The FCC will be voting on and will likely approve a Report and Order that eliminates the symbol rate restriction on HF data transmissions, replacing it with a bandwidth limit of 2.8 kHz. See FCC To Vote on Removing Symbol Rate Restrictions. The symbol rate limit of 300-baud is an obsolete way of limiting the signal bandwidth, created back when the data transmissions were predominately Frequency Shift Keying (FSK). It was a simple, practical way to regulate the bandwidth at that time but technology has moved on. The use of digital signal processing and efficient wireless encoding techniques require a better approach to bandwidth regulation.

A practical impact of this change is to allow higher speed protocols such as PACTOR-4 having a bandwidth of 2.4 kHz. I suspect we will see other protocols emerge that squeeze the best data rate out of the 2.8 kHz bandwidth.

Living in a Narrowband World

The FCC proposal implements a 2.8 kHz bandwidth limit on data emissions on the HF bands. Some folks have suggested a narrower bandwidth while others argue that wider bandwidth signals should be allowed. And some even think we should have no bandwidth limit at all.

The problem is that the amateur HF bands are not very wide. For example, the popular 20m band is 14.0 to 14.350 MHz, providing only 350 kHz of spectrum. Common practice on this and the other HF bands is to use modulation types that have bandwidths of 3 kHz or less. (Yeah, AM signals are twice that wide, at 6 KHz, a topic for another day.) Of course, CW and some of the data modes are much narrower than 3 kHz. But the general approach to regulating HF is to allow many narrowband signals on the band. Limiting HF data transmissions to 2.8 kHz bandwidth is consistent with existing practice while still allowing for innovation and experimentation.

VHF/UHF Bandwidth Limits

The FCC also plans to issue a Further Notice of Proposed Rulemaking (FNPR) that:

• Proposes to remove the baud rate limitation in the 2200 meter and 630 meter bands, which the Commission allocated for amateur radio use after it released the Notice of Proposed Rulemaking in 2016.
• Proposes to remove the baud rate limitation in the VHF and UHF bands.
• Seeks comment on the appropriate bandwidth limitation for the 2200 meter band, the 630 meter band, and the VHF/UHF bands.

I won’t comment on the 2200 meter and 630 meter bands. The FCC proposes to remove the symbol rate limit on the VHF and UHF bands and asks what bandwidth limit is appropriate. The current bandwidth limits are 20 kHz for the 6m and 2m bands, 100 kHz for the 1.25m and 70 cm bands, and the FCC seems fine leaving these the same. Authorized emission types are listed in FCC Part 97.305.

With 4 MHz of spectrum, the 2m band is much wider than any of the HF bands. It might be tempting to conclude that there is plenty of room for wideband signals on this band. Many hams think 2 meters is just used for FM simplex and repeaters but a closer look reveals that it supports many diverse modes: weak-signal SSB/CW, meteor scatter, EME, FM simplex, FM repeaters, digital voice modes (D-STAR, DMR, Fusion), satellites, and more. The 20-kHz limit seems appropriate, as it roughly matches the bandwidth of the most common (FM) voice signals on that band. It is not an appropriate band for trying out wider bandwidth signals.

The 6m band should probably keep the same 20-kHz limit. (I don’t think there is a compelling reason to change it.) The 1.25m band already allows 100-kHz bandwidth data signals, which some radio amateurs have used for higher-speed data links (still not what I would call wideband).

The 70 cm band is much bigger (420 MHz to 450 MHz) and could accommodate some wider bandwidth signals. Perhaps the existing 100-kHz limit should be increased? Keep in mind that fast-scan ATV is allowed on this band with a bandwidth of 6 MHz. Maybe we can make some room for a few larger bandwidth data channels, to encourage innovation and experimentation.

The bands above 70 cm have no bandwidth limit other than the signal must stay within the designated ham band. It has been this way for a long time, without causing any issues (that I know of).

Conclusion

The FCC’s proposal makes a lot of sense and it is long overdue. Frankly, it is a bit of an embarrassment that it has taken so long.

Better late than never.

