AmateurRadio.com

Sure! You don’t need to have a software-defined radio (SDR) before you start learning how to use the technology; there are a few different paths you can take, exploring and learning about SDR.

One way to gain some experience with SDR without spending a dime is to install a free software package for the very popular, non-Linux, operating system (that starts with ‘W’), and give SDR a test drive. If you like it, you might consider getting your own hardware (like the SDRplay RSPdx, for instance), and connecting it up to your computer and running this software, too.

Why I Dived Into SDR

I have always loved radio, ever since the early 1970s, when I discovered shortwave radio. In the last couple of years, I’ve had an increasing interest in the world of SDR. When I am working, but away from home (remember those days, before Covid?), I want to sample news and programming from around the world, but through shortwave. The way to do that, I found, is by using the various SDR options which allow a person to tune a remote receiver, and listen.

I also find working with the waterfall of a typical SDR-software user interface rewarding because, instead of blindly searching for signals in a subband, I can see all of the received signals on the scrolling time representation of a slice of frequency. Simply select that signal on the waterfall, and the radio tunes right to it.

I often connect to different SDR radios around the world, to catch all manner of shortwave signals, from maritime, military air, trans-oceanic air, or coast guard radio traffic, or other interesting HF communications including amateur radio CW and SSB signals. Occasionally, I also check out VHF and UHF signals from around the world. All of that, while instead an office building that is not suited for shortwave radio reception.

I’ve now decided to give back to the community; I’ve added my SDR receiver to the collection of receivers located around the world on the SDRSpace network of SDR radios.

My new SDRplay RSPdx software-defined radio receiver is live, via http://www.sdrspace.com/Version-3, using the SDR Console software (Version 3).

The receivers are online whenever I am not transmitting and when there are no local thunderstorms.

Antenna Port A is connected to a wire antenna (a horizontal 100-foot wire that runs out from my house’s chimney to a tall tree; about 10 feet of that wire is oriented vertically, where the wire passes through a pulley and then is weighted down so it can move with wind-driven tree movement), while Antenna Port B is connected up to a VHF/UHF discone.

Both antenna systems have an AM Broadcast band notch (reject) filter reducing local AM Broadcast-Band radio station signals by about 30 to 40 dB. I need to use these because the very close KLIN transmitting tower is just miles away and those signals overwhelm the receiver. When I use the signal filters, the local AM Broadcasting signals no longer overwhelm the receiver.

In the following video, I first explain my SDR setup, and in the second half of the video, I tune around the radio spectrum, using the software to control my SDR receiver.

A Couple of Questions

After watching this video, WO9B wrote an email to me. Michael asked of me two questions, summed up as:

1. Your SDR window has the IF screen on top. How is that accomplished?

2. Your AM Broadcast filters; more info, please. I live in the area of mucho broadcast stations and that looks like something I could use.

In the following video, I demonstrate how I changed my layout of the SDR Console software. And, I mention the AM Broadcast Filter for SDR Receivers (the hardware filter is found here: https://g.nw7us.us/3kU5SJN).

To Use My Receiver

Download the latest version of SDR-Console from https://www.sdr-radio.com/download – there is a 32-bit and a 64-bit Windows installation package.

The 64-bit installation package may be downloaded from one of these three sources:

1. Google: https://g.nw7us.us/3auBq44
2. DropBox: https://g.nw7us.us/310ooIG
3. Microsoft: https://1drv.ms/u/s!AovWaZDu7Hrd3U-yqK1bs3wuaFw2?e=o4nKeh

The 32-bit installation package can be downloaded from one of these three sources:

1. Google: https://g.nw7us.us/3iLasrZ
2. DropBox: https://g.nw7us.us/3g4VcVc
3. Microsoft: https://1drv.ms/u/s!AovWaZDu7Hrd3U4mJiiRtI9lm70s?e=HDG4ZX

Install the SDR Console package according to the directions given. Once you have the software installed, you will want to add my server. It takes some work to get familiar with the software, but there are online FAQs on how to begin.

One guide on how to add a server to the list from which you can pick may be found, here:

https://www.sdrplay.com/wp-content/uploads/2018/02/SDRConsoleV3-ServerGuide1-1.pdf

I worked on getting all of the bugs worked out of my installation before making the video. It did take some work, and reading up on things. But, the software is solid and a good contender against SDRuno, and HDSDR, and, this way I can share it online with you.

