Was this sent out on april 1st? The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com
On 4/10/2010 9:20 PM, i8cvs wrote: > Hi All, > > The specifications of the Arecibo Observatory Amateur Radio Club > for the 432 MHz Moon Bounce test on April 16-17 and 18 are as > follows: > > Dish diameter: 1000 foot equivalent to 305 meters > Antenna gain: 60 dBi > Tx power: 400 W > Tx Frequency: 432.045 MHz > > Since the given ERP is 243,902,443 Million Watts (see below) > and since 60 dB is equivalent to 1000000 (one Million) time in > power it comes out that the power reaching the feed of the dish is: > > 243902443 / 1000000 = 243 watt > > The rest of the power 400-243 = 157 watt is lost in the feed line. > > At 432 MHz a dish with a diameter of 305 meters has a -3dB points > main lobe angle equal to: > > Theta = Lambda / Diameter = 0.69 / 305 = 0.00227 rad. > > The above lobe of the dish at an average distance of 380000 km > light up a small circular surface S over the moon wich diameter is: > > D = 380000 x 0.00227 = 865 km > > The surface area S = (3.14 x 865^2) / 4 = 5.88 x 10^11 square meters > > All the radiated power of 243 watt by the dish is now collected over > the above S area. > > The reflectivity of the moon at 432 MHz is the 7% so that the power > scattered back isotropically by the moon is ( 243/100 ) x 7 = 17 watt > > It is like to say that the power reflected back by the moon is 17 watt > feeding an isoptropic antenna or 17 watt EIRP or +12 dBW EIRP > radiated isotropically by the moon. > > Since the surface of the moon lighed up by the dish is less then the whole > surface of the moon the usual calculation procedure for the EME link > considering the isotropic attenuation earth-moon-earth cannot be used > here because as seen by the Arecibo dish the diameter of the moon is > smaller than in reality and is large only 865 km in diameter not 3476 km > as is large in reality the moon. > > With this is mind we must imagine the dish of Arecibo to be an isotropic > antenna with 17 watt applied to it and transmitting all around isotropically > from the moon. > > My ground antenna has a gain G= 15 dBi and an antenna picked up noise > of 70 kelvin when looking at the cold sky > > My receiving system at 432 MHz has an overall Noise Figure of 0.7 dB > equivalent to 50 kelvin so that the noise floor KTB of my receiving system > in SSB with a bandwidth of 2400 Hz is > > KTB=1,38 x 10^-23 x (50 + 70) x 2400=3.97x10^-18 watt= -174 dBW > > LINK BUDGED CALCULATION: > > Isotropic power reflected by the moon...+12 dBW > Isotropic attenuation for 380.000 Km.. - 197 dB > ------- > Power received on isotropic earth ant... - 185 dBW > Ground antenna gain...............................+ 15 dBi > ------- > Power applied to ground receiver..........- 170 dBW > Noise floor of ground receiver..............- 174 dBW > ------- > Received Signal to Noise ratio S/N.......+ 4 dB > > By the way when KP4AO will operate on CW I can switch on the 500 Hz > filter on my receiver and here I will gain in sensitivity 2400/500 = 4.8 > time and 10 log 4.8 = 6.8 dB so that I gain 4 + 6.8 = 10.8 dB of overall > 10 > Signal to Noise ratio > > If I can stake two 70 cm antennas with gain 15 dBi each I can gain about > another 3 dB and I can improve the S/N ratio to 10.8 + 3 = 13.8 dB > > If I can stack four 70 cm antennas with gain 15 dBi each I can gain about > another 3 dB and I can improve the S/N ratio up to 13.8 + 3 = 16.8 dB > a real very strong signal on CW or 16.8 - 6.8 = 10 dB in SSB Signal to > Noise ratio wich is considered to be optimal for a comfortable reception > in SSB > > By the way to work EME using a big dish having a lobe with an aperture > angle "theta" smaller than the diameter subtended by the moon wich > is about 0.5 degrees i.e. 0.0087 radiants is useful only for the big dish to > hear better those stations using smaller dishes but the big dish to be > received better by the smaller one's "must" use more power and not increase > the diameter of the dish because as soon as the moon is completely resolved > the power scattered back isotropically do not increase increasing the > diameter of the dish. > > In