SDRPlay for satellite operation

[EA4SG]

Hello SDR community :

I am EA4SG David.

I would like to use SDRPlay for satellite operation.

My setup will be the next:

I will use Icom IC910H with 50W for TX
I will use SDR for RX

See images of my antennas setup on the bottom of the message. Distance from UHF and VHF antennas is aroun 350mm

Coax lines are separated. One cable for each antenna.

Depending on the satellite the IC910H will be transmitting in VHF and SDRPlay receiving on UHF and viceversa.

There is a big "frequency gap" between VHF and UHF and SDRPlay will never been receiving on the same band as the radio will transmit, but as the antennas are close one to each the other... Is there any risk for SDRPlay to be damaged?

Any comment from SDRPlay support team or from any satellite operator ussing similar setup will be really appreciated.

Best 73s de David EA4SG

[wd9ewk]

I would like to use SDRPlay for satellite operation.

<snip>

Depending on the satellite the IC910H will be transmitting in VHF and SDRPlay receiving on UHF and viceversa.

There is a big "frequency gap" between VHF and UHF and SDRPlay will never been receiving on the same band as the radio will transmit, but as the antennas are close one to each the other... Is there any risk for SDRPlay to be damaged?

I have been using an SDRplay for working amateur satellites over the past few months. It is a great receiver for that purpose. I normally use two radios for my operating, something to transmit and the SDRplay as my receiver, connected through a diplexer to an Elk Antennas handheld 2m/70cm log periodic antenna. The diplexer is necessary, as the log periodic has a single coax feedpoint, and I have two radios. The diplexer also acts as a filter with at least 60dB isolation between the two band ports, in addition to the front-end filtering in the SDRplay.

To answer your question, I have operated at up to 50W transmit power on one band (either 2m or 70cm), and have no problems receiving on the opposite band with my SDRplay. Normally I use 5W for SSB operating with an FT-817ND as my transmitter, but for FM I often use a 2m/70cm FM mobile like an Icom IC-2820H or IC-2730A, which has 3 transmit power levels (5/15/50W). The front-end filtering in the SDRplay (also present in the FUNcube Dongle Pro+) is a big advantage over the inexpensive "RTL-SDR" dongles we can buy from many places.

Here are a couple of photos of how I have used my SDRplay for working satellites from portable stations. First, using it with an 8-inch Windows 10 tablet and an Icom IC-2820H 2m/70cm FM mobile radio as my transmitter. This was for working the AO-85 satellite in mid-October, while I was on a trip. I stopped at a freeway/motorway rest area north of Indianapolis, in Indiana, when I used this setup:

IC-2820H, 8-inch Windows 10 tablet with HDSDR, and SDRplay for working AO-85 from a motorway rest area north of Indianapolis, Indiana (USA) on 15 October 2015

IMG_20151014_185314.jpg (167.97 KiB) Viewed 25203 times

A few days later on the same trip, I was near the Canada/USA border in Michigan, northeast of Detroit at Port Huron (across from Sarnia in Ontario), when I used an FT-817ND as my transmit radio with the SDRplay to work AO-73:

FT-817ND, 8-inch Windows 10 tablet with HDSDR, and SDRplay for working AO-73 from Port Huron, Michigan (USA) on 20 October 2015

IMG_20151019_213806.jpg (151.54 KiB) Viewed 25203 times

In both instances, I connected the radio I used and my SDRplay to a diplexer which is sitting behind the tablet in each photo, and then to my Elk log periodic which is not visible in either photo.

I like using the SDRplay to work AO-85, since I can write an RF recording and then play it back into AMSAT's FoxTelem software to upload telemetry from the satellite to AMSAT's server. For AO-73 and other satellites like AO-7 and FO-29 with linear transponders for SSB/CW operation, I can capture the entire transponder in the RF recording written by HDSDR. If I used a more powerful computer, I could use a virtual audio cable from HDSDR and feed the received signals in real time to FoxTelem or the FUNcube Dashboard for AO-73, and upload telemetry in real time to those servers (provided I have Internet access from wherever I am operating).

I think you will be happy with the SDRplay for satellite work. I tried SDR# when I bought my SDRplay last summer, but did not like its user interface. HDSDR has a lot of options, but it seems to be easier to run on my inexpensive Windows tablets. I have used SDR-Console on a larger laptop, but don't use that on the tablets due to its appetite for memory and CPU that the tablets lack. Otherwise, SDR-Console is a good program like HDSDR.

