About Ron Burkey
PBS-400 and PBS-250 Passenger-Briefing
At a Glance
I provided the complete hardware and firmware designs for these
Heads Up Technologies avionics products in 1991. Among the things
I provided were:
Schematic-diagrams and layouts for 7 circuit boards (plus two alternate
that never went into production).
Firmware and MS-DOS-based support software: a large but unknown
quantity of C and Intel-8051 assembly-language code.
Documentation: 40 pages of documentation for specification,
software-certification, and internal engineering purposes, plus large but
quantities for hardware and software documentation purposes.
These products were intended to be improved versions of the
earlier Heads Up Cabin Briefer product. Among
these improvements were the following:
Audio-playback quality was to be improved, and maintenance of the audio
Royalties were to be reduced by replacing the speech-compression algorithm
used with a proprietary algorithm.
The user-interface was to be made more friendly by adding an LED-based
The capacity of the unit was to be increased (i.e., more minutes of audio
playback were to be provided).
The unit was to be field-reprogrammable, rather than configurable only
at the factory.
Multiple languages were to be supported, so that the unit could contain
briefings in several languages, with the actual languages played back being
selected only at flight time.
Accomplishing these various objectives was not merely a matter of
electrical design and of coding, because several significant technical
hurdles had to be overcome that affected not only these products, but also
many other product designs for years to come. In fact, the hardware,
firmware, and support software are not repackaged Heads Up Cabin Briefer
items, but are complete replacements. Here
are some of these technical highlights:
I invented a completely new audio-compression algorithm. This turned
out to be a lossless 8-bit audio-compression, in which raw 8-bit samples
were typically reduced to about 5 bits. This algorithm was used at
Heads Up for many products for many years, and at this writing (5/2001)
is still used in the majority of products delivered by Heads Up (though
not in new designs).
These were the first designs at Heads Up in which multiple processors were
used within a single unit. Some versions had 3 processors, though
most delivered units had just 2 processors. (There were several iterations
of the design, based on differing memory technologies.) Communication
among processors took place by means of protocols I created.
Field-reprogrammability of the units was accomplished by connecting the
units to PCs through standard printer ports. This meant that additional
protocols had to be created for this communications channel, and that PC
software suitable for use by customers (rather than merely suitable for
use by trained Heads Up personnel) had to be created.
While I don't claim to be equally satisfied with the solutions to
each of these problems, a significant amount of solid work was certainly
accomplished. The field-reprogrammability was the most unsatisfactory
point, as it proved vulnerable to incompatible configurations of the numerous
PCs used by the customers and to fragility of the protocol. Nor was
it very user-friendly. On the other hand, though, the field-reprogramming
software evolved into a general-purpose remote-diagnostic program that
(in spite of the kinds of flaws mentioned) provided important services
in quite a few additional products, and within Heads Up is runs continuously
on several computers. Here's a screen-shot of a recent version of
the diagnostics program:
This page was last modified by RSB on 04/20/02.