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CX2SA > SATDIG 17.06.16 10:10l 806 Lines 31765 Bytes #999 (0) @ WW
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To : SATDIG@WW
Today's Topics:
1. Re: RTL-SDR downlink (Jim Barbre)
2. Re: RTL-SDR downlink (Patrick STODDARD (WD9EWK/VA7EWK))
3. Re: RTL-SDR downlink (Eduardo PY2RN)
4. Re: "Only Half of the CubeSats Deployed into Space Work"
(Cass Hussmann)
5. Re: Only Half of the CubeSats Deployed into Space Work
(Daniel Schultz)
6. Re: Only Half of the CubeSats Deployed into Space Work
(Peter Laws)
7. Re: Only Half of the CubeSats Deployed into Space Work
(Arthur Feller)
8. Re: Only Half of the CubeSats Deployed into Space Work (B J)
9. Re: RTL-SDR downlink (Rico van Genugten)
10. Re: Only Half of the CubeSats Deployed into Space Work (M5AKA)
----------------------------------------------------------------------
Message: 1
Date: Thu, 16 Jun 2016 14:27:29 -0700
From: Jim Barbre <jbarbre@xxxxxxxx.xxx>
To: amsat-bb@xxxxx.xxx
Subject: Re: [amsat-bb] RTL-SDR downlink
Message-ID: <576319C1.7060705@xxxxxxxx.xxx>
Content-Type: text/plain; charset=windows-1252; format=flowed
The Airspy Mini sells for $114. Worth looking into.
73
Jim Barbre
KB7YSY
On 6/16/2016 1:22 PM, Patrick STODDARD (WD9EWK/VA7EWK) wrote:
> Hi, (name or call?)!
>
> The inexpensive RTL-SDR dongles are a great way to get started with
> SDR receivers. For amateur satellite work, other than the ISS and maybe
> AO-85, they have a couple of significant drawbacks...
>
> 1. These dongles were designed to be TV receivers, working with
> signals much stronger than we have from our satellites or even the
> ISS ham station.
>
> 2. These dongles lack front-end filtering. This means that there could
> be a strong signal near you that swamps the receiver that wipes out
> what you're trying to hear. If you are trying to work satellites
> full-duplex, it is possible that your transmitter will shut down
> the dongle until you end your transmission. This was a problem I
> experienced early on when I tried using one of these dongles as
> my downlink receiver, and quickly moved on to something else.
>
> Unfortunately there isn't anything in the middle ground between these
> dongles and devices like the SDRplay (sold by HRO in the US for $149)
> or the FUNcube Dongle Pro+ (sold by its UK manufacturer for around
> $200 depending on exchange rates, which includes FedEx next-day
> shipping from England to most addresses in the continental USA). Both
> of these devices do well as the downlink receiver for working
> satellites. Both come with front-end filtering that the RTL-SDR
> dongles lack, and still have sensitive receivers. The SDRplay
> has a low-noise amplifier that is engaged when receiving at VHF or
> higher, but you can reduce the amount of gain from the built-in LNA.
> For my work, I keep that gain reduction value set to 0, so I have
> maximum gain to hear the downlinks.
>
> Good luck, and 73!
>
>
>
>
>
> Patrick WD9EWK/VA7EWK
> http://www.wd9ewk.net/
> Twitter: @xxxxxx
>
>
>
>
>
>
------------------------------
Message: 2
Date: Thu, 16 Jun 2016 22:36:34 +0000
From: "Patrick STODDARD (WD9EWK/VA7EWK)" <amsat-bb@xxxxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] RTL-SDR downlink
Message-ID:
<CAN6TEUc=SekxW=W008Kwj9xBm8zPJF_=ij7QN9e8-YoKjGZb7g@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Hi Peter!
You are correct. The inexpensive RTL-SDR dongles are a great way to
give SDR a try. With the low prices, there should also be appropriate
expectations. Since these were originally made as television
receivers, they were designed for use with stronger signals than
what we typically see from our satellites. Can they work as a
downlink receiver? Sure. Just like a Baofeng HT can be used to
work FM satellites. Not the best thing, but they can work.
