AMSAT-SM - Official Website of AMSAT-SM SwedenAO-40 is continuing to drift downward in ALON as predicted.
This is making the squint/range combination less favorable for passband use.
In addition, the solar angle is worsening and will shortly exceed 45 degs,limiting available power and warming the spacecraft considerably as the sun swings across the omni end of the spacecraft.
The AO-40 passbands will be turned off at MA=240 (23:50 UTC) on Saturday 4/19. They will remain off for about 4 weeks (or slightly less) until conditions improve.
– —W4SM for the AO-40 Command Team
Klla: amsat
Pictures taken today confirm that we have now reached ALON / ALAT = 51 / 20.
Magnetorquing has been turned off and we have begun
drifting down in ALON under the influence of the so-called mystery effect ( due to momentum wheel magnets interacting with earth s magnetic field ). Drift rate will
be approximately -18.2 degs / week at the current spin rate. This will place us on the other side of the sun in approximately 4 weeks, when we can decrease ALAT and begin chasing the sun back to 0/0.
The solar angles will begin increasing rapidly as we move backward and the passbands will be turned off within a few days until conditions improve. The beacon will remain on continuously.
– — W4SM for the AO-40 Command Team
Klla: amsat
Det har under en tid diskuterats om mjligheten att placera en transponder p mnen, jag publicerar ett inlgg frn en av dom ivrigaste fresprkarna.
73 Hkan SM7WSJ
—————–
Moon station or L1 satellite is not like EME !!
Hello,
The view of most amateurs on the path losses for a moon station or L1 orbit are not really true. For such large distances you don t need bigger stations than for EME ! An EME contact is completely different with a direct contact between the ground station and the satellite.
To give you some examples:
Path losses
EME: Direct (Earth -> moon-station) Difference
– ———————————————————-
70cm 261dB 197dB 64dB !!
3cm 289dB 225dB 64dB !!
Communication with a station on the moon can be done with common HAM equipment, like shown below:
On 70cm when both stations use 20W power and 13dB antennas:
– ———————————————————
Uplink 20W = +43dBm
Uplink ant. gain = +13db (medium yagi)
——————-
Uplink ERP = +56dBm
path losses = -197dB
———————
ERP on the moon = -141dB
Ant gain moon = +13dB (medium yagi)
———————
Moon reciever input = -128dBm
On 10GHz when both station use 10W power and 80cm dish ant. (36dB):
———————————————————–
Uplink 1W = +40dBm
Uplink 80cm dish = +36dB
———————–
Uplink ERP = +76dBm
path losses = -225dB
———————–
ERP on the moon = -149dBm
80cm dish moon = +36dB
———————–
Moon reciever input = -113dBm
These stations are not like EME station 🙂
When looking at L1 satellites with lets say 4x more distance the situation gets some more path losses but still possible for amateurs.
Path losses:
to Moon to L1 sat difference
70cm 197dB 199dB 12dB
10GHz 225dB 237dB 12dB
When both station increase their antenna gain by 6dB the same path conditions will stay. On 70cm the satellite can also use 6dB more power (80W), and the ground station can use an 16dB yagi instead of the 10dB yagi.
This is still within the common ham possibility.
On 10GHz the ground station can use a 1,5m dish instead of the 80cm, and the satellites power and antenna could be increased to overcome its 6dB. 🙂
This is all well within the normal amateur equipment, and still far below the needed EME equipment 🙂 What most
people think More away from the moon is more difficult than EME… is not always true 🙂
So, when do we start to build the first Moon station ? 🙂
73 de PE1RAH, William
Klla: PE1RAH
Nu finns det mjlighet fr dom som inte ftt upp sina satellitantenner att ven mta likasinnade ver ntet via (Voice)
mvh Hkan SM7WSJ
Announcing a new Internet service from AMSAT.ORG — an EchoLink conference server, *AMSAT*.
EchoLink is a Voice over IP system that lets amateur radio operators (only) talk to each other over theInternet. It can be used by individuals at their computers, or via simplex radio links, or through linked repeaters. It s very easy and fun! The software you need to communicate with EchoLink and more information about EchoLink are both available on the net.
A conference server allows many operators, links, and repeaters to share the same conversation. The new *AMSAT* conference server provides a place for satellite operators world-wide to congregate and chat. The server is up continuously. All amateurs are invited to
connect and give it a try.
73 -Paul
kb5mu@amsat.org
AMSAT VP, Electronic Publications
Klla: amsat
AO-40 Update, 2003-04-07
ALON/ALAT is now 45/3 degs. We are beginning to raise ALAT to 20 degs. This will take about a week. Once we are at ALON/ALAT = 45/20 and have verified this position, we will turn off the passband and magnetorquer, and begin drifting past the sun, toward ALON/ALAT ~ 315/20.
Depending on final spin rate, the drift should take approximately a month. Once we reach this ALON, we will lower ALAT to 0 and passband will be restored, moved to the early portion of the orbit. We will then begin chasing the sun back to ALON/ALAT = 0/0.
W4SM for the AO-40 Command Team
Klla: amsat