Archive for the ‘dx’ Category
The Olivia digital mode on HF radio is a mode capable of two-way chat (QSO) communication (keyboard to keyboard, like RTTY) over long-distance shortwave (HF) ionospheric propagation paths, especially over polar regions.
If you are interested in more than a logbook QSO (such as is typical with FT8 and other propagation-checking modes) but want to chat with other hams around the world using digital modes, consider Olivia as one option.
This video captures a few moments of two-way conversation on the Twenty-Meter band, up in the sub-band where 1000-Hz digital modes are commonplace. More narrow-bandwidth settings are used in a lower subband in the digital slice of Twenty Meters. More details about the mode are in the files section of this website: http://OliviaDigitalMode.org.
In 2005, SP9VRC, Pawel Jalocha, released to the world a mode that he developed starting in 2003 to overcome difficult radio signal propagation conditions on the shortwave (high-frequency, or HF) bands. By difficult, we are talking significant phase distortions and low signal-to-noise ratios (SNR) plus multipath propagation effects. The Olivia-modulated radio signals are decoded even when it is ten to fourteen dB below the noise floor. That means that Olivia is decoded when the amplitude of the noise is slightly over three times that of the digital signal!
Olivia decodes well under other conditions that are a complex mix of atmospheric noise, signal fading (QSB), interference (QRM), polar flutter caused by a radio signal traversing a polar path. Olivia is even capable when the signal is affected by auroral conditions (including the Sporadic-E Auroral Mode, where signals are refracted off of the highly-energized E-region in which the Aurora is active).
Currently, the only other digital modes that match or exceed Olivia in their sensitivity are some of the modes designed by Joe Taylor as implemented in the WSJT programs, including FT8, JT65A, and JT65-HF–each of which are certainly limited in usage and definitely not able to provide true conversation capabilities. Olivia is useful for emergency communications, unlike JT65A or the popular FT8. One other mode is better than Olivia for keyboard-to-keyboard comms under difficult conditions: MT63. Yet, Olivia is a good compromise that delivers a lot. One reason for this is that there are configurations that use much less bandwidth than 1000 Hz. 16 tones in 250 Hz is our common calling-frequency configuration, which we use lower down in the Twenty-Meter band, with a center frequency of 14.0729 MHz.
Q: What’s a ‘CENTER’ Frequency? Is That Where I Set My Radio’s Dial?
For those new to waterfalls: the CENTER frequency is the CENTER of the cursor shown by common software. The cursor is what you use to set the transceiver’s frequency on the waterfall. If your software’s waterfall shows the frequency, then you simply place the cursor so that its center is right on the center frequency listed, above. If your software is set to show OFFSET, then you might, for example, set your radio’s dial frequency to 14.0714, and place the center of your waterfall cursor to 1500 (1500 Hz). That would translate to the 14.0729 CENTER frequency.
The standard Olivia formats (shown as the number of tones/bandwidth in Hz) are 8/250, 8/500, 16/500, 8/1000, 16/1000, and 32/1000. Some even use 16/2000 for series emergency communication. The most commonly-used formats are 16/500, 8/500, and 8/250. However, the 32/1000 and 16/1000 configurations are popular in some areas of the world (Europe) and on certain bands.
These different choices in bandwidth and tone settings can cause some confusion and problems–so many formats and so many other digital modes can make it difficult to figure out which mode you are seeing and hearing. After getting used to the sound and look of Olivia in the waterfall, though, it becomes easier to identify the format when you encounter it. To aid in your detection of what mode is being used, there is a feature of many digital-mode software implementation suites: the RSID. The next video, below, is a demonstration on how to set the Reed-Solomon Identification (RSID) feature in Ham Radio Deluxe’s Digital Master 780 module (HRD DM780).
I encourage ALL operators, using any digital mode such as Olivia, to TURN ON the RSID feature as shown in this example. In Fldigi, the RSID is the TXID and RXID; make sure to check (turn on) each, the TXID and RXID.
Please, make sure you are using the RSID (Reed Solomon Identification – RSID or TXID, RXID) option in your software. RSID transmits a short burst at the start of your transmission which identifies the mode you are using. When it does that, those amateur radio operators also using RSID while listening will be alerted by their software that you are transmitting in the specific mode (Olivia, hopefully), the settings (like 8/250), and where on the waterfall your transmission is located. This might be a popup window and/or text on the receive text panel. When the operator clicks on that, the software moves the waterfall cursor right on top of the signal and changes the mode in the software. This will help you make more contacts!
+ NOTE: The MixW software doesn’t have RSID features. Request it!
