Steve Hajducek, N2CKH.doc


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Steve Hajducek, N2CKH.doc

  1. 1. Ocean-Monmouth ARC VoIP/IRLP Experiment Presentation 12 April 2003 Presented by Steve Hajducek, N2CKH
  2. 2. This presentation details how OMARC will provide access via the 145.110Mhz club repeater system to Internet based Voice over Internet Protocol (VoIP). Specifically, the Internet Radio Linking Project (IRLP) VoIP system will be utilized. The method of providing VoIP using IRLP as detailed herein to the users of the OMARC 145.110 repeater system on an experimental basis is the simplest way possible to allow the membership to experience the mode and to make their decision as to whether the club should move forward to provide the capability on regular basis. This presentation will also detail how full, automated access could be provided in the future, that would allow each member full command and control of the IRLP should the club decide to implement such a capability. The idea is to allow for access to VoIP as easily and inexpensively as possible on an experimental basis. To begin with, VoIP systems have been around for a number of years now, KB2OPQ first suggested that we implement such a system in OMARC many years ago when the ARRL published the very first article on the subject. Since then the growth of various VoIP systems has been explosive, so has the reception of VoIP within the hobby. There is however both an open and the close mind attitude toward accepting new technology within the hobby, which seems to be very close in both camps as the recent ARRL poll results recently conducted on-line and seen below indicate.
  3. 3. As you can see from the results of the ARRL survey, the two current systems that are the most popular are EchoLink and IRLP. The ARRL also published an article in the February 2003 QST beginning on page 44 titled “VoIP and Amateur Radio” that details the various VoIP systems currently in use. All of the systems are similar in that they utilize VoIP, however there are big differences between some of them. In particular it is only IRLP that requires a radio on both ends of the link, Echolink and the others allow for PC to PC and PC to Radio, which the FCC frowns on. In addition only IRLP provides a 512 bit Pretty Good Protection (PGP) authentication algorithm so prevent hacking into the system. Basically IRLP is as close as it comes to traditional forms of RF, Land Line and Satellite linking without the added costs and with the benefit of wider area coverage. Regarding those recent ARRL survey statistics, looking at the chart, you can also see that of those that responded to the survey of which 5,774 did, 44.0% used a form of VoIP, with EchoLink and
  4. 4. IRLP almost tied, whereas 38.1% have a closed mind attitude ! Then 3.4% did not even know what it was and 14.4% have not tried it, that can probably be attributed to the fact that they had no access to try it out, only guessing though. From the ARRL survey if one wants to draw any conclusions that one could say represents the general attitude of the Amateur community, which I really do not think polls can do, there would seem to be an almost 50/50 split of open and closed minded Amateurs. We have of course seen this attitude regarding AM vs. CW, SSB vs. AM, FM repeaters vs. FM Simplex, Incentive Licensing, No- Code Licensing etc. for years, many just don’t embrace change. In my opinion (we all have one) we need to take steps that welcome change to continue to evolve and exist, not to mention attract the youth into the hobby, and VoIP is a very effective tool to accomplish those goals.