I've tried a few of these devices as downlink receivers for working
satellites. In my case, these receivers need to be able to handle
nearby RF on a different band, which is a problem for some of these
devices. My list of devices I have tried are:
1. RTL-SDR dongles. No front-end filtering, not as sensitive as
other devices, they shut down in the presence of 5W or less when I
am transmitting to a satellite. Even as little as 500mW can be a
problem for these devices. I might have spent more time using these
if I only wanted to receive. Also, I would like to have something that
didn't require an upconverter to cover the HF spectrum above 24
MHz. I keep one plugged into a PC at my office, and use that to
listen to FM stations and occasionally the local fire or state
trooper dispatch channels (still in analog around Phoenix).
2. FUNcube Dongle Pro (not the Pro+). A better receiver than the
RTL-SDRs, but also lacking front-end filtering. No good for me as
part of my satellite station, but could have been fine for receive-only
setups.
3. FUNcube Dongle Pro+. Nice receiver, has front-end filtering
including SAW filters at 2m and 70cm, directly compatible with the
FUNcube Dashboard and FoxTelem programs. Only drawback for me is the
192 kHz maximum bandwidth. The 240-420 MHz frequency gap is not a
big deal, but is for some who like hearing the military aircraft or
satellites in this range.
4. HackRF. This is a wideband transceiver, covering from around 100
kHz to 6 GHz, with a maximum bandwidth of 20 MHz. It is nice to use
one of these to watch the entire FM broadcast band, but its receiver
really isn't up to the task as a downlink receiver for our current
satellites at 10m (AO-7 mode A), 2m, or 70cm. I have the Great Scott
Gadgets HackRF One and the crowdfunded HackRF Blue version. Other
than the crowdfunded version using some different components and
costing about $100 less, the HackRF Blue functions the same as
the HackRF One. The HackRF devices lack front-end filtering,
and come with warnings about using them in the presence of strong RF,
so I have not tried using one of these along with an FT-817 or
HT to work satellites, but its receive-only performance is not
impressive.
5. SDRplay. This is what I have been using for satellite work for
the past year. With 100 kHz-2 GHz unblocked, maximum 8 MHz bandwidth,
and bandpass filtering across that range, it has worked very well for
me - even in Los Angeles. I use this with an 8-inch Windows 10
tablet and HDSDR software, which is a low-overhead program that does
fine on these low-end tablets. FUNcube Dashboard and FoxTelem
cannot directly use an SDRplay, but with something like HDSDR and
a virtual audio cable I can make use of the SDRplay with those
programs. Or I can make RF recordings of the passes in HDSDR, then
play back the recording later through a virtual audio cable into
those programs to decode telemetry.
I have not tried either the Airspy or Airspy Mini. These units do
not cover below 24 MHz, and require an upconverter if you want to use
them for HF reception, but they will cover the bands currently used
for our satellites, starting at 10m and going up. There is a US-based
distributor for Airspy, so you don't have to order these from
overseas.
Of course, your location will determine how much interference you
will have to withstand. I didn't have that to deal with at a recent
demonstration I gave in Long Beach earlier this year, when I used my
SDRplay and tablet as the downlink receiver to work a couple of the
XW-2 satellites. I don't have those issues at my house here in the
Phoenix area, and have yet to run into a place where there is a lot
of interference to deal with. I have used my SDRplay/HDSDR combination
from many locations across the US and Canada in the past year, and
have yet to run into a situation where the local RF swamps my SDRplay.
SDRplays are sold at HRO in the US for $149. FUNcube Dongle Pro+
is sold by its UK manufacturer, and including FedEx shipping to
the US runs around $200 depending on exchange rates. The HackRF One is
available for around $300. I have 3 SDRplays, two that go with me for
demonstrations or presentations, and one as a backup. I also have a
couple of FUNcube Dongle Pro+ receivers, which will eventually
be used for an unattended receive-only setup at home with the FUNcube
Dashboard and FoxTelem programs on a PC.
