Amateur radio related things
This page is likely to be moved to QSL.net once I've obtained a proper license and a QSL.net account.
I've decided to learn about ham radio, mainly due to the fact that I plan to learn how to operate a boat and I believe having knowledge about operating a radio station could come in handy. On 2025.3.2 I visited a local radio museum; a few days later I ordered the RTL-SDR Blog v4 starter kit, which arrived after about 3 weeks.
I've been trying a lot of stuff ever since. Things I've achieved as of now (2025.4.3) are as follows:
- Listening to other people's Morse code & voice message
- Listening to shortwave radio
- Receiving DWD RTTY weather broadcast
- Decoding FT8* (*: Not sure. See below.)
- Receiving DWD and Northwood's WEFAX
- Receiving other people's SSTV
- Receiving some people's spectrum painting
- (2025.4.20) Tracking vessel location with AIS
- (2025.4.20) Tracking flights with ADS-B
- (2025.4.22) Detecting NFC activities
- (2025.4.22) Listening to DAB
- (2025.4.27) Receiving image from NOAA satellites
- (2025.5.9) Receiving SSTV from ISS
- (2025.5.27) Hearing conversations on aircraft band
- (2025.5.27) Decoding PACKET from satellites
Things I'm planning to do:
- Pass the required tests and obtain a proper CEPT Class 1 license (of course).
- (2025.5.27) I've passed the theory test; now I only need a Morse code test to obtain a CEPT Class 1 license here. Unfortunately whatever I've achieved here cannot be used in China (should the most unfortunate thing of me having to go back to China happens).
- Make contact with people outside of Ireland.
- Maybe dabble in amateur television a little bit in the future.
Software used
I'm running Arch Linux on a ThinkPad.
- gqrx: The main one for finding signals.
- SDR# works on Linux; it's just that I've accustomed to gqrx's UI.
-
sdrangel: For AIS, ADS-B, DAB and APT.
- DAB actually works on sdrangel running on linux, it's just that it chose to not play the test broadcast by FailteDAB during my first attempt. (See below.)
- welle.io: For DAB.
- fldigi: For decoding RTTY and WEFAX.
- qsstv: For decoding SSTV.
- wsjt-x: For decoding FT8.
- qpwgraph: For routing audio signals between applications.
- It used to be able to have a "monitor" device with PulseAudio; I couldn't manage to make one with PipeWire. My opinion is that it's better to just use qpwgraph, with which you can easily re-route the output from gqrx from your headphones to whichever software you need to feed and save yourself from potential hearing damage.
Signal reception in general
Other than local FM broadcast I've barely heard anything from VHF; most of the activities I've been able to receive has been between 7MHz to 15MHz. My situation is not optimal; the most I'm able to do within my room is to poke the dipole antenna out of the window at an awkward angle. I've tried putting it indoor, which resulted in worse signals. I suspect this is exactly what people should've expected, but I shall explore more.
Fiddling with things like this reminded me of my father. After the TV stations in Canton City moved on to digital broadcasting (which requires a set-top box and (what should be) private keys distributed in the form of smart cards), he had been trying to find a way to receive satellite TV signals so that we won't have to pay for local cable TV. He did succeed and for a period we enjoyed a lot of foreign stations than we were technically not allowed to have (unregistered satellite TV receiving was and still is against the Chinese law. Some people I've seen on the Internet over the years said that under a capitalist society you'd have to pay for air if they're allowed to turn it into a commodity; this will never happen in a socialist/communist society because you'd simply be punished for having air without the party's agreement.) We later moved to a place where the locals have successfully rejected digital cable TV through means I don't know; and by the time they finally have to give in we simply weren't interested in TV broadcast anymore (I don't think we even had a functioning TV that isn't just a glorified monitor at this point. Doesn't matter because I no longer had a functioning family at this point either) because you can do pretty much everything (and with WebSDR.org, you can do all the things I've done so far using other people's equipment) over the Internet.
Now after everything that has happened, I somehow do feel like I would like to dig deeper in these kind of things which for whatever reasons is a thought that had never once came across my mind in my younger years (I used to only care about computers). Circumstances do be strange in the ways they can turn out to be.
2025.4.20: I have been able to hear voices at about 423 MHz. They don't sound like ham radio conversations, and they have a noticable Irish accent (which means it is indeed near where I set up the listening). I suppose it's some kind of license-free radio thing that I couldn't find the info about.
2025.4.27: Apparently it's business radio which you can registrate w/ ComReg, which would make sense since I do live near a few factory-looking buildings.
