Some Elmering requested for uplinking to ARISSAT-1
Hi everyone,
A few months ago I asked for help receiving the beacon on ARISSAT-1 and got a lot of helpful suggestions. It turns out that my biggest problem was trying to listen from inside the house. Moving the antenna outside was the key. Heaven only knows what my shingles are made of...I never expected a problem!
So now that I got pretty comfortable with receiving, it was time to step up from my little HT and get a somewhat more flexible and powerful rig. The only satellite rigs still on the market are the ICOM 9100 and the Kenwood TS-2000 family. I know about the birdies in the TS-2000, but I could not really afford the ICOM...maybe should have gone for a used 910 or something, but I did end up with a TS-2000.
I still have the Eggbeater omni/circularly polarized 2m antenna for the downlink, and it is working great! I get a nice strong signal from the FM beacon, and I'm able to hear people on the transponder. I also either picked up the CW beacon or someone using CW on the transponder. So anyway, the downlink is working fine.
Now for the uplink: I built myself a 70cm Parasitic Lindenblad per the plans of Tony, AA2TX. I have it outside about 10 feet up, and an SWR meter shows something reasonable (1.3ish) so I guess I did not totally mess it up. I can also hit the local repeater 5 miles away on fairly low power, etc. The Lindenblad should be circularly polarized with kind of a donut-shaped pattern (more gain toward the horizon where the bird is further away, less overhead where it is closer). But so far I have not been able to hear myself trying to contact ARISSAT.
Here is what I tried: I set the TS2000 to satellite mode, and set it up so I was transmitting in the middle of the transponder uplink band on USB. Then I started scanning through the downlink passband while transmitting ("W2BFJ, tuning") using the "RIT" control so that transmit frequency was not changing. I was listening with LSB. I heard another station weakly, but not myself.
Can someone comment on my method, both in terms of technical goodness and good operating practice? A couple specific questions: 1) Xmitting in the middle of the passband and just scanning, I should be able to at least briefly find myself without messing with doppler, right? I was planning to lock the receive and transmit frequencies (constant sum) once I found myself and follow the doppler by hand, but I never got to that step. 2) I'm right that the sidebands are inverted from receive to xmit, right? I think I would hear something even if that was wrong. 3) Finally, what about power? How much have you required for success on ARRISAT? I was running around 25W. I could boost up to as high as 50, but I can only diddle so many knobs in 5 or 10 minutes :-) 3) I know a beam would be better, but trying to reduce variables, and pointing is one of them. Besides, I'm inside in my shack! But has anyone successfully uplinked with an omni/circular? I can always remove the parasitic elements and end up with a center-fed dipole to remove the circularity. (Not sure how that would affect the impedance match...)
Thanks!
Burns, W2BFJ
Hi,
I would strongly recommend using software controlled Doppler correction. It should be considered state of the art to correct uplink and downlink in order to keep the signal at fixed frequency in the satellites passband.
Before PCs became affordable, the manual standard procedure was to keep the rx frequency fixed and tune the tx until you hear yourself. I find it quite a nightmare and too many people are still doing it that way, performing very badly most of the time. With up-to-date orbital elements and precisely synchronized PC clock I mostly manage to keep my downlink signal within the 200 Hz passband of the CW filter.
Your other points: - Circular polarization should be fine and provide a more stable signal. - The tranponder inverts, standard is to receive USB and transmit LSB - It is much easier to find yourself by transmitting CW, best is a series of dits using an automatic keyer - CW is anyway more efficient
One probably very important point is the missing UHF antenna on Arissat. I am using an FT-847, 50W and a 17el cross yagi, giving more than 1 KW ERP. I can hear myself fairly well, but not very stable. I hear the transponder noise floor very well, so the uplink seems to be the bottleneck. There are reports about successful contacts with omni antennas, but it is probably not easy. The bird is pretty deaf.
