Re: [amsat-bb] ISS APRS Signal Quality? (tone skew?)
Im gonna take a stab with zero current knowledge.
Butover the years, one DIGI on ISS uses a radio and an external TNC with audio connections. The other digi on ISS used a Kenwood with internal TNC directly connected to the discriminator and modulator. One has a flat response and the other has the normal preemphasis and deemphasis.
So if one transmits tones that are inbalanced, then one system does better than the other. And in fact, with just a few dB of inbalance in the wrong direction, no amount of RF power will correct that. It simply will not decode.
You can hear this on terrestrial packet frequencies. Probably 80% of all the signals on the air "work" but have terribly misconfigured tones. People just hook'em'up and "it works" to the local digi, but they are not aware that it might not work at all in weak signal realm where tone settings must be ideal.
On my mobile, I see some signals that are dead full quieting with all signal bars that do not decode, and then I see another kenwood with only 3 bars and noisy that does just fine. Tone balance is exteremely critical.
Everyone should look at their tones on an oscope or at least listen to their tones compared to a good known signal. (Factory TNC in a k enwood). Though, when you listen to or look at "your " tones, the characteristics of the audio in that receiver can also have a skew.
And, do NOT look at them one at a time. That tells you nothing. Since the speech circuits will adjust them to the same level usually... Look at the relative amplitudes of the two. You can fix them with the right capacitor either in series to improve the high tone, or in parallel to diminish the high tone.
But the right cap must perfectly match the impedance of your particular set up.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Fernando Ramirez Sent: Tuesday, February 12, 2019 9:43 PM To: walterh@k5wh.net Cc: AMSAT -BB amsat-bb@amsat.org Subject: Re: [amsat-bb] ISS APRS Signal Quality?
I have tried two different radios, an Icom IC-2820h and a Kenwood TM-V71A. No luck with the Icom at full power on a high elevation pass. Better luck with the Kenwood but only on higher passes and transmitting with 50w.
Other operators have been able to get their packets digipeated with Kenwood APRS-Ready HTs, so it's kind of puzzling.
I'm using a Mobilinkd TNC3. I have no problem hitting distant terrestrial digipeaters with both setups.
73 Fernando, NP4JV
On Tue, Feb 12, 2019, 7:37 PM walterh@k5wh.net wrote:
I definitely have to agree with you.
The signal does seem to be less than half of what it used to be, and I have yet to hit it myself. When it used to be so easy.
Not sure what has changed, but it's certainly not the same as it was before the shut down several weeks ago.
Walter/K5WH
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Frank Karnauskas Sent: Tuesday, February 12, 2019 5:19 PM To: amsat-bb@amsat.org Subject: [amsat-bb] ISS APRS Signal Quality?
Is it me or does the APRS signal not sound as strong as it was before and is it not hearing quite as well?
I am having a heck of a time pinging the digipeater and the signal seems to be down a bit.
Could entirely be something on my end, but I would appreciate others' opinion.
73, Frank
FRANK W. KARNAUSKAS, N1UW N1UW@GOKARNS.com
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
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Bob, your guess would be more likely if the ground station was using an external TNC whereby the settings might have gotten mucked up somewhere along the way. But, I, for one, am using the same TH-D74 and the same TM-D710G I was using before. It's unlikely that both radios went weird at the same time.
I really wish the problem was on my end. It's a lot easier to fix things on the ground than it is up there!
73, Frank
FRANK W. KARNAUSKAS, N1UW N1UW@GOKARNS.com 612-644-9174
-----Original Message----- From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Robert Bruninga Sent: Wednesday, February 13, 2019 7:39 AM To: AMSAT -BB Subject: Re: [amsat-bb] ISS APRS Signal Quality? (tone skew?)
Im gonna take a stab with zero current knowledge.
Butover the years, one DIGI on ISS uses a radio and an external TNC with audio connections. The other digi on ISS used a Kenwood with internal TNC directly connected to the discriminator and modulator. One has a flat response and the other has the normal preemphasis and deemphasis.
So if one transmits tones that are inbalanced, then one system does better than the other. And in fact, with just a few dB of inbalance in the wrong direction, no amount of RF power will correct that. It simply will not decode.
You can hear this on terrestrial packet frequencies. Probably 80% of all the signals on the air "work" but have terribly misconfigured tones. People just hook'em'up and "it works" to the local digi, but they are not aware that it might not work at all in weak signal realm where tone settings must be ideal.
On my mobile, I see some signals that are dead full quieting with all signal bars that do not decode, and then I see another kenwood with only 3 bars and noisy that does just fine. Tone balance is exteremely critical.
Everyone should look at their tones on an oscope or at least listen to their tones compared to a good known signal. (Factory TNC in a k enwood). Though, when you listen to or look at "your " tones, the characteristics of the audio in that receiver can also have a skew.
And, do NOT look at them one at a time. That tells you nothing. Since the speech circuits will adjust them to the same level usually... Look at the relative amplitudes of the two. You can fix them with the right capacitor either in series to improve the high tone, or in parallel to diminish the high tone.
But the right cap must perfectly match the impedance of your particular set up.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Fernando Ramirez Sent: Tuesday, February 12, 2019 9:43 PM To: walterh@k5wh.net Cc: AMSAT -BB amsat-bb@amsat.org Subject: Re: [amsat-bb] ISS APRS Signal Quality?
I have tried two different radios, an Icom IC-2820h and a Kenwood TM-V71A. No luck with the Icom at full power on a high elevation pass. Better luck with the Kenwood but only on higher passes and transmitting with 50w.
