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Utility Listening - Discussions regarding monitoring government, military, aircraft, ship, and other misc communications in the HF/MW/LF bands.

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Old 01-14-2018, 8:47 PM
Join Date: Jun 2010
Location: Mojave Desert, California, USA
Posts: 1,960
Default VC01, the Chinese Robot, transmitter changes in mid transmission


I put up a video today of Chinese oddity VC01, the Chinese Robot. There are lots of videos of VC01 on line, however this one shows a specific feature of VC01 that I have not seen other videos address. This is not new, VC01 has done it for years.

Occasionally you will hear VC01 make a noticeable change in its transmitted signal in mid transmission. The signal may abruptly change in signal strength, or it might shift frequency slightly, or maybe the transmitted bandwidth will change. It is easiest to notice when it does all 3 of these at the same time.

I have also noticed, using remote receivers, that sometimes a reduction in signal at my location correlates to an increase in signal at someplace else. Remember, this is not fading or conditions, it is instant, like throwing a switch.

It might make sense that they cycle through various antennas, and possibly transmission bearings, to insure coverage over a wider area. But to me, because of the sometimes associated frequency shifts and bandwidth changes, it clearly looks as if they are not only changing antennas, but maybe also changing transmitters.

This leads to a few questions in my mind. Could this be a distributed network of transmitters? If not distributed, why change transmitters but stay in the same mode on the same frequency?

Anyway, to the video. The video is made from recordings of two different receptions of VC01 at my location, more than a year apart. I have several other recordings showing similar activity, I just chose these two because the changes were fairly pronounced (many times it is harder to detect) and to show it was not a one time thing.

The cycle takes about 6 minutes to complete. Most of the time I have seen this it has taken about 6 minutes. To avoid a 40 minute video I have jumped ahead in time to show the changes and 10 seconds before and after each change.

The video is here:

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