----- Original Message ----- From: "Sebastian" [email protected] To: "AMSAT BB" [email protected] Sent: Saturday, August 30, 2008 6:41 AM Subject: [amsat-bb] FO-29 users where are you?
It seems that most of the time when there is a pass in my area from FO-29, there are no users on the bird. FO-29 is an excellent & loud satellite, and it requires very little output power.
I just spent 10 minutes or so calling cq, and listening up and down the passband, and there is no one around. It gets boring listening to myself on the downlink! This is generally the case, no matter the time of day or night.
Please, those of you who have the equipment - FO-29 is alive and well, let's use it!
73 de W4AS Sebastian
Hi Sebastian, W4AS
Over Europe there are many users of FO-29 but all of them are equipped with low noise preamplifiers antenna mounted and good antennas.
By the way when FO-29 comes up at AOS it is very common to listen for many stations trying to get back for their own signals back and fort all over the pass-band without success because their receiving sensitivity is low.
Since the FO-29 sensitivity is very high only a very low EIRP is necessary to be translated with sufficient power for a decent QSO in SSB or CW provided that the ground station sensitivity is adeguate as well.
Quoting many succesfull ground stations using FO-29 over EU it is possible to state that for good operation all over the orbit from AOS to LOS a minimum ratio G/T = - 2 dB is necessary.
As an example:
Antenna gain G = 13 dBi = 20 in power factor Overall receiving Noise Figure = 0.45 dB equal to T= 31.6 kelvin
G/T = 20 / 31.6 = 0.63 and 10 log 0.63 = -2 dB 10
Another example:
In order to get about the same ratio G/T = - 2 dB and following the above formula we see that it is possible to use an antenna with G= 16 dBi = 40 in power ratio and a greater receiving system overall Noise Figure = 0.9 dB corresponding to T = 67 kelvin
And so on..........
Many years ago the recommended ratio G/T for every satellite was supplied by AMSAT
The above G/T = -2 dB for FO-29 has been experimentally derived knowing the working conditions of many succesful stations in QSO with me over Europe.
73" de
i8CVS Domenico