Archive for the ‘Uncategorized’ Category

The CommRadio CTX-10 vs. Elecraft KX2, SDRplay RSPdx, and the AM band gold rush of 1920

Stories you’ll find in our February, 2020 issue:

A Tale of Two Radios: CommRadio CTX-10 vs. Elecraft KX2
By Thomas Witherspoon K4SWL

A longtime ham and shortwave listener who enjoys taking his hobby into the field, Thomas was intrigued by two seemingly different transceivers that also appeared to have a lot in common. Which would be better for his purposes and why? Both offer low-power and battery-operated portability, but with a totally different design approach. Thomas examines the pros and cons of the CommRadio CTX-10 and the Elecraft KX2, not the least of which in the monetary component.

TSM Reviews: SDRplay RSPdx Software Defined Radio
By Larry Van Horn N5FPW

SDRplay Limited is a UK-based company that has been developing cutting-edge software defined radios since 2014 with its RSP1 model. In the ensuing years, newer models have offered advanced reception features on receivers capable of tuning from 1 kHz to 2 GHz at moderate price levels. In this review Larry takes a look at the company’s latest product, the SDRplay RSPdx and compares it with lower level SDRplay editions.

Radio in the Pre-Broadcast Era Series:
The Trailblazers of Commercial Radio Manufacturing in the 1920s
By Richard Fisher KI6SN

Beneath the dust accumulated over 100 years of consumer-entertainment radio broadcasting are the names of literally hundreds of manufacturers who have largely disappeared since the AM band gold rush of 1920. Richard takes a look at the radios available 100 years ago and finds a long list of names that urgently filled a huge void in practical receivers that could capture the signals of the handful of commercial broadcast stations that burst onto the airwaves early in the second decade of the 20th Century.

TSM Annual Review of Books for Shortwave Listeners
Klingenfuss 2020 Shortwave Frequency Guide
Reviewed by Bob Grove W8JHD

Joerg Klingenfuss never disappoints serious shortwave listeners with his exhaustive databases, and these two latest releases are no exception.

2020 World Radio Television Handbook
Reviewed by Gayle Van Horn W4GVH

The 74th edition of World Radio TV Handbook continues to be a comprehensive reference book. It remains the gold standard as the most authoritative for a global radio and television audience and the gem of the broadcast industry.

Global Radio Guide
Reviewed by Ken Reitz KS4ZR

The Winter 2019-20 edition of the Global Radio Guide, now 500 pages, includes many full length articles on shortwave listening today, but the best part is the Global Radio Frequency Guide that makes tuning in to signals from around the globe faster and easier than ever.

Scanning America
By Dan Veeneman
Nassau County, New York and TIS Stations

Federal Wavelengths
By Chris Parris
Federal Monitoring Mysteries

Milcom
By Larry Van Horn N5FPW
Monitoring the Australian Wildfires

Utility Planet
By Hugh Stegman
HF Steps Up in Australian Fire Emergency

Shortwave Utility Logs
Compiled by Mike Chace-Ortiz and Hugh Stegman

VHF and Above
By Joe Lynch N6CL
Morphing the Planned Hexagon-type Antenna into a 2-Element Quad

Digitally Speaking
By Cory Sickles WA3UVV
DV: How Low Can You Go?

Amateur Radio Insights
By Kirk Kleinschmidt NT0Z
Floods, Pestilence and Interference?

Radio 101
By Ken Reitz KS4ZR
2020 DRM Shortwave Report: Trials and Tribulations

World of Shortwave Listening
By Andrew Yoder
MW/SW Pirates; Carrier Sleuth and SWL Fest 2020

The Shortwave Listener
By Fred Waterer
Vatican Radio; BBC and WBCQ

Amateur Radio Astronomy
By Stan Nelson KB5VL
Geminids 2019 and Quadrantids 2020

Adventures in Radio Restoration
By Rich Post KB8TAD
The Reflex: Crosley Trirdyn Special

Antenna Connections
By Dan Farber AC0LW

The Spectrum Monitor is available in PDF format which can be read on any desktop, laptop, iPad®, Kindle® Fire, or other device capable of opening a PDF file. Annual subscription is $24. Individual monthly issues are available for $3 each.

