Ultralight For Sale

Vhf Air Band

VHF/Am/Fm Band Separator $66.94 VHF/Am/Fm Band Separator Shakespeare AMFMVHF Marine Band Separator - VHF/AM/FM BAND SEPARATOR

Ms-Ra200G Am/Fm/Weather Band Vhf Receiver(Pack of 1) $640.99 Fusion Ms-Ra200G Am/Fm/Weather Band Vhf Receiver Sirius Ipod

Daisy Powerline Slingshot Replacement Band $4.25 Replacement slingshot band- fits Models F16, B52 and P51.

Marksman 3330 Slingshot Band Replacement Kit $4.25 For Marksman 30.06, 3027, 3040, 3047, and 3061 Fits most tubular band slingshots with 1/4" (6.35mm)diameter yokes Package includes one band with two vinyl yoke retainers.

Nady DKW-3 VHF Receivers $29.99 Nady DKW-3 VHF Receivers The DKW-3 R is Nady's unique tower-design VHF wireless receiver included in the DKW3HT handheld wireless mic system and the DKW3LT lavaliere wireless system. A perfect entry level unit, the DKW-3 R features jumbo LED power on, transmitter on and audio peak indicators. And despite its low price, the DKW-3 R offers high-band VHF (170-216 MHz) operation, advanced companding circuitry for a wide dynamic range, and a typical operating range of up to 500+ feet line-of-sight. An ideal replacement or backup unit for systems belonging to auctioneers, teachers, and aerobic instructors. PRODUCT FEATURES: High-band VHF (170-216 MHz) operation Advanced companding circuitry Space saving design Portable and easy to use IDEAL FOR: Replacement or backup Public address Aerobics instructors COMPONENTS INCLUDE: receiver DKW-3 R VHF receiver Warranty: 3 year manufacturer's limited warranty Get Your Nady DKW-3 VHF Receivers Today!

8' VHF Antenna - White $164.94 8' VHF Antenna - White VHF Antenna6dB GainDigital Antenna's ultimate, award-winning 8' VHF antennas combine 6 dB gain, ruggedness and a pristine finish to give you the most superior antenna available. Even in the harshest conditions, these antennas will maintain their beautiful glossy finish for years. Built to withstand high speeds, these antennas are ideal for radar arches and T-tops on speedboats, yachts and commercial vessels.All of our antennas are made in the USA, assembled, tested and tuned by hand for maximum performance, quality and durability.All 8' VHF Antennas Feature:Powerful brass radiators Soldered connections Power directing ferrite choke bead High gloss urethane finish 316 stainless steel ferrule 6dB gain 800 Series:Mount: Stainless steel double female ferrule for mounting 114 threaded base Connector: Highest quality female SO-239 (UHF) Cable: Not included use our VHF/AIS cables and two DA645 connectors Manufacturer: Digital Antenna Manufacturer Part Number: 829-VW Manufacturer Name: DIGITALANTENNA Dimensions: " Height x " Width x " Depth Standard Warranty: 0Year(s) Antenna Band: VHF Cable Length (Feet): N/A Color: White Construction: Fiberglass DB Gain (dB): 6 Ferrule Type: Stainless Steel Length (Inches): 8' Package Contents:

5226-FLT 8' VHF Antenna $201.94 5226-FLT 8' VHF Antenna Style 5226-FLT Galaxy® Eliminator™ Series 8' VHF 6dBCollinear phased 5/8-wave elements with special filtering sleeve to suppress intermodulation interference.If you boat near busy seaports, in harbors or just offshore of major cites and are troubled with annoying squawks and squeals erupting from your VHF radio, the 5226-FLT is for you. Using Shakespeares revolutionary filter technology, the 5226-FLT provides all the performance of the award-winning, flagship Galaxy® 5225-XT, plus it can significantly reduce annoying Out-of-Band and Intermod Interference caused by pagers, land mobile radios and other signals near the marine VHF radio band. And, it does this with virtually no effect on transmit range. The 5226-FLT features the extra tough Galaxy® fiberglass with its black, high-gloss polyurethane finish. Maximum range and quality in a great looking antenna.Brass and copper elements to maximize range and efficiencyStainless steel ferrule with standard 1"-14 threadExclusive Shakespeare Galaxy® Black finishIncludes 20' RG-8/X cable and a PL-259 connectorSuggested mount: Style 4187 stainless steel ratchet mountOne sectionShakespeare Limited Warranty: 5 yearsTechnical Specifications:Frequency:VHF Marine BandBandwidth:3 MHz within 2.0:1 VSWRSWR:nominally 1.5:1 at 156.8 MHzImpedance:50 ohmsGain:6 dBMax Input (Watts):30 wattsDC Ground:YESHeight (feet):8Polarization:Vertical

Cobra HH425 Marine VHF Radio $116.99 15 Marine / 10 Weather 3 Year 5 Hour 5 W 7.2 V DC The HH425 has the same great VHF radio features as the MR HH325 VP. In addition, it has Cobra's exclusive Rewind-Say-Again feature, GMRS Channel Dual-Band functionality, a 1900 mAh Lithium Ion Polymer Battery, S.A.M.E. Weather Alert Filtering and a Rapid 3-4 hour Charger. This is a professional quality VHF radio but it is also the world's first combination VHF/GMRS radio. Alkaline Cobra Cobra Electronics Corporation HH425 HH425 Marine VHF Radio Handheld MRHH425LIVP Marine Radio VHF www.cobra.com

Base-Loaded AM / FM / VHF Separator $65.94 Base-Loaded AM / FM / VHF Separator Shakespeare Style 4357-SAM/FM/VHF MARINE BAND SEPARATOREliminate the need for separate AM/FM antennas and operate AM/FM and VHF radios at the same time without interfering with VHF radio performance.Complete with 10' RG-62 AM/FM cable, 3' RG-58 VHF cable, and connector installed. Works with all types of marine VHF antennas.

