The Murchison Wide-field Array (MWA) is a radio telescope located in a remote part of western Australia and it's made up of 4,096 antennas designed to detect radio waves between 70 and 300 MHz. One of its primary goals is to detect very weak radio signals coming from the reionization when the first stars and galaxies were forming.
The MWA radio telescope is located inside a 300-kilometre-wide radio quiet zone which is supposed to eliminate all signals from terrestrial sources. This is very important because any signals from a source on Earth would likely be much stronger than any signals from the cosmos.
It turns out that the 300km wide quiet zone may not be wide enough as the array was still picking up some interference as shown below. The image shows a signal between the frequencies of 181.5–187.5 MHz, and with times between 35 and 50 s.
By analysing the signals, they were able to determine that the interference was from Australian digital TV channel 7 and the signals was being reflected off an airplane traveling at 38,400 feet (11.7 kilometres) in altitude and at a velocity of 792 kilometres per hour.
A recent study has found that aircraft are present above the horizon line at the site at least 13% of the time, establishing a lower limit on the data potentially lost to reflected interference from aircraft.
It is now hoped that this type of new interference can now be modelled and be subtracted from the final data from the observations.
A highly detailed account of how they found the interference can be found HERE
Comment... I found the above news item of interest for a number of reasons. There are similar but smaller VHF radio astronomy telescopes scattered across Europe as part of the LOFAR network and these must surely suffer from similar interference considering the higher density of aircraft over Europe and the extensive DAB radio network.
It's also a reminder that the VHF bands are certainly not 'line of sight'. There are multiple propagation modes that allow signals to be heard even briefly over many hundreds of kms.
For the last few years, the EI1KNH, EI0SIX and EI4RF beacons have been operating from a site to the south of Dublin with an excellent take off to the east towards the UK. Now due to a change of ownership of the site, the radio beacons will be turned off on Saturday 15th February 2025.
The EI4RF beacon on the 70 MHz band (4m) will be the first to re-locate and it is hoped that a site will be available in the same general area. All going well, it will be operational for the start of the Sporadic-E season in May. It is hoped that EI0SIX operating on 50 MHz (6m) will be added soon after.
Getting the EI1KNH40 MHz and 60 MHz beacon back on air will take longer. The change of location will likely require a change of callsign and this must be applied for. Hardware considerations at the new site should mean that the 60 MHz (5m) beacon will appear first but the 40 MHz (8m) beacon may be more problematic.
As soon as there are any more developments, I'll post them on the blog.
In a recent video on his popular Oxford Shortwave Log YouTube channel, Clint, M0OXF lamented on how few stations are now listed in the 2025 edition of the World Radio TV Handbook.
I have embedded the video at the bottom of this post.
Just by chance, I came across the 1991 edition of the same publication today and I had a look at the Long Wave section.
As might be expected, there were no shortage of stations back then in Europe and in Asia.
The list for Europe, Africa, the Near & Middle East is shown above and below..
As was common with long wave stations of the day, power levels up in the hundreds of kilowatts were pretty common.
The other region of the world where Long Wave was used was the eastern part of the then USSR and Mongolia. The first section is shown above with the second part below...
This was of course a time when broadcasting on the Long Wave, Medium Wave and Short Wave bands was a source of information and entertainment in a pre-Internet World.
The video below from Clint shows the current state of the Long Wave band in 2025...
While the WSPR beacon mode is very common on the HF bands, it seems to have been largely ignored worldwide by the VHF community.
The exception however is in Australia where there is a very active group of radio amateurs sending and receiving WSPR signals on the 50 MHz and 144 MHz bands.
The map above shows some of the typical paths recorded on WSPR on the 144 MHz band in Australia. The longest distances are usually the sea paths across the Great Australian Bight.
John, VK2IJM compiled a list of the longest paths on 144 MHz during the months of December 2024 and January 2025.
As you can see, some paths were close to 2800 to 2900 kms.
