http://www.shreveporttimes.com/apps/pbcs.dll/article?AID=/20050113/NEWS/50113004 ----- Original Message ----- From: "Allan9" <exatc@xxxxxxxxxx> To: <AIRLINE@xxxxxxxxxxxxxxxxx> Sent: Saturday, January 15, 2005 10:25 AM Subject: Re: [Sky-1] Shreveport radio shut down due to RF interference > Gerry > Low end is 108 Mhz > TVOR's and ILS > Al > > ----- Original Message ----- > From: "Gerard M Foley" <gfoley@xxxxxxxxxxxxxxx> > To: <AIRLINE@xxxxxxxxxxxxxxxxx> > Sent: Saturday, January 15, 2005 10:03 AM > Subject: Re: [Sky-1] Shreveport radio shut down due to RF interference > > >> From: "Travel Pages" <travelpages@xxxxxxxxx> >> >> Sent: Friday, January 14, 2005 6:59 PM >> >> >>> That business of FM ending at the bottom of FAA radiowaves is exactly >>> the >>> issue still around today concerning the use of cellphones. >>> >>> Someone will know better than I, but in the 1960's I believe a TWA DC3 >>> hit >>> an AA DC4 in fog over the East River in New York --- authorities >>> allegedly >>> found in a child's carryon a radio in the ON position at the top of the >>> dial.... and that, I belive, was the beginning of the story about radios >>> mucking with nav equipment.... >>> >> Almost all radio receivers are superheterodynes, invented by Edward >> Armstrong. who also invented FM radio as it is used today. >> >> In a superheterodyne receiver the incoming desired signal is mixed with >> the >> output of a local oscillator, which is in effect a little radio >> transmitter. >> In many FM receivers, the local oscillator is on a frequency 10.7 MHz >> above >> that of the desired station. Thus when tuning in an FM station on a >> frequency of 101.3 MHz, the a frequency licensed for broadcasting in >> North >> America, the local oscillator frequency of such a set is 101.3+10.7=112 >> MHz, >> the low end of the aircraft band which covers 112-136MHz. Such a radio >> tuned to a station at 107.9 will have its oscillator running at >> 107.9+10.7=118.6, a frequency which might be used for a navaid. >> >> Thus the problem at Barksdale is probably not from the radio station per >> se, >> but from poorly shielded receivers close to the air base tuned to that >> station. >> >> Good receivers are shielded to prevent the local oscillator radiation >> from >> getting out, but many are not. >> >>> W Wilson <wlw-jr@xxxxxxx> wrote: >>> The radio station probably 'just' needs a tuning and a subsequent visit >>> from a "Flight check" aircraft to fly a series of approaches. >>> >> There is probably nothing wrong with the station. I don't know why the >> investigators are mystified, if my guess is correct. >> >> Gerry K8EF (Senior Member, IEEE) >> http://www.pbase.com/gfoley9999/ >> http://foley.ultinet.net/~gerry/aerial/aerial.html >> http://home.columbus.rr.com/gfoley >> http://www.fortunecity.com/victorian/pollock/263/egypt/egypt.html >> >