10 VHF Antenna $51.94 10" VHF Antenna Shakespeare Style 5911 THE STOWAWAY™ Emergency VHF Flex Antenna Unity GainLOADED 1/4 WAVE WHIPComes packed in a 12™ weather-resistant, plastic tube which can ™stow away™ in an easy-to-reach location for instant emergency capability if your main antenna becomes broken or disabled. Complete with 12' cable, connector, and rubber suction cup for fast, easy mounting to any smooth horizontal surface.Flexible vinyl outer covering10™ overall lengthVelcro strips for storage includedTechnical Specifications:Frequency:VHF Marine bandBandwidth:N/ASWR:Adequate across Marine Band. Precise SWR depends on antenna locationImpedance:(Ohms): 50Gain:UnityMax Input (Watts):25DC Ground:YESTermination:12' RG-58 cableHeight (feet):10"Polarization:VerticalRadiation pattern:Omini-directional

Marksman 3055 Tapered Band Slingshot $11.99 Wrist Brace

17.5' VHF Radio $403.94 17.5' VHF Radio Shakespeare Galaxy Style 5018-FLT Eliminator™17' 6" VHF 9dB GainPhased 1/2 wave elements in a collinear array with special filtering to suppress Out-of-Band InterferenceThis antenna implements Shakespeares innovative filtering technology that helps get pager and other Out-of-Band interference under control in installations demanding taller, higher gain antennas. In busy radio areas like harbors, the antennas filter can make a big difference in how much RF garbage you hear. Working with your radios own rejection circuitry, the 5018-FLT can actually improve the fidelity of your VHF radio. Except for the added filter, the 5018-FLT is otherwise like Shakespeare's acclaimed 5018. Its highly sophisticated design is outstanding for long distance communications.Brass and copper elements to maximize range and efficiencyStainless steel ferrule with standard 1"-14 threadIncludes 20' RG-8/X cable and a PL-259 connectorSuggested mount: Shakespeare Style 409-R or 410-R mounting kitTwo sections: Base 105", Tip 105" UPS ShippableShakespeare Limited Warranty: 5 yearsTechnical Specifications:Max. Power Input:30 wattsSWRnominally 1.5:1 at 156.8 MHzBandwidth:3 MHz within 2.0:1 VSWRFrequency:VHF Marine BandFilter Loss:less than 0.25 dBDC Grounding:YesPolarization:VerticalImpedance:50 ohms

VHF 300 AIS Radio $999.99 VHF 300 AIS Radio VHF 300 AISThis space saving, black box, marine VHF radio offers multi-station support and options like an integrated dual band AIS receiver. The VHF 300 series marine VHF radios include many of the high-end features and capabilties found in the VHF 200 series such as full Class D Digital Selective Calling (DSC) with NMEA 2000 and NMEA 0183 capability, 25 watts of transmit power, NOAA weather alerts and position tracking. In addition, the VHF 300 series offers a patent-pending voicemail feature which allows users to record a 15-second message and send it to another DSC capable VHF radio. Boaters can also replay up to 90 seconds of the last incoming voice transmission at the touch of a button.Because the black box can be mounted anywhere out-of-sight, the VHF 300 series saves important real estate on the helm. Boaters operate the unit via the GHS 10/10i full-function remote microphone. These handheld remote mic stations feature a crisp two-inch LCD display, dedicated buttons for frequent tasks, and three soft buttons for dynamic controls. The VHF 300 series supports up to three GHS 10/10i remote mics for vessels with multiple stations, and uses either the supplied four inch active speaker with volume knob, the passive speaker contained within the GHS 10/10i, or an optional third-party passive speaker. With multiple stations, the system can even be used as an on-board intercom.Features: Space-saving black box configuration helping save important real estate on the helm Up to 25 watts of transmit power - user-selectable transmit power: 1 watt or 25 watts Operate every feature using the included GHS 10 or GHS 10i full function wired mic (supports up to 3) Includes a four-inch active speaker for on-boat intercom capabilities Full class D Digital Selective Calling (DSC) capabilities with a built-in dedicated DSC receiver NMEA 2000 and NMEA0183 interface capabilities Connect with NMEA 2000 capable Garmin chartplotters and autopilots for integrated position tracking and other safety features Position tracking - locate and keep tabs on up to 3 other vessels Automatic and manual fog horn signals - plus adjustable base fog frequencies Hailer/fog horn output - 30W Two-way hailer functionality - listen back when connected to a compatible horn speaker Voicemail feature allows users to record a 15-second message and send it to another DSC capable VHF radio Replay up to 90 seconds of the last incoming voice transmission LOCAL receiver mode to improve receiver performance in busy port environments The GHS 10/10i has a dedicated button for easy, one-touch access to channels 16/9 Receives NOAA Weather Alert Multi-lingual user interface: English, French, Italian, German, and Spanish Auto power on- radios automatically power on with the boat's start-up

VHF 300 Radio $574.94 VHF 300 Radio VHF 300This space saving, black box marine VHF radio offers multi-station support and options like an integrated dual band AIS receiver. The VHF 300 series marine VHF radios include many of the high-end features and capabilties found in the VHF 200 series such as full Class D Digital Selective Calling (DSC) with NMEA 2000 and NMEA 0183 capability, 25 watts of transmit power, NOAA weather alerts and position tracking. In addition, the VHF 300 series offers a patent-pending voicemail feature which allows users to record a 15-second message and send it to another DSC capable VHF radio. Boaters can also replay up to 90 seconds of the last incoming voice transmission at the touch of a button.Because the black box can be mounted anywhere out-of-sight, the VHF 300 series saves important real estate on the helm. Boaters operate the unit via the GHS 10/10i full-function remote microphone. These handheld remote mic stations feature a crisp two-inch LCD display, dedicated buttons for frequent tasks, and three soft buttons for dynamic controls. The VHF 300 series supports up to three GHS 10/10i remote mics for vessels with multiple stations, and uses either the supplied four inch active speaker with volume knob, the passive speaker contained within the GHS 10/10i, or an optional third-party passive speaker. With multiple stations, the system can even be used as an on-board intercom.Features: Space-saving black box configuration helping save important real estate on the helm Up to 25 watts of transmit power - user-selectable transmit power: 1 watt or 25 watts Operate every feature using the included GHS 10 or GHS 10i full function wired mic (supports up to 3) Includes a four-inch active speaker for on-boat intercom capabilities Full class D Digital Selective Calling (DSC) capabilities with a built-in dedicated DSC receiver NMEA 2000 and NMEA0183 interface capabilities Connect with NMEA 2000 capable Garmin chartplotters and autopilots for integrated position tracking and other safety features Position tracking - locate and keep tabs on up to 3 other vessels Automatic and manual fog horn signals - plus adjustable base fog frequencies Hailer/fog horn output - 30W Two-way hailer functionality - listen back when connected to a compatible horn speaker Voicemail feature allows users to record a 15-second message and send it to another DSC capable VHF radio Replay up to 90 seconds of the last incoming voice transmission LOCAL receiver mode to improve receiver performance in busy port environments The GHS 10/10i has a dedicated button for easy, one-touch access to channels 16/9 Receives NOAA Weather Alert Multi-lingual user interface: English, French, Italian, German, and Spanish Auto power on- radios automatically power on with the boat's start-up