Other operators have been able to get their packets digipeated with Kenwood APRS-Ready HTs, so it's kind of puzzling.
I'm using a Mobilinkd TNC3. I have no problem hitting distant terrestrial digipeaters with both setups.
73 Fernando, NP4JV
On Tue, Feb 12, 2019, 7:37 PM walterh@k5wh.net wrote:
I definitely have to agree with you.
The signal does seem to be less than half of what it used to be, and
I
have yet to hit it myself. When it used to be so easy.
Not sure what has changed, but it's certainly not the same as it was before the shut down several weeks ago.
Walter/K5WH
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Frank Karnauskas Sent: Tuesday, February 12, 2019 5:19 PM To: amsat-bb@amsat.org Subject: [amsat-bb] ISS APRS Signal Quality?
Is it me or does the APRS signal not sound as strong as it was
before
and is it not hearing quite as well?
I am having a heck of a time pinging the digipeater and the signal seems to be down a bit.
Could entirely be something on my end, but I would appreciate
others'
opinion.
73, Frank
FRANK W. KARNAUSKAS, N1UW N1UW@GOKARNS.com
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not
reflect
the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings:
http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not
reflect
the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings:
http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
I guess the fact that it is the same radio and just a new replacement TNC means that things should mostly be the same. But then again, nothing is ever exactly the same. Just the slightest difference in audio tone levels out of the new TNC could make a slight difference and for those who may have been on the good side of the "edge" might just get bumped over to the bad side of the edge.
It was only a theory. Thanks to Ken for clarifying what is new...
Back under my rock...
Bob
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Frank Karnauskas Sent: Wednesday, February 13, 2019 10:42 AM To: 'AMSAT -BB' amsat-bb@amsat.org Subject: Re: [amsat-bb] ISS APRS Signal Quality? (tone skew?)
Bob, your guess would be more likely if the ground station was using an external TNC whereby the settings might have gotten mucked up somewhere along the way. But, I, for one, am using the same TH-D74 and the same TM-D710G I was using before. It's unlikely that both radios went weird at the same time.
I really wish the problem was on my end. It's a lot easier to fix things on the ground than it is up there!
73, Frank
FRANK W. KARNAUSKAS, N1UW N1UW@GOKARNS.com 612-644-9174
-----Original Message----- From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Robert Bruninga Sent: Wednesday, February 13, 2019 7:39 AM To: AMSAT -BB Subject: Re: [amsat-bb] ISS APRS Signal Quality? (tone skew?)
Im gonna take a stab with zero current knowledge.
Butover the years, one DIGI on ISS uses a radio and an external TNC with audio connections. The other digi on ISS used a Kenwood with internal TNC directly connected to the discriminator and modulator. One has a flat response and the other has the normal preemphasis and deemphasis.
So if one transmits tones that are inbalanced, then one system does better than the other. And in fact, with just a few dB of inbalance in the wrong direction, no amount of RF power will correct that. It simply will not decode.
You can hear this on terrestrial packet frequencies. Probably 80% of all the signals on the air "work" but have terribly misconfigured tones. People just hook'em'up and "it works" to the local digi, but they are not aware that it might not work at all in weak signal realm where tone settings must be ideal.
On my mobile, I see some signals that are dead full quieting with all signal bars that do not decode, and then I see another kenwood with only 3 bars and noisy that does just fine. Tone balance is exteremely critical.
Everyone should look at their tones on an oscope or at least listen to their tones compared to a good known signal. (Factory TNC in a k enwood). Though, when you listen to or look at "your " tones, the characteristics of the audio in that receiver can also have a skew.
And, do NOT look at them one at a time. That tells you nothing. Since the speech circuits will adjust them to the same level usually... Look at the relative amplitudes of the two. You can fix them with the right capacitor either in series to improve the high tone, or in parallel to diminish the high tone.
But the right cap must perfectly match the impedance of your particular set up.
Bob, WB4aPR
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Fernando Ramirez Sent: Tuesday, February 12, 2019 9:43 PM To: walterh@k5wh.net Cc: AMSAT -BB amsat-bb@amsat.org Subject: Re: [amsat-bb] ISS APRS Signal Quality?
I have tried two different radios, an Icom IC-2820h and a Kenwood TM-V71A. No luck with the Icom at full power on a high elevation pass. Better luck with the Kenwood but only on higher passes and transmitting with 50w.
Other operators have been able to get their packets digipeated with Kenwood APRS-Ready HTs, so it's kind of puzzling.
I'm using a Mobilinkd TNC3. I have no problem hitting distant terrestrial digipeaters with both setups.
73 Fernando, NP4JV
On Tue, Feb 12, 2019, 7:37 PM walterh@k5wh.net wrote:
I definitely have to agree with you.
The signal does seem to be less than half of what it used to be, and
I
have yet to hit it myself. When it used to be so easy.
Not sure what has changed, but it's certainly not the same as it was before the shut down several weeks ago.
Walter/K5WH
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Frank Karnauskas Sent: Tuesday, February 12, 2019 5:19 PM To: amsat-bb@amsat.org Subject: [amsat-bb] ISS APRS Signal Quality?
Is it me or does the APRS signal not sound as strong as it was
before
and is it not hearing quite as well?
I am having a heck of a time pinging the digipeater and the signal seems to be down a bit.
Could entirely be something on my end, but I would appreciate
others'
opinion.
73, Frank
FRANK W. KARNAUSKAS, N1UW N1UW@GOKARNS.com
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not
reflect
the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings:
http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not
reflect
the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings:
http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (2)
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Frank Karnauskas -
Robert Bruninga