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Topic: Adjacent channel

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In the News (Mon 24 Jun 19)

  Adjacent channel - Wikipedia, the free encyclopedia
In broadcasting an adjacent channel is an AM, FM, or TV channel that is next to another channel.
First-adjacent is immediately next to another channel, second-adjacent is two channels away, and so forth.
Information on adjacent channels is used in keeping stations from interfering with one another.
en.wikipedia.org /wiki/Adjacent_channel   (73 words)

 NTIA TR-97-343, Assessment of Compatibility Between 25 and 12.5 kHz Channelized Marine VHF Radios
Channel plans and modulation schemes for both new and existing transceivers must be interoperable and capable of immediately participating in the VHF maritime distress and safety system if narrowbanding is implemented.
The power of the adjacent transmitters was 25 watts and three cases of antenna heights were considered: 3 meters, 3 and 10 meters, and 10 meters.
Adjacent channel separation distances were also calculated for a narrowband receiver versus a wideband transmitter off-tuned by 12.5 kHz.
www.ntia.doc.gov /osmhome/reports/tr97343/tr97343.html   (5621 words)

 [No title]   (Site not responding. Last check: 2007-10-22)
Blocks A and B consist of 10 non-overlapping channels among channels 1 to 20 and Blocks C and D consist of 10 non-overlapping channels among channels 21 to 40.
Blocks A, B, C and D consist of 5 non-overlapping channels among channels 1 to 10, 11 to 20, 21 to 30 and 21 to 40 respectively.
Summary In considering the characteristics of each channel raster and from examination of the results of the theoretical study, the advantages and disadvantages of each channel raster are as follows.
www.itu.int /itudoc/itu-r/archives/irg-gte/gte-3/7_ww6.doc   (2409 words)

 United States Patent: 6,671,338
Accordingly, efficiencies in bandwidth may be realized using techniques such as crowding of adjacent channels, frequency re-use, and increasing of data rates, generally resulting in an increased amount of data traveling through the limited amount of available bandwidth.
As the channel spacing is increased, the magnitude of the impulse response decreases but its duration is increased, resulting in an equivalent channel with larger memory span.
In order to prevent the synchronizing sequence from being obscured by the adjacent channels, a system level mechanism is needed to ensure that only one user is transmitting during its known symbol period.
www.ece.osu.edu /~helgamal/patent2.html   (5553 words)

 PSK Modulator with reduced adjacent channel interference - Patent 4261053
The output of the bit separation and stretching circuit 11 is an I and Q channel, each of which carry digital signal streams whose bit rate is 1/2 the original bit rate of the modulating signal, and in which successive bits from the modulating signal source 10 appear on separate I and Q channels.
In order to maintain the bit error rate of the transmission channel at acceptable levels, account must be taken of power reduction on the up-link due to rain attenuation (A.sub.u) on the reference channel when similar attenuation is not found in the adjacent channels from stations 1 and 3.
This circumstance increases the effect of adjacent channel interference, since the signals contributing to that interference are undiminished whereas the reference signal has been reduced by the rain attenuation.
www.freepatentsonline.com /4261053.html   (3633 words)

 MobileWorld's Glossary
Adjacent channel interference - Refers to interference caused by the energy from a transmitting channel spilling over into an adjacent channel.
The channels are relatively narrow, usually 30 KHz or less and are defined as either transmit or receive channels.
Idle Channel - A channel that is assigned to a base station use but is not currently in service (being used).
www.mobileworld.org /glossary.html   (8330 words)

 BROADCASTPAPERS.COM   (Site not responding. Last check: 2007-10-22)
The pass and stop band requirements of the channel combiner then become critical, and it is difficult to devise a design which adequately preserves the quality of the transmitted signals.
For the particular case of contiguous adjacent channels there is a frequency F which may be regarded as belonging to both channels - it is the top band edge of the lower channel and the bottom band edge of the upper channel.
It follows that all channel combiners must exhibit some type of filtering characteristic through the input channels, and the question becomes one of optimising that filter characteristic for adjacent channels.
www.broadcastpapers.com /tvtran/combining-print.htm   (2364 words)

