so what happening when you switch ignition off?

 

The Carnetix P1900 DC-DC power supply has a startup-shutdown controller, with power sequencing. This means when I get out of my car, and turn it off, it will send a signal to the Mac Mini and put it in "sleep" mode. It will then bring it out of sleep when I get back in the car and turn it on.

Waking up the Mac Mini is usually < 2 seconds.
It only uses 2 watts when in standby !!

 

Most people that end up with a CarPC go the 7" 16:9 touchscreen route, usually with a 4- or 5-wire resistive touchscreen... Lilliput and Xenarc are the popular brands. I've been frequenting MP3car for the better part of a decade, and have lost count of the number of projects that used these screens... probably in the hundreds or thousands, easy.

(example of the "status quo" carPC, in the wild)

I wanted to go another route.
Why not ditch the touchscreen and go with a simple monochrome LCD and some knobs/buttons?
It is a MINI Cooper after all. No need to check e-mail and weather while driving...
I like to drive for the sake of driving... Minimalism at its best.


My idea was to interface a very simple monochrome 2x40 character LCD to an Arduino, along with a few knobs and buttons for volume, track select, etc. This would allow me to:
(A) keep the philosophy behind the car... motoring, not web surfing.
(B) avoid a lot of the common pitfalls that come with hacking up your dash and installing a non-transflective, 4-wire resistive touchscreen, with a non-standard resolution..
(C) keep costs down.

However, I finally decided to go with the LCD display for a very important reason that I'll explain in a later post. For now, I'll say that there's a very particular software app that I am in the process of developing that basically requires a TFT display... it's pretty awesome, and I can't wait to show it off

Here's the criteria that I used when selecting my display. Keep in mind that I've spent a good part of my career working with a team that designed glass cockpits for aircraft use. I'm very familiar with the technology and know what it takes to make a daylight-readable display.

• Form factor: Must be 7" diagonal, 16:9 aspect ratio. This is so that it can fit into my Metra double-din dash kit.
• Resolution: The first requirement pretty much limits resolution to 800x480.. however many of the new displays will allow the computer to drive a higher resolution, and downsample to the physical 800x480 pixels. I made sure to select one that had this feature.
• Brightness: 450 nits or higher. 500+ would be preferred. There are quite a few displays down in the 250 to 350 nit range. Steer clear of these unless you live in Alaska, or are very broke and want to cut your teeth in the CarPC realm.
• LCD technology:IPS would be nice (like all the pretty Apple screens), but TN is all you'll find in this market
• Transflective vs transmissive:Transflective is HIGHLY preferred for daylight readable displays. However, they're expensive. This is what they use in the military / avionics markets. Transflective screens look great in sunlight; transmissive displays do not.
• Capacitive vs resistive touchscreen:Now that capacitive screens are readily available, I'm adding it to the list of my requirements. No resistive touchscreens for me. Capacitive screens don't block light, as they're simply a piece of glass. Resistive touchscreens will wash out your image in daylight.

The 7" LCD display market has pretty much stagnated since 2008. Nothing really new out there, with a few minor exceptions. Transflective and capacitive touch displays are finally readily available. Two sites that stock them: Mobile Computing Solutions - Innovations in Mini ITX and http://motorcitytech.com/.

I opted for the following display:

Motor City Technologies - Capacitive Multi Touch Lilliput 669 HB in Double DIN Frame
It's based on the Lilliput 7" High Brightness HDMI Monitor 669GL-70NP/C-H, and has been upgraded with a capacitive touch kit, that supports multi-touch (the jury is still out on Mac OSX support, we'll see). It's 450 nit LED backlit, and has been installed in a Bybyte Double DIN Frame. It has the Auto Switch mod for reverse camera option, and I'm pretty sure it has the auto-power-on option.. if not, no big deal, it's easy to mod.

Here's the monitor that the kit is based on (Lilliput 669GL-70NP/C-H).
This monitor is used a lot by the live-video Canon 5D / 7D guys. If there was a linear equation with "Cheap" and "Good", I think this LCD would hit the cross-point.

