Hi,
I few days ago now, ANDE-1 and RAFT were simultaneously visible from my QTH, and everyone else's too, I imagine.
Since both satellites Tx and Rx on 145.825 MHz, I wondered whether a dual hop is possible. However, it seems that the satellites are configured to prevent this. I wonder if there are any plans to try a dual hop - perhaps later when the satellites are near the end of their lives.
I presume too, that when they are in sight of each other, RAFT would been keeping ANDE awake. Is this true?
Sil - ZL2CIA
I few days ago now, ANDE-1 and RAFT were simultaneously visible from my QTH...
Since both satellites Tx and Rx on 145.825 MHz, I wondered whether a dual hop is possible. However, it seems that the satellites are configured to prevent this.
Actually, they are intentinoally on the same frequency and they are intended to be dual or even triple hop possible (when PCSAT-1 is working).. Notice that both satelites respond to the same path VIA ARISS. SO you could use the path VIA ARISS,ARISS and get a dual hop. This ia also why we invite any other university or amateur satellite builder to add more spacecraft on this 1200 baud relay channel (with IARU coordination of course).
In fact, it was the dual hop concept that was so exciting. And if you check the ANDE-RAFT OPS web page you will see several dual hops noted between PCSAT-1 and PCSAT2. The problem with ANDE and RAFT are their slightly worse link budgets. ANDE has no external antenna and uses the spacecraft as the antenna. It appears to be about 6 dB worse than PCSAT-1. And RAFT is such a small 5" cube satellite that the 2 meter antennas are less efficient (think HT on rubber duck). SO the chances of dual hops with these two are less when you realize that one satellite has to hear the other (and on the same channel as lots of 50W ground stations)...
HOWEVER, they are in the same orbital plane and every several weeks, RAFT passes right under ANDE. I think within only a few KM. SO dual hops are DEFINITELY possible but more rare than with PCSAT-1 and PCSAT2 which were over 2700 miles apart for our longest dual hop packet to date.
See: http://www.ew.usna.edu/~bruninga/ande-raft-ops.html
WB4APR, Bob
Actually, they are intentinoally on the same frequency and they are intended to be dual or even triple hop possible (when PCSAT-1 is working).. Notice that both satelites respond to the same path VIA ARISS. SO you could use the path VIA ARISS,ARISS and get a dual hop. This ia also why we invite any other university or amateur satellite builder to add more spacecraft on this 1200 baud relay channel (with IARU coordination of course).
Bob,
Thanks for your reply.
I have already tried "via APRSAT,APRSAT,SGATE a number of times, but so far without successs. I wasn't sure if this was an acceptable practice, so I had been discrete about it.
I have been previously successful once getting a dual hop between PCSAT-1 and the ISS (when it was operating on 145.825 MHz)
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
I use nothing more than a horizontally polarised 6 element beam. It's home built and that without any fancy tools. It's horizontally mounted and steerable in azimuth with a simple rotator. I mention this just to make the point that both are really pretty easy satellites to work with just a little more antenna.
Both satellites are very quiet down here and I very seldom see any other users. I end up gating my own packets. This does allow me to experiment since I'm not obstructing anyone else.
I'll persevere with further dual hop tests in the future now that I understand it's okay to do so.
I am of course aware of ANDE-1's rather finite power reserve and do keep that in mind.
Sil
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
Sil, Thanks for the report. Do not worry about ANDE usage. It is well below anticipated, so we are not woried about life. But this week both are entering night time prime-time in the northern hemisphere and so usage will increase.
Also, I do want your assessment of their links. My rig is 22 elements cross polarized on AZ/EL mount with 100W amp/preamp at base fed from 150' of coax. I have not changed it in years, since I get the same performance to a VHF DX beacon about 30 miles away...
BUT... 1) The preamp is not really a low noise one, just one of those in a 100W remote PA to overcome some coax loss. 2) I suspect my deviation setting could be tweaked...
My results are: 1) I cannot access RAFT below 20 degrees and never in the day (due to overvoltage) 2) I can decode RAFT above about 10 deg, and some times all the way to 1 deg if lucky 3) ANDE is also about 10 deg but sometimes lower.
If you get better performance, let me know, since I want to know how my performance is relative to other setups.. I measure performance relative to elevation angle, because that is a direct correlation to range.