John, VK2IJM writes... "Many thanks to those that had their rigs turned on and uploaded spots during December and January.
I've collated the 2m results already (see above) and they show a quite amazing summer for troppo downunder. We didn't quite crack 3000km this summer, but the 2850km spot between VK7DC and VK6CPU must be close to a 2-way record.
The longest spot was from VK6ZE to Leigh VK2KRR. 2m ES were slow in December but picked up in January with several large E storms. The big troppo this summer was across the bight to VK6, where we had days on end with spots to VK3 and VK7 and almost nothing to ZL, which is typical of La Nina years."
It would be nice to see more 144 MHz WSPR activity in places like Europe, USA and Japan.
FOSDEM is a free event for software developers from all over Europe to meet, share ideas and collaborate and it held this year in Brussels on the 1st & 2nd of February 2025.
Out of the 1000+ lectures, a few were radio related...
Saturday - 1st Feb 2025 Using AI hardware accelerators for real-time DSP on embedded devices - NPU, TPU etc, M17 and OpenRTX: one year later The AFF3CT framework for building numerical communication chains HAMNET - Status Update RF Swift: A Swifty Toolbox for All Wireless Assessments SDR++, a modular, cross-platform SDR utility Broadband data transfer over USB for GNU/Linux: 1-2 GHz (L-band) SDR receiver Meshtastic - off-grid communication for everyone Yet another new SDR runtime?
Some of these talks have slides available in PDF format and there are links if you want to explore the subject more.
HAMNET is a Highspeed Amateur Radio Multimedia NETwork developed from an experiment into a stable infrastructure, particularly in German-speaking countries. It generally connects unmanned amateur radio stations via microwave links using the IPv4 and BGP protocols and provides a platform for networking amateur radio applications.
M17 is an open source protocol for digital radio and its goal is to allow radio amateurs to communicate via digital voice and data. The M17 team are also developing open source hardware in conjunction with this. The net result is to have hardware and software that is designed for the amateur radio community and is not dependant on commercial companies or third parties. In other words, M17 is designed by radio amateurs for radio amateurs.
Meshtatsc is described as follows... "Meshtastic is an open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices. It uses Lora-P2P with dedicated radio chips and forms ad-hoc meshes. In HAM mode the encryption is switched off and the ISM airtime restrictions are lifted."
Meshtastic goes beyond the confines of the amateur radio bands and allows anyone with an interest in electronics to experiment on the UHF licence free ISM radio bands like 868 MHz in Europe and 915 MHz in North America. Radio amateurs have the ability to use higher power on bands like 433 MHz.
Thanks to Amateur Radio Weekly, I came across a recent contact on the 10 GHz band that took place between the states of Tennessee and Virginia in the United States.
The video shows a successful contact on FM between N4OFA in grid EM86RS and K4LY in grid EM85WB. The distance was about 190kms or 120-miles which on FM over an obstructed path is impressive.
I looked at the path profile and it seems that the most likely mode of propagation was knife edge diffraction over the mountains in between.
It was curious to note the QSB (fading) on the signal as well. Reason? Vegetation moving? Some aircraft scatter?
In the video description, Mike N4OFA writes... "This is a video that amazed both of us, signals were very strong, I found Doug's beacon where he was portable near his house. A quick touch up with my wonderful tripod and he was hitting S9 with quick QSB. What kind of propagation is this? Doug's FM signal sometimes hits S9 on my little FT817nd. Note: no elevation on the dish at all, no rain cells between us. We did not try CW as there was no need since we could carry on a conversation even on FM."
See video below...
Addendum: Jacob, KG4AUW on Twitter suggested that the path might have been possible by bouncing signals off fire watch towers on the skyline ridge of the mountains.
Over a path of 190kms, it's probably impossible to be sure but there seems to be plenty of reflective metal surfaces there.
I recently came across details of this remarkable contact on the 1296 MHz (23cms) band.