I would recommend either the FUNcube Dongle Pro+ or SDRplay if you are
wanting to work satellites using one of these receivers for the
downlink side of your station. If you want to see some examples of
what I have received using my SDRplays, I have lots of RF recordings
at http://dropbox.wd9ewk.net/ - look for the folders with YYYYMMDD
dates at the start of the file names, followed by the satellite name
and the grid I operated from. You are welcome to download them and
run them through HDSDR or some other SDR software. And, yes, there
is a lot of data up in that Dropbox space. :-)
73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
Twitter: @xxxxxx
On Thu, Jun 16, 2016 at 8:33 PM, Peter Laws <plaws0@xxxxx.xxx> wrote:
>
> The $20 versions are well worth the effort if you've never played with
> an SDR of any sort before. For satellite downlinks? Dunno, never
> tried. Surely as you describe!
>
> Has anyone done any kind of "shoot out" comparing the cheapos to the
> real ones or even between the real ones (FCD, SDRPlay)? Before I
> plunk down $200, I'd like to see what I'm getting ... over and above
> what my $20 dongle can do, of course. :-) I read what you typed, but
> I'd like to see numbers.
>
>
>
------------------------------
Message: 3
Date: Thu, 16 Jun 2016 23:08:36 +0000 (UTC)
From: Eduardo PY2RN <py2rn@xxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] RTL-SDR downlink
Message-ID:
<137946933.4525092.1466118516999.JavaMail.yahoo@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
The cheap RTL dongles are as much sensible (or more) than the others more
expensive.Lack of filtering is the big issue although there are some
practical and easy workarounds to improve it.For ham satellites downlink
frequency stability should not be an big issue, there are some models
already been sold? with 0.5PPM TCXO option which are still cheap.It is a
great opportunity to operate full-duplex on amateur satellites with very low
investment and improving operational capabilities.
EME (Moon bounce) audible signal RX comparison between TS-2000 / RTL /
FunCube Pro+ can be seen here:
https://youtu.be/3OxyO5ylwfs
73
ED ? PY2RN
From: Patrick STODDARD (WD9EWK/VA7EWK) <amsat-bb@xxxxxx.xxx>
To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Sent: Thursday, June 16, 2016 5:22 PM
Subject: Re: [amsat-bb] RTL-SDR downlink
Hi, (name or call?)!
The inexpensive RTL-SDR dongles are a great way to get started with
SDR receivers. For amateur satellite work, other than the ISS and maybe
AO-85, they have a couple of significant drawbacks...
1. These dongles were designed to be TV receivers, working with
signals much stronger than we have from our satellites or even the
ISS ham station.
2. These dongles lack front-end filtering. This means that there could
be a strong signal near you that swamps the receiver that wipes out
what you're trying to hear. If you are trying to work satellites
full-duplex, it is possible that your transmitter will shut down
the dongle until you end your transmission. This was a problem I
experienced early on when I tried using one of these dongles as
my downlink receiver, and quickly moved on to something else.
Unfortunately there isn't anything in the middle ground between these
dongles and devices like the SDRplay (sold by HRO in the US for $149)
or the FUNcube Dongle Pro+ (sold by its UK manufacturer for around
$200 depending on exchange rates, which includes FedEx next-day
shipping from England to most addresses in the continental USA). Both
of these devices do well as the downlink receiver for working
satellites. Both come with front-end filtering that the RTL-SDR
dongles lack, and still have sensitive receivers. The SDRplay
has a low-noise amplifier that is engaged when receiving at VHF or
higher, but you can reduce the amount of gain from the built-in LNA.
For my work, I keep that gain reduction value set to 0, so I have
maximum gain to hear the downlinks.