conclusion I believe that ground stations with an antenna gain of 15 dBi > and a receiving system with an overall Noise Figure of about 1 dB can easily > hear KP4AO on CW and barely in the noise on SSB > > Stations with the same receiver overall Noise Figure and antenna gain from > 18 to 21 dB can hear KP4AO on CW and SSB without problems. > > Stations using 100 watt or more and the above antennas ranging from 15 dBi > to 21 dBi have chance to make QSO with KP4AO on CW > > The above calculation shows that it is very difficult to hear KP4AO or be > heard using a small hand-held yagi pointed at the moon. > > Have fun > > 73" de > > i8CVS Domenico > > ----- Original Message ----- > From: "MM"<ka1...@yahoo.com> > To:<amsat-bb@amsat.org> > Sent: Wednesday, April 07, 2010 3:06 PM > Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce > > > >> Hi all: >> Here is a EME event you cant miss. >> Dust off your CW key, its time for Satellite, QRP EME. >> >> The 1,000 foot dish has 60 dBi on 432 mc and 400 watts. >> That comes out to be approximately 243,902,443 Million Watts ERP. >> >> enjoy >> >> wf1f >> www.marexgm.org >> >> (thanks to KB1MGI for passing on this data) >> >> >> Arecibo on 432 MHz Moon Bounce >> >> The Arecibo Observatory Amateur Radio Club will be putting the >> 1000-foot radio telescope on the air for 432 MHz EME from April 16-18. >> >> It can be heard with a small hand-held yagi pointed at the moon >> >> The scheduled times of operation are: >> >> April 16: 1645 - 1930 UTC >> >> April 17: 1740 - 2020 UTC >> >> April 18: 1840 - 2125 UTC >> >> Callsign: KP4AO >> >> Tx Frequency: 432.045 MHz >> >> Rx Frequency: 432.050 to 432.060+ >> >> Tx power: 400 W >> >> Antenna gain: 60 dBi >> >> System noise temp: 120 K (cold sky) >> >> System noise temp: 330 K (when pointed at moon) >> >> KP4AO can be heard with a small hand-held yagi pointed at the moon and a >> good receiver. A 15 dBi antenna and 100 W will be enough to work us on >> CW. >> >> Operators at KP4AO will do their best to work as many stations as >> possible. Each session will start with a brief announcement and CQ in >> SSB. SSB QSOs may continue for 30 minutes to an hour, if the QSO rate >> remains high. >> >> The mode will be shifted to CW as soon as it is judged that higher QSO >> rates would result. >> >> We will listen for calls at frequencies 5-15 kHz higher than our own, >> and even higher if QRM warrants. Callers who s-p-r-e-a-d o-u-t are more >> likely to be copied. >> >> If you've already worked us in any mode, please do not call again -- >> give others a chance. >> >> If we call "CQ QRP", we will listen for stations running 100 W or less >> to a single yagi. Please do not answer such a CQ if you are running more >> power or have a larger antenna. >> >> On April 18, if we reach a condition where most calling stations have >> been worked, and we judge that operating in the digital mode JT65B would >> produce a higher QSO rate, we will switch to JT65B. >> >> Note that any of these planned operating strategies may be changed as >> circumstances dictate. >> >> We are extremely fortunate to have been granted access to the world's >> largest radio telescope for this amateur radio good-will event. We look >> forward to working as many stations as possible in the alloted time! >> >> > From QRZ.COM >> >> KB1MGI >> >> Moon-Net Email reflector >> >> http://list- serv.davidv. net/mailman/ ...erv.davidv. net >> >> Moon Bounce information >> >> http://www.vhfdx. info/eme. html >> >> UK Ham makes EME contact with just 25 watts >> >> http://www.southgat earc.org/ news/jan. ..me_contact. htm >> >> Earth-Moon-Earth with 20 Watts >> >> http://www.southgat earc.org/ news/jan. ..h_20_watts. htm >> >> WSJT Software for EME >> >> http://www.physics. princeton. edu/pulsar/ K1JT/ >> >> >> >> _______________________________________________ >> Sent via amsat...@amsat.org. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> > > > > _______________________________________________ > Sent via amsat...@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > > _______________________________________________ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
