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CX2SA > SATDIG 11.05.19 07:13l 815 Lines 32640 Bytes #999 (0) @ WW
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From: CX2SA@CX2SA.SAL.URY.SOAM
To : SATDIG@WW
Today's Topics:
1. Re: What influences LEO propagation? (Hans BX2ABT)
2. non-doppler correction on linear sats (Hans BX2ABT)
3. Re: What influences LEO propagation? (Bob)
4. Re: What influences LEO propagation? (GEO Badger)
5. Re: non-doppler correction on linear sats (k6vug@?????????.????
6. Re: What influences LEO propagation? (Hans BX2ABT)
7. AMSAT Academy Registration Deadline TODAY at 23:59 UTC /
7:59pm EDT (Paul Stoetzer)
8. Re: What influences LEO propagation? (Chris Thompson)
9. DN01/02 GRIDLINE - 2019-05-13 - KI7UNJ (KI7UNJ Tucker)
10. suitable omni antenna for FM sats? (Ron VE8RT)
----------------------------------------------------------------------
Message: 1
Date: Thu, 9 May 2019 16:01:35 +0800
From: Hans BX2ABT <hans.bx2abt@???.?????.???>
To: GEO Badger <w3ab@?????.???>, amsat-bb@?????.???
Subject: Re: [amsat-bb] What influences LEO propagation?
Message-ID: <685b392a-7d58-2e79-6617-864db9e2a751@???.?????.???>
Content-Type: text/plain; charset=utf-8; format=flowed
Well, I know VHF/UHF propagation and I know satellites are
line-of-sight, but how about signals from outer space trying to traverse
the ionosphere and atmosphere? Es makes terrestrial signals bounce back,
but does it also make space signals bounce back into space? Or at least
degrade them? You say "think horizontal" but space communications are
also partly horizontal if you take low elevation into consideration. I
feel there is more to this, but so far haven't found any info on this.
73 de Hans
BX2ABT
On 05/09/2019 05:53 AM, GEO Badger wrote:
> Hans,
>
> What I believe you are really asking is what effects VHF/UHF
> propagation. Lighting up a bird is a line of sight connection, not
> propagation in the classic sense of bouncing off the ionosphere and
> ground like in HF comms. But, there are atmospheric phenoms that can
> effect VHF/UHF comms. Tropo ducting, but that is normally for
> terrestrial comms. Same for sporadic E, which is bouncing signals off
> of ionized clouds similar to the ionosphere propagation..Think
> horizontal.
>
> Then there is weather. Whether or not you have nice weather. Rain,
> snow, clouds and dust are a few of the things that can effect sat comms.
>
> ---
> Ciao baby, catch you on the flip side.
> GEO
>
> http://www.w3ab.org
>
> Time flies like an arrow, fruit flies like a banana.
>
>
> On Wednesday, May 8, 2019, 7:12:57 AM PDT, Hans BX2ABT via AMSAT-BB
> <amsat-bb@?????.???> wrote:
>
>
> The last couple of days the Fox birds haven't been coming in as well as
> before. Signal strengths are down, fading has increased and it is almost
> impossible for me to open them. Now the sporadic E season also has
> kicked off in the last few days, with increased activity here in east
> Asia. Is this a coincidence or do the two have a connection? And are
> there other factors that influence LEO propagation? I know satellite
> tumbling is one factor that causes fades, but are there also ionospheric
> or atmospheric influences? Thanks for the insight. 73 de Hans (BX2ABT)
> _______________________________________________
> Sent via AMSAT-BB@?????.???. <mailto:AMSAT-BB@?????.???.> 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: https://www.amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 2
Date: Thu, 9 May 2019 16:07:37 +0800
From: Hans BX2ABT <hans.bx2abt@???.?????.???>
To: amsat-bb@?????.???
Subject: [amsat-bb] non-doppler correction on linear sats
Message-ID: <a2c35c2a-24cf-0139-b6e5-2baa599c3468@???.?????.???>
Content-Type: text/plain; charset=utf-8; format=flowed
How to deal with signals (CW/SSB) where the other party doesn't seem to
do doppler correction? I use an Airspy/IC820H combo to receive (2m) and
transmit (70cm) and both are controlled by Gpredict so that uplink and
downlink on linear sats stay in tune. However, I hear many stations that
apparently don't do this and their signals "walk" up very fast, right
out of my passband. Difficult to get their call, let alone have a QSO.