My server is known as, ‘0 NW7US‘ — it will be online when I am not using my antenna systems for transmitting. It will be offline during thunderstorms, or during times when I must use the systems for transmitting.

Software-defined radio is a great way to hear all sorts of communications, from local AM broadcast stations, FM stations, VHF Air Traffic, to shortwave radio stations including amateur radio HF communications.

Thank you for watching, commenting, and most of all, for subscribing; please subscribe to my YouTube Channel: https://YouTube.com/NW7US Also, please click on the bell, to enable alerts so that when I post a new video, you will be notified. By subscribing, you will be kept in the loop for new videos and more.

73 de NW7US

.. (yes, this is an expansion of an earlier post… forgive the redundancy… thank you) ..

My new SDRplay RSPdx software-defined radio receiver is live, via http://www.sdrspace.com/Version-3, using the SDR Console software (Version 3).

The receivers are online whenever I am not transmitting and when there are no local thunderstorms.

Antenna Port A is a wire antenna (100′), while Antenna Port B is a VHF/UHF discone. Both have an AM Broadcast band reject filter, reducing local AM Broadcast signals by about 30 to 40 dB. I need to use these because the very close KLIN transmitting tower is just miles away and those signals overwhelm the receiver. When I use the signal filters, the local AM Broadcasting signals no longer overwhelm the receiver.

Let me know what you think. Enjoy!

To use my receiver:

Install the latest version of SDR-Console which can be downloaded from https://www.sdr-radio.com/download

Install SDR Console according to the directions given. Once you have the software installed, you will want to add my server.

It takes a little to get familiar with the software, but there are online FAQs on how to begin.

My server is known as, ‘0 NW7US‘ — it will be online when I am not using my antenna systems for transmitting. It will be offline during thunderstorms, or during times when I must use the systems for transmitting.

Software-defined radio is a great way to hear all sorts of communications, from local AM broadcast stations, FM stations, VHF Air Traffic, to shortwave radio stations including amateur radio HF communications.

Thank you for watching, commenting, and most of all, for subscribing; please subscribe to my YouTube Channel: https://YouTube.com/NW7US Also, please click on the bell, to enable alerts so that when I post a new video, you will be notified. By subscribing, you will be kept in the loop for new videos and more.

Video:

73!

This article is part two of the series taking a look at band plans and gentlemen agreements.
See part one, here: Land (er, FREQUENCY) Grab.  See part three, here: In Response — Can’t We All Just Get Along?

Displaced and Marginalized

There are some unhappy amateur radio operators in the world of shortwave operations. Users of Morse code, and digital modes other than the highly-popular modes engineered by Joe Taylor, K1JT, feel displaced on the many amateur radio bands where Joe’s wildly-popular mode FT8 has erupted.

Joe (born March 29, 1941), is a friend of hams everywhere, and is an American astrophysicist and Nobel Prize in Physics laureate (https://g.nw7us.us/2Ptquv1) for his discovery with Russell Alan Hulse of a “new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation.”

Many have asked questions like, “Did Joe Taylor K1JT Destroy Amateur Radio? Did Joe Taylor K1JT, Nobel Laureate and noted friend of hams everywhere, accidentally destroy amateur radio?” This question remains relevant, even as more and more FT8 operators take to the HF bands to chase wallpaper and awards.

FT8 Has Validity and Usefulness

Full disclosure: I administer a Facebook group for FT8 and FT8-related modes, because I believe that the mode has a valid place in our amateur radio technology portfolio.  Here is the Facebook group URL, if you would like to join the fun: https://www.facebook.com/groups/FT8.FT4.HF.6m/. Understand, I have used and will continue to use FT8.

Because it has a place, it stands to reason that everyone should become more aware of the impact of using FT8 on the bands. It also stands to reason that it should be used ethically, and in the best spirit of amateur radio.

Many amateur operators use the FT8 digital mode as a novelty when there isn’t much else happening on amateur radio shortwave bands. One of the great things about it is that you can tell when a band is open–even though you don’t hear any other signals of other modes on the band in question, you very well may hear the roar of FT8 on the band where propagation actually exists to somewhere else than your QTH.

Others use it to finally get their DXCC, or WAS, or other award and wallpaper. This is especially popular during this season of the sunspot cycle where there are no sunspots–propagation is limited to lower-HF amateur bands because there’s just not enough solar activity to energize the ionosphere enough to open up the higher segment of shortwave.

