How you do DOPPLER correction in Linear Transponders?
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder 1) Adjust uplink and downlink automatic by CAT? (Not always woks, some times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
http://www.amsat.org/amsat/features/one_true_rule.html
If you can't do CAT, adjust the higher of the two frequencies used.
73, Drew KO4MA
----- Original Message ----- From: "Fabiano Moser" fabianomoser@gmail.com To: "amsat-bb" AMSAT-BB@amsat.org Sent: Thursday, July 02, 2009 12:19 PM Subject: [amsat-bb] How you do DOPPLER correction in Linear Transponders?
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder 1) Adjust uplink and downlink automatic by CAT? (Not always woks, some times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
The latest edition of "The ARRL Satellite Handbook" contradicts earlier versions, which suggested the same approach that Drew has here (i.e., always Doppler-tune the higher frequency) in favor of "parking" the uplink frequency and Doppler-tuning the downlink (see the section "Finding Yourself ... and Others," which begins on page 5-13 of the handbook). It occurs to me that, in general, that is the worst approach to take - although I admit to only knowing enough about all of this to be more dangerous than not.
Before I added computer-aided Doppler tuning to my station, I took Francesco's approach and always tried to stay at the same downlink frequency, Doppler-tuning the uplink regardless of whether it was the higher frequency. In reality, my approach is only inconsistent with Drew's ONLY on FO-29 because, on AO-7 (when in Mode B) and VO-52 (always in Mode B), the uplink IS the higher frequency.
The reason I believe the 2008 edition of "The ARRL Satellite Handbook" offers the worst approach has two elements:
1 - the "slipping" on the downlink that Francesco alludes to in his post, and
2 - the use of VO-52 as the "example satellite" for the description of how to find one's signal. The exercise directs readers to Doppler-tune the lower of the two frequencies to find themselves on the satellite.
Later today, I will try the "always tune the higher frequency" rule on FO-29, which I admittedly have not every tried. I'm looking forward to learning how that works for me since the higher frequency on that satelite is the downlink.
73 to all,
Tim - N3TL
-------------- Original message from Fabiano Moser fabianomoser@gmail.com: --------------
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder
- Adjust uplink and downlink automatic by CAT? (Not always woks, some times
I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
-- 73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
"There is no great talent without great will. (Honoré de Balzac)" _______________________________________________ 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
Tim, Fabiano and the BB,
This topic has been discussed for many decades.
Many approaches have valid logic, but there needs to be some recognized standard or multiple approaches will be used. Even with a standard, there are always new (and old) users that don't know about it, and thus don't follow it OR do know and choose not to follow it.
AMSAT adopted the 'One True Rule' decades ago and still stands by it.
There is a copy of 'One True Rule' and a description in the AMSAT "Getting Started Guide", and has been for years. 'One True Rule' needs a more visible link on the AMSAT web site, but that is another issue.
So, the official AMSAT line is to follow 'One True Rule' .
73, Gould, WA4SXM AMSAT VP Operations
----- Original Message ----- From: n3tl@bellsouth.net To: "Fabiano Moser" fabianomoser@gmail.com; "amsat-bb" AMSAT-BB@amsat.org Sent: Thursday, July 02, 2009 1:29 PM Subject: [amsat-bb] Re: How you do DOPPLER correction in Linear Transponders?
The latest edition of "The ARRL Satellite Handbook" contradicts earlier versions, which suggested the same approach that Drew has here (i.e., always Doppler-tune the higher frequency) in favor of "parking" the uplink frequency and Doppler-tuning the downlink (see the section "Finding Yourself ... and Others," which begins on page 5-13 of the handbook). It occurs to me that, in general, that is the worst approach to take - although I admit to only knowing enough about all of this to be more dangerous than not.
Before I added computer-aided Doppler tuning to my station, I took Francesco's approach and always tried to stay at the same downlink frequency, Doppler-tuning the uplink regardless of whether it was the higher frequency. In reality, my approach is only inconsistent with Drew's ONLY on FO-29 because, on AO-7 (when in Mode B) and VO-52 (always in Mode B), the uplink IS the higher frequency.