On the 22nd January 2025, the PI9RD station at the Dwingeloo radio telescope facility in the Netherlands managed to make a contact with HB9Q in Switzerland by bouncing signals off an INMARSAT satellite in geosynchronous orbit.
While it is reasonably common for stations on the 1296 MHz band to bounce signals off the moon and for geostationary satellites like QO-100 to relay microwave signals, the signals on this occasion were physically bouncing off the metalwork of a geosynchronous satellite.
When you consider that satellites in a circular geosynchronous orbit are at an altitude of 35,786 kms rather than a few hundred kms for satellites in low earth orbit then it's even more remarkable.
Jan, PA3FXB gave this account of the contact...
Today at PI9RD (25m Dwingeloo telescope) we succeeded in completing two QSO’s on 23 cm with HB9Q via reflection off geostationary satellites.
This journey started in May 2013 when Andreas DJ5AR and I (PA3FXB) had our first 23 cm ISS bounce QSO using our 3 m dishes. We started experimenting with the big dish using smaller satellites.
In 2016 we (DJ5AR and PI9CAM) had a QSO via reflection off an old orbiting weather satellite. Since then, we started thinking of a QSO via reflection off a geostationary satellite. Much much, farther away but virtually fixed so no tracking challenges.
With HB9Q we tested using a cluster of ASTRA satellites using the double tone of JT65. We did not hear or see anything, but computer analysis showed that the signal was there! We did it again and got the same result. People familiar with the satellite world suggested us to use INMARSAT as passive reflector.
120W into a 25m dish on the 23cm band
The first INMARSAT-test with HB9Q was at the end of 2023 and produced a nice stable -23 dB and decoding signal on our screen. We then used Q65-120A. Our output power is much less so Dan did not see our signal and a strange thing happened: After a few minutes the signal disappeared….
Thinking about this and talking to satellite operators brought us to the conclusion that the orientation of the solar panels of the sats is an important thing to get good reflections. Nobody could tell us how it works on the different sats but there appear to be two systems. Constant moving of the solar panels and moving them in big steps every now and then. This might have happened when the reflection disappeared….
With this uncertainty about the solar panel position we decided to simply try a few INMARSATs. Today was the day ??
We started with the same INMARSAT GX5 we used in 2023 and we immediately saw -21 dB signals from Dan. This time we used Q65-60A to save our SSPA’s. After calling several times we received R-32 from Dan! Thanks to averaging!
And some minutes later after sending our RR73’s several times we received 73 from Dan. So, we made it!!! Just barely but we made it ??
Then we decided to try another sat. We went for INMARSAT 4A F2 (Alpha) and we experienced much stronger reflections! -15 / -24 dB. Dan was speaker copy in Dwingeloo! We had an ‘easy’ QSO??
After that we tried two other INMARSATs but with no result at all. So, here we are, two QSO’s via passive reflection off two INMARSATs. We think this has never been done before by radio amateurs.
It made us very happy! Thanks to Dan and his patience and many tests!
***
Well done to all concerned. For some details of other interesting contacts on the 1296 MHz band, see my Microwave page.
High-frequency Active Auroral Research Program (HAARP) is based in Alaska and it's a high-power, high frequency (HF) transmitter for studying the ionosphere. The principal instrument is a phased array of 180 HF crossed-dipole antennas capable of radiating 3.6 megawatts into the upper atmosphere and ionosphere. Transmit frequencies are selectable in the range of 2.7 to 10 MHz.
Update: Note that due to hazardous winter road conditions along the highways leading to the HAARP facility, the January Research Campaign has been delayed by 1 day. Dates updated below.
The research team have announced that they will be carrying out tests from the 28th of January to the 2nd of February 2025.
The press release is shown below and I've added a map to show location and distance.
