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2004 DARPA Grand Challenge
A race of Autonomous Robot Vehicles across the desert

Communications For the Event



3rd St. R & D Production Services is a supplier of technical production services including Large-Scale Sound, Lighting, and Communications Systems for Concerts, Festivals and Special Events. 

3rd St. R & D’s Communications services distinguish themselves from those of radio rental houses by the depth of the system and infrastructure capabilities that can be brought to bear on large area, difficult coverage environments. 

The equipment and techniques used by 3rd St. R & D are identical to those used in permanent systems, except that equipment and infrastructure is modified for “portable” or transportable use.  Those modifications involve ruggedizing the electronics for transport and mechanical modifications to antennas to facilitate rapid set-up and tear-down. Site electronics are integrated into military-grade transportable communications shelters for transport and operation.

3rd St. R & D was contacted in April of 2003 about providing radio communications for an event called the DARPA Grand Challenge. 

really small darpa logo.jpg (4840 bytes) DARPA

The Defense Advanced Projects Agency is an agency of the United States Department of Defense, and is charged with identifying new technologies useful to the Armed Forces of The United States and initially developing those technologies.


DCG logo only really small.jpg (7760 bytes) The Grand Challenge

The DARPA Grand Challenge is an event of autonomous ground vehicles that was held on March 13, 2004. Congress and the Department of Defense view unmanned vehicle technology as a critical element of our future military capabilities. "The Grand Challenge is a bold effort to draw widespread attention to the technological issues associated with autonomous vehicles and to generate discontinuous breakthroughs in performance. The format and requirements of the event are specifically designed to target the companies and entrepreneurs that define grassroots American ingenuity so that innovative new approaches can be found." The Grand Challenge sent robotic vehicles over a course which began near Barstow, California and was to end near Las Vegas, Nevada; a distance of roughly 150 miles. 

Congress has mandated that the mundane overland transportation tasks of the military, such as supply convoys; shall be accomplished by autonomous vehicles before 2020. In order for these vehicle systems to be effective, they must be able to navigate and sense obstacles in their path without human intervention. In other words, once sent on a mission they are on their own. 

DARPA issued a challenge to non defense industry entities and individuals to develop and showcase these guidance technologies: 

"The challenge is to build a robotic vehicle that can successfully navigate a 150 mile course across the Mohave Desert in less than 10 hours without human intervention, with a $1,000,000 prize to the winner. The emphasis was to be placed on the guidance systems, rather than the vehicle itself. Challenge vehicles must autonomously traverse the challenge route without human interface or control of any kind. The vehicles must perform general route selection and navigation to follow the Challenge route. Vehicles must sense their environment to perceive terrain features, ground conditions, obstacles, and other Challenge vehicles. They must intelligently control their speed and direction so as to avoid or accommodate all of the above. And they must do these things quickly- overall speed will be the deciding factor and the time limit is designed to push vehicle speeds far beyond current technologies." 

A wide variety of entries answered the Challenge, ranging from teams sponsored by major universities to garage robot enthusiasts. Of over 100 entries, 25 were chosen to compete. Of those 25 accepted, 13 “Bots” satisfactorily completed a comprehensive QID (Qualification, Inspection, and Demonstration) event.


 The Need for Comprehensive Voice and Data Communications 

The prospect of a group of robot vehicles “loose in the desert” raises many concerns, such as safety, traffic and course control, environmental and ecological monitoring, and general race operations.  

Several hundred people were involved along the course for road closings and safety, as well as 25 biologists charged with tracking and wrangling several endangered species such as the Desert Tortoise and The Wild Burro. 

A large number of Command and Control personnel needed to access the radio system in the confined space of the Command and Operations Center in Primm, Nevada and the Situational Awareness Facility in Stoddard, California. 

Multiple repeater locations would be required, and Land Mobile Radio voice communications, Vehicle tracking data, computer networking, and telephone circuits had to be distributed along the 150 mile race course across the Mohave Desert. 

A VHF Aeronautical radio interface able to communicate with Air Assets (helicopters) over the entire race course would be required. 

