Povern, the go to guy on the SDR stuff is Patrick Stoddard, WD9EWK. Awile back, Patrick posted the following info on this board. I'm sure he won't mind me reposting:

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 Since these were originally made as television receivers, they were designed for use with stronger signals than what we typically see from our satellites.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.

73 and GL

Ted K7TRK

A little off topic, but the RTL-SDR.com v3 dongle does support HF without up converting, and is inexpensive. They are a good way to play with SDR and not spend a lot of money to do it.

As mentioned, it will shut down due to near by transmissions. I attempted it on a linear bird one time with it hooked up to my Android phone and SDR Touch app.

73, Don KB2YSI

On Feb 12, 2018 20:43, "Jason Rearick" [email protected] wrote:

Paul, I have been using an SDRPlay RSP1 for my downlink on linear sats for a little while now. I use a FT-817 for the uplink, and drive them both with SatPC32. It works well and you can find a video on YouTube that shows the setup very well.

Jason N3YUG

-----Original Message----- From: Povern via AMSAT-BB Sent: Monday, February 12, 2018 5:10 PM To: [email protected] Subject: [amsat-bb] SDR for fm sats

Anyone using sdr for linear sats? Very new to these and have zero experience with sdr. Looking for any input and hints for using these for the ssb birds.

KE0PBR

Paul Overn

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