ABSTRACT

Pyrodigital Consultant's original purpose of Computer Control for Pyrotechnics was to simply be able to present Aerial Shells in precise synchronization to musical soundtracks for outdoor Fireworks Displays. The introduction and advancement of Computerized, or Automated, Firing Control has been meet with much skepticism and hostility.

Pyrodigital Consultants reviews it's 12 year history on the application of Modern Digital Electronics to the Art of Displaying Pyrotechnics leading up to it's current Software and Hardware "tools". Detail is presented on conceptual design of the Pyrodigital Phase III System which employs digital communications on a single cable to talk to a System Network of Firing Modules (slave units) from the main Controller (Field Controller).
Benefits and disadvantages of the Pyrodigital System compared to more traditional multi-conductor cable Systems are discussed.

One of the first lessons learned was that precision Computer Firing Control was of little use without a means to create the Firing Sequences. Pyrodigital's Choreography Software is discussed with specific Computer Screens and details presented. It was also learned that Computerized Choreography offers many advantages for designing Displays which are to be Fired with traditional electrical Firing Panels.

Specific Users and Displays are cited to give credibility. The paper clearly establishes that Computer Firing Control has matured enough and has been proven as viable technology providing a new tool and resource for advancing the Art of Displaying Pyrotechnics.

INTRODUCTION

Displaying Pyrotechnics can be differentiated as a separate task from the construction and Artistic merits of each individual Pyrotechnic device. Each Pyrotechnic device is an Art Form, and if only 1 device exists, then control over the Display of that one device is simple. When many Pyrotechnic Devices are to be combined into a Display, and additionally combined with other Art Forms, such as Music, then the task of the Master Artist, or Pyrotechnic Choreographer becomes difficult indeed.

Computer control of Pyrotechnics simply provides a powerful new "tool" allowing the user to compress hundreds or thousands of man hours of time into a single, perfect Performance. This time compression is the key element to the success of Film, TV, and Recorded Music. To successfully use the "tool" requires a new ap proach and organization. Intensive pre-planning is required. It is simply not possible to show up on location with some boxes of Pyrotechnic devices, randomly Fire a Display, and expect the results to compare to a well organized, pre-planned, and precisely Fired Performance. Computerized Firing requires more lead time and pre-planning, but that is the key element required to create "World Class" Pyrotechnic Performances in the Art of Displaying Pyrotechnics.

The beginnings of Pyrodigital - The Concept

The original founding concept of Pyrodigital Consultants was formed in 1980 by Ken Nixon in association with Mr. Bill Page and Mr. Dan Hyman of Primo Fireworks while listening to Fanfare for the Common Man by Aaron Copland. The obvious choreography for this musical score was to display Primo's custom large caliber chrysanthemum shells exactly on the kettle drum beats and the large musical crescendos. The problem then became how to Fire these aerial shells so that they would break exactly at the right moment in relationship to the musical score.

Brainstorming between Ken and Bob Nixon lead to the development of the Phase I System. The original Phase I Firing Console had 16 Firing circuits using DTMF (Dual Tone Modulated Frequency) technology borrowed from the Telecommunications Industry. On July 4th of 1982 Phase I successfully Fired 16 timed volleys of large caliber chrysanthemum shells in perfect synchronization to the Fanfare for the Common Man. The awesome impact of Fireworks and Music working together in harmony proved the concept and Pyrodigital Consultants was born.

METHOD

Phase I System Development

The Phase I System was immediately enlarged by Bob Nixon to 256 Firing circuits by adding a 16 circuit ground matrix operated by a second frequency shifted DTMF tone pair. Thus Phase I was

operated by 2 DTMF tone pairs each 1/10 of a second apart, the first selecting 1 of 16 grounds and the second tone Firing 1 of the 16, +12vdc hot circuits. DTMF tone pairs were recorded on 1 channel (track) of a 4 channel open reel tape recorder, while the music was in stereo on two adjacent channels.

The next major problem to become apparent was how to place the 256 possible DTMF tone pairs on an additional track of the tape recording in exactly the right timing relationship to the musical score. This was compounded by the fact that, for aerial shells, the shell must be Fired before, or ahead of, the desired musical "event" (in order for the aerial shell to achieve altitude in the sky and break synchronously with desired musical event). This rise time of the aerial shell became known as the "pre-fire delay", or "PFT" (Pre-Fire Time). Additional compounding the problem was the fact that the PFT varies by the type and caliber of the aerial shell. A 300mm Aerial Shell would have a much larger PFT than a 75mm shell, for example.