So what should be my strategy to deal with this?
73 de Hans
BX2ABT
------------------------------
Message: 3
Date: Thu, 9 May 2019 13:11:46 -0400
From: Bob <WB4SON@?????.???>
To: AMSAT-BB <amsat-bb@?????.???>
Subject: Re: [amsat-bb] What influences LEO propagation?
Message-ID:
<CAPonRZ-h638OzOFZCE3Mhjuh5PNih4ogu4tdSP9iKBE-9zhzEw@????.?????.???>
Content-Type: text/plain; charset="UTF-8"
Taiwan lies within the northern edge of the Equatorial Scintillation Zone
which is an area near the magnetic equator that suffers significant signal
attenuation even at VHF (and more so at UHF an up). It is more pronounced
during periods of high solar activity. In the past couple of weeks we have
been having some mild geomagnetic disturbances caused by coronal holes, and
more recently an earth-effective sunspot. Normally we think in terms of HF
impacts, but it will have big impact on space communication if you are on
one side of that scintillation zone and the satellite is on the other --
forcing the signal to cross through that area. Best I've read indicates
you can anticipate another 20 dB of signal loss on 70 cm. That might be
the difference between a signal that sounds great and one that is below the
noise level.
As many others have stated you also have weather influences, especially on
the 70 cm band, that will happen due to what is going on in the Troposphere.
73, Bob, WB4SON
On Thu, May 9, 2019 at 4:03 AM Hans BX2ABT via AMSAT-BB <amsat-bb@?????.???>
wrote:
> Well, I know VHF/UHF propagation and I know satellites are
> line-of-sight, but how about signals from outer space trying to traverse
> the ionosphere and atmosphere? Es makes terrestrial signals bounce back,
> but does it also make space signals bounce back into space? Or at least
> degrade them? You say "think horizontal" but space communications are
> also partly horizontal if you take low elevation into consideration. I
> feel there is more to this, but so far haven't found any info on this.
>
> 73 de Hans
>
> BX2ABT
>
>
> On 05/09/2019 05:53 AM, GEO Badger wrote:
> > Hans,
> >
> > What I believe you are really asking is what effects VHF/UHF
> > propagation. Lighting up a bird is a line of sight connection, not
> > propagation in the classic sense of bouncing off the ionosphere and
> > ground like in HF comms. But, there are atmospheric phenoms that can
> > effect VHF/UHF comms. Tropo ducting, but that is normally for
> > terrestrial comms. Same for sporadic E, which is bouncing signals off
> > of ionized clouds similar to the ionosphere propagation..Think
> > horizontal.
> >
> > Then there is weather. Whether or not you have nice weather. Rain,
> > snow, clouds and dust are a few of the things that can effect sat comms.
> >
> > ---
> > Ciao baby, catch you on the flip side.
> > GEO
> >
> > http://www.w3ab.org
> >
> > Time flies like an arrow, fruit flies like a banana.
> >
> >
> > On Wednesday, May 8, 2019, 7:12:57 AM PDT, Hans BX2ABT via AMSAT-BB
> > <amsat-bb@?????.???> wrote:
> >
> >
> > The last couple of days the Fox birds haven't been coming in as well as
> > before. Signal strengths are down, fading has increased and it is almost
> > impossible for me to open them. Now the sporadic E season also has
> > kicked off in the last few days, with increased activity here in east
> > Asia. Is this a coincidence or do the two have a connection? And are
> > there other factors that influence LEO propagation? I know satellite
> > tumbling is one factor that causes fades, but are there also ionospheric
> > or atmospheric influences? Thanks for the insight. 73 de Hans (BX2ABT)
> > _______________________________________________
> > Sent via AMSAT-BB@?????.???. <mailto:AMSAT-BB@?????.???.> 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
> _______________________________________________
> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 4
Date: Thu, 9 May 2019 17:23:40 +0000 (UTC)
From: GEO Badger <w3ab@?????.???>
To: AMSAT-BB <amsat-bb@?????.???>, Bob <WB4SON@?????.???>
Subject: Re: [amsat-bb] What influences LEO propagation?