 TVTechnology - RF Technology
The viewer noticing the adjacent channel interference thought it might be caused by out-of-channel energy in the station's DTV transmitter or overload in his TVset.
In the adjacent channel interference case, the ratio was 21.5 dB.
I don't have the coordinates for the location of the person reporting the adjacent channel DTV interference, but knowing the market I would guess he was close to mountaintop transmitter sites next to the city.
www.tvtechnology.com /features/On-RF/f_rf_technology.shtml   (1717 words)

This seems appropriate because the second adjacent channel protection ratios for both of these receiver types are exactly the same, and the third adjacent channel protection ratios are only 1.3 dB apart.
In these tests, the receiver that had the worst second adjacent channel performance was different from the one with the worst third adjacent channel performance.
The worst case second adjacent channel ratio was +3.2 dB, and the worst case third adjacent channel ratio was -9.7 dB.
www.nab.org /Newsroom/Issues/lpfm/Interference_report.asp   (2334 words)

 NTIA TR-97-343, Appendix A
The marine VHF radios (both 25 and 12.5 kHz channelized units) were tested for susceptibility to adjacent channel interference by using either 25 or 12.5 kHz channelized marine radios as interfering transmitters.
The results of adjacent signal interference tests for the 12.5 kHz mobile unit on a duplex channel versus a 25 kHz interferer are contained in Table A-8.
The marine VHF radios (both 25 and 12.5 kHz channelized units) were tested for susceptibility to adjacent channel interference for the radiated tests by using either 25 or 12.5 kHz channelized marine radios as interfering transmitters.
www.ntia.doc.gov /osmhome/reports/tr97343/tr97343a.html   (2635 words)

 adjacent channel interference   (Site not responding. Last check: 2007-10-22)
Adjacent channel interference can be drastically reduced if stations, operating on adjacent ENG and STL channels, limit unusable high frequencies.
Adjacent channel selectivity in most ENG receivers is only about 10 to 13 db.
Both are on adjacent 2 Ghz channels, close to the same compass bearing, and shoot back to a common receive site on a downtown building.
www.tvtower.com /notes_on_reducing_adjacent_chann.htm   (465 words)

 United States Patent: 6,521,958   (Site not responding. Last check: 2007-10-22)
The circuit switch of claim 1, wherein the second voltage threshold region (Vt2) in the channel is adjacent the source region, the first voltage threshold region (Vt1) in the channel is adjacent the drain region wherein the Vt2 has a higher voltage threshold than the Vt1.
The Vt2 is adjacent to the source region and Vt1 is adjacent to the drain region.
A gate 108 is separated from the channel region 108 by a gate oxide 110.
web.engr.oregonstate.edu /~flf/6521958.html   (8283 words)

 Acromag   (Site not responding. Last check: 2007-10-22)
When a radio can be set to operate at multiple frequency channels, there will be two adjacent channels, one on each side of the selected channel.
The adjacent channel rejection is the ability of the receiver to operate on the selected channel when a stronger signal is present on an adjacent channel.
It is measured as the highest ratio of the signal level on the adjacent channel to the signal being received on the selected channel.
www.acromag.com /glossary.cfm   (1539 words)

 Agilent | Wireless |  Wireless Dictionary   (Site not responding. Last check: 2007-10-22)
ACPR is usually defined as the ratio of the average power in the adjacent frequency channel (or offset) to the average power in the transmitted frequency channel.
ACS is defined as the ratio of the receiver filter attenuation on the assigned channel frequency to the receiver filter attenuation on the adjacent channel frequency.
The amount of adjacent channel interference a receiver sees is a function of transmitter and receiver filter characteristics and the number of transmitters operating in the area.
wireless.agilent.com /dictionary/a.html   (1161 words)