LHS Episode #320: The Fire Down Below

Welcome to the 320th installment of Linux in the Ham Shack. In this episode, the hosts cover amateur radio and the recent earthquake in Puerto Rico and fires in Australia, Bitcoin, ARRL awards, Huawei, TensorFlow, Tucnak, Gridtracker and a whole lot more. Thank you for listening to our program and we hope you have a fantastic week.

73 de The LHS Crew

Smoke & Solder Host to Kick-Off Banner Year of CMSARA Speakers

January 11, 2020. (Brandon, MS): For Immediate Release

Information Contact: Frank Howell K4FMH [email protected]

A fan favorite from the internationally known video podcast, Ham Nation, kicks off the 2020 programs for the Central Mississippi Amateur Radio Club. “We are delighted to have George Thomas W5JDX, star of the Solder Smoke segment on Ham Nation and founder of AmateurLogic.tv, give our first presentation on January 14, 2020,” said Frank Howell K4FMH, Vice President for Programming. Ham Nation Founder Bob Heil K9EID says that Smoke & Solder is by far the most popular segment of the show according to email and other feedback. George’s topic will be, “DIY Projects Using Arduino and Raspberry Pi,” beginning at 7:00pm at the Rankin County Extension Service and EOC Building. CMSARA President Quinton Frasier KW5TON added, “I’m excited to see George W5JDX in person this month at our meeting. It’s unusual that we could get him to give a live talk since he’s so busy with Ham Nation, Amateur Logic TV, and his day job of RF Engineer for many radio stations in the Central Mississippi area.”

George W5JDX is only the first well known ham to headline this year’s program agenda, added Frank K4FMH. “We will follow George with the prolific author, broadcaster, and ham radio operator Don Keith N4KC in February.” Don’s recent book, Firing Point, was made into a very popular movie, Hunter Killer, with others on the way. He is a prolific author of books about shortwave and amateur radio, one of which is The Amateur Radio Dictionary: The Most Complete Glossary of Ham Radio Terms Ever Compiled. Don’s February presentation via Skype will be on Ham Radio Lingo. Our year will backend with Rob Sherwood NC0B, producer of the Holy Grail of receiver measurement ratings, the Sherwood Tables. Rob’s talk, also via Skype, is titled, “How to Use My Tables.” These are very well-known amateur radio operators but we have much more during the year planned for presentations.

“We wanted to blend some well-known ham speakers that we do not regularly get to experience in a club setting with informative topics from both our own members and other area hams,” Frank K4FMH said. “I think we’ve done that.” Topics and speakers include operations on six meters (Mike Duke K5XU), WSPR (J.D. Toony K5HH), APRS (Mike McKay APRS), and digital modes on HF (Eddie Pettis N5JGK and Carolyn Irons KJ5RC). We will also cover preparing for contest operations (John Struemph  K1JHS), establishing basic test equipment on your workbench (Tom Brown AE5I) and a festival of pictures of CMSARA member shacks during a program called Shack Night!. Frank K4FMH said, “I’m very pleased to have area hams who are affiliated with the Jackson ARC and the Vicksburg ARC to deliver top flight presentations to our membership and meeting attendees.” The ability to have an interchange of ideas and experiences from area hams is a real benefit to maintaining a vibrant club.

CMSARA welcomes non-members, hams who are visiting the area, and groups from nearby cities to join us at the Rankin County Extension Service auditorium where we have plenty of seating, good audio-visual equipment, and Internet access. We keep the “business” end of our club to a minimum and include a half-hour of pre-program fellowship as well as after the program itself. VE Testing is available every month with the exceptions of June and December due to Field Day planning and our Christmas Party respectively. The club has periodically had car pools of hams from as far away as the Starkville and Columbus areas attend CMSARA programs.