Message-ID: <1675811667.3906788.1557422620488@????.?????.???>
Content-Type: text/plain; charset=UTF-8
Bob,
Thanks for bringing that up. I had forgotten about that effect, mostly
because I don't do radio near the equator. =!8^}
Here is a pdf discussing VHF/UHF atmospheric losses due to weather. Lots of
math.https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.370-7-199510-W!!PDF-E.
pdf
---?
Ciao baby, catch you on the flip side. ??
GEO ???
http://www.w3ab.org
Time flies like an arrow, fruit flies like a banana.
On Thursday, May 9, 2019, 10:14:13 AM PDT, Bob via AMSAT-BB
<amsat-bb@?????.???> wrote:
Taiwan lies within the northern edge of the Equatorial Scintillation Zone
which is an area near the magnetic equator that suffers significant signal
attenuation even at VHF (and more so at UHF an up).? It is more pronounced
during periods of high solar activity.? In the past couple of weeks we have
been having some mild geomagnetic disturbances caused by coronal holes, and
more recently an earth-effective sunspot.? Normally we think in terms of HF
impacts, but it will have big impact on space communication if you are on
one side of that scintillation zone and the satellite is on the other --
forcing the signal to cross through that area.? Best I've read indicates
you can anticipate another 20 dB of signal loss on 70 cm.? That might be
the difference between a signal that sounds great and one that is below the
noise level.
As many others have stated you also have weather influences, especially on
the 70 cm band, that will happen due to what is going on in the Troposphere.
73, Bob, WB4SON
On Thu, May 9, 2019 at 4:03 AM Hans BX2ABT via AMSAT-BB <amsat-bb@?????.???>
wrote:
> Well, I know VHF/UHF propagation and I know satellites are
> line-of-sight, but how about signals from outer space trying to traverse
> the ionosphere and atmosphere? Es makes terrestrial signals bounce back,
> but does it also make space signals bounce back into space? Or at least
> degrade them? You say "think horizontal" but space communications are
> also partly horizontal if you take low elevation into consideration. I
> feel there is more to this, but so far haven't found any info on this.
>
> 73 de Hans
>
> BX2ABT
>
>
> On 05/09/2019 05:53 AM, GEO Badger wrote:
> > Hans,
> >
> > What I believe you are really asking is what effects VHF/UHF
> > propagation. Lighting up a bird is a line of sight connection, not
> > propagation in the classic sense of bouncing off the ionosphere and
> > ground like in HF comms. But, there are atmospheric phenoms that can
> > effect VHF/UHF comms. Tropo ducting, but that is normally for
> > terrestrial comms. Same for sporadic E, which is bouncing signals off
> > of ionized clouds similar to the ionosphere propagation..Think
> > horizontal.
> >
> > Then there is weather. Whether or not you have nice weather. Rain,
> > snow, clouds and dust are a few of the things that can effect sat comms.
> >
> > ---
> > Ciao baby, catch you on the flip side.
> > GEO
> >
> > http://www.w3ab.org
> >
> > Time flies like an arrow, fruit flies like a banana.
> >
> >
> > On Wednesday, May 8, 2019, 7:12:57 AM PDT, Hans BX2ABT via AMSAT-BB
> > <amsat-bb@?????.???> wrote:
> >
> >
> > The last couple of days the Fox birds haven't been coming in as well as
> > before. Signal strengths are down, fading has increased and it is almost
> > impossible for me to open them. Now the sporadic E season also has
> > kicked off in the last few days, with increased activity here in east
> > Asia. Is this a coincidence or do the two have a connection? And are
> > there other factors that influence LEO propagation? I know satellite
> > tumbling is one factor that causes fades, but are there also ionospheric
> > or atmospheric influences? Thanks for the insight. 73 de Hans (BX2ABT)
> > _______________________________________________
> > Sent via AMSAT-BB@?????.???. <mailto:AMSAT-BB@?????.???.> 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
> _______________________________________________
> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
_______________________________________________
Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 5
Date: Thu, 9 May 2019 18:50:11 +0000 (UTC)
From: "k6vug@?????????.???? <k6vug@?????????.???>
To: amsat-bb@?????.???? Hans BX2ABT <hans.bx2abt@???.?????.???>
Subject: Re: [amsat-bb] non-doppler correction on linear sats
Message-ID: <1868920150.3958243.1557427811654@????.?????.???>
Content-Type: text/plain; charset=UTF-8
Hans,
The funny thing is that if both stations don't auto-correct for doppler they
can stay in QSO for much longer since both will "walk" the satellite's pass
band.? I guess this is how it worked in the good old days.?
