Boundary County Simulcast System Presentation March 22, 2015

Transcription

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2 Introduction: Slide 2 Boundary County is the northern most county in Idaho. It shares an international border with Canada to the north. The total county population is only 10,800 in an area of 1278 square miles. Everyone in this county wears multiple hats. The fire departments and EMS personnel are volunteers. In this county, when a fire or medical emergency happens, it is imperative that the volunteers can be notified and mobilized quickly. In the past, a single repeater location with a Fire and EMS repeater on Dawson Ridge was used to notify the volunteers county wide of an emergency. These single repeaters had poor coverage in the downtown area of Bonner s Ferry, the largest city in the county, and in the southern part of the county. There was essentially no coverage in the northeast corner of the county where Highway 95 crosses into Canada. Page 2

3 The Quasi Sync 2 (QS2) simulcast system was implemented to improve the response time in mobilizing and dispatching the volunteer Fire and EMS personnel and providing a link between the EMS paramedics and the hospital. QS2 was chosen because of its coverage and its operational simplicity. This county has a very small economic base, and nearly all the money for the system was provided by three grants. This meant there would be no additional money outside of the grants, and we had to provide the biggest bang possible for the dollars available. took a risk in implementing the first MiMOMax link used in a QS2 system. We also took a risk by implementing an Exalt 11 GHz Microwave Link without SynchroCast III to insure link timing. Tait believed that the Exalt link would work with its native TDM and native Ethernet topology, but it was untested. Thankfully both systems seem to work very well. System Topology: Slide 3 Page 3

4 The topology of the county is a mixture of high mountain ridges and valley corridors where most of the population resides. The simulcast system consists of three simulcast locations. Each of these locations has a Fire dispatch channel and an EMS channel. The forth location has a single EMS channel, operating sloppy-cast. Dawson Ridge: The central head end site of the system is on Dawson Ridge. This is where the original repeaters for the county were located. Dawson s 120 foot tower provides broad VHF coverage of the area, up the Kootenai River Valley into Canada and down the US Highway 2 corridor into Montana. Dawson is also where the Tait QS2 system controller and monitor receiver are located. The Dawson tower also provides the central point for the 932 MHz MiMOMax link to City Tower, 932 MHz MiMOMax link to Copper Creek, and the 11GHz Exalt microwave link to Fall Creek. City Tower: The City of Bonner s Ferry is covered by the 100-foot City Tower located on a bluff east of the city inside the city maintenance yard. The 932 MHz MiMOMax link to this location is the first time MiMOMax has ever been used in a QS2 Simulcast system. Fall Creek: The 100-foot tower at the new Fall Creek Fire Station #3 covers the southern portion of the county. This location provides internet access to the system and is where the system Ethernet router and the system monitoring computer are located. The backhaul to this site is the 11 GHz Exalt Microwave Link. Copper Creek: The Copper Creek is a solar and wind powered site with propane generator backup. It is located on the side of a mountain in the middle of a grizzly bear habitat. This 5 watt sloppy-cast site was designed for minimal power consumption. A 2-bay reflector-backed folded dipole antenna is used to control the antenna pattern and minimize interference with the rest of the system, while providing coverage into the northeast corner of the county. The backhaul MiMOMax link is configured with optional Transmit-on-Demand to minimize power consumption. Copper Creek does generate two areas of simulcast interference because it is a sloppy-cast site. One area is along the northeast corridor on Hwy 95 through the hills. The second is along the road south of the Copper Creek site. Page 4

5 City Tower Block Diagram: Slide 4 The block diagram of the City Tower site is typical of the QS2 sites in the system. Each of the sites has VHF multicoupler and power combiners which can be expanded to 4 VHF channels. Each of the two RSUs have their 1pps GPS timing references linked together in case one of the references fails or their GPS antenna is blocked from receiving a sufficient number of satellites. The SecureSync GPS Master Oscillator Antenna is shared with one of the RSU s GPS antenna through an amplified GPS antenna splitter. The two RSUs are each connected to a TB8100 Base Station. A second channel card can easily be added to each of the RSUs for a total of four VHF channels. The Ethernet switch connects the Ethernet backhaul to the base stations, power supply, and the SecureSync Master Oscillator. Page 5