To: Amateur Radio & Radio Astronomy Communities
From: HAARP Program Office
Subject: Notice of Transmission
The High-frequency Active Auroral Research Program (HAARP) will be conducting a research
campaign with operating times specified in the table below. Operating
frequencies will vary, but all HAARP transmissions will be between 2.75 MHz and 10 MHz. Actual
transmit days and times are highly variable based on real-time ionospheric and/or geomagnetic
conditions. All information is subject to change.
This campaign is being conducted in support of research proposals from UAF, the University of
Florida, the Naval Research Laboratory, Los Alamos National Laboratory, Cornell University,
Dartmouth College, Embry-Riddle Aeronautical University, and the University of Houston.
Research topics for this campaign include VLF generation and ducting, studies on STEVE airglow,
and space debris detection.
This campaign will also support the GIRAFF rocket launch from Poker
Flat Research Range, which is investigating the mechanisms that cause flickering and pulsing
within the aurora. More information on GIRAFF is available here:
Note that a number of experiments will be conducted based on the critical frequency (f0F2)
determined by the Gakona ionosonde. The included transmission notice supplement contains
information on the frequencies HAARP is authorized to transmit. HAARP transmissions will only
occur on our authorized frequencies.
There are no specific data collection requests from funded investigators, but reception reports are appreciated and may be submitted online via our web form
The image above is an annotated ionogram from HAARP that describes features that may be of
interest. Note that f0F2 is calculated at the top left.
f0F2 is the critical frequency of the F2 layer of the Earth’s ionosphere. This is the frequency at which radio signals stop refracting off the ionosphere and begin passing through to outer space. For certain HAARP experiments that deal with interactions in the ionosphere, transmission frequencies below f0F2 are desirable, while for other experiments (such as those involving high altitude satellites), staying above f0F2 is required.
The 145 Alive Group are organising an activity period on the 2m amateur radio band in the UK & Ireland on Sunday the 26th of January 2025 from 12:00 to 15:00 UTC.
This is not a contest and the aim is to promote more activity on the 2m amateur radio band. The approximate location of the net controllers are shown in the map above and they will be operating on the FM channels from 145.250 to 145.575 MHz.
Don't worry about who is operating where, just tune around and see who you can hear. All you need to do is to call in and give a report. If you listen for a few minutes, you'll get the format of the exchanges.
The weather isn't looking great with a named storm crossing over the UK & Ireland on Sunday. This may result is fewer stations taking to high ground.
While the summer Sporadic-E season from late April to early August is well known, there is also a much smaller Sporadic-E season during the mid-winter.
On the 14th of January 2025, there was one such opening in North America. This one was a bit unusual in that it happened during the hours of darkness and the maximum usable frequency (MUF) went as high as 107.7 MHz.
Mike Schaffer, KA3JAW writes... "There was a good Sporadic-E opening on the 88-108 MHz FM broadcast band on the 14th of January 2025. There was USA Winter Season FM Es reported on three spotters, Wlogger, FMLIST, DXMAPS during the midnight hours up to the top of the band.
Two events - the first occurred from 0506 - 0655 UTC from the Northeast to the upper Midwest. The second shorter event from 2313 - 2323 UTC was from the Northeast to the lower Midwest."
Looking through the logs, the minimum skip distance was 952kms while the longest was 2289kms, close to the maximum for one hop Sporadic-E.
Every Tuesday evening, there is a local net here in Cork on the VHF bands where a few of us get on air for a chat for about an hour. Over the course of the month, we alternate between 2m FM, 70cms FM, 4m FM and 70cms DMR.
If there is a fifth Tuesday in a month, we sometimes use it for experiments. As Tuesday the 31st of December was the fifth Tuesday in the month, a few of us tried the Rattlegram app.
Rattlegram is an app for a smartphone and it allows users to send short text messages over the radio. The beauty of the app is its simplicity. There is no need for wires or interfaces, the user just needs to hold their smartphone next to the microphone and loudspeaker of their radio.