?
So, when I faced this situation, I would tune to the calling station then
turn OFF my auto-correction and adjust only the uplink slightly to hear
myself when transmitting.? It worked in most cases.? If the calling station
puts out a very short CQ, like in FM sats, just TX and ask them to do a
longer call.?
?
?
GL es 73!
Umesh, k6vug
?
?
On Thursday, May 9, 2019, 1:08:16 AM PDT, Hans BX2ABT via AMSAT-BB
<amsat-bb@?????.???> wrote:
How to deal with signals (CW/SSB) where the other party doesn't seem to
do doppler correction? I use an Airspy/IC820H combo to receive (2m) and
transmit (70cm) and both are controlled by Gpredict so that uplink and
downlink on linear sats stay in tune. However, I hear many stations that
apparently don't do this and their signals "walk" up very fast, right
out of my passband. Difficult to get their call, let alone have a QSO.
So what should be my strategy to deal with this?
73 de Hans
BX2ABT
------------------------------
Message: 6
Date: Fri, 10 May 2019 20:19:04 +0800
From: Hans BX2ABT <hans.bx2abt@???.?????.???>
To: amsat-bb@?????.???
Subject: Re: [amsat-bb] What influences LEO propagation?
Message-ID: <0a4afc4b-1ba0-2487-2c9c-b59ab2cf9c34@???.?????.???>
Content-Type: text/plain; charset=utf-8; format=flowed
Wow, first time I've heard about this and it explains very well what
I've been seeing lately. Especially the deep, fast fading on many of the
AO-91/92/95 passes. I found this page that explains the basics of
equatorial scintillation: https://www.sws.bom.gov.au/Satellite/6/3.
Fascinating stuff, but on the other hand it makes my ham life in Taiwan
a bit more complicated. Also found this white paper, but I haven't read
it yet:
http://web.stanford.edu/group/scpnt/gpslab/website_files/sbas-ion_wg/sbas_iono
_scintillations_white_paper.pdf.
What I do get is that a lot of it is about scintillation on GPS
frequencies and the L-band. The bands we use are a lot lower, but still
suffer some influence.
Thank you Bob, lots to read this weekend.
Hans
BX2ABT
On 05/10/2019 01:11 AM, Bob via AMSAT-BB wrote:
> Taiwan lies within the northern edge of the Equatorial Scintillation Zone
> which is an area near the magnetic equator that suffers significant signal
> attenuation even at VHF (and more so at UHF an up). It is more pronounced
> during periods of high solar activity. In the past couple of weeks we have
> been having some mild geomagnetic disturbances caused by coronal holes, and
> more recently an earth-effective sunspot. Normally we think in terms of HF
> impacts, but it will have big impact on space communication if you are on
> one side of that scintillation zone and the satellite is on the other --
> forcing the signal to cross through that area. Best I've read indicates
> you can anticipate another 20 dB of signal loss on 70 cm. That might be
> the difference between a signal that sounds great and one that is below the
> noise level.
>
> As many others have stated you also have weather influences, especially on
> the 70 cm band, that will happen due to what is going on in the Troposphere.
>
> 73, Bob, WB4SON
>
> On Thu, May 9, 2019 at 4:03 AM Hans BX2ABT via AMSAT-BB <amsat-bb@?????.???>
> wrote:
>
>> Well, I know VHF/UHF propagation and I know satellites are
>> line-of-sight, but how about signals from outer space trying to traverse
>> the ionosphere and atmosphere? Es makes terrestrial signals bounce back,
>> but does it also make space signals bounce back into space? Or at least
>> degrade them? You say "think horizontal" but space communications are
>> also partly horizontal if you take low elevation into consideration. I
>> feel there is more to this, but so far haven't found any info on this.
