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Topic: Double sideband

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In the News (Thu 23 May 19)

  Sideband - Wikipedia, the free encyclopedia
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing energy as a result of the modulation process.
In this case the receiver locally regenerates the subcarrier by doubling a special 19 kHz pilot tone, but in other DSB-SC systems the carrier may be regenerated directly from the sidebands by a Costas loop or squaring loop.
Sidebands are also what cause interference to adjacent channels, and therefore they must be suppressed by filters, either before or after modulation (or often both).
en.wikipedia.org /wiki/Sideband   (470 words)

 Single-sideband modulation - Wikipedia, the free encyclopedia
Since the final RF amplification is now concentrated in a single sideband, the effective power output is greater than in normal AM (the carrier and redundant sideband account for well over half of the power output of an AM transmitter).
To recover the original signal from the IF SSB signal, the single sideband must be frequency-shifted down to its original range of baseband frequencies, by using a product detector which mixes it with the output of a beat frequency oscillator (BFO).
A vestigial sideband (in radio communication) is a sideband that has been only partly cut off or suppressed.
en.wikipedia.org /wiki/Single-sideband_modulation   (1357 words)

 MMA Memo 168: Relative Sensitivities of Single and Double Sideband Receivers for the MMA
With a double sideband system both sidebands may be used, as in a continuum observation, or just one sideband, as in a spectral line observation where the lines of interest occur only in one sideband.
A double sideband mixer receiver can be made into a single sideband receiver by filtering out the unwanted sideband ahead of the mixer, or by using two mixers with quadrature hybrids in the signal and IF connections, as is proposed in the development by Kerr and Pan.
Where both sidebands are used, as in continuum operation, there does not seem to be such a strong case for preferring either single or double sideband when the range of conditions in the three tables is considered.
www.cv.nrao.edu /alma/almaweb/www/memos/html-memos/alma168/memo168.html   (1416 words)

 Gilbert Cells
Because the gain control is highly linear, Gilbert cells are often referred to as four-quadrant multipliers and have common applications as mixers, AGC amplifiers, amplitude modulators, double sideband (DSB) modulators, single sideband (SSB) modulators, AM detectors, SSB and DSB detectors, frequency doublers, squaring circuits, dividers, square-root circuits, and root-mean-square, r.m.s., measuring circuits.
The output waveform, vout, for the double balanced modulator is shown in figure 8.
Further deriviatives of the double balanced mixer can be used to generate only the upper, or lower, sideband during the modulation process, or can be used to mix two signal and reject either the lower, or the upper, image frequency.
members.tripod.com /michaelgellis/gilbert.html   (1360 words)

 Modulator processing for a parametric speaker system - Patent 6584205
Double sideband signal systems used with parametric arrays must always be at least the bandwidth of the signal above any audible frequency (assuming a 20 kHz bandwidth) and even more if the distortion reducing square root function is used which also demands an infinite bandwidth.
Because the lower sideband of a double sideband system must be kept from producing output in the audible range, the carrier frequency must be kept at least 20 kHz above the audible upper limit for double sideband (DSB) and at the very least twice that amount with a square rooted DSB.
A truncated double sideband (TDSB) signal may also be produced in the invention, where the lower sidebands of a double sideband (DSB) signal are sharply truncated by a filter so nearly all of the frequencies passed are above the carrier.
www.freepatentsonline.com /6584205.html   (8479 words)

 False Performance Claims
Double sideband was allowed 8-Watts output and the advertising seemed to be accurate on those units.
On the other hand, the single sideband radios were advertised as 25 Watt radios, and once again, this was the input power rating.
Yes these radios have adjustments to limit carrier power, sideband power, AM modulation, and FM deviation, but these are there to keep the radios from over modulation and proper drive levels.
cbworldinformer.com /200108/false_performance_claims.htm   (1037 words)

Double sideband channels are shown schematically in Figure
These channels are also referred to as folded passbands with the lower frequency sideband referred to as the lower sideband and the higher frequency sideband being the upper sideband.
They resemble two double sideband “subchannels”on either side of the channel central frequency (Note: “subchannels” is not a common or rigorous term and is used here for explanation only).
www2.ncdc.noaa.gov /docs/klm/html/c3/sec3-3.htm   (1504 words)

