CB FM and APRS?

The FCC recently authorized the use of frequency modulation in the Part 95 11 meter Citizens Band. This action was in response to a petition filed by Cobra Electronics. This change, a clear attempt to generate sales of radios for CB radio manufacturers, could well breathe new life into CB radio.

I think the FCC made a mistake, however, by mandating that new radios having FM capability also have AM capability. While this is intended to provide backward compatability, it would probably be better if the FCC had sunsetted use of AM a few years out. Then we’d be rid of the heterodynes and squeals caused by too many AM signals on the same frequency at the same time.

In the same Report and Order, the FCC authorized the use of position reporting systems on the CB band. Expect to see APRS-like reports using packet FM from GPS enabled portable and mobile radio.

I suggest that we watch for increased interest by the general public. There could be a revival of CB radio as it becomes more usable for local communications. No, we’ll never have a resurgence of the 1970s CB boom, but static free local communications at low cost is going to be attractive to a lot of folks.

73 de K2IE

Fun & Games With 3rd Order IMD Products

A local group of hams has been talking on 2 meter FM simplex for as long as I can remember. In recent years, they’ve been using 146.4 MHz as their primary frequency. I recently ran into one member of the group on a local repeater trying to test something. I responded to him, in case he needed assistance. He he told me how the local repeater on 443.200 MHz was bleeding into conversations on 146.4. Trying to be helpful, and knowing who to get in touch with on the tech side of 443.200, I got involved.

The 443.200 repeater in my area is linked to 146.76 MHz. I surmised that 146.76 was the actual culprit. At my location, 10 miles from the repeater, I could not hear the interference. The hams that are being interfered with are much closer to the repeater site than me. They provided links to some recordings and I gave them a listen.

I noticed that in addition to hearing the audio from 146.76 I also heard mixing from 147.12. I reported that to some of the folks at the club responsible for 146.76 as well as to the owner of 147.12. I observed that 147.12 – 146.76 = 0.36 and that 146.76-146.4 also = 0.36. This seemed significant to me although I did not know what it represented. The club president chimed in with the determination that the 2 repeater output frequencies, when mixed, generate a third order intermodulation distortion product on approximately 146.4 MHz. Wow!

From my reading, a third order IMD product is created when two non-linear signals mix. To me, that indicates a problem at one or both of the repeater sites. Some local hams familiar with the situation voiced the opinion that there is no way to fix this for stations close to the 2 repeaters (which are also relatively close to one another). I was told that at least one of the repeater keepers was also heard expressing this position. Based upon my understanding, I initially disputed the “nothing can be done” position with the thought that if the cause is non-linearity, something can and should be done.

Today I tried an interesting experiment. I took 2 HTs which are probably fairly spectrally pure (a Kenwood D74A and a Yaesu VX7R). I set them both to one watt and put a receiver on 146.4 MHz. One radio transmitted on 146.76 and one on 147.12 MHz.

If I keyed up one radio without transmitting on the other, no signal was heard on 146.4 MHz.

However, when I transmitted on both frequencies simultaneously a perfect signal was heard on 146.4 MHz!

If this behavior can be so easily reproduced with two (supposedly) spectrally pure transceivers and provides the same result on multiple receivers — an RTL-SDR stick and a Kenwood TS-2000– there may just be something to the “nothing can be done” school of thought.

73 de K2IE

The Best Time Synchronization for Windows

The best way to synchronize the time of your Windows based PC is not a third party add-on. It is to use the capabilities built into Windows 10.

I have read numerous threads in amateur radio forums about time synchronization for digital modes such as FT8 and FT4. These usually turn into long threads recommending this or that third party solution. None of them are needed.

Here is the solution that I use. It requires only Windows 10.

Open a Windows 10 command prompt as administrator and run the following commands. These stop time synchronization and resets the service to some defaults settings.

net stop w32time
w32tm /unregister
w32tm /register

Next, run regedit. Carefully make the following changes.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w32time\Config\MinPollInterval
     Set to 10 decimal

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w32time\Config\MaxPollInterval
     Set to 15 decimal

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w32time\Parameters\NtpServer
     Set to time.windows.com,0x9
     If you have a different server you want to use feel free to do so

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\w32time\TimeProviders\NtpClient\SpecialPollInterval
     Set to 1800 decimal
     This will update the time every 30 minutes
     You may have to create this key

If your computer is not attached to a domain (normally the case for non-workplace computers), make sure that time synchronization is automatically triggered when your computer is on the network.

sc triggerinfo w32time start/networkon stop/networkoff

Finally, restart time synchronization.

net start w32time

This restarts the time synchronization process. Your time will be synchronized to the ntp server that you specify every 30 minutes.