Here's the Double-DIN frame that the LCD comes installed in. It's from ByByte.com, another interesting CarPC niche company.


The display has been ordered, I'll report back here with results on how it performs in the bright Florida sun.


Next up: Software!

 

I wanted to go another route.
Why not ditch the touchscreen and go with a simple monochrome LCD and some knobs/buttons?

Heh, I did this on several builds around 2000-2002. WinAmp, I remember, had some parallel and serial interface plugins that made input pretty easy, and a lot of players/front ends support multisegment displays. I have a pic somewhere...

Anyway, I haven't read this thread in detail yet, but I look forward to see how you plan on implementing the DSP! I tried the same thing in Simulink, but had a lot of issues with lag, CPU usage, and artifacts (I use it in 2ch mode for other sig proc. applications without much problem, but like you, I need 8+ channels of processing). This is why I went to VST, but that's a tough deal on a Mac. However, there are some linux VST hosts that I see around (Jack?) that might work on OS X, and there are a lot of good plugins that have Mac versions (Voxengo's suite, for example).

Edit: [the Voxengo crossover/EQ I use is FIR too, I believe, which would work for your app...]

 

Are you adding cooling for the Mac Mini?

 

My glove box and secret compartment are air-conditioned Hope that does the trick.

 

Earlier I mentioned that I've been completely fed up with the various car DSP's out there, both the vaporware ones, and the tried-and-true ones. Here's a quick rundown the features that I would require:

• More than 8 channels. 10-12 would be nice.
• Center channel extraction. I need the ability to run a separate center channel in my dash. This is NOT the same as simple "Left+Right"; I'm talking about TRUE center channel extraction here, which requires ACTIVE MATRIX decoding. Left+Right is only PASSIVE MATRIX, which only provides 3 dB of isolation.
• Rear channel extraction and delay. Same as above. Left-minus-Right delayed 20ms is NOT what I'm looking for here. Active matrix decoding is required, and furthermore, I'd like to tweak the parameters to suit my needs.
• Linear-phase FIR filters with VERY long taps. This requires a metric ****-ton of CPU processing power. Every single car DSP out there uses IIR filters (with the exception of maybe one), which I consider to be a compromise. I can do some incredible things with FIR filters, given the processor resources needed.
• An auto-tune that works. More on this later.
• Double-precision floating point math for the entire processing chain. That is, no integer-based DSP's, as MANY current car DSP's use integer-based math.
• Ability to use a custom DAC. I'm currently drooling over the ES9018 Sabre DAC by ESS. Something like the Twisted Pear Buffalo III board.
• The above requirement would allow me to run 8 channels at up to 32-bit, 384 kHz. Not that I have any music encoded at that rate... but might come in useful for something.
• Ability to run full-digital from my collection of high-bitrate MP3 and FLAC files, through the DSP, right to the DAC. I don't see why I should go from digital-to-analog, to digital and then finally back to analog, as most folks do with their CD player.
• Complete ability to tweak any/all settings. This clearly excludes the MS-8.

Out of the requirements above, the JBL MS-8 comes damn close. However the last requirement (ability to change/tweak any/all settings) is completely lacking. So it's out like the Monday trash.

On the topic of the center and surround-channel stuff:
Here's a quick rant on why I consider active matrix decoding so important.
(this was an IM that I sent to the lead manager of a car audio company's DSP project... needless to say, I got no response back )

Extraction of a center channel requires more than simple L-R or other rudimentary math (ie not possible to implement with the PS8 mixer afiak). Here's a link to a paper that explains it pretty well:

http://decoy.iki.fi/dsound/ambisonic/motherlode/source/sur.pdf

There are a number of reasons why I think this would be very beneficial for a DSP to support this feature:

