SO2R -- The hard way

This past weekend I had the privilege to be a guest operator for the Radio Club of America on their special event station W2RCA, celebrating the 100th anniversary of the RCA. The station was co-located with the anniversary event in Washington DC, and I wasn't able to attend in person, so the operation was handled using remote PC access and VOIP software, similar to the setup which I described back in late 2007.

A problem with remote setups is that they require a fast Internet connection to work well; the primary challenge being the speed (or lack thereof) at which you can switch from receive to transmit and back again. Because the W2RCA special event station was scheduled to happen during the ARRL's November SSB Sweepstakes, it was decided that we would work the contest as W2RCA. Being in a contest situation meant that rapid TX/RX switching would be a must.

As it turned out the network connection between my home and the RCA event location wasn't quite fast enough for the furious pace of the contest. I was having a hard time getting the remote radio keyed quickly enough to bust the pileups. In some cases I would bust the pileup only to have the target station get frustrated because I wasn't coming back to him fast enough. Not good, not good...

Out of curiosity I turned on my home station and tuned to the same frequency as the W2RCA remote. I found that despite being separated by 2,500 miles I could hear the target station well on both radios! Not wanting to give up on the contest for lack of fast TX/RX switching I decided to try an odd twist on SO2R (Single Operator-Two Radios) setup. I activated transmit on the W2RCA remote station, muted my microphone, and plugged my headphones into my home station. Because SSB is carrier-less mode the remote radio would not transmit any power with the microphone muted.

The next time the target station called QRZ I unmuted my microphone and called him, and heard him come back to me on my home station! I was able to work several stations this way, although there were still a few challenges. First was the effort of keeping the frequency of ftwo radios in sync. Second was some of the stations I could hear clearly on my home station were outside the range of the W2RCA remote station. But in general it worked and was an interesting way to get around the slow TX/RX switching issue.

TS-2000 Remote Control w/ Audio

One of the fun but also useful capabilities to have in your shack is the ability to run your rig remotely. I decided to do this for my Kenwood TS-2000 since it's basically a radio wrapped around a computer and has a zillion interface options. Kenwood makes ARCP-2000, a remote display program which frankly isn't worth the $250 they ask for it. Ham Radio Deluxe (aka HRD) is a great program; it's feature-rich, highly configurable, and best of all free. You can run it over a screen-scraper like VNC, Remote Desktop, or even X-Windows. A better solution is to use the HRD remote access system; this essentially allows you to tunnel serial data to your rig and control it via a remote instance of HRD.

Two challenges exist here; publishing the HRD server over the Internet without open router firewall ports, and creating a high-quality and stable audio path.

Dealing with the server question first; I absolutely do not recommend opening holes in your firewall. There are a lot of solutions available which eliminate that need. I use Hamachi which has an additional benefit in that the clients are coordinated via a central server so a static DNS is not required. I simply point my remote HRD instance at the private IP assigned to my home system by Hamachi and I'm connected.

Getting quality audio across the Internet used to be a challenge, but after using Skype this year for business I think it's ready for prime time. I created a separate Skype client ID intended only for receiving inbound calls from me when I'm remote. I set Skype to auto-answer, and point the audio paths to my rig's sound interface.

Detailed diagram of my setup is available here.