For this discussion, the system will be broken down into subsystems:

*     The Command and Control System and equipment
*     The Microwave backbone to support LMR voice, Telco voice, and data downrange
*     Site Supervision and Power
*     The Repeater Network and the Terrain
*    The Land Mobile Radio Inventory and Allocations
*     The Human Interface
*     Data and Telco Network

Command and Control (Dispatch) 

Each “Bot” would have a chase vehicle (CV) following it in close physical proximity. Each CV was required to be in constant radio contact with a corresponding Judge at the Command and Operations Center (COC) Finish Line location in Primm, Nevada; as well as other observers at the Situational Awareness Facility (SAF) at the Stoddard, California starting line location. 

3rd St. R & D decided early on that the COC and SAF would be, to the maximum extent possible, “RF free zones”; with the minimum of radios transmitting from within the spaces due to the proximity of computers and other sensitive devices.

It would be necessary to provide each Judge with the ability to access multiple channels in whatever configuration the Judge deemed necessary, and permit easy channel switching and reconfiguration of those channels. The field of entries had been limited by DARPA to 25-30 vehicles. So, 25-30 hard comm positions for Judges would be provided at the Primm COC. 

A Race Director would oversee Operations at the Primm COC. The Director would be moving around the COC overseeing the Judges, and would have one of the few radios in the room on headset.  

Five comm positions at the Stoddard SAF would be required, and comm positions for Environmental monitoring and interface to Local, County, and State Agencies from both California and Nevada would also be required at Primm and Stoddard. 

The prospect of bridging 30 or more Tone Remote consoles together at the COC was daunting, considering the audio level jumps that would occur as users switched on and off the various channel busses, not to mention the table real estate that would be required for them. Then, bridging additional consoles from a location at the other end of the course was an additional level of unwanted complexity. 

However, since there would be distributed transmitters along the course, Tone remote control (TRC) would be used to control them so TRC capability would still be needed. 

vegalogo.jpg (9258 bytes) Enter Telex/Vega and VoIP

 The C6200 Console product from Telex Vega is a full-featured multi-channel dispatch console which is fully implemented with Digital Signal Processing (DSP). The native interconnect format for the C6200 is by way of Ethernet and Voice-Over-Internet-Protocol (VoIP). Analog Line Interface modules provide interconnection to analog radio systems.

Telex/Vega C-6200 Console

Telex Vega also offers a console emulation software application called C-Soft that runs on a PC. The PC interface can be custom configured to the requirements of the user, and the virtual control surface can be customized so that only the required controls and channels appear to a given user. 

With the Telex Vega System, an unlimited number of consoles and console emulation PC’s on a common network can operate as an integrated system. Any PC on the network running Windows XP or Windows 2000 and containing a sound card and headset can be used as a full-function dispatch console, or as a monitor point. In fact, the VoIP traffic can even be packaged and routed over the Internet, and with sufficient connection bandwidth the radio system traffic can be monitored at any point on the globe. 

The Telex/Vega system was a perfect fit for this project. 

Each Judge at the COC would have a PC to run the vehicle tracking software and would already be networked. The Judge could have the tracking software in the foreground for best visibility and the C-Soft application in the background. If channel changes or volume changes were required, the C-Soft window could be brought to the foreground, the changes made, and then returned to the background. C-Soft provides an interface via the serial port on the PC for an external PTT switch, which allows PTT operation of the application even if it is not in the foreground. 

Simple PC-type headsets eliminated the din of radio traffic in the COC. The left ear heard the select audio from the primary channel, and the right ear heard the unselect audio from the other channels. The individual user could mix his or her own ratios of unselected channels, and independently adjust the volume of select (long horizontal slider) and unselect audio (short horizontal slider). 


Actual Event C-Soft Panel over Map of Microwave Paths


In the COC, workstations were arranged around the perimeter of the area and in the center of the area.

The Primm COC in a quiet moment 

Two C6200 master consoles were used, one at Stoddard and one at Primm for 3rd St. R & D’s operators to monitor all radio traffic. The C6200 Console with Analog Interface modules at Primm acted as the primary interface between the VoIP stations and the tone remote inputs of the Motorola Digitac Voting Comparators at 3rd St. R & D’s communications trailer located adjacent to the COC at Primm.
VoIP traffic traveled the same network along with the tracking data for the Judges displays.
Networking Contractor CenGen provided guaranteed packet bandwidth on the LAN routers so that no delays or excess latency occurred with the remote C6200 console and C-Soft stations at the Stoddard SAF 150 miles away from the COC, even with near-full-motion MPEG video from Stoddard to the COC in Primm.