 Receiver A3 - sideband differences
In a heterodyne receiver incoming signals from the sky are combined ("mixed") with a pure local oscillator (LO) signal, the frequency of which is adjusted for the relative motion of the astronomical target and the receiver.
Thus the "signal" sideband is centered at the rest frequency, and the "image" sideband is 8 GHz either below or above the signal sideband, depending on which sideband (upper or lower respectively) is chosen as the the one containing the signal.
Receiver A3, however, does not have sideband rejection and thus is a DSB instrument by default.
www.jach.hawaii.edu /JCMT/spectral_line/Instrument_homes/RxA3i/sidebands_new.html   (625 words)

 United States Patent: 6,587,729
transmitting the double sideband output signal to a demodulator, whereby the audio signal a(t) is recovered from the double sideband output signal.
The modulation process known as suppressed carrier, produces a double sideband output=(a(t)As(f)+A).sup.1/2 sin(.omega..sub.c t), where.omega..sub.c is the carrier frequency.
The output of the balanced modulator is applied to a spherical demodulator 34, which recovers the input signal a(t) that is applied to the inner ear 35 and then to the acoustic receptors in the brain 36.
www.raven1.net /6587729.htm   (3636 words)

 Guide to Spectral Line Observing at the JCMT
The image sideband rejection is not absolute; typically it is in the range 12-14 dB, or a factor of not better than, say, 25.
Thus a 1 K line in the rejected image sideband will still appear as a 40 mK line in the spectrum of the signal sideband, and one should be aware of this potential source of confusion.
Since lines in opposite sidebands move in opposite directions as the LO changes, frequency-switching automatically identifies the sideband in which a line appears because upper and lower sideband lines have mirror-image profiles in the unprocessed data.
docs.jach.hawaii.edu /JCMT/HET/GUIDE/het_guide   (10114 words)

Because there are two pieces of sidebands; this type of AM is called double sideband (DSB) modulation.
Because there are two sidebands and each is exactly the bandwidth of the original modulating signal, as shown in Figure 4, the resultant bandwidth is twice the original modulating signal's bandwidth.
There are two sidebands and it is important to use rms voltages for computing power.
www.8vsb.com /Amplitude-Modulation.htm   (2865 words)

 Untitled Document
An inherent problem with AM or, more specifically, double - sideband full carrier (DSBFC) is the enormous amount of power containted in the carrier frequency.
Since the sidebands are the sum and difference of the carrier and modulating signals, the information must be contained in both of them.
The remaining sideband is called a single- sideband suppressed carrier (SSSC or SSB) signal.
e-learning.mfu.ac.th /mflu/1502231/main2/c1/AM_1.htm   (487 words)

 What is SSB?
As a result, the sideband located just above the carrier frequency is called the upper sideband and that which is located just below the carrier frequency is called the lower sideband.
To produce this AM signal, the transmitter is, in effect, working as three transmitters: one to produce a strong carrier for each of the sidebands, an upper sideband, and a lower sideband.
But in highly effective communications using single sideband, a single sideband signal removes the carrier and one sideband and concentrates all of its energy in one sideband.
www.sgcworld.com /whatisssbtechnote.html   (3329 words)

 Frequency Extenders for Noise Figure Meters, MT7551B   (Site not responding. Last check: 2007-10-25)
Two are double sideband converters, while the MT7550A is a single sideband converter.
Frequency conversion of broadband noise signals can be either single sideband, if one of the two RF responses is eliminated, or double sideband, if both are allowed to be mixed down to the IF.
Maury offers a selection of frequency extenders which take advantage of these conditions: cost effective, double sideband units for use over wide frequency ranges and at the higher microwave frequencies, and a single sideband extender for the lower microwave region.
www.maurymw.com /products/ncsa/nfm_freqxtdrs/mt7550x.htm   (481 words)

