AM sync lessens noise in this The Voice of Greece broadcast

TheParthenonAthensSometimes, the Voice of Greece plays very little Greek music; October 10th was one of those occasions.  Nonetheless, I recorded that evening’s broadcast.

Using AM sync for sideband noise

In the first hour of the 10/10 VOG broadcast, you’ll hear a pulsating noise from an unknown origin (possibly a jammer?). The noise was centered about 20 kHz above VOG.

Fortunately, most of the noise was in the upper side band of the VOG signal, so I was able to mitigate it by using an AM sync lock on the lower side band. Without AM sync, this VOG broadcast––and its music mix––was almost inaudible.

If you have a synchronous detector on your receiver and tune in a station with interference, always try turning on sync lock and locking it on either the upper or lower sideband. If most of the noise resides in one of the sidebands, the lock can help tremendously. I often use this method while listening to AM pirate radio stations in noisy conditions.

A confession…

I have no idea what she’s talking about–it could be something absolutely mundane–but I love this radio host’s voice as she speaks and Pink Floyd’s Comfortably Numb begins(Start listening around 26:00)

Click here to download more than two hours of the Voice of Greece, recorded on October 10, 2013, starting around 03:15 UTC on 9,420 kHz, or simply listen via the embedded player below. Most of the noise disappears around 00:21:

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4 thoughts on “AM sync lessens noise in this The Voice of Greece broadcast


    First to note that we have no observations from Greece, but from Germany and Cyprus. I think it is hard to get ERA5 in Greece, probably due to the directed beam (correct me if I am wrong).

    We are still trying to find a pattern on what exactly is causing interference, because there are still some awkward observations. For example yesterday in Germany there was a super clear reception around 4:00am Greek time until the noise started again at 4:10am. This is a bit irregular.

    Fact is, that the CRI broadcasts many hours of the night at 9430 or 9435; that’s pretty tight, but not sure if this is the source. Because after the noise at 9420 started, ERA5 could still be heard at 9422 (but heavily distorted, like high frequencies were missing). First, I do not understand how the supposed side-interference from CRI 9430 can jam 9420 but leave a gap at 9422. Second, I am trying to match this from your observation, that the noise is centered higher at 9440(?), although in my case, the noise was a bit lower, and at 9422 was the gap where still ERA5 could go through.

    There is one more possibility that suggests that ERA5 is indeed being jammed; but the jamming occurs not on the shortwave, but on the radio link between the radio studios and the transmitter. Explanation: Indeed, after the ERT company got dissolved, the telecommunications authority suspended the leased lines that transfered audio to the radio and TV transmitters. So, the backup microwave links turned on for this purpose. There is a case that the radio links just get un-tuned because of technical problems or lack of personnel. But ERT engineers have in the past suggested an unknown source of interference by a mobile transmitter, disturbing the backup links. This is what was suggested by a twitter user who seems to be one of them, when we posed the problem.

    Therefore, from what we hear, could we say that the noise that we receive, is actually transmitted by the ERA5 transmitter itself, being fed with a mixture of an analog signal carrier and noise?

    1. Thomas Post author

      Most interesting. Thank you for the follow-up! I will check tonight and see if the noise is still there. I have spectrum recordings of VOG from Oct 21 and 22 as well.



    This issue with the reception of ERA5 abroad has been also noticed, but the signal clears out usually around 6am Greek time.

    It’s tempting to think that this is jamming effort. After all, this transmitter is still being operated by unpaid redundant employees of ERT who keep broadcasting full program as a protest against the a Greek government, awaiting a ruling of the high court. On the other side, the government doesn’t have the technical means for jamming, so we think this may be something else, e.g. a technical problem.

    1. Thomas Post author

      Yes, you’re right. The interference does end around that time. At least we know this noise can be heard in Greece as well.
      I didn’t think that the Voice of Greece was being jammed, rather, I assumed it was another broadcaster being jammed 20 or so kHz above 9420. I believe we were hearing the outer edges of that interference.
      Thanks for your comment!


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