 - Adjacent Channel Interference   (Site not responding. Last check: 2007-10-22)
Adjacent channel interference is similar to co-channel cellular interference, causing a lower level of interference.
In the case of ReCC Adjacent Channel Interference, it is due to another mobile transmitting on an adjacent frequency to another cell site.
Adjacent Channel Interference is at it's worst when the interfering mobile has the same SAT tone as the originating mobile.
www.asteq.com /articles/adjclint.htm   (162 words)

 Sex, Drugs & Unix
While the channels don't overlap, the receivers don't have enough adjacent channel rejection (ACR) to deal with a strong (i.e.
The AP in the ajointing cube, running on an adjacent channel attempting to decode a packet at 54Mbps has an ACR of -1dB.
That -50dBm signal from the adjacent AP probably set CCA on all the APs around it (at least those operating on adjacent channels.) In this case, the second AP won't send its packet until the protocol allows it to do so.
www.smallworks.com /archives/00000087.htm   (982 words)

 Adjacent Channel   (Site not responding. Last check: 2007-10-22)
All of the UHF channels work perfectly; (the UHF antenna is one of my prototypes).
There are adjacent channel analog digital signals on UHF in Chicago.
The DTV tuner was confused by the adjacent analog channel signal and it could not decode the digital signal.
www.dtvconsultants.com /adjasent_channel.htm   (321 words)

 Glossary A to F
Adjacent channel interference  -  When the station you want is not receivable because of a much more powerful station in the next channel above or below, you have adjacent channel interference.
When a signal is 10 to 15 times more powerful than that of an adjacent channel station, most receivers become unable to receive the weaker station.
When adjacent channel stations broadcast from the same tower or adjacent towers they must have an agreement that neither will exceed 10 times the other’s power.
www.hdtvprimer.com /ANTENNAS/glossaryA.html   (4749 words)

The left-hand column lists the required minimum separation to protect other stations and the right-hand column lists (for informational purposes only) the minimum distance necessary for the LPFM station to receive no interference from other stations assumed to operating at the maximum permitted facilities for the station class.
For second- and third-adjacent channels and IF channels, the required minimum distance separation is sufficient to avoid interference received from other stations.
Channel ---------------------------------------------------------- channel minimum Distance to FM translator 60 dBu contour For no For no minimum separation Required interference Required interference separation (km) 10.6 or received received (km) required 10.8 MHz -------------------------------------------------------------------------------------------------------------------------------------------------------- 13.3 km or greater............................................
edocket.access.gpo.gov /cfr_2003/octqtr/47cfr73.807.htm   (1275 words)

 FCC/MMB/PRD/Low Power FM Radio   (Site not responding. Last check: 2007-10-22)
The stations will be required to protect existing stations on the same (co-channel) channel, the next (first adjacent channel) channel, and the channel two channels away (second adjacent channel).
In a change from general practice, the new stations will not be required to protect stations three channels away (third adjacent channel).
For example, under rules applicable to existing full power stations where there is a station on 93.5, there is currently no station in the same geographic area on 93.7 (the first adjacent channel), 93.9 (the second adjacent channel) or 94.1 (the third adjacent channel).
www.panaxis.com /lpfm.html   (576 words)

 Headend   (Site not responding. Last check: 2007-10-22)
The HPM55-* is an adjacent channel audio/video modulator specifically designed for headends requiring proven performance.
The HSM55-* is an adjacent channel audio/video modulator specifically designed for headends requiring proven performance.
All channel conversions are performed using simple front panel buttons and a large LED display indicating input and output channels.
www.cencom94.com /gpage.html7.html   (607 words)

 9CAP flapperon ??? - RC Groups
In this mode, channel 6 is for flap and
channel 7 is a spare channel, until you configure the second aileron
Two channels are reserved if you pick 5 and 6 as a setting.
www.rcgroups.com /forums/showthread.php?t=78032   (2087 words)

 BROADCASTPAPERS.COM   (Site not responding. Last check: 2007-10-22)
The need to fit over 1,600 new digital television channels into the available television broadcast spectrum was an arduous task undertaken by the FCC.
One is the inherent noise immunity of the digital 8-VSB signal and another is the lower average DTV power required for equivalent coverage.
For example, in Pittsburgh, where digital channels are assigned to 25, 26, 38, 42, 43, 48 and 51, two digital adjacent channel pairs exist.
www.broadcastpapers.com /radio/HarrisRTAC02.htm   (564 words)