6 Dawson Ridge QS2 Block Diagram: Slide 5 Each of the four locations has a different type of interface into the QS2 shelves and voting system. Dawson s 4-wire RSU and 2-wire monitor receiver interfaces are connected directly into the QS2 shelves. The Fall Creek RSU 4-wire interfaces come through T1 interfaces of the 11 GHz microwave link and are decoded by the GatesAir Intraplex 4-port PCM E&M Voice Module before they are connected into the QS2 Shelve. City Tower s RSU 4-wire interfaces connect through the MiMOMax Audio Interface into the QS2 Shelf. The E&M connection from the Copper Creek EMS base station connects through the MiMOMax link to the E&M input on its voters channel card. It is sloppy cast and does not go through the QS2 Shelf. Raytheon SNV-12 voters vote from left to right. The voter will stop searching once it has found a signal which meets its voting criteria, even though it may not be the best quality signal. Placing the main site channel card in the left most card slot tends to have the voter favor the main site, even though it may not be Page 6

7 receiving the best signal. The City Tower was placed in the left most card slot to insure the downtown area has the best signal quality possible. Copper Creek Block Diagram: Slide 6 Copper Creek is designed to operate with minimal power draw from the -48VDC solar/wind/backup propane generator power system. The site is a microwave relay owned by the Boundary County Television Translator District. The MiMOMax and the TB8100 base station receivers draw ~28 watts in standby mode. The power draw jumps to ~138 watts when the site receives an EMS VHF signal, with both the TB8100 base station and the MiMOMax transmitting. The MiMOMax link will return to receive-only mode15 seconds after either the E&M audio channel or the Ethernet has finished sending information across the link. Note: The base station output relay is closed whenever a valid TOR signal is received on the EMS channel. The relay closure drives the E-Lead (signal input) of the E&M interface high, and signals the voter across the MiMOMax link that a valid signal has been received and is available on the 2-wire audio output. The voter decides among the valid inputs which signal is the best. The best signal is Page 7

8 then sent back across the MiMOMax link 2-wire audio input line to Copper Creek. The transmitter is then triggered by the MiMOMax M-lead (signal output). 932 MHz MiMOMax: Slide 7 The cost of a Boundary County MiMOMax link was about 25 % less than the 11 GHz Exalt microwave. This is considering the coax and cable, lightning arresters, T1 multiplexers, antennas and everything it took to put together both links. The MiMOMax does require an External Duplexer to achieve a 9 MHz TX RX channel spacing. Public safety application should have both ends of the link licensed. The 900 MHz licensed band has 9 MHz channel spacing. This raised the cost of the MiMOMax Link. The 11 GHz Exalt Microwave link was one of the few native TDM T1 links available which could probably maintain its timing delays, without using a SynchroCast III timing board in the Intraplex T1 MUX. This was a huge savings. MiMOMAX could be as low as 50 to 60% of the cost of an 11 Page 8

9 GHz microwave link depending upon the microwave radios used for the link and if SynchroCast III is required. The MiMOMax and Tait worked together to create a software package which has enough timing stability to be a reliable backhaul for a QS2 system. A 932 MHz, 25 khz channel bandwidth can support 4 each, 32kbps Audio Channels and a 34 kbps Ethernet per link, simultaneously. The E&M audio interface supports an optional low power mode. The transmitter is held off unless there is data to be transferred over the Ethernet or the E-lead is triggered on the E&M interface. The temperature range of the RF Outdoor Unit is: - 25 C to +60 C (-13 F to +140 F). This temperature range is insufficient for use outdoors in Boundary County, so ½ heliax was required between the antenna and radio. The dual polarized 16 dbi panel antenna has a beam width of ~20 Horizontal, 34 Vertical. The wider beam width makes antenna aiming and tower movement much less critical. The microwave antennas used in Boundary County have 2 beam widths. It required changing the guy wire configuration at Fall Creek to minimize the torsional movement of the tower in the wind. Copper Creek to Dawson: RX1= 23dB, RX2 = 24dB fade margin, 10.9 miles Dawson to Copper Creek: RX1 = 22dB, RX2 = 21dB fade margin, 10.9 miles City Tower to Dawson: RX1 = 27dB, RX2 = 27dB fade margin, 6.7 miles Dawson to City Tower: RX1 = 30dB, RX2 = 24dB fade margin, 6.7` miles Fade Margin Reference Level: -85dBm with 10^-7 BER Page 9