>>
>> 73 de Hans
>>
>> BX2ABT
>>
>>
>> On 05/09/2019 05:53 AM, GEO Badger wrote:
>>> Hans,
>>>
>>> What I believe you are really asking is what effects VHF/UHF
>>> propagation. Lighting up a bird is a line of sight connection, not
>>> propagation in the classic sense of bouncing off the ionosphere and
>>> ground like in HF comms. But, there are atmospheric phenoms that can
>>> effect VHF/UHF comms. Tropo ducting, but that is normally for
>>> terrestrial comms. Same for sporadic E, which is bouncing signals off
>>> of ionized clouds similar to the ionosphere propagation..Think
>>> horizontal.
>>>
>>> Then there is weather. Whether or not you have nice weather. Rain,
>>> snow, clouds and dust are a few of the things that can effect sat comms.
>>>
>>> ---
>>> Ciao baby, catch you on the flip side.
>>> GEO
>>>
>>> http://www.w3ab.org
>>>
>>> Time flies like an arrow, fruit flies like a banana.
>>>
>>>
>>> On Wednesday, May 8, 2019, 7:12:57 AM PDT, Hans BX2ABT via AMSAT-BB
>>> <amsat-bb@?????.???> wrote:
>>>
>>>
>>> The last couple of days the Fox birds haven't been coming in as well as
>>> before. Signal strengths are down, fading has increased and it is almost
>>> impossible for me to open them. Now the sporadic E season also has
>>> kicked off in the last few days, with increased activity here in east
>>> Asia. Is this a coincidence or do the two have a connection? And are
>>> there other factors that influence LEO propagation? I know satellite
>>> tumbling is one factor that causes fades, but are there also ionospheric
>>> or atmospheric influences? Thanks for the insight. 73 de Hans (BX2ABT)
>>> _______________________________________________
>>> Sent via AMSAT-BB@?????.???. <mailto:AMSAT-BB@?????.???.> 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>> _______________________________________________
>> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>>
> _______________________________________________
> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
>
>
------------------------------
Message: 7
Date: Fri, 10 May 2019 08:25:31 -0400
From: Paul Stoetzer <n8hm@????.???>
To: AMSAT BB <amsat-bb@?????.???>
Subject: [amsat-bb] AMSAT Academy Registration Deadline TODAY at 23:59
UTC / 7:59pm EDT
Message-ID:
<CABzOSOoZOw0qWb7T0=JWroXUDP4W_G2v3Y_LV+HD=+9F89gRaw@????.?????.???>
Content-Type: text/plain; charset="UTF-8"
Don't miss out on the AMSAT Academy to be held on Thursday, May 16th,
9am-5pm at the DARA Clubhouse. Registration deadline is TODAY at 23:59
UTC / 7:59pm EDT.
https://www.amsat.org/other-events/amsat-activities-at-hamvention-2019/
And don't forget - the deadline for the TAPR/AMSAT Banquet is Tuesday,
May 14th at 22:00 UTC / 6:00pm EDT.
73,
Paul, N8HM
------------------------------
Message: 8
Date: Fri, 10 May 2019 12:21:58 -0400
From: Chris Thompson <chrisethompson@?????.???>
To: Hans BX2ABT <hans.bx2abt@???.?????.???>
Cc: AMSAT <AMSAT-BB@?????.???>
Subject: Re: [amsat-bb] What influences LEO propagation?
Message-ID:
<CAJOf0+smtw52GPP_TbP4PX7=7iN3nChinXwxAFeGk5U2FvNRiw@????.?????.???>
Content-Type: text/plain; charset="UTF-8"
Hans,
We get two different effects from the tumbling. First the polarization
changes as the antennae rotate because they have linear polarization. You
can minimize that impact if you have circular polarization on the ground.
Second the antenna pattern is rotating and it has nulls which may pass over
your station. Depending on the speed of rotation they might prevent you
opening the transponder. They definitely impact telemetry reception.
