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Topic: Intermediate frequency


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In the News (Sat 20 Jul 19)

  
 Intermediate frequency FM receiver using analog oversampling to increase signal bandwidth - Patent 5483695
Frequency modulation refers to the process whereby the frequency of a carrier signal is modulated by a message signal--the amplitude of the carrier signal is intended to remain constant.
Superheterodyne FM receivers which use such high intermediate frequencies may be largely integrated in a single integrated circuit, however the signal processing involved in such receivers necessitates the use of off-chip tuned LC circuits, and ceramic or surface acoustic wave (SAW) filters in the RF, heterodyning and demodulation stages of the receiver.
As the frequency of the modulated intermediate-frequency signal is multiplied by a factor of n, the demodulated bandwidth of the message signal is thus correspondingly increased by a factor of n without requiring a change in the intermediate frequency used in the FM receiver.
www.freepatentsonline.com /5483695.html   (4518 words)

  
 Conversion   (Site not responding. Last check: 2007-11-06)
The intermediate frequency pass band of the receiver is less than that of the transmitted signal, some of the energy of which is attenuated by the receiver's circuits resulting in significant phase distortion attributable to the intermediate frequency filters.
In conversion systems, such steps have to be taken at intermediate frequencies which lead, with respect to the demodulated frequency, to greater difficulty as a function of the value of the intermediate frequency.
Frequency response of the composite input is ±1 dB from 30 Hz to 100 kHz.
www.bext.com /conversi.htm   (1474 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
The coupling of the receive signal and harmonics thereof to the VCO in intermediate frequency and direct conversion receivers may be reduced by mixing the receive signal at a mixer injection frequency, fLo, obtained from a VCO frequency that is outside the bandwidth of the receive signal or harmonics thereof, as illustrated in FIG.
The method of Claim 11, the frequency divide ratio is q > 1, mixing the received signal at a mixer injection frequency derived from a VCO frequency that is outside a bandwidth of the nth harmonic of the received signal, where the frequency divide ratio q equals the harmonic number n.
The method of Claim 22, providing the mixer injection frequency derived from a VCO frequency that is outside a bandwidth of the harmonics of the received signal by dividing a voltage controlled oscillator output by a frequency divide ratio, the harmonic of the received signal corresponding to the divide ratio of the frequency divider.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/49303.030612&ELEMENT_SET=DECL   (2574 words)

  
 RCA
Instead of relying on selecting and amplifying the signal at the incoming broadcast frequency, by means of circuits which must be adjusted to that frequency, the superheterodyne changes the broadcast frequency to a lower, fixed frequency where it can be amplified and unwanted frequencies eliminated much more efficiently.
The ease of obtaining high amplification and selectivity in an intermediate frequency amplifier is chiefly due to the relatively low frequency used and to the fact that the characteristics of such an amplifier are independent of the broadcast frequency to which the set is tuned.
Thus, if the intermediate frequency characteristic of the receiver is such that it will attenuate the higher frequency side bands of the broadcast signal, the high acoustic frequencies will be lacking in the reproduction.
www.antiqueradios.org /gazette/rca.htm   (1885 words)

  
 IDH   (Site not responding. Last check: 2007-11-06)
It is this consistency of disturbance that is at the core of the intermediate disturbance hypothesis.
An investigation into the frequency of burn regimes in tallgrass prairie experiments found that diversity was the lowest on plots that received an annual burn, and was at a maximum on plots that received an intermediate burn frequency.
The relationship between disturbance frequency and diversity was opposite to that predicted by the intermediate disturbance hypothesis.
www.headwaterstreams.com /idh.html   (2583 words)

  
 MM 0705, Lesson 7   (Site not responding. Last check: 2007-11-06)
The tank circuit at the input of the mixer is tuned to the frequency of the incoming RF signal.
For superheterodyne reception, only the sum or difference frequency is of interest, and all other frequencies in the output of the mixer must be filtered out.
Also, for the higher oscillator frequency, the percentage of frequency shift for the oscillator tuning capacitor must be smaller for the same tuning range than that of the mixer and RF capacitors.
www.oldradioz.com /electronic_course/ch7.htm   (6556 words)