J.D. Toony K5HH, Vice President of Special Events added, “This will be an exciting year for radio amateurs in the Central Mississippi area. Not only for this month program agenda but for the multiple outings we are planning, a group Field Day, our new involvement with the Girl Scouts program, and a new repeater Net for new hams.” CMSARA welcomes visitors so get a car pool together and come visit us! Our website at http://centralmsham.club has updated information as well as via our Facebook group (https://www.facebook.com/groups/CMSARA/), e-mail ([email protected]) and telephone (601-345-1654).The Central Mississippi Amateur Radio Association is a non-profit 501(c)(3) status Mississippi  corporation serving counties in the Central Mississippi area. We focus on promoting having fun within the hobby and serving our communities through emergency and public service communications. We meet monthly on the second Tuesday at the Rankin County Extension Service / EOC Building, 601 Marquette Road, Brandon, MS 39042. Contact us at 601-345-1654 or at [email protected] for additional information. Any program changes will be communicated via the club website and Facebook page.

“BEST REGARDSES” AND “BEST REGARDS’S”

Meme: Car and Woman Arguing, 73

Meme: Car and Woman Arguing, 73

“Best regardses” and “Best regards’s”

That’s silly, of course. We who speak and write in the English language know that you should not pluralize a word that is already in its plural form. “Best regards” means, “I wish you the best of regards.” It is implied that there is more than one regard. Perhaps there are a few, perhaps many more. It then is clear that we wouldn’t normally pluralize “regards,” into, “regardses.”

It is also silly to say that the best of regards owns something.  How can a regard let alone a group of regards own anything?  So, why “73’s” when written?

Old SWLer QSL Card With 73's

Old SWLer QSL Card With 73’s

The usage of “73” comes from early landline telegraph (typically railroad telegraphy landlines). Originally devised in the era of telegraphs, 73 and other numbers were used to speed up the transmission of common messages over landlines by mapping common messages to these specific numbers.  And, numbers were quicker to send than the longer messages the numbers replaced.

QST, April 1935, on page 60, contains a short article on the origin of the amateur radio vernacular, 73. This article was a summation of another article that appeared in the “December Bulletin from the Navy Department Office of the Chief of Naval Operations,” published December of 1934.

Landline (Railroad) Morse Code

A skilled landline Morse code operator, in action.

Here’s a quotation from that Navy article:

“It appears from a research of telegraph histories that in 1859 the [land-line] telegraph people held a convention, and one of its features was a discussion as to the saving of ‘line time.’

A committee was appointed to devise a code to reduce standard expressions to symbols or figures. This committee worked out a figure code, from figure 1 to 92.

Most of these figure symbols became obsolescent, but a few remain to this date, such as 4, which means “Where shall I go ahead?’. Figure 9 means ‘wire,’ the wire chief being on the wire and that everyone should close their keys. Symbol 13 means ‘I don’t understand’; 22 is ‘love and a kiss’; 30 means ‘good night’ or ‘the end.’

The symbol most often used now is 73, which means ‘my compliments’ and 92 is for the word ‘deliver.’ The other figures in between the forgoing have fallen into almost complete disuse.”

We can see, then, that “73” mapped to “best regards” or “my compliments” and was intended as a general valediction for transmitted messages.  That’s why it is silly to say, “73s,” as that maps to, “best regardses” – 73s adds the plural to a plural.  (And, don’t make it possessive, as in using, “73’s” – a regard cannot own something).

Jeeves, there's no plural for 73

Cartoon: Jeeves, there is no plural for 73…

For reference and some more interesting background on this, see http://www.signalharbor.com/73.html

An example of on-the-air conversation (or, QSO—“QSO” is the shorthand Q-code for, “two-way exchange of communications”) illustrates proper usage of 73. When saying your goodbye, you would tap out the Morse code as follows:

TNX FER FB QSO. C U AGN. 73 ES HPY NEW YR.

That is interpreted as, “Thanks for the fine-business chat. I hope to see you again for another chat. Best regards and happy new year.”

This, if you choose to throw around shorthand Morse code number codes when you are speaking, you wouldn’t say, “73s.” You would say, “73.”

Old Man Hiram Percy Maxim 1AW QSL Card with 73's

The Old Man Hiram Percy Maxim 1AW used 73’s on his QSL cards.

My friend, David Edenfield, opined, “This idea is beyond turning into glue from the dead horse it’s beating again. This is so petty to be concerned with this. Even the Old Man Hiram Percy Maxim 1AW used 73s on his QSL cards.”

