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Topic: Frequency synthesiser

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	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		A frequency synthesizer is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator.
		It compares the frequencies of two signals and produces an error signal which is proportional to the difference between the input frequencies.
		The key to the ability of a frequency synthesizer to generate multiple frequencies is the divider placed between the output and the feedback input.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Frequency_synthesiser (1135 words)

	Fractional-division frequency synthesizer for digital angle-modulation - Patent 4492936
		A frequency synthesizer of the fractional-division type is already well-known and has the intended function of delivering an output signal of the form F.sub.S =(N+k)F.sub.R where N is the integral part of a number N+k and F.sub.R is the frequency of a reference signal.
		When a frequency synthesizer of this type is intended to be associated with a digital-signal modulator for delivering a signal which is angle-modulated by digital data, it is a known practice to place the modulator in the control loop or at the output of the frequency synthesizer.
		In the case of the frequency synthesizer according to the invention, the number G is derived from the sum of a number g and of a number dg, said sum being formed by an adder 80.
	www.freepatentsonline.com /4492936.html (2311 words)

	Frequency Synthesiser (Site not responding. Last check: )
		A frequency synthesiser is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator.
		It compares the frequencies of two signals and produces an error signal which is proportional to the difference between the input frequencies.
		The key to the ability of a frequency synthesiser to generate multiple frequencies is the divider placed between the output and the feedback input.
	www.purpleuniverse.com /true_associate-Frequency_Synthesiser.html (969 words)

	Direct digital frequency synthesizer invention
		The frequency synthesiser according to claim 4, wherein the noise signal bandpass-filtered in the low-frequency range is generated by a noise generator, which is controlled with a frequency-divided reference clock pulse obtained from a common reference clock pulse by an intermediate connection of a frequency divider.
		The frequency synthesiser according to claim 3, wherein the anti-aliasing low-pass filter is followed by an analog high-pass filter for suppression of the noise signal bandpass-filtered in the low-frequency range in an output signal of the anti-aliasing low-pass filter.
		The frequency synthesiser according to claim 12, wherein the coarse-grid mixed-frequency signal supplied to the mixer of the phase-locking loop is generated by a second phase-locking loop or by conversion from the common reference frequency.
	www.freshpatents.com /Direct-digital-frequency-synthesizer-dt20060824ptan20060186930.php?type=claims (494 words)

	Frequency synthesiser - Education - Information - Educational Resources - Encyclopedia - Music
		A frequency synthesiser is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator.
		Before the invention of the frequency synthesiser, radio transmitters and receivers had to employ a separate crystal for each channel that the device could operate on.
		The key to the ability of a frequency synthesiser to generate multiple frequencies is the divider placed between the output and the feedback input.
	www.music.us /education/F/Frequency-synthesiser.htm (1163 words)

	Low-noise frequency synthesizer
		A frequency synthesizer (100) is utilized for producing an output signal (124) which is phase locked to a reference signal (110) operating at a reference frequency.
		The frequency synthesizer comprises a main phase lock loop, including a controlled oscillator for generating the output signal operating at an output frequency determined by a filtered control signal, and a first frequency divider coupled to the controlled oscillator for frequency dividing the output signal to produce a comparison signal operating at the reference frequency.
		The frequency synthesizer 100 is used for producing an output signal 124 which is phase locked to a reference signal 110 operating at a reference frequency.
	www.devileye.net /catalog/low-noise_frequency_synthesizer.html (2663 words)

	[No title] (Site not responding. Last check: )
		Before the invention of the frequency synthesiser, radio transmitters and receivers had to employ a separate crystal for each channel that the device could operate on.
		In practice a frequency synthesiser cannot operate over a very wide range of frequencies, because the comparator will have a limited bandwidth and may suffer from aliasing problems.
		However, in most systems where a synthesiser is used, we are not after a huge range, but rather a finite number over some defined range, such as a number of radio channels in a specific band.
	www.wikiwhat.com /encyclopedia/f/fr/frequency_synthesiser.html (916 words)

	Frequency synthesiser - TvWiki, the free encyclopedia (Site not responding. Last check: )
		A frequency synthesizer is an electronic system for generating any of a range of frequencies from a single fixed timebase or oscillator.
		Synthesizers used in commercial radio receivers are largely based on phase-locked loops or PLLs.
		In practice this type of frequency synthesiser cannot operate over a very wide range of frequencies, because the comparator will have a limited bandwidth and may suffer from aliasing problems.
	www.tvwiki.tv /wiki/Frequency_synthesiser (1152 words)

