SDR Front End Protection and Spin Modulation Fading
I have an SDRplay RSP1 that I’d like to use as a downlink receiver, along with an Arrow 146/437-10 antenna and Yaesu G-5400 az/el rotators. Uplink will be an Icom IC-7000. Using this setup, will the SDRplay need a Front End Protector to keep it from overloading? If so, which ones are recommended?
Also, I am considering upgrading the antenna to an Alaskan Arrow. Is there a noticeable improvement in antenna performance and gain between the standard Arrow and the Alaskan? Would the improvement in gain also result in deeper fading during spin modulation?
73, Mike, N8MR
Hey Mike!
I've used the SDRPlay RSP1 as my full-duplex downlink receiver for quite a while now and it works very well. (both FM & SSB sats)
Filtering is not a bad idea, but is not mandatory. In fact, the reason that I use the SDRPlay in this particular role is that it does much better against a 2m or 70cm uplink than the RTL-SDR or AirSpy R2 that I also have. Has no problem full-duplex w/ a 10m uplink for NO-84 PSK31 either.
-Scott, K4KDR
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-----Original Message----- From: Mike N8MR via AMSAT-BB Sent: Thursday, May 23, 2019 9:43 AM To: [email protected] Subject: [amsat-bb] SDR Front End Protection and Spin Modulation Fading
I have an SDRplay RSP1 that I’d like to use as a downlink receiver, along with an Arrow 146/437-10 antenna and Yaesu G-5400 az/el rotators. Uplink will be an Icom IC-7000. Using this setup, will the SDRplay need a Front End Protector to keep it from overloading? If so, which ones are recommended?
Also, I am considering upgrading the antenna to an Alaskan Arrow. Is there a noticeable improvement in antenna performance and gain between the standard Arrow and the Alaskan? Would the improvement in gain also result in deeper fading during spin modulation?
73, Mike, N8MR
Hi Mike!
The SDRplay receivers (all models) have front-end filtering across the range they are capable of receiving. As long as you aren't transmitting in the same band as you are receiving with an SDRplay, you should be fine. If you want additional protection for the SDRplay when working satellites, a 2m/70cm diplexer can be put in front of the SDRplay as another layer of protection. Again, the SDRplay is not protected if you transmit on the same band it is being used to receive. You won't need to run full power from your IC-7000 for satellite work. As many use Yaesu's FT-817s and FT-818s to work satellites, you will be able to scale back on the transmit power from your IC-7000. Once you get your station set up, you will be able to test and see how much power is sufficient.
I normally use an Elk 2m/70cm log periodic for my satellite work. For the SSB satellites, I must use a diplexer so the antenna is connected to both radios. I have used SDRplay receivers, a FUNcube Dongle Pro+ SDR receiver, and other radios (FT-817s, the all-mode receivers in Kenwood TH-F6A and TH-D74 HTs, and all-mode receivers like an AOR AR8200 and Icom's IC-R20 and IC-R30) in this manner. The diplexer is another layer of protection for whatever radio I use as a receiver, along with ensuring I never transmit on the same band I am receiving with the second radio or SDR receiver.
As for the Alaskan Arrow compared to the standard Arrow, you will have more gain with the Alaskan Arrow. You will have to be more accurate in pointing the antenna at the satellites, as the increased gain reduces the beamwidth from the larger antenna. With any antenna used at a fixed orientation, you will occasionally have fading that you'll have to deal with. Signals will fade out, then fade back in.
Good luck, and 73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK or http://twitter.com/WD9EWK
On Thu, May 23, 2019 at 3:35 PM Mike N8MR via AMSAT-BB [email protected] wrote:
I have an SDRplay RSP1 that I’d like to use as a downlink receiver, along with an Arrow 146/437-10 antenna and Yaesu G-5400 az/el rotators. Uplink will be an Icom IC-7000. Using this setup, will the SDRplay need a Front End Protector to keep it from overloading? If so, which ones are recommended?
Also, I am considering upgrading the antenna to an Alaskan Arrow. Is there a noticeable improvement in antenna performance and gain between the standard Arrow and the Alaskan? Would the improvement in gain also result in deeper fading during spin modulation?
73, Mike, N8MR
participants (3)
-
Mike N8MR -
Patrick STODDARD (WD9EWK/VA7EWK) -
Scott