2025.5.27: This happened a few weeks before, but I listened long enough to determine that they're actually mostly bus drivers.
Morse code & voice messages
Receiving these two has been by far the easiest (and should be the easiest for pretty much everyone else as well), yet I never managed to make fldigi properly decode Morse code without generating garbage despite decoding RTTY signal from DWD was a success; while knowing Morse code isn't required for a license now in Ireland (and depending on where you live it may not be required for you as well), it would still be better to know than not to know. Voice messages are fiddly; with upper sideband mode (which is the mode with which most activities occur) you have to get the frequency just right before you can hear clearly what was spoken.
Weather report
RTTY signals can somehow get parsed as SSTV in qsstv with the right setting; there's an option labelled "Sensitivity" which one (as I myself have experienced) would want to set at "High" instead of "DX" which could process other type of signals into technically garbage output. I think that sometimes it's better to tell one what's possibly out there first before letting them on their way of discovering; the idle beacon text, which when fed to qsstv this way, produces a green-tinted image of a grid pattern which I indeed did mistake as part of an SSTV image. The frequency it occurs might have already indicated that it couldn't be SSTV due to related regulations but I didn't know any better.
After knowing that signal was indeed in RTTY, the decoding was fairly easy.
CQ CQ CQ DE DDK2 DDH7 DDK9 FREQUENCIES 4583 KHZ 7646 KHZ 10100.8 KHZ RYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRY CQ CQ CQ DE DDK2 DDH7 DDK9 FREQUENCIES 4583 KHZ 7646 KHZ 10100.8 KHZ RYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRY CQ CQ CQ DE DDK2 DDH7 DDK9 FREQUENCIES 4583 KHZ 7646 KHZ 10100.8 KHZ RYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRY ZCZC 582 WODL45 EDZW 032100 STRONG WIND, GALE AND STORM WARNINGS FOR SEA AREAS: GERMAN BIGHT, WESTERN AND SOUTHERN BALTIC. GERMAN BIGHT: NO WARNING. WESTERN BALTIC: NO WARNING. SOUTHERN BALTIC: NO WARNING. COASTAL AREA WARNINGS: STARKWIND-, STURM- UND ORKANWARNUNGEN FUER DEUTSCHE KUESTEN. NR. QWQ AMTLICHE AUFHEBUNG / MELDUNG DES SEEWETTERDIENSTES HAMBURG FUER DIE DEUTSCHE NORDSEEKUESTE HERAUSGEGEBEN AM MONTAG, DEN 31.03.2025 UM 05:55 UHR GZ FUER DIE DEUTSCHE NORDSEEKUESTE BESTEHT KEINE STARKWIND-, STURM- ODER ORKANWARNUNG. NR. QWT AMTLICHE AUFHEBUNG / MELDUNG DES SEEWETTERDIENSTES HAMBURG FUER DIE DEUTSCHE OSTSEEKUESTE HERAUSGEGEBEN AM MONTAG, DEN 31.03.2025 UM 07:40 UHR GZ FUER DIE DEUTSCHE OSTSEEKUESTE BESTEHT KEINE STARKWIND-, STURM- ODER ORKANWARNUNG. SEEWETTERDIENST HAMBURG NNNN ZCZC 583 FQEN70 EDZW 032000 WEATHER AND SEA BULLETIN FOR NORTH- AND BALTIC SEA ISSUED BY MARINE WEATHER SERVICE HAMBURG 03.04.2025, WP UTC: UNTIL SATURDAY MORNING IN THE FOLLOWING FORECAST AREAS STRONG WINDS ARE EXPECTED: VIKING SKAGERRAK SOUTHEASTERN BALTIC CENTRAL BALTIC NORTHERN BALTIC GULF OF RIGA ENGLISH CHANNEL WESTERN PART GENERAL SYNOPTIC SITUATION: AN EXTENSIVE HIGH 1035 CLOSE TO THE EAST OF ICELAND MOVES SLIGHTLY EASTWARDS. A BROAD RIDGE EXTENDING TO POLAND SWINGS SLIGHTLY SOUTH-WESTWARDS, WEAKENING. A DEEP DEPRESSION 985 KOLA PENINSULA MOVES TOWARDS NORTHERN RUSSIA. AN ASSOCIATED COLD FRONT MOVES SOUTH-EASTWARDS FROM CENTRAL SWEDEN. AN EXTENSIVE LOW 990 WEST OF THE ALGARVE MOVES NORTH-EASTWARDS, WEAKENING. FORECAST VALID UNTIL SATURDAY MORNING: ENGLISH CHANNEL WESTERN PART : FIRST SOUTHEAST 3 TO 4, OTHERWISE EAST TO NORTHEAST INCREASING 5 TO 6, FIRST MISTY, SEA INCREASING 2,5 METER. ENGLISH CHANNEL EASTERN PART : FIRST LIGHT AND VARIABLE WINDS, OTHERWISE EAST TO NORTHEAST INCREASING ABOUT 5, FIRST MISTY, SEA INCREASING 2 METER. IJSSELMEER : FIRST LIGHT AND VARIABLE WINDS, OTHERWISE NORTHEAST INCREASING 4, SEA INCREASING 1 METER. GERMAN BIGHT : LIGHT AND VARIABLE WINDS, SHIFTING NORTH TO NORTHEAST AND INCREASING 4 TO 5, IN THE NIGHT MISTY, SEA INCREASING 2 METER. SOUTHWESTERN NORTH SEA : EAST TO NORTHEAST 3 TO 4, INCREASING 5, SEA INCREASING 1,5 METER. FISHER : NORTHWEST 4 TO 5, SHIFTING FAST NORTHEAST, SHIFTING EAST LATER, SEA FOR A TIME 2,5 METER.