Well, even Hiram Percy Maxim has been incorrect and incorrectly used grammar. (chuckle)

There is something to be said about teaching new amateur radio operators the best of our traditions, history, skills, procedures, protocols, ethics, and culture. There’s no rational argument that can make a case that allowing these aspects of our service and hobby to degrade over time (by the lack of Elmering) is a good way to see our service and hobby thrive and progress.

I don’t see any slippage from high standards as being a good strategy for nurturing growth, progress, and effectiveness of our service and hobby. Keeping some level of excellence in every aspect of our hobby can only be beneficial.

In this case, how many new hams that learn to repeat ham lingo know anything of the history behind the common “73?” My dead horse turned glue is educational and it is my belief that educating about origins elevates the current.

73 – NW7US

NW7US QSL Card (circa 2019)

NW7US QSL Card (circa 2019)

..

 

Post UK Election TX Factor is Live!

Nothing to do with the election, or Brexit – you’ll be pleased to hear! TX Factor episode 25 is now live at www.txfactor.co.uk. We look at more new and innovative AR products from this year’s UK Hamfest, including a potted history of the ever-popular and much revered range of transceivers and kits from Electraft with co-founder Eric Swartz WA6HHQ.

In this modern era of connectivity, we take the ever-present Internet for granted; it’s always there and continues to deliver our data from A to B without issue. But what would happen if that vital link failed? We visit Southampton and Portsmouth on the UK’s south coast to see how two city councils, assisted by a group of dedicated amateurs, plan to maintain their communications infrastructure via radio links alone, should the Internet go down.

Wishing you a Happy Christmas and a radio active New year from all at TX Factor.

Regulated power supplies, sunspot cycles, ham radio satellites and more

Stories you’ll find in our December, 2019 issue:

Before Radio’s First Century: “Pre-Broadcasting” Activity in North America
By John Schneider W9FGH

For many decades, the prevailing myth has been that broadcasting in the United States first occurred on the night of November 2, 1920. According to this general conviction, no broadcasting took place anywhere before that date, but then, in a brilliant stroke of genius, it was suddenly invented that night by the Westinghouse Corporation when its new station, KDKA, broadcast the Harding-Cox election returns. Nothing could be farther from the truth! By 1920, experimental broadcasting had already been happening around the US for many years. John takes a look at the country’s transition from that early experimentation to formal broadcasting.

Radio’s Role During Pearl Harbor’s ‘Day of Infamy’
By Scott A. Caldwell

Diplomatic relations between the United States and the Japanese Empire had steadily deteriorated in the years that followed the First World War. On May 7, 1940 the US Navy Fleet reluctantly relocated its operating headquarters from San Pedro, California to Pearl Harbor, Hawaii. President Franklin D. Roosevelt considered the redeployment as vital because it represented a significant military deterrent to the growing Japanese bellicosity. However, there was great concern and opposition to this action that was headed by Admiral James O. Richardson, Commander-in-Chief US Fleet, who believed that they would be unnecessarily exposed to attack from the Japanese Navy. Seven months later a price would be paid.

Those Regulated Power Supplies from Heathkit and Others
By Rich Post KB8TAD

In recent columns on testing and restoring the National SW-3, FB-7 and the HRO Senior, Rich initially used metered regulated power supplies in place of the matching “doghouse” power supplies to keep those vintage National supplies from possible overloads and damage before full restoration of the receivers. In his previous column on the HRO, he mentioned replacing the entire HRO power pack with a totally voltage-regulated supply since varying the RF gain control changed the set’s current draw somewhat and thus the B+ on both the oscillator and the mixer. As promised, he takes a second look at that supply.

Novice-era Hamming Today: Still a Thrill
By Cory GB Sickles WA3UVV

Cory’s first amateur radio station consisted of a solid-state Realistic (Radio Shack) DX-150A general coverage receiver and a gently used Heathkit DX-20 transmitter, that incorporated three tubes to produce 20 Watts out. He used a set of house switches in a metal box to swap the antenna between the receiver and transmitter, plus mute the receiver when transmitting. It was not the best solution, but it was cheap, and it worked. If you, like Cory, have a hankering to revisit your old Novice operator days, it can still be done—with vintage gear or even their modern equivalent. Cory explains how you can start your own Novice-era memories.