One thing to note is if telemetry is being received. If you can see the
RSSI and there are no other stations in the footprint then you can
sometimes see the received signal strength from your station. Have FoxTelem
plot the graph real time and see what effect transmitting has. If the sat
is receiving you but not being opened then perhaps the tone is not being
decoded correctly due to peaks and nulls from the rotation.
73
Chris
On Fri, May 10, 2019, 08:20 Hans BX2ABT via AMSAT-BB <amsat-bb@?????.???>
wrote:
> Wow, first time I've heard about this and it explains very well what
> I've been seeing lately. Especially the deep, fast fading on many of the
> AO-91/92/95 passes. I found this page that explains the basics of
> equatorial scintillation: https://www.sws.bom.gov.au/Satellite/6/3.
> Fascinating stuff, but on the other hand it makes my ham life in Taiwan
> a bit more complicated. Also found this white paper, but I haven't read
> it yet:
>
>
http://web.stanford.edu/group/scpnt/gpslab/website_files/sbas-ion_wg/sbas_iono
_scintillations_white_paper.pdf.
>
> What I do get is that a lot of it is about scintillation on GPS
> frequencies and the L-band. The bands we use are a lot lower, but still
> suffer some influence.
>
> Thank you Bob, lots to read this weekend.
>
> Hans
>
> BX2ABT
>
>
> On 05/10/2019 01:11 AM, Bob via AMSAT-BB wrote:
> > Taiwan lies within the northern edge of the Equatorial Scintillation Zone
> > which is an area near the magnetic equator that suffers significant
> signal
> > attenuation even at VHF (and more so at UHF an up). It is more
> pronounced
> > during periods of high solar activity. In the past couple of weeks we
> have
> > been having some mild geomagnetic disturbances caused by coronal holes,
> and
> > more recently an earth-effective sunspot. Normally we think in terms of
> HF
> > impacts, but it will have big impact on space communication if you are on
> > one side of that scintillation zone and the satellite is on the other --
> > forcing the signal to cross through that area. Best I've read indicates
> > you can anticipate another 20 dB of signal loss on 70 cm. That might be
> > the difference between a signal that sounds great and one that is below
> the
> > noise level.
> >
> > As many others have stated you also have weather influences, especially
> on
> > the 70 cm band, that will happen due to what is going on in the
> Troposphere.
> >
> > 73, Bob, WB4SON
> >
> > On Thu, May 9, 2019 at 4:03 AM Hans BX2ABT via AMSAT-BB <
> amsat-bb@?????.???>
> > wrote:
> >
> >> Well, I know VHF/UHF propagation and I know satellites are
> >> line-of-sight, but how about signals from outer space trying to traverse
> >> the ionosphere and atmosphere? Es makes terrestrial signals bounce back,
> >> but does it also make space signals bounce back into space? Or at least
> >> degrade them? You say "think horizontal" but space communications are
> >> also partly horizontal if you take low elevation into consideration. I
> >> feel there is more to this, but so far haven't found any info on this.
> >>
> >> 73 de Hans
> >>
> >> BX2ABT
> >>
> >>
> >> On 05/09/2019 05:53 AM, GEO Badger wrote:
> >>> Hans,
> >>>
> >>> What I believe you are really asking is what effects VHF/UHF
> >>> propagation. Lighting up a bird is a line of sight connection, not
> >>> propagation in the classic sense of bouncing off the ionosphere and
> >>> ground like in HF comms. But, there are atmospheric phenoms that can
> >>> effect VHF/UHF comms. Tropo ducting, but that is normally for
> >>> terrestrial comms. Same for sporadic E, which is bouncing signals off
> >>> of ionized clouds similar to the ionosphere propagation..Think
> >>> horizontal.
> >>>
> >>> Then there is weather. Whether or not you have nice weather. Rain,
> >>> snow, clouds and dust are a few of the things that can effect sat
> comms.
> >>>
> >>> ---
> >>> Ciao baby, catch you on the flip side.
> >>> GEO
> >>>
> >>> http://www.w3ab.org
> >>>
> >>> Time flies like an arrow, fruit flies like a banana.