Thanks Bob
-----Original Message----- From: Sil - ZL2CIA [mailto:zl2cia@amsat.org] Sent: Friday, March 30, 2007 12:16 AM To: bruninga@usna.edu; AMSAT Subject: Re: [amsat-bb] Dual Hop
Actually, they are intentinoally on the same frequency and
they
are intended to be dual or even triple hop possible (when PCSAT-1 is working).. Notice that both satelites respond to
the
same path VIA ARISS. SO you could use the path VIA
ARISS,ARISS
and get a dual hop. This ia also why we invite any other university or amateur satellite builder to add more
spacecraft
on this 1200 baud relay channel (with IARU coordination of course).
Bob,
Thanks for your reply.
I have already tried "via APRSAT,APRSAT,SGATE a number of times, but so far without successs. I wasn't sure if this was an acceptable practice, so I had been discrete about it.
I have been previously successful once getting a dual hop between PCSAT-1 and the ISS (when it was operating on 145.825 MHz)
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
I use nothing more than a horizontally polarised 6 element beam. It's home built and that without any fancy tools. It's horizontally mounted and steerable in azimuth with a simple rotator. I mention this just to make the point that both are really pretty easy satellites to work with just a little more antenna.
Both satellites are very quiet down here and I very seldom see any other users. I end up gating my own packets. This does allow me to experiment since I'm not obstructing anyone else.
I'll persevere with further dual hop tests in the future now that I understand it's okay to do so.
I am of course aware of ANDE-1's rather finite power reserve and do keep that in mind.
Sil
Bob,
Thanks for your reply. I had the chance to make another attempt at a dual hop this afternoon. While I could copy both satellite beacons, I was not successful in making a dual hop. I used the path "via ARISS ARISS SGATE". It was fun to see the interleaved beacons and digipeated messages appearing on my screen (copied traffic was s-gated).
Tellingly, only ANDE repeated my packets. Until now, almost all the passes I have worked have been in the evening and I have had no problems getting traffic through RAFT..
I haven't had the opportunity to work NO60 and NO61 in the past few days, family taking precedence.
However, I will make some careful observations over the next few days and provide an assessment for you.
Unfortunately, I don't have a great QTH for horizon satellite work. I live in a small valley on the side of one of this cities many hills and these raise my effective horizon.
Sil - ZL2CIA
Robert Bruninga wrote:
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
Sil, Thanks for the report. Do not worry about ANDE usage. It is well below anticipated, so we are not woried about life. But this week both are entering night time prime-time in the northern hemisphere and so usage will increase.
Also, I do want your assessment of their links. My rig is 22 elements cross polarized on AZ/EL mount with 100W amp/preamp at base fed from 150' of coax. I have not changed it in years, since I get the same performance to a VHF DX beacon about 30 miles away...
BUT... 1) The preamp is not really a low noise one, just one of those in a 100W remote PA to overcome some coax loss. 2) I suspect my deviation setting could be tweaked...
My results are:
- I cannot access RAFT below 20 degrees and never in the day
(due to overvoltage) 2) I can decode RAFT above about 10 deg, and some times all the way to 1 deg if lucky 3) ANDE is also about 10 deg but sometimes lower.
If you get better performance, let me know, since I want to know how my performance is relative to other setups.. I measure performance relative to elevation angle, because that is a direct correlation to range.
Thanks Bob
-----Original Message----- From: Sil - ZL2CIA [mailto:zl2cia@amsat.org] Sent: Friday, March 30, 2007 12:16 AM To: bruninga@usna.edu; AMSAT Subject: Re: [amsat-bb] Dual Hop
Actually, they are intentinoally on the same frequency and
they
are intended to be dual or even triple hop possible (when PCSAT-1 is working).. Notice that both satelites respond to
the
same path VIA ARISS. SO you could use the path VIA
ARISS,ARISS
and get a dual hop. This ia also why we invite any other university or amateur satellite builder to add more
spacecraft
on this 1200 baud relay channel (with IARU coordination of course).
Bob,
Thanks for your reply.
I have already tried "via APRSAT,APRSAT,SGATE a number of times, but so far without successs. I wasn't sure if this was an acceptable practice, so I had been discrete about it.
I have been previously successful once getting a dual hop between PCSAT-1 and the ISS (when it was operating on 145.825 MHz)
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
I use nothing more than a horizontally polarised 6 element beam. It's home built and that without any fancy tools. It's horizontally mounted and steerable in azimuth with a simple rotator. I mention this just to make the point that both are really pretty easy satellites to work with just a little more antenna.
