The Elmer's Shack
Digital Modes
Oh To See More!
By Jim Wright, N2GXJ
At one time mysterious, and known to but a few ham radio operators, a waterfall display is now ubiquitous, to the point of comfortable familiarity with most modern hams. For some, it was the venerable FLDIGI that offered them their first foray into “seeing sound”. For those Club-nostalgic historians out there, you might enjoy a time warp flash-back to “seeing sound” from 10 years ago in the March 2012 CrossTalk (http://bit.ly/3TGaROt). For many today, it has been WSJT that has made the introduction, with its scrolling display of multiple FT8 signals all in the same audio passband.
Certainly being able to see the activity for narrow band signals in a 3 kHz audio passband for an FT8 watering hole, like 14.074 MHz, has been great. With such a display of the audio passband, you can tell at a glance where the strong signals are (useful for pouncing), or where the less busy spots on the waterfall might be (for calling CQ).
To get that 3 kHz digitized sample of audio, some radios have a digitization device built-in. For other radios you can use an external device, like a Tigertronics SignaLink USB, for an audio passband to get converted into digits that can then be processed to create a frequency domain waterfall display.
All good, right? Not quite. Turns out that if this is all that you are looking at, you’ll be missing quite a bit of the bigger picture. Like what? Well, for example, you might miss out on making that needed contact with a DXpedition that’s not using the standard FT8 frequency (yes, this is a real thing). You’d never see it on the waterfall if all you were doing is tuning to a standard FT8 frequency, like 14.074 MHz, and looking at the 3 kHz audio bandwidth there.
So, what’s the solution to this? A solution is to simply “see more”. Get a receiving device, or a two-way radio, that can let you see more than just 3 kHz of the HF spectrum at a time.
To illustrate what it means to be able to see more than just 3 kHz of HF spectrum at a time, take a look at the waterfall picture in Figure 1. It is showing 20 kHz of the spectrum, instead of just 3 kHz at a time. What do we see there? Well, let’s take a look.
By Jim Wright, N2GXJ
At one time mysterious, and known to but a few ham radio operators, a waterfall display is now ubiquitous, to the point of comfortable familiarity with most modern hams. For some, it was the venerable FLDIGI that offered them their first foray into “seeing sound”. For those Club-nostalgic historians out there, you might enjoy a time warp flash-back to “seeing sound” from 10 years ago in the March 2012 CrossTalk (http://bit.ly/3TGaROt). For many today, it has been WSJT that has made the introduction, with its scrolling display of multiple FT8 signals all in the same audio passband.
Certainly being able to see the activity for narrow band signals in a 3 kHz audio passband for an FT8 watering hole, like 14.074 MHz, has been great. With such a display of the audio passband, you can tell at a glance where the strong signals are (useful for pouncing), or where the less busy spots on the waterfall might be (for calling CQ).
To get that 3 kHz digitized sample of audio, some radios have a digitization device built-in. For other radios you can use an external device, like a Tigertronics SignaLink USB, for an audio passband to get converted into digits that can then be processed to create a frequency domain waterfall display.
All good, right? Not quite. Turns out that if this is all that you are looking at, you’ll be missing quite a bit of the bigger picture. Like what? Well, for example, you might miss out on making that needed contact with a DXpedition that’s not using the standard FT8 frequency (yes, this is a real thing). You’d never see it on the waterfall if all you were doing is tuning to a standard FT8 frequency, like 14.074 MHz, and looking at the 3 kHz audio bandwidth there.
So, what’s the solution to this? A solution is to simply “see more”. Get a receiving device, or a two-way radio, that can let you see more than just 3 kHz of the HF spectrum at a time.
To illustrate what it means to be able to see more than just 3 kHz of HF spectrum at a time, take a look at the waterfall picture in Figure 1. It is showing 20 kHz of the spectrum, instead of just 3 kHz at a time. What do we see there? Well, let’s take a look.
Figure 1 : Seeing more with a wider waterfall
In this example, we see the “normal” FT8 in the 3 kHz from 14.074 - 14.077 MHz. And because this waterfall is wider in frequency, we also get to see the FT4 activity at the same time happening in the 3 kHz from 14.080 - 14.083 MHz. Nice! But there seems to be even more activity higher in frequency too. And that’s the bonus. Surprise! Turns out, in this example, there’s all kinds of FT8 activity happening up at 14.090 MHz. Without seeing there was activity there, you might never have thought to look there, to get a chance at P29RO (PAPUA NEW GUINEA).
