q baseband SIGs. In accordance with the mode SIG, power is selectively supplied to the independent CKTs, a switchable FRQ-divider may be provided to FRQ-dividing a LO SIG for the quadrature demodulation CKT, a switchable tuning CKT may be provided to the variable gain amplifying CKT to provide a switchable tuning FRQ, switchable low-pass filters may be provided to switchably low-pass-filter the I and Q baseband SIGs.

Abstract: In a complex signal receiver, quadrature imbalances in phase angle and amplitude are detected and compensated. A known signal is applied to a quadrature receiver and converted into inphase and quadrature baseband signals. A signal processor determines an imbalance between the inphase and quadrature signals of the known signal and generates one or more correction factors in response to the determined imbalance. The correction factors are applied to subsequently received inphase and quadrature baseband signals to minimize the imbalance between the subsequently received inphase and quadrature baseband signals. The imbalance compensation and correction technique is also useful to quadrature transmitters that employ feedback control. The quadrature imbalance detection and correction circuitry may be integrated on the same integrated circuit chip as the receiver circuitry to provide a single, universal receiver chip.

Abstract: A double superheterodyne type receiving circuit having a first local oscillating circuit for converting a received signal into a first intermediate frequency signal and a second local oscillating circuit for converting the first intermediate frequency signal into a second intermediate frequency signal, comprising an oscillator 16 composing the first local oscillating circuit, a first variable frequency divider 17 composing the second oscillating circuit for dividing the frequency of an output signal of the first oscillator, a second variable frequency divider 18 for dividing the frequency of an output signal of the first variable frequency divider, a variable frequency dividing controlling circuit 23 for controlling frequency dividing values of the first and second variable frequency dividers on the base of an exponential function relation, at least one fixed frequency divider 19 for dividing the frequency of an output signal of the second variable frequency divider 18, a reference oscillator 20 for outputtin

Abstract: An apparatus for extending the practical lengths over which coaxial cables can be used to transfer signal information from a Global Positioning System (GPS) antenna to a GPS receiver. The apparatus converts the GPS signal frequency of 1.57542 GHz to a frequency low enough to be transferred long distances over coaxial cables without significant signal attenuation and then converts the signal back to the original frequency without the introduction of frequency errors. The invention is not restricted from being used at other frequencies where system design parameters makes it practical.

Abstract: In a direct conversion receiver with an AFC function comprising a local oscillation circuit constituted by a synthesizer, the local oscillation frequency is prevented from radiating as an interfere wave against the receiver per se so as not to reduce the reception characteristic, and it is made possible to reduce the value of the multiplication factor N of a multiplier in the synthesizer without making the frequency of a VCO per se high. Specifically, a first local oscillation signal 12 obtained by multiplying an output frequency F.sub.X of a reference crystal oscillation circuit portion 8 of a synthesizer circuit section 7 by M by a multiplier 11 is mixed with an FSK modulation signal 1 in a first mixer 4. In a second mixer 5, the thus mixed signal is further mixed with a second local oscillation signal 13 obtained by multiplying an output frequency F.sub.V of a synthesizer 9 by N by a multiplier 10.

Abstract: A radio receiver is disclosed. An arbitrary receive signal received through an antenna is amplified by an input amplifier. The signal amplified by the input amplifier is converted into a predetermined frequency by a mixer. The signal frequency-converted by the mixer is shaped in waveform by a band-limiting filter. The signal thus shaped in waveform is amplified and amplitude-limited by a limiting amplifier. The signal limited in amplitude is demodulated by a demodulator. In order to prevent the mixer circuit from generating a distortion due to an excessive input, another amplitude-limiting circuit operated at a level not saturating the mixer circuit is arranged in a stage before the mixer circuit.