- If you use a center channel, both front seats will sound the same and the image will be great for rear seat passengers too.
- Two-seat judging obviously becomes a lot easier for SQ events. More of a "slam dunk", really. More trophies for you guys to take home
- There are a lot of new cars that come with a center channel and side/rear channels (BMW et. al.). Not everyone is an SQ purist, i.e. not everyone would be okay simply disconnecting these channels. I find it hard to believe that the "rich guys" that walk into a shop and want "the works" done to their cars wouldn't want to keep all of their existing speaker locations.
- Seat position and angle become a lot less important for proper imaging. You get a lot more than a simple "sweet spot".. Theaters have known this for years and years now.
- For center channels that with tweeters that go up to 20 kHz, it seriously improves one's chances at getting the center to image properly; I've found it's extremely difficult to match the left and right tweeter to get a proper center image; there's a thread on Diyma I can pull up where Patrick Bateman was experimenting, and found found this out, even linked to some research papers that backed it up with numbers. Again, once this tweaking is done with a two-channel system, it sounds like crap for the other passenger, i.e. a compromise).
- Small cars, like my Mini, are IMO a lot harder to nail with two-channel systems, due to extreme differences in path lengths. There are a lot of people buying small cars these days, which IMO makes nailing T/A and Eq that much harder. Adding a center channel and proper matrix decoding is a very easy solution.
- There are no other processors out there, except for the MS-8 (via L7 active matrix decoding, which is proprietary to Harmann/JBL), that do center and rear fill properly, and everyone knows the MS-8 is a half-polished turd.
- Proper rear-fill (delayed ~20 ms to overcome HAAS effect, and phase-steered and Eq'd) can add to stage "width", although SQ purists would consider this cheating. I've played with this in my car, and absolutely love it.
- Properly mic'd and mixed SQ CD's sound absolutely great with the matrix surround decoding. I run my home system this way, it sounds fantastic, I can give a list of tracks to demonstrate if needed.
- There have been PLENTY of SQ competitors in both IASCA and MECA that have used center channels and proper rear-fill over the years, even if they're completely secret and haven't told anyone... And they've taken trophies for them.

As I've said in other threads, I'm sort of in the vocal minority here, because most SQ purists don't believe the stuff above, and frankly are content with what they have. Well I don't listen to CD's. I frankly don't know how any self-respecting audiophile would (dons flamesuit). I absolutely love what Dolby Pro Logic II and Harman/Lexicon Logic7 can do to the listening experience in my car. So there's not really a market for what I'm proposing above. I understand that, and am actually kind of excited that I get to try to write a DSP myself... they're certainly challenging, so it should be interesting to say the least.

So, here's a quick outline of the method that I will use to implement my own DSP.

First and foremost, I will be writing 98% of the DSP code and user interface with National Instruments Labview.

My reasons for using Labview are as follows:

• It's what I use at work. I'm very, very proficient at it.
• It's perfect for designing complex applications with tons of input, processing, and output.
• It's perfect for Rapid Application Development. In english, this means you can use it to get **** done
• It comes with a very complete set of mathematical and scientific functions (filters, FFT's, etc). This means you're buying a loaded Matco toolbox, rather than a swiss-army knife.
• I already own a college edition, and this DSP project will be for purely educational purposes.
• It includes an excellent library of user interface objects, including XY graphs, plots, buttons, and sliders.
• Although not truly "Real-Time", Labview is fast enough to keep up with audio DSP stuff. There's even a free set of courses at cnx.org (Rice University) that teaches DSP music synthesis using Labview.
• Programming is graphical and does not involve writing code and dealing with syntax. This improves readability, and speeds up the coding process considerably.

Propaganda shot from National Instruments, showing the "Power of Labview"

Picture of the Labview block diagram pallette

Here's a list of functions that my DSP will support:

