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#1
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Why don't voice radio communications use FM?
Perhaps this is a naive question, but: Why don't voice radio
communications for aviation use FM radio instead of AM radio? I realize there's substantial inertia in the installed base of AM equipment, but surely one could allocate some new frequencies to FM and use them in parallel for some years to ease the transition. The reason I ask is that improper and misunderstood radio communication is a leading cause of accidents, and so it seems that anything that can make that communication clearer would greatly improve safety. I can barely understand what I hear on the radio. It is true that the communication is very standardized, making it easier to guess what is being said, but the results are pretty unpleasant if one guesses wrong. On a related note, it has occurred to me that one could develop voice-recognition systems that understand the speech of a pilot and then repronounce what he says in an extremely standard synthetic voice. This could also improve understanding, especially for non-Anglophone pilots who speak with heavy accents. The same systems could clean up the speech so that it is absolutely standard, with no missing or added words. Of course, the issue here is that the system would be stuck if it cannot recognize what is being said, or if a completely non-standard utterance is made by the pilot. A natural extension of this would be systems that recognize standard phrases in one language and translate them to another, but that would be even more dangerous if the system ever failed. Still another idea is special training systems that listen to a pilot's speech and transcribe it, and point out any problems with understandability. Again, this would be most useful for non-Anglophone pilots, but it would work for anyone. If a machine can understand a pilot's speech clearly, then a human being should certainly be able to understand it that much more easily. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#2
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Why don't voice radio communications use FM?
"Mxsmanic" wrote in message news Perhaps this is a naive question, but: Why don't voice radio communications for aviation use FM radio instead of AM radio? Wouldn't that reduce the available frequencies? |
#3
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Why don't voice radio communications use FM?
Mxsmanic wrote:
The reason I ask is that improper and misunderstood radio communication is a leading cause of accidents, A leading cause of accidents? Where did you get this statistic? but the results are pretty unpleasant if one guesses wrong. Guess? If a pilot or controller is not able to comprehend the other side's transmission, there is no guess. "Say again?" is the phrase of choice and it is used all over the frequencies. -- Peter |
#4
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Why don't voice radio communications use FM?
Mxsmanic wrote:
Perhaps this is a naive question, but: Why don't voice radio communications for aviation use FM radio instead of AM radio? I understand it is because of a characteristic of FM called "capture effect" that blanks out weaker transmissions when two radios transmit at the same time. The listener would have no idea that a second, weaker transmission was being made. With AM, when two radios transmit on close frequencies, you either hear both signals poorly, or you get squeal, which is the sum of the two signals. This characteristic is considered important when you have elevated transmitters that can be hundreds of miles away, like on aircraft. |
#5
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Why don't voice radio communications use FM?
On Sat, 02 Sep 2006 14:40:40 +0200, Mxsmanic
wrote in : Perhaps this is a naive question, but: Why don't voice radio communications for aviation use FM radio instead of AM radio? I presume the reason stems from AM radio's introduction into aviation after CW was used prior to and during WW-I. The cost of re-equipping all aircraft with new radios is also not insignificant. I realize there's substantial inertia in the installed base of AM equipment, but surely one could allocate some new frequencies to FM and use them in parallel for some years to ease the transition. AM frequencies are currently 25 kHz wide. FM would require more bandwidth. Regardless, where would you place these newly allocated frequencies? The reason I ask is that improper and misunderstood radio communication is a leading cause of accidents, What is the source of that questionable statistic? and so it seems that anything that can make that communication clearer would greatly improve safety. Hence the popularity of Active Noise Reduction headsets. I can barely understand what I hear on the radio. Do you use an ANR headset? It is true that the communication is very standardized, making it easier to guess what is being said, but the results are pretty unpleasant if one guesses wrong. Request 'say again' if in doubt. On a related note, it