A TDMA BROADCAST SATELLITE / GROUND ARCHITECTURE FOR THE AERONAUTICAL TELECOMMUNICATIONS NETWORK

Mohammed A. Shamma, Rajesh S. Raghavan Analex Corporation, Cleveland, OH 44142 Contract NAS3-00145, NASA Glenn Research Center

Abstract: An initial evaluation of a TDMA research stage [ 11. Several communication satellite broadcast architecture with an links, technologies, and architectures were integrated ground network is proposed in considered which differ in complexity, cost, this study as one option for the Aeronautical and the time frame for its implementation. Telecommunications Network (ATN). The Here we are proposing an architecture based architecture proposed consists of a ground on the following objectives: based network that is dedicated to the - Cost: A system that takes into reception and transmissions of Automatic account the initial cost of Dependent Surveillance Broadcast (ADS-B) implementation. Considering the messages from Mode-S or UAT type fact that such architectures are not systems, along with tracks from primary and mass produced, the initial cost secondary surveillance radars. Additionally, will likely determine the expected the ground network could contain VHF final costs. Digital Link Mode 2, 3 or 4 transceivers for - New but tested technologies: In this the reception and transmissions of we mean a system that relies on Controller-Pilot Data Link Communications technologies that are new but (CPDLC) messages and for voice. The already tested as oppose to being second part of the ATN network consists of in the initial research stage. Also a broadcast satellite based system that is minimum use of what is defined mainly dedicated for the transmission of as older technologies is assumed. surveillance data as well as En-route Flight - Enough Room for Technology Information Service Broadcast (FIS-B) to all growth: while the cost and the aircraft. The system proposed integrates technologies in existence or near those two network to provide a nation wide term existence determines the comprehensive service utilizing near term or main architecture, it is important existing technologies and hence keeping the to leave room for other not yet economic factor in prospective. The next mature technologies to be few sections include a background implemented within the introduction, the ground subnetwork, the architecture at hand without satellite subnetwork, modeling and significant changes, Nonetheless simulations, and conclusion and where there may significant recommendations. changes required, they are noted.