Scanning America
By Dan Veeneman
Tillamook County, Oregon; Vintage Scanner Crystals

Federal Wavelengths
By Chris Parris
Scanning Projects

Milcom
By Larry Van Horn N5FPW
Monitoring the DoD High Frequency Global Communications System

Utility Planet
By Hugh Stegman
HF Utility in Troubled Ukraine

Shortwave Utility Logs
By Mike Chace-Ortiz and Hugh Stegman

VHF and Above
By Joe Lynch N6CL
Planet Alignment and Sunspot Cycles Linked?

Digital Voice
By Cory GB Sickles WA3UVV
Three Short Subjects for New Hams

Amateur Radio Insights
By Kirk Kleinschmidt NT0Z
A Log-Periodic Tragedy

Radio 101
By Ken Reitz KS4ZR
Free-to-Air Satellite TV Update

Radio Propagation
By Tomas Hood NW7US
Largest Sunspot in Solar Sunspot Cycle 24

The World of Shortwave Listening
By Rob Wagner VK3BVW
Online SDRs: Impacting the Way We Listen to Shortwave

The Shortwave Listener
By Fred Waterer
Shortwave Listening Past and Present

Amateur Radio Satellites
By Keith Baker KB1SF/VA3KSF
Amateur Radio Satellite Primer (Part VI)

The Longwave Zone
By Kevin O’Hern Carey N2AFX
LF Info: 101

Adventures in Radio Restorations
By Rich Post KB8TAD
Helping Dan: A Silvertone 6230A Farm Set

Antenna Connections
By Dan Farber
Feedlines: Getting There from Here

The Spectrum Monitor is available in PDF format which can be read on any desktop, laptop, iPad®, Kindle® Fire, or other device capable of opening a PDF file. Annual subscription is $24. Individual monthly issues are available for $3 each.

From Lightning Comes a New Icom IC-7610 (First Transmission)

Wow. What a radio!

One of the most useful (and, to me, amazing) features of this Icom IC-7610, is the IP+ function, which, when turned on, improves the Intermodulation Distortion (IMD) quality by optimizing the direct sampling system performance. This function optimizes the Analog/Digital Converter(ADC) against distortion when you receive a strong input signal. It also improves the Third-order Intercept Point (IP3) while minimizing the reduction of the receiver sensitivity.

In short: I was listening to an s-0 (i.e., no strength-meter movement) weak signal of a DX station, when right adjacent to the frequency came an s-7 signal, wiping out my ability to copy that weak signal. I turned on the IP+ and the distortion of the adjacent signal disappeared, and once again, I heard the weak signal IN THE CLEAR! WOW!

This video is a quick capture of my running the Olivia Digital Mode on HF, on the 30-Meter band. The transmissions are of a two-way Olivia digital-mode radio conversation between station K8CJM and station NW7US on 12 November 2019 (UTC date). K8CJM is located in Dayton, Ohio, and I am located in Lincoln, Nebraska. I’m running the radio at full power. The radio is rated as being able to handle 100% duty cycle at full power. The radio ran cool, no significant heating.

A few months ago, a lightning strike took out my ham radio station. The antenna was NOT connected, but I did not unplug the power supply chain and my computer from the wall. The surge came in through the power mains, and fried my uninterruptable power supply, the interfaces between my PC and radio, and fried the radio. Thankfully, all of that was covered by my homeowner’s insurance policy, less the steep deductible. My insurance covered all of the blown items, and that provided me this chance to obtain a repack version of the Icom IC-7610. I bought an extended four-year warranty.

CAUTION: Check the documentation of your transceiver/transmitter. NEVER run your radio’s power out at a level that exceeds what it can handle in reference to the duty cycle of the mode you are using. Olivia, for instance, is a 100-percent duty cycle mode. Morse code is NOT quite 100% duty cycle. Nor is SSB, a mode that operates with a duty cycle much lower than 100%. Your radio’s manual should tell you the specifications regarding the duty cycle it can handle! If you run more power than your radio can handle with the given duty cycle of the mode in use, you will blow your radio’s finals or in some other way damage the radio! Beware! I’ve warned you!