Voluntary Olivia Channelization
Since Olivia signals can be decoded even when received signals are extremely weak, (signal to noise ratio of -14db), signals strong enough to be decoded are sometimes below the noise floor and therefore impossible to search for manually. As a result, amateur radio operators have voluntarily decided upon channelization for this mode. This channelization allows even imperceptibly weak signals to be properly tuned for reception and decoding. By common convention amateur stations initiate contacts utilizing 8/250, 16/500, or 32/1000 configuration of the Olivia mode. After negotiating the initial exchange, sometimes one of the operators will suggest switching to other configurations to continue the conversation at more reliable settings, or faster when conditions allow. The following table lists the common center frequencies used in the amateur radio bands.
Olivia (CENTER) Frequencies (kHz) for Calling, Initiating QSOs
It is often best to get on standard calling frequencies with this mode because you can miss a lot of weak signals if you don’t. However, with Olivia activity on the rise AND all the other modes vying for space, a good deal of the time you can operate wherever you can find a clear spot–as close as you can to a standard calling frequency.
Note: some websites publish frequencies in this band, that are right on top of weak-signal JT65, JT9, and FT8 segments. DO NOT QRM weak-signal QSOs!
We (active Olivia community members) suggest 8/250 as the starting settings when calling CQ on the USB frequencies designated as ‘Calling Frequencies.’ A Calling Frequency is a center frequency on which you initially call, ‘CQ CQ CQ. . .’ and then, with the agreement of the answering operator, move to a new nearby frequency, changing the number of tones and bandwidth at your discretion. Even though 8/250 is slow, the CQ call is short. But, it is narrow, to allow room for other QSOs nearby. It is also one of the best possible Olivia configurations for weak-signal decoding.
One person that always inspires me with his enthusiasm for Real HF Mobile radio, is Dave G4AKC.
Dave often takes off to the front of Blackpool promenade, on either his bike, or his recent electric trike towing a trailer load of equipment behind him, that puts most shack's to shame. His late night shift on the cold sea front, or early mornings well wrapped up, quite often produces some long path and rare DX surprises that you wouldn't get from the home QTH, due to a good signal bounce off the sea water and lower noise being out in the open making reception far easier.
The G4AKC website https://www.g4akc.co.uk/ where you can learn more about his exploits has now been added to my Blog right hand panel "Sites that do it for me links".
Another good Blog link EI7GL for Ireland has also been updated in "My Blog List" link again on the right hand panel.
|courtesy: KC8RP FT8 Info|
We are now half-way through this summer’s Sporadic-E season, normally the magic band’s best time of the year. The only exception to this being the winter months of those solar cycles that are robust enough to raise the F2 MUF up as far as 50MHz ... something that occurred for only two or three days during the peak of Solar Cycle 24.
Unfortunately, it really looks as if the old reliable bread and butter modes on 6m, CW and SSB, are fast going the way of the dodo bird, as very few signals on either of these modes have been heard here this summer. As speculated last year at this time, it seems as though the weak signal (WSJT) FT8 mode now reigns supreme on the band, which has come as a great disappointment to myself and many other diehard CW ops.
At the start of this year’s season I reluctantly decided to pay more attention to this mode and see if it could put any new DXCC entities into my 6m log ... if so, it would be time well-spent.
For the past several years, my main 6m interest has focused on European or South / Central American openings, which are usually unpredictable and short-lived. As usual, most of the season’s openings have been domestic, with signals from the central and south-eastern states being the ones most often heard. Usually, signals during these openings are strong and fairly reliable and lend themselves to easy two-way work on either CW or SSB. For the vast majority of summer time openings, FT8 is not needed, as signals are not weak.
For some reason, the popularity of this weak-signal mode on 6m continues to grow in popularity even though signals are so strong! Where this mode really shines is on the short-lived long haul openings to EU or on similar long paths from the PNW, of which there have been very few this season.
With everyone crowded into a narrow passband of ~ 2kHz, it doesn’t take much to mess things up for your neighbours if you don’t think carefully about how your operating can affect other users of that small sliver of space.
One of the most common examples of poor operating skills that I see is the seemingly endless CQ. This is much easier to do on FT8 than with conventional modes, as the software used can do this automatically for you, every 15 seconds ... while you fiddle with something else in the shack. I’ve seen some nearby stations call CQ continuously for over 60 minutes at a time, with no replies. What this does is make it difficult for other nearby users to actually hear / decode any weak signals on the band that are being covered by the loud CQing station(s) during this entire span of time. Strong local signals can wreak considerable havoc with weak-signal mode software as it's just not designed to happily handle strong signals and do a good job of decoding weak ones at the same time! Please think about this if you are one of those long CQers ... you are not the only one trying to use the band.
