The Voice of Greece is an unpredictable broadcaster these days. VOG is not on the air as much as in the past and doesn’t seem to follow a broadcast schedule. I only hear them perhaps once or twice per week now.
I love VOG’s music programs and last night their Avlis transmitter was fired up and relaying some wonderful tunes.
The following recording was made on January 30, 2016 starting at 0145 UTC on 9420 kHz. I made this recording with the TitanSDR Pro receiver connected to a large skyloop antenna. Click here to download the MP3, or simply listen via the embedded player below:
I also had the TitanSDR simultaneously recording pirate radio spectrum just below the 40 meter ham band. I’m saving that bit of spectrum for a rainy day!
The lighter shaded side of the AM carrier indicates a lower sideband sync lock. (Click to enlarge)
A few days ago, I tuned to 9,420 kHz and found a relatively strong signal from the Avlis transmitter site of the Voice of Greece. The broadcast was quite clear until a heterodyne (het) tone popped up out of nowhere.
I checked the spectrum display of my Excalibur to find two steady carriers located about .5 kHz off each side of VOG’s AM carrier. I assume this may have been a faint digital signal centered on the same frequency as VOG.
The noise was annoying, but SDRs (and many tabletop radios) have tools to help mitigate this type of noise.
The het tone was originating from both sidebands of the VOG AM carrier (see spectrum display above). I had planned to use my notch filter to eliminate the noise, but I had two carriers to notch out and only one notch filter.
Synchronous detection to the rescue…
The simple solution was to eliminate one of the carriers using my SDR’s synchronous detector which can lock to either the upper or lower sideband. In this case, it didn’t make any difference which sideband I locked to because both had similar audio fidelity and were otherwise noise free. In the end, I locked to the lower sideband, thus eliminating the het in the upper sideband.
Next, I enabled my notch filter and moved its frequency to cover the annoying het carrier in the lower sideband; I kept the notch filter width as narrow as I could to preserve VOG’s audio fidelity. You can see the notch filter location and width in the spectrum display above (the notch filter is the thin yellow line).
I should note here that the great thing about using an SDR–or tabletop receiver with a spectrum display–is that you can see where the noise is. I was using my WinRadio Excalibur, but pretty much any SDR in my shack could have handled this task.
The results? No het tone and I was able to preserve the great audio fidelity from the Voice of Greece broadcast!
Here’s a 3.5 hour recording I made after cleaning up the signal. I believe at one point in the recording, I switched off the notch filter to demonstrate how loud the het tone was:
Early this morning, around 01:14 UTC, I tuned to 9,420 kHz with the Elad FDM-S2 and heard the Voice of Greece for the first time since the Greek national broadcaster, ERT had been restored.
SWLing Post contributor, Richard Langley, also noted the strong signal from Greece. He has kindly shared the following information which he also posted in the DXLD Yahoo group:
“Greece is back on 9420 kHz this evening after being absent for some days and is now carrying the Voice of Greece […] program and not ERT from Athens or Thessaloniki. Noted with good signals in eastern Canada at 01:40 UTC. Radio audio is about half a minute delayed with respect to Internet stream: […](http://www.ert.gr/i-foni-tis-elladas/?). Not noted on other frequencies.
[…]9420 kHz signed off just after [02:00] UTC. Internet stream continued. And I should correct myself when I mentioned “not ERT from Athens or Thessaloniki.” Should have said not ERA from Athens or Thessaloniki. ERA is the abbreviation for Hellenic Radio […], as opposed to ERT which stands for Hellenic Radio-Television […]. ERT1, ERT2, etc. are TV stations while ERA1, ERA2, etc. are radio stations. This is a bit like BB1, BBC2, …, and BBC Radio 1, BBC Radio 2, and so on.”
Richard followed up a few hours later:
“I continued listening to the Internet stream after the SW transmission ended, and at 02:57 UTC, the station identified itself in both Greek (“Edo Athina, I Foni Tis Elladas”) and English (“This is Athens. You are listening to the Voice of Greece”) several times, followed by the traditional interval signal and then what I believe to be the Greek national anthem at 03:00 UTC. A program of Greek music then ensued.”
Many thanks for sharing the details, Richard. My recording actually ended when VOG signed off–I suppose I caught about the last 46 minutes of the broadcast.
SWLing Post contributor, Ayar, confirms that ERT employees did indeed returned to work yesterday after having been laid off nearly two years ago. Ayar shares this link to GreekReporter.com which has full details.