----- Original Message ----- From: "Hal Lund ZS6WB" [email protected] To: "I8CVS Dom" [email protected] Sent: Thursday, January 28, 2010 7:59 AM Subject: Heard on FO-29
Hello Dom
I just wanted to let you know that I heard you calling this morning on FO-29 at 0615 utc. You were on CW on a downlink of about 435.840 MHz. You were heard for several minutes and I copied your call distinctly several times.
You were probably transmitting on AO-7 at the time as AO-7 and FO-29 were very close together but AO-7 was just below a ridge to the west of me and I could not hear it directly at that time.
We could almost make it on AO-7 if my station wasn't sitting in a bit of a hole.
It appears that FO-29 has been operational for several hours continuously now so that looks very promising.
73 - Hal ZS6WB
Pretoria (KG44ee)
Hello Hal, ZS6WB and All on the List
Tank you very much for the above important information and I will try to explain you what was really happening this night/morning on day 28 jan at 06:15 UTC
Infact during orbit 61091 at 06:15 UTC I was transmitting to AO-07 around 432.158 MHz searching to be translated exactly on 145.940 MHz at the exact moment in wich AO-7 was at the very LOS for me with less than 0.3° elevation on South at the end of the descending orbit 61091 from North to South when AO-7 was about over ZS-land in South Africa and despite a few hills 20 km away over my horizon I received back my CW succesfully up to 0.3° elevation.
To determine my exact uplink frequency in order to be translated by AO-7 at 145.940 MHz +/- at the very AOS moment when the bird comes to me from South to North during an ascending orbit it was also very important for me this night because in the following days I plan to contact on skedule at 145.940 +/- MHz the friend ZS6BB, Pierre in KG43EU
But what was really happening this night ? You are right !
The distance into free space between AO-7 and FO-29 was about 1500 km at 06:15 UTC and both satellites where in mutual covisibility so that my 145.940 MHz CW signal that was translated by AO-7 was received by FO-29 and retranslated by FO-29 in 435.840 MHz at 06:15 UTC when you received my CW signal in Pretoria KG44EE through two satellites !
In more details at 06.15 UTC the subsatellite point (SSP) of AO7 was over Nigeria at 8.557° Latitude North and 10.095° Longitude Est and his footprint was not completely covering ZS land while the SSP of FO-29 was over Zaire at 6.482° Latitude South and Longitude 16.500° Est but his footprint was fully including ZS land where you was able to receive me in KG44EE
The above demonstrates that when the footprints of two satellites about overlaps a two way QSO between two satellites is possible particularly on CW provided that the uplink and downlink frequency bands are the same and one station transmit to one satellite in 70 cm listening in 2 meters while the other one transmit to the other satellite in 2 meters listening in 70 cm
Unfortunately this is not the case betwen AO-7 and FO-29 because the 70 cm bands are different 435.800 to 435.900 MHz for FO-29 and 432.125 to 432.175 MHz for AO-7 so that only one way two satellite link is possible as you Hal experienced because the same 2 meters band is in common between both satellites.
The above reception of my signal by you via FO-29 also demontrates that actually FO-29 is working very well after a very long QRT because it was so sensitive to receive my signal in 2 meters via AO-7 and retranslate it into 70 cm with sufficient power to be received by you in 70 cm in Pretoria South Africa
By the way since you in KG44EE are very close to Pierre in KG43EU I am confident the at the end of testing and try with Pierre via AO-7 I can try a QSO via AO-7 as well with you and I will informe you about if you agree.
The distance from my JN70ES and Pierre in KG43EU is 7548 km and with you in KG44EE is 7511 km both no bad distances from South Italy and South Africa via AO-7
Best 73" de
i8CVS Domenico