Marksman 3355 Slingshot Hyper-Velocity Band Replacement Kit $5.46 Tapered bands provide 30% greater velocity Marksman's hyper-velocity bands represent the ultimate in slingshot bands. And, because of their easier pull, you don't have to strain to hold your position before releasing a shot. This makes shooting easier and more fomfortable- with increased accuracy. Fits Marksman Laserhawk slingshot models 3006(T), 3055 and 3060(L) but also fits Marksman models 3025, 3040, 3041 and most slingshots with 1/4" diameter yokes. Package includes one band with two vinyl yoke retainers.

23' VHF Antenna $455.94 23' VHF Antenna Shakespeare Style 5208-3 VHF Marine23' LENGTH, 9dBPHASED 1/2-WAVE ELEMENTS IN A COLLINEAR ARRAY WITH CHOKING STUB TO SUPPRESS CABLE RADIATION AND A BAND SPREAD MATCHING SLEEVEThe Style 5208-3 puts all the quality and performance of Shakespeares Ocean Twin 5208 into a three-section configuration. The Style 5208-3 is UPS shippable. The antenna delivers performance and then some. Its nine phased 1/2-wave element, 23-foot design means long distance communications in heavy seas... no problem!Brass and copper elementsChrome-plated brass ferrulesIncludes 20' RG-58 cable and a PL-259 connectorSuggested mount: Shakespeare Style 410-R Mounting Kit for deck or side mountingThree sections: Base 75"; Middle 100"; Tip 105"Shakespeare Limited Warranty: 2 yearsTechnical Specifications:Frequency:VHF Marine bandBandwidth:5 MHzSWR:1.5:1 @ 156.8 MHzImpedance:(ohms): 50Gain:9 dBMax Input (Watts):50DC Ground:NOTermination:15' RG-58 cableHeight (feet):23Polarization:VerticalRadiation pattern:Omni-directional

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Scanning VHF air band

Vhf Transceiver

Why does a vhf transmiter desense's all nearby receivers?

Hi there. Can someone explain to me why does a transceiver desense's all nearby recievers while transmiting? Does this mean that there some sort of rf power leak from the transmitter? Thank you.

No, it's not a power leak from the transmitter.

Receiver desense happens when the nearby signal overloads the "front end" - the part before the first IF conversion - of the receiver. Basically the effect of the signal, even if not the signal itself, gets "downstream" in the receiver even though it's on the wrong frequency. This fools the receiver into thinking "hm, there's a strong signal coming in" (even though it's not on the right frequency) and the Automatic Gain Control (AGC) circuit accordingly turns down the RF sensitivity.

M604 Vhf Marine Transceiver Wtrprf Vhf Dsc Black 2-Way Hailer $666.94 M604 Vhf Marine Transceiver Wtrprf Vhf Dsc Black 2-Way Hailer Icom Icom M604 VHF Marine Transceiver - WTRPRF VHF DSC BLACK 2-WAY HAILER

M604 Vhf Marine Transceiver Wtrprf Vhf Dsc Grey 2-Way Hailer $666.94 M604 Vhf Marine Transceiver Wtrprf Vhf Dsc Grey 2-Way Hailer Icom Icom M604 VHF Marine Transceiver - WTRPRF VHF DSC GREY 2-WAY HAILER

Cobra Marine Vhf HandHeld Transceiver 2-Way Radio MR-HH300VP MRHH300VP $79.16 Cobra Marine Vhf HandHeld Transceiver 2-Way Radio MR-HH300VP MRHH300VP

Handheld VHF Marine Transceiver $197.94 Handheld VHF Marine Transceiver IC - M72 VHF Marine TransceiverThe radio with MORE:Power (6 Watts)Waterproof (IPX8)Form Factor (easy to hold and operate)Compact Body, Great "Form Factor"A compact design, hourglass body-shape and comfortable side grips give the IC-M72 an outstanding "form factor" its easy to use with just one hand!Highest available power! 6 WattsThe IC-M72s 6 Watts¹ of transmit power can carry a conversation a long way. A large capacity 2000mAh Lithium-Ion battery allows for 1516 hours of operation, under normal conditions².1 5W for Australia version, *2 5% Transmit, 5% Receive, 90% Stand-byImpressive Force5AudioThe M72s impressive audio output (600mW typ.&#42) is loud enough to hear in most any marine environment even over loud engine noise.* 10% distortion, 8ohm loadSubmersible PLUS (IPX8)The IC-M72 offers Icom's best-ever protection against water intrusion. This radio has been tested to survive after being submersed in 1.5m (4.9ft) depth of water for 30 minutes.Wide Viewing Angle LCDA wide viewing angle, high intensity LCD is used in the IC-M72, offering bright, easy to read characters. The bright LCD backlighting and backlit keypad is great for nighttime operation.30% Shorter AntennaThe IC-M72s antenna is engineered to perform with typical Icom efficiency even though it is nearly 30%* shorter than previous Icom marine antenna.&#42 IC-M72s antenna length is 115mm; 417/32 in.Additional FeaturesAuto scan function to start scanning when receiving no signalAuto power save functionBattery indicator shows remaining battery power in 4 levelsInstant access to Ch. 16 and Ch. 9 (or call channel)Auto WX scan and WX Alert functionSimple add/delete TAG scanning operationBuilt-in UT-112 compatible voice scrambler (Depending on version)AquaQuake draining function emits a vibrating sound and clears water away from the speaker grill

marine VHF Hand-Held Transceiver(Pack of 1) $331.99 Cobra Marine Hand Heldvhf Radio Vhf RadioSelectable Power Outlet 1, 3 Or 5 Watts U.S., Canada And International ChannelsAll 10 Noaa/Weather Channels Weather Alerts With An Audible Tone And Visual Alarm Instant Channel 16/9Signal St

