XLAPRS New Hardware

Description of the new system...

The new hardware I am working on now (Mar 2003) is much more compact and low powered than my first try. Parts I'm using: The addition of the hard drive lets me devlop and make code changes on the system itself, much more convienent than building on a machine with a hard drive and then moving things to the actual computer that will run off compactflash.

With the more efficient power supply, low-power board/CPU, and switch to a dumb 4-port serial card (instead of the 8-port intelligent rocketport), I have power usage down to just over 1A at 12v -- 7 times less than before, and that includes all the pieces but the display. I'm very happy with the power consumption of the new hardware.


Got some major software work finished: So.. todo:


M12 and power distribution block are mounted now. From now on I'm just going to dump pictures into a section of my picture gallery.
Code status: I've written some code to fix the altitude output of the M12 GPS receiver; it only outputs GPS altitude so I had to calculate "geoidal separation" to get more useful MSL altitude. I also started work on getting the Matrix Orbital display code moved to Python; the serial port setup needed some hacking (the display wants software flow control but only in one direction, and not with standard XON/XOFF characters).


TNC mounted in box, M12 gps not mounted yet. Switched to flexible PCI riser (from Adex Electronics) also.


I'm now using a KISS TNC from W2FS. KISS mode is much easier to deal with from a softwre standpoint than all the KPC-3 terminal user interface gook. A couple evenings looking though the KISS and AX25 specs and I've got TX and RX working. As a bonus, the new TNC is about 1/3 the price of a KPC-3, uses less power, and is smaller!


I've taken some more detailed power measurements of all my new components. All measurements at 13.3-13.4vdc
MB + serial + HD in Linux, idle         0.847 A
F1500 idle, backlight off, no RX        0.230 A
GPS locked, no backlight                0.045 A
KPC-3                                   0.030 A

Total power during idle w/out display   1.12  A   ~  <15W

Surge power on computer startup (250us) 3.971 A 
The mini-box DC-DC supply was a big help in getting power consumption down -- my old 250W 12v ATX PS used almost an amp just to power its cooling fan and keep itself regulating.

Pics of new hardware in development

Have a basic case now. 17 x 10 x 3 inch aluminum box, mobo mounted with standoffs, hard drive hung by one side (need some foam rubber to cushion it). There's room under the HD for the OEM GPS board I want to get to replace the Garmin that's in here now. TNC is buried on the lower right under the GPS. I left room for a CF card adaptor on the left (over the HD ribbon cable). 2m radio is outside this box for RF sanity.

Hopefully there's enough air in here to keep temperatures sane while dissapating 15W of heat into the walls of the case (after I put the lid on)...

Side view 1

Side view 2

DMM, HD, computer, TNC, radio, etc.