If you want to see more of what I have been doing with my SDRplay, you can visit my public Dropbox space at http://dropbox.wd9ewk.net/ and browse through the folders with dates and satellite names on them. I have placed RF recordings I made of those passes (large WAV files), audio recordings (MP3s), and photos of my setups and of my AmsatDroid Free tracking app showing the passes I worked. I also wrote an article about using SDR and the inexpensive Windows tablets (at the time, Windows 8.1, but it can also apply to the newer Windows 10 tablets) for satellite operating. It was not specific to the SDRplay, but it is in the Articles folder in my Dropbox space (originally written for the AMSAT Journal last year, then reprinted in AMSAT-UK's OSCAR News a few months later).

Buena suerte, & 73!!

[EA4SG]

connected through a diplexer to an Elk Antennas handheld 2m/70cm log periodic antenna. The diplexer is necessary, as the log periodic has a single coax feedpoint, and I have two radios. The diplexer also acts as a filter with at least 60dB isolation between the two band ports, in addition to the front-end filtering in the SDRplay.

To answer your question, I have operated at up to 50W transmit power on one band (either 2m or 70cm), and have no problems receiving on the opposite band with my SDRplay. Normally I use 5W for SSB operating with an FT-817ND as my transmitter, but for FM I often use a 2m/70cm FM mobile like an Icom IC-2820H or IC-2730A, which has 3 transmit power levels (5/15/50W).

In both instances, I connected the radio I used and my SDRplay to a diplexer which is sitting behind the tablet in each photo, and then to my Elk log periodic which is not visible in either photo.

I like using the SDRplay to work AO-85, since I can write an RF recording and then play it back into AMSAT's FoxTelem software to upload telemetry from the satellite to AMSAT's server. For AO-73 and other satellites like AO-7 and FO-29 with linear transponders for SSB/CW operation, I can capture the entire transponder in the RF recording written by HDSDR. If I used a more powerful computer, I could use a virtual audio cable from HDSDR and feed the received signals in real time to FoxTelem or the FUNcube Dashboard for AO-73, and upload telemetry in real time to those servers (provided I have Internet access from wherever I am operating).

I think you will be happy with the SDRplay for satellite work. I tried SDR# when I bought my SDRplay last summer, but did not like its user interface. HDSDR has a lot of options, but it seems to be easier to run on my inexpensive Windows tablets. I have used SDR-Console on a larger laptop, but don't use that on the tablets due to its appetite for memory and CPU that the tablets lack. Otherwise, SDR-Console is a good program like HDSDR.

Buena suerte, & 73!!

Hello Patrick.

Thanks for your interesting answer. You have a really nice, optimal, practical and portable setup. Congratulations. I have taken some ideas after see your mobile station.

But my QTH setup is different. I dont operate with and I dont have the intention of ussing diplexer. What I have instaled and I can not modify is two antennas (1 for VHF and 2 for UHF), very near one to the other, each antenna with its own coax cable. TX will be done with the radio and one of the antennas and RX will be done with SDR and the second independent antenna.

I have been working with SDRPlay and I have no doubt about its RX capacity. I have been able to decode without problems not only the AO-85 DUV telemetry, also hardest tasks as 9K6 FSK telemetry from several UHF cubesats, or even the Firebird2-FU3 and FU4 sats 19K6 FSK telemetry, thanks not, only to the good sensibility of SDRPlay, also thanks to the chance or play and replay IQ recordings as you mentioned. I agree with you that this is something very useful for experimentation.

Anyway I ASK AGAIN MY QUESTION about my setup and trying to know if there is any risk for the SDRPlay during the operation I am planning... There is a big "frequency gap" between VHF and UHF, coax are independent for TX and RX and SDRPlay will never been receiving on the same band as the radio will transmit, but as the antennas are close one to each the other... Is there any risk for SDRPlay to be damaged having a TX antenna at that distance?

Can SDR support team analize and give me his comments?

Thanks in advance.

Best 73s
David EA4SG

[wd9ewk]

I dont operate with and I dont have the intention of ussing diplexer. What I have instaled and I can not modify is two antennas (1 for VHF and 2 for UHF), very near one to the other, each antenna with its own coax cable. TX will be done with the radio and one of the antennas and RX will be done with SDR and the second independent antenna.