	WBFM TX V7 by Harry Lythall
		If you are not using synthesiser control and you want to add better frequency stability then the zener diode and resistor drawn in red must be fitted.
		If you are not too worried about long-term frequency stability, or you are using a regulated supply, then fit the 100K resistor (R1) and skip the zener diode.
		With a "Dual Modulus" synthesiser, such as the MC145152-2, then the V7b will form a dual modulus synthesiser and can be controlled in steps of typically 5KHz.
	web.telia.com /~u85920178/tx/v7b_proj.htm (1300 words)

	FREQUENCY SYNTHESIZER APPARATUS (US3694766)
		The frequency of the only output signal from the filter is equal to the same particular harmonic to which the phase-locked loop is locked times the difference in frequency between the reference frequency and the displaced reference frequency.
		Since the difference between the frequencies is a known, fixed value, the signal from the filter is thus a precise measure of the particular harmonic of the reference frequency being produced by the phase-locked loop.
		The output frequency of the filter may be counted and compared with a preset count representing the value of a predetermined harmonic of the reference frequency to which it is desired to tune the phase-locked loop.
	www.delphion.com /details?pn10=US03694766 (523 words)

	Synthesizer
		The Moog synthesizer even spawned a subculture of record producers who made novelty "Moog" recordings, depending on the odd new sounds made by their synthesizers (which were not always made by Moog) to draw attention and sales.
		One kind of synthesizer starts with a binary digital recording of an existing sound, which is then replayed at a range of pitches.
		Digital synthesizers generate a digital sample, corresponding to a sound pressure, at a given sampling frequency (typically 44100 samples per second).
	www.mp3.fm /Synthesizer.htm (2737 words)

	SIMPLE TEST GEAR FOR THE MICROWAVER
		Frequently available at surplus sales at prices between £50 and £135 depending on the RF head.
		Heads for higher frequencies and power inputs are available but quite difficult and expensive to obtain.
		It is a most useful item to establish a standard for other test equipment, such as the frequency counter.
	www.qsl.net /g3pho/test.htm (1282 words)

	FS1R - Download - Yamahasynth.com
		For example when using a synthesiser to simulate an actual sound, it is often the case that the simulation is quite realistic in a certain pitch range and quite unrealistic in other pitch ranges.
		Synthesiser users know that the pitch can be changed by modulating the pitch of an oscillator in various ways, but if there is only one oscillator, it is normally possible to obtain only one pitch at any moment.
		This means that you might select the formant waveform for several operators, set each operator to produce a male or female vocal sound, and control their respective formants independently to produce the sound of a human chorus, and not have to rely on effect processors to produce the impression of a greater number of singers.
	www.yamahasynth.com /download/fs1r/s_guide.htm (3830 words)

	debugging a PLL frequency synthesizer
		At frequencies within the PLL bandwidth, the phase noise at a synthesizer output is dominated by the phase detector's phase noise.
		Meanwhile, at frequencies outside of the PLL bandwidth, the output phase noise is due to VCO phase noise.
		This lower frequency sets the comparison rate for the detector and establishes the smallest frequency step possible by incrementing the feedback divider by “1.” This becomes the frequency resolution of the synthesizer, or frequency step size, which should be equal to or smaller than the channel spacing of the radio system being designed.
	rfdesign.com /mag/radio_debug_pll_frequency (3066 words)

	FREQUENCY SYNTHESIZER
		Therefore, both frequency and phase are made the same, i.e., fosc=fref and θosc=θref, such that the phase and frequency of the VCO and the reference signal are in a locked state.
		When the PLL is not in the phase-locked state, if the frequency of the input signal, fref, slowly approaches the free running frequency of the VCO, the frequency range in which the input signal becomes phase-locked is called the lock-in range or capture range.
		The frequency division ratio is determined from the reference frequency and the desired frequency according to equation 5.
	www.geocities.com /koubelis (3468 words)

	Digital phase comparison apparatus
		PLL's are used, for example, to lock the frequency of an oscillator on to an input frequency or a multiple or sub-multiple thereof.
		In this case it is assumed that the frequency change is such as to cause the comparator to operate on one of the flanking portions of the characteristic curve which has a zero slope.
		Logic circuit 31 also includes a frequency difference detector which operates to provide a signal at its output 42 or 43 respectively, according to whether the frequency of a signal at input 11 is less or greater than the frequency of the signal at input 21.
	www.devileye.net /catalog/digital_phase_comparison.html (6500 words)

	pc_tech
		Frequency Modulation Synthesis: an outdated technique for synthesising music reproduction but still widely supported to provide compatibility with older games software.
		Roland GS Roland General Synthesiser and General MIDI are two overlapping specifications for defining the standard sets of MIDI sounds that are associated with specific commands.
		The sampling frequency should be at least twice that of the analogue frequency being digitised.
	www.aurora.komvux.norrkoping.se /Pedagogical_Web/Web_course/UTB1/pc_tech.htm (1354 words)

