Audio and Comm Console Development

by Steven K. Roberts
October 2, 2016

SKR aboard Maggie E - Sept 2016

Aboard the Maggie E, a friend’s Ranger 27 – enroute to Lopez Island on September 9, 2016

I catch myself doing it again: waiting for closure on some project before writing about it, an old magazine-freelancing habit. Something should actually be done before you publish the details, right?

Of course, this isn’t a single-threaded project. Subsystems and components are interleaved and interdependent, the objectives evolve with technological change (or at least my awareness thereof), and I’m working on so many fronts at once that I am always in danger of having progress overwhelmed by context-switching overhead.

All that is fun, but when it comes to blogging, old habits die hard. This post is an update from the perspective of 10 months aboard Datawake, and is focused on two console zones that are current work-in-progress.


The photos from my late-March Meet Datawake story reveal a stack of traditional audio mixer/equalizer units… basically a big funnel that gathers mono and stereo sources, combines them, processes them with effects and glorified tone controls, and makes them available as a master output for listening, recording via Thunderbolt, or other uses. This is SO boring.

auxbar-edgeActually, it’s worse than boring (marginal hardware quality aside). It’s also architecturally inflexible, and fails to address some of the more interesting applications on the boat. What I really need is a way to connect anything to anything, which is why we designed an elaborate audio crosspoint switching system for the BEHEMOTH bicycle and later Microship project. Those supported up to 8 simultaneous connections among any of 32 inputs and 32 outputs… although the Auxbar system shown in the photo couldn’t mix, distribute, equalize, or do anything other than perform clean, line-level routing (which was awesome).

I assumed during the gestation of this project that I would design a Node X to provide this capability… an Arduino with a long SPI shift-register chain driving a huge bank of latching relays, allowing switching with no “data type” issues (since simple relay contacts are bidirectional and work with audio, video, serial, PTT, sensors, or even lightweight power switching). But while offering essential functionality, this concept was poorly integrated with the mixer stack, so remained on a vague back burner.

But now, problem solved… and in my favorite way! Someone else has already done it really well, so I don’t have to spend a year inventing a partial solution. The folks at Guitar Center Pro were kind enough to accept a return of the unsatisfactory ART and Zoom boxes, then sell me some goodies from MOTU… the 1248 and 16A:

These things are lovely. They certainly aren’t cheap (Amazon 1248, 16A, & 24Ai), but they eliminate an entire development project while adding a rich web-based UI. A future post will explore them in greater detail… they solve that anything-to-anything problem while providing internal mixers, EQ, and Thunderbolt/USB host interface.

Of course, no learning curve or initial implementation is without glitches, and the first problem was that their free companion iPad app says, in the iTunes store: “The MOTU AVB Discovery from MOTU, Inc. finds all MOTU AVB Devices on your WiFi network, whether they are connected via ethernet or a computer with Thunderbolt or USB.” Turns out this isn’t true as stated, though I see its intent; in a system like mine with two MOTU interfaces, their Ethernet ports are tied up talking to each other… and they can’t be seen on the LAN (though they can via USB on the Mac, of course). One would have worked; so would three or more, using the AVB switch that I had to buy after all… and given that, my choice of the Focusrite OctoPre mkII Dynamic to add 16 more ports via ADAT light pipe was unwise since most of its value is in excellent mic preamps that I don’t need. So this goes back too, to be replaced by the 24Ai that I would have gotten in the first place had their marketing been accurate.

Anyway, the net effect of this mountain of professional overkill (worthy of touring bands and concert halls) is that now all my audio devices… about 40 sources and half that many sinks… will converge on this dense region in console zone Epsilon. Many of those are parts of stereo pairs, related to the piano/entertainment/recording; another group are microphones ranging from podcasting to security; a few more are computers; and a large cluster are radios and their various audio interconnects. There’s even a dedicated Pi for streaming to and from the Internet.