  5. 5. IRLP Statistics: At present there are nearly 900 IRLP nodes worldwide in 30 countries and there are 17 reflectors, each with ten (10) channels for an effective total of 170 reflector channels. Ref Location 9000 Vancouver 9070 Alaska Reflector 9100 Toronto Reflector 9200 Indianapolis 9210 Raleigh 9250 Western Reflector - Las Vegas 9300 Saskatoon Reflector 9310 Fredericton 9350 Los Angeles 9400 Quebec City - GSM Only 9450 Dallas 9500 Sydney - Virtual PUB 9600 Philadelphia 9610 St. John's - GSM Only 9700 Lancaster 9730 Indiana Regional 9800 Scandinavian Reflector All Reflectors now have 10 channels as follows for 9200: 9200 will call primary channel 9201 will call channel 1 9202 will call channel 2 9203 will call channel 3 9204 will call channel 4 9205 will call channel 5 9206 will call channel 6 9207 will call channel 7 9208 will call channel 8 9209 will call channel 9
  6. 6. N2MO EXPERIMENT DETAILS: As detailed in figure 1 below, an RF link to IRLP node 4040 located at the Lakewood hub of N2CKH will be provided as an in- band RF link to the 145.110 repeater system using a modified GE Phoenix transceiver as the link radio. This requires no radio equipment or antenna installation at the 145.110 repeater site. Figure 1. The easiest way to envision this is just think of the IRLP node as a “regular user” of the repeater. The difference being that this “regular user” will be a radio attached to the Linux based IRLP server computer sending the audio feed of one or more other repeaters linked in via IRLP world wide into the OMARC repeater and taking what is being transmitted by local users of 145.110 and
  7. 7. re-transmitting that audio world wide to all systems linked in via IRLP. LEGALITIES: As an ARRL Auxiliary Official Observer I can guarantee everyone that the method of in-band linking with the control operator (myself or KC2KQG) at the Link Radio and IRLP server point of control is 100 percent legal regarding FCC Part 97 requirements. Both FCC Part 97 and the previously mentioned article in the February 2003 QST beginning on page 44 titled “VoIP and Amateur Radio” can be referenced as well. As long as a control operator is present at the link radio at all times and is the only party to have command and control it is legal. HOW IT WILL WORK: The premise of this connection to IRLP during the experimental basis is simple, the control operator at the Link Radio will on a weekly basis (Friday and Saturday nights between 8:00-10:00pm) on schedule, will announce over the repeater what is going to take place and allow anyone that desires the immediate use of the machine to do so. Then the control operator will place the OMARC 145.110 repeater into an IRLP mode via DTMF signaling. Then at the IRLP control point, the control operator will establish a connection to the repeater with one of the IRLP Reflectors or perhaps node to node for about two hours. During this time the IRLP connection may be changed due to activity or lack of it as conditions warrant.
  8. 8. During the IRLP connection, activity taking place on the particular IRLP node connection will be retransmitted over our 145.110 machine and anyone locally can part take in the worldwide IRLP hook up with the output of 145.110 being re-transmitted over IRLP minus locally generated ID’s and brag messages. Should anything take place either remote via the IRLP or locally on 145.110 that would require intervention of the control operator, the link can immediately be terminated via the keyboard of the IRLP Linux server PC by a single keystroke. The Link Radio will have its own 3-minute timeout timer, this goes beyond FCC Part 97 in this case. Also, during the course of each such IRLP session via the club 145.110 repeater, the Link Radio will also periodically ID in CW each 10 minutes during operation, the callsign used will be N2CKH which will be re-transmitted locally. On the 145.110 repeater end, KC2CNB and N2CKH have already discussed the needed configuration of the club repeater for this experiment. During an IRLP session the hang time on the repeater transmitter will be set extremely short and most or all of the brag messages will be turned off. Perhaps a Special “IRLP Mode Active” message along with the FCC required 20 WPM CW ID will be active. This change over in the repeaters personality will take place when control operator at the Link Radio places the 145.110 via DTMF tones into a pre-programmed IRLP mode. After the IRLP session, the repeater will be placed back into normal operating mode and personality.
  9. 9. 145.110 HARDWARE CHANGES: The only hardware changes needed at the 145.110 repeater for this IRLP experimental capability is to configure the PL on the club repeater transmitter to not be present when the repeater sends its CW ID and any recorded messages (all of the recorded messages must be redone to filter out PL tone content in the recordings). The easiest and basically only way to do this with our current controllers is to configure a hardwired mode that enables the PL when ONLY when receiving a signal with PL content as the repeater controllers do NOT support a programmable drop of PL during periods of ID. This means simply that any user of the 145.110 repeater that is operating full CTCSS encode/decode will hear all the activity except for the CW ID and brag messages. Basically this is how the machine has behaved during the winter when we pull encode off the transmitter to prevent our seasonal desense problem, with the exception that brag message bleed through as they have PL content recorded. We will also configuring the long overdue sub-audible tone filter to strip off all tone content from the receiver to the transmitter beyond the COR.
  10. 10. FUTURE OF IRLP ON 145.110: What follows are the details of what can be implemented should the membership make the decision to interface the club 145.110 repeater on a linked basis where the membership can then, on demand, acting as the control operator, be able to bring up and control the IRLP system themselves as desired for VoIP QSO’s with their on-the-fly choice(s) of IRLP node connection. Figure 2. Figure 2 above, details in full, the N2CKH/R planned hub in Lakewood. In the framework of this scheme, the OMARC 145.110 repeater would be “Linked Repeater’s” at about 9 o’clock in the figure.