 A 0.8 mm SIS receiver with a #tex2html_wrap_inline2031# noise at the 30m Telescope
The single sideband receiver noise of 48 K is only three times above the quantum limit of heterodyne receiver sensitivity.
In the new receiver the upper sideband is rejected by the tuning of a single backshort in the SIS mixer.
The new receiver single sideband noise temperature is 48 K at 330 GHz while the double sideband noise is about 30 K around 320 - 340 GHz (Figs.
iram.fr /IRAMFR/ARN/jan98/node11.html   (567 words)

 12M Manual Chapter 5   (Site not responding. Last check: 2007-10-25)
The primary things to watch out for when choosing the sideband configuration for a DSB measurement is the presence of “contaminating” lines from the image sideband.
If an image line is too close to the program line in the signal sideband, a small local oscillator shift will usually cure the problem (the frequency axes run oppositely for the upper and lower sidebands).
For upper sideband operation, the signal frequency will be higher than the reference frequency, so that the emission line will appear to the right of the reference signal in spectra.
maisel.as.arizona.edu /12_obs_manual/charter_5.htm   (6891 words)

 RAND | Papers | A comparison of single-sideband, suppressed-carrier and double-sideband, full-carrier amplitude ...
In this paper, SSB and AM signals are analyzed using a wave form that can be varied in shape from a spike through a sine wave to a square wave by varying a parameter.
The average sideband powers and the peak envelope powers are then calculated and compared.
The paper shows that the ratio of average sideband power to peak envelope power for AM is more favorable than that for SSB for "squarish" modulating signals.
www.rand.org /pubs/papers/P7254   (379 words)

 amod (Communications Toolbox)
to produce the lower sideband instead of the upper sideband.
Notice that the spectrum in the left plot has two peaks; these are the lower and the upper sidebands of the modulated signal.
The two sidebands are symmetrical with respect to the 10 Hz carrier frequency,
www-rohan.sdsu.edu /doc/matlab/toolbox/comm/amod.html   (584 words)

 [No title]
] Amplitude modulation in which the modulated wave is composed of a carrier, an upper sideband whose frequency is the sum of the carrier and modulation frequencies, and a lower sideband whose frequency is the difference between the carrier and modulation frequencies.
] The transmission of a modulated carrier wave accompanied by both of the sidebands resulting from modulation; the upper sideband corresponds to the sum of the carrier and modulation frequencies, whereas the lower sideband corresponds to the difference between the carrier and modulation frequencies.
] A method of obtaining a running fix by measuring the distance a craft travels while the relative bearing (right or left) of a fixed object doubles; the distance from the object at the time of the second bearing is equal to the run between bearings, neglecting drift.
www.accessscience.com /Dictionary/D/D29/DictD29.html   (2427 words)

 Single Sideband Signal Generation - June 11th Fact-of-the-Day
A common method of generating a single-sideband (SSB) signal is to split an incoming audio intelligence signal into two signals that are identical, except for a 90-degree phase difference, and to split a constant amplitude and frequency carrier signal into two carrier signals that also have a 90-degree phase difference.
However, there is no phase difference between one of the sidebands in the two modulator outputs, but there is a 180-degree phase difference between the other sideband in the two outputs.
The two balanced modulator outputs are summed, which cancels one sideband and doubles the strength of the other, resulting in a single-sideband signal.
www.smeter.net /daily-facts/6/fact11.php   (150 words)

 Digital television receiver converting vestigial-sideband signals to double-sideband AM signals before demodulation - ...
mixing said vestigial sideband amplitude-modulation signal with a beat frequency different from the frequency of its own carrier, said beat frequency being of such value as to generate a mixing result that is translated in frequency to have its carrier at an offset frequency that is higher than zero frequency;
A problem with VSB signals with roll-off through carrier frequency is that the asymmetry of the modulation sidebands introduces jitter into carrier tracking that is done using variants of the well-known Costas loop.
A final I-F signal with the carrier of above a lower sideband is the result of a downconversion in which a very-high-frequency (VHF) intermediate-frequency signal is heterodyned with local oscillations of a VHF frequency above the VHF I-F signal frequency band.
www.freepatentsonline.com /6771707.html   (6825 words)

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