Did you try your setup on VO52? This is an easy one and 25W to the Lindenblad should work very well. I think even AO7 mode B is easier than Arissat and also FO29 (this one is mode J or V/U transponder).
Like you, I am pretty new to the subject. I learned a lot by writing my own software for automatic Doppler correction for the FT-847 and for Rotor control. I am using NOVA for tracking.
Good luck, Edgar DF2MZ
Am 02.11.2011 22:12, schrieb Burns Fisher:
Hi everyone,
A few months ago I asked for help receiving the beacon on ARISSAT-1 and got a lot of helpful suggestions. It turns out that my biggest problem was trying to listen from inside the house. Moving the antenna outside was the key. Heaven only knows what my shingles are made of...I never expected a problem!
So now that I got pretty comfortable with receiving, it was time to step up from my little HT and get a somewhat more flexible and powerful rig. The only satellite rigs still on the market are the ICOM 9100 and the Kenwood TS-2000 family. I know about the birdies in the TS-2000, but I could not really afford the ICOM...maybe should have gone for a used 910 or something, but I did end up with a TS-2000.
I still have the Eggbeater omni/circularly polarized 2m antenna for the downlink, and it is working great! I get a nice strong signal from the FM beacon, and I'm able to hear people on the transponder. I also either picked up the CW beacon or someone using CW on the transponder. So anyway, the downlink is working fine.
Now for the uplink: I built myself a 70cm Parasitic Lindenblad per the plans of Tony, AA2TX. I have it outside about 10 feet up, and an SWR meter shows something reasonable (1.3ish) so I guess I did not totally mess it up. I can also hit the local repeater 5 miles away on fairly low power, etc. The Lindenblad should be circularly polarized with kind of a donut-shaped pattern (more gain toward the horizon where the bird is further away, less overhead where it is closer). But so far I have not been able to hear myself trying to contact ARISSAT.
Here is what I tried: I set the TS2000 to satellite mode, and set it up so I was transmitting in the middle of the transponder uplink band on USB. Then I started scanning through the downlink passband while transmitting ("W2BFJ, tuning") using the "RIT" control so that transmit frequency was not changing. I was listening with LSB. I heard another station weakly, but not myself.
Can someone comment on my method, both in terms of technical goodness and good operating practice? A couple specific questions: 1) Xmitting in the middle of the passband and just scanning, I should be able to at least briefly find myself without messing with doppler, right? I was planning to lock the receive and transmit frequencies (constant sum) once I found myself and follow the doppler by hand, but I never got to that step. 2) I'm right that the sidebands are inverted from receive to xmit, right? I think I would hear something even if that was wrong. 3) Finally, what about power? How much have you required for success on ARRISAT? I was running around 25W. I could boost up to as high as 50, but I can only diddle so many knobs in 5 or 10 minutes :-) 3) I know a beam would be better, but trying to reduce variables, and pointing is one of them. Besides, I'm inside in my shack! But has anyone successfully uplinked with an omni/circular? I can always remove the parasitic elements and end up with a center-fed dipole to remove the circularity. (Not sure how that would affect the impedance match...)
Thanks!
Burns, W2BFJ _______________________________________________ Sent via AMSAT-BB@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
Hi Burns,
My 2 cents -- sounds like things are mostly okay (your recieving setup is obviously good if you can hear others in the transponder passband). The big factor that I can see is lack of gain on the uplink. I've successfully gotten into ARISSAT with my 5W QRP radio, but that's using a 13 dBd gain yagi. In theory the ERP of your 25W uplink isn't too far below that, so it would be worthwhile trying the 50W to see if that helps. That or switch to an antenna outside with some gain...
Other factors to consider are sometimes the sats transponder is off (so even if everything at your end is okay you won't hear your own signal, nor anyone elses). And the return signal varies greatly from pass to pass, depending (I think) on the relative orientation of the antenna stub.
Also be sure to try finding yourself on CW first .... SSB is often very difficult to copy on ARISSAT, much easier to start with CW and once you've found yourself switch over.