Compression and ALC!?

Some have noted that it appears that I’ve left on the Compression of the transmitted audio. However, the truth is that compression was not being used (as is proof by carefully taking note of the zero meter movement of the Compression activity). I had the radio set for 20-Meter USB operation on the Sub VFO. Compression was set for standard USB operation. Note also that the radio was transmitting USB-D1, which means the first data/soundcard input to the radio.

Also, some people complain about my use of ALC, because, in their view, ALC (automatic level control) is a no-no for data modes.

The notion that one must NEVER use ALC when transmitting digital modes is not accurate.

Multi-frequency shift keyed (MFSK) modes with low symbol rate–such as the Olivia digital modes–use a single carrier of constant amplitude, which is stepped (between 4, 8, 16 or 32 tone frequencies respectively) in a constant phase manner. As a result, no unwanted sidebands are generated, and no special amplifier (including a transmitter’s final stage) linearity requirements are necessary.

Whether the use of ALC matters or not depends on the transmitted digital mode.

For example, FSK (Frequency-Shift Keying; i.e., RTTY) is a constant-amplitude mode (frequency shift only). In such a case, the use of ALC will NOT distort the signal waveform.

PSK31 does contain amplitude shifts, as an example, therefore you don’t want any ALC action that could result in distortion of the amplitude changes in the waveform.

On the other hand, the WSJT manual says that its output is a constant-amplitude signal, meaning that good linearity is not necessary. In that case, the use of ALC will NOT distort the transmitted signal-amplitude waveform. You can use ALC or not, as you choose when you run WSJT modes, or Olivia (MFSK).

Clarification

Nowhere in this am I advocating running your audio really high, thinking that the ALC will take care of it. I am not saying that. I am saying that some ALC is not going to be an issue. You MUST not overdrive any part of the audio chain going into the transmitter!

Transmit audio out of the sound card remains at a constant amplitude, so there will be no significant change in power output if you adjust your input into the radio so that the ALC just stops moving the meter, or, you can have some ALC meter movement. You can adjust your audio to the transmitter either way.

If the transmitter filters have a significant degree of ripple in the passband then you may find that RF power output changes with the selected frequency in the waterfall when there is no ALC action. Allowing some ALC action can permit the ALC to act as an automatic gain adjustment to keep the output power level as you change frequencies.

Linear and Non-Linear

Regarding linear and non-linear operation (amplifiers, final stages): While a Class-C amplifier circuit has far higher efficiency than a linear circuit, a Class-C amplifier is not linear and is only suitable for the amplification of constant-envelope signals. Such signals include FM, FSK, MFSK, and CW (Morse code).

If Joe Taylor’s various modes (in WSJT software) are constant-envelope signals, than class-C works, right? At least, in theory.

Some Additional Cool History

The digital mode, Thor, came out of DominoEX when FEC was added. Here is an interesting history of FSQ that seems to confirm that FSQ is like MFSK, so no problem with a bit of ALC.

The following is from https://www.qsl.net/zl1bpu/MFSK/FSQweb.htm

History – Let’s review the general history of Amateur MFSK modes. The first Amateur MFSK mode developed anywhere was MFSK16, specified by Murray Greenman ZL1BPU, then first developed and coded by Nino Porcino IZ8BLY in 1999. Before MFSK16 arrived, long-distance (DX) QSOs using digital modes were very unreliable: reliant, as they were, on RTTY and later PSK31. MFSK16 changed all that, using 16 tones and strong error correction. Great for long path DX, but nobody could ever say it was easy to use, never mind slick (quick and agile)!

Over the next few years, many MFSK modes appeared, in fact too many! Most of these were aimed at improving performance on bands with QRM. Most used very strong error correction, some types a poor match for MFSK, and these were very clumsy in QSO, because of long delays.

The next major development, aimed at easy QSOs with a slick turnaround, was DominoEX, designed by Murray Greenman ZL1BPU and coded by Con Wassilieff ZL2AFP, which was released in 2009. Rather than using error correction as a brute-force approach, DominoEX was based on sound research and achieved its performance through carefully crafted modulation techniques that required no error correction. The result was a simpler, easier to tune, easily identified mode with a fast turn-around.