Good luck, and 73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
Twitter: @xxxxxx
On Thu, Jun 16, 2016 at 2:30 PM, bruisedreed@xxxx.xxx <bruisedreed@xxxx.xxx>
wrote:
> Hello all!? Been lurking a while here and just wanted to say hi and thanks
> to everyone.? Just started working the birds. VERY limited success so far
> on the linear transponders. Limited budget leads me to either have to run
> in half duplex (obviously not preferred) or come up with another low cost
> receiving option. I bought an RTL-SDR to see if it could be any help. I
> have to say I really like this little receiver. It’s a little buggy
> figuring things out but it receives really pretty well…UNTIL I try
> to receive CW and SSB on the transponders. I have no problem receiving FM
> repeaters and simplex and have monitored a few SO50 passes with it no
> problem, but for some reason I’m not hearing the same signals I can
> hear on the receiver of my FT100 with the EXACT same antenna. I A/B them
> and have nothing on the SDR. Is anyone using one of these? I am probably
> missing something simple. When I started receiving HF I couldn’t make
> it work until I figured out I had
>? to change the sampeling in the setup to direct from
> quadrature…only learned that through a forum and I assume something
> like that will make the thing come to life. Lack of documentation on some
> of these things is kind of a pain. Thanks in advance for any help you can
> offer and my apologies to anyone I have frustrated working half duplex! I
> will figure out what I’m doing!
> ____________________________________________________________
>
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. 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
------------------------------
Message: 4
Date: Thu, 16 Jun 2016 17:04:07 -0700
From: Cass Hussmann <cass.hussmann@xxxxx.xxx>
To: M5AKA <m5aka@xxxxx.xx.xx>
Cc: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] "Only Half of the CubeSats Deployed into Space
Work"
Message-ID:
<CAHno9EevL_S4v7U7dj=daZRP7GohcFzTi9AjjyHotqQw8FpR-w@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Cubesat plots setup by M. Swartwout has some good information regarding the
historical success rate of cube satellites. the number was likely refering
to cube satellites in general not OSCARs specifically.
https://sites.google.com/a/slu.edu/swartwout/home/cubesat-database
<https://sites.google.com/a/slu.edu/swartwout/home/cubesat-database>
On Thu, Jun 16, 2016 at 11:54 AM, M5AKA via AMSAT-BB <amsat-bb@xxxxx.xxx>
wrote:
> ARRL story quotes NASA engineer Joe Pellegrino as saying "Only Half of the
> CubeSats Deployed into Space Work" - is the failure rate really that high?
>
http://www.arrl.org/news/view/stmsat-1-youngsters-told-only-half-of-the-cubesa
ts-deployed-into-space-work
>
> I've certainly noticed that a number of ISS deployed CubeSats using
> amateur frequencies which were subject to delays in the initial launch and
> then more delays before actual deployment have failed but it certainly
> didn't seem to be as high as 50%
>
> But most ISS CubeSat deployments are not on amateur frequencies e.g. over
> 100 Planet Labs Dove CubeSats have been deployed. Was the NASA engineer
> saying that half of Planet Labs satellites failed to work?
>
> 73 Trevor M5AKA
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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
>
--
Cass Hussmann, BENG
*Chief Engineer*
*UVic ECOSat Team*
ecosat.ca
Tel: 778-410-2414 (ext 1001)
Personal Tel: 778-679-6695
------------------------------
Message: 5
Date: Thu, 16 Jun 2016 21:55:38 -0400
From: "Daniel Schultz" <n8fgv@xxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Only Half of the CubeSats Deployed into Space
Work
Message-ID: <695uFqB3M9616S05.1466128538@xxxxx.xxx.xxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
I just attended a talk on Tuesday by professor Michael Swartwout of Saint
Louis University. He maintains a database of all known Cubesats at:
https://sites.google.com/a/slu.edu/swartwout/home/cubesat-database
According to his most recent data, about 25% of recent Cubesats are dead on
arrival in orbit, and another 12% fail early in the mission. 50% of Cubesats
are classified as fully or partially successful. He attributes this mostly to
inexperienced organizations building their first satellite with little
understanding of the space environment and little or no environmental testing
before launch. A certain amount of first timer "we know everything" arrogance
also factors into that statistic. Satellites in space definitely don't work
the same as satellites on the workbench. Many of these "one and done"
organizations quit building satellites after their first failure, those
organizations that launch multiple Cubesats have much better success rates.
Experience does count for something.
Even for tiny little Cubesats, there is a set of "best practices" that you
need to pay attention to when building your satellite. If it is your
organization's first satellite, you need to be mindful of what you don't know
and try to learn from the experience of others.