Another observation has to do with 'sequencing'. FT8 users must decide if they will transmit on the ‘even’ or on the ‘odd’ 15-second sequence. If you, and all of your neighbours are loud with each other, then it makes sense that everyone is better off operating on the same sequence. This way, all locals are transmitting at the same time which means they are all listening at the same time as well ... nobody causes QRM for one another if everyone uses the same sequence.
This comes off the rails very easily when just one or two strong neighbours choose to transmit during the receive sequence being used by everyone else.
There has been a long-standing precedent for sequencing, established and utilized by meteor-scatter operators for several decades. It calls for stations on the eastern-most end of a path (Europeans for example) to transmit on ‘evens’ ... the ‘0-15’ and ‘30-45’ second segment of each minute. Stations on the western-end of the path (NA) transmit on the ‘odds’ ... ‘15-30’ and ‘45-60’ second portion of each minute. When looking towards JA later in the day, everything reverses for NA stations, as they now become the eastern-end of the path.
Some operators seem to get totally confused by this or don’t check to see what sequence is being used locally before starting to operate ... while some don’t really seem to care.
I’m not complaining about what a given amateur chooses to do but simply describing some of the roadblocks to better use of FT8 and why it is not necessarily very well-suited for 90% of the typical propagation seen on 6m Es.
Many of the newer stations often seem to be using poor or makeshift antenna systems on 6m and are often not able to hear stations responding to their CQs, which may be strong enough locally to disrupt reception for those that are able to hear weaker signals.
I have deliberately made a point of never calling CQ on FT8. From decades of CW DXing I have come to understand that it’s much easier to work DX, on any band, by spending your time listening ... and then calling when the time is right. It’s no different with FT8, yet I see CQs that go on forever. Some will argue that if nobody called CQ, then there would be nobody to hear, which is of course valid ... the reality is, most amateurs cannot resist calling CQ, especially DX stations who enjoy working a pileup. There seems to be no shortage of CQers and those seeking DX should take advantage of that fact.
One loud station was seen yesterday calling another for over 90 minutes-straight. Perhaps he had wandered away from his shack and had forgotten to ‘Halt Tx’ before leaving! FT8 users need to understand how to use their software efficiently.
As for PNW to EU propagation this summer, it has been almost non-existent although I have worked CT1HZE in Portugal and JW7QIA in Svalbard ... by listening ... listening ... and calling briefly, both on FT8. In both cases, signals were brief but strong enough for CW! During the short-lived appearance of the JW7, two NA stations were noted calling ‘CQ JW’ the entire time. Perhaps if they had spent this wasted time more wisely by listening, they would have worked JW.
I’m happy to report that Svalbard was a new DXCC entity for me on 6m, #88, and the first 'new one' in a few years.
It seems that when used sensibly, FT8 is a useful application to have in your DX toolbox ... but for most daily summer Es operation, it’s just not needed. CW or SSB is well up to the task most of the time, even for small stations. Where FT8 shines is on the very brief, often unstable, long haul (EU-NA or JA-NA) paths and then, only if your neighbours don’t do things that will get them into the naughty-corner!
Now, let’s see what the second half of the season has in store for the magic band .... maybe the best is yet to come.
When it comes to crystal radios, there is nothing revolutionary regarding the CR-1’s basic circuitry but for some odd reason, it has achieved cult-like status as well as high dollar value.
|courtesy: Scotts Crystal Radios|
The article that piqued my interest appears on 'Scott's Crystal Radios' website and makes for an inspirational read, eventually revealing the inside core arrangement of the ferrite-loaded tuned circuits via an actual X-ray of the device! By the way, if you are looking for a nice set of older headphones, Scott's website is the place to visit!
|courtesy: Scott's Crystal Radios|
Scott was eventually able to achieve performance equal to that of his borrowed CR-1, with his own slightly modified versions, all in a similar-sized footprint. Perhaps this is one reason why the CR-1 is so much sought-after, as good performance in a very small package is not the norm when it comes to crystal radios. It's usually a case of ‘the bigger, the better’ when it comes to performance.
A recent search of my junque box revealed several NIB ferrite loopsticks that would allow a potntial reproduction of this interesting circuit.
Several years ago I spent an eye-opening winter learning about DX crystal radios as up to that time I had always believed it would be impossible to hear anything other than strong local signals on a crystal radio. I quickly discovered that there was a very large Crystal Radio Yahoo Group where menbers were working at the leading edge of crystal radio design. I also found that the group sponsored an annual Crystal Radio DX Contest which inspired me to dig deeper.