The burst of data from the Rattlegram app only lasts for about two seconds. It's really simple to use. You just compile a short message on the app, press PTT on the radio and tell the other person you're sending a message, hold the microphone of the radio next to the smartphone and press 'TRANSMIT' on the app. The person on the receiving end gets the error free message on their app a second or two later.
Test Results... There were four of us on air for the net... Denis EI4KH, Robbie EI3GGB, Don EI8DJ and myself EI7GL. Over the course of about two hours, we successfully exchanged short text messages with the app over the air.
The tests on FM on the 145 MHz and 50 MHz bands were nearly all 100% successful. The main thing here was to make sure that the volume on the radio was turned up to a reasonable level and the phone was held near the radio.
It was interesting to see that the tests on 50 MHz SSB were also successful. The digital burst of Rattlegram is made up certain audio frequencies and on FM, these frequencies are copied exactly.
On SSB, you will never tune exactly to the other persons frequency. You can tune your radio to make the other person sound ok but if you were to relay something like music then you'd know something wasn't quite right.
With Rattlegram over SSB, the tones must be off slightly but it didn't seem to matter.
We also tried using Rattlegram with DMR via a local repeater and simplex. Both tests were a failure and it looks as if the Rattlegram audio signal is distorted to such an extent that decoding wasn't possible.
As for why DMR failed? One theory put forward was the time division multiplex nature of DMR as the signal is chopped up.
(Addendum: Brian, EI8EJB reports using Rattlegram without any issues on FM simplex but there could be issues when trying to go through a FM repeater. See comments to blog post)
The image above shows what the Rattlegram app looked like on my phone for the tests. The oldest traffic is at the bottom and the newest messages appear at the top of the screen.
The three dots at the top right allow the user to access the menu items. From there, you can select CALL SIGN to put in your call as otherwise, you will appear to others as ANONYMOUS.
To clear the screen of all the text messages, select DANGER ZONE and then Delete Messages.
The longest message that you can send seems to be around 3-4 short lines of text.
Rattlegram - What's its purpose??? ... The question that obviously arises is why would you need to Rattlegram anyway? The example often offered is that in the case of a natural disaster like a flood, storm, hurricane, wildfire, etc, mobile phone cell towers can be destroyed.
In that scenario, your mobile phone without cell coverage reverts to being a fancy camera with a calculator. Rattlegram allows the user to send short text messages over the radio until full communication is restored.
I can also see Rattlegram being used a simple tool in an scenario where I just want to pass on some basic information like say a phone number to someone.
In conclusion... The purpose of our experiment was to introduce participants of the net to the Rattlegram app and to gain experience of seeing it in use. As with the conclusion of many experiments, it raised for me more questions.
1) How well will it perform under weak signal conditions on FM or SSB? How far down into the noise will the signal go and still work?
2) Will it work on the HF bands with multipath? Will it work on a circuit with multiple hops?
I get the feeling that Rattlegram is a bit like a solution looking for a problem. It's a tool that I'm sure some resourceful operators will find a use for.
Further information... There are plenty of videos on YouTube about Rattlegram or under its older name Ribbit.
Andreas HB9BLA has a nice video below which gives a good overview of the Rattlegram app.
Over the last few years, I've reported on many Trans-Equatorial Propagation (TEP) contacts from South America to the Caribbean on the 144 MHz band... links on my 144 MHz page.
For this mode of propagation at 144 MHz, signals must generally cross the Geomagnetic Equator at right angles. This usually means that stations in the south of Brazil work places like Guadeloupe, St Martin & Puerto Rico. Stations near Buenos Aires in Argentina work stations in Curacao & the Dominican Republic.
There has been a distinct lack of 144 MHz TEP openings further west in South America mainly due to a lack of stations at one or both ends of the paths.
So it was a really big surprise to hear that Carlos, LU7MC in the west of Argentina managed to complete a contact with Yuri, UT1FG/MM on a ship to the north of Cuba!
The contact was made using the Q65B mode on the 9th of December 2024 at 01:34 UTC. This is just after 20:00 local time for both stations which is about the peak time for evening type TEP.