FT8 Has Limitations

Can FT8 be used for two-way conversations? No. However, the JS8CALL digital mode is designed from the FT8 mode, by changing the protocol in a way that allows free text. It is designed for ragchewing and the new version 2.0 offers three modes of chat with 50 Hz and 16 wpm, 80 Hz and 24 wpm, and the turbo mode at 160hz and 40wpm with turbo only having a 6-second turn around time. The designated frequency is 7.078, which many find much nicer to use.

However, many find JS8CALL combersome, and non-intuitive.  How fast and how reliably can it handle critical messages, say, during an emergency?  I’m sure the software will improve, but how good is the protocol?

A mode such as Olivia has been field proven, and time tested.  It can reliably handle traffic.

The Rant

During the early days of widespread FT8 operation that came with the first public non-Beta release of FT8-equipped WSJT-X software, I tried to reason with the FT8 development leadership team. I made a polite attempt at explaining how incredibly rude they were in purposefully programming into the software the default operating frequencies such as 7.075, 14.075, and so on.

One of the main leaders of that team slammed me and stated that “we only suggested those frequencies; the operator is free to change them.” Additionally, he stated that the team used a common QSO/Mode spotting website to see what digital modes or other operations (like CW) were sparser. They perceived that the frequencies they proposed where no longer active because they saw few if any spots. They thought that no one would care.

I explained that a single website-spotting strategy was illogical and very lazy. This is true for several reasons, at least.

I guess you have to have a Ph.D. to know better than any average ham who went by gentleman’s agreements. I have an extremely dim view of JT and his disciples. CW is not the only operating group he’s engineered out of traditional slices of spectrum. Olivia, and other modes, now have been pushed down into PSK subbands, and everyone is feeling the crowding. As far as my thinking of FT8, well, it is radio, but it doesn’t foster goodwill and building serious communications skill. IMHO.

Play Nice, Be Positive and Polite. Smile.

I’ve received wise counsel from a number of fellow amateur radio operators.  They implore us to not promote hostility between “us and them.”  That even though the WSJT team is playing the playground bully, we should not be vengeful, but polite and willing to negotiate in good faith.

If we don’t play nice with the bully then the bully won’t play with us.  And, the general public will side with the bully because the bully has the nice toys…

Good negotiations, though, take a willingness by both sides, so that conversation evolves,  resulting in positive, cooperative actions embraced by both parties. There are other amateur radio operators who have made attempts to open up talks with Joe and crew.  What are the results, so far?

We can hope that Joe Taylor and his group of developers and leadership take a proactive role and join a conversation that is with a wider group of amateurs than just the WSJT enthusiasts.  We hope that they will play fairly, and cooperatively, with the rest of the amateur radio community.

Tomas Hood, NW7US, is a regular contributor to AmateurRadio.com and writes from Nebraska, USA. Tomas is the Space Weather and Radio Propagation Contributing Editor to ‘CQ Amateur Radio Magazine’, and ‘The Spectrum Monitor’ magazine.

This is a welfare check on you. Please leave a comment on how you are faring, what is happening in your situation with the lock-down.

Are you quarantined? Working from home? Did you lose your job? How are you doing during this crazy time?

What is going on with you during this challenging situation?

I talk about what I’m doing, too.  I’m quarantined at home.  I can work from home, as I am a senior software engineer.  I can do my job by remote access to a virtual workstation, through a secure VPN connection.  I’m blessed that I still can work during this lock-down.

But, I have a medical emergency – a dental problem – and trying to be seen by a dentist is difficult, because all of the local dentists were told to shut down their daily business and quarantine.  Only emergency appointments are being made!  I was finally, after two days of phone calls, able to schedule an emergency visit to my dentist!

I want to know: How do you use amateur radio, now that we are all stuck at home?  Are you using ham radio more, now?  Less?

Please leave a comment to let me know how you are doing, and answer the other questions, too.  I hope to hear from you.

I hope to meet you on the shortwave amateur radio bands.  I am usually using Olivia, or Morse code CW.  More information about Olivia: http://OliviaDigitalMode.net.

Be healthy, be safe, stay sane!

This past weekend (third full weekend in February, February 15-16, 2020) is the ARRL International CW Contest (ARRL DX CW link: http://www.arrl.org/arrl-dx ). This is interesting to my study of radio signal propagation as a columnist and as an amateur radio operator​ because of the contest objective: “To encourage W/VE stations to expand knowledge of DX propagation on the HF and MF bands…” This contest is a good way to get a feel for current propagation–though there are caveats.

