what is the difference bet VHF & HF?????
444045
hf is high frequency where as vhf is very high frequency. vhf is used more for local radio transmissions where as hf can transmit rf around the world. radio amateurs use hf bands (different set frequencies) for talking more long distance and vhf for talking via repeaters or just friends that they have in thier areas. emergency services like ambulance, police, fire will use vhf as they will just be talking locally. but it all depends what mode that the vhf/hf is set on aswell, u also have FM (frequency modulation) (used mostly in vhf/uhf) most radio stations use this mode, AM (Amplitude Modulation) (was what most radios started with that used voice transmissions and some radio stations still use this mode, CW carrier wave(morse code) used mostly in hf, USB & LSB (upper side band and lower side band) used mostly in hf for talking round the world.\nHope this helps\nGod bless
616403
In both cases, information (music, voice, video, whatever) is carried in radio waves (electromagnetic waves).  Think of waves on the beach.  They can differ in the height (amplitude) of the waves, and in the frequency of the waves (how close the waves are to each other).\n\nIn amplitude modulation (AM) ... the information is carried in the changes (modulation) of the amplitude of the radio waves.  All the waves from a particular radio source (e.g. a radio station) all have the same frequency, but different amplitude.\n\nIn frequency modulation (FM) ... the information is carried in the changes (modulation) of the frequency of the radio waves.   All the waves from a certain radio source have the same amplitude, but different frequency.
411245
That is commonly called "High Band VHF" and is licensed under Part 90 of the FCC Rules and Regs (Title 47).  There are pools of frequencies there for public safety, industrial/business, etc.
241961
Simple, I just recently got my license 1 month ago. Many Communities have an Ham radio club. For example Memphis, Tennessee has MARC (Memphis Amateur Radio Club) or Dallas, TX has DARC (Dallas area Amateur Radio Club). Go to Google and search for: {Your city} Ham Radio. Or http://www.dxzone.com/catalog/Ham_Radio/Clubs/North_America/USA/index.shtml has an incomplete listing. I took a class from our local club and the next day took the test. Its rather easy. The Amateur community tends to be outgoing. The club near me gave me a year free membership to welcome me to the community and my instructer programed my radio for me with the local repeaters. I hope you have good luck in finding your local club and enjoy amateur radio.\n\nBTW. Morse is not required to start!!!\n\nRevision: I just found this web site that should give additional information. http://www.hello-radio.org/\n\nKE5GYB \n73
104650
Let f1 = 35.0 kHz\nvbat = 12 m/s\nvsound = 330 m/s\n\na) f2  = vsound*f1/(vsound-vbat) = 330*35/(330-12) = 36.32kHz\n\nb) For bat f = (vsound+vbat)*f2/vsound = 342*36.32/330 = 37.64kHz\n\nc) It will obviously affect the answers
1015346
check these channels  SF1 / S F2 / TSI1 / TSI2 on \n\nhotbird   Freq.11525    27500    3/4  \ncode :   0E  /   76 2E 9C BB B1 12 DD BE\n\nand SLO1 / SLO2    Freq. 12303     27500   3/4 free but some match nit all\nthen u have change the codes for these channels as i give you and will work \nthe code is wroking since 4 days now if change just send e-mail and i will give you the new 1 .\n\nIF YOU DON'T KNOW HOW TO CHANGE CODE JUST GIVE ME WHICH KIND OF RECEIVER YOU HAS AND I LET YOU KNOW HOW TO DO THIS.
216733
Here's a link that'll help you best\nhttp://radio.about.com/library/weekly/aa013003c.htm
697740
Try a FM Booster attached to the radio - I could never get a signal in my basement (It's a game room with pool table, darts, etc...So NEEDED tunes!), then hooked up a FM booster that I got at Radio Shack and it worked great!
775512
If you mean communication by morse code, the answer is no. While radio-telex is also communication by radiotelegraphy, I suspect that this is not what you mean. Morse code has been dying for some time, with its steepest decline coming after the IMO discontinued the need for Radio Officers on Merchant Ships provided they were equipped with INMARSAT equipment and sufficient redundant (ie spare) radio equipment to make the need for a dedicated engineer to maintain them superfluous to requirements. I recall the decision well (it was in 1989) as I had only 2 months previously qualified as a Radio Officer. British Telecom (the main provider of coastal radio stations in the UK) closed down its 500KHz (MF R/T emergency frequency) listening on 1st January 1998, providing instead a constant listening watch on HF and VHF (2182KHz and Ch16 emergency frequencies respectively). It closed its commercial coastal radio stations in a phased operation beginning in June 1999.