The distance was in the region of 6474 kms which is exceptionally long for a 144 MHz TEP contact for South America.
The map above shows just how close UT1FG/MM was to the Florida. His ship was just 80kms south of the road going to Key West and about 170kms south of Miami.
It's hard to know for certain but I suspect that the TEP signal from LU7MC almost certainly reached Florida. It was most likely that there was nobody active there and looking.
Mode of Propagation... As indicated already, the mode of propagation was TEP - Trans-Equatorial Propagation. There may have been an extension at the northern end of the circuit with some marine tropo / ducting north of Cuba.
Mode of contact... The Q65B mode was used for this 144 MHz contact. The screen shot from LU7MC is shown below...
As you can see below, the signal level was about 0dB to -8dB which is probably too weak for SSB but should be strong enough to be heard by ear and a CW contact would be possible.
The screen shot from UT1FG/MM is shown below...
The signal levels were about the same at -4dB to -8dB.
Equipment... Carlos, LU7MC is located in the city of Mendoza in grid locator square FF57OB. He was running 100-watts into an array of 4 x 10-element Yagi antennas.
Yuri, UT1FG works on a commercial ship and was Maritime Mobile between Cuba and Florida in grid locator EL94PC. He was running 200-watts into a single 7-element Yagi antenna.
In conclusion... This really was an important contact on the 144 MHz band because it shows that there is a very good possibility of a TEP path from the west of Argentina to Florida. Could it extend even further north to some of the other southern US states by tropo? Could the stations in Chile get in on the action?
The really big question is if anyone in the United States is paying attention and is going to try and make a contact?
Link... a) For more information on long distance 2m contacts, see my 144 MHz page.
On the 7th of December 2024, PY1MHZ in Brazil and ZD7GWM on St Helena Island managed to complete a contact on the 144 MHz (2m) band. The distance was in the region of 3,770kms.
This was an amazing contact for tropo on 144 MHz and it raises the question if a contact from the east coast of Brazil to the west coast of Africa might be possible?
Marcos, PY1MHZ sent on the following information... "After many years of trying over the sea, a contact was finally made last night on 144MHz 2m with the Garry Mercury ZD7GWM on Santa Helena Island at a distance of 3,768km.
Contact completed with the Q65D mode
Garry was using a Diamond X700 vertical antenna and approximately 50w. On my side, I was using 8 vertical elements with 200w. I could work up to 500w but there was no need.
Very happy with this Christmas present. 73 de Marcos PY1MHZ in grid GG98LC."
Comment & Analysis... Yet again, this is another fine example of some of the undiscovered paths that exist once there are stations active in the right location. Some of the VHF contacts that Garry, ZD7GWM has been able to complete with a vertical omni-directional antenna are nothing short of remarkable.
In the last few years, he has managed to work South Africa at 3000kms on 144 MHz and 432 MHz via tropo, he has worked Spain and Portugal at about 6000kms on 144 MHz via TEP and now, he has worked across the South Atlantic on 144 MHz to Brazil.
As for the contact to Brazil, it seems likely that it was a marine duct across the South Atlantic. The tropo prediction map from Pascal, F5LEN certainly seems to support this theory.
How many other undiscovered long distance paths are out there?
Oguz, TA2STO in Türkiye has developed a new mode called LongChat to allow radio amateurs to communicate with each other.
It's described as follows... "LongChat is a low-power (QRP) / low bitrate text chat software application over ham radios connected to a PC. Chirp symbols with an audio bandwidth of 2400 Hz (300-2700 Hz) are generated on the PC side for encoding the messages. Baseband audio signal is then transferred from PC to ham radio for modulation at the selected mode. SSB, FM and other types of modulation modes can be used. Forward error correction codes are used to correct messaging errors
Current version is tested on ICOM-7300 and YAESU FT991A radios. Other radios are supported but not tested yet. Future improved versions will support higher data rates or lower S/N ratios.