Abstract: A multiband mobile unit communication apparatus is disclosed which comprises: an antenna for receiving 1st and 2nd bands of radio wave SIGs including quadrature modulation SIGs; a 1st LO CKT for generating a 1st LO SIG; 1st and 2nd receiving CKTs for generating 1st and 2nd IF SIGs from the 1st and 2nd bands of radio wave SIGs using the 1st LO SIG respectively; a switching CKT responsive to a switching control SIG indicative of 1st and 2nd modes for outputting the 1st IF SIG in the 1st mode and outputting the 2nd IF SIG in the 2nd mode; a 2nd LO CKT for generating 2nd and 3rd LO SIGs in the 1st and 2nd modes respectively; and a quadrature demodulation CKT for demodulating and outputting quadrature SIGs from an output from the switching CKT using the 2nd and third LO SIGs in the 1st and 2nd modes respectively.

Abstract: A satellite navigation receiver uses common dual-conversion superheterodyne and frequency synthesiser circuitry for receiving signals from both the GPS and the GLONASS satellite navigation systems. Successive first and second frequency down-converters in the receiver chain are fed by first and second local oscillator signals which are both variable in frequency such that the frequency of the first local oscillator signal is an integral multiple (preferably 8) of the second local oscillator signal. This relationship is provided by a binary divider (32) at least a portion of which may form part of a digital frequency synthesiser loop.

Abstract: The invention relates to a transceiver for generating complex I/Q-signals on a transmission frequency (f.sub.TX) and for receiving them on a reception frequency (f.sub.RX). The device comprises a first frequency synthesizer (41) for forming a first mixer signal (f.sub.LI) for the mixer (42) of the first branch that mixes the I-component of the received signal into a lower-frequency I-signal, and a second frequency synthesizer (411, 49, 46) for forming a second mixer signal (f.sub.LQ) for the mixer (421) of the second branch that mixes the Q-component of the received signal into a lower-frequency Q-signal. The device further comprises control means (45) first for directing the phase of the first (f.sub.LI) and the second (f.sub.LQ) mixer signals into the same phase in the mixing effects thereof and, thereafter, into a 90 degree mutual phase shift in the mixing effects thereof when receiving signals for bringing the lower-frequency I- and Q-signals into a 90 degree mutual phase shift.

Abstract: A GPS frequency converter is provided, according to the present invention, to down-convert the frequency of an incoming GPS signal. The converter includes first and second mixers, the former of which receives the incoming RF signal and a signal from a local oscillator. The local oscillator signal is increased by a factor of 98 and then subtracted from the incoming RF signal to produce a first intermediate frequency signal (IF). The first IF signal is then passed to the second mixer which subtracts the frequency of the local oscillator therefrom to produce a second intermediate frequency signal (IF). The second IF signal is passed through a limiter and output as the frequency converted signal.

Abstract: Transmit and receive programmable band select/transfer modules provide low cost means for selecting and translating spectral segments within sectors of a LMDS basestation. The modules are programmable to select spectral segments and translate the frequency of the selected segments to designated spectral positions in the sector's output signal. Each module shifts the frequency of an applied uwave signal to dispose a predetermined spectral segment about an IF frequency. The predetermined spectral segment is then selected using a fixed frequency filter at the IF frequency. The spectral segment has one of several bandwidths, selected by one of multiple fixed frequency filters in the modules. The module translates the frequency of the filtered spectral segment to dispose the selected spectral segment about an output frequency to provide the sector's output signal. An optional pilot signal or service channel may be summed with the filtered spectral segment prior to the frequency translation.

Abstract: A tuner is used in common for both terrestrial and satellite television reception. A second mixing stage is switched as a mixer for signal conversion into a second intermediate frequency during terrestrial television reception and is switched as a component of a FM-PLL demodulator during satellite television reception. The tuner is particularly suitable for television receivers and video recorders which receive signals from both a terrestrial antenna/signal source and from a satellite antenna/signal source.