Listing 1. Sample broadcast from DWD via RTTY with idle beacon text at the front.
NNNN ZCZC 584 FQEN75 EDZW 031800 WEATHER AND SEA BULLETIN FOR NORWEGIAN SEA AND BALTIC SEA ISSUED BY MARINE WEATHER SERVICE HAMBURG 03.04.25, QW UTC: GENERAL SYNOPTIC SITUATION: AN EXTENSIVE HIGH 1035 CLOSE TO THE EAST OF ICELAND IS MOVING SOMEWHAT TO THE EAST. A BROAD RIDGE EXTENDING TO POLAND IS SLIGHTLY SHIFTING SOUTHWESTWARDS WHILE WEAKENING. A DEEP LOW 984 NEAR THE LOFOTEN ISLANDS IS MOVING TO NORTHERN RUSSIA WHILE WEAKENING. AN ASSOCIATED COLD FRONT IS MOVING SOUTHWARDS ACROSS THE BALTIC SEA. AN EXTENSIVE LOW 989 WEST OF PORTUGAL IS MOVING NORTHEASTWARDS WHILE WEAKENING. DWD FORECAST OF TH/03/04.2025 QW UTC: WIND FORCE: BEAUFORT, WAVE HEIGHT: METRE NORTH CAPE (72.1N 25.3E) SST: T C FR 4. PPZ: N-NE 5-6 UAI RMT M // FR 4. PYZ: N 5-6 YAU EMT M SH // FR 4. QWZ: N 5-6 YAU E M // FR 4. QIZ: N 4-5 E M // SA 5. PPZ: N 4-5 WMT M // SA 5. PYZ: N 4 WMT M SH // SA 5. QWZ: SW 0-2 W M SH // LOFOTEN (68.6N 14.1E) SST: Y C FR 4. PPZ: N 6 I TMT M // FR 4. PYZ: NW-N 2-3 EMT M SNOW // FR 4. QWZ: N 0-2 E M SH // FR 4. QIZ: NW-N 4-5 WMT M // SA 5. PPZ: NW-N 4-5 W M // SA 5. PYZ: NW 3 W M // SA 5. QWZ: S 4-5 QMT M RAIN // HALTENBANK (65.5N 8.6E) SST: I C FR 4. PPZ: NW-N 5-6 U TMT M SH // FR 4. PYZ: NW-N 5-6 U RMT M // FR 4. QWZ: NW 6 I R M SH // FR 4. QIZ: N 4-5 YAU E M // SA 5. PPZ: NW-N 4 WMT M // SA 5. PYZ: NW-N 3-4 W M RAIN // SA 5. QWZ: W-NW 5 W M // SVINOY (62.3N 4.4E) SST: U C FR 4. PPZ: N-NE 4-5 EMT M // FR 4. PYZ: N-NE 4-5 EMT M // FR 4. QWZ: N-NE 4-5 E M // FR 4. QIZ: N-NE 5 WMT M // SA 5. PPZ: N-NE 4-5 W M // SA 5. PYZ: N-NE 4 W M // SA 5. QWZ: N-NE 3-4 W M // FAEROES (60.4N 5.6W) SST: O C FR 4. PPZ: E 5 YAU WMT M // FR 4. PYZ: E 5 YAU WMT M // FR 4. QWZ: E-SE 5 WMT M // FR 4. QIZ: E-SE 5 WMT M // SA 5. PPZ: E-SE 4-5 WMT M // SA 5. PYZ: E-SE 4-5 W M // SA 5. QWZ: SE 4-5 W M // PENTLAND FIRTH (59.7N 3.1W) SST: O C FR 4. PPZ: E 5 W M // FR 4. PYZ: E 4-5 WMT M // FR 4. QWZ: E 4-5 WMT M // FR 4. QIZ: E 4-5 WMT M // SA 5. PPZ: E 4 W M // SA 5. PYZ: E 4 W M // SA 5. QWZ: E 4 W M // HEBRIDES (57.9N 8.1W) SST: O C FR 4. PPZ: NE-E 4 W M // FR 4. PYZ: E 3 W M // FR 4. QWZ: E 3 W M // FR 4. QIZ: NE-E 2-3 W M // SA 5. PPZ: E 2-3 QMT M // SA 5. PYZ: E-SE 2-3 QMT M // SA 5. QWZ: E 2-3 QMT M // SHETLANDS (60.9N 1.6W) SST: O C FR 4. PPZ: NE-E 4 WMT M // FR 4. PYZ: NE 4-5 E M // FR 4. QWZ: NE-E 4 WMT M // FR 4. QIZ: NE-E 4 WMT M // SA 5. PPZ: NE-E 3-4 W M // SA 5. PYZ: NE-E 3-4 W M // SA 5. QWZ: NE-E 3-4 QMT M //
Listing 2. Sample broadcast from DWD via RTTY.
The schedule I find from DWD online claims that they broadcast 24 hours a day; possibly due to weather conditions there are times (which randomly occurs during the day) when I can't manage to get a signal at all; I never managed to get anything from both DWD and Northwood below 7MHz.
Figure 1. Image received from DWD, converted to 1-bit palette w/ dithering using GIMP 3.