You can check your work with the following command:

w32tm /query /peers

The output will show that you are synchronized and to what server. I run a local GPS time source. This is what my output looks like:

Peer: ntp.private,0x9
State: Active
Time Remaining: 0.0000000s
Mode: 3 (Client)
Stratum: 0 (unspecified)
PeerPoll Interval: 0 (unspecified)
HostPoll Interval: 10 (1024s)

Peer: ntp.private,0x9
State: Active
Time Remaining: 1784.6442139s
Mode: 3 (Client)
Stratum: 1 (primary reference - syncd by radio clock)
PeerPoll Interval: 17 (out of valid range)
HostPoll Interval: 10 (1024s)

73 de K2IE

The Importance of IPv6 in Amateur Radio

What most of us call an IP address, in the form 1.2.3.4, is really an IP Version 4 (IPv4) address. IPv4 has a serious limitation. The largest number that can be respresented in the 32 bit binary value of an IPv4 address is 2 ^ 32 (4,294,967,296). Believe it or not, these addresses are in short supply.

IPv6 was created as a solution almost 23 years ago. An important specification document was published in December 1998. IPv6 World Launch Day was 10 years ago! IPv6 is not new. IPv6 provides 2 ^ 128 (340 trillion trillion trillion) addresses. So why aren’t we all using IPv6 now?

Aside from a bounty of address space, there are other reasons to adopt IPv6. Large network providers have built new and optimized infrastructure with IPv6 in mind. Here’s an example of how this can work to your advantage.

The 020 Digital Multiprotocol system has bridge to the Brandmeister DMR (BM) system. Low network latency is of critical importance in delivering high quality voice connections. Any network latency created issues are amplified when voice transmissions are passed through multiple applications and protocol transcoding hops.

Using the IPv4 network, ping time between our end of the bridge and BM is about 8 ms. That is actually pretty good. IPv6 blows that away, with about 1.5 ms ping times. That reason was good enough for me to get my hands dirty and modify some Python code to be IPv6 capable.

IPv6 also helps with the problem of NAT and port forwarding on residential routers. Simply put, NAT can be thrown into the trash bin of computing history. Instead of just one address, the minimum network assignment under IPv6 is 64 bits. That is 2 ^ 64 addresses!

Several ham software authors and volunteers are working on updating their software to be IPv6 capable. My amateur radio wishlist for full IPv6 capability includes xlxd, DMRGateway and ircDDBGateway. HBlink will be there once my pull request is merged. That is the Python code I referred to that links the 020 world to Brandmeister.

N7TAE has a functional QnetGateway using IPv6. I could not get it to work with my DVAPs and will need to followup up with Tom, but he has provided a wide range of hardware support including MMDVM devices.

There are a lot of bits and pieces that will be involved with updating amateur radio software, much of it ancient, to IPv6. So let’s start now. This will take time. And, if you’re a ham working on some new software for the amateur radio world, please make sure that it supports IPv6 out of the box.

73 de K2IE

Net 44 and Icom Terminal Mode

Since before the days of the commercial internet, amateur radio operators have had their own Class A block of IPv4 addresses. Net 44 or AMPRNet is a non-routeable amateur radio experimentation network and access is only available to licensed radio amateurs around the world.

While hams have been experimenting with Net 44 since the early days of packet radio, interconnecting RF and wired networks via AX.25, I’m a relative newcomer. A couple members of the 020 Team are up and running on the AMPRNet and looking at potential use cases.

My driving use case is the to get around the limitation of one ircddbgateway behind a single network address translation (NAT). This limitation prevented me from running an ircddbgateway to service my Pi-Star hotspots and to use Icom Terminal Mode on my IC-9700 at the same time. What is the limitation? UDP port 40000, used by the ircddb protocol, must be forwarded to the destination system. As the Highlander said, “There can be only one.”

By establishing a Net 44 subnet behind my firewall and assigning a Net 44 address to the Icom, I get around the single IP NAT limitation. There’s a bit more to this, but a Net 44 gateway can be run on a spare Raspberry Pi or your internet gateway router (or any Linux based host). This article is not, however, meant to be an implementation guide but more of a starting point for thought.

It is also an announcement that XLX020 is now available on the AMPRNet for use by those with Icom Terminal Mode radios. Our gateway address on the AMPRNet is 44.64.12.57 and you can connect to any module using a To Call of /XLX020m (replace m with your module of choice). If you’re on Net 44, feel free to connect.