73 Bob K0NR

The post Adios Symbol Rate Limit appeared first on The KØNR Radio Site.

This is the most difficult article I’ve ever had to write, not only because I lost a very good friend, but also because it’s so hard for me to put into words and express the impact this person had on my life and others.

I met Rob about 25 years ago. Rob lived in Philly working long hours programming minicomputers. He developed various medical issues and had to retire early, relocating to the Poconos here in Pennsylvania. He tended to be a night owl, sleeping all day and relentlessly pursuing amateur radio projects at night. We served at our struggling local ham radio club for several years, me as president, him as vice president. He joked his callsign should be VP4LIFE. Rob was a ever-present friendly voice on the local 2 meter repeater, welcoming beginners and having conversations with other night owls well into the morning. We spent many a night at Field Day, operating the CW station and we both substantially improved our CW skills over the years.

Rob and I tended to be mentors to each other. We frequently had multi-week email conversations going about projects. Rob would get interested in a topic and he’d call or email me. Rob always seemed to know the right questions to ask. I would research the topic and inevitably get interested in it. We went down many technical rabbit holes over the years, some going nowhere, others resulting in some sort of rig, circuit, or antenna. I would often wake up in the morning to one or several 10,000+ word emails with pictures showing what Rob was experimenting with. Rob never bought a few components for a project, he’d buy 1,000 of each, and stockpile the unused parts in case he wanted to build more of something or give the parts away to others. Our last major conversation was about making vacuum tubes from scratch, with him collecting the necessary tooling and materials to do this. We complemented each other well, with Rob having the energy, curiosity, and ability to create the spark, and me with the technical know-how to figure things out and fan the spark to become a fire. I can honestly say I am a better radio amateur and person today because of Rob.

I’m still in shock over the loss of Rob. I often see some neat project and think that I should email Rob, but realize he’s no longer around. I open in my email in morning expecting to read a long diatribe about some late night experiments, but there is nothing there.

Robert Roomberg, KB3BYT, 63 years old, Silent Key. Dit dit.

This article was originally posted in Radio Artisan.

Ham College episode 106 is now available for download.

Extra Class Exam Questions – Part 44
E9B Antenna patterns and designs: E and H plane patterns, gain as a function of pattern,antenna modeling.

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Another month has zoomed by and it's CLE time once again. This is a challenge for all newcomers to NDB listening and the ultimate test of your medium frequency receiving capabilities. Can you meet the challenge?

From CLE organizers comes the following info:

Hello all

This weekend was the running of the Worked All Germany contests or WAG. This contest supports both CW and SSB within the same contest. As for me, it was strictly CW....go figure eh!. As happens now and then just before the contest there was an atmospheric burp and the K index moved to 5! The good thing about this is everyone is affected so your still kinda on the same playing field more or less. 

This is a 24-hour contest that starts at noon Saturday my time. With the poor solar conditions, there was lots of fading in and out (QSB). This resulted in lots of repeats and contacts that started at S7 and ended somewhere in the dust. I take this as an opportunity to sharpen my CW skills and learn more about the Icom 7610 filtering. This time around I took advantage of the two independent receivers the 7610 has. I had a split screen of the band I was on and the next band that could in time show some excitement. This came in very handy today when I noticed 10 meters coming to life. I swapped out 15m for 10m as it seemed to just jump to life. I had 51 contacts in just 1.5 hours and that was during so-so band conditions. I entered the contest as single operator/all band / low power (100 watts). It was a very rainy weekend here so that made it very easy to stay in the radio chair and plug along.

In this episode, we join Martin Butler M1MRB, Chris Howard (M0TCH), Martin Rothwell (M0SGL), Frank Howell (K4FMH), Bill Barnes (WC3B) and Leslie Butterfields (G0CIB) to discuss the latest Amateur / Ham Radio news. Colin Butler (M6BOY) rounds up the news in brief and in the episode's feature is The Importance of WRC Agenda 9.1B

We would like to thank our monthly and annual subscription donors for keeping the podcast advert free. To donate, please visit - http://www.icqpodcast.com/donate

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