Saturday, March 09, 2024

SDRconnect Preview Look - The Server

As I mentioned in my first post about the SDRconnect Preview, I hadn't looked much at SDRconnect's server function. Today I have. Now, SDRplay are very good at making tutorial videos. How to set your RSP up as a server is described in detail here so I'll focus mainly on what I regard as strengths and weaknesses from a user's point of view. A few key points are worth mentioning.

  • The server can be configured for use in your internal LAN, or across the Internet (WAN). Say you have multiple PCs connected to a LAN in your radio room, then any PC can connect to the server as long as SDRconnect is installed. 
  • A LAN or WAN server will be set up either in IQ mode (corresponding to the IQ bandwidth of the RSP) or in Audio mode. IQ mode is obviously more useful in a LAN than in a WAN environment as it would require an extremely fast internet connection to sample say 10 MHz over the WAN.
  • Up to 8 simultaneous users are allowed, so you may ask: Can't I replace my KiwiSDR with this one? Take care though, because only the first connected user has full control of the RSP. Users 2-8 can tune around within user one's selected bandwidth, change modes, bandwidth etc but are at the mercy of user no. 1 not changing the frequency band.
  • Beware the dreaded CGNAT! No, I hadn't heard about it before either. Carrier-Grade NAT is a workaround for ISPs since the pool of IPv4 addresses is exhausted. When you set up your server, you have to look for the necessary public IP address. If you see something like the port numbers in section 2 in the image below, you are in trouble.

        There are workarounds, but they may be expensive. I won't delve more into this now, but the                   Internet  is at your disposal should you want to learn more.

  • After setting up the server and testing if connectivity is ok, it's time to get running. It is well described in the video I linked to above. My personal opinion is that it is unnecessarily tedious to start the server. Maybe it's a compromise because SDRconnect is multi-OS, I don't know. Anyway, after keying ".\sdrconnect --server", this window shows up on the PC hosting the server: 

  • There are loads of parameters one can use to set up the server, but you need to use the Terminal window for all this. It could be that you only need to set up this only once, in which case it may not be too much of a hassle. The last frequency range is remembered upon restarting the server, so you don't have to start on 100 MHz every time.
My own setup (which is temporary) is from a relatively cheap and modest speed fibre connection via a TP-Link router. The public IP address from my ISP is dynamic and will change over time, so I chose to use a dynamic dns provider. Everything on my setup is cabled.

Is the server stable? I haven't tested it long enough to tell. What I do know, is that if the router reboots, the server will disconnect. I have set the TP-Link to reboot every night, because I'm 170 km away from it, and consumer-grade routers are not 100 % fail-safe. It tends to "freeze" once every several weeks. A nightly reboot has proven to be a very good solution for 24/7 operation. It would indeed be nice if there was a workaround to provide server to restart and restore connectivity.

I have also had one instance of the terminal window not responding, resulting in a loss of connection and having to restart the terminal window. At this instance, both the local and remote PCs reported OK on the connectivity test, but returned an error message when actually trying to connect.

To end this post, here is a "panorama" of two displays showing two types of configurations at two different locations at the same time. To the left is the LAN (local, although it is labelled "remote") IQ client at the KONG HQ; to the right the WAN (labelled "internet") client at home, also running IQ mode.

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