BBT-789 VHF/UHF FM Transceiver $27.14 High capacity, Li-ion battery design Battery save, CTCSS, DCS Sound register function, humanism design Flashlight function RF high power output > 5W Package Size: 235*180*60 mm Weight: 407 g

HONGDA HD-K99 Two Way Radio VHF/UHF FM Transceiver $41.51 Transceiver:16 memory channelsPower output: 5W or 1W Channel spacing: 12.5KHz, 25KHz. Talking distance: 3-10KM CTCSS(QT) / CDCSS(DQT) Urgent Alert, and VOX Frenquency: 136-174MHz, 400-470MHz. Speak channel number in English or Chinese Scan Feature Size: 250*170*65 mm

Simrad Rs25 Dsc Vhf Radio $269.99 Simrad Rs25 Dsc Vhf Radio . This versatile DSC VHF radio has everything that the boat owner needs to communicate with the shore, other vessels, and even between individuals on board. The Simrad RS25 is built to withstand all conditions and is designed with simple, intuitive controls that crew and guests will find quick to master and easy to operate in the event of an emergency. Position Polling, Track your Buddy and Group Call capabilities are beneficial on boats of all sizes. Whether cruising, racing, or fishing with other vessels, the RS25 allows you to monitor other vessels positions and provides fleet-wide broadcasting. Larger boats will appreciate the optional Bluetooth remote handsets with a range of up to 100m. In addition to full radio control, the remote handset provides intercom and conference capability. Communicate easily with other crew members throughout the vessel. Class D DSC fixed VHF transceiver with fully operational fist mic (EU shown) Optional Bluetooth handsets (u

Simrad Rs10 Dsc Vhf Radio $169.99 Simrad Rs10 Dsc Vhf Radio . The Simrad RS10 offers excellent value as a versatile, full-feature DSC VHF radio built to withstand tough conditions on any vessell. Perfect for RIBs and open boats as well as sail and powerboats, the Simrad RS10 has everything that the boat owner needs to ensure that he has the communications capability for a safe day on the water. The dedicated distress button ensures that help can be summoned in seconds, and the watch and scan functions enable the user to monitor selected channels. With its large and easy to read display, the Simrad RS10 clearly displays the Lat/Lon position and Local Time alongside critical VHF Channel information when integrated with GPS. Class D DSC fixed VHF transceiver with fist mike Position Polling and Group Call capabilities Dual watch / tri watch and scan functions ATIS facility for inland waterways Displays latitude and longitude when connected to a GPS 25W / 1W transmission power Distress call button Waterproof to JIS-7 and NM

transceiver $39.99 ATEN - Transceiver - phone - external

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Kenwood TM-281a VHF Transceiver

Radio Computer

Tabletop Radio $226.19 - Internet radio (iRadio) in a wooden cabinet- Network music player- High quality full-range stereo speakers (2"x5"W)- Immediate access to over 6,000 internet stations- Player music collection from computer- Connect to Windows Shares or UPnP servers- Supp

Squeezebox Radio $189.94 A compact all-in-one network music player and alarm that lets you rock the house with the digital music on your computer and the Internet.Compact designYour Logitech® Squeezebox Radio fits easily just about anywhere in your home-the kitchen, bedroom, bathroom, even the patio-without taking up a lot of counter space.Easy access to digital musicYou can play songs from your personal library, tune in to thousands of Internet radio stations, or connect to online services like Pandora®, Slacker®, and Rhapsody®.*Wireless connectivityNo wires needed-true 802.11g wireless technology lets you enjoy the music on your computer in any room.Big sound from a small packageYou’ll enjoy high-quality sound with very low distortion thanks to a two-way speaker and support for 24/48 kHz encoding.Watts? What? Learn more in the audio glossary.Simple, guided setupYou’ll be listening within minutes-it’s easy to get connected, browse Internet radio stations, and sign up for online music services. Or attach your iPod.Learn how easy it is to set up a Squeezebox.2.4-inch color screenIt displays album art, track and station information, visualizers, screen savers, and more.Auto-dimming display and alarmThis compact player is an ideal bedside companion. The display adjusts to any lighting condition-so it’s never too bright or too dim.Plays most digital music formatsIt supports just about any format you’ve got, including MP3, FLAC, WMA, WMA Lossless, AAC, Apple Lossless, WAV, and AIFF.Support for Wi-Fi and EthernetNo wires needed-seamless integration with your existing home network lets you listen to the music on your computer in any room.* Registration/subscription may be required. Fees may apply.

Radio Jxl Broadcast From Computer Hell Cabin $19.99 Track Listing: (DISC 1:), (DISC 2:), 1. Intro 3 AM, 1. Intro 3 PM, 2. Chilled, 2. Tennis, 3. Crusher - (featuring Saffron), 3. Dubzilla, 4. Casio, 4. Don't Wake Up Policeman - (featuring Peter Tosh & Friends), 5. Angels - (12 Inch Cut mix, 12 Inch Cut), 5. Reload - (featuring David Gahan), 6. Breezer - (featuring Sasha), 6. Spirits - (featuring Saffron), 7. Angels - (featuring Gary Numan), 7. Nudge, 8. Perfect Blue Sky - (featuring Robert Smith), 8. Red, 9. Beauty Never Fades - (12 Inch Cut mix, 12 Inch Cut), 9. Between These Walls - (featuring Anouk), 10. Access to the Excess - (featuring Chuck D), 10. Cosmic Cure, 11. Catch Up to My Step - (featuring Solomon Burke), 11. Rehsurc, 12. Never Alone - (featuring Terry Hall), 13. Configuring Audio System, 14. Little Less Conversation, A - (featuring Elvis Presley), 15. Beauty Never Fades - (featuring Saffron), 16. Broken - (featuring Grant Nicholas), 17. JXL Radio Technical Support

Myine The NPR Radio by Livio LV002 Internet Radio $145.99 The NPR Radio by Livio LV002 Internet Radio Remote Control The easiest way to enjoy NPR at home or at the office, without the need of a computer One-touch star button to store up to 40 of your favorite stations Requires broadband Internet access and a wireless router Access more than 16,000 Internet Radio Stations Built-in clock with single alarm Ethernet Internet Radio LV002 Myine Myine Electronics, LLC The NPR Radio by Livio LV002 Internet Radio Yes www.myine.com