• Time alignment for each channel. Time resolution will be the reciprocal of the sampling frequency, just as it is for all other DSP's.
• Linear-phase FIR filters with very long taps... As opposed to IIR filters used by 99% of the DSP's out there. This goes for both crossovers, and equalization, and gives me the utmost flexibility. I'm perfectly able to use IIR or other filter types if I do so choose.. but FIR is the current plan. This should also allow me to change crossovers and equalization without having to re-do TA.
• Full support to graph out impulse responses, step response, etc from any of the DSP building blocks. Being able to see the filters
• Full surround sound processing as mentioned above, similar to Dolby Pro Logic II and/or Harmann/Lexicon Logic7. I've basically read the patents, and will be implementing my own algorithm in real-time, which processes the incoming 2-channel data into 5.1 channels (left, right, center, rear-left, rear-right, and subwoofer). I will be writing another thread on this topic at a later date, the patents contain some very cool stuff.
• I will use FFMPEG and/or other libraries to decode the FLAC and high-bitrate MP3's, and convert them to a two-channel array in memory that will get sent to the DSP algoritihms.
• I plan on using a CD extraction library, similar to what CD ripping utilities and ExactAudioCopy do, for the times that I must use a CD... like for IASCA and MECA events. The bits will stay in the digital domain from the time they're read by the laser, to the time they're converted and sent to the amplifiers.
• Once the DSP numbers have been crunched, the floating-point arrays are quantized and output directly to the sound system using a Labview library function.

And another feature that I'm very proud of... The ability to do RTA and log sweep FFT's similar to HolmImpulse and others... all from the CarPC, in Labview. I've already got this code up and running, and it's a lot easier to use than TrueRTA, and it actually works in Mac OSX, no need to boot into Windows. I'll post some screenshots at a later date, when the bugs have been fully ironed out.

Most of my time over the last few weeks has been spent reading various DSP and filter books... Here are two that I liked at lot, as they are both written quite well, and are straight to the point:






Next post will be about the multi-channel DAC that I will be building. Will hopefully get around to that tomorrow.

 

Niel, I'm not going to pretend I understand the tech behind all this but applaud the incredible dedication and less-traveled path your taking; let alone willing to share it with us. What you have written makes pratical sense and the choices you made, assesed and re-made certainly help us/me understand.

Earlier I mentioned that I've been completely fed up with the various car DSP's out there, both the vaporware ones, and the tried-and-true ones...


...As I've said in other threads, I'm sort of in the vocal minority here, because most SQ purists don't believe the stuff above, and frankly are content with what they have. Well I don't listen to CD's. I frankly don't know how any self-respecting audiophile would (dons flamesuit)...

+1 to the above. Even though I must admit that I fit in that pigeon-hole, except I'm not an audiophile or SQ purist and I do listen to CD's, but don't actually worry about the format, I have PC based music, LP, CD's, tapes... hell I'm on the look out for a working 4-track or 8-track player.

Why??

I'm throwing this one out, and wonder if in a way we both (and perhaps a few of here too) like music, first and foremost. Then, comes the technology both passive and active behind it all... pleasure comes from creation, be it the music itself or the tech driving it. no?

 

Dude. Wow.

 

Definitely sub'ed to this one.
Attention to detail so far is awesome.

 

Have you seen his car? I wouldn't expect anything less...lol.

 

I wish I knew more about this sort of thing. I'll be reading it but not understanding
half of what you have going on. What is cool to me is the amount of eq, xover, and
TA you get out of these things. Prolly the only thing I would ever replace my XES
with.

 

In my limited experience, the amount of Eq, TA, and such that is needed totally depends on the car. Large cars have more equal path-lengths, for example, you can mount in the kicks. You cannot mount kicks in a MINI, there's no room. You end up with really crazy reflections and weird standing waves in the bass frequencies due to the small dimensions. You're more "near-field" than you would be in a large car, as you're even closer to the reflective surfaces.

So TL;DR is, Equalization and other DSP is not a panacea as many have said... but it might level the playing field in some cars, like mine.

This project is also one of those "what if" kind of things as well, just another challenging project to flex the brain muscles. The state college system is f*cked here, I consider the DIY approach a MUCH better way to learn. It's definitely more hands-on.