 ISS interference issues
Even 15k channel separation does not work (recommended terrestrial spacing for FM repeaters using a 15k channel is 75 miles between repeaters).
After 12 years of experiment with Mir, we came to the conclusion that 25k channel spacing was minimum to avoid qrm from terrestrial stations or other satellites and 30k channels spacing was ideal.
In my opinion, a small percentage of the QRM being received by ISS on 145.990 is caused by adjacent channel interference caused by the repeater inputs on 146.010 and other users close to the 145.990 channel.
www.marexmg.org /fileshtml/issinterferenceissues.html   (666 words)

 LPFM Application Dispositions   (Site not responding. Last check: 2007-10-22)
to prescribe LPFM station third adjacent channel interference protection standards and to prohibit any applicant from obtaining an LPFM station license if the applicant has engaged in the unlicensed operation of a station in violation of Section 301 of the Communications Act of 1934, as amended.
Under Section 73.807, an LPFM station must meet specified co-, first-, and second adjacent channel spacings and IF channel spacings to full power FM and FM translator stations, and co- and first adjacent channel spacings to other LPFM stations.
Providing an opportunity to amend to different channels after the close of a window would make staff determinations of mutual exclusivity and the administration of the selection procedure for mutually exclusive applications inherently subject to duplicative reevaluations.
www.mbcradio.org /lpfm/appdispositions.html   (2426 words)

 Channel Assignment Algorithms Satisfying Cochannel and Adjacent Channel Reuse Constraints in Cellular Mobile Networks - ...   (Site not responding. Last check: 2007-10-22)
Abstract: Recently improved channel assignment algorithms for cellular networks were designed by modelling the interference constraints in terms of a hypergraph [1].
Receiver filter responses impose restrictions on simultaneous adjacent channel usage in the same cell or in neighbouring cells.
We first present some heuristics for designing fixed channel assignment algorithms with a minimum number of channels satisfying both cochannel...
citeseer.ist.psu.edu /sarkar98channel.html   (397 words)

 [No title]   (Site not responding. Last check: 2007-10-22)
If the signals on adjacent channels interfere with each other, they will affect the quality of cell-phone and (eventually) TV signals—something cell-phone subscribers and TV viewers won’t tolerate.
At these points, the adjacent channel power for some base-station amplifiers could be as high as 70 dB below a transmitter’s in-channel average power (Ref. 1).
You’ll have to scale that value to match the channel bandwidth of your signal, using the phase noise value and the offset used for the adjacent channel measurement (i.e., 5 MHz or 6 MHz).
www.reed-electronics.com /tmworld/index.asp?layout=articlePrint&articleID=CA187321   (1256 words)

 Adjacent Channel - ABC Reception Advice
When new digital services are allocated channels next to existing analogue channels it may create a problem called adjacent channel interference.
The wider 8 megahertz bandwidth receivers allow the adjacent digital TV transmission to be received, corrupting the analogue service, while a 7 megahertz receiver effectively filters out the adjacent channel service.
If you are suffering upper adjacent channel interference affecting the sound, you could select mono sound reception rather than stereo, which will limit the extent of interference.
www.abc.net.au /reception/tv/adjacent_channel.htm   (451 words)

 [No title]
b) Consideration of the overall, uplink and downlink adjacent channel protection ratios required for 27 MHz digital BSS transmissions, in the case of interference from analogue emissions, when the adjacent channels are spaced at 19.18 MHz.
However, pending further studies to quantify the effects of the non-linear channel, the model given in Annex 3 should be applied to evaluate D ( fo).
For the associated adjacent channel PRs, values lower than those defined in Appendix 30 (15 dB) are foreseen, however further studies are required in order to confirm this assumption.
www.itu.int /itudoc/itu-r/archives/irg-gte/gte-3/6_ww6.doc   (6813 words)

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