1. Introduction The ATN proposed architecture is illustrated in Figure 1. It is divided into three parts. The Aeronautical Telecommunication l-The ground sub-Network which Network (ATN) is comprised of many consists of (but is not limited) two entities which are under development or at a major sub components: This is a preprint or reprint of a paper intended for presentation at a conference. Because changes may be made before formal publication, this is made available with the understanding that it will not be cited or reproduced without the permission of the author. a- Surveillance System: ADS-B The next two sections outlines some of (mode S and UAT) ground the details of the ATN parts discussed above transceivers. Primary and with the ground links and the airplane nodes secondary surveillance mentioned within. While the key element of radars (mode S and Air Traffic this design comprises the integration of Control Radar Beacon System satellites with ground based networks, it is (ATCRBS)). also the architecture which is seen to meet b- CPDLC and voice best all the objectives outlined in the communications network: beginning, cost, new technology, and room This consists of VDL 2, 3, or for improvement. communication transmitters 4 In summary, the architecture works as and receivers (depending on follows; aircraft equipped with ADS-B which link will be chosen). (UAT or Mode S) transceivers transmit their All VDL links will be in the ADS-B message to ground stations that are VHF band and hence will not located approximately 150 miles apart effect the surveillance (enough distance to receive from any systems design. altitude). At the same time, aircraft which 2- The satellite sub-Network which are not equipped with ADS-B transceivers consists of two major parts: will be detected by the primary or secondary surveillance radars. The ADS-B ground Satellite ground stations used a- receivers, and the radar stations will all be to transmit TIS-B and FIS-B connected via ground links (such as T1 or messages collected from all fiber, or possibly microwave, or a the ADS-B and radar ground combination) to the satellite "Pround station. transceivers. Satellite ground stations are presumed to be b- The satellite itself used to located in strategic locations such as at the relay the satellite ground ground control centers of each of the major stations TIS-B and FIS-B airspace sectors. Data collected will be messages to all the aircraft. filtered to remove any redundant messages 3- Ground links used to connect all received by more than one system (i.e. one the surveillance, VDL, and aircraft message seen by more than one ground satellite stations to each ADS-B receiver as well as with radar) and a other or to main stations. TIS-B message will be constructed per each 4- The airplane transceivers, which to transmit to the satellite. The satellite consists of VDL, ADS-B, and ground stations will access the satellite via a Satellite equipment. TDMA accessing scheme hence at each satellite ground station the filtered data will be queued and a burst will be transmitted within the corresponding time slots. The satellite will receive those messages and simply broadcast it down to the aircraft which will listen to the slots of interest based on the region of interest. At the same time while this is happening, CPDLC data and voice will be transmitted and received via ground VDL links with no satellite usage. Also, FIS-B messages will be created and sent along with TIS-B messages from each of the ground stations to be Figure 1: ATN major components broadcast to all the aircraft. The systems can have redundancies in the form of at a slower rate. Secondary surveillance redundant satellite transponders, redundant radars are described further in [2]. ground stations or reliance on radar vs. Supplementing the radar systems are ADS-B, redundant ground links via other ADS-B ground stations which listen to means if necessary. The details of those ADS-B transmissions from aircraft sent via redundancies were not investigated for this the Mode S and Universal Access study Transceiver (UAT) data links. Commercial aircraft, and other high-performance jet aircraft optionally broadcast their position, 2. The Ground Network velocity, and intent information using Mode S, while most general aviation aircraft optionally use UAT. The minimum aviation The ground network, shown in Figure system performance standards for ADS-B 2, consists of a network of ground-based are described in [3], and descriptions of the radar sites, as well as stations listening to Mode S and UAT data links as used in ADS-B transmissions from nearby aircraft. ADS-B can be found in [4]and [5]. The ground-based ADS-B listening stations, and the primary, enroute, and secondary surveillance radar sites feed their information to TIS-B ground stations, which process the incoming data to remove redundant information. The TIS-B ground stations then uplink filtered data to aircraft via a satellite network to provide a complete situational awareness picture to aircraft equipped to receive TIS-B information. Redundant data needs to be removed ...... ~. ' ...... 