Speaking of Morse code and the CW mode on our amateur bands: those of you using CW during contests, do you send by hand or by computer?  Do you copy the code by head, or do you use a computer for decoding?

Just curious about those of you who use CW. Do you send by hand or computer? Receive by head or computer?

In most contests like the ARRL DX CW contest, I copy by ear, and send mostly by rig keyer. If needed, I use a single paddle key with the Icom rig’s internal keyer to answer unique questions and so on.

Below is a quick demo of using the internal Morse code keyer in my Icom IC-7610 transceiver.

V47T, in the Saint Kitts and Nevis Island in the Caribbean, is calling CQ TEST in the ARRL DX CW contest.

Using the programmable virtual buttons, in which I programmed my callsign, NW7US, and other info, I answer and make a complete contest QSO.

In activity like the Straight Key Century Club (SKCC – https://SKCCGroup.com) K3Y special event, it is all manual. I send my Morse code using a WWII Navy Flameproof Signal Key, and decode with my ears.  It is contextual for me.

How do you do contesting Morse code?  Bonus question: How do you do logging while doing contest operation?

73 es best dx = de NW7US dit dit

Man, lots and lots of Morse code on the ham bands, this weekend. The CQ Worldwide CW Contest weekend was hopping with signals!

How did you do this weekend? How were conditions on the various contest bands?

Comment here and your report may make it into the propagation column in an upcoming edition of the Radio Propagation column in CQ Amateur Radio Magazine.

Here are a few moments as heard at the station of the CQ Amateur Radio Magazine propagation columnist, in Lincoln, Nebraska (yeah, that’s me, NW7US).

Here are the results of my dabbling with the Icom rig and this contest:

 NW7US's Contest Summary Report for CQ-WW
 Created by N3FJP's CQ WW DX Contest Log
 Version 5.7  www.n3fjp.com

 Total Contacts = 55
 Total Points = 8,979

 Operating Period: 2019/11/24 10:23 - 2019/11/24 22:51

 Total op time (breaks > 30 min deducted): 3:58:46
 Total op time (breaks > 60 min deducted): 4:45:17

 Avg Qs/Hr (breaks > 30 min deducted): 13.8


 Total Contacts by Band and Mode:

 Band       CW   Phone     Dig   Total       %
 ----       --   -----     ---   -----     ---
   80        8       0       0       8      15
   40        7       0       0       7      13
   20       25       0       0      25      45
   15       15       0       0      15      27
            --   -----     ---   -----     ---
 Total      55       0       0      55     100

 Total Contacts by State \ Prov:

 State       Total     %
 -----       -----   ---
                52    95
 HI              3     5

 Total = 1


 Total Contacts by Country:

 Country                      Total     %
 -------                      -----   ---
 Canada                           6    11
 Brazil                           5     9
 USA                              5     9
 Argentina                        3     5
 Costa Rica                       3     5
 Hawaii                           3     5
 Bonaire                          2     4
 Cayman Is.                       2     4
 Chile                            2     4
 Cuba                             2     4
 Japan                            2     4
 Mexico                           2     4
 Aruba                            1     2
 Bahamas                          1     2
 Barbados                         1     2
 Belize                           1     2
 Curacao                          1     2
 Dominican Republic               1     2
 French Guiana                    1     2
 Haiti                            1     2
 Honduras                         1     2
 Martinique                       1     2
 Montserrat                       1     2
 Nicaragua                        1     2
 Senegal                          1     2
 St. Kitts & Nevis                1     2
 St. Lucia                        1     2
 Suriname                         1     2
 US Virgin Is.                    1     2
 Venezuela                        1     2

 Total = 30


 Total DX Miles (QSOs in USA not counted) = 151,407
 Average miles per DX QSO = 3,028


 Average bearing to the entities worked in each continent.
 QSOs in USA not counted.

 AF =  83
 AS = 318
 NA = 124
 OC = 268
 SA = 137


 Total Contacts by Continent:

 Continent   Total     %
 ---------   -----   ---
 NA             32    58
 SA             17    31
 OC              3     5
 AS              2     4
 AF              1     2

 Total = 5


 Total Contacts by CQ Zone:

 CQ Zone   Total     %
 -------   -----   ---
 08           13    24
 03            7    13
 09            7    13
 07            6    11
 11            5     9
 13            3     5
 31            3     5
 04            2     4
 05            2     4
 06            2     4
 12            2     4
 25            2     4
 35            1     2

 Total = 13

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!