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! ____________________________________________________________ Los Angeles Post This Father and Son Took the Same Photo 28 Years in a Row, Last One is ... http://thirdpartyoffers.juno.com/TGL3131/5762b832d809e38323b6ast03vuc
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: @WD9EWK
On Thu, Jun 16, 2016 at 2:30 PM, [email protected] [email protected] 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! ____________________________________________________________
On Thu, Jun 16, 2016 at 3:22 PM, Patrick STODDARD (WD9EWK/VA7EWK) [email protected] wrote:
Unfortunately there isn't anything in the middle ground between these dongles and devices like the
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.
I did some experimentation with the $20 dongle vs the FunCube dongle for receiving weather satellites.
If you live in an RF dense area, like here in Southern California, they BOTH benefit from having some front-end filtering added.
Other wise you have to turn the RF gain down quite a bit on both of them to prevent 'break through' from strong signals that can be may MHz away from your band of interest.
In my case, I used an SSB Electronik 2 Meter preamp with an old M2 2 Meter Eggbeater antenna. I could get reasonable copy above 10*~15* elevation with just the dongle and antenna, but suffered from strong signal break through. If I turned the RF gain down to where the interfering signals no longer broke through, it cut my reception down to maybe 25*~30* elevation.
With the SSB preamp and it's built-in helical filter, even operating at 137 MHz, the difference was staggering, and I could get good copy down to 5* or so.
The only other SDR I played with for a while was the HackRF, which I found to be unsuitable for what I was looking for. Despite the hype behind it, it's still an 8-bit unit with limited dynamic range.
YMMV!
73, Jim KQ6EA
On 06/16/2016 08:33 PM, Peter Laws wrote:
On Thu, Jun 16, 2016 at 3:22 PM, Patrick STODDARD (WD9EWK/VA7EWK) [email protected] wrote:
Unfortunately there isn't anything in the middle ground between these dongles and devices like the
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.
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: @WD9EWK
On Thu, Jun 16, 2016 at 8:33 PM, Peter Laws [email protected] 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.
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...
- 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.
- 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: @WD9EWK
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) [email protected] To: "[email protected]" [email protected] 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: @WD9EWK
On Thu, Jun 16, 2016 at 2:30 PM, [email protected] [email protected] 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 [email protected]. 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
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 [email protected] 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) <[email protected]>To: "[email protected]" [email protected] 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...
- 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.
- 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: @WD9EWK
On Thu, Jun 16, 2016 at 2:30 PM, [email protected] < [email protected]> 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 [email protected]. 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 [email protected]. 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
Hello, Ed!
Thanks for your reply! If I had my satellite station in a proper ham shack, where the radios are inside and antennas are outside (or the antennas are not within a few feet or a couple of meters of the radios), it is possible that the house or building may be enough to keep the transmitter from affecting the RTL-SDR dongles. I don't have that option for working satellites, even when I am at home. My antenna is always within a few feet or a couple of meters of my radios, both transmit and receive. Putting the dongle in a case with some shielding, and maybe adding some filters in front of the dongle, could make that work in my situation. Between the time and money needed to do that, I think I'm doing fine when I use a FUNcube Dongle Pro+ or SDRplay. In fact, whenever I move to a place where I can install a proper satellite station in the house, with antennas outside and the radios inside, I know my existing SDR receivers (FUNcube Dongle Pro+ and SDRplay) should work fine in that environment as they have when I've worked portable.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
On Thu, Jun 16, 2016 at 11:08 PM, Eduardo PY2RN [email protected] 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
Hi Patrick. Agreed, it will depend on the environment conditions for each one/station. Usually devices connected to a computer are very subject to suffer with RFI /EMI all the ways, USB cables makes great antennas, unfortunately. So toroids and shielding are a must, but may be not enough sometimes.