	VK3BIZ Home Page
		The solution I thought was to make a frequency synthesiser for it using some old synthesiser chips I had in the junk box.
		If we assume a 25KHz channel spacing, the synthesiser reference frequency can be programmed to be 1/9th the channel spacing for receive or 1/8th the channel spacing for transmit, which gives a reference frequency around 3KHz.
		The upper frequency limit is determined by the drive level into the synthesiser chip, but I am not sure at this stage what the drive level out of the VCO will be.
	members.optusnet.com.au /vk3biz/IC215/IC215PLL.html (1289 words)

	Fast switching frequency synthesizer (US4800341)
		A synthesizer produces step frequencies by multiplying the frequency of a reference oscillator and stimulating an SRD comb frequency generator, then adding or subtracting a reference frequency.
		Frequency dividers, which would result in noisy final outputs, are not employed.
		Instead, the frequency of a reference signal is multiplied up in a narrowband channel to serve as a local oscillator, and the VCO signal frequency is reduced by heterodyning it down from its ultra-high frequency.
	www.delphion.com /details?pn=US04800341__ (442 words)

	Accurate Simulation of an X-band Frequency Synthesizer \| September 11, ...
		In the simulation, the reference spurs and their effect on the noise performance of the PLL frequency synthesizer are also included.
		Frequency multipliers and dividers are now available to simplify the design and implementation of X- and Ku-band synthesizers.
		The PLL consists of a high stability crystal reference oscillator, a frequency synthesizer, a voltage-controlled oscillator and a passive loop filter.
	www.mwjournal.com /Journal/article.asp?HH_ID=AR_1532 (565 words)

	Radio-Electronics.Com :: PLL Frequency Synthesizer Tutorial
		Not only do frequency synthesizers enable receivers to have the same stability as the quartz reference, but they also enable many other facilities to be introduced because they can easily be controlled by a microprocessor.
		Most synthesizers need to be able to step in much smaller increments if they are to be of any use.
		This is usually accomplished by running the reference oscillator at a frequency of a megahertz or so, and then dividing this signal down to the required frequency using a fixed divider.
	www.radio-electronics.com /info/receivers/synth_basics/synth_basics.php (1606 words)

	Frequency Synthesiser - Direct Method (Site not responding. Last check: )
		In the direct frequency synthesiser method the required carrier is obtained through a process of frequency multiplication, mixing and filtering.
		Multiplication is achieved using frequency multipliers or harmonic generators and division relies on digital techniques using re-generative dividers or bi-stable filters.
		While the process has the advantage that the stability and accuracy of the output frequency is set by the reference crystal oscillator source, the method has major disadvantages in that the mixing process generates spurious frequencies and requires a number of costly filters.
	www.argospress.com /Resources/transmitters-receivers/frequesinthedirectmethod.htm (176 words)

	A Practical Design of a Low Phase Noise Airborne X-band Frequency Synthesizer \| October 12, ...
		Frequency synthesizers have been well studied, but difficult problems sometimes arise in their practical implementations.
		The phase noise is —80 dBc/Hz at 100 Hz and —97 dBc/Hz at 10 to 600 kHz frequency offset.
		There are two different ways to design a synthesizer—use a VCO at half the output frequency to produce the input signal to the PLL and then double it or use a VCO at the output frequency and then divide by 2 to produce the input signal to the PLL.
	www.mwjournal.com /Journal/article.asp?HH_ID=AR_3450 (527 words)

	voltage controlled oscillators
		This is to be part of a frequency synthesiser, although a vco isn't always associated with a frequency synthesiser.
		In this application of a frequency synthesiser they are unlikely to be necessary.
		For a frequency synthesiser the tuning voltage is derived from the low pass filter of the PLL and you don't need to worry about it.
	my.integritynet.com.au /purdic/voltage-controlled-oscillators.htm (1704 words)

	PC-Based Synthesizer
		Because PLL circuits are highly sensitive to supply-voltage variations, it is advisable to use a separate 5-volt regulator for the 4046 to reduce "chirp" on the signal.
		Here is a step-by step example of how an actual output frequency is synthesized, assuming that you have connected the PLL circuit of Figure 2 to the PC speaker output and set the hardware divider to a fixed ratio N = 128.
		The resulting sound frequency is actually 1471.24 Hz, and the output of the PLL synthesizer is this frequency multiplied by 128 or 188,318.7 Hz.
	www.mlecmn.net /~lyle/pc-syn/pc-syn.htm (1916 words)

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