Aircraft on 23184KHz LSB

[williamGB]

Today, I came across multiple signals around 23MHz.. 2 of which were Gander and Santa Maria.. but the modulation was LSB not USB.. is that normal? I thought HF aero is only on USB? The Gander frequency is 23184 and the Santa Maria 22172. I'm also hearing selcals on 23217, 23250, and 23202 (all LSB) but i was not able to make out the voices. I received these at around 5am in the UK.

William

Edit:
I heard an aircraft on 23202 with the callsign Turkish 904, I jumped on FR24, and the aircraft was over the Atlantic near Bermuda which makes 23202 New York Radio.

 

[williamGB]

Update: I hear aircraft saying "This is CALLSIGN calling Gander on 5616"... but im tuned to 23184. Is my SDR getting overwhelmed by the frequencies?

 

[sunwave]

Today, I came across multiple signals around 23MHz.. 2 of which were Gander and Santa Maria.. but the modulation was LSB not USB.. is that normal? I thought HF aero is only on USB? The Gander frequency is 23184 and the Santa Maria 22172. I'm also hearing selcals on 23217, 23250, and 23202 (all LSB) but i was not able to make out the voices. I received these at around 5am in the UK.

William

Edit:
I heard an aircraft on 23202 with the callsign Turkish 904, I jumped on FR24, and the aircraft was over the Atlantic near Bermuda which makes 23202 New York Radio.

That's a wild frequency to hear New York Radio at the hour of your OP. Post for me your RF gains and describe the antenna and which SDR you are using. Also, for your own frequency reference, ARINC has a daily list of active frequencies here Atlantic HF Assignments

If you are running any sort of LNA please provide that info too.

 

[williamGB]

That's a wild frequency to hear New York Radio at the hour of your OP. Post for me your RF gains and describe the antenna and which SDR you are using. Also, for your own frequency reference, ARINC has a daily list of active frequencies here Atlantic HF Assig

My RF gain is actually 0 haha, and the antenna is a 20m dipole in a V shape made from some old copper wire connected to a noolec balun one nine. I tend to receive New York and Gander around midnight to around midday, then I get Shanwick and Santa Maria from early morning to night time. I actually made my own list with the general time I checked the frequency and I heard something.

ATC Centre	Frequency	General reception time	ATC Centre	Frequency	General reception time
Dakar	6535	01:10, 02:15	Gander	5598	00:00
Gander	3476	09:23	New York	5598	01:40, 04:30, 06:15, 07:00
Gander	5616	00:25, 01:40, 03:10, 04:30, 06:15, 07:55, 09:30	Santa Maria	5598	01:30, 03:10, 04:30, 07:45
Gander	8891	09:25
Gander	11279	13:30, 16:30
New York	5505	04:30
New York	5520	00:30, 01:40
New York	5550	00:30, 01:40, 03:10, 04:30
New York	6577	02:30
New York	6586	02:05
New York	8893	00:35
New York	8906	04:00, 05:30
Pacific	5547	03:10, 04:30, 06:35
Santa Maria	6628	04:35, 06:40
Santa Maria	8906	09:40
Shanwick	3491	06:45
Shanwick	4651	06:45
Shanwick	5583	04:20, 09:30
Shanwick	5649	08:10, 09:30, 13:20
Shanwick	5803	06:05, 08:10
Shanwick	6622	09:30
Shanwick	8879	13:30

 

[sunwave]

My RF gain is actually 0 haha, and the antenna is a 20m dipole in a V shape made from some old copper wire connected to a noolec balun one nine. I tend to receive New York and Gander around midnight to around midday, then I get Shanwick and Santa Maria from early morning to night time. I actually made my own list with the general time I checked the frequency and I heard something.

ATC Centre	Frequency	General reception time	ATC Centre	Frequency	General reception time
Dakar	6535	01:10, 02:15	Gander	5598	00:00
Gander	3476	09:23	New York	5598	01:40, 04:30, 06:15, 07:00
Gander	5616	00:25, 01:40, 03:10, 04:30, 06:15, 07:55, 09:30	Santa Maria	5598	01:30, 03:10, 04:30, 07:45
Gander	8891	09:25
Gander	11279	13:30, 16:30
New York	5505	04:30
New York	5520	00:30, 01:40
New York	5550	00:30, 01:40, 03:10, 04:30
New York	6577	02:30
New York	6586	02:05
New York	8893	00:35
New York	8906	04:00, 05:30
Pacific	5547	03:10, 04:30, 06:35
Santa Maria	6628	04:35, 06:40
Santa Maria	8906	09:40
Shanwick	3491	06:45
Shanwick	4651	06:45
Shanwick	5583	04:20, 09:30
Shanwick	5649	08:10, 09:30, 13:20
Shanwick	5803	06:05, 08:10
Shanwick	6622	09:30
Shanwick	8879	13:30

I am guessing a RTL-SDR if so, which variant?

 

[williamGB]

I am guessing a RTL-SDR if so, which variant?

I'm using the Nooelec v5.

 

[sunwave]

I'm using the Nooelec v5.

Okay aliasing is the big problem from overload. Your situation warrants adding an attenuator of lets say 20db. A variable attenuator. It is common that people use an attenuator to knock off the signal to stop the overloading. Nooelec v5 uses the Q branch which disables RF gain. With the RF Gain disabled it's cramming everything down the pipe.

Essentially, your antenna is very very good at receiving signals but it is too strong for your v5. Keep your antenna inline and get yourself a nice variable 20db attenuator. That should solve it.

 

[williamGB]

Okay aliasing is the big problem from overload. Your situation warrants adding an attenuator of lets say 20db. A variable attenuator. It is common that people use an attenuator to knock off the signal to stop the overloading. Nooelec v5 uses the Q branch which disables RF gain. With the RF Gain disabled it's cramming everything down the pipe.

Essentially, your antenna is very very good at receiving signals but it is too strong for your v5. Keep your antenna inline and get yourself a nice variable 20db attenuator. That should solve it.

Ahh i see. I'll definitely get an attenuator! Thanks for your help!

 

[sunwave]

Ahh i see. I'll definitely get an attenuator! Thanks for your help!

you're welcome. I wanted to also recommend the rtl-sdr.com v4. It doesn't use the Q branch. It uses a built-in ring mixer upconverter in quadrature sampling which gives you RF Gain control and no nyquist folding. Attenuators might be expensive, so, If an attenuator is more than $29.99 then get the v4. That's how I would do it. My v4 won't overload like the v3 when RF Gain is properly set. The v4 without the antenna kit is $29.99 on Amazon while in stock.

Will will have to replace the rtlsdr dll in the software you use if you do get the v4. SDR sharp v1919 has the install.bat that will take care of that for you only in sdr sharp.

Latest beta of sdr-console already has v4 dll driver

HDSDR needs a different EXTIO dll for the v4

DSDPlus FL needs the updated dll from base files and new FMP24

 

[radar_hunter]

All RTL-SDRs that use the direct sampling mod and not a built-in upconverter will alias the HF spectrum around 14400 kHz. This is not overloading and an attenuator will not help. A low/high pass filter at 14400 kHz would help but the RTL-SDR blog v4 is probably more convenient as a low-cost solution with better HF capabilities.

(14400-5616)+14400 = 23184 so that's why you hear it on the wrong frequency.


Overloading and imaging problems can also occur with the RTL-SDR but they are different problems. For example, FM broadcast interference can be pretty bad on 27 MHz in the normal operation mode, and the solution is an FM band stop filter.

 

[williamGB]

Ahh that makes sense. I was getting a radio station on the CB band, but it's actually broadcasting on 1458!