Both satellites are very quiet down here and I very seldom see any other users. I end up gating my own packets. This does allow me to experiment since I'm not obstructing anyone else.
I'll persevere with further dual hop tests in the future now that I understand it's okay to do so.
I am of course aware of ANDE-1's rather finite power reserve and do keep that in mind.
Sil
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
Maybe RAFT got reset? If its telemetry packets are every 10 seconds, then it is still set for digipeat. If it has fallen back to 1 minute rate, then digi is disabled. Ill check... http://pcsat.aprs.org ...
Yep, it is at 1 minute rate and needs a reload...
Ill send out an announcement to all command stations.
Bob
-----Original Message----- From: Sil - ZL2CIA [mailto:zl2cia@amsat.org] Sent: Tuesday, April 03, 2007 3:18 AM To: bruninga@usna.edu Cc: 'AMSAT' Subject: Re: [amsat-bb] Re: Dual Hop
Bob,
Thanks for your reply. I had the chance to make another attempt at a dual hop this afternoon. While I could copy both satellite beacons, I was not successful in making a dual hop. I used the path "via ARISS ARISS SGATE". It was fun to see the interleaved beacons and digipeated messages appearing on my screen (copied traffic was s-gated).
Tellingly, only ANDE repeated my packets. Until now, almost all the passes I have worked have been in the evening and I have had no problems getting traffic through RAFT..
I haven't had the opportunity to work NO60 and NO61 in the past few days, family taking precedence.
However, I will make some careful observations over the next few days and provide an assessment for you.
Unfortunately, I don't have a great QTH for horizon satellite work. I live in a small valley on the side of one of this cities many hills and these raise my effective horizon.
Sil - ZL2CIA
Robert Bruninga wrote:
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
Sil, Thanks for the report. Do not worry about ANDE usage. It is well below
anticipated, so
we are not woried about life. But this week both are
entering
night time prime-time in the northern hemisphere and so
usage
will increase.
Also, I do want your assessment of their links. My rig is
22
elements cross polarized on AZ/EL mount with 100W amp/preamp
at
base fed from 150' of coax. I have not changed it in years, since I get the same performance to a VHF DX beacon about 30 miles away...
BUT... 1) The preamp is not really a low noise one, just one
of
those in a 100W remote PA to overcome some coax loss. 2) I suspect my deviation setting could be tweaked...
My results are:
- I cannot access RAFT below 20 degrees and never in the
day
(due to overvoltage) 2) I can decode RAFT above about 10 deg, and some times all
the
way to 1 deg if lucky 3) ANDE is also about 10 deg but sometimes lower.
If you get better performance, let me know, since I want to
know
how my performance is relative to other setups.. I measure performance relative to elevation angle, because that is a direct correlation to range.
Thanks Bob
-----Original Message----- From: Sil - ZL2CIA [mailto:zl2cia@amsat.org] Sent: Friday, March 30, 2007 12:16 AM To: bruninga@usna.edu; AMSAT Subject: Re: [amsat-bb] Dual Hop
Actually, they are intentinoally on the same frequency and
they
are intended to be dual or even triple hop possible (when PCSAT-1 is working).. Notice that both satelites respond
to
the
same path VIA ARISS. SO you could use the path VIA
ARISS,ARISS
and get a dual hop. This ia also why we invite any other university or amateur satellite builder to add more
spacecraft
on this 1200 baud relay channel (with IARU coordination of course).
Bob,
Thanks for your reply.
I have already tried "via APRSAT,APRSAT,SGATE a number of times, but so far without successs. I wasn't sure if this was an acceptable practice, so I had been discrete about it.
I have been previously successful once getting a dual hop between PCSAT-1 and the ISS (when it was operating on 145.825 MHz)
The ANDE & RAFT satellites maybe be a little difficult with simple omnidirectional antennas, but both are a breeze with just a little more antenna.
I use nothing more than a horizontally polarised 6 element beam. It's home built and that without any fancy tools. It's horizontally mounted and steerable in azimuth with a simple rotator. I mention this just to make the point that both are really pretty easy satellites to work with just a little more antenna.
Both satellites are very quiet down here and I very seldom see any other users. I end up gating my own packets. This does allow me to experiment since I'm not obstructing anyone else.
I'll persevere with further dual hop tests in the future now that I understand it's okay to do so.
I am of course aware of ANDE-1's rather finite power reserve and do keep that in mind.
Sil
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