(AVB Routing Grid image from MOTU)

So here’s where it gets fun. Wanna talk on the Icom 7300 HF rig? Pull the boom condenser microphone to my face, poise my toe over a PTT foot switch, and tell the machine via app or macro that it’s time to play radio. The output gets routed to headphones, mains, or console speaker… and if I prefer to use the aero headset for noise reduction, well, we can do that too. Anything to anything, not five dangling microphones and at least that many speakers.

Or, perhaps I’m doing a YouTube video, shaping and de-essing my voice through the DBX 286s input channel strip, mixing in audio sources while talking about whatever… hydrophone, exterior mic, engine room sounds, recordings from the Mac or Tascam box, stingers, theme music, interviews, or radio chatter.

Or maybe I’m off visiting somewhere, far from the boat, and the system texts me to report a security violation. Red alert! Connect via VPN, check system status, watch the cameras including recent timeline, and mix together the interior microphones to discover that it was just Izzy batting a spider who was hanging out in front of a PIR sensor. Phew. (I know, spiders and boats… that sounds wrong… the photo below was aboard Nomadness, reminding me to get out more!)

This whole system is in progress now, with many cables yet to be made (and tested). Things like the piano and monitors are easy, but between this massive audio routing/equalization/mixing system and the cluster of radios I need interconnects… and here there be dragons. It starts with the line level from the mix having to become mic (or other “back panel”) level, ventures into the need for isolation of the balanced connection due to widely varying opinions about the meaning of “ground,” then wanders far afield with the need for filtering due to the fiendish nature of RF. I thought I was going to have to cobble together isolation transformers with level-tweaking pads and and then go crazy with ferrites and capacitors, but it seems this has been done well already by W2IHY… with a kit price of $59.


So speaking of the ham shack, let me bring you up to date on console zone Delta and its connected antennas. The N4RVE “maritime mobile” rig is becoming substantial, and my current mechanical packaging project is the somewhat daunting effort to cram five ham rigs into a 6U panel, then park all ancillary stuff on a 4U just above (with 2U of coax patch completing the comms cabinet). There is some bleed-over; the Home Patrol 2 scanner is next to the stereo in the audio cabinet, and the SDR devices (Funcube Dongle Pro and RTL-SDR, as well as a spot for the intriguing UDRX) are all located next door in the networking zone, hanging off the gigabit switch or the Nuc’s USB hub.

The core of this region is the panel o’ rigs, and what sounds like a lot of redundancy is really a nice spread of overlapping functionality (or that’s what we hams tell ourselves to ease the heartbreak of GAS – Gear Acquisition Syndrome):

  • 7300-filterIcom IC-7300 – the flagship of the station, this is a very flexible SDR-based rig that includes HF and 6-meters, with a rich touchscreen-based UI, excellent filtering, support for digital modes and external large-screen display, waterfall, SD card for recording, and lots of other fancy state-of-the-art features. This will be the primary tool, and owns a Diamond HFV-5 at the top of the radar mast (via the coax patch panel, so I can try other things if that turns out to be disappointing).
  • ic-m802Icom IC-M802 – the industry-standard marine SSB rig, FCC type-accepted for the marine bands, and channelized for ease of use. It works fine for ham radio, but has almost no knobs to twiddle and is kind of boring when you want to dig deep into QRM/QRN to chase something rare. This is piped to a PACTOR box a couple of versions back (new ones are way too expensive for my occasional need), and owns an AT-140 tuner and Shakespeare 393 vertical antenna pushing against part of the rail as a counterpoise. Even though it’s not mounted in the panel yet, I’ve been using this lately on 20 meters with good results.
  • ic-706Icom 706mk2G – a classic mobile, which also does multimode on VHF and UHF as well as HF… this rig I have had for many years, and think of it as a reliable backup. Ages ago, it was part of my mobile lab during speaking tours, and kept me amused during long drives. My original plan here was to wrap it in foil and pack it in a Pelican box for emergencies, but why not just build it in and add the potential for cross-banding or easy access when something fails… not to mention monitoring multiple things at the same time?
  • ft-817Yaesu FT-817 – the little QRP (5-watt) rig I bought about 10 years ago when working on the backpack technomadic toolset (here is the drawing). This is a much-loved little thing, and likewise ventures into the VHF and UHF bands… I expect to use it mostly for WSPR and other digital modes where processing gain can make up for low power; if it ends up living on one high HF band, it will probably own a thin wire dipole.
  • id-5100aIcom ID-5100 – finally, this is the most recent acquisition… a D-Star dual-band mobile with touchscreen remote head. With some reluctance, I sold my Kenwood TM-D710 to Steve Stroh N8GNJ to justify this purchase. By doing so, I gave up APRS and the data port, as this is the best 9600 data radio currently available off the shelf (thanks to the integrated TNC)… but I gained access to an Internet-linked network of gateways and reflectors. Damn trade-offs. I’m still getting to know the new rig, and have not decided yet if that was a mistake. Default antenna is a dual-band Rocky Mountain J-Pole, but this is via the coax patch panel so it can be swapped around if I need to use the Arrow beam or other tool.