The same trick works when chasing SSB (voice) and other signals too. Turning a tuning dial to try and catch a station calling CQ on USB is luck at best, unless you tune real slow. With a wider bandwidth view, you can see where they are, even if you are not listening where they are transmitting at this moment in time. The wider the bandwidth you can display, the quicker it is to assess where the activity is. This works not just for VHF and UHF, where the bands are very wide, but for HF frequencies as well.
Ever wonder what 20 Meters looks like during a sideband contest? Wonder no longer. Figure 2 is a screen shot during the recent CQ WW SSB contest. This display comes from a wideband SDR capable of digitizing the entire width of the 20 Meter band at one time. Look at all those signals!
The same trick works when chasing SSB (voice) and other signals too. Turning a tuning dial to try and catch a station calling CQ on USB is luck at best, unless you tune real slow. With a wider bandwidth view, you can see where they are, even if you are not listening where they are transmitting at this moment in time. The wider the bandwidth you can display, the quicker it is to assess where the activity is. This works not just for VHF and UHF, where the bands are very wide, but for HF frequencies as well.
Ever wonder what 20 Meters looks like during a sideband contest? Wonder no longer. Figure 2 is a screen shot during the recent CQ WW SSB contest. This display comes from a wideband SDR capable of digitizing the entire width of the 20 Meter band at one time. Look at all those signals!
Figure 2 : Wideband view of entire 20M band during CQ WW SSB contest
So let me ask you this. If you were operating remotely, what waterfall bandwidth would you prefer to be able to see? For me, it’s really not a choice at all.
Oh, how great it is to see more! Wouldn’t you agree?
First Ever ARRL International Digital – Add To Your Club’s Score
By Jim Wright, N2GXJ
The first ever. It is the weekend of June 4-5, 2022. Got a few minutes to make FT8 contacts? Want to help see your club, the Gloucester Co ARC, honored in QST magazine? It’s easy! Just make some contacts, and then submit an entry with ‘Gloucester Co ARC’ listed as your club to add your points to a combined club score!
As one of the premiere clubs in the USA, and possibly the world, participating can be fun, and adding your score to the group score is easy. As a group effort, every point helps. Maybe you’ll consider tossing a few points towards your club this way?
Contest begins 1800 UTC Saturday June 4 and runs through 2359 UTC Sunday June 5. You pick which hours you want to operate in that range. Submissions due within a week of contest end. If want help afterwards submitting, just email/call me (n2gxj, in club roster). All the gory details are here : https://contests.arrl.org/ContestRules/Digital-Rules.pdf.
This is a perfect contest tailored to hams like me. They even have a special scoring category overlay for All Enclosed Antennas and limited time (meaning all antennas enclosed within a building, like in my attic, and operated for 8 hours or less). You get one point for each unique callsign per band that you log during the contest. Extra points get added based on how far away the grid square of the station you contacted was from your grid square.
To set up WSJT for this, under settings, on the advanced tab, select special operating activity. Since the ARRL digital contest is new, I don’t see it as a selection option, but the NA VHF Contest can be selected, and gives the right exchange information. Can use that. The contacts will then automatically use your already configured callsign and grid square (“FM29” for those of us in Southern NJ) when making the contest contacts.
Wow. First ever for an annual ARRL contest? That doesn’t happen very often!
Let’s have some digital fun, and toss in some points for the club! Hope to “see” you on the waterfall!
By Jim Wright, N2GXJ
The first ever. It is the weekend of June 4-5, 2022. Got a few minutes to make FT8 contacts? Want to help see your club, the Gloucester Co ARC, honored in QST magazine? It’s easy! Just make some contacts, and then submit an entry with ‘Gloucester Co ARC’ listed as your club to add your points to a combined club score!
As one of the premiere clubs in the USA, and possibly the world, participating can be fun, and adding your score to the group score is easy. As a group effort, every point helps. Maybe you’ll consider tossing a few points towards your club this way?
Contest begins 1800 UTC Saturday June 4 and runs through 2359 UTC Sunday June 5. You pick which hours you want to operate in that range. Submissions due within a week of contest end. If want help afterwards submitting, just email/call me (n2gxj, in club roster). All the gory details are here : https://contests.arrl.org/ContestRules/Digital-Rules.pdf.