'G \ for the following reasons: 'G "--'- d \- 1) ADS-B transmissions from the same aircraft may be heard by Figure 2: Surveillance Ground more than one listening station Subnetwork in the ground-based network. However, that information should be relayed via satellite The ground-based radars are of three only once. types: primary surveillance radars, located at major airports, higher power en-route Even when an aircraft radars, and secondary surveillance radars co- broadcasts ADS data, it is located with the first two types, which probably being tracked by interrogate transponders on board aircraft in ground-based radars as well the vicinity. The secondary surveillance (except in remote areas.) The radars are of two types: Air Traffic Control satellite ground stations should Radar Beacon System (ATCRBS) and Mode only uplink whichever data is Select (Mode S.) The ATCRBS radars, in collected that is of a higher turn, are divided into two further types: quality. older radars interrogating aircraft at a higher Each listening station in the ground rate using a sliding window, and newer network generates ADS-B packets at a monopulse radars which interrogate aircraft specified rate for the purposes of the simulation, as opposed to actually listening to many aircraft. This is done in order to receiving aircraft. The speed up the simulation. The ADS-B traffic interference environment for is generated at the intervals specified for Mode S ADS-B consists of individual aircraft in RTCA DO-260A, the replies to Mode S and ATCRBS 1090 MHz Extended Squitter MOPS, ground radars which are sent on divided by a mean number of aircraft per the same frequency (1090 ground station, defined at simulation time. MHz). The interference environment for the UAT data The packets transmitted are 112 bit link consists of military JTIDS Mode S packets, again chosen for transmissions and interference convenience. ADS-B and TIS-B from TACANDME information relayed to the satellite ground navigational aids. stations in a real system are likely to be Mode S Extended Squitters. Although The ground network is structured in a different packet formats may be used within hierarchical fashion. ADS-B listening the SATCOM network, in the current stations and primary, enroute, and experiment the Mode S format was retained secondary surveillance radar sites, feed because in a SATCOM system, each ground their information to regional processing station will still need to relay the 56 bit centers via either T1 or optical links. ADS-B payload, as well as the 24 bit ICAO The regional centers in turn, forward the address. Using a 112 bit packet allows for four bytes of header information, at least collected information to one or more some of which will definitely be present in satellite uplink ground stations. Multiple any SATCOM link. satellite uplinks may be used to combat the effects of local weather disturbances The primary reasons for the existence on the uplink transmissions. The of the TIS-B satellite network can be described as follows: downlink to aircraft will not be as affected by weather since most aircraft 1) Not all aircraft are equipped using the service will be flying above the with ADS-B, and even aircraft cloud layer. that are equipped may be using either Mode S, or UAT, but not both. Aircraft sending ADS-B information, will receive ADS 3. The Satellite Network information broadcast over the same data link (Mode S or Figure 3 shows an OPNET [6] network UAT) that the aircraft use to layout which also serves to illustrate the transmit their own ADS-B data. architecture of the satellite sub-Network. An external source (the satellite The figure is shown for the continental network) is needed to provide United States (CONUS) but can be easily data about aircraft using the generalized to other areas of the globe. The other data link, or about aircraft satellite ground stations are assumed which are not transmitting collocated (not required but preferably for ADS-B information at all. The economical reasons) with the regional last group of aircraft are only control centers hence there are 20 within the seen by ground-based radar. CONUS. In addition to the 20 stations we 2) The range of ADS-B is limited show a central processing center that is by the transmitter power of the connected to all stations which can be use sending aircraft, and by the for multi purposes including redundancy interference environment management in case of weather, malfunction present between sending and or upgrade reasons, global data manipulations, and other. The Geostationary satellite is located at (W101 degrees) to Jplink Frequency (GHz) 29.750 serve those stations. Again the satellite %miink Frequency (GHz) 19.95 location is chosen to serve the CONUS and L GSO SatelliteTansponder Parameters surrounding area but can be used for most of Jplink qmder saturation flux density (dBW/mh2) -96 the North and South American continents Xponder saturaticm ElRP (dBW) 54 with more satellites needed to fill the globe Uplink receive CYT (dWK) 13.9 if necessary. Uplink receive noise temp (K) 575.44 Uplink receive gain (dBi) 41.50000047 11 telliie Aiiitude (km) 35786