After successfully receiving WEFAX from DWD I was able to receive WEFAX from Northwood as well with a little bit of struggling.
Figure 2. Image received from Northwood, restricted to a 3-color palette w/ dithering using GIMP 3.
SSTV
I've managed to receive other people's SSTV on 14230 KHz. You kinda have to be lucky because there had been days where nothing's on the frequency.
Figure 3. The first two images received when I realized there's SSTV activities happening on 14230 KHz. Image restricted to a palette of maximum 255 colors using GIMP 3.
Figure 2. Image received from the same setup that I can read the callsign from. Restricted to a maximum 255-color palette using GIMP 3.
It never fails to amaze me the fact that most activities I've been able to know is, again, from Italy, which is thousands of kilometers away from Dublin.
2025.5.9: I now have a different place for some of the SSTV images I've received: https://www.geocities.ws/bctnry/ here. I may upload some of the image I've received there.
FT8
FT8 can be loudly heard on 30m and the 20m band here; they show up as thin wiggly lines on the waterfall graph (compare with electronic inteference, which are thick wiggly lines). I was using wsjt-x and message shows up in bundle instead of one single message at a time, and to be honest I have no idea if I've done this correctly or it's just outputting garbage like my previous attempt at decoding CW with fldigi.
I can see why some people don't like FT8. It do suck the joy of knowing that there's another person on the other end when everything is this automated.
What happens on a bad day
By the time I'm writing this (2025.4.4) it was said that the sun would be more active which would disturb the Earth's magnetic field more, both of which was said to have an adverse effect on receiving signals on the HF band. I certainly didn't expect you'll have to care about solar activities as well. I definitely can feel a decrease of activities today - there's barely anyone (well, barely anyone I could hear) in 20m.
I managed to grab one WEFAX from DWD before deciding to wait until the space weather become good enough again, but the result is very blurry, which I suppose would be barely of any use (if at all) except for demonstrative purposes.
Figure 4. Image received from DWD, this time the quality is bad.
Figure 5. The same kind of image, received in better conditions.
Spectrum painting
I don't think a lot of people do this because I suppose it's not a very "legitimate" way of using radio, but I'm lucky enough to have captured an instance of it.
Figure 6. Spectrum painting, presumably by K3SSG.
AIS & ADS-B
I got to know about this by courtesy of blinry.
AIS stands for "Automatic Identification System", and is used to track vessels. ADS-B stands for "Automatic Dependent Surveillance - Broadcast", and is used to track aircrafts. I couldn't manage to get anything that's far away; basically the city bound is the limit. I suppose it makes sense since AIS is in VHF and ADS-B UHF.