CenGen’s Master Router Bay in the NOC 

Cisco Systems Equipment: 

2621XM Multiservice Router

3725 Multiservice Access Router

AS5350 Universal Gateway

3550-12T Ethernet Switch

The Real-Time Vehicle Tracking Application was very processor-intensive. Desktop Support Contractor RSSI fine-tuned the computers so that processor time was guaranteed to the C-Soft application.

Network Microwave backbone 

In the initial planning stages of the communications system, a mixture of common-carrier fiberoptic and microwave T1 circuits was envisioned to interconnect the remote transmitter and receiver sites, with private short-haul microwave circuits to locations where common-carrier circuits could not be obtained. 

As the costing came in for the common-carrier circuits, it became clear that it would be more cost-effective to do a complete private microwave network.  

At a late date, DARPA also decided that the vehicle tracking system would have to become near-real time. The enhancements to the tracking system would require significant bandwidth downrange, and would increase common-carrier costs by an order of magnitude. Several methodologies would be used by network contractor CenGen to bring multiple data streams from downrange into Primm.

A robust and reliable microwave system would be required which would be capable of handling a mixture of traffic, including channelized T1, LAN, and routed RS232 data.

Adtran logo.bmp (5686 bytes) Wireless and Network Products

 Comprehensive planning discussions with ADTRAN’s excellent applications engineering department were essential to the successful deployment of this network. 

3rd St. R & D chose ADTRAN’s 4205 Quad T1 TRACER 5.8ghz product for the microwave backbone, as well as ADTRAN TSU600 units for radio control and telephone mux and demux.  

Since the microwave network would be temporary, there were limits to the size of the antennas that could be deployed for the network due to the requirement to use our temporary non-penetrating roof mountings (we call them "Lunar Rovers"). However, the hops between the radio system sites were as long as 42 miles. 

4 foot Andrew P4-57W antennas were chosen, and modified by 3rd St. R & D for use with our temporary roof mounting structures. The Andrew antennas have proven to be extraordinarily rugged. We use them in a way that they were not intended to be used. We haul them around, bang them up, and generally abuse them. Through all of this, their performance remains consistent and reliable. In fact, when we pulled them out of their transit frames to begin installing the system, one of the antennas for the 42 mile path had suffered a fairly substantial "ding" to the reflector surface several inches long.

In transit, four of them had bounced out of their frames and had pancaked on top of each other in the truck.

A couple of careful taps and the the dings came out and the path worked perfectly.

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Looks puny against the primary tower
Andrew P4-57W microwave antennas and Andrew/Decibel DB420Q Transmit antenna on top-of-the-world
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A Rover goes together 1, 2, 3 in about 90 minutes


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A Rover about to get attacked by an incoming storm

To keep path and transmission line losses within acceptable ranges, the ADTRAN TRACER radios were rack mounted in enclosures at the antennas. As can be seen from the photos above, these sites were “top of the world” sites which experienced strong winds in excess of 50-60mph, late winter snows, heavy spring rains, and thick fog. The paths held under all these adverse conditions.
At each end of the network, short hops of 5 and 8 miles respectively were needed from the first and last radio sites to the COC in Primm and the SAF in Stoddard. For these short paths, Andrew  P2-57W 2-foot antennas were chosen, and 60 foot feed line lengths of 3/8” heliax between the antennas and the terminus radios were possible with excellent margins.


       Stoddard SAF                                                   Primm Comm, NOC, COC (L-R)


The microwave sites, which were also UHF radio sites, were arranged as T-1 repeaters with TRACER radios connected back-to-back. 

At each site, the T-1’s were cabled down to temporary equipment shelters which contained the UHF radio equipment. In each shelter, ADTRAN TSU600 T-1 channel banks with drop and insert capability were used to drop the E&M circuits for the site and pass on the E&M circuits for sites downrange. Due to the excellent processing power of the ADTRAN equipment, no perceptible latency was introduced into the audio between the sites, even after passing through multiple channel banks and multiple drop and insert steps.

