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Mar 06 2017

NF9K Technical Specialist Report – February 2017

Provided some assistance to an Indiana HAM regarding the Raspberry Pi. He’s building an AllStar node and also looking into the RTCM units to build out a simulcast system. This will be an interesting project to follow. Last I heard from him, he’s purchased GPS references for each RTCM. Simulcast is nothing without perfect timing.

Continued work on building out the infrastructure for the Indiana Quantar Network (IQN). We opted to go with VPN connections between the core and each site. Doing so eliminated holes in the firewall and static IP requirements. It also makes the entire infrastructure available from a single point. I wrote documentation for configuring the VPN, so that we can keep everything standardized, I still need to write the documentation for the Cisco routers. Our efforts have literally been brick by brick…. As an example, you obtain the proper Cisco router, then you have to buy the right cards for digital and analog audio, the right cables and adapters to connect to your Quantar. You also require DSP resources in your router to run mixed mode, and then there is all the planning for each repeaters ports, subnets, IP addresses, VPN tunnel config, etc. But it’s coming together. As I write this, three tunnels are up and two repeaters on online with a couple more to come very shortly. While the following techinically happened in March, The first official P25 QSO on the IQN too place on 3/4/2017 @ 02:41UTC between K3HTK and NF9K. This was a huge milestone given all the work we’ve put in thus far and really paves the road to shift into overdrive now! We’ve established an FB Group for the IQN (https://www.facebook.com/groups/1742372622743134/) Come join us!

I received a comment via my website from an 8-Call asking about the Henry Amplifiers that I currently use. He was interested in using one for DMR, which I am doing and was curious since the website mentions analog only. Since the DMR repeater brings up both time slots at one time, they will work with most amplifiers, however DMR portables and mobiles will not. Before I purchased the one I have in service, I consulted with the folks at Henry and the confirmed that they work fine with DMR. I shared what I’d learned and my experiences.

Participated as a VE for the WD9BSA VE Team on 2/11/17. We had five come in to test and we gave exams on 10 elements. All in all, we added four new hams to our ranks. (2 General from zero, 1 General Upgrade and one Tech).

As mentioned in last months report, I’ve been working with the developers of the c-Bridge on their implementation of the SIP protocol. In addition to discovering a bug right out of the gate, I found some major issues with release 9032. It would only run for 2-3 days before becoming completely unresponsive. The issue did not manifest itself on a local-traffic c-Bridge as IN-2 had no issues. But IN-1 has the right combination to trigger whatever it is. After multiple attempts and captures of various system stats during the periods working up to a crash, I ended up sending all the data I had to the devs and downgrading to restore system functionality.

On the topic of SIP and the c-Bridge, I’ve successfully been able to initiate a phone call by keying up a talkgroup and conduct two-way communications. Very similar to the functionality of the Echolink client for smart phones. I was able to get the c-Bridge to register as a client to my FreePBX installtion allowing me to pick up a phone and “dial” a talkgroup again establishing two-way communications. I also configured an open conference and had the c-Bridge call and join the conference whenever a talkgroup was keyed up. I then used a SIP phone to also call the conference. The only catch was the conference is designed not to pass DTMF becasue it’s used for conference control, so I could not toggle TX/RX via the phone in this configuration. My next step will be to test with a SIP client on my smart phone. But if all works like I expect, I could offer DMR/talkgroup connectivity to users in a similar fashion to what Echolink does. We’ll see how things go. The IQN is taking a lot of my cycles, but the c-Bridge SIP setup is definitely high on my list of things to work on. I will say that I’m learning a lot on how the c-Bridge works under the hood…. And how to manipulate the system from the linux shell.

Received an email from a 7-Call asking about assistence configuring a Cisco router for P25 Quantar Linking. We exchanged a few emails and I was able to get him on the right path.

Programmed up some Motorola 33cm HT’s (MTX) for a local ham. Which meant I had to dig out the DOS laptop! But it worked fine and after programming one, I was able to do partial clones to the other two. In return, he presented me with a nice Moscato, which promptly went to the XYL. If she’s going to benefit from my work in Ham Radio, shouldn’t she at least get her ticket?!?!?!?!

I was ask once again to present at the Indianapolis Hamfest. They seem interested in another Raspberry Pi presentation. I’d be interested in hearing from folks on what they’d like to see. So if you have any ideas, please shoot me an email (bill@nf9k.net).

I’ve started thinking about building an ADS-B setup similar to what K3HTK has done, but likely without the solar aspect. There is just a cool factor about snagging that info out of the air and displaying it on a map.

When I first started with the IN-1 c-Bridge, Mike Shirley (N07RF) was a huge help. He was a fantastic mentor and teacher and we spend many hours in email, on the radio, even on the phone as he helped me through the learning process. He just recently inquired about SIP capability to the c-Bridge Devs and they referred him to me. The student becoming the teacher is definitely a great feeling and it was awesome to give back to someone who’s given me and the rest of the DMR community so much.

On the same note, I was also hit up my W2AXB, who like Mike, was interested in SIP on the c-Bridge. I was amazed at how quick news traveled that I was working on that stuff. Both guys were looking for the ability to have the c-Bridge function as an autopatch similar to analog repeaters used to do. While the c-Bridge implementation of SIP isn’t far developed, I still have an idea involving an FXO gateway that I’m hoping to try when I can find some time.

Received a website comment from an HK2-Call regarding the DR1X Fusion repeater. He was looking for help regarding the TOT settings and APRS integration. I’m still working with him on these issues.

Helped K3HTK through the process of requesting AMPRNet IP space. We’ll start building routers in a couple of weeks to deliver the IP space to his house…..

Received an email from the Purdue University Amateur Radio Club. They are interested in joining the IQN and after a few emails, we believe the have all of the necessary gear at this point. Once finals are finished for them, we’ll be bringing them online. They will be doing P25 only.

Boy, I think that’s it. It’s been a busy time, but I’m loving every minute of it. Nothing like going downstairs to the Laboratory and walking around looking at things, thinking, I could work on that, or that or this, or…. What a hobby!!!