It wasn’t too long before I decided to join the fun and attempt to build a crystal radio DX-machine but I was in for a few surprises and a long learning curve ... it seemed that hearing broadcast band ‘DX’ on a crystal radio (anything other than loud locals) was not going to be an easy task!
Over the course of several months I tried many types of variable capacitors, tank coil configurations and antenna tuning circuits. I even erected a dedicated antenna system for the various experimental circuits I was putting together ... an 'Inverted-L', 50’ straight up and 70’ horizontal, along with a ground rod connected to several buried radials.
I quickly learned about something I normally didn’t have to worry about when working with ‘active’ devices and that was overcoming system and component losses. In critical crystal radio design, it’s all about minimizing the losses in every stage and every component in the system since there are no amplifiers to help overcome these losses. Your system is only as good as the weakest link. In true crystal radio DXing, no active devices are permitted ... it’s just your crystal radio and the energy generated at some, hopefully far away, transmitter site!
After several months, I eventually ended up with a well-performing triple-tuned set that used lots of 'trapping' because of all of the very strong nearby signals here ... eight 50kW locals!
A description of the learning curve, with several do's and dont's to help new builders, can be found on my website here.
Back then, 80 stations were logged (from my location on Mayne Island in SW British Columbia) over the one-week Crystal Radio DX Contest.
SAN FRANCISCO, CA
100 MILE HOUSE, BC
MERCER ISLAND, WA
DAWSON CREEK, BC
NEW WESTMINSTER, BC
SALT LAKE CITY, UT
SAN ANTONIO, TX
ST. MARIES, ID
MEDICINE HAT, AB
TWIN FALLS, ID
LAKE OSWEGO, OR
ST. PAUL, AB
OREGON CITY, OR
SAN JOSE, CA
LAKE OSWEGO, OR
BRIGHAM CITY, UT
Old notes indicate that there were 14 stations at S9 or higher, requiring heavy trapping to hear anything close to their frequencies.
|My recent interest made me wonder what the situation is today when it comes to the number of strong local ‘blowtorch’ signals, surely the bane of all crystal radio DXers? Although there have been a few changes over the years, a quick scan of the band during the prime DX evening hours found that although one of the blowtorch signals (at 600kHz) was now gone, another had appeared at 1200kHz ... sadly no net difference.|
The top end of the band, always a prime area for good skywave DX, is unfortunately still dominated by a huge signal from KVRI just across the water near the Canadian / U.S. border. If KVRI were silent, the top end would be a wonderfully quiet hunting-ground for new catches. The new local blowtorch (CJRJ) on 1200 kHz will now cause problems for the middle of the band, which was always a good region for DX.
So it seems overall, there hasn’t been a huge change here other than in the middle of the band. It looks as though there are still some good watering-holes to be had but several traps will still be needed in any new system.
Once my present radio-bench project is finished (a '36 RK-39 crystal power oscillator) I’m looking forward to more research and design of a couple of new systems, starting with something similar to the CR-1 as well as some experimentation with toroidal coils. I always find the research and planning phase of any new project more interesting and fulfilling than the actual construction and implementation! Hopefully I’ll have something ready for the fall DX season!
Thanks to VA7MM, I will also have the loan of an original CR-1 next winter to make comparisons to any clone that I might build!
If building a DX-crystal radio is something that might interest you, there are several great websites offering inspiration and helpful info. The links for these may be found at the bottom of my own crystal radio page. As well, there are two active crystal radio groups on Facebook, where daily two-way discussion can be had.
Perhaps, with enough new interest, we can even revive the annual Crystal Radio DX Contest!
We just got back from a very enjoyable trip to Roatan Island that included 8 friends vacationing together. The snorkeling and beach time were lots of fun. We stayed at the Seaside Inn, highly recommended.
Of course, I took along some ham radio gear and made radio contacts from the island using the Slacker DXpedition method. The station was a Yaesu FT-991 driving an end-fed half wave wire antenna, cut for either 20m or 40m. I operating as K0NR/HR9 and my co-slacker Denny was on the air as KB9DPF/HR9. (Reciprocal licensing info is available from the Radio Club De Honduras.) We started out on SSB but that was tough going with poor propagation, so we soon found that FT8 was more effective.
We were pleasantly surprised with how well FT8 worked out for us as it was very compatible with the Slacker DXpedition philosophy. Here are the Top Ten Reasons to Use FT8 for Island Time DX:
- You can listen to your “island time” playlist while working DX.
- You don’t annoy your fellow vacationers by screaming into the microphone.