10 11 GHz Exalt ExploreAir (TDM) Link: Slide 8 TAITNET QS2 was designed for four wire interconnections. Anything used to link QS2 must provide the four wire characteristics, must provide PCM coding (no vocoding that could potentially distort the complex training waveform), provide less than 49 ms of delay, and provide constant delay (jitter less than 2 us). The Exalt ExploreAir provides a low jitter, Native TDM for their T1 interface, and a separate Native Ethernet. A GatesAir Intraplex Interface is used to convert the 4-wire audio to and from the T1 interface on the Exalt radio. The Exalt characteristics appear sufficiently stable that SynchroCast III was not required to stabilize the link timing delays. If the link is part of a redundant loop which would change the time delay when the loop changed direction or the data is transported via Ethernet, then SynchroCast III is required. The microwave link was set for a data rate of 94 Mbps in each direction with QAM 16 modulation in a 30 MHz wide channel. It could carry a maximum of 4 T1 Page 10

11 lines. Each T1 line has a capacity of 24 64kbps PCM audio channels. The link can carry 87Mbps of Ethernet traffic in addition to the 4 T1 Lines, simultaneously. The microwave radio is mounted directly to the 3-foot dish antenna using a waveguide interface. The radio s temperature range is - 40 C to +65 C (-40 F to +149 F) which is sufficient to meet the climate conditions of Boundary County. Fall Creek to Dawson: 29dB fade margin, 17.2 miles Dawson to Fall Creek: 29dB fade margin, 17.2 miles Fade Margin Reference Level: -77dBm with 10^-8 BER In September of 2014, Exalt Communications was shut down for a short period of time while its management successfully negotiated a buyout of its initial venture capital investors, subsequently re-establishing the company as Exalt Wireless. The majority of their product line will be available on the Hutton web site soon as Hutton and Exalt are in the final phase of signing a distributor contract. Copper Creek, Fall Creek and Dawson Racks Slide 9 Copper Creek is the sloppy-cast site and has no simulcast timing. It was important to see that this site was working properly across the MiMOMax Page 11

12 backhaul and was adjusted to the proper signal levels without interfering with the simulcast testing. The Duplexer antenna output was terminated in an hp 8920A during in-shop testing. (The Fall Creek power supply powered the Copper Creek rack during the testing.) Fall Creek The combiner output was attenuated by 20 db during testing before it was connected to a whip antenna in a room at the far end of the building. The multicoupler antenna was put in the same room during testing. Dawson The VHF antennas were located in the same room as the racks, with the combiner output attenuated by 20 db with a whip antenna during testing. The initial testing of the GatesAir T1 Multiplexers was done using a T1 Crossover cable. It was here we found an error in the T1 Mux Configuration which was easily solved with a little help from Steve Paulson at GatesAir. Microwave and City Tower Testing Slide 10 Microwave Links can be tested indoors provided they are set to minimum power levels in an unoccupied room. The T1 Crossover link used to test Page 12

13 the phase shift of the Gates Air Multiplexer was replaced with the T1 Connections of the actual Exalt microwave links, allowing end-to-end audio phase shift verses frequency testing. The City Tower The combiner output was attenuated by 20 db during testing before it was connected to a whip antenna outside the building. The multicoupler antenna was also put outside during testing. Dawson MiMOMax link was also tested end to-end using 120dB switched variable attenuators in each RF path. The audio Phase shift vs. frequency confirmed a fixed path delay of ~6ms. Dawson Master Site Slide 11 The master site was built such that it is easily expanded. There is space allocated in the rack for two more VHF channels and the required QS2 shelves and voters. The multicoupler and the combiner already have three channels, and the design permits easy expansion for a forth channel. The power supply system is sized for the additional load and the Ethernet cabling was added to the cable harnesses. There is also room and cabling for a third MiMOMax link allowing the addition of a fifth site location. Page 13