has occurred to me that one could develop voice-recognition systems that understand the speech of a pilot and then repronounce what he says in an extremely standard synthetic voice. What would you estimate the cost of re-equipping all aircraft with such a system might be? This could also improve understanding, especially for non-Anglophone pilots who speak with heavy accents. The same systems could clean up the speech so that it is absolutely standard, with no missing or added words. Of course, the issue here is that the system would be stuck if it cannot recognize what is being said, or if a completely non-standard utterance is made by the pilot. A natural extension of this would be systems that recognize standard phrases in one language and translate them to another, but that would be even more dangerous if the system ever failed. Pilot: "Oh ****!" Electronically rephrased: "Mayday!" Still another idea is special training systems that listen to a pilot's speech and transcribe it, and point out any problems with understandability. Again, this would be most useful for non-Anglophone pilots, but it would work for anyone. If a machine can understand a pilot's speech clearly, then a human being should certainly be able to understand it that much more easily. I can understand you frustration with non-standard phraseology and foreign accents, but given the current state of the art, such a voice recognition/synthetic voice system as you suggest would probably be unworkable not to mention costly and short lived. I would expect to see data-link equipment (ACARS* or more likely ATN** or NEXCOM***) available for GA aircraft soon. * http://en.wikipedia.org/wiki/ACARS ** http://www.tc.faa.gov/act300/act350/ *** http://www.faa.gov/nextgen/nexcom/Publib/aboutnc2.htm |
#6
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Why don't voice radio communications use FM?
Mxsmanic wrote:
The reason I ask is that improper and misunderstood radio communication is a leading cause of accidents Really? Can you cite some statistics? I'd be very interested in reading them. |
#7
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Why don't voice radio communications use FM?
Yeah, Steve, it would. But I think we might be able to swap (on a long term
swap basis) the VHF com band for stuff up between 600 and 900 MHz. that have very limited usage. Not only could we get way more bandwidth, but the antenna size is cut by a factor of 6 or so. Jim "Steven P. McNicoll" wrote in message nk.net... "Mxsmanic" wrote in message news Perhaps this is a naive question, but: Why don't voice radio communications for aviation use FM radio instead of AM radio? Wouldn't that reduce the available frequencies? |
#8
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Why don't voice radio communications use FM?
"Mxsmanic" wrote in message ....that improper and misunderstood radio communication is a leading cause of accidents, Cite, please. ... I can barely understand what I hear on the radio. I suspect the reasons for this relate more to the environmental effects and quality of the speakers, etc., than to the nature of AM transmissions. |
#9
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Why don't voice radio communications use FM?
"James Robinson" wrote in message With AM, when two radios transmit on close frequencies, you either hear both signals poorly, or you get squeal, which is the sum of the two signals. This characteristic is considered important when you have elevated transmitters that can be hundreds of miles away, like on aircraft. Sounds plausible. Marine radios also operate in the VHF band, but are FM. They are also almost always at or very close to sea level. |
#10
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Why don't voice radio communications use FM?
Red herring, again. AM radio does the same suppression effect if the
signals are widely differing in power (google "AGC" or "AVC" for an explanation). The odds of two signals being absolutely equal in time is close to zero. True, they can start simultaneously, but the ending time is generally measured in multiseconds. One side or the other always gets the tag end of one conversation or the other and can figure out that a second station is trying to get a message across. The squeal when two nearly equal power signals is not the sum of the frequencies, it is the difference. Jim "James Robinson" wrote in message . .. Mxsmanic wrote: Perhaps this is a naive question, but: Why don't voice radio communications for aviation use FM radio instead of AM radio? I understand it is because of a characteristic of FM called "capture effect" that blanks out weaker transmissions when two radios transmit at the same time. The listener would have no idea that a second, weaker transmission was being made. With AM, when two radios transmit on close frequencies, you either hear both signals poorly, or you get squeal, which is the sum of the two signals. This characteristic is considered important when you have elevated transmitters that can be hundreds of miles away, like on aircraft. |
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