Practical Computer Applications in Radio Nuclide Imaging $50.7 No Synopsis Available

Myine Livio Radio by Pandora LV001 Internet Radio $145.99 Livio Radio by Pandora LV001 Internet Radio Remote Control Pandora is your personal DJ; Enter the name of an artist or song and start listening; Give songs a Thumb Up or Thumb Down and Pandora will instantly change the music selection to better match your tastes The easiest way to enjoy Pandora Internet Radio at home or at the office, without the need of a computer The first Internet Radio to feature the Thumb-up and Thumb-down controls right in the front of the unit Requires broadband Internet access and a wireless router Built-in clock with single alarm Ethernet Internet Radio LV001 Livio Radio by Pandora LV001 Internet Radio Myine Myine Electronics, LLC Yes www.myine.com

Computer $22.65 Computer

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Dreambook W7 Android Tablet PC with Voice Call, SMS, 3G Networks, GPS, Camera, FM Radio

How To Record Online Radio Shows On your Computer Easily

With the advanced technology of today's generation, you can do many unbelievable things with the use of gadgets and gizmos. An advanced technology can teach you on how to record online radio shows on your computer easily. You do not need to be a graduate of any IT course to be able to put together quality audio on your computer. There are numerous popular radio stations over the Internet that allow you to download and record free radio programs like music, news, radio talk shows, comedy, sports and among others. Some programs, however, do not allow you to save the audio file because of copyright reason. Nevertheless, this page will give you information on how to record online radio shows on your computer easily. Internet Radio Recorder To be able to record online radio programs, you must have a special Internet radio recorder. You can find one from any stores online and offline. This can be computer software or radio recording device. You need to get one that is used by people who work in a recording studio. You have to find the perfect internet radio recorder that permits you to record Internet radio stations and broadcasts. A gadget like this will allow you to record anything and streaming audio broadcasts from Internet radio stations. Things to Use in Recording On-line Radio Shows There are particular things that you need to gather aside from the recorder to be able to completed record online radio shows on your computer. Without those things, you cannot be able to record anything. Whatever you will learn on how to record Internet radio shows on your computer will become useless if the materials needed are missing. The following items listed below are the things you must have. 1. You need a microphone to have a clear and precise recording of audios. 2. You must eliminate ambient noise by going to a certain place where silence is dominant. Remember to avoid using any gadgets that can create sudden sounds like your cell phone. You must turn it off before you start recording. You should not also bring any animal since they are not easy to calm down if they want to bark. 3. You get other software you can use to record online radio shows. These are various programs used for recording purposes. Steps in Recording Online Radio Shows on Your PC Here are the easy tips on how to record online radio shows on your computer easily. 1. You start installing your chosen Internet radio recorder. After that, you click "Settings" to find the place where you will store the recorded radio audio files. Select the most appropriate output radio audio format in which MP3 is commonly used one. In fact, MP3 is the default format on most radio recorder software. 2. You open the Internet radio station where you wish to record radio music online. You being playing any songs, talk shows or news that you want to save. 3. The last thing to do is to save all the Internet radio files you have selected. You press the "Record" button to start recording as the song plays on your computer. These tips must be followed accordingly to have very good and clear recordings of online radio shows you want to save on your computer.
About the Author

Learning how to record online radio shows on your computer easily requires actual practice. You will never record anything unless you try doing it. If you are not sure of the best Internet radio recorder to use or not 100% sure guaranteed about recording, you can ask assistance from experts.

Aircraft Vhf

VHF Communication Systems on Larger Aircraft?

Could you please explain why the number 1 VHF Communications system on many aircraft types (737, 767, 747, A320, A330 etc) obtain its electrical power for operation from either the 28V dc Battery Bus or the 28V dc Essential Bus (effectively the Battery Bus) and NOT from another source, such as a 28V dc Bus or similar power source?

Thanks

Although different aircraft are often wired in very different ways, a common feature to just about all aircraft with multiple sources of electrical power is that essential equipment is distributed over the power sources. In other words, care is taken so that all radios do not get their power from the same source, and multiple autopilots can be powered by multiple power sources, etc. In this way, if one power source fails, only part of the onboard equipment is disabled (and possibly none of it, in cases where one source can be fed to another part of the electrical system in the event of a failure).

Often a given equipment item will have a standard power source (different from other equipment of the same kind, e.g., each FMC will draw power from a different source), plus at least one alternate power source that can be patched over to that equipment (automatically and/or manually) in the event of a failure.

Large airliners give the pilots manual control over many aspects of power distribution, but they also contain complex computerized logic that automatically switches power sources and bridges or isolates different branches of the electrical system based on changes in the available power sources. For example, if the APU is supplying power and the engines are started, typically the automatic control logic will shift from the APU to the main engine generators for power supply as soon as the latter are stable.

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VHF AIRCRAFT Communication Air to Air FREQUENCY

Latest Trends in Air Traffic Control System

Latest Trends in Air Traffic Control System  By Jamal Barki

 Air Traffic Control

The typical image people have of air traffic control (ATC) is that of a group of people in an airport tower who coordinate aircraft activity by staring at radar screens that use points of light to represent aircraft. While not fundamentally incorrect, this isn't a fair representation of the extent of ATC operations. This article will flesh out that simplistic image and introduce you to the equipment, technologies, and procedures that go into keeping aircraft and air travelers safe in the air and on the ground. We'll look at the way air traffic control is organized, and explore the communication technologies that air traffic controllers use to keep in touch with air crew and ground personnel. We'll also look at the radar technologies used to keep track of aircraft, and we'll end with a brief look at some next-generation technologies.

Safety and wake turbulence

The primary mandate of air traffic control is to ensure the safe transport of people and cargo by keeping aircraft at a safe distance from each other and expediting the flow of traffic. Air traffic controllers have access to sophisticated radar systems that provide an overview of the airspace they control, and they have communication tools to coordinate flight paths with the air crew. Pilots lack the tools necessary to get an overview of the airspace, so they have to rely on air traffic controllers to guide the aircraft through congested airspace.

Since aircraft travel at significantly higher speeds compared to other common modes of transport, the time available for pilots to react to a dangerous situation can be quite short. Thus it's essential that flight paths are carefully planned and managed to minimize the risk of a collision. This is especially true around major airports where the density of aircraft in a given volume of airspace is higher than average.