905952
Commercial radio stations transmit signals using two types of schemes.....AM (Amplitude Modulation) and FM (Frequency Modulation).\n\nIn both types of schemes, the voice/music/audio is imposed upon what is known as the carrier wave. This carrier wave is generated at the radio station and has frequency within a certain portion of the range. For example FM radio stations typically have a range of 88 MegaHertz (Million Cycles Per Second) to 108 MegaHertz.\n\nSo, when your station changed from 93.9MegaHertz to 98.3MegaHertz, what they changed is the frequency of the carrier wave.\n\nThe music/voice/audio then is used to modulate (change) this frequency by a pre-determined amount.  Other radio stations are assigned carrier wave frequencies in such a way that two adjacent stations will not broadcast on top of each other.\n\nFor example, since your station now broadcasts on 98.3 MegaHertz frequency, the adjacent stations will be assigned frequencies of 98.5MegaHertz (above your station's frequency) and 98.1 MegaHertz (below your station's frequency).\n\nHope this helps.
1106438
buy a FM broadcasting set up
10500
I think the previous answer is geared towards channel allocation and not bit rate vs bandwidth.  I will try to clarify the issue.\n\nFirst, you must understand how FM works and how a digital signal converts to FSK (frequency shift keying).  Therefore I will use a simple example.\n\nEach bit takes up some frequency.  For example, the bit '1' could take up 5 Hz carrier frequency on the bandwidth spectrum and '0' could take up 6 Hz on the bandwidth spectrum.  Therfore, there is a seperation of 1 Hz between bits.  \n\nIf I send a '1' followed by a '0' then on a meter I should see 5 Hz freqency and then a 6 Hz frequency back to back.  We could speed this up to infinity and therefore have these 2 frequencies transmitting all data at infinite speeds.\n\nIn the real world however, a '1' may fall around the 5 Hz frequency but not exactly on it.  It may be about 5 Hz.  Why around 5 Hz and not exactly on it everytime?  Because in the real world we have noise in transmission lines.  Noise can distort the frequency causing it to be a little less than 5 Hz or a little more than 5 Hz.  Imagine if the '1' bit is transmitted but on the receiving end it ends up receieved as 5.5 Hz.  What happens now?  It's not quite 5 Hz and it's not quite 6 Hz.  Noise caused it to move 0.5 Hz away from 5 Hz.  It is in the middle of 5 Hz and 6 Hz.\n\nNow the receiving end has to decide if this is '1' or '0'.  What are the odds the receiving end gets it right?  By slowing down the speed the 1s and 0s that are transmitted , you can hold steady the 5Hz or 6 Hz for that bit.  The faster you go, the less accurate the bit will fall exactly where it should on the frequency.\n\nSo, what are some possible solutions?  Well, you can slow the frequency down or make the frequency seperation larger.  For example, make a '1' be 5 Hz and make '0' be 10 Hz.  Now you have 5 Hz seperation between bits instead of 1 Hz seperation.  Now if the frequency of 5.5 Hz is received, the receiving end can determine that this should have been 5 Hz.  It's highly unlikely it was originally transmitted at 10 Hz.  Therefore, the receiving end detects a '1'.  \n\nBut what have you lost by doing this increase in frequency seperation?  You have taken up more bandwidth.  Every cable has only so much bandwidth and if you have several channels on a cable all transmitting at the same time, you need to limit the amount of bandwidth each channel takes up or you will run out.\n\nSo, therefore, since most companies don't want to backdown on speed to the consumer (you), then they upgrade their technology (i.e. cables) to higher bandwidth cables such as fiber optic cables.\n\nI hope this helped.  Others, please feel free to expand on this topic.  I've only discussed FSK modulation.  Other techniques such as PSK, ASK, QPSK, bit stuffing, NRZI, CRC, and FEC codes can improve bit rate over channels.\n\nYou can read more about bandwidth limits.  Shannon and Hartley came up with a theorem which still holds today and is used quite extensively.  I even know someone who worked with Shannon at Bell Labs back in the day.  Shannon's theorem is C = BW*log2(1+S/N) where C is the channel capacity in bits per second,  BW is bandwidth, S is the signal power and N is the noise power.\n\nWF\nTelecom Engineer
45057
not all stations do this\nit depends on their licence from the FCC
110147
.   Frequency shift keying has a better signal to noise ratio than on off keying. One frequency indicates that the signal is "on" and the other frequency indicates that the signal is "off". Since both frequencys are close together a noise pulse will affect both frequencys and therefore cancel itself out. \n.   Frequency shift keying is used to send teletype and can also be used to send radio control signals.
150565
They are two ways of modulating a carrier wave to carry digital, i.e. binary, information.  In ASK the amplitude of the signal is varied between two levels to indicate a one or zero (on/off keying is a special case of ASK where one of the amplitudes is chosen to be 0).  In FSK the frequency is varied to indicate ones and zeros.  Both are applied in broadcast radio communications and wired data transmissions.  FSK is less suceptible to interference, like FM signals in general.
28291
here\n\nhttp://www.1037theq.com/main.html
8775
E = hf applies to light, not electricity.\n\nThe power consumed by AC current is assessed by the root mean square, which is equivilent to the peak amplitude divided by radical 2.  The frequency doesn't factor into the matter.