73 de K2IE

Optimum Lowers Boom on TiVo

We were afraid that this would happen and it did.

The Federal Communications Commission (FCC) recently removed its mandate for cable providers to support cable cards and tuning adapters. While the technology is old and not without issues, it is a way for customer owned devices to view cable programming on their own device, such as a TiVo. It also gets the customer out of paying for a cable set top box.

For several weeks, I’ve been having a problem with an Optimum/Altice provided tuning adapter constantly rebooting. This has prevented me from watching channels delivered via switched digital video (SDV). It has also caused my TiVo to temporarily malfunction as the cable card attempts to remap channels each time the tuning adapter is not seen as available by the TiVo.

After numerous calls, disconnects, outright lies by customer service reps, and 2 FCC complaints, Boris from Optimum called today and said they do not have a replacement tuning adapter for me and that my only recourse is a cable box.

Here is the an excerpt of an email that I received as a followup to the call.

As per our today conversation, we need to inform that Channels that use Switched Digital Video technology are not available when using a CableCARD with a TiVo CableCARD-compatible device. These customers will need a digital set top box to view Switched Digital Video Channels.
Tuning Adapters are no longer available in Altice East Retail stores.

Also of interest to some readers:

In the Hudson, Newark / Elizabeth and Paterson service areas, we do not deliver programming through SDV technology.

This is not good. Wonder what TiVo’s play is going to be here? Wonder which providers are next to drop tuning adapter support.

As for me, at least I’m in a good over the air (OTA) antenna area.

When Customer Service is Not Optimum

My cable internet provider is Altice USA a/k/a Optimum Online a/k/a Cablevision. Over the years they have generally been reliable, at least in my experience. However, I recently had a terrible customer experience with this company. The matter was ultimately remedied, but only after I escalated matters to the fullest extent possible.

In addition to internet services, I get a Broadcast Basic package of mostly over the air channels. I don’t actually need the package because I have excellent free over the air (OTA) reception of all of the NYC based stations. Much of the regular programming that we watch is via streaming services and I can always get CNN or MSNBC audio via TuneIn or Sirius XM. But, the Broadcast Basic service also provides the essential public service broadcaster, CSPAN.

The main reason that I take the package is that at some point it turned out to cost the same for a TV/Internet bundle as the Internet alone. So why not? The package also provides some decent music channels provided through a service from Stingray.

On or around May 22nd, in the midst of COVID-19 isolation here in New Jersey, a large number of the channels in my TV package disappeared. And so began 21 days of dealing with mostly outsourced, ignorant and even obnoxiously overly-gracious call center representatives (CCR). They wasted about 20 hours of my time and did not solve my problem.

This is a good time to mention that I don’t have or need a cable box. I own a TiVo DVR with lifetime service plan. The Tivo box has a CableCard slot. It is a nice compact package.

On day one of the outage, almost all of my channels disappeared for a time. Within hours, the broadcast HD channels had mostly returned. Then I began to notice that some channels were still missing. When I phoned customer service, I was told that they were aware of an outage and that I would be called when it was cleared. No one called.

This was followed by call after call. I was told that my problem had been resvoled, when it had not. I was told to reboot my cable box which I do not have. I was told to uplug and replug my TiVo box. I took many passes through an interactive voice response (IVR) system that does not understand CableCards.

At various points, I figured out how to bypass the IVR’s automated troubleshooting process and get to a human rep. The reps repeatedly paired and unpaired my CableCard without acheiving the desired result. Something must have changed on the Cablevision network.

I started talking to others in my area and learned that my problem was not unique. As I researched the problem, I suspected that the missing channels had been changed over to a switched digital video (SDV) protocol. SDV allows the providers to save bandwidth by sending less frequently used video out on demand only. Unfortunately, CSPAN does not seem to be viewed as often as it probably should be.

It seems that a CableCard cannot received SDV channels. An external box termed a tuning adapter is needed to receive the SDV channels. The only call center represtative that might have understood the issue was so obnoxiously and facetiously gracious that it was painful to speak with him. Oh Mr. Dan, speaking to you is the high point of my day…that sort of thing. Repeatedly. I would characterize this as a culture clash with the subcontinent call center.

He offered a tuning adapter as a solution but quickly retracted that offer, saying instead that he wanted to send me new cablecard or to dispatch a technician to my home to troubleshoot my cable. Nope, no way, not in the middle of a worldwide pandemic. No thank you.