Turbulence created by wingtip vortices and exhaust gases from jet engines can be significant when aircraft are in close proximity. This phenomenon, called "wake turbulence," can adversely affect trailing aircraft if the distance between them falls below a certain limit. This limit depends on the mass of the two aircraft. For instance, a light aircraft following a heavy aircraft is more susceptible to wake turbulence than a heavy aircraft in the same situation. Therefore, aircraft approaching an airfield have to be carefully sequenced in a manner that takes such factors into consideration. Additionally, weather conditions such as low cloud, heavy rain, or snow blizzards can mean that pilots can't see other aircraft in the vicinity and have to use their instruments and instructions from air traffic control to navigate.

Types of ATC

Air traffic controllers are organized into various groups, each of which is in charge of handling a distinct portion of the aircraft's flight. Each group has a designated airspace that it controls, and aircraft are handed off to the next group of controllers as it approaches the limits of the prior group's airspace. The airspace controlled by each group is further divided into sectors that are themselves handled by individual controllers. The way these groups are organized varies from country to country and depends on the extent of controlled airspace and number of aircraft handled.

The Potomac TRACON facility controls approaches and departures in the airspace surrounding Baltimore Washington International, Washington Dulles, and Washington National airports.

The tower controllers are the most visible group. From their vantage point on the airport tower, they have a visual overview of all the important parts of the airport tarmac, such as runways and taxiways. Tower controllers monitor the airspace surrounding the airports and keep track of approaching and departing aircraft. At well-equipped airports, they may even have access to surface movement radar systems to monitor aircraft and support vehicles as they move on the ground.

Once the aircraft is in the air and clear of the airfield, tower control hands the aircraft off to a departure controller. These controllers are typically based at facilities a good distance from the airport. With the use of surveillance radars, they are able to monitor air traffic around the airport. These facilities are called Terminal Radar Approach Control (TRACON) facilities in the US. In an area like New York, where airports are close to one another, a TRACON facility can service multiple airports. The controllers here ensure that the planes approaching and departing the airspace they control are following designated flight paths and speeds. TRACON facilities also sequence the aircraft that are coming in to land, in order to ensure that they are adequately separated to minimize any wake turbulence effects. Departure controllers also need to take into account aircraft that may be flying through their airspace, and keep them separated from aircraft landing or taking-off.

As the aircraft exits the TRACON airspace, a facility known as an Area Control Center (ACC) takes over. These facilities monitor the aircraft's flight while in controlled airspace through remote radar stations. Each ACC will have a designated airspace that it supervises. An aircraft may fly through multiple ACC sectors as it flies to its destination, with each ACC handing off control of the aircraft to the next ACC as it exits the former's airspace. Once an aircraft gets closer to its destination airport, the ACC controllers hand off responsibility to the approach controllers at the local TRACON, who guide and sequence the aircraft to the active runway, and finally to the tower controllers.

ATC Radar Systems

Air traffic controllers use radar systems positioned at or near the ATC facility to get a real-time overview of the aircraft flying in the airspace they control. Radar technology for detecting aircraft first became popular during the wars in the first half of the last century and played a vital role in their outcome. First-generation radar systems served as early warning systems; these systems had relatively poor resolution, and their only purpose was to alert their operators to the presence of flying objects in the radar's field of view. These early radars operated by emitting a continuous radio signal and listening for any echos, but they weren't able to use these echos to gauge the size of the aircraft, calculate its ground speed or altitude, or determine if the aircraft belonged to an ally or the opposition.

After the war, radar technology was advanced with improved electronics and materials for antenna construction. This allowed for systems that were much more efficient and had higher resolution. The Air Traffic Controllers today are served by many types of radar equipment such as Primary Surveillance Radars (PSR), Secondary Surveillance Radars (SSR), and Mode S for monitoring traffic in the air, and Surface Movement Radars (SMR) for traffic on the ground.

Primary Surveillance Radar (PSR)

The Primary Surveillance Radar is the traditional form of radar that most people are familiar with. The radar sends a directed pulse into the atmosphere, and when that pulse encounters an object it gets reflected back to the radar station. By having precise knowledge of the orientation of the radar and the time between the sending and receiving of the radio pulse, the bearing of the object with respect to the radar station and its approximate distance can be calculated. The radar is typically enclosed in a dome to protect it from adverse weather. The PSR cannot determine the altitude or elevation of the aircraft relative to that of the radar station. For this to be possible, a second radar that sweeps the sky vertically would be required. However, such technology is typically only found in Precision Approach Radar installations at military facilities to assist pilots with landing aircraft.

The potential for an aircraft to be detectable by the PSR depends on its Radar Cross Section (RCS). The RCS depends on a number of factors, including the distance between the aircraft and the radar, and the size of the aircraft. A larger aircraft, for instance, would be visible at a greater distance than a smaller aircraft due to the larger surface area available for reflecting the radar waves. Other factors, such as reflectivity properties of the aircraft skin, the wavelength of the radar signal, and the angle at which the radar signal is incident on the aircraft (and thereby reflected), also play a part in how visible an aircraft is to the PSR.

Secondary Surveillance Radar (SSR)

The Secondary Surveillance Radar system—or Air Traffic Control Radar Beacon System (ATCRBS) as it is sometimes referred to—is comprised of the ATC radar installation and a transponder that rides onboard the aircraft being monitored. The origins of SSR lie in the "identify friend or foe" system used by the military to distinguish allied and enemy aircraft. While a Primary Surveillance Radar listens for reflected radio signals, the Secondary Surveillance Radar listens for messages from the aircraft's transponder. The radar rotates about the vertical axis similar to a PSR, but transmits a specific signal on 1030 MHz. This signal is subsequently received by the aircraft's onboard transponder, which responds with a reply on 1090 MHz. Much like the PSR, the bearing and distance of the aircraft with respect to the radar installation can be calculated with precise knowledge of the orientation of the radar when the signal was transmitted.

The SSR system has many advantages over PSR. Firstly, since it doesn't rely on radio waves being reflected back by the aircraft, the radar cross section of the aircraft does not form a part of the equation. All aircraft in range of the radar, regardless of size, composition, or distance from the radar, can be "heard" equally well. Secondly, since the signal received by the radar originates on the aircraft, the signal is subject to less attenuation compared to a PSR signal. This is because the reflected PSR signal has to travel twice as much as the SSR signal. This also implies that the signal transmission power for an SSR can be much lower than that of a PSR.