Abstract: A low power zero-IF selective call receiver has a local oscillator (106) that generates an injection signal for a first mixer (104) and a pair of quadrature phase related injection signals (122, 124) for a pair of second mixers (112, 114). The first mixer converts the received carrier signal (102) to an intermediate signal (108). A digital phase shifter/divider (116) coupled to the local oscillator (106) generates the pair of quadrature phase related injection signals (122, 124) at the frequency of the intermediate signal (108) which also equals the frequency of the local oscillator (106) divided by an integer greater then 1. The pair of second mixers (112, 114) coupled to the digital phase shifter/divider (116) converts the in and quadrature phase components (122, 124) of the intermediate signal (108) to respective in and quadrature phase baseband signals (126, 128).

Abstract: A double super-heterodyne receiver has a high-frequency input circuit that includes a high-frequency amplifying device, a low-pass filter and a high-pass filter used for obtaining bandpass characteristics for the receiving band. A switching device for changing the cut-off frequency of, at least, the low-pass filter is further provided for the high-frequency input circuit. The switching device is controlled to be on or off in response to the receiving frequency, thereby changing the passband of the high-frequency input circuit. Image disturbance characteristics can thus be improved.

Abstract: A microwave frequency generator and method of generating a predetermined microwave signal. The invention comprises oscillator means to generate a determinable frequency signal and means responsive to the frequency signal received from the oscillator means to generate a predetermined Intermediate Frequency (IF) signal. The invention further includes means to generate a determinable ultrahigh frequency (UHF) signal, along with means responsive to the IF signal and to a UHF signal to generate a resultant frequency signal. Means responsive to the resultant frequency and to the predetermined frequency signal generated by the oscillator means are further provided to generate the desired predetermined microwave frequency signal.

Abstract: An apparatus for the error free transmission of PCM/FM telemetry data. The pparatus comprises a first mixer for receiving an RF signal which has a first frequency and which is the carrier for the PCM/FM telemetry data. A variable frequency oscillator provides a local oscillator signal to the first mixer which is an offset for the RF signal. The first mixer then mixes the RF signal with the local oscillator signal resulting in the RF signal having a second frequency. This RF signal is supplied to a second mixer which mixes the RF signal with a fixed frequency signal provided by a fixed frequency oscillator. The RF signal provided by the second mixer now has a third frequency and is supplied to a bandpass filter. The frequency of the local oscillator signal is adjusted so that the offset to the RF signal provided by the first mixer is approximately one half of the intermediate frequency bandwidth of the bandpass filter.

Abstract: A device for generating a first signal and a second signal in a receiver for reception of a number of radio frequency signals. The first signal is mixed in a first mixer with the received radio frequency signals in order to generate an intermediate frequency signal which is subsequently mixed with the second signal in a second mixer. A first oscillator generates a signal which, after frequency multiplication in a frequency multiplier, is the first signal, the frequency of which can be changed in a number of frequency steps. A second oscillator generates the second signal, the frequency of which also can be changed in a number of frequency steps. The magnitude of the frequency steps by which the first signal can be changed is a multiple of the frequency steps by which the second signal can be changed.

Abstract: A circuit which limits to a fixed value the amplitude of a pilot signal received along with a modulated signal, mixes the amplitude-limited pilot signal with the modulated signal, and uses the random FM noise contained in the pilot signal to cancel the random FM noise contained in the modulated signal. The desired signal to be received is selected from the input signal at the high frequency band; this output is converted to a low frequency band signal by means of a frequency converter. The extraction of the pilot signal and the cancellation of the random FM noise is performed in the low frequency band, whereby the characteristics required for the high frequency band-pass filter are relaxed.

Abstract: A radio receiver front end is disclosed that processes a multi-carrier signal with a large dynamic range. An illustrative embodiment of the present invention incorporates both feedforward and feedback mechanisms to suppress the amplitude of spurious carrier signals so as to prevent those signals from flooding the dynamic range of the mixer that mixes down the multi-carrier signal.

Abstract: A multiple conversion receiver system capable of avoiding receiver spurs by combined switching of multiple local oscillator frequencies, including combinations of high-side and low-side injection and IF shifting.