The solution was a custom built Computer based on the Motorola 6809 8 bit processor with assembly code firmware designed and built by Bob Nixon. Bob Nixon was the electronics genius with a wealth of experience and expertise, working as a consultant in the rich electronics environment of Silicon Valley (San Jose /Sunnyvale, California). Ken Nixon provided the financial resources, the pyrotechnics expertise, the mechanical designs, and the brainstorming motivation. Ken and Bob Nixon arrived at a satisfactory solution based on Time Code. The cornerstone, or foundation of the entire Pyrodigital Process relies on the use of Time Code.

Pyrodigital Time Code

Pyrodigital developed it's own Time Code based on commonly available FSK (
Frequency Shift Keying) modem type IC's (Integrated Circuits). Pyrodigital Time Code is unique, different, and much more powerful than traditional FSK Time Code. Pyrodigital Time Code consists of a unique and sequentially increasing time number every 1/10 of a second. This means that this unique Time Code number may be read instantly from any point without having to be reset to the beginning, as is the case with traditional FSK Time Code. Additionally Pyrodigital Time Code incorporates parity, or data correction, as part of the protocol. Thus PD (Pyrodigital) Time Code is an extremely robust, narrow bandwidth, data stream capable of being copied 20 or more times on low quality cassette tape machines without degradation. This has proved to be a very wise choice as PD Time Code is easily transmitted over normal phone lines, voice bandwidth radios, and long hard lines.

What Pyrodigital Time Code provides is an electronic timing link between the computer and the audio tape machine. In practice, Time Code is recorded, or striped, on an adjacent tape track of a multi-track tape recorder (minimum of 2 tracks). The final musical score for the Fireworks Display is recorded on a separate

track, or 2 tracks specifically for stereo music. When the music is played the Time Code is read by the computer. Thus the computer is now locked to the music via the Time Code and "time" becomes transparent to the user, thus freeing the user to concentrate only on the music.

In order to choreograph a Display with the Phase I computer, the user simply starts the tape, listens to the music, and depresses the space bar at the moment where an aerial shell is desired, based on the music. Depressing the space bar on the computer keyboard causes the Time Code number, or frame, to be captured into the computers memory. This time number is known as the "event time", or the time at which a specific pyrotechnic event is to occur. This is not necessarily the time when the pyrotechnic device has to be Fired. The PFT, or pre-fire time is an additional entry which, when subtracted from the event time, will
yield the Fire time.

One additional piece of information required by the Phase I Computer was the Firing Address. The Firing Address, or simply the Address, was the specific circuit on the Phase I Firing Console that would provide the +12vdc pulse to initiate the connected electric match.

With the combination of Event Times, PFT's, and the Firing Address, the Phase I Computer could now generate the DTMF tone pairs, which were recorded on the 4th track of the tape machine. In order to operate the Display, the tape is played with the music routed to loudspeakers, and/or a radio simulcast, and the DTMF pulses are sent to the Phase I Firing Console.

The Phase II System

The Phase II, or second generation System, was developed as a research platform in order to overcome the limitations of Phase I and determine what was actually needed for a marketable Firing System. Phase II incorporated an individual 24vdc capacitor discharge Firing circuit on each of it's 256 outputs and operated as a digital transmission System at 38 kBaud, capable of Firing 20,000 shots per second. Phase II also pioneered the modular concept, in that each group of 16 circuits became an individual "slave" unit connected to a main "splitter" or junction box by a
simple communications cable. This splitter was connected by another single long cable to the controlling computer. This allowed the Firing computer to be easily located from the pyrotechnics discharge site at any distance desired.

Phase II overcame the Phase I timing limitation because 2/10 of 1 second was no longer required in order to convey the DTMF tone pulse Firing instruction. Another tremendous benefit of Phase II was that the Firing instructions were no longer fixed on tape, but stored in the computers memory. This allowed for the inevitable last minute changes and revisions. Phase II was also

capable of interpolating between the 1/10's of 1 second Time Code resolution to extreme precision as well as being able to Fire simultaneously from multiple locations.

Phase II proved to be a very expensive System with capabilities far in excess of those required. Phase II, however, clearly demonstrated that Aerial Shells could be very precisely synchronized to the music as witnessed by large Commercial Displays at the Great America Theme Park, Santa Clara, California in 1984 and at Lake Tahoe for HARRAH'S Hotel Casino in 1985 (with Primo Fireworks).

The Phase III System

Phase III was the third generation of Pyrodigital (PD) Firing Systems. Phase III would again be a digital Firing System, taking advantage of the current digital technology. The Phase III criteria was to design a System at reasonable cost, with acceptable performance, that used standard of-the-shelf IBM PC / Compatible Computers for both Choreography and Firing.