While SSR has many advantages, the prime disadvantage is that the system needs a properly functioning transponder on the aircraft for it to work. An aircraft without a transponder would effectively be invisible to the SSR. For this reason, PSRs are still used as a backup mechanism in most parts of the world. The Federal Aviation Regulations (FAR) in the US (and similar regulations in most countries) require aircraft operating in air traffic controlled airspace to have an operational transponder.

SSR Modes

The signal transmitted by the SSR is termed the "interrogation signal." There are different modes of interrogation that compliant transponders respond to. Civil aircraft typically respond to interrogation modes A and C.

In Mode A, the transponder responds with its squawk code, a unique identifier for the aircraft assigned by ATC comprising of four octal numbers. This code enables ATC to differentiate between the various aircraft being monitored, though it can also be used to discretely communicate the existence of an emergency situation onboard the aircraft. For instance, a squawk code of 7500 indicates that the aircraft has been hijacked, and a squawk code of 7600 indicates that the pilots are unable to communicate with ATC.

In Mode C, the transponder responds with the aircraft's pressure altitude, which is the altitude above sea level as calculated using the barometric reading at the aircraft's altitude. The altitudes reported are in 100-feet increments. This information is vital for ATC to ensure that aircraft flying in close proximity have adequate vertical separation.

Mode S is an improved secondary surveillance mode, and it operates over the same radio frequencies as SSR, making it backwards compatible. While Modes A and C in the legacy SSR system "broadcast" an interrogation message to all aircraft in the path of the radar beam, Mode S selectively interrogates individual aircraft using a 24 bit identifier that is assigned to the aircraft upon registration.

Mode S has a number of advantages over Modes A and C, the first of which is that its selective interrogation approach reduces the workload on the system, as it might be inundated with SSR replies in heavily congested airspace. Secondly, the legacy SSR system allowed for a transponder identification code of only four octal digits (12 bits) that yielded just 4096 codes (not including reserved codes) which were assigned by ATC. To complicate matters, this could be different for the same aircraft in different ATC sectors. As the number of aircraft increased over the past few decades, there was a scarcity in the number of available transponder codes, but move to a 24 bit addressing system alleviated the problem. Finally, the altitude reporting in Mode C was in increments of 100 feet, but this was improved to increments of 25 feet, allowing controllers to have a more accurate picture of aircraft positions.

Surface Movement Radar (SMR)

The airfield can be a busy place, with pushback tugs, tractors with baggage containers in tow, refuelling trucks, catering trucks, airport security vehicles, and (of course) aircraft. While the PSR and SSR provide controllers with an overview of aircraft in the air, the surface movement radar provides a real-time view of aircraft and support vehicles on the ground at airports. Most modern airports have Ground Control in charge of ensuring that critical patches of the airport tarmac such as active runways and taxiways are safe for moving aircraft.

Ground Control can observe all moving vehicles and aircraft on a radar screen overlaid on a map of the airport. As the objects being tracked by an SMR are relatively smaller than those tracked by a PSR or SSR, the radar uses a much shorter wavelength (and correspondingly higher frequency) with a narrow beam for a higher resolution result. Depending on the size of the airport, multiple installations of this sort may be required to cover all the critical parts of the airport. Enhancements to this basic system include having airport support vehicles installed with transponders that can be queried to ascertain location. Similarly, aircraft transponders can be queried to augment the radar display with call signs. Information from the tower radar can also be incorporated to display approaching aircraft. Newer systems can even aurally warn controllers of potential runway incursions and conflicts, so that action can be taken in time to avoid disaster. Such a system is generally called an Airport Movement Area Safety System.

Unfavorable weather conditions such as heavy rain and fog can lead to a reduction in visibility, making it difficult to monitor the tarmac. Runway incursions are a constant danger in such challenging conditions. A runway incursion is described by ICAO (International Civil Aviation Authority) as the incorrect presence of an aircraft, vehicle, or person on the protected area of a surface designated for the landing and take-off of aircraft. The Tenerife Airport Disaster, the deadliest accident in aviation history, was as a result of two aircraft colliding with each other on the runway. The incident occurred in heavy fog and at a time when the air traffic controller on duty could not see the two aircraft, nor could the two pilots see each other. A more recent incident that highlights the importance of the surface movement radar in emergency situations is the crash of british airways flight 038 on the threshold of runway 27L at London Heathrow Airport.

Air-Ground Voice Communication

In the early years of aviation, when there were fewer planes in the sky than we have today and there was not much need for pilots to communicate with ground personnel, signalling was often done using lights and flags. But with an increase in aircraft, a more efficient and unambiguous two-way communication system became necessary. At the same time, radio technology was progressing, and it became feasible for aircraft to have radio transceivers on board.

Aircraft communication in the early years was over the HF (High Frequency) range of the radio spectrum. In the US, each airline company had its own dedicated radio frequency over which company pilots communicated with their operators on the ground. But over time, with an increase in airliner companies and air traffic, this system soon led to a depletion in the available frequencies on the spectrum. The problem was resolved by setting up a common entity that provided air traffic coordination services. This allowed for a better use of the available radio spectrum, as pilots communicated with air traffic personnel over common frequencies. Over time, this system evolved to the air traffic control system we have today.

Modern civil aviation uses the HF (High Frequency) and VHF (Very High Frequency) parts of the spectrum for communication between aircraft and ATC. Military aviation in various countries are also known to operate in UHF (Ultra High Frequency). Early air to ground voice communication was over HF, but VHF started to get adopted in the 1930s and 1940s.

VHF communication

VHF is the predominant frequency range used by civil aviation in most parts of the world, and communication usually happens over the 118 MHz to 138 MHz frequency range via an amplitude modulated (AM) signal. (FM radio, in comparison, is over frequencies from 87 MHz to 108 MHz in most countries, and is of course, frequency modulated.) The frequency 121.5 MHz is reserved for emergencies in the VHF frequency range.

VHF transmissions rely heavily on a line-of-sight between the transmitter and receiver. This doesn't necessarily mean a visual line-of-sight, however, but a "radio line-of-sight" in the VHF part of the spectrum. Solid structures, such as buildings or the earth's surface, tend to attenuate the signal (or reduce its strength). Additionally, atmospheric layers do not refract or reflect VHF waves well. Due to these characteristics of VHF propagation, and due to the curvature of the earth, an aircraft below a VHF transmitter's radio horizon would typically fall outside its range. Thus the nature of the terrain and the height of the aircraft above the ground plays a part in determining whether it is in range of a given ground station operating over VHF frequencies.