DominoEX is widely used and available in many software packages. A later development by Patrick F6CTE and then Dave W1HKJ added FEC to this mode (THOR) but did not add greatly to performance, and at the same time eroded the fast turn-around. The final DominoEX- related development was EXChat, a version of DominoEX designed specifically for text-message style chatting. While completely compatible with DominoEx, it operates in ‘Sentence Mode’, sending each short over when the operator presses ENTER. EXChat was developed by Con ZL2AFP and released in 2014.

Back in 2013, Con ZL2AFP developed an MFSK mode for LF and MF which used an unusual decoding method pioneered by Alberto I2PHD: a ‘syncless’ decoder, which used a voting system to decide when one tone finished and another began. The first use of this idea was in JASON (2002), which proved to be very sensitive, but very slow, partly because it was based on the ASCII alphabet. The new mode, WSQ2 (Weak Signal QSO, 2 baud) combined the syncless decoder with more tones, 33 in total, and an alphabet specially developed by Murray ZL1BPU, which could send each lower case letter (and common punctuation) in just one symbol, resulting in a very sensitive (-30 dB SNR) mode with a 5 WPM typing speed.

In the subsequent discussion in late 2014, between the developers ZL2AFP and ZL1BPU, it was realized that if the computer had enough processing power to handle it, WSQ2 could be ‘sped up’ to become a useful HF chat mode. This required a large amount of development and retuning of the software to achieve adequate speed was involved, along with much ionospheric simulator and on-air testing used to select the most appropriate parameters.

Tests proved that the idea not only worked well, but it also had marked advantages over existing HF MFSK modes, even DominoEX. As expected, the new mode was found to have superior tolerance of signal timing variation, typically caused by multi-path reception, and would also receive with no change of settings over a wide range of signaling speeds.

So this is how FSQ came about. It uses the highly efficient WSQ character alphabet, IFK+ coding, the same number of tones as WSQ (33), but runs a whole lot faster, up to 60 WPM, and uses different tone spacing. The symbol rate (signaling speed) is modest (six tones per second or less), but each individual tone transmitted carries a surprising amount of information, resulting in a high text transmission speed. And it operates in ‘Chat’ (sentence) mode, which allows the user to type as fast as possible since they type only while receiving.

The ability to send messages and commands selectively has opened a huge array of communications possibilities.

What Makes FSQ Different

Incremental Keying – FSQ uses Offset Incremental Frequency Keying (IFK+), a type of differential Multi-Frequency Shift Keying (MFSK) with properties that make it moderately drift-proof and easy to tune. IFK+ also has excellent tolerance of multi-path reception.

IFK was developed by Steve Olney VK2XV. IFK+ (with code rotation) was proposed by Murray Greenman ZL1BPU and first used in DominoEX. IFK+ prevents repeated same tones without complex coding and provides improved rejection of propagation-related inter-symbol interference. In the context of sync-less decoding, the IFK+ code rotation also prevents repeated identical tones, which could not have been detected by this method.

Efficient Alphabet – In FSQ, a relatively high typing speed at a modest baud rate comes about because the alphabet coding is very efficient. All lower case letters and the most common punctuation can be sent in just one symbol and all other characters (the total alphabet contains 104 characters) in just two symbols. (The alphabet is listed below). This is a simple example of a Varicode, where it takes less time to send the more common characters. The character rate is close to six per second (60 WPM), the same as RTTY, but at only 1/8th of the baud rate. (RTTY has only one bit of information per symbol, 7.5 symbols per character, and wastes a third of its information on synchronization, and despite this, works poorly on HF).

No Sync – Another important factor in the design of FSQ is that no synchronizing process is required to locate and decode the received characters. Lack of sync means that reception is much less influenced by propagation timing changes that affect almost all other modes since timing is quite unimportant to FSQ; it almost completely eliminates impulse noise disruption, and it also contributes to very fast acquisition of the signal (decoding reliably within one symbol of the start of reception). Fast acquisition removes the need for the addition of extra idle characters at the start of transmission, and this leads to a very slick system. Add high resistance to QRM and QRN, thanks to the low baud rate, and you have a system so robust that it does not need error correction.

Cool.

See you on the bands!


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