APRS with Yaesu 290I might also need a 220 rig to engage with a geeky subset of northwest hams, but I’m out of console space and that would probably be tucked back in a corner. I’m also very tempted to devote my trusty old Yaesu 290 to embedded APRS. I’ve had this in my truck for about ten years, and it uses a stalwart old Kantronics TNC along with a Garmin GPS to transmit my location to other hams or the online tracking servers. In practice, I almost never use this while driving anymore, but it would be fun on the boat and easy to include. I also have the companion 790, which would pair well with another TNC for back-door control via handheld.

All this offers overlapping but differing capabilities, and the architecture of the audio networking system and independent antennas will allow simultaneous operation (whether with multiple people, or one human plus a few automated processes). For safety, their native audio outputs connect to a single dumb rotary switch in the middle of the cluster, allowing any to drive the single console speaker if all that fancy stuff has gone belly-up… or I just want to do the retro thing and not bring up computers as potent as yesteryear’s Cray to throw a few switches and twiddle knobs. It’s a sickness, I know.

weld-mount-tuner-at140Some of the antennas are up. The most recent installation was the AT-140 tuner for the M802 rig, mounted with the wonderful Weld Mount fasteners and 8040 adhesive to the hull. This pushes a 23-foot Shakespeare 393 mounted to port with the 409 kit, near the stern. There is an art to making a decent HF counterpoise on a fiberglass boat, and folks use sintered stainless under the waterline, clusters of wires cut for multiple bands, connections to tankage or engines, copper straps to thru-hulls, or… in my case… the stainless rail around the boat (safety issues duly noted, with testing required). Initial trials have only used the short segment from the port-side gate aft, but I’ve been doing well on 20 meters even with recent geomagnetic storms making propagation disappointing. I’ll go into much more detail about this and the other antennas in a future post.


Meanwhile, for keeping my ear to the ground, the delightful Uniden Home Patrol 2 is working well with its DPD OmniX antenna… a skyhook I was happy to find, as it doesn’t scream “scanner!” as does a discone. I had my heart set on the BCD-536HP for maximum feature set and DIN standard mounting, but my friend Steve bought the 436 and found the UI annoying enough to return it… and that convinced me to get this far more friendly rig. You can see at a glance what it’s doing, and management via Sentinel on the Windows box <shudder> was actually not as horrific as I imagined… once I got past the challenging evening of using the registry editor, installing an old version of .NET framework, Googling for hints in forums, and other things typical of a newbie stumbling into a well-established culture in which nobody even notices the absurd complexities any more.

With that, I’m going to pause before diving into the ever deeper pool of related material… there has been lots of other progress and the backlog of blog topics is getting scary (though I micro-blog on Facebook). It’s time to get out of back-screeching chair-slouching computer mode and do some more hardware!

Cheers and 73 de N4RVE aboard Datawake… hope to catch you on the air.


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