Since the software is continually improved and data structures may have changed, newest version needs to be used for compatibility with all users. To ensure this, software will remind you to download and use the latest version when a new version is ready.
Specifications Usable data rate (net user data) is 7 ASCII characters per second at -12 dB signal to noise ratio. Eb/No (Energy per Bit to the Spectral Noise Density) is 5 db Measurement of received message SNR. Measurement of chirp frequency shift in SSB mode. You may download the software, user manual and brochure at the link below. https://drive.google.com/drive/folders/1NQwbeoHE3vPLORGN1krpSNHHI9brhDJh?usp=sharing "
As of late 2024, this is all very new and I'm sure a lot of people will have questions as to how good is it? Will it be better than modes like JS8Call? And more critically, will it get a critical mass of users to make it worthwhile?
I'd suggest that at the moment, it should be seen as something of interest to those who like to experiment with digital modes on the HF bands and want to experiment to see how it compares to other modes.
It also seems to be a 'work in progress' project but remember that the software for this mode is free and is being developed by one person. It'll be interesting to see how it develops.
TA2STO released the following video about it...
Update from TA2STO - 1st Dec 2024:
- Hi, I am the author of LongChat chirp mode. I started it a few years ago as a project for low power sensor applications. Then I wanted to try it as an experimental digital ham mode.
-LongChat is an encoder/ decoder. In general it should work on all modulations LSB, USB, FM, AM etc.
- I usually work with USB at lower band edges and LSB at upper band edge. It is easy to miss it when changing the modes. I guess I relied on IC7300 to disable transmission at band edges. IC 7300 does allow that though. I had no specific reason for using LSB. It works both on USB and LSB.
- I am preparing a new video to compare the power efficiencies of digital modes. I will post it when ready
- Newest version is 1.3.00 . Setup manual, version info and other things are also in the link above.
- LongChat is experimental and supports a number of radios. Untested radios are marked with * as the first character
- I am not an experience radio ham in operations and regulations. Maybe experienced radio hams can designate frequencies and protocols for test purposes.
- Since the signal is way below the noise level (-13 db) , there is yet no equivalent of a waterfall display like FT8, JS8 etc. This makes it harder to see the activity.
- You can view the waterfall in FT8 because it's minimum SNR is -4 db. and bandwidth is 50 hz . People quote -21 db as the SNR for FT8. This is the referred SNR if the bandwidth were to be widened to 2500 Hz. My next video will clarify these issues.
- Since there are no designated frequencies for LongChat, it is difficult to find some one for QSO
-There is also a criticism of LongChat not being open source . LongChat code has some new algorithms with IP value. If I open the source code to radio hams, people and companies with commercial interest will also have a free access. But I totally respect and mostly agree with the open source advocators.
- In short, LongChat is an experimental mode. My effort is to bring the SNR of LongChat to the limit dictated by the Shannon channel capacity theorem and make it the most power efficient mode.
- If people want to experiment with it, I am ready to support. I am not the best person to decide on the designated QSO frequencies, LSB or USB selection, protocols etc. If some of you want to do that , or perhaps open a group here or on google groups i.o, I would be happy to get involved.
Addendum: Matt, M0DQW released the following video which shows LongChat in operation...
Thanks to Rob, PE9PE for sending on this following news item. Omroep Venlo is a relatively low powered FM radio station in the south of the Netherlands running 0.5kW on 96.9 MHz.
On their site, they write... "Omroep Venlo was temporarily audible in Lapland thanks to a natural phenomenon. A local radio amateur in Northern Finland picked up the signal and listened to music from Venlo."
"52-year-old Marko Brask from Ivalo, Finland, some 2,300 kilometres north of Venlo, was surfing the airwaves when he came across a radio broadcast from Omroep Venlo. Brask could understand little of the song Waat Gaon We Doon by De Herfshane Band. Reason for him to write to Omroep Venlo and check whether the broadcast actually came from Venlo."