Figure 7. Screenshot of tracking vessels using sdrangel.Figure 8. Screenshot of tracking aircrafts using sdrangel.
NFC
I happened to stumble on this around 13.560 MHz while searching through HF range for AM radio broadcast. It showed up very loud on the thingy probably because I was sitting close to my antenna. I should probably learn GNU Radio and learn how to decode it someday...
Figure 9. Screenshot of NFC signal under gqrx.DAB
It was said that RTE stopped offering DAB in 2021 and after that there's no DAB in this country, until a trial that has started since earlier this year by FáilteDAB, so I suppose had I discovered about DAB earlier I wouldn't have suceeded in receiving it. Well, whatever success I've had with DAB definitely don't feel like a success either - currently the trial was said to only consist of a single test tone and nothing else, which was exactly what I received (titled "mac tire").
2025.4.23: I tried this again today and I was able to receive signals for ~20 channels at DAB channel 7C (192.352 MHz). I clearly saw something at channel 10D (215.072 MHz) but sdrangel wasn't able to decode it.
NOAA
Finally I've captured a discernable image from a NOAA satellite (NOAA-18). With less-than-favourable conditions as well - I didn't even stick the dipole antenna out of the opened window, but somehow there were brief periods of time when the signal-to-noise ratio was large enough. Propagation surely is a strange thing... The white patches (on the left side) are definitely clouds instead of noise because they're too "togethery". Before this I've basically given up NOAA at this point so I can't say it isn't a nice surprise.
Figure 10. Captured image from NOAA-18, restricted to 8 colors w/ GIMP. (Click the image for larger version)
ISS
The signal is surprisingly detectable at 145.800 MHz (NFM), it's just that it's only there for a couple minutes at a time. I thought they stopped doing this before, until I've seen someone posted what he had received from ISS to Reddit. It's a shame that currently it's with very big very obvious communist things, but one is recommended to try to see if there's anything out there when ISS goes pass your local sky.
Figure 11. Captured image from ISS, restricted to Web Safe palette w/ GIMP.
Airband conversations
You can turn on labels for frequencies in gqrx, and when you scrolling through the frequencies you can see which purpose is which frequency supposed to have. I've discovered about airband this way and have heard conversations in the frequency range, but the signal is too weak and I could only be certain that there are people talking; I couldn't make out what's being said at all.
PACKET
gqrx comes with a 1200bps AFSK decoder; I've been able to make it decode messages when ISS flies across the sky here:
18:54:33$ fm DL7NDR-0 to JN48AP-0 via RS0ISS-0 UI PID=F0
:EA3DNC :QSL?
18:54:38$ fm SQ3KAR-1 to UQSX54-0 via RS0ISS-0 UIv PID=F0
`-P.l .[/`_0
18:54:38$ fm RS0ISS-0 to 0P0PS5-0 via APRSAT-0 UIv PID=F0
'v&.l .SI]ARISS-International Space Station=
18:54:41$ fm SP6STG-1 to APU25N-0 via RS0ISS-0,WIDE1-1 UI^ PID=F0
=5106.69N/01657.39E-PHG-25309 - IGATE 8h*TM-D700* KISS TNC* {UIV32}
18:55:29$ fm SP3LOR-4 to APY400-0 via RS0ISS-0 UIv PID=F0
:ALL :via ISS SAT 73' Krzysztof Poznan qsl {74
18:55:35$ fm DL7NDR-0 to JN48AP-0 via RS0ISS-0 UI PID=F0
:SP3LOR-4 :QSL?
18:55:37$ fm SQ3KAR-1 to UQSX54-0 via RS0ISS-0 UIv PID=F0
`-P.l .[/`_0
18:56:05$ fm SP6STG-1 to APU25N-0 via RS0ISS-0,WIDE1-1 UI^ PID=F0
;SP6STG-L *201119z5106.69N/01657.39ErEchoLink SP6STG-L 118555 / 144.675/DTMF
18:56:07$ fm ON7KEI-0 to CQ-0 via RS0ISS-0,APRSAT-0,PCSAT-1,DP0SNX-0,AISAT-1,SONATE-0 UI^ PID=F0
=5001.87N/00523.97E-73' Via Satellite
18:56:11$ fm DL7NDR-0 to JN48AP-0 via RS0ISS-0 UI PID=F0
:SP6STG-1 :QSL?