 

Estimated CarPC Costs so far:

• $599 - Mac Mini A1283, back in 2009, from the Apple Store
• $100 - Apple Airport Express base station
• $129 - Carnetix CNXP1900 DC-DC power supply & shutdown controller
• $26.20 - Carnetix CNX-P5V 15-watt 5V addon for CNXP1900
• $349.99 - 7" Lilliput 669 LCD TFT with capacitive touchscreen and double-DIN frame
• $29.99 - Metra Double-DIN dash kit for MINI Cooper R56
• $100 - 128GB Solid-state disk drive for Mac Mini, via newegg
• $100 - 2x PC3-8500 2 GB RAM Chips for Mac Mini, via ifixit.com
• $20 - LabVIEW 2011 Student Edition
• $150 - Estimated costs for custom LCD display and knobs (user controls), and Arduino interface
• $200-$1000 - Estimated costs for custom DAC board and raw parts

Estimated total: ~$2100 or so....

Ehh Anyone who says CarPC's are cheap, are lying or ignorant.
Apple CarPC's, doubly so.

 

Still though, for an equivalent 12v full blown SQ system that will do what your going to be able to do its a great alternative. Plus all the "other" things you can do with it that you simply cannot do with, say and ALPINE F1 just doesn't really compare. Way back in the day when I purchased my Sony XES system I think I paid something like 5650 give or take a couple hundred. And this was 1992 or so prices. That is pretty damn pricey however, to me I consider it a bargain because I still use the very same system today. It doesn't do near what your able to do or everything I wish it would. But it still works and sound pretty dang good for something this old.

I would still like to build a system like your doing, plus I have a really small car like you. Prolly even less room. I'm sure I'll learn a great deal from your thread and I look forward to it.

I had the very same results as you with an MS-8 I installed in a buddies car. After using my system for so many years and TRYING to get near the same results ouf of the MS-8 was impossible and its 20 years its senior. I tried every little trick I could find on this board and others, it lacks so much tune ability and adjustability, plus the use of that silly mic. The difference was night and day. Don't get me wrong if I had some expensive new car and had to keep the head this would be an option. However with other companies now making products that can also be used like an MS--8 I think I would rather try something else. SORRY FOR THE DERAIL of sorts.

 

Wow. I got to your description of the functions you plan to implement and immediately felt like 5 year old trying to do Calculus. You are taking this to a ridiculous level (in a good way.) I can't wait to see where this goes.

I quit programming (BASIC and Assembly on my old Color Computer 3) when my dad bought a PC back in the late 80's. Makes me wish I'd stuck with it.

As much as I love car audio and want to have an exceptional car stereo system, I can't see putting that much effort into it. It doesn't seem like it would over come all of the car-related problems (engine noise, road noise, PLD's, etc) to make it worth while (to me).

If I ever end up back down in FL for any length of time, maybe you can prove me wrong. LOL

Can't wait to see more.

Jay

 

Here's a picture of the stock dash in a 2011 MINI Cooper (not my car), just a random internet pic:

Notice how the radio is built into the speedo. FREAKING GENIUS guys :laugh: This is one of the many reasons why working on MINI's are so challenging. The BMW engineering team certainly had their heads up their collective asses on that one.

So what do us "DIY" guys do when we want an aftermarket radio?? Well, most use the Metra kit for the '08 thru '12 MINI Coopers that allows the installation of a Double-DIN radio:

Take notice of the little piece on the lower-right. That's a "black-out" plate that goes where the speedo LCD and knobs used to be. Great... Now my brand new car looks like this:

(yes, that's actually my car, it's dirty and I've got a lot of work to do).

Notice the Metra "Black Out" panel in the speedo area where the radio controls and display used to be. Yuck.

Here's what I'm going to do to rectify this situation.

• Take apart the "stock" display and controls that reside in the speedo housing
• Take apart the "stock" single-DIN radio that resides in the center lower console
• Try to reverse-engineer the knobs and buttons
• Try to source an alternate LCD display to replace the existing one (VERY unlikely that I could reverse-engineer the protocol of the existing one).
• Use an Arduino to interface the LCD and the buttons/knobs to the Carputer.
• Write some software in Labview that talks to the Arduino via the USB-to-serial bridge. This will allow the CarPC to send text to the display, and read the buttons.
• While I'm at it, use four extra pins on the Arduino to interface the steering wheel radio buttons: Vol Up, Vol Down, Track Left, and Track Right.