  
 Introduction to the Superheterodyne Receiver
An intermediate frequency which is close to some part of the tuning range of the receiver is avoided as this leads to instability when the receiver is tuned near thefrequency of the IF channel.
The first Intermediate frequency is then mixed at J with the output of the bandpass filter H to produce a difference output frequency tuned by second IF stage K, within the frequency range of 3 to 2 MHz.
The output frequency range of mixer C is 14.330 to 14.830 MHz and this is mixed further in mixer B, with either the 10 MHz reference frequency or its second harmonic (20 MHz), to obtain various output frequencies for the different bands as shown on the diagram.
users.tpg.com.au /users/ldbutler/Superhet.htm   (6341 words)

  
 Intermediate Frequency System   (Site not responding. Last check: 2007-11-06)
Receivers on the 100m telescope are operated in the frequency range 400 MHz to 86 GHz with instantaneous bandwidths from a few MHz up to 2 GHz.
Such input frequencies are translated by one or more oscillators into the IF range.
The frequency dependent attenuation of these cables is compensated by correction filters having an opposite characteristic.
www.mpifr-bonn.mpg.de /div/electronic/if.html   (278 words)

  
 Tuner patent invention   (Site not responding. Last check: 2007-11-06)
The common signal is supplied to a single down converter 6, which converts the common signal to a lower frequency range and, in particular, converts each of the channels A and B to respective different second intermediate frequencies.
The down converter 6 is connected to an output 12 for supplying the channels A and B at their respective second intermediate frequencies for further processing, which ultimately results in the individual channels being separated from each other and demodulated.
The common signal carrying the two channels A and B at the different second intermediate frequencies is supplied to the inputs of filters 7A and 7B, which are of the same type as the filters shown in FIG.
www.freshpatents.com /Tuner-dt20041014ptan20040204034.php   (4550 words)

  
 Microcomputer-controlled one-step-back automatic frequency control tuning system - United States Patent 4,280,140
Automatic frequency control (AFC) systems are, in general, well known in the art and typically involve heterodyning the transmitted signals picked up by the receiver's tuner with locally generated oscillator signals and producing intermediate frequency (IF) signals for processing.
The frequency offset in television video games is generally attributed to the wider tolerances in terms of nominal operating frequency, frequency stability, etc., of the oscillators utilized.
The frequency division chain from the local oscillator in the tuner 21 to the phase comparator 38 is composed of a fixed divide by 256 prescaler 48, a fixed divide by four in the PLL chip and a ten stage variable divider or counter 36 in the PLL.
xrint.com /patents/us/4280140   (9336 words)

  
 [No title]   (Site not responding. Last check: 2007-11-06)
Such a computation of an approximation of the magnitude of the received vector, used as a received signal strength indicator signal in the intermediate frequency domain, is complex.
If the transceiver 1 is a zero intermediate frequency radio device operating in the ISM band, and receiving and transmitting in channel one of the ISM band, the frequency synthesizer 15 is tuned to 2.4 GHz.
If the transceiver 1 is a low intermediate frequency radio device operating in the same band and channel, the frequency synthesizer is tuned to a slightly different frequency than 2.4 GHz.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/47154.010628&ELEMENT_SET=DECL   (2352 words)

  
 Intermediate frequency - Wikipedia, the free encyclopedia
An intermediate frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception.
It is the beat frequency between the signal and the local oscillator in a radio detection system.
Widely used IF frequencies are 10.7MHz (FM Radio), 455kHz (AM Radio) and 44KHz (television reception).
en.wikipedia.org /wiki/Intermediate_frequency   (145 words)