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Temporary Shelter and Roof Mounted Microwave and Radio Antennas

 More details and photos of shelter mounted systems

Site Supervision, Backup Power, and Facility Power 

CenGen provided a Cisco router at each site which connected to one of the T-1’s for tracking data and networking. CenGen also provided an APC 1.4 KVA UPS at each site to hold up the router, the tracking data equipment, the radio channel bank, and the microwave equipment. Tracking data from the vehicle tracking system provided by Omnitech Robotics was interfaced to the microwave network and routed up and downrange. Site condition telemetry and path health was derived from router link up/down status and packet errors, and the UPS status via Ethernet indicated utility power loss or presence. 

The Motorola repeaters were backed up with individual battery banks per repeater. 

Each remote site system was then further backed up with a portable diesel generator provided by Aggreko. If power was lost, the battery backup systems would hold up the site until a technician stationed at the site for the event could get the generator started and change over to it. 

A 150KW auto-start auto-transfer genset provided by Aggreko at the Primm COC provided backup power for the Command, Network, and Comm facilities. Battery backup and UPS’s would hold-up the critical systems during generator start-up and switchover. 

3rd St. R & D provided a 150KVA 480V to 120/208 transformer, 480V cabling and 120/208 distribution panel to interface with the primary 480V supply , the generator changeover switch, and feed the Command and Operations complex. 

Enough fuel was provided for all of the generators so that 24 hours of operation with all systems running could be achieved if all utility power between Primm, Nevada and Barstow, California was lost.

UHF Repeater Network and The Mohave Desert Terrain 

DARPA wanted the most comprehensive coverage of the course which was practical. 3rd St. R & D’s goal was to provide 90% coverage with handheld radios, and better than 95% coverage with mobile radios. The last few percentage points were judged to be outside the budget of the project. 

It went something like this: 

3rd St.: “Do you want to talk ‘anywhere’ on the course with portables, or do you want to talk ‘ANYWHERE on the course with portables?” 

DARPA: “What’s the difference in cost?” 

3rd St.: “About double.” 

DARPA: “ ‘anywhere’ is adequate.” 

“Coverage” was defined by 3rd St. R & D as full-quieting or near full-quieting performance within the 90 and 95% goals. The remaining isolated areas would be augmented with vehicular repeaters if required, or users would be instructed to find high-ground locations.  

DARPA had determined that 4 course-wide nets would be required, and that users would need to access any of the four nets at any point on the course. The terrain in the Mohave is very rugged with elevation variations along the route of from 800’ ASL to 5000’ ASL. Inquiries with public safety agencies with these areas in their jurisdictions indicated that radio coverage would be challenging. 

3rd St. R & D surveyed thirteen sites that were in the proximity of the several potential race routes in October of 2003 and tested six by placing temporary repeaters and driving the entire probable course. Testing with portables and mobiles permitted accurate coverage estimates to be developed. In ten days of testing, 3rd St. personnel racked up 2000 off-road miles performing the coverage tests. 

American Tower Corp. was of significant assistance in this regard, and seven ATC sites were selected. We really cannot say enough about the cooperation and help we got from Sam Drogin and Ron Mihares of ATC.

The site selections were made based on proximity to the course, the probable route of which was known by November of 2003. Subsequent evaluations and efforts to mitigate costs reduced the number of ATC sites needed to five. Of those, four would be UHF repeater and microwave sites, and one would be a microwave repeater site only. 

RF planning for the 5 sites began in November with path modeling for the microwave and coverage modeling for the UHF channels. When the final selection of the sites was completed, Doug Thompson of Cara Enterprises handled filing the complex STA for the UHF channels. 

Because of the proximity of the sites to each other (ranging from 22 - 42 miles apart) and the elevations of the sites (as much as 6000 ft ASL), it was certain that if all the radio sites were on identical repeater talk-out frequencies there would be significant co-channel interference. In fact, from a couple of the sites, ALL the sites could be heard.

Route Map of the Microwave System with UHF Radio Sites


However, the proximity of the sites was ideal for implementation of a multi-channel, multi-site voting system. A channel scheme was developed which allowed all the sites to receive on the same set of four receive frequencies, but allocated transmit frequencies in even/odd sets at alternating sites. This allowed 80 miles between sites that used  identical transmit frequencies. The harsh terrain and mountains of the Mohave would provide sufficient isolation between sites using the same transmit channels in all but a few locations.