> >>>
> >>>
> >>> On Wednesday, May 8, 2019, 7:12:57 AM PDT, Hans BX2ABT via AMSAT-BB
> >>> <amsat-bb@?????.???> wrote:
> >>>
> >>>
> >>> The last couple of days the Fox birds haven't been coming in as well as
> >>> before. Signal strengths are down, fading has increased and it is
> almost
> >>> impossible for me to open them. Now the sporadic E season also has
> >>> kicked off in the last few days, with increased activity here in east
> >>> Asia. Is this a coincidence or do the two have a connection? And are
> >>> there other factors that influence LEO propagation? I know satellite
> >>> tumbling is one factor that causes fades, but are there also
> ionospheric
> >>> or atmospheric influences? Thanks for the insight. 73 de Hans (BX2ABT)
> >>> _______________________________________________
> >>> Sent via AMSAT-BB@?????.???. <mailto:AMSAT-BB@?????.???.> 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: https://www.amsat.org/mailman/listinfo/amsat-bb
> >> _______________________________________________
> >> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
> >>
> > _______________________________________________
> > Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
> >
> >
> >
>
> _______________________________________________
> Sent via AMSAT-BB@?????.???. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 9
Date: Fri, 10 May 2019 13:08:47 -0700
From: KI7UNJ Tucker <ki7unj@?????.???>
To: AMSAT BB <amsat-bb@?????.???>
Subject: [amsat-bb] DN01/02 GRIDLINE - 2019-05-13 - KI7UNJ
Message-ID:
<CAPFr_Uk2On+12Xk9xjr2qC0JUQoPHiLaZSo3hdnBWEt6sf4bEg@????.?????.???>
Content-Type: text/plain; charset="UTF-8"
Will be on the DN01/DN02 Gridline on Monday, May 13th
FM Passes Only.
AO-92 - 2019-05-13 17:20:05Z (+10 min 59 seconds)
AO-91 - 2019-05-13 17:40:28Z (+9 min 44 seconds)
AO-92 - 2019-05-13 18:53:19Z (+11 min 2 seconds)
AO-91 - 2019-05-13 19:12:58Z (+14 min 10 seconds)
Track me on APRS https://t.co/JZc3nbDywp
Use DN02HA for Satmatch.com FP predictions
--
Casey Tucker KI7UNJ
https://twitter.com/KI7UNJ
https://www.qrz.com/db/KI7UNJ
http://bit.do/ki7unj
<https://www.google.com/url?q=http://bit.do/ki7unj&sa=D&source=hangouts&ust=15
21073499558000&usg=AFQjCNFcQLn6C9nmmvpQiBbD6XvN-QjKug>
------------------------------
Message: 10
Date: Fri, 10 May 2019 23:00:04 -0600
From: Ron VE8RT <ve8rt@?????.??>
To: amsat-bb@?????.???
Subject: [amsat-bb] suitable omni antenna for FM sats?
Message-ID: <20190510230004.d0f929e1075897a62827d8f0@?????.??>
Content-Type: text/plain; charset=US-ASCII
We have a newly licenced amateur in DP79. Because they fell a few
points of getting their Basic with Honours they do not have HF
privileges, their only way to communicate with the outside world is via
satellite. Anticipating this possible outcome, that they may not get
access to the HF bands, I sent them a hard copy, (no home internet, and
its slow and expensive there if you do have it), of the current copy of
"Getting Started with Amateur Satellites". As we're heading into the
time of year to do any outside work, the most pressing question is what
is the best compromise antenna for a base station. Keeping in mind
their location, in order to work anyone they'll have to get into the
satellites while the satellite is close to their horizon, otherwise the
satellite footprint will not cover areas with any satellite operators.
Ron VE8RT in DP22
--
Ron VE8RT <ve8rt@?????.??>
------------------------------
Subject: Digest Footer
_______________________________________________
Sent via amsat-bb@?????.???.
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 member? Join now to support the amateur satellite program!
https://www.amsat.org/mailman/listinfo/amsat-bb
------------------------------
End of AMSAT-BB Digest, Vol 14, Issue 187
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