73! de Dave KB5WIA
Can someone comment on my method, both in terms of technical goodness and good operating practice? A couple specific questions: 1) Xmitting in the middle of the passband and just scanning, I should be able to at least briefly find myself without messing with doppler, right? I was planning to lock the receive and transmit frequencies (constant sum) once I found myself and follow the doppler by hand, but I never got to that step. 2) I'm right that the sidebands are inverted from receive to xmit, right? I think I would hear something even if that was wrong. 3) Finally, what about power? How much have you required for success on ARRISAT? I was running around 25W. I could boost up to as high as 50, but I can only diddle so many knobs in 5 or 10 minutes :-) 3) I know a beam would be better, but trying to reduce variables, and pointing is one of them. Besides, I'm inside in my shack! But has anyone successfully uplinked with an omni/circular? I can always remove the parasitic elements and end up with a center-fed dipole to remove the circularity. (Not sure how that would affect the impedance match...)
Thanks!
Burns, W2BFJ
Thanks Dave and everyone else who responded, both personally and on the board. To comment on a couple of comments: I certainly expect to hook up computer control of the doppler comp etc, but was trying to do it manually at first just to understand better. Re my problems inside: The shingles on the house are pretty new so are not embedded with guck. However, I expected them to be pretty neutral. Not so. But anyway, I've given up having antennas in my attic, and I'm outside now exclusively. Re power, using CW to match up. Ok, I'll try my full power out, and CW. Thanks for the ideas. Re other sats, beam, etc: Good ideas for sure; I wanted to eliminate variables, and since I can't mess up pointing with an omni, and I have received ARRISat easily, I figured ARRISat involved the fewest variables. But I'll try the other stuff too.
Thanks again to everyone! I'll let you know how I make out. In the meantime, I'd like to hear from anyone who has been successful with an omni or Lindenblad with 50W uplink.
Burns, W2BFJ
On Wed, Nov 2, 2011 at 6:49 PM, David Palmer KB5WIA kb5wia@amsat.orgwrote:
Hi Burns,
My 2 cents -- sounds like things are mostly okay (your recieving setup is obviously good if you can hear others in the transponder passband). The big factor that I can see is lack of gain on the uplink. I've successfully gotten into ARISSAT with my 5W QRP radio, but that's using a 13 dBd gain yagi. In theory the ERP of your 25W uplink isn't too far below that, so it would be worthwhile trying the 50W to see if that helps. That or switch to an antenna outside with some gain...
Other factors to consider are sometimes the sats transponder is off (so even if everything at your end is okay you won't hear your own signal, nor anyone elses). And the return signal varies greatly from pass to pass, depending (I think) on the relative orientation of the antenna stub.
Also be sure to try finding yourself on CW first .... SSB is often very difficult to copy on ARISSAT, much easier to start with CW and once you've found yourself switch over.
73! de Dave KB5WIA
Can someone comment on my method, both in terms of technical goodness and good operating practice? A couple specific questions: 1) Xmitting in
the
middle of the passband and just scanning, I should be able to at least briefly find myself without messing with doppler, right? I was planning
to
lock the receive and transmit frequencies (constant sum) once I found myself and follow the doppler by hand, but I never got to that step. 2) I'm right that the sidebands are inverted from receive to xmit, right? I think I would hear something even if that was wrong. 3) Finally, what about power? How much have you required for success on ARRISAT? I was running around 25W. I could boost up to as high as 50, but I can only diddle so many knobs in 5 or 10 minutes :-) 3) I know a beam would be better, but trying to reduce variables, and pointing is one of them. Besides, I'm inside in my shack! But has anyone successfully uplinked
with
an omni/circular? I can always remove the parasitic elements and end up with a center-fed dipole to remove the circularity. (Not sure how that would affect the impedance match...)
Thanks!
Burns, W2BFJ
participants (3)
-
Burns Fisher -
David Palmer KB5WIA -
DF2MZ