  11. 11. The RF link would be provided over a dedicated half or full duplex UHF link radio transceiver system donated to OMARC by N2CKH to include the required tuned radio and directional antenna along with feedline of his choosing. In addition, the link radio pair would be coordinated by OMARC via MetroCor for use with the N2CKH/R hub, which is coordinated by ARCC Inc. With a full duplex radio, more control is available, as is more equipment (UHF duplexer and cables) and thus more complication. The benefit of full duplex would be two- way control via the network, that is if the repeater controller at the OMARC site supported such, which at present, it does not. When this system is fully implemented, all of the features of the N2CKH/R hub would be available via the OMARC 145.110 repeater, to include connection to other central NJ repeaters that may be linked onto the hub, IRLP and NWS S.A.M.E. severe weather alerting. (Note: The S.A.M.E. WX alerting system offered for donation to OMARC by N2CKH at the 145.110 repeater site would be automatically disabled during liked sessions due to redundancy.) With the OMARC 145.110 repeater linked via UHF using the repeater controller linking radio port, any OMARC member using DTMF codes would be able to enable or disable the UHF link radio port and once linked to the hub, would be able to communicate with any system already on the linking hub, to include directly making and breaking an IRLP connection if an IRLP connection was not already active.
  12. 12. Figure 3. In figure 3 above, the details of just the N2CKH/R UHF omni- directional linking hub as coordinated by ARCC can be seen. All of the co-hosted repeaters at the Lakewood hub and the UHF linking repeater will float on the Pacific Research repeater controller bus as all of the co-hosted repeaters will use the same make of controller. The AERIALS 443 repeater will also use a Pacific Research (PR) controller. This will allow any user of the network, from any point of access to issue common command and control codes across the network machines using the PR controllers. This would include the OMARC repeater should it ever be upgraded to a PR controller. The OMARC control operators would of course be provided with all the needed hub control codes, many of the current OMARC control operators are already control operators for the Lakewood hub and AERIALS.
  13. 13. In addition, all of the N2CKH/R and AERIALS repeaters will support a mix of PL (CTCSS) and DPL (DCS) codes for various command and control and user access features, this is already true of the N2CKH/R 224.120 and 447.925 repeaters, which are the only repeaters in the area to support DPL. Figure 4. In figure 4 above, the lower right hand side of the figure depicts the OMARC 145.110 repeater with the local S.A.M.E. system integrated. The far left side of the figure depicts the N2CKH/R linking hub in Lakewood and the center depicts any other 3rd party repeaters that may be linked into the hub, such as the AERIALS 443 repeater and planned non-Lakewood N2CKH/R repeaters etc.
  14. 14. Figure 5. In figure 5 above, the entire N2CKH/R hub and all co-hosted repeaters and 6m-satellite receiver system at the Lakewood hub are represented. The lower right hand block represents the off site linked systems. The system also features a single point of access to a telephone line for 911 access on the RI-300 controller the N2CKH/R 2m repeater is depicted on, that 911 access can be made via any point of access to the system just as any other resource, thus via an off site repeater such as the AERIALS 443 machine, when on the hub could make a 911 autopatch. It is the needed new
  15. 15. RI-400 controllers that have been delayed which has slowed the progress in completing the hub as detailed herein. The system supports two IRLP nodes (4040 and 7280) with one which will always on the linking hub for any local co-hosted or remote system to utilize. The two IRLP nodes at the hub can be bridged via the PR controller back plane for special applications, such as bridging two IRLP reflectors together. The system is extensible to add additional local PR controllers and repeaters or more IRLP nodes or link radios to bridge into other RF networks that can’t access the UHF hub repeater for whatever reason. There is no limitation to the number of remote systems that can be linked into the hub. By the way, the UHF full duplex hub repeater is a 430/435Mhz split and it is coordinated for use of an omni-directional antenna, all remote linking radios coming into the hub must use directional antenna and be cross coordinated with ARCC as the hub is based in ARCC territory in Lakewood, Ocean County. The entire hub can be controlled remotely via UHF control receiver, via telephone line, via SSH secure shell over the internet or any local repeater input or remote repeater linked into the hub.