Around day 17 or so of the outage, my daily call to the less than Optimum customer service revealed that I could obtain a tuning adapter to see if it solved my issue. I was told to go to the Parlin store to pick it up. I asked the CCR to call the store first to make certain that they had one in stock and that I was not wasting a trip. I have not been out on many shopping expeditions since the 21st of March and I would have preferred that they ship the tuning adapter to me. I was told that they can’t, which would have been more accurate had they said they won’t.

The CCR assured me that a tuning adapter would await me in Parlin. After a 20 minutes drive, I arrived outside the Parlin store. Customers were not being admitted but there was a gentleman at the door answering inquiries. He politely informed me that the had not seen a tuning adapter in that store since November.

At that point, my only option was to go vertical. I filed an FCC complaint, a NJ BPU complaint, and found email addesses for a number of corporate executives. The next day I received a phone call from Tom, a nice fellow who works for Corporate Customer Relations.

He was very apologetic about the company’s poor response to that point. He acknowledged that the outage was indeed caused by a conversion of certain channels to SDV. He arranged for a tuning adapter to be delivered to my house and asked me to call him personally when it arrived to have it provisioned. That happened yesterday, on schedule, and after a 21 day outage I now have all channels to which I am entitled.

This was a major customer service failure that could have been prevented had Optimum provided clear scripts and training to their CCRs that would have immediately pointed them to a solution for missing channels when using a cablecard. Engineering should also be providing the CCRs with a clear change calendar that shows when regions are being converted to SDV or any other major changes are being made so that related incidents are immediately associcated.

And there is a lesson here about outsourcing. It may be cheap, but you get what you pay for. And in the end, it took a technically knowledgable guy from Long Island to solve my issue, not a contractor in Bangalore.

Only a virtual monopoly can get away with providing such poor service and still survive.

Amateur Radio Guide to Digital Mobile Radio

A comprehensive introduction to DMR is available to hams at no cost, thanks to the efforts of John Burningham <W2XAB>. His “Amateur Radio Guide to Digital Mobile Radio” won the 2016 Technical Achievement Award at Dayton Hamvention and the second edition was published in 2019. Even if you think you know how DMR works, this guide is full of useful information.

If your view of DMR is limited to the perspective of Pi-Star and Brandmeister or TGIF, this free book tells the rest of the story in its 27 pages. It is an easy read and will enhance your DMR knowledge.

Duplex Hotspot Reliability Revisited

Last August, I presented a solution for the “lost transmission” syndrome when using an MMDVM duplex hotspot. Several members of the 020 Digital Multiprotocol Group and I remain dissatisfied with our overall user experience. Granted, fewer transmissions are being lost than at first, but overall the number of transmissions during a longer QSO that fail to properly negotiate with the hotspot are higher than we’d like.

Earlier this week, 020 member Scott <KB2EAR> did some further digging and came up with aditional ideas found on the interwebs. I’ve taken these recommendations, added some others, and tested extensively. Here is my new set of recommendations for MMDVM duplex hotspot reliability when using DMR. This supersedes my article from August 29, 2019.

1) Update to the latest firmware.
2) Run the MMDVMcal procedure to minimize the BER
3) Set the MMDVMHost modem TXDelay=50
4) Set the MMDVMHost modem DMRTXLevel=55
5) Set the MMDVMHost DMR TXHang = 20
6) Turn off any mode other than DMR to avoid protocol scanning negotiation
   issues.

I withdraw my earlier recommendation to reduce the DMR preamble. After much consideration, it seems to be unnecessary, with no clear benefit.

So far, using these setting on 2 different N5BOC duplex hotspots have yielded excellent results and reliability. Negotiation failures are now the rare exception. Tests were conducted with an Alinco DJ-MD5, a TYT MD-380, a CS-700 and a Hytera PD-365. Give these settings a try and let me know how they work for you.

73 de K2IE

X10 Firecracker

Does anyone still make use of X10 powerline control devices? X10 has been largely replaced by more modern wifi based home automation devices, but I still have a few that control lighting.

I recently upgraded my main home/office server to Fedora 32. Fedora dropped python2 from new systems because python2 will be considered obsolete by the end of 2020. I have a serial based device called the X10 Firecracker which I use for wireless on/off control. The Firecracker is controlled by a python script run via crond, the system scheduler.

The script was written long ago by someone else in python2. While doing a post-upgrade checkout, I found that the firecracker.py script no longer functioned because I no longer had python2 installed on my system. So, it was time to port it to python3.

Fortunately, the porting effort was trivial. I have shared the results in my Github repository in case anyone else needs it. And if you’re still running any critical functions using python2 it is time to port them to python3.