I have also operated with separate antennas for my satellite station - transmitting from a radio with the Elk log periodic, receiving with SDRplay connected to a Winkler VHF turnstile (crossed dipole) for satellites with VHF downlinks like AO-73 and AO-85. I bought that crossed dipole from AMSAT-UK's web site. In this setup, I did not employ a diplexer for either antenna, just coax between radios and antennas.

Here is an example of how I did this, for an AO-85 pass in late November 2015:

WD9EWK's station for working AO-85 on 22 November 2015. 70cm uplink: Wouxun KG-UV9D to Elk Antennas 2m/70cm log periodic. 2m downlink: SDRplay with 8-inch Windows 10 tablet running HDSDR to Winkler (AMSAT-UK) VHF crossed dipole.

IMG_20151122_163045.jpg (148.06 KiB) Viewed 25124 times

This was for a pass that started to my north, ending to my east, and at times I was pointing my Elk log periodic at my crossed dipole. I did not see or hear anything that indicated my 70cm uplink was coming in on the SDRplay, which was listening around 145.980 MHz for the 2m downlink.

I have also done this for working AO-73 and the recently-launched XW-2 satellites with 70cm/2m SSB/CW transponders, where I used a Yaesu FT-817ND for my 70cm uplink transmitter connected to the Elk. The 2m downlink was handled by the SDRplay and crossed dipole. Just like when I have worked FM satellites with this two-antenna configuration, I saw no problems with the SDRplay in this configuration.

I have been working with SDRPlay and I have no doubt about its RX capacity. I have been able to decode without problems not only the AO-85 DUV telemetry, also hardest tasks as 9K6 FSK telemetry from several UHF cubesats, or even the Firebird2-FU3 and FU4 sats 19K6 FSK telemetry, thanks not, only to the good sensibility of SDRPlay, also thanks to the chance or play and replay IQ recordings as you mentioned. I agree with you that this is something very useful for experimentation.

I think the SDRplay has a little more sensitivity than my FUNcube Dongle Pro+, a reason why I use it more for my satellite work. The ability to make IQ recordings is a powerful tool.

Anyway I ASK AGAIN MY QUESTION about my setup and trying to know if there is any risk for the SDRPlay during the operation I am planning... There is a big "frequency gap" between VHF and UHF, coax are independent for TX and RX and SDRPlay will never been receiving on the same band as the radio will transmit, but as the antennas are close one to each the other... Is there any risk for SDRPlay to be damaged having a TX antenna at that distance?

I'll let SDRplay answer with more specifics regarding the risks, but I find that the bandpass filtering in the SDRplay is more than capable of letting you work satellites using a two-antenna station like you have, without your transmitter frying the SDRplay. I'm using the same SDRplay I bought last summer, have used it in different station configurations at home and on the road, and it's still working well. I have bought a few more SDRplay RSPs, one for use at home, and a couple of others that will eventually find new homes. I am careful to ensure I don't transmit on the same frequency or band my SDRplay is listening on, but I wouldn't worry if I had a 50W transceiver connected to one antenna and the SDRplay connected to another antenna for satellite work.

73!

[jon]

Thanks Patrick and Hello Dave,

It’s a close call and I’m wary of just saying it will be fine because it’s impossible to guess the real world isolation your set-up is creating.

Here is my thinking (not as an RF antenna expert btw):

We specify a maximum of 0dBM signal level to be presented to the RSP. This is the continuous figure. In practice, a short burst of 10dBM will not cause a problem. However, you should not exceed this even if the RSP is receiving in a completely different (RSP) band with added filter attenuation downstream.

So what we need to ensure is that there is 40dB isolation between your 50W (50dBm) TX and the RSP RX antenna

Your driven elements are not on top of each other vertically - you have approximately 1 metre of horizontal separation and the beam forming gain of each antenna is all helping reduce the coupling.

People try to tabulate isolation in graphs like the ones shown here:

http://www.repeater-builder.com/antenna/separation.html

You will also get another 10dB+ isolation (again, my guess) due to the resonant lengths being a 3rd harmonic relationship rather than the same or double the frequency.

My gut feel is you are getting somewhere between 35dB and 50dB isolation, but the honest answer is I don’t know and the only way to be sure is to make a measurement – e.g. using something like the MJF power meter: http://www.mfjenterprises.com/Product.p ... id=MFJ-801

Looking around the internet I have come across this useful article http://www.jpole-antenna.com/2013/07/28 ... -antennas/ which is encouraging.

Sorry I cannot be 100% definitive - we’d love to hear of any others who have similar set-ups and have made measurements of RF power coupling in practice.

Jon (SDRplay marketing)