So I ripped apart the stock pieces, here's what I came up with:

The existing LCD is a graphic monochrome type amber-on-black. Hard to reverse engineer... hard to source a replacement.. Hard to program even if I had a spec sheet. Instead, I went with a 40x2 character LCD, the type like you'd see on any niche-based product that didn't have the money to source a "real" LCD..
Here's a picture of a similar LCD to the one I ordered:

The actual LCD that I ordered was from Futurlec, it's red-on-black, but otherwise perfect. Simple parallel TTL interface that I can easily interface to an Arduino. I will likely replace the red LED backlight with an orange-amber to completely match the rest of my interior.
REDLCD40X2BL - 40 x 2 Red on Black Character LCD Display with Backlight

For anyone that doesn't know what an Arduino is, it's the latest boner in the DIY microprocessor scene.

It easily allows average Joe's like me to interface digital inputs and outputs to a computer, and much more. I've already got four Arduino's in the MINI Cooper already, in my amp rack.. check out my build log for more info.


So as complicated as all this stuff is, this will allow me to keep the "stock" look and functionality of my interior. This will make it very easy for IASCA and MECA judges to operate the controls, and will hopefully award some points on the install (getting "all" of the points would be nice too, with the amount of work I'm doing!). Having a monochrome LCD up in the speedo is nice, since it's more readable in daylight, and provides more of a "Heads Up" than the TFT display would be. As I've said before, I'm a knobs-and-buttons kind of guy. Changing the volume on a touchscreen is a pain-in-the-ass. There's simply no way that I could do this build with just the touchscreen controls.

When I'm able to reverse-engineer the buttons and knobs, I'll post that info here.

 

this is gonna be awesome.

sub'd.

 

This is gonna be seriously cool, that is not DIY , this is as professional as it gets.

 

Well, yes. FIR filters are cool.
But you can not substitute acoustics with electronics. If you have had problems with the sound using MS-8, how do you really know it's MS-8 and not speakers placement?
Some would say investing time&effort in sound absorbing roof lining is better idea then having speaker phase super-precisely aligned...

 

Well don't worry. :laugh:
I am not substituting electronics and DSP algorithms for good acoustics.
My DSP is just ONE TINY PIECE in the whole project... It was never intended to cure cancer and end wars.

I've talked a lot about this in other threads. I agree with most of what you're saying. In a car, being near-field, the reflections will totally screw phase up. I realize that using linear-phase FIR filters will not "fix" the phasing problems that come from a reflective environment. However, I agree with Patrick Bateman, and others, that there is a certain threshold where phase can be heard (there's a chart floating around the internets somewhere). This has been talked about in other threads, I don't want to go in depth about it here. There are other benefits that come with FIR filters, I may go more in depth when I can. FIR filters do not have to be linear phase, but it just so happens that most of the filter types happen to use linear phase, because they can

As for the comment of the MS-8... I know that it gave me a crappy tune because i used my ears. Once I got the Mosconi 6to8 installed, I was able to tweak it to my heart's desire and get a good tune. Now I'm having some fun and learning some stuff, and I'll have a cool DSP to show for it. Don't get me wrong. The MS-8 is great if your expectations aren't high. But you can't exactly walk into IASCA and/or MECA and walk away with trophies with it.

And FWIW, I will be re-locating my mids to be closer to my tweeters, in December. And will be adding various acoustic treatments to my car in the coming months. Lots of work left to do...

 

This is, again, both awe-inspiring and jealousy-creating.

Regarding the 40*2 dot screen, I wonder if you could get a white backlight one and use colour filters to match the amber. But then again, that would be too easy, wouldn't it?

 

Regarding the 40*2 dot screen, I wonder if you could get a white backlight one and use colour filters to match the amber. But then again, that would be too easy, wouldn't it?