- You don’t have to worry about remembering proper phonetics.
- You can read the other station’s QRZ page while the computer completes the contact.
- You have time to visit the restroom without missing any contacts.
- You can upload your log to LoTW while operating.
- You have time to mix up a rum punch while making QSOs.
- It doesn’t matter if you slur your speech a bit due to that extra rum punch.
- If the run rate is really slow, the pc screensaver will kick in to entertain you.
- You can actually make contacts when propagation sucks.
Over the past few months I’ve spent some time tuning around the international shortwave bands.
I vividly recall how jam-packed these bands were when I first discovered the magic of radio, back in the peak years of Solar Cycle 19. Much has changed in this part of the radio spectrum since then, but after having read so many dire comments describing the demise of international SW broadcasting, I was pleasantly surprised at what I discovered.
Although there are certainly not the large numbers of stations there once were, there is still a large amount of activity to be found throughout the various bands allocated to international SW broadcasting.
Trying to keep track of station schedules and frequencies is a hobby unto itself but now made easier with the availability of so many online information sources. As when younger, I found the best way to stay organized was to keep a SW logbook, eventually settling on a simple ‘diary’ format which is still evolving.
Its next refinement will be an additional notebook having separate pages devoted to each individual frequency within a given SW band. This will allow for updating frequency information from various postings of the daily online ‘heard’ reports.
I’ve always had a great interest in QSLs and collecting cards was one of the things that initially attracted me to SW radio back as a pre-teenaged DXer. For me, not much has changed in the last several decades and I still enjoy QSLs ... the real, traditional cards, as opposed to the now popular e-card. For me, an e-card just doesn’t have much appeal for some reason but for many others, they work just fine.
As I slowly re-learn much of what I had forgotten about SWL’ing, I discovered that there are still many SW broadcasters that will acknowledge a reception report with a real paper card ... just like the good old days!
If you are keen on doing some serious listening, I cannot recommend the WRTH highly enough.
Studying the latest WRTH revealed the QSL policies of most international as well as domestic SW broadcasters as well as contact information. It is a superb annual reference and well worth the investment! With this information in hand, my listening has become more focused on recording and submitting reception reports to those stations still practicing the courtesy of acknowledging reports with a traditional QSL. Many stations also issue an e-card, but these are of little interest to me at present.
With a small amount of spring-summer time devoted to SW listening, I generated and submitted a few reception reports along with linked audio files on my website ... so far, the following QSLs have arrived:
|Radio Exterior de Espana|
|15520 kHz - Noblejas, Spain|
|Radio Free Asia|
|9950 kHz - via IBB on Tinian Island, S. Pacific|
|All India Radio (AIR)|
|9865 kHz - Bengaluru, India|
|DX Clube Sem Fronteiras Broadcast via WRMI 7730 kHz, Miami|
|T8WH - 9965 kHz Palau, South Pacific|
|HSK9 - 5875 kHz Udon Thani, Thailand|
|Radio Liangyou - Hong Kong|
|9275 kHz via Bocaue, Philippines site|
|Radio Romania - 9730 kHz - Bucharest, Romania|
|Radio Nikkei 2|
|3935 kHz - Chiba, Japan|
I’ll do an upcoming blog on some of the great information and online sites to support international SW listening activities.
This summer's 6m sporadic-E (Es) DX season is now well past the half-way mark and things have been different ... a lot different. For me, the past 40 plus summers of activity on the magic band have always been interesting, if not down right exciting ... particularly when the band opens to Europe from the west coast.
These usually very short-lived paths have been my main interest for the past several years and the bread and butter mode is normally a fast CW exchange, usually taking less than 20 seconds before signals would vanish, as the always quirky west coast path to Europe would jump to another region. But this has all changed dramatically.
I have seen many strong openings involving loud FT8 signals from various parts of North America but when tuning down to the CW/SSB section of the band, found nothing but ghostly silence! Gone are the familiar voices of friends met every summer for decades or the recognition of an old friend's fist on CW ... for me personally, most of the magic was missing this summer. I wonder if this is all part of the natural evolution of amateur radio or does the FT8 revolution signal the long term fate for many of the older conventional modes?
|Track the pole's movement here.|
|July 18th courtesy: http://www.on4kst.org/chat/index.php|
|July 20th courtesy: http://www.on4kst.org/chat/index.php|
|Overnight decodes July 8-9|
Thanks to Paul, K7CW, for doggedly sorting through my all-night decode file which may be viewed in full here.
With just a couple of weeks left in the normal Es season, it will be interesting to see if FT8's extra few db will extend it longer than usual!