Slides from an earlier presentation by Professor Swartwout are at:
http://nepp.nasa.gov/workshops/eeesmallmissions/talks/11%20-%20THU/1300%20-%20
swartwout%20eee%20201409%20v2.pdf
I expect that this year's presentation will be posted online in a few days.
Dan Schultz N8FGV
------------Original Message------------
Date: Thu, 16 Jun 2016 18:54:05 +0000 (UTC)
From: M5AKA <m5aka@xxxxx.xx.xx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] "Only Half of the CubeSats Deployed into Space
Work"
Message-ID:
<528856269.7643560.1466103245274.JavaMail.yahoo@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
ARRL story quotes NASA engineer Joe Pellegrino as saying "Only Half of the
CubeSats Deployed into Space Work" - is the failure rate really that
high?http://www.arrl.org/news/view/stmsat-1-youngsters-told-only-half-of-the-c
ub
esats-deployed-into-space-work
I've certainly noticed that a number of ISS deployed CubeSats using amateur
frequencies which were subject to delays in the initial launch and then more
delays before actual deployment have failed but it certainly didn't seem to
be
as high as 50%
But most ISS CubeSat deployments are not on amateur frequencies e.g. over 100
Planet Labs Dove CubeSats have been deployed. Was the NASA engineer saying
that
half of Planet Labs satellites failed to work?
73 Trevor M5AKA
------------------------------
Message: 6
Date: Thu, 16 Jun 2016 21:08:34 -0500
From: Peter Laws <plaws0@xxxxx.xxx>
To: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Only Half of the CubeSats Deployed into Space
Work
Message-ID:
<CANVAiQ_Ed1nu1GFpo2=WZxCMtpeqNbpY-E6rE4ir08-+ByMyGQ@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
On Thu, Jun 16, 2016 at 8:55 PM, Daniel Schultz <n8fgv@xxx.xxx> wrote:
> . 50% of Cubesats
> are classified as fully or partially successful.
Given that so many are built by people who are *not* *actually* rocket
scientists, 50% success seems pretty good. I mean, it's not like
there are astronauts on them -- failure can be an option -- but it
would be prudent for organizations to keep that 50% thing in mind.
Hopefully lessens the disappointment.
--
Peter Laws | N5UWY | plaws plaws net | Travel by Train!
------------------------------
Message: 7
Date: Thu, 16 Jun 2016 23:18:34 -0400
From: Arthur Feller <afeller@xxxx.xxx>
To: Peter Laws <plaws0@xxxxx.xxx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Only Half of the CubeSats Deployed into Space
Work
Message-ID: <57823D3E-4614-408B-AEE5-7A9AD36CBD7F@xxxx.xxx>
Content-Type: text/plain; charset=utf-8
Oh, please. Expending all the time, effort, and money to do a project, at
least try to do it right instead of launching a rock (aka space litter).
Someone else working harder can use the opportunity wasted by poor quality
work.
Failure is an option to be avoided insofar as possible. Just ask AMSAT
developers and builders.
73, art?..
W4ART Arlington VA
> On 16-Jun-2016, at 10:08 PM, Peter Laws <plaws0@xxxxx.xxx> wrote:
>
> On Thu, Jun 16, 2016 at 8:55 PM, Daniel Schultz <n8fgv@xxx.xxx> wrote:
>> . 50% of Cubesats
>> are classified as fully or partially successful.
>
>
> Given that so many are built by people who are *not* *actually* rocket
> scientists, 50% success seems pretty good. I mean, it's not like
> there are astronauts on them -- failure can be an option -- but it
> would be prudent for organizations to keep that 50% thing in mind.
> Hopefully lessens the disappointment.
>
>
> --
> Peter Laws | N5UWY | plaws plaws net | Travel by Train!
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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
Everyone, in some small sacred sanctuary of the self, is nuts.
