October Engineering Committee Notes

The Engineering Committee took a month off from our regular organized work day, but it was still a productive month.  Here are some of the items the committee worked on.

A new club budget was passed in October and the Engineering Committee asked for approximately $4,200 to upgrade and maintain the repeater systems in 2019.  After the budget was passed by the general membership, we started the task of spacing out the projects with milestone and end goal dates throughout the year.  Agenda items include upgrading old equipment, maintaining the existing equipment and purchasing experimental equipment like the AREDN mesh network for deployment.

One project on the list is repeater linking which is an experimental goal the committee will try and achieve during the first or second quarter of 2019.  In a typical linked repeater, a “back haul” RF radio is used to link systems together. In a 2m repeater system, typically a 70cm frequency is used as this back haul link.  If the link radio was another 2m radio transmitting higher or lower on the band this would interfere with the repeater and potentially making it deaf! Linking via RF also means another radio, more feed line and another antenna at your site, which takes up precious real estate on the rooftop.  RF linking goes back 30+ years and is reliable technology, but there is something new and exciting we can utilize, linking via Ethernet as what it’s called today, voice over IP (VoIP).

Linking with VoIP allows more control, greater features, unlimited linking distance and because of today’s analog to digital converters, the clarity is far superior to RF.  AllStar, an amateur radio system that uses the VoIP protocol to link repeaters and nodes (hotspots) together that is gaining a lot of attention. AllStar VoIP systems are linked together by a $35 Raspberry Pi, Linux software that runs on the Pi (HamVoIP) and a $70 URI dongle which connects into the controller of the repeater or to your node radio.  The committee has been experimenting with this technology in the past few months with great success.

So what makes AllStar any different from Echolink or IRLP which are also VoIP systems?  One main difference is the AllStar system can run without the presence of the internet, which makes it perfect for our SLSRC repeater system.  Between all the repeaters, we have an independent 5GHz network which we will use to link repeaters with these AllStar nodes. Each repeater system we want to link to/from, we will install a Raspberry Pi with an URI dongle.  We will advertise one node (146.850 repeater) on the internet for hams to connect into (like Echolink or IRLP) as this node will act as our hub for the system. If the internet disappeared the repeaters would still be able to be linked together because of our wireless point to point system, so this makes it a very reliable system in a disaster.

Be looking for more updates regarding repeater linking in the coming months about this system we are currently testing.

Items the Engineering Committee accomplished in the month of October;

  • Passed the 2019 budget for $4200
  • Scheduled an AREDN tech talk for Nov 10th to discuss Mesh networking
  • Purchased equipment for two repeater systems for the AllStar network
  • Setup accounts for WØSRC on the AllStar network
  • Completed more documentation regarding the repeater systems
  • Started to setup a PC for proactive network monitoring and alerting

Items the Engineering Committee will accomplish in the month of November;

  • ARDEN tech talk to bring committee members up to speed on Mesh technology
  • Purchase a new Ubiquity 16 port switch for the 9666 Olive Blvd site
    • We are moving the existing 8 port switch to the 200 S Brentwood site
  • Purchase a new CAT800 repeater controller for the 146.850 system
    • This controller will connect to the existing Echolink and IRLP system
    • The old 146.850 CAT1000 controller will be moved to the 146.970 repeater later in the year
  • Install a new Ubiquiti network monitoring system to help notify us of outages
  • Look at installing the WiresX system on the 443.075 machine

If you have questions about the Engineering Committee or want to help volunteer, please see Kyle, AAØZ either at the next SLSRC club meeting, or shoot me an email at engineering <at> slsrc <dot> org.