The reason I believe the 2008 edition of "The ARRL Satellite Handbook" offers the worst approach has two elements:
1 - the "slipping" on the downlink that Francesco alludes to in his post, and
2 - the use of VO-52 as the "example satellite" for the description of how to find one's signal. The exercise directs readers to Doppler-tune the lower of the two frequencies to find themselves on the satellite.
Later today, I will try the "always tune the higher frequency" rule on FO-29, which I admittedly have not every tried. I'm looking forward to learning how that works for me since the higher frequency on that satelite is the downlink.
73 to all,
Tim - N3TL
-------------- Original message from Fabiano Moser fabianomoser@gmail.com: --------------
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder
- Adjust uplink and downlink automatic by CAT? (Not always woks, some
times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
-- 73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
"There is no great talent without great will. (Honoré de Balzac)" _______________________________________________ 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
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
Fabiano,
You should if at all possible follow the One True Rule of Doppler tuning and tune both. If you tune both the uplink and the downlink, and the person with whom you are talking does the same, it makes the conversation much like a terrestrial HF communications. I often have a QSO from AOS to LOS on AO-7 and FO-29 without once tuning the radio manually. Most modern tracking programs, those written in the past 10 years, support this, and support the FT-847.
http://www.amsat.org/amsat/features/one_true_rule.html
Alan WA4SCA
----- Original Message ----- From: "Fabiano Moser" fabianomoser@gmail.com To: "amsat-bb" AMSAT-BB@amsat.org Sent: Thursday, July 02, 2009 6:19 PM Subject: [amsat-bb] How you do DOPPLER correction in Linear Transponders?
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder 1) Adjust uplink and downlink automatic by CAT? (Not always woks, some times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
-- 73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
Hi Fabiano, CR7/PY5RX
My preferred metod (from OSCAR-6 to AO40) is to adjust only the Uplink frequency in order to keep my voice in downlink as clear as possible exactly as you actually do manually. If the station in contact with me moves up or down I invite the operator to move the VFO of his TX to come again in my constant receiving frequency.
73" de i8CVS Domenico
Dear friends, Thank you very much for the answers, help me a lot and now I have better idea how operators does. Now I come back to other situation when I do doppler control automatic by Hamradiodeluxe:
Let make an example at VO-52 using middle of transponder. While the software is doing correction in the two VFO´s when I start to TX my signal are always above or below the frequency suggested by computer, and I need to put OFF uplink adjust at HRD and do by manual to go higher or lower in Uplink to listen my self. Okay I know the UHF doppler is higher than VHF, but I presume that HRD always adjust the better adjustment for UP and DOWN.
At FM satellites this not happen
This make me confused becuase if I have new kepler downloaded, why my audio always comes above or below the downlink who Hamradiodeluxe adjust on my FT-847.
73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
2009/7/2 i8cvs domenico.i8cvs@tin.it
----- Original Message ----- From: "Fabiano Moser" fabianomoser@gmail.com To: "amsat-bb" AMSAT-BB@amsat.org Sent: Thursday, July 02, 2009 6:19 PM Subject: [amsat-bb] How you do DOPPLER correction in Linear Transponders?
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder
- Adjust uplink and downlink automatic by CAT? (Not always woks, some
times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
--
Hi Fabiano, CR7/PY5RX
My preferred metod (from OSCAR-6 to AO40) is to adjust only the Uplink frequency in order to keep my voice in downlink as clear as possible exactly as you actually do manually. If the station in contact with me moves up or down I invite the operator to move the VFO of his TX to come again in my constant receiving frequency.
73" de i8CVS Domenico
----- Original Message ----- From: "Fabiano Moser" fabianomoser@gmail.com
This make me confused becuase if I have new kepler downloaded, why my audio always comes above or below the downlink who Hamradiodeluxe adjust on my FT-847.
HRD 5.0 is better - but in general you'll have to adjust the TX frequency using XIT as the transponder (and your radio) is usually not exactly on frequency.
With my TS-2000 on F_29 I have to TX 2.5kHz lower, to do this I use the XIT.