This is a perfect contest tailored to hams like me. They even have a special scoring category overlay for All Enclosed Antennas and limited time (meaning all antennas enclosed within a building, like in my attic, and operated for 8 hours or less). You get one point for each unique callsign per band that you log during the contest. Extra points get added based on how far away the grid square of the station you contacted was from your grid square.
To set up WSJT for this, under settings, on the advanced tab, select special operating activity. Since the ARRL digital contest is new, I don’t see it as a selection option, but the NA VHF Contest can be selected, and gives the right exchange information. Can use that. The contacts will then automatically use your already configured callsign and grid square (“FM29” for those of us in Southern NJ) when making the contest contacts.
Wow. First ever for an annual ARRL contest? That doesn’t happen very often!
Let’s have some digital fun, and toss in some points for the club! Hope to “see” you on the waterfall!
Figure : Credit your club with your score in first ever ARRL Digi contest this weekend
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Here comes FT-4!
By Jim Wright, N2GXJ Hold onto your hats again! The new high octane FT-4 digital mode is scheduled to be unleashed for general availability into the wilds of the amateur radio airwaves all over the world on July 15! This is the latest incarnation in the evolution of digital amateur radio modes from Dr. Joe Taylor’s venerable WSJT-X team. First publically announced in April, FT4 combines RTTY-fast contest contact speeds with an FT-8 like weak signals mode. How fast is it? In its initial incarnation, each transmissions last less than 4.5 seconds! In a QSO, stations alternate |
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between sending and receiving every 6 seconds. That’s 2.5 X faster than the 15 seconds between alternate TX and RX with FT-8. In early June, after more feedback from field trials, they’ve extended the time to sending and receiving every 7.5 seconds. Still “dang fast” if you ask me!
How much low signal ability is lost at these speeds? It’s relative. In its initial version, FT4 was claimed to be able to decode successfully down to under -16 dB, which is faintly audible. For those used to using RTTY, that’s far superior (by about 10 dB), and with the added benefit of not taking up as much bandwidth. After more feedback from field trials, they’ve narrowed the bandwidth from 90 Hz to 80 Hz, and added a third decoding pass ability, along with some other improvements, to result an improvement in S/N threshold down to -17.5 dB. For those used to using FT8, where decodes below -20 dB are often possible, it is not as good. But that’s still “dang good” if you ask me!
Deemed “too new” to be allowed to be used for field day this year, the RC version purposefully disabled itself so that it could not be used during this event. But it’s ready now. And so are your favorite tools, like N1MM+, Logbook of the World, and eQSL.cc to receive your logged contacts. The question is, are you ready? We’ll know soon! Starting Monday July 15, check for download availability at : www.physics.princeton.edu/pulsar/k1jt/wsjtx.html.
And stay tuned for other new news from the WSJT team. For the “low banders” out there, there are rumors stemming from an offhanded comment Dr. Joe Taylor, K1JT, made of a new mode in development targeting the new 630/2200 Meter low bands with an S/N limit near -35 dB!
Good DX, and have fun everyone!
How much low signal ability is lost at these speeds? It’s relative. In its initial version, FT4 was claimed to be able to decode successfully down to under -16 dB, which is faintly audible. For those used to using RTTY, that’s far superior (by about 10 dB), and with the added benefit of not taking up as much bandwidth. After more feedback from field trials, they’ve narrowed the bandwidth from 90 Hz to 80 Hz, and added a third decoding pass ability, along with some other improvements, to result an improvement in S/N threshold down to -17.5 dB. For those used to using FT8, where decodes below -20 dB are often possible, it is not as good. But that’s still “dang good” if you ask me!
Deemed “too new” to be allowed to be used for field day this year, the RC version purposefully disabled itself so that it could not be used during this event. But it’s ready now. And so are your favorite tools, like N1MM+, Logbook of the World, and eQSL.cc to receive your logged contacts. The question is, are you ready? We’ll know soon! Starting Monday July 15, check for download availability at : www.physics.princeton.edu/pulsar/k1jt/wsjtx.html.
And stay tuned for other new news from the WSJT team. For the “low banders” out there, there are rumors stemming from an offhanded comment Dr. Joe Taylor, K1JT, made of a new mode in development targeting the new 630/2200 Meter low bands with an S/N limit near -35 dB!
Good DX, and have fun everyone!