TC Hub Station Parameters tenna diameter (m) 2.4 mit gain (dBi) 55.26205892

..’ ~Wpower(dBW) 17(50.12watts) mit ElRP (dBW) 72.26205892 ew gain (d8i) 51.79117752 ystem Noise Temp (d6-K) 26.67 (464.52 K) ew CYT (dm 25.12117752 EElevation angle to satellite (deg) 40 Aircratt Terminal Parameters ew gain (dB) 37 ystem Noise Temp (dEK) 25 (316.23 K) EWW(dB/K) 12

Figure 3: CONUS Satellite sub-Network 1OOOOOOO (note that each node above corresponds to a sector with a satellite earth station and ADS-B ground stations as shown by Figure 2. The satellite node is not shown).

As described in the last section and in the 40 introduction, each of the ground stations will 13.30864957 43.34567522 be transmitting a burst of messages at a 37780.30419 TDMA rate of 0.01 second time slots with a -213.4628304 0.005 guard band. Hence for 20 stations we -0.461666838 are able to receive a TIS-B or a FIS-B faster -14.56591541 than the minimum required rate of 1 per -1 85.2728554 second. Note the time slots can be increased five fold and still meet that requirement. 37780.30419 Again if more ground stations are added to -209.991949 fill other regions then correspondingly -0.447838163 smaller time slots will have to be used. -1 316.23 K Other types of accessing schemes can be 79.41685937 considered, none the less TDMA is widely used and hence from a implementation point 76.41433558 it is an acceptable choice. Also, since for 7.414335582 this architecture, we are not requiring EWNo (dB) lb6;QPSK; r=1/2 conv code 4.5 uplinks from the airplanes to ground (or no Return channels), as well as the broadcast Table 1: Satellite System Parameters per feature, the need for more capacity via other Transponder (Final results of link margin accessing schemes is not the main issue. In shown obtained from more detailed models r71) [7] more results are shown for trade off The data traffic modeled in this between TDMA and CDMA accessing. In simulation was only ADS-B messages summary the choice of TDMA for this purely for matter of convenience. The data architecture is appropriate because we have traffic could conceivably include TIS-B fixed ground links that can be synchronized messages generated from radar, as well as with less effort, as well as the fact that we FIS-B information as well, provided that can use the full power settings. The links additional resources are allocated (i.e. higher proposed are not rigid at this stage but are bandwidth transponders, or additional recommended to be in the Ka band mainly transponders on the satellite and ground to reduce the antenna sizes to be mounted on ends). Other advantages of Ka the aircraft [SI. Figure 4 is a plot of two of the ground band such as higher bandwidth availability stations. The top plot shows the TDMA are not applicable or critical since mobile burst transmission rate for one ground and broadcast FCC requirements limits the station from Figure 3 (and Figure 2). available bandwidth to 500 Mhz regardless. Similarly, the bottom plot shows the TDMA The C band, Ku band, and Ka band all have transmission rate for another ground station. the same allocations, hence the main thrust The other stations are not shown, but the will be antenna size and available spectrum profiles will look similar taking different at time of implementation. None the less, if time slots per station. The time between the antenna sizes and cost of mounting each burst of TDMA transmissions is seen issues are not taken into account, then in as equal to the total number of stations reality the lower bands (Le. C band) will be minus 1 (or 20-1=19) multiplied by each better with respect to rain, and weather station time slot (in this case 0.01 sec). attenuation. Table 1 below shows some of the parameters assumed for the satellite system per an assumed 27 Mhz transponder.