Simon Brown, HB9DRV www.ham-radio-deluxe.com
Fabiano,
FM reception is much less sensitive to slight frequency errors than SSB. Just because of the way it works, you can be a 2-3 KHz off frequency, and it will sound exactly the same.
On the other hand, if you have a good ear, you can hear errors of 20 Hz, and certainly 50-100 Hz with SSB. Now, consider that there are slight frequency shifts in the satellite transponders due to temperature changes, aging, etc. Also, the Keplerians are good approximations, but only approximations. As a result, you will need to make slight adjustments occasionally. I tune off to the end of the passband, give a quick test transmission while I talk myself on to the correct frequency, and that correction is good for the pass, and probably all the passes that day. SATPC32 and Ham Radio Deluxe both have ways to do this. The correction day to day is usually less than 100 Hz, and over a long time a few hundred Hz. Because of its lack of power regulation, AO-7 is particularly bad about this. After you have done it a couple of times, it only takes a few seconds, and makes operating much more pleasant for both you and the stations you talk with.
Alan WA4SCA
Fabiano,
Are you using the Beta version of Ham Radio Deluxe - v 4.1, Build 1989? That is the version I have installed. In it, the bottom "slider" on the right side of the tuning bar will enable you to fine-tune the uplink and downlink. The top slider allows you to use HRD to tune up and down the passband, and the offset will not change.
I hope this is helpful.
Note to all - I tried tuning the downlink on FO-29 last night. It seemed awkward at first because I'd only been tuning the uplink, regardless of whether it was the higher frequency. But literally after a minute or so, it was no problem.
73 to all,
Tim -------------- Original message from Fabiano Moser fabianomoser@gmail.com: --------------
Dear friends, Thank you very much for the answers, help me a lot and now I have better idea how operators does. Now I come back to other situation when I do doppler control automatic by Hamradiodeluxe:
Let make an example at VO-52 using middle of transponder. While the software is doing correction in the two VFO´s when I start to TX my signal are always above or below the frequency suggested by computer, and I need to put OFF uplink adjust at HRD and do by manual to go higher or lower in Uplink to listen my self. Okay I know the UHF doppler is higher than VHF, but I presume that HRD always adjust the better adjustment for UP and DOWN.
At FM satellites this not happen
This make me confused becuase if I have new kepler downloaded, why my audio always comes above or below the downlink who Hamradiodeluxe adjust on my FT-847.
73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
2009/7/2 i8cvs
----- Original Message ----- From: "Fabiano Moser" To: "amsat-bb" Sent: Thursday, July 02, 2009 6:19 PM Subject: [amsat-bb] How you do DOPPLER correction in Linear Transponders?
Dear friends,
We know that some Satellite Operators use diferent system to doppler control.
For Linear Transponder
- Adjust uplink and downlink automatic by CAT? (Not always woks, some
times I´m up or down from the computer adjust) 2) Adjust uplink and downlink manual 3) Keep Uplink fixed and adjust only the Downlink frequency.
What is the more indicate method to use? FT-847 have knob to adjust Uplink without change downlink VFO, and I´m using it to keep my voice in downlink at same downlink much I can.
But I know some operators use fixed uplink.
How you do?
--
Hi Fabiano, CR7/PY5RX
My preferred metod (from OSCAR-6 to AO40) is to adjust only the Uplink frequency in order to keep my voice in downlink as clear as possible exactly as you actually do manually. If the station in contact with me moves up or down I invite the operator to move the VFO of his TX to come again in my constant receiving frequency.
73" de i8CVS Domenico
-- 73 Fabiano Moser CR7/PY5RX ARISS-PORTUGAL (Amateur Radio on the International Space Station) Representative at Teleconference and Portugal Telebridge Coordinator. AMRAD/AMSAT-CT http://www.amrad.pt/ariss.php
"There is no great talent without great will. (Honoré de Balzac)" _______________________________________________ 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
participants (7)
-
Alan P. Biddle -
Andrew Glasbrenner -
Fabiano Moser -
Gould Smith -
i8cvs -
n3tl＠bellsouth.net -
Simon (HB9DRV)