Loft Receivers v2…?

At the start of my Loft Receivers project there were two obvious approaches to the system architecture:

  1. A loft-based PC running SDR hardware and applications, access this PC via remote desktop method over network (VNC/IPSound)
  2. Loft-based SDR hardware, I/Q outputs streamed over network, SDR applications running on remote PC

Option 1 has been the focus so far due to the relative ease at which it could be assembled using spare PC hardware.  In a number of ways, Option 2 presents a more elegant system (cheaper total system cost, lower power consumption, lighter network footprint…),  but I expect it will demand much more configuration time.  In that respect, Option 1 is conceptually simple – set up a basic SDR PC then connect to it via VNC/IPSound.

In reality there has been a lot of trial and error in getting the Option 1 station up and running and I am still trying to optimise the performance for data modes reception.  With the extra overheads of running VNC and IPSound I may be hitting the limits of the Loft PC’s modest specification (Athlon64 3000+, 1GB RAM).  I had thought this would be plenty enough for the job but perhaps I was being optimistic.  If this is the case, I’m loath to spend a couple of hundred pounds on upgrading the PC’s motherboard/CPU and RAM for what was meant to be a “low cost” project…  Additionally, Spring has arrived and the temperature up in the loft has suddenly risen giving me concerns that it may be difficult to run a full powered PC up there during the summer months.  These two factors may combine to see Option 2 be taken up sooner than expected.

This could be a nice project to put my Raspberry Pi to work.  I’ve read somewhere about using a Raspberry Pi for sending the RTL-USB dongle’s I/Q output via TCP and SDR# can receive this.  The SoftRock Ensemble II receiver would need a USB soundcard plugged into the Raspberry Pi and then the Pi will need to be configured to send the line-in out over the network using Pulse Audio or something…  A quick search shows a promising guide:

My next steps on this project are to temporarily set the SoftRock receiver up on my more powerful desktop PC (Intel i5, quad-core, 8GB RAM…), access this via VNC and see if the performance difficulties disappear with the extra muscle.  If it continues to be a struggle I expect some RPi action to commence shortly…!

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