Regarding metal cases for these dongles (not only RTL, but FCD and others with plastic cases) 3M and similar have a thin copper tape which is auto-adhesive (and yes, the adhesive side is conductive as well!) I am using to mitigate RFI/EMI on these devices, and other plastic boxes I have here. 73 Ed PY2RN
From: Patrick STODDARD (WD9EWK/VA7EWK) [email protected] To: "[email protected]" [email protected] Sent: Friday, June 17, 2016 1:16 PM Subject: Re: [amsat-bb] RTL-SDR downlink
Hello, Ed!
Thanks for your reply! If I had my satellite station in a proper ham shack, where the radios are inside and antennas are outside (or the antennas are not within a few feet or a couple of meters of the radios), it is possible that the house or building may be enough to keep the transmitter from affecting the RTL-SDR dongles. I don't have that option for working satellites, even when I am at home. My antenna is always within a few feet or a couple of meters of my radios, both transmit and receive. Putting the dongle in a case with some shielding, and maybe adding some filters in front of the dongle, could make that work in my situation. Between the time and money needed to do that, I think I'm doing fine when I use a FUNcube Dongle Pro+ or SDRplay. In fact, whenever I move to a place where I can install a proper satellite station in the house, with antennas outside and the radios inside, I know my existing SDR receivers (FUNcube Dongle Pro+ and SDRplay) should work fine in that environment as they have when I've worked portable.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
On Thu, Jun 16, 2016 at 11:08 PM, Eduardo PY2RN [email protected] 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
_______________________________________________ Sent via [email protected]. 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
Hi Patrick. Agreed, it will depend on the environment conditions for each one/station. Usually devices connected to a computer are very subject to suffer with RFI /EMI all the ways, USB cables makes great antennas, unfortunately. So toroids and shielding are a must, but may be not enough sometimes.
Regarding metal cases for these dongles (not only RTL, but FCD and others with plastic cases) 3M and similar have a thin copper tape which is auto-adhesive (and yes, the adhesive side is conductive as well!) I am using to mitigate RFI/EMI on these devices, and other plastic boxes I have here. 73 Ed PY2RN
From: Patrick STODDARD (WD9EWK/VA7EWK) [email protected] To: "[email protected]" [email protected] Sent: Friday, June 17, 2016 1:16 PM Subject: Re: [amsat-bb] RTL-SDR downlink
Hello, Ed!
Thanks for your reply! If I had my satellite station in a proper ham shack, where the radios are inside and antennas are outside (or the antennas are not within a few feet or a couple of meters of the radios), it is possible that the house or building may be enough to keep the transmitter from affecting the RTL-SDR dongles. I don't have that option for working satellites, even when I am at home. My antenna is always within a few feet or a couple of meters of my radios, both transmit and receive. Putting the dongle in a case with some shielding, and maybe adding some filters in front of the dongle, could make that work in my situation. Between the time and money needed to do that, I think I'm doing fine when I use a FUNcube Dongle Pro+ or SDRplay. In fact, whenever I move to a place where I can install a proper satellite station in the house, with antennas outside and the radios inside, I know my existing SDR receivers (FUNcube Dongle Pro+ and SDRplay) should work fine in that environment as they have when I've worked portable.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
On Thu, Jun 16, 2016 at 11:08 PM, Eduardo PY2RN [email protected] 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
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Outside of my back window is Poor Mountain. I can see two television towers, two FM radio stations, three paging transmitters, .....
The RTL-SDR is absolutely useless, period, even on a paper clip antenna without filtering.
Bob N4HY
On Thu, Jun 16, 2016 at 4:22 PM, Patrick STODDARD (WD9EWK/VA7EWK) < [email protected]> 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...
- 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.
- 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: @WD9EWK
On Thu, Jun 16, 2016 at 2:30 PM, [email protected] < [email protected]> 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! ____________________________________________________________
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participants (9)
-
bruisedreed＠juno.com -
Eduardo Erlemann -
Eduardo PY2RN -
Jim Barbre -
Jim Jerzycke -
Patrick STODDARD (WD9EWK/VA7EWK) -
Peter Laws -
Rico van Genugten -
Robert McGwier