4. Modeling and Simulations

The previous two sections summarized the ground and satellite networks respectively and Figures 2 and 3 were obtained from the architecture built using the simulation package OPNET [6]. The aircrafts were simulated by transmitting ADS-B message sets directly from the ADS- B ground stations (shown in Figure 2) at the mean rate of 10 ADS-B sets (corresponding to 10 aircraft per ground station per Figure 4: Plots a and b, TDMA ARTCC) with a standard deviation of transmissions from satellite ground (0.4*mean rate) using a uniform stations (only two station shown of the 20) distribution. The reason for not including the aircraft as separate mobile nodes was mainly to speed up simulation time and not Also, it is worth noting that during one due to inability to do so as per the TDMA time slot, the burst rate is at description in Section 2. The one mobile maximum setting until all the packets in the node in Figure 3 was included for testing ground station queue are transmitted. If the purposes to check reception quality at higher queue is emptied before the end of one time aircraft speeds. slot then the transmitter will stay idle unless it receives any packets within that time in typical satellite transponder with enough which case it will transmit those directly (at additional room for higher data rates that are least based on the present design). needed for transmission of other than TIS-B messages such as FIS-B, control and paging The satellite on the other hand is receiving channels, and others. Needless to say if from all of the ground stations and hence its higher data rate are needed then the use of data rate profile has no gaps (assuming all higher bandwidth satellite transponders is an stations are active) and that is shown by the option, or the use of more than one is top plot of Figure 5. Since the satellite is a another more costly option. Other bent pipe, it simply re-transmits all the data performance parameters were observed from it receives at the downlink frequency where the simulation that are not shown here it will be intercepted by the receiving mobile included queue sizes and number of packets (or fixed) nodes. The second plot of Figure received, power levels, and several more. 5 shows the received S/N at the satellite node. It is worth noting that this value is large compared to that shown in Table 1 of the link budget analyses due mainly to not including rain attenuation (14.56 db) (Le. clear sky condition) along with polarization and atmospheric attenuation effects (1 db and 0.5 db respectively) in the channel model of the simulation used. Note that if we subtract those values from the S/N value seen in plot, we arrive at the values shown in Table 1 for the Uplink taking into account the 20 Mhz of bandwidth assumed to convert to S/No in db-hz. In numerical terms (30- 14.4-1 -0.5)+ 1OLOG(20e6)=87.1 which is very close to the values found in Table 1 for the S/No of 85.3. The reason Figure 5: Plots a and b, TDMA receptions for the 1.8 db difference comes from a at satellite (first Plot shows bits/sec variation in the antenna gains (amounting to throughput, second plot show S/N in db) almost 0.7 db) and small path distance differences due to the locations of the stations and the satellite. Hence, we had On the downlink side, the signal was kept that in mind as we arrived at the very observed from a moving mobile node small BER using the standard BER tables (airplane in flight), and at the fixed earth for QPSK in OPNET (not shown). Even if stations. With clear sky conditions the we included those additional terms we reception between the aircraft and the earth would still have negligible BER that fixed nodes differs due to the different gains matches with the link budget results of of antennas, and the path distance (hence Table 1. path loss) all stated in Table 1. The plots of The data rate from each TDMA satellite Figure 6 shows the received signal data rate ground station is set at 10e6 bits/sec per at the mobile node (or aircraft) as per the top transponder on board the satellite using Yz plot. This is the same profile as that FEC and QPSK. Note in Table 1, it is received by the satellite because of the bent assumed that the Bandwidth occupied by a pipe operation of the satellite already channel with data rate Rb is 2*Rb (which is described. Also the second plot shows the a worse case formula) and hence the S/N received at the aircraft node. Again just bandwidth occupied for 10e6 bits/sec is 20 as in the Uplink verification, we see here Mhz. This bandwidth fits well within one that the values are very similar to Table 1 taking out the polarization effects of 1 db multiple transponders for the satellite and and the atmospheric attenuation of 0.5 db. the ground ends. In the next section, more Note the rain attenuation is not included due comments are made with respect to the to the aircraft being at higher altitudes in the options available to increase overall system En Route phase. With that the numerical capacity in terms of data rates or aircrafts. calculation shows (7.8-1- 0.5)+101og(20e6)=79.3 which is practically the same as the number shown in Table 1. Again the BER are very negligible at the S/N from the QPSK BER vs. S/N standard curves.

