Communications mode?
While monitoring 10-meters this morning, I observed this on the spectrum display with SDR Console -- random longwire antenna through a 9:1 unun feeding an AirSpy Discovery HF+. The signal appears to be centered on 28600 kHz, with a modulation width of ±40 kHz (i.e., 28560 to 28640 kHz). I have not observed this before, and the pattern has been repeating for the past hour. Does anyone have any insights as to what communications mode this is?
I've observed some of the wideband stock-trading signals on lower frequencies, but shis looks and sounds different. Thanks in advance for any ideas.
Ken -- WBØOCV
While monitoring 10-meters this morning, I observed this on the spectrum display with SDR Console
Sorry Ken, I don't have time to look through myself, but have a look here for ideas:
https://www.sigidwiki.com/wiki/Category:HF
73
Max
Thanks for the suggestion, Max. I did scan through the sigidwiki examples, but didn’t find anything that matched the alternating/repeating forms of modulation which spanned an 80-kHz bandwidth. I’ll admit that those sections that appeared to be more “filled in” on the spectrum look somewhat like the broader ‘stock exchange trading’ signals I have seen before in other portions of the HF spectrum, but in my experience those have signals been constant over tens-of-minutes in duration, and often spanning several hundred kHz in bandwidth.
The alternating patterns of modulation I saw this morning are something I haven’t seen before. If I observe this again, I’ll try to at least capture an audio sample is SSB, DSB, and NFM modes, or even better a segment of IF or baseband recording.
Regardless, thanks for the suggestion to check sigidwiki.
Ken – WBØOCV
Sent: Wednesday, November 2, 2022 12:22 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Communications mode?
On Wed, Nov 2, 2022 at 02:37 PM, Ken Sejkora wrote:
While monitoring 10-meters this morning, I observed this on the spectrum display with SDR Console
Sorry Ken, I don't have time to look through myself, but have a look here for ideas:
https://www.sigidwiki.com/wiki/Category:HF
73
Max
Thanks Peter. It very well could be some OTHR mode, although none of the examples on sigidwiki mathch the alternating pattern of modulation. The closest match I saw was the US Navy ROTHR. The Iranian Ghadir OTH and RAF Pluto II OTH from Cyprus examples show different modulation and bandwidth. Granted, those examples on the sigidwiki site are just snapshots, and probably not representative of all of the possibilities of a given mode.
Have a great day – Ken
Sent: Wednesday, November 2, 2022 12:40 PM
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Communications mode?
Hello Ken this looks like OTHR (Over The Horizon Radar) The ones I have received are from Cyprus and Iran
Peter
I hope reading the material at the following link will shed light on this "mystery".
73
Danila (KarapuZ)
Appears to be another one centered on 29.000 MHz as well.
Kriss KA1GJU
It occurs to me that a talented programmer could toss off a really quick diddly to record the signal and broadcast it back out exactly one received pulse late with some clever amplitude distortions designed to make it look interesting.
{^_-}
Hi
I hope reading the material at the following link will shed light on this "mystery".
73
Danila (KarapuZ)
пт, 4 нояб. 2022 г. в 15:57, Kriss Kliegle KA1GJU <kliegle@...>:
Appears to be another one centered on 29.000 MHz as well.
Kriss KA1GJU
On Nov 4, 2022, at 5:04 PM, jdow <jdow@...> wrote:
It occurs to me that a talented programmer could toss off a really quick diddly to record the signal and broadcast it back out exactly one received pulse late with some clever amplitude distortions designed to make it look interesting.
{^_-}
On 20221104 09:56:39, данила фадеев wrote:
Hi
I hope reading the material at the following link will shed light on this "mystery".
73
Danila (KarapuZ)
пт, 4 нояб. 2022 г. в 15:57, Kriss Kliegle KA1GJU <kliegle@...>:
Appears to be another one centered on 29.000 MHz as well.
Kriss KA1GJU
I do wonder if they are setup to be protected from repeater
jammers. BUT, it'd be fun for somebody with a solid kW transmitter
on 10 to play with. I get "upset" when ham exclusive frequencies
are threatened.
{^_-}
Leave it to the pros. They’ve been doing it for decades.
Cheers,
George
On Nov 4, 2022, at 5:04 PM, jdow <jdow@...> wrote:
It occurs to me that a talented programmer could toss off a really quick diddly to record the signal and broadcast it back out exactly one received pulse late with some clever amplitude distortions designed to make it look interesting.
{^_-}
On 20221104 09:56:39, данила фадеев wrote:
Hi
I hope reading the material at the following link will shed light on this "mystery".
73
Danila (KarapuZ)
пт, 4 нояб. 2022 г. в 15:57, Kriss Kliegle KA1GJU <kliegle@...>:
Appears to be another one centered on 29.000 MHz as well.
Kriss KA1GJU