I bought about 1000 3mm Orange-amber LEDs a year or so back for a defunct project, most of which serendipitously ended up in the amp rack. I could just see how it turns out after changing the backlight LEDs. I also bought some orange-amber color-correcting gels from B&H Photo, in an attempt to make my JBL MS-8 display match my interior (I'll dig up the thread on that one later when I'm not on tapatalk, I even did a YouTube video on it). I could instead use white LEDs and use the gel.

Edit:
JBL MS-8 display color Thread: http://www.diymobileaudio.com/forum/fabrication-tools-tricks-trade/116410-i-want-my-ms-8-display-red-2.html
Youtube video:

So I'll likely try it both ways and see how it ends up. I was at least lucky enough to find the "negative" black background type of polarization in the model I ordered.

 

I think I remember that thread. Now that you mention it, would you happen to have a good and cheap source for polarized filters? I have an OEM lcd screen in my other car which has black lettering on green background and have been thinking of changing it round for a long time.

Here's a lousy phone camera pic of it.

 

Just curious but wouldn't this take years of coding? You are attempting to write code for like 5 different program algorithms that other companies have spent hundreds of thousands of dollars doing R&D for.

I am amazed but puzzled at the same time. I am very interested in anything Car PC however and I wish you nothing but the best of luck. Nice to see people thinking outside of the box.

I went full size PC and with everything on in Audiomulch I see around 12% CPU usage with the T/A, Xovers and EQ (they aren't on linear phase mode as I wasn't able to equalize the delay).

Have you seen this? Check it out. ARC System 2

 

Just curious but wouldn't this take years of coding? You are attempting to write code for like 5 different program algorithms that other companies have spent hundreds of thousands of dollars doing R&D for.

I am amazed but puzzled at the same time. I am very interested in anything Car PC however and I wish you nothing but the best of luck. Nice to see people thinking outside of the box.

Lol, no :laugh: I'm writing it in Labview, it's already written all the important stuff for me. Just off the top of my head: FIR filters, IIR filters, FFT's, other types of transforms like the Hilbert and laplace transform, windowing, queueing, semaphores, array handling, graphing functions, audio input and output libraries, file I/O, tons of user interface objects, and most importantly... The most comprehensive multi-threading support and multi-processor support that I've ever had the opportunity to use.

So like I said in the OP, it's sort of like a fully-loaded Matco toolbox, as opposed to a swiss army knife. You could use either to build a house, but I'd prefer the former.

The reasons like Arc, Mosconi, and JBL have taken so long is that they're trying to stuff it down to a tiny little DSP that's written in a combination of C/C++ and assembly. VERY low-level stuff. Instead, I'm using a $2000 off-the-shelf computer with a $3000 MSRP rapid-application development system... Overkill, but it works. Apples and oranges.

I've used Labview at work over the last ten years now, and I've done some truly amazing stuff with it. I've written code that has been used to test and verify GPS receivers, autopilots, NAV/COMM radios, transponders, and collision avoidance systems. All have involved lots of data throughput, simultaneous threads executing in parallel, all in real-time. I don't forsee any major road blocks with the DSP project.

I'll very likely have a very rough demo available in the coming weeks... then go back and add in all the bells and whistles.

 

So, the Labview is a pretty high-level development tool, right?

Then how do you think it can compete in terms of speed, memory efficiency etc, with some lower level developmets, like C++ or similar?

From my area of expretise, universal systems are always slower/more demanding compared to specifically developed tools. Are you going to have some sort of compiled version of your DSP?

 

Labview is very a VERY high-level development system.
It is comparable to MATLAB in certain aspects.
However, Labview is MUCH faster than MATLAB and other high-level tools.
Unlike Python and others, Labview is strongly typed, which helps memory usage and processing speed.
Like Python, the environment will compile the high-level code, and keep the compiled version until the high-level code is changed again. This means it's not "run-in-time" like Visual Basic, which compiles-on-the-fly (one of the main reasons Visual Basic is slow).
Since the price tag is high, NI has had the funds to optimize Labview for individual processors and other architectures.