-Leo Rosten, author (1908-1997)
http://afeller.us <http://afeller.us/>
------------------------------
Message: 8
Date: Fri, 17 Jun 2016 04:14:09 +0000
From: B J <va6bmj@xxxxx.xxx>
To: Arthur Feller <afeller@xxxx.xxx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Only Half of the CubeSats Deployed into Space
Work
Message-ID:
<CAP7QzkPHxQ+1t6W5njseX9W8zmyS4z3gvGjq42BFwBPCmtqKhw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
On 6/17/16, Arthur Feller <afeller@xxxx.xxx> wrote:
> Oh, please. Expending all the time, effort, and money to do a project, at
> least try to do it right instead of launching a rock (aka space litter).
> Someone else working harder can use the opportunity wasted by poor quality
> work.
>
> Failure is an option to be avoided insofar as possible. Just ask AMSAT
> developers and builders.
<snip>
Two years ago, I offered to help some engineering students with their
cubesat project. I figured that my experience in satellite operations
as a ham plus having worked in the business for a while as an
engineer, they would welcome what I had to say.
All I had was 3 meetings and I never heard from them again. I guess
they had all the answers and didn't need the advice of a silverback
like me.
I have no idea of they finished it or, if they did, if it even works.
I don't think it'll be going into space any time soon, though, as the
launch firm that I think they wanted to use may not even have a
rocket. I told them that as well, but I guess they knew everything
better.
73s
Bernhard VA6BMJ @ DO33FL
------------------------------
Message: 9
Date: Fri, 17 Jun 2016 09:02:47 +0200
From: Rico van Genugten <rico.van.genugten@xxxxx.xxx>
To: Eduardo PY2RN <py2rn@xxxx.xxx>
Cc: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] RTL-SDR downlink
Message-ID:
<CAJdc4v757xA2OzgnKjGoVxViH8P1z4cAh7U4b+ugFxvqQPSD1A@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Hi all,
I am using RTL-SDR's for downlink reception for quite some time now. I've
got one from the rtl-sdr blog in aluminum casing with TCXO. I can hear the
downlinks of pretty much all the LEO's (except SO-50) fine with it using
indoor antennas. In my experience it is easier copying the downlinks of
linear birds, as the required SNR for a copyable signal in SSB is lower.
I can also successfully decode ISS APRS packets using a vertical, RTL-SDR,
GQRX and direwolf, so that makes for a very cheap ISS APRS receive setup.
Note: the gnuradio FM demodulator in GQRX works way better than rtl_fm,
using the latter I cannot decode any packets. GQRX is pretty CPU-hungry
though, so a Raspberry Pi solution would be tricky. (/offtopic)
As others said, the RTL-SDR has no front-end filtering and therefore
terrible desense, furthermore it has a pretty low dynamic range, so full
duplex operation is not possible. Nonetheless I've made a couple of QSO's
via AO-85 using the RTL-SDR on the receiving end, just ignoring the audio
when TXing.
I have an AirSpy Mini on order now, I'm curious how it will perform with
nearby TXing. AFAIK it doesn't have any front-end filtering like the
SDRPlay or FunCube dongles have, but the dynamic range is way bigger than
the RTL-SDR's, so hopefully it will still perform a lot better. Otherwise
I'll have to build some filters.
Regards,
Rico PA3RVG
On Fri, Jun 17, 2016 at 1:08 AM, Eduardo PY2RN <py2rn@xxxx.xxx> wrote:
> The cheap RTL dongles are as much sensible (or more) than the others more
> expensive.Lack of filtering is the big issue although there are some
> practical and easy workarounds to improve it.For ham satellites downlink
> frequency stability should not be an big issue, there are some models
> already been sold with 0.5PPM TCXO option which are still cheap.It is a
> great opportunity to operate full-duplex on amateur satellites with very
> low investment and improving operational capabilities.
> EME (Moon bounce) audible signal RX comparison between TS-2000 / RTL /
> FunCube Pro+ can be seen here:
> https://youtu.be/3OxyO5ylwfs
>
> 73
> ED PY2RN
>
>
> From: Patrick STODDARD (WD9EWK/VA7EWK) <amsat-bb@xxxxxx.xxx>
> To: "amsat-bb@xxxxx.xxxx <amsat-bb@xxxxx.xxx>
> Sent: Thursday, June 16, 2016 5:22 PM
> Subject: Re: [amsat-bb] RTL-SDR downlink
>
> Hi, (name or call?)!