14 Fall Creek Fire Station Site Slide 12 Fall Creek is the location of the system monitor computer. The addition of a third and fourth VHF Channel will be accomplished by adding a third rack which will contain the additional cavities for the Multiplexer and combiner and the two additional TB8100 base stations. Page 14

15 City Tower Site Slide 13 City Tower was installed in an un-insulated cargo container supplied by the County s limited budget. We discouraged the County from installing the equipment in the un-insulated container because of undue stress of winter freezing and summer baking on the equipment. Hopefully the County will insulate the container and install the HVAC in the site as soon as possible. The addition of a third and fourth VHF Channel will be accomplished by adding a third rack which will contain the additional cavities for the Multiplexer and combiner and the two additional TB8100 base stations. Page 15

16 Copper Creek Site Slide 14 The Copper Creek Site is designed for minimal power consumption. The site s standby power consumption is ~28 watts from the -48VDC power system compared to ~160 watts consumed at City Tower. The site will not be expanded unless AC power is brought to the site. Copper Creek could become a full simulcast site if AC shore power becomes available. Page 16

17 Dawson Tower Slide 15 The Dawson tower has been on the site for at least 30 years. It is a 120- foot star guyed communication tower stabilized for point-to-point microwave links. The simulcast VHF 4-bay folded dipole multicoupler receive antenna is mounted at the top of the tower with a northwest southeast bidirectional antenna pattern. The top of the simulcast VHF 2-bay folded dipole combiner output antenna is mounted 25 feet below the receive antenna providing ~52 db of isolation. It has the same northwest southeast bidirectional antenna pattern as the receive antenna. The MiMOMax 36.6 x 19.7 panel antenna to City Tower and Copper Creek are at the Intraplex 90-foot level, spaced 2 feet off the tower. The 11 GHz 3-foot dish to Fall Creek is mounted at the 70-foot level. Page 17

18 Fall Creek Tower Slide 16 The 100-foot Fall Creek Tower was built by another company before the simulcast system was decided upon. It was not built with the torsional stability required to hold a 3-foot microwave dish stable within +/-1 degree in the wind. The tower had to be re-guyed in a star guying configuration at the top to provide a stable platform for the microwave dish. The simulcast VHF 4-bay folded dipole multicoupler receive antenna is mounted at the top of the tower with a northwest southeast bidirectional antenna pattern. The top of the simulcast VHF 2-bay folded dipole combiner output antenna is mounted 40 feet below the receive antenna providing ~58 db of isolation. It has the same northwest southeast bidirectional antenna pattern as the receive antenna. Note: Setting the azimuth of a microwave dish can be a challenge. The technique we used at Dawson Ridge was to sight on City Tower, and then we adjusted the dish 6 to the left to point to Fall Creek. Page 18

19 The azimuth of the microwave dish at Fall Creek was adjusted by tying a heavy string to the base of the tower, directly below the dish. About 100 to 150 feet from the tower, a 5 inch nautical compass was used to set the string on the bearing to the Dawson Tower. The string was pulled taught across the face of the compass. The position of the compass and string was adjusted until the string went through the center of the compass and the correct bearing adjusted for the magnetic declination. Once the correct bearing had been established, I stood on the string and directed the tower crew to adjust the dish such that its azimuth was directly at me. We managed to establish a link using just these techniques with 3-foot dishes with 2 beam width. Once the link was established, it was optimized at both ends. City Tower Slide 17 The 100-foot City Tower is a heavy duty self supporting tower built to provide wireless internet to Bonner s Ferry. The simulcast VHF 4-bay folded dipole multicoupler receive antenna is mounted at the top of the tower with a north south bidirectional antenna pattern. Page 19