Lastly, it's important to remember that 99% of the processing power in DSP is in the processing of filters and other signal convolution-type stuff. And all of this is done in Labview through pre-existing library calls to low-level (C/C++ or assembly) calls. If you open up the "FIR filter" VI on a Windows machine, all you'll see is a call to a National Instruments DLL. Since these highly-used, CPU-processing intensive functions are all highly optimized, there's very little to worry about the overhead of the rest of your code.

So TL;DR is, Labview is a great choice for writing a quick-and-dirty DSP

 

How are you going to sort out preringing?

These days it's a stumbling block for all of developers (Audiolense, Acourate, etc.)

 

Sorry to say, I'm not quite sure yet I'm still quite new at this, and am admittedly not a filter design expert. The only saving grace is that, I have 100% access to all of the filter kernels that I will be using, and therefore have the ability to look at them in any aspect that I wish, e.g. impulse response, step response, frequency response, etc., via all sorts of XY graphs, charts, voiceprints, 3d waterfall, etc., all inside the Labview environment. And it helps that I have access to books and papers, and the internet, and discussion forums. In fact, I'm glad that people here are being skeptic already It keeps me on my toes, and makes sure that I'm not over-looking anything.

My un-educated guess is that a lot of problems go away with longer filter kernels. I'll have many opportunities to play with various methods and strategies. Worst case is, I can always revert back to IIR, either temporarily or otherwise. That's the brilliant part about having complete control over the whole project. The only thing I'm limited by is my own mental capacity, and CPU processing power, to some extent.

Thanks for your input so far, ansuser

 

Neil_J,

I am not going to discourage you.
I am really interested in all this convolution stuff as well, for my planned home audio set-up. And the more I look for simple ready solutions, the more I see that it is not panacea and not as straight forward in day-to day usage as dedicated standalone HI-Fi equipment. Some people already utilizing GPU acceleration, but still far from ideal solution.

For me, the issue with your plan is that you are trying to put together a pretty powerfull but complicated toolbox while not having identified the problem exactly. There is a possibility that simple physical action to you car space can do much more and in much more effective way compared to FIR filters.
For example - consider the sub sealed box. Even though sub walls are very rigid, it is very desirable to avoid standing waves inside the box. So, max inner box dimension should be smaller then 1/4 HP wavelength (HP=100 Hz, => size<0.8 m). If you overlook it, you will get an amplitude bump and a phase shift in response. And I guess it will be tricky to correct digitally.

After all, I'm not trying to say that you won't succeed. You will, especially taking into consideration your very good skills and motivation and attitude. But I'm afraid that technology you rely on can fail.

 

i am glad i spoke with you on the phone about the car pc stuff.

i will be here if there are anymore questions - but you seem to be leaps and bounds further than i am neil.

anything i can do to help - just let me know

 

Awesome stuff. Thanks for sharing your project with us, Neil! I know that we'll all learn a sh!t ton from this project, and that to me is priceless.

 

Neil,

Don't know if you've already purchased the M4 SSD, but if you want to bump it up to 256GB, Buy.com has it for $159 with free shipping. I also really like the Samsung 830 Series SSDs.

Buy.com - Crucial M4 256GB 2.5" SATA III Solid State Drive (SSD)

 

Love the creativity! This will be an incredible build to watch.

 

So the Arduino Due came out today, this should be perfect to interface all the bits and pieces of my system:

- 2x40 LCD in the speedo housing
- knob/button cluster in the speedo housing (vol, track l/R, Mode, etc)
- steering wheel controls (vol up/dn, track L/R)
- serial control of the amp rack Nixie displays
- serial control of the amp rack LEDs
- individual on/off control of amp +12V turnon leads
- individual control of each amp's remote gain control
- interface to the CNX-P1900 DC-DC converter

My amp rack already has four completely custom Arduino boards networked together via RS-485, with CAT-5 cable. The new Arduino Due that just came out the perfect "hub" for them, as it sports an ARM processor with 54 digital I/O pins and four UARTs. This microprocessor board will handle a lot of the chores to leave my CarPC to handle the important stuff (playing music without skipping).