>
> The inexpensive RTL-SDR dongles are a great way to get started with
> SDR receivers. For amateur satellite work, other than the ISS and maybe
> AO-85, they have a couple of significant drawbacks...
>
> 1. These dongles were designed to be TV receivers, working with
> signals much stronger than we have from our satellites or even the
> ISS ham station.
>
> 2. These dongles lack front-end filtering. This means that there could
> be a strong signal near you that swamps the receiver that wipes out
> what you're trying to hear. If you are trying to work satellites
> full-duplex, it is possible that your transmitter will shut down
> the dongle until you end your transmission. This was a problem I
> experienced early on when I tried using one of these dongles as
> my downlink receiver, and quickly moved on to something else.
>
> Unfortunately there isn't anything in the middle ground between these
> dongles and devices like the SDRplay (sold by HRO in the US for $149)
> or the FUNcube Dongle Pro+ (sold by its UK manufacturer for around
> $200 depending on exchange rates, which includes FedEx next-day
> shipping from England to most addresses in the continental USA). Both
> of these devices do well as the downlink receiver for working
> satellites. Both come with front-end filtering that the RTL-SDR
> dongles lack, and still have sensitive receivers. The SDRplay
> has a low-noise amplifier that is engaged when receiving at VHF or
> higher, but you can reduce the amount of gain from the built-in LNA.
> For my work, I keep that gain reduction value set to 0, so I have
> maximum gain to hear the downlinks.
>
> Good luck, and 73!
>
>
>
>
>
> Patrick WD9EWK/VA7EWK
> http://www.wd9ewk.net/
> Twitter: @xxxxxx
>
>
>
>
>
> On Thu, Jun 16, 2016 at 2:30 PM, bruisedreed@xxxx.xxx <
> bruisedreed@xxxx.xxx>
> wrote:
>
> > Hello all! Been lurking a while here and just wanted to say hi and
> thanks
> > to everyone. Just started working the birds. VERY limited success so far
> > on the linear transponders. Limited budget leads me to either have to run
> > in half duplex (obviously not preferred) or come up with another low cost
> > receiving option. I bought an RTL-SDR to see if it could be any help. I
> > have to say I really like this little receiver. It’s a little buggy
> > figuring things out but it receives really pretty well…UNTIL I try
> > to receive CW and SSB on the transponders. I have no problem receiving FM
> > repeaters and simplex and have monitored a few SO50 passes with it no
> > problem, but for some reason I’m not hearing the same signals I can
> > hear on the receiver of my FT100 with the EXACT same antenna. I A/B them
> > and have nothing on the SDR. Is anyone using one of these? I am probably
> > missing something simple. When I started receiving HF I couldn’t
> make
> > it work until I figured out I had
> > to change the sampeling in the setup to direct from
> > quadrature…only learned that through a forum and I assume
> something
> > like that will make the thing come to life. Lack of documentation on some
> > of these things is kind of a pain. Thanks in advance for any help you can
> > offer and my apologies to anyone I have frustrated working half duplex! I
> > will figure out what I’m doing!
> > ____________________________________________________________
> >
> _______________________________________________
> Sent via AMSAT-BB@xxxxx.xxx. 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@xxxxx.xxx. 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
>
------------------------------
Message: 10
Date: Fri, 17 Jun 2016 07:44:42 +0000 (UTC)
From: M5AKA <m5aka@xxxxx.xx.xx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: Re: [amsat-bb] Only Half of the CubeSats Deployed into Space
Work
Message-ID:
<1026481493.8038459.1466149482661.JavaMail.yahoo@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=UTF-8
Thanks,
The figures from the chart show 14.8% of CubeSats fail to work on Deployment
and 8% cease working shortly after Deployment.
A long way from the claimed 50% of those CubeSats actually Deployed in space
don't work.
73 Trevor M5AKA
------------------------------
Subject: Digest Footer
_______________________________________________
Sent via amsat-bb@xxxxx.xxx.
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!
http://www.amsat.org/mailman/listinfo/amsat-bb
------------------------------
End of AMSAT-BB Digest, Vol 11, Issue 194
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