"That was correct; the fragment that Brask sent along is indeed from a broadcast of Omroep Venlo. The signal could be heard in Lapland thanks to a natural phenomenon with the ionosphere. This layer in the atmosphere can reflect radio signals back to the earth like a mirror. This allows signals on the FM band to be listened to over great distances."
They don't mention the date of the reception report but it sound likes it might have been Sporadic-E. The distance was 2236 kms which is just inside the maximum distance for one hop Sporadic-E.
Using Google search, I can see other reception reports for this person in Finland so it would seem like they are an experienced FM DXer rather than just some random person finding the station on an ordinary radio.
In itself, it's not all that special a reception report in terms of distance or power but it was still interesting to see a radio station acknowledge the report on their website.
In November of 2024, Carl, K9LA gave a presentation titled "Review of Propagation in the First Half of Cycle 25, and forecast for the Second Half of Solar Cycle 25" to the Madison DX Club. In it, he looks at the data for the current sunspot cycle, what the bands are like and what the future might hold.
It was also interesting to note from the presentation a recent interesting skewed propagation path on the 50 MHz band between the UK and Japan.
The main presentation is about 24-minutes in length.
Paul Logan in the north-west of Ireland is one of the most active FM DXers in Europe and on the 10th of Nov 2024, he caught an interesting opening on the 88-108 MHz band.
From about 11:00 to 12:00 UTC, he heard a large number of FM radio stations from Spain and Portugal due to a Sporadic-E opening. While this is quite normal during the summer Sporadic-E season, it is unusual during the month of November and especially at these frequencies.
However, the really interesting signals were those that were much further to the south. This is an extract from Paul's log...
Mode UTC QRGITUStation, location Distance km kW ERP Pol Es 120987.90 AZR RTP Antena 2, Pico Alto de Santa Maria 2346 1v Es 115193.00 CNR COPE, Puerto del Rosario/Temejereque 2906 4 Es 115488.60 CNR Happy FM, Puerto del Rosario/Temejereque 2906 0.25 Es 115291.20 CNR Onda Fuerteventura, Puerto del Rosario/Temejereque 2906 0.5 m Es 114987.70 CNR RNE Radio Clásica, Puerto del Rosario/Temejereque 2906 7 m Es 114690.20 MRC SNRT Al Idaâ Al-Watania, Tarfaya 2960 4v Es 114693.90 MRC SNRT Al Idaâ Al-Watania, Laâyoune=El Aaiún 3050 3.16 v Es 114691.00 MRC SNRT Radio Régionale de Laâyoune, Laâyoune=El Aaiún 3050 10 h Es 114687.90 MRC SNRT Al Idaâ Al Amazighia, Laâyoune=El Aaiún 3050 10 h
Note that the signals are in the lower portion of the 88-108 MHz band and the highest frequency listed is 93.9 MHz.
For this opening, Paul was using a SDR Play RSP1A receiver with a 9-element Yagi for Band 2.
The normal maximum range of single hop Sporadic-E signals is about 2300 kms so an explanation is required as to how the signals above were heard.
The image above shows the tropo forecast by Pascal, F5LEN showing enhanced conditions to the north of the Azores and Canary Islands.
It seems likely that while there was a Sporadic-E opening from Ireland to Spain and Portugal, this very likely extended to the west as well to the sea to the west of Portugal. This then coupled into a maritime surface tropo duct as far as the Azores, Canary Island and the Western Sahara / Morocco.
Of course, no-one can say for certain that this is exactly what happened. There is always the possibility of two Sporadic-E hops but the chances of that are a lot lower then the combined Sp-E / Tropo scenario.
Paul Logan as a very active FM DXer has heard stations in this area before but it's usually during the summer Sporadic-E season. It's just very unusual to hear 3000 kms signals in mid-November.
Indeed, Paul reports that this is the first time he has heard the Canary Islands by Sporadic-E outside of the usual summer season.