Figure 7 Queue build up and empty operation at a typical ground TDMA transmitter.

5. Conclusions and Figure 6: Reception at aircraft (first Plot shows bitslsec throughput, second plot Recomrnendations shows S/N in db) A simulation was built and a proposed architecture was presented for the use of Finally, the plot of Figure 7 shows a AMSS for the ATN. Specifically, the use of typical queue size in packets at a satellite satellite links for the transmission and ground station. As predicted, the queue broadcasting of TIS-B and FIS-B messages builds up until its time for the beginning of was proposed as an alternative to ground the stations time slot at which case is drops based proposals. The architecture considers down rapidly based on the given TDMA use of ground ADS-B mode S, and UAT burst rate. Although the packets arriving transceivers as well as VDL, and secondary from all the ADS-B transmission are random and primary surveillance radars, all for in quantity due to the uniform distribution transmission of ADS-B, CPDLC, and imposed, they average in the mean to values present radar operations. In addition, a that are predictable. If more packets were to single (and if necessary more) satellite be sent (via increasing the mean of the ADS- transponder is used in a bent pipe method B sets transmission, or the number of along with satellite ground stations, one for aircrafts) to values larger than 10, the queue each of the sectors. The satellite earth would have kept building up due to inability stations would collect ADS-B and radar of the TDMA processor to catch up. The information from all the aircraft within its way to compensate for higher rates or larger sector, filter the data to remove number of aircrafts is by utilizing higher redundancies and to create TIS-B messages. bandwidth transponders, or by using The TIS-B messages are then queued along with other data such as FIS-B and FAA, and pilots in making flight transmitted at the TDMA time slots plans, free flight, and scheduling. designated for each earth station. The - The satellite links are reliable for En satellite receiver takes all the messages from Route. all satellite ground stations and simply down links the data which will then be received by - Each transponder on the satellite, receivers on board the aircraft. The present with a data rate of 10 Mbps, is architecture does not require a satellite capable of supporting twenty ARTCC transmission capability on board the aircraft uplink sites, each being fed from 33 (only reception) and hence simplifies the TIS-B ground stations, each relaying satellite as well as the aircraft transceiver ADS-B information from a mean of design. The aircraft receiver will be able to 10 aircraft +/- 40%. With two get the data from any location in the transponders on the satellite each at a CONUS (or satellite coverage area) and it is different frequency, it would be envisioned that on board displays can feed possible to support 660 aircraft per that information into a CONUS, or local ARTCC, with TDMA slots of 0.02 maps which will show the aircraft in a given seconds, with one transponder area. This capability will be useful for free handling eastern traffic, and the other flight planning, for initial flight plans, and handling western traffic. for predicting future traffic patterns at any - Using two transponders each with a location based on the intent messages of the 27 (or higher bandwidths such as 36 ADS-B. Also, last but not least the FIS-B Mhz), it is possible to realize the information will be more readily available proposed design. Hence for a short for not only the local areas but for any area term application it is a cost effective within the satellite earth stations and satellite method that can utilize satellites that broadcast coverage area. The availability of are already in operation by simply information that is not simply localized to leasing one (or if needed more) the aircraft position will be useful not only transponders. Additionally to the pilots for flight planning, but also for redundancy can be achieved by using the airlines, and the FAA center. other satellite transponders for back In summary the advantages of using the UP. satellite links and the architecture proposed - here are among many: While other accessing schemes could have been considered, TDMA is an - broadcast capability to wide areas and acceptable option that is not difficult areas that are outside the range of to achieve especially since the ground ground stations signals such as over stations are fixed nodes (as oppose to oceanic regions. mobile) hence the synchronization is - The reception only (or broadcast not as difficult. TDMA is used in option) requirement for the aircraft many existing satellite architectures simplifies and reduces the cost of the and hence the capability, and aircraft equipment as well as the equipment is readily available. At satellite system itself. The broadcast this point it is also worth noting that a capability of satellites is ideal for dynamic TDMA slot assignment can such an application. also be considered as an option to increase throughput by Having TIS-B, and FIS-B data accommodating the differences in the readily available about any area (or density of the airspace over different within CONUS for a non-global sectors. design) is beneficial for the airlines, - The use of the ground part of this it is more feasible and not as difficult architecture conforms with the (in addition to being a necessity) to accepted standards that are proposing transmit the information. VDL, Mode S and radar for the - While the satellite broadcast can various communications and cover remote areas, oceanic or other, navigations services for the ATN. the lack of ground stations in those - Although in the present architecture remote areas makes the availability of the satellite earth stations were the messages to be transmitted to located at each sector control center, ground (which include ADS-B, UAT, it is possible to reduce the number of CPDLC) an issue. Unless HF them assuming the sectors’ data can frequency is assumed, or a more be shared. Nonetheless, the use of costly satellite uplink design is one satellite station per air sector is available, that disadvantage is there beneficial from many aspects: regardless of the use of satellite links for broadcasting. a- It can provide redundancy in case of weather, service outage, or any other reasons that may require 6. Acknowledgements one of the station to stop The work in this paper was performed operating. as part of the research into Communications, Navigation, and Surveillance (CNS) systems b- For a future outlook where there for the Distributed AirlGround Traffic may be a possibility of utilizing Management (DAG-TM) concept [9]. The spot beams, for uplink capability DAG-TM Concept is funded by the in which case gateways will be Advanced Air Transportation Technologies necessary and hence the (AATT) project office at NASA Ames availability of such stations Research Center at Moffett Field, CA. CNS within each spot beam is useful. studies for DAG-TM are being performed Possible disadvantages of the by contractor personnel of Analex architecture proposed are: Corporation at NASA Glenn Research Center in Cleveland, OH. - For other than En Route, the satellite links can fail with a small percentage when receiving during rain. That is References for altitudes below the clouds (or [ 1l“National Airspace System Architecture- below 5 Km) it is possible that the FAA,”http:l/www .faa. govlnasarchitecture signals will fade causing a loss of [2] Stevens, Michael C., Secondary reception. This disadvantage can be Surveillance Radar, Artech House, overcome at airport locations for the Norwood, MA, 1988. aircraft that are landing or taking off by providing back up ground based [3] RTCA DO-242A, “Minimum Aviation broadcasts via an alternate link. The System Performance Standards for ADS-B”, information in that link could be 2002. localized to reduce data rates until the [4] RTCA, DO-260A, “Minimum satellite signal becomes available. Operational Performance Standards for 1090 Note the rain fade will also effect the MHz ADS-B”, 2002 transmissions of the satellite earth stations, and in that case it is [5] RTCA, DO-282, “Minimum Operational necessary to re-route the data using Performance Standards for UAT ADS-B”, the central ground station to transmit 2002 from else where. Hence in that case [6] Opnet Modeler, Opnet Technologies InC., Bethesda, Maryland, http://www.opnet.com. [7] R. Kerczewski, M. Shamma, R. Spence, R. Apaza, “Emerging Aeronautical Communications Architecture Condept for Future Air Traffic Management Requirements,” 8* Ka Band Utilization Conference, Italy, September, 2002. [SI M. Shamma, “An Evaluation of CDMA and TDMA Communications Architectures for the Aeronautical Mobile Satellite Service,” 21st Digital Avionics Systems Conference in Irvine. California.

[9] AATT Project, ASC Program, NASA, 1999, Concept Definition for DAG-TM, Ver. 1.O, Moffett Field, CA.