Dominico, Thank you very much for the calculations. It would seem that it is possible to work EME on the higher HF bands using WSJT modes under the right conditions. But, I can see that it would take an exceptional HF station to work CW on a regular basis. Of course there's the ionosphere to contend with as well.
Thanks again. Tony -K2MO On 6/30/2010 6:11 PM, i8cvs wrote: > ----- Original Message ----- > From: "Tony"<d...@optonline.net> > To: "AMSAT-BB"<amsat-bb@amsat.org>; "i8cvs"<domenico.i8...@tin.it> > Sent: Wednesday, June 30, 2010 10:31 AM > Subject: Re: [amsat-bb] Re: HF Satellite Relay > > >> Dominico, >> >> The 10M sphere brought another question to mind -- Mike Wantanabe, >> JH1KRC, managed to hear his own EME echoes on the 21MHz using a KW and a >> 6 element Yagi. Details and recordings are on his website (see below). I >> was wondering how the path loss calculations compare with his EME results. >> >> http://eme.dokidoki.ne.jp/sound/jh1krc/index.html >> >> Thanks Dominico... >> >> Tony -K2MO >> >> > Hi Tony, K2MO > > I have heard the EME echoes on the 21 MHz EME test from JH1KRC and they > are very strong for a 6 element yagi claiming 18 dBi at 10° elevation and 1 > KW output at the antenna but the moon was only 10.8° above the horizon for > JH1KRC so that he was advantaged by the gain of the ground at such low moon > elevation. > > By the way on day 14 jan 2006 the moon was at a distance of 400.000 km from > the earth and at a range of 405.000 km from JH1KRC so that the elapsed time > from TXing to the echoes must be ( 405.000 x 2 ) / 300.000 = 2.7 seconds and > this by hears seems to be accordingly. > > We know that the range from the Moon and JH1KRC was 405.000 km and we > know that the radius of the Moon is 1735 km or 1735 x 10^3 meters > Also we know that the reflectivity coefficient of the moon at 21 MHz is 7 % > > The 21 MHz Round Trip Isotropic Attenuation using the concept of Radar > Equation is as follows: > > Pt x Gt x Ar x Sigma > Pr = ------------------------------ > (4 x 3.14 x R^2)^2 > > where : > > Pr = received power > > Pt = transmitted power = 1watt > > Gt = gain of a 21 MHz isotropic antenna = 1 in power ratio > > Ar = Aperture of the isotropic antenna at 21 MHz in square meters. > > R = Radius of a sphere wich distance from the earth is 405 x 10^6 > meters i.e the distance from the Moon and the earth expressed > in meters. > > Sigma = Surface of the Moon in square meters i.e. of the Moon as a > radar target like a disc multiplied by the reflectivity > coefficient of 7 % > > Computing: > > / 2 2 > /\ 14.3 > Ar = ---------- = ----------- = 16.24 square meters > 4 x 3,14 4 x 3,14 > > > Sigma = (1735 x 10^3) ^2 x 3.14 x 0.07 = 6.62 x 10^11 square meters > > > > 1 x 1 x 16.24 x (6.62 x 10^11) > Pr = --------------------------------------- = 2.53 x 10^-24 watt > [(4 x 3.14 x ( 405 x 10^6)^2]^2 > > > 1 > Round trip attenuation = 10 log ----------------- = 236 dB > 2.53 x 10^-24 > > > Assuming that we are using a good HF receiver with a NF= 8 dB > equivalent to 1539 kelvin we must consider in addition that the receiver > sensitivity is limited by the external available noise power.For quiet,rural > locations as that of JH1KRC the galactic noise is the limiting factor and > at 21 MHz the noise temperature is around 29.000 kelvin so that reducing > the Noise Figure belove 8 dB at 21 MHz do not improve the S/N ratio. > > In addition during the 15mEME01 QRO test on CW JH1KRC claims to > have used a RX CW filter with a bandwidth of only 10 Hz as you can > read in his web page. > > http://eme.dokidoki.ne.jp/sound/jh1krc/index.html > > With the above data the noise floor of this receiver for CW into a > bandwidth of 10 Hz can be calculated as follows: > > Noise Floor = KTB = 1.38 x 10^-23 ( 1539 + 29.000 ) x 10 = - 173.7 dBW > or - 142.6 dBm > > Link budged calculation: > > > TX power 1000 watt.............................+30 dBW > TX Antenna gain....................................+18 dBi > ----------- > Transmitted EIRP .................................+48 dBW > Round trip attenuation 1500 km..........- 236 dB > ----------- > Received power Pr on isotropic > antenna on the earth ..............................-188 dBW > RX antenna gain....................................+ 18 dB > ----------- > Available power at RX input............... - 170 dBW > RX noise floor...................................... - 173.7 dBW > ----------- > Signal received with a S/N ratio.......... + 3.7 dB > > > So according with the above calculations the signal of JH1KRC is 3.7 dB > over the noise and so it is detectable very strong as recorded in the file > 15m01142006_31qro in the following web page. > > http://eme.dokidoki.ne.jp/sound/jh1krc/index.html > > In addition since the test was made with the Moon at a very low elevation > of 10.8° we must add to 3.7 dB at least 1 or 2 dB or more due to the gain > of the ground. > > Probably if a new test will be made at higher moon elevation the echoes > of file 15m01142006_31qro would be audible but not so spectacular. > > Best 73" de > > i8CVS Domenico > > > > > > > > __________ Information from ESET NOD32 Antivirus, version of virus signature > database 5241 (20100630) __________ > > The message was checked by ESET NOD32 Antivirus. > > http://www.eset.com > > > > > _______________________________________________ Sent via amsat...@amsat.org. 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