UNID HFDL Like Signals 5-9 MHZ - Some with CW

[ultravista]

I regularly tune unknown data signals from 5-9 MHZ (possibly higher). It sounds like HDFL (bursts of uniform 'hiss') that may or may not include anything other that the bursts.

I have found a few have CW either before or after, can't tell which, but probably at the end of the transmission.

The waterfall pattern width is about as wide as  HFDL or STANAG.

I have listened to the identified signals in the WIKI and can't narrow this down.

[Josh]

A recording, freq, and time would be helpful in narrowing it down.

[ultravista]

Josh, the frequencies vary. I do not find any Google matches for the frequencies either.

The few I heard this morning had CW before or after the transmission. Just a few seconds, probably an identifier.

In Las Vegas, NV, I find these signals day and night using an active mini-whip antenna.

I'll grab screenshots or a video next time.

[Token]

The frequencies may be many, but we still need a real freq to start with.  Your description fits dozens of signals, we have to have some way to narrow it down.

And audio, video (with audio), or IQ recordings, recordings are worth hundreds of typed words.

T!

[Josh]

The only thing I can imagine routinely has cw before some burst transmission are the various readio telephone companies that cater to ships at sea, like WLO and the rest.

They run a cw beacon between fsk id bursts as a channel marker.
http://www.shipcom.com/frequencies.html

That being said, these are all over the bands and hardly a signal the hf aficionado wouldn't recognise.

[ultravista]

The videos below are similar to some of the 'HFDL Like' signals. In addition to the freq's below, I tume them this evening at 8.321, 6.890, 6.663, 6250.5, 4949.5, and 4.720 KHZ.

6.890 KHZ - not much to see here but there is some activity.
https://youtu.be/PDz3Ca9Zp48

7970 KHZ - bursts followed by solid noise
https://youtu.be/ljFAixDImXk

7971 5 KHZ - in CW mode
https://youtu.be/w5wOrLgcNPw

7971 5 KHZ - in CW mode, you can see the CW near the end of the video
https://youtu.be/bQ71Fnz4zeY

What is the best way to also capture audio? I am tuning with a Yeasu FT-590 with a IF tap connected to an RSP2 for the waterfall display. The audio is out of the Yeasu. Turning up the volume on the Yeasu and using the laptop microphone doesn't produce a good sound - the microphone picks up every noise in the house, including a mantle clock ticking and me breathing.

[ultravista]

Another two ...
6890.5 KHZ
https://youtu.be/NUZoAVRFXr0

5.600 KHZ
https://youtu.be/cMRa4yN3UGw

[MDK2]

Usually with an RSP2 (and I imagine any SDR), it's good to have a virtual audio cable to help route the audio. I'm not sure what having a rig in the mix does, but if the sound is entering your PC at all, it can be routed with the help of a virtual audio cable.

Assuming that that's the case, I recommend screen capture software. I've been using bandicam, in spite of the mandatory watermark it places on all videos if you don't pony up for the full license. That captures both video and audio, which is then very easy to upload to youtube.

You have to use the audio settings within the programs to make sure it works. SDRplay has some videos and documentation for installing and configuring a virtual audio cable, but it's pretty intuitive if you're comfortable with software.

[ultravista]

I swear this sounds like HFDL at the beginning, bursts of 'hiss'. HFDL however is on published/fixed frequencies where these appear to be random. Kind of like the HF 'pips' that randomly appear across the dial. I wonder if the two are related ... they seem to be in the same RF space.

What perplexes me is the CW at the end of some. I don't know morse to translate it but it must be an identifier. Maybe amateur outside of the US?

[Token]

7970 KHZ - bursts followed by solid noise
https://youtu.be/ljFAixDImXk

This specific signal is PACTOR IV.  Tentative to my own receptions to confirm, based on your frequencies and descriptions I think possibly you are hearing multiple sources / signals, some may be MARS nets, they will use various digital modes, voice, and CW.

That ID is VERY tentative though, just a first guess based on the videos.  And like I said, I thinnk you have more than one signal/source here, one signal looks a bit like a Chinese mode.

T!

[Josh]

Yep, what Token said, P4 mode. It sounds like hfdl because both employ psk modulation for the data bits, and I supose that like the doppler tone in hfdl, P4 uses the sweeping tones for doppler equalisation. No inexpensive decoders for P4 that I know of, but looking at udxf logs might point to a likely source.

Also, you tuned a bit off by a few hundred Hertz, when trying to id a sig, allow some slack from each side of a given sig so you get all of it inside the filter passband. That way we have all of it to work with rather than just 5/8s.