  
 5.7 GHz ATV Converter
A frequency of 423 MHz was selected, which does not cause harmonics either in the reception range or in the intermediate frequency range.
For the intermediate frequency, reactive impedances arise on both sides of the diode which, together with the conduction component Lt 1 (approximately lambda/4 for 5.7 GHz) and the input circuit of IC 3 (stub 1, C 10) form a low-pass filter for the intermediate frequency.
IC 3 acts merely as an intermediate frequency amplifier, through which the LO is additionally attenuated using stub 1.
www.vhfcomm.co.uk /atv-conv.htm   (832 words)

  
 Digital automatic frequency control with tracking - United States Patent 4,498,191
The microprocessor is first operated in a frequency search mode to increase or decrease the frequency of the VCO in predetermined frequency increments depending on the logic state of the output of the comparator (15).
The tuner intermediate frequency is sampled to provide information to the microprocessor as to whether the tuner local oscillator needs to be adjusted to accommodate a frequency offset in the received signal.
In the vicinity of the correct frequency, the AFC output may be regarded as being approximately linear about a reference level representing zero frequency error (45.75 MHz in the example given).
xrint.com /patents/us/4498191   (4039 words)

  
 Multiband Power System Stabilizer (SimPowerSystems)
Frequencies are typically in a range of 0.2 to 0.8 Hz.
The center frequency, in hertz, and peak gain of the intermediate frequency bandpass filter.
The frequency range used to plot the frequency response of the stabilizer.
www.weizmann.ac.il /matlab/toolbox/powersys/multibandpowersystemstabilizer.html   (1129 words)

  
 McGraw-Hill AccessScience: Intermediate-frequency amplifier
Signal frequency spectrum downconversion is achieved by multiplying the radio-frequency signal by a local oscillator signal in a circuit known as a mixer.
A variable local oscillator is used in the receiver to hold the difference-signal center frequency constant as the receiver is tuned.
The constant frequency of the downconverted signal is called the intermediate frequency (IF), and it is this signal that is processed by the intermediate-frequency amplifier.
www.accessscience.com /Encyclopedia/3/34/Est_349200_frameset.html?doi   (168 words)

  
 CONVERTER STAGE
Maintains a constant frequency difference between the locally generated frequency and any signal to which the receiver is tuned.
Maintains a constant frequency difference between the locally generated frequency and any signal to which the receiver is tuned - The local oscillator must always maintain a frequency difference between its own frequency and the incoming signal equal to the I-F (intermediate frequency).
Since the intermediate frequency stages are fixed tuned, the oscillator and tuning to the input of the mixer stage must track properly so that the two circuits are always 455 kHz apart over the entire tuning range.
www.radioremembered.org /convtr.htm   (1321 words)

  
 HDTV
A band pass filter having a flatness in pass band and a small deviation of group delay which will prevent the demodulation of a high definition TV signal from degradation is used a first intermediate frequency filter 11.
An SAW filter is used as a second intermediate frequency filter 16.
The third mixer 28 for converting a second intermediate frequency signal to a third intermediate frequency signal in frequency is installed and the frequency of the third intermediate frequency signal to be converted is set to a value lower than the frequency of the second intermediate frequency signal.
www.hdtvmagazine.com /archives/patent.html   (290 words)

  
 Department of Electrical Engineering
The main characteristics that needed to be obtained from the mixer simulation were the frequency content of the output and the voltage level of the intermediate-frequency output component relative to the RF input.
Using 1425 kHz as the resonant frequency and choosing an inductor of 100 microhenries, the equivalent capacitance was calculated from equation (2) to be 124.7 pF.
  The frequency of the output was measured to be 467 kHz, with a peak-to-peak voltage of 7.32 Volts.
www.eng.usf.edu /~baylis/EEL4936FinalReport1.htm   (5383 words)

  
 Future Tasks   (Site not responding. Last check: 2007-11-06)
The tests that will be performed on the system include: Signal to noise ratio, intermediate frequency power level, return loss, intermediate frequency amplitude response, group delay, intermediate frequency differential phase and gain, central frequency and deviation sensitivity, baseband linearity, group delay, and finally baseband differential gain and phase.
The intermediate frequency power level test is done to ensure that the output power of all the channels is correct within 1dB.
The frequency spectrometer can be used to test how much the microwave signal deviates from it's central frequency of 8394.63 MHz, therefore giving the exact bandwidth of the signal.
www.ee.unb.ca /thesis97/ee4000e/future.htm   (537 words)