Actual Elevation Profile of Repeater Sites Across the Mohave

Motorola repeaters, operating in voted repeater configuration with integral 2175hz voting encoders and standalone revert features, were chosen for the sites. The repeaters were controlled by a central bay of Motorola Digitac voting comparators in Primm, Nevada. As previously mentioned, all receiver audio from the repeaters was routed to Primm, Nevada via the microwave network for receiver voting, and transmit tone control was routed back to each site. The Motorola ICR (In cabinet repeat) repeater feature provided a fail-safe for local repeater operation to continue if the microwave network experienced an outage. If a gap opened in the system connectivity, personnel stationed at each site with high-power mobiles would have the capability to relay message traffic to the next repeater in the chain that had connectivity, until that connectivity could be restored. Due to the reliability of the network, that layer of backup was never used.

The Motorola Digitac comparators have extensive audio input and output flexibility and readily accommodated the complex audio paths required to interconnect the system and the dispatch console chain; and can accommodate 8 receive site inputs per system channel. 

The Digitacs are part of an existing system owned by 3rd St. R & D and used for other large events over large geographical areas. The DARPA system was a build-out of the existing system, going from two repeater sites to four repeater sites, with one additional receive-only site. 

Four course-wide channels were required to support event operations over the entire length of the course, and six simplex local channels would be used at areas where concentrated communications were to take place, such as road closings and crossings. Of those six local channels, five were allocated for specific purposes, and the sixth was allocated for use either as an independent channel or it could be used to relay through vehicular repeaters in 3rd St. R & D vehicles.

Build-Out, Installation and Turn-on

Build-out of the system began in November of 2003 and was largely completed in time to load and leave for the desert on January 6, 2004. Installation in the desert began on January 10, 2004 and the system turned on January 18, 2004; an elapsed time of 12 days from leaving Missouri until the system was installed and turned on.

The site equipment was contained in three portable communications shelters and one 4WD truck and all traveled on a flat-bed semi-trailer.  

Shelters and Truck Site Loaded for the return trip

Three sites could be reached “easily” by hauling shelters up to them in pickups, but one site, although only 5 miles air distance away from the Primm COC, was a 44 mile round trip much of which required 4 wheel drive
For that site, the truck mounted equipment was used.

The truck for that site has mountings for the microwave antennas and an integral crank-up tower for the UHF antenna system.

Since the site was at 4000' ASL, the tower did not need to be cranked up.

.Testing and Tweaking

During February, several test excercises were run, and the system was tweaked and fine-tuned for best performance. Interesting and unanticipated effects were noted after tweaking was complete.

We knew that the voting system would be an important element to the system, but we really thought that it would merely be a means to utilize receivers at a number of locations. We thought that if any mobile was within 15 or 20 miles of a receiver that it would be sensed by that nearest receiver and that would be that.

Due to the topography of the Mohave and the shadows of the mountains, and the fact that the UHF signals would duct long distances through the mountains; there were times when the active receiver would be at a great distance from the transmitting mobile. There were many locations where a nearby site would be totally shadowed, but a site 60 or 80 miles away had the mobile full-quieting. The voting system was essential for successful operation.

We had mostly used the voting system with portables in the past, not so much with mobiles. The additional power (110 watts vs. 4 watts) meant that the mobiles were able to activate very distant receivers for clear coverage where portables might not have.

We also became aware that the portables have very different audio quality than the mobiles. Motorola portables typically have very smooth audio response. The Spectra, GM300, and Maxtrac mobiles on the other hand, have audio response tailoring in the circuits of their palm microphones which give them some additional boost in the upper end of the voice range for enhanced intelligibility. That boost in the high frequencies caused the comparators to evaluate the audio as being noisy under some full-quieting conditions especially with some user voice characteristics. We developed an improved method of setting reference levels to eliminate those effects.

Interestingly, mobiles which were equipped with David Clark Headsets, which have VERY smooth microphone elements without additional response tailoring, did not cause these effects even with "hostile" voice characteristics.



Land Mobile Radio Inventory Allocations


Mobile and Portable Units for Control Vehicles 

For the Control vehicles (CV’s), 3rd St. R & D provided three radio units per vehicle:
1 - 110W UHF Motorola Spectra Mobile with A7 head
1 - 25 W UHF Motorola Radius GM300 mobile
1 - 4-watt Motorola UHF Portable 

25 Standard CV’s and 5 “Super CV’s” were equipped with this unit complement. 

Standard CV’s were each assigned a specific ‘Bot to control. A 900 MHz RF E-Stop remote control link provided by Omnitech Robotics connected each CV to its respective ‘Bot. If the ‘Bot left the course or appeared to be exhibiting dangerous behavior, the CV could E-Stop the ‘Bot either in a pause mode or in a shut-down-and-disable mode.  

