23 November 2018

WINB Red Lion to test DRM Single Channel Simulcast (SCS)

(updated)
Shortwave station WINB has recently started conducting test in DRM directed to Europe on 15670 kHz Monday - Friday from 11:00 -17:00 UTC using a new DRM 18 Kw transmitter, an ASI CE-50000WS, and Rhombic antenna at 062 degrees, according to WINB’s own website. The signal can be received by several KiwiSDR receivers in Europe, as well as by the N4LGH KiwiSDR located in Florida which has the signal from the back of the beam (Fig. 1).
My friend F4MP "Zyg" emailed me kindly asking to take a look at those "combo" test signals, given that DRM  is only located in the upper 5 KHz sideband of the channel.

Fig.1 - my reception of WINB DRM tests from N4LGH KiwiSDR

Datacast rather than simulcast? 
As from ETSI TS-102-509 V1.1.1, strictly the term simulcast can be taken to describe a transmission allowing the simultaneous transmission of analogue and digital versions of the same audio programme in one frequency channel (Single Channel Simulcast, SCS). A simulcast signal signal consists of a sinusoidal carrier and two additional signal parts in the upper and lower sideband. The digital part in the upper sideband corresponds to a DRM signal, therefore a standard DRM consumer receiver will be able to extract and decode the included digital data. An analogue audio AM receiver applying envelope demodulation on the overall received signal will provide an audio signal to the listener comparable to standard AM transmission. [1] [2]
Clearly, that's not the case of WINB. Moreover, due to the fact that multipath propagation via the ionosphere is a typical characteristic of radio channels in HF broadcasting, the use of SCS is recommended only for LF and MF bands with mainly ground wave propagation.

So, what is carried by the lower sideband of the signal?
Nobody knows with certainty, at least at present when I'm writing this post. Interesting discussions on WINB DRM test transmissions can be read in the DRM Forum as well as in w4uvh site:
Oddly, on DRM Forum nobody associated with WINB has commented on the simul/datacasting although they have made several posts regarding the DRM broadcast.
 
Looking at FCC license for these tests we note the 10K00G9W emissions designator for the CE-50000WS transmitter beamed to north Europe (Fig. 2):

Fig. 2 - FCC license
10K00G9W designator means that WINB may transmit:
10 k = 10 kHz signal bandwidth
G = phase modulation
9 = Analog and digital channels
W = any combination of telegraphy, fax, data, telephony or video

so the license offers the chance to transmit digital signals or ordinary AM signals.
Analyzing the lower sideband of the signal I may count up to 78 unmodulated tones that could be MFSK as well as constructed using OFDM tecnology, in this case the tones have rotated phases. Likely it's a test/experimental transmission w/out data carried.
Fig. 3
Fig. 4
31 October update
I have a little but important update: some days ago I heard WINB DRM signal at my QTH on 13690 KHz, surely due to good propagation conditions. I twitted a little post and WINB answered asking a report about that reception. The most important fact is that they confirmed data transmission o the lower 5 KHz channel.


23 November update
First time, at least at my side, that I hear their emissions on 9265.0 KHz in the morning: a bit unusual band (30mt) since the time (0930 UTC). Maybe they are testing the "service" in different bands?



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