  
 Mixer 2x2 Spurious Response and IP2 Relationship - Maxim/Dallas
This process is known as down-conversion utilizing the difference term between the mixer's RF input and local oscillator input (LO) for low-side injection (LO frequency < RF frequency) or the difference term between the mixer's LO and RF for high-side injection.
is the intermediate frequency at the mixer's output port, f
When specifying the mixer's IP2 or 2x2 performance, it is assumed that only the fundamental RF and LO frequencies are applied to the mixer ports and that the harmonic distortion is created in the mixer alone.
www.maxim-ic.com /appnotes.cfm?an_pk=1838   (1607 words)

  
 PHILCORADIO.COM Tech Section - Model 90 Intermediate Frequency
When it comes time to perform an alignment on a Model 90 receiver, there has been a great deal of confusion over the years concerning the proper intermediate frequency to be used.
The front end of both receivers are virtually identical, as is the IF circuitry, save for the added automatic volume control (AVC) in the second version and the lack of a "normal-maximum" switch in the second version.
It is known that the first version uses an intermediate frequency (IF) of 175 kc.
www.philcoradio.com /tech/90if.htm   (335 words)

  
 Satellite Uplink and Downlink
Digital data is sent to the modulator which takes the data and converts it into a modulated signal in the Intermediate Frequency range (70-140 Mhz).
The Intermediate Frequency is piped to an "up converter" (usually via shielded coaxial cable) which mixes the intermediate frequency with a higher frequency to produce a final frequency which carries the modulated data.
The intermediate frequency is fed to the demodulator and converted into a data signal
www.inetdaemon.com /tutorials/telecom/satellite/uplink_chain.shtml   (384 words)

  
 Selection and Operation of Wireless Microphone Systems - page 6
to combine signals of various frequency in a manner that produces additional signals at frequencies which are sums and differences of the original frequencies
intermediate frequency, a lower radio frequency (typically 10.7 MHz) found in the middle stages of a receiver
residual output from crystal-controlled transmitters occurring at frequencies that are offset from the operating frequency by multiples of the crystal base frequency
www.shure.com /booklets/wireless/wireless_page6.html   (1232 words)

  
 RMCybernetics - Unexplained Phenomenon   (Site not responding. Last check: 2007-11-06)
Therefore, finding the resonance frequency (or harmonics) of the molecular bonds would be indeed a much more efficient way of changing the state of matter.
The anomalous melting of metal without any evidence of heating, burning or scorching of the adjacent materials (usually wood) can be easily explained if one considers the external high voltage intermediate frequency source to be resonant with the molecular structure of the metal.
However, the zone in which the interferences take place is stressed by hundreds of kilovolts oscillating at the intermediate resonant frequency.
www.rmcybernetics.com /science/physics/unexplained.htm   (1393 words)

  
 Intermediate Frequency 140 MHz IF to L Band Up Converter
The PUL 140D is an ultra-stable frequency upconverter that is capable of translating digital 140 MHz IF signals to any customer-specified L band channel.
Based on Quintech's very popular fixed channel converters, it features highly improved phase noise and stability performance exceeding the IESS 308/309 standard and is suitable for all current high speed data transmission rates and advanced digital modulation schemes.
Note: The channel frequency is factory preset to the customer-specified L-band channel.
www.quintechelectronics.com /pul140d-if-140-upconverter.php   (246 words)

  
 Image frequency - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-11-06)
Image frequency: In radio reception using heterodyning in the tuning process, an undesired input frequency that is capable of producing the same intermediate frequency (IF) that the desired input frequency produces.
The term image arises from the mirror-like symmetry of signal and image frequencies about the beating-oscillator frequency.
This page was last modified 13:37, 15 March 2006.
en.wikipedia.org /wiki/Image_frequency   (84 words)

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