The “Super CV’s”  had master control E-Stop systems in them which could take over for any CV which experienced mechanical difficulties. The Super CV’s were stationed along the course so that they could quickly enter the course, catch up with the ‘Bot and CV and take over for the compromised CV. 

The Spectra was used as the primary course-wide radio on the primary nets. The alpha-numeric display was essential in the bright sunlight of the vehicle cab and was readable by the radio operator even under the rough ride conditions of the course. 

Spectral purity of the mobile radios, especially the high-power Spectras, was essential since the first harmonic of the UHF frequencies could have had a very deleterious effect on the critical 900 MHz E-Stop systems. The antenna systems for the UHF radios and the 900 MHz radios were only about 18” apart on the vehicle. No ill effects were observed in testing and in use. 

The GM300 radio was assigned primarily to monitor the course-wide Safety channel, and to provide a backup in the event that a Spectra or a portable had a failure during the event. 

The portable was used for local comm between nearby Control Vehicles to coordinate passing, and for local communications with road crossing crews as the vehicles approached them as well as with observation helicopters overhead. 

The right-seat Judge controlled the local portable and the Safety Net radio, and the backseater operated the Spectra for contact with the COC Judges and Race Director.  

Portable (Handheld) Unit Allocations 

Along the course, 55 portables were allocated to road crossings and at locations where the ‘Bots were to travel public roads. 20 Monitor Point observers watched critical locations where the ‘Bots would come into close physical proximity to power lines or other utility infrastructure. 10 Master Transmitter operators could take over control of a ‘Bot from a CV if dust or distance obscured the CV’s view. 

Race officials at the Start and Finish lines, COC and SAF were issued 30 portables and headsets for local coordination of those activities. 

Five Air Asset helicopters, in addition to their aeronautical radios, were issued Motorola Portables with SetCom double-muff high noise level Series 7 headsets so that they could communicate with the CV’s below them. 

An aeronautical radio with tone remote interface was placed at the mid-course radio site at an elevation of 4000’ AGL. That Aeronautical radio could be accessed by any Comm position to directly communicate with the helicopters from either the COC in Primm or the SAF in Stoddard. 

The biology staff, charged with monitoring and protecting the Desert Tortoises, was issued 25 portables. The Tortoises exhibited an uncanny knack for being discovered in the few locations along the course where portable coverage was below specification, so key biology lead personnel were issued GM300 mobiles for their vehicles. 

All told, 246 portable radios were issued to users along the 150 mile course, along with 37 GM300 mobiles and 35 Spectra Mobiles. 

All the equipment performed beyond expectations and the communications system and ancillary systems were judged to be “rock solid” by DARPA personnel.


The Human Interface 

Minimal training time was available for all the various people who would use the system. Because of CenGen’s excellent work, computer users were basically unaware of the length and breadth of the network. 

The communicators, both mobile and in the COC/SAF had widely varying levels of experience with radio systems and operation, ranging from none to significant experience with tactical battlefield communications. Training for the communicators (judges) who were to use the C-Soft application was very time-limited, and except for two short sessions to acquaint the users with the basic on-screen controls, their only real training was hands-on during two practice runs. 

Because the C-Soft screen can be designed for the specific application, non-essential controls were deleted from the screen interface and it was reduced to the bare minimum. The users were able to quickly learn and adapt to the interface and use it effectively. 

The behavior of a voting system took a little time to get used to, as the mobile users had to be made aware of the need to “push the button, take a breath, then talk” to give the system time to make a receiver decision; and to give the transmitter chain time to come up on a console push to talk. 

It was clear that most users were conditioned to military point-to-point simplex PTT behavior of walkies in close proximity, rather than the setup times involved in repeater systems with tone squelch and keying tone sequences. 

However, the users quickly adapted to the need for good technique and it ceased to be a problem. Keyup and vote setup was still much quicker than a trunked system. 

As previously mentioned, it was necessary to reduce the number of radios in the COC and SAF locations to either none, or to only units with headsets due to the audio latency introduced by the VoIP systems. It is in the nature of VoIP for there to be some minor audio latency, generally on the order of 300ms or so. This latency was not a factor to any user not actually in the COC or SAF, but could be a source of confusion to a radio user in the COC, or to a communicator who was hearing his voice come out of a radio 300ms late. 