20 The top of the simulcast VHF 4-bay folded dipole combiner output antenna is mounted 20 feet below the receive antenna providing ~48 db of isolation. It has the same antenna pattern as the receive antenna. The goal of City Tower is to produce as much radiated power as possible in and around Bonner s Ferry to insure FM capture effect. The MiMOMax link was visually aligned and adjusted with the Dawson Ridge site. Copper Creek Tower Slide 18 The 40-Foot self supporting tower at Copper Creek was built to provide a TV translator. The tower is built heavy enough to support an 8-foot diameter wind generator at the top. The MiMOMax Link is mounted at about 38 feet, pointed toward Dawson Ridge. The VHF 2-bay folded dipole with reflector antenna is mounted on the back side of the tower away from Dawson at about 15 feet in hope that the tower will help provide some additional shielding to the south. The VHF antenna is pointed toward the northwest and pointed 10 down to minimize the amount of power being sent into Canada. Page 20

21 Things Done Well Slide 19 The System was designed for planned expansion. It is reasonably likely that in the future Channel 3 will become a county wide tactical fire channel. The multicoupler and combiner at Dawson already have this channel built into it. The channel currently is the tactical channel for one of the local fire departments. The forth channel will possibly be used for law enforcement dispatch. The Monitor Computer provides remote access and control of the system. Usoris System Viewer Software provides access to the monitor computer. The viewer can access the computer directly through the computer s IP address from the system sites locations or through the internet. The Kiwi Server software sends alerts generated in the remotely accessible equipment to the system administer to inform a technician of a pending error or problem with the system. Remote Access has enabled us to monitor, track and solve problems in the system. The ability to remotely train the QS2 system as well as look at the QS2 fault and training logs allows us to remotely monitor and track the Page 21

22 health of all the links in the system. The system will log and time-stamp any link fault of more that 15 seconds. Access to the backhaul links and their logs provides remote access to the current fade margin in their links. Monitoring the power supply power temperature allowed us to see what the local temperature was in the sites last winter. Documentation: I have worked to keep all of the major documentation current, so the next QS2 system we design will go faster and easier. Accurate documentation also makes troubleshooting system problems much easier. Things Not to Do Slide 20 Do not have the Main Site s Channel Card in the left most slot of a SNV- 12 Voter. The voter votes from left to right and it will choose the Mains Site whenever possible, although it may not have the best signal. Do not connect all of the RSU GPS Antenna Inputs into a single antenna distribution amplifier and GPS antenna. It does not provide spatial diversity between the two GPS receivers. We had to go back and add a second GPS antenna for the second RSU in each site. (The SecureSync Page 22

23 can share one of the GPS antennas because even if it loses the satellite lock for an hour its internal reference will keep it on frequency.) Do not mount a microwave dish at or near the top of a tall guyed tower without providing a star guy wire configuration to torsionally stabilize the tower. The Fall Creek microwave dish has a 2 beam width. The tower can twist in the wind, dropping the fade margin from nearly 30 db down to 2 or 3 db. Do not install a simulcast system into an un-insulated metal shelter. Simulcast system equipment is not designed for extended operation in temperature extremes which may compromise its reliability. System Coverage and Results Slide 21 Original System One site on Dawson Ridge -1 repeater for Fire and 1 repeater for EMS. New System 3 Simulcast sites for Fire and EMS and 1 Sloppy-cast site for EMS Improvements from the new system Overall portable coverage is much better. Page 23

24 City Tower greatly improved portable coverage around Bonner s Ferry where coverage was poor. Fall Creek greatly improved the coverage in the southern part of the County, especially along Hwy-95 where there was poor portable coverage and numerous traffic accidents. The northern part of the County borders Canada and is very mountainous. There had never been portable coverage and only poor mobile coverage at the Eastport Border Crossing before installation of the new system. The Copper Creek solar site now provides portable and mobile coverage at the border. The Customer is very happy with the coverage of the new system. Page 24