For instance, the range would be severely curtailed for low-flying aircraft in hilly areas or urban areas with tall skyscrapers. In such cases, signal repeaters can be used to increase coverage. Theoretically, an aircraft at cruise altitude, flying in ideal weather conditions with a good quality transceiver can expect to communicate with a station unobstructed by hilly terrain about 200 nautical miles away (370 kilometers or 230 miles). In less than ideal real-world conditions however, this range can be significantly lower.

VHF operating frequencies are allocated to ATC stations in such a way that they do not interfere with each other, and since VHF relies on line-of-sight, frequencies can be reused by other distant stations. A typical activity for controllers is to pass on the frequency used by the next ATC sector to the pilot as the aircraft exits the ATC's airspace.

HF communication

When flying over large expanses of water, VHF communication, due to its line-of-sight nature becomes unusable. Additionally it would be impractical to construct, operate and maintain VHF relay stations in the middle of the ocean. So in these situations, HF can be used to communicate with an aircraft below the station's horizon and often many thousands of nautical miles away. In some cases, HF transmissions are known to have been successfully received on the other side of the planet. Thus pilots flying certain oceanic routes that are outside radar coverage use HF to periodically report their position to the oceanic control station for the sector they are flying in.

HF has some major drawbacks that make it impractical for more widespread applications. First, HF signal propagation is highly dependent on atmospheric conditions and solar activity, making HF communication comparatively noisy and unreliable. Due to this variability, ATC stations operating over HF have a number of alternative frequencies that they can operate over, and they switch to the frequency with the best signal propagation characteristics at the time.

It's also the case that HF signals have a longer wavelength than VHF signals, so the antennas used for transmitting and receiving are much larger, as well. And HF transmitters also operate at a higher power, since the receivers may potentially be hundreds of nautical miles away.

Next-generation Technologies

The aviation industry has been relatively conservative in its approach to adopting new technologies, so a number of the systems described so far are based on technology that has been around for at least a few decades. This conservatism is primarily attributable to the safety and reliability considerations that must be taken into account when making changes to existing equipment and procedures.

While tried-and-true systems do provide the required safety, this safety may at times come at the cost of efficiency. Critics of the current air traffic control systems claim that efficiency gains of many percentage points remain to be realized by more intelligent routing in controlled airspace that allows for lower separation distances between aircraft.

Currently, the Federal Aviation Administration (FAA) in the US is studying the implementation of various next-generation technologies to improve the efficiency of the ATC system while retaining or improving the level of safety. Next generation will incorporate global positioning satellites, digital communication networks, data networking, and improved weather forecasting to improve efficiency. Of all the technologies being considered, Automatic Dependant Surveillance (ADS-B) is being billed as the the future of air traffic control and as the backbone of the NextGen system.

Automatic Dependant Surveillance—Broadcast (ADS-B)

ADS-B is a relatively new technique (compared to use of primary and secondary surveillance radar) to monitor aircraft. The technique uses the global positioning system (GPS) to provide an accurate report of an aircraft's position. As the name suggests, this is a broadcast technique where an aircraft equipped with an ADS-B transponder routinely broadcasts data. Using similar information from all aircraft, the air traffic controllers can build an accurate picture of aircraft positions. ADS-B is able to provide information not unlike an SSR, but without the requirement for a radar installation or transmissions from a ground station.

The aircraft typically transmits its identity, current position, speed, and direction of travel (among other parameters) over a digital link, twice every second. Due to the broadcast nature of the data, other aircraft in the region can also receive this information and provide their pilots with an overview of the traffic in the neighborhood as well. One of the advantages of the ADS-B system is that the receiver can be relatively simple and inexpensive. Another advantage is that ground vehicles at the airport can use the same system to report their location on the airport tarmac which can be incorporated into the Airport Movement Area Safety System described earlier.

One of the disadvantages of ADS-B is that the system relies on the GPS system for accurate reporting of position information. Loss or degradation of the GPS signal could potentially put lives in danger. This can be mitigated to an extent by alternative sources of positioning information such as the European Galileo project, the Russian GLONASS project or the Chinese Beidou project, when they become fully operational. The other disadvantage is that a malfunctioning or inoperative transponder could render the aircraft invisible, or worse, broadcast false information. This is one reason for the continued use of surveillance radars as backup. Given the relative simplicity and cost-effectiveness of building an ADS-B transponder (compared to surveillance radars) and the open nature of the system, critics fear it is also a security hazard as it would in theory be possible to spoof data to represent aircraft that don't actually exist.

Listening to ATC and Tracking Aircraft

ATC and pilots communicate over open, well-advertised frequencies. Since VHF communication takes place using frequencies between 118 MHz to 138 MHz, a frequency range not commonly available on general purpose radio receivers, a scanner that can tune into these frequencies is required. It isn't unusual for serious aviation enthusiasts to invest in a good quality scanner to listen to their local air traffic controllers and pilots. Sites such as live ATC stream ATC broadcasts from various ATC facilities in the world. One must, however, exercise caution and check local laws first, as listening to ATC is illegal in certain jurisdictions. HF communications also occur over open, well-advertised frequencies and, unlike VHF, general purpose shortwave radios often have the frequency range to tune into oceanic ATC. Due to the nature of HF propagation, it may be possible to listen to controllers thousands of miles away, but the reception quality will vary.

The ADS-B system, as it operates currently, is an open system as well. It is possible to purchase an ADS-B receiver for as little as $600. A number of enthusiast sites such as flightradar24 (Scandinavian region), Zurich University of Applied Sciences' School of Engineering radar site (Switzerland) and Casper(Netherlands) provide an overview of aircraft in their region by listening to ADS-B transmissions.

References/Further Reading

• Aeronautical Radio Communication Systems and Networks - Dale Stacey (ISBN: 978-0470018590)
• Avionics: Elements, Software and Functions - Cary R. Spitzer (ISBN: 978-0849384387)
• Skybrary
• ATC Monitor

 

 

About the Author

The author is an Air Traffic Controller, Aircraft Accident Investigator and Aviation Safety Specialist. An Aircraft and Helicopter Pilot.