Since the entire repeater chain was analog and was not distributed with VoIP, there was no latency involved in mobile-to-mobile or mobile-to-portable transmissions. 

Radio traffic was at times very, very dense and contentious; and the system spent significant amounts of time in nearly constant multi-channel keyup handling the message traffic. 


Computer Network and Telco 

All outside network connections such as Dedicated Internet Access, Data circuits to various points in the US, and landline telephone service was landed in the Network Operations Center (NOC) in Primm. Telephone and data connectivity in Stoddard would be difficult at best due to the remote location. The NOC was the termination for 8 T-1’s and two ISDN circuits.  

Of those landline T1’s, #1 was 24 Telco dialtone circuits, #2 was a Class C Dedicated Internet Access circuit, and the remainder were involved with the various incoming data streams for tracking from Verizon AirCard, Globalstar, Inmarsat, and other sources. 

The Telco T-1 was wired to 3rd St. R & D’s temporary facility next to the NOC where it was demuxed. Using an ADTRAN TSU600 channel bank with drop and insert interface and FXS analog loop start interfaces, sixteen lines were dropped at the COC, four at the NOC, and the remaining four were piped down to Stoddard over the microwave network to another TSU600 channel bank with FXS interfaces. 

DARPA Contractor CenGen  Networking, Inc. handled the complex data circuits and routing equipment for tracking and computer networking, and provided integration for the several vehicle tracking methods into a single data stream. That data stream was routed onto the local LAN in Primm along with the VoIP packet stream for the Telex/Vega dispatch equipment. A near-full-motion video stream from the Stoddard Starting Line as well as a video stream from the Fontana, California QID location via the Internet, were also routed onto the network. 

CenGen then bridged the Primm and Stoddard LAN’s over 3rd St. R & D’s microwave network. Of the four T1’s available on the microwave network, #1 was allocated to 24 E&M circuits for radio system interconnect, #2 was allocated to Telco transport from Primm to Stoddard, #3 was allocated to an Ethernet Bridge between Primm and Stoddard, and #4 was allocated for Tracking Data.

The combined Radio, Microwave, and Data Communications system worked flawlessly together. 

Tear-Down of the systems began the day after the event on March 14, 2004 and was completed and the last truck left on March 18, 2004  --  4 days from fully operational to totally clear of the area.



3rd St. R & D's unique experiences with this project have given us an even greater range of insights into techniques and methods which have application in not only transportable, temporary systems; but also in fixed systems which are required to cover large areas.

Our systems have application not only in special event communications, but also in disaster restoration and other mission critical temporary situations.

Our existing experience base with large systems is now vastly expanded to include a variety of networking technologies and equipment.

Consultation and installation services involving voting systems, Vega Dispatch Products, and Adtran Wireless and Networking products are available.

These technologies and techniques can be easily and cost-effectively combined with or added to existing fixed systems to improve their performance and coverage.


Greg Carttar
3rd St, R & D Production Services
109 Shawn Road
Kirbyville, MO  65679


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The Vendors:

Motorola - What else can you say?
Vega Signaling - C6200 VoIP Dispatch products, C-Soft PC Console Emulation Application
Adtran - Simply the best Network Access Products and Tech Support
David Clark - Headsets
Futuretest - Rapid ( ! ) prototyping and production runs of custom circuits
Talley Communications
AfComm Supply
Andrew Corporation - Antennas and Site Products

People we've met on this project that are just the best:

Cengen - Certified Cisco Networking Consultants
RSIS - System Integrators / Support
Mindtel - Dr. Dave Warner
Omnitech Robotics
Aggreko - Generator Rentals

Special thanks to:

Phil Angell, Platronics Communications
Dave Firis, Firis Communications
Dave Bishop, Dave's 2-Way
Len Werman, Utah Communications
Doug Thompson, Cara Enterprises
Dave Dunford, Lenexa, Ks PD Communications
Bob Gogley, Bill Locke, Jerry White, Ernie Garcia, Earl Oya - SBC Communications/PacBell Radio Operations
Wayne Wakita - Sprint Communications

The WHOLE staff at Primm Valley Resorts, Primm, Nevada

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