Radiofax: XSG Shanghai, China (National Meterological Centre, CMA)

Just when I thought my series on radiofax may well be drawing to a close, a reader by the name of Vitor (ONL12294) contributed some very valuable information leading to Shanghai Coast Radio (XSG) Faxes. Armed with a set of frequencies, I went on the hunt using my modified kiwifax.py with a few strategically located receivers and struck gold nearly immediately. Rather than tell the whole story upfront – I’ll do the narrating with the faxes instead.

The faxes presented below are a “snapshot” in time and are not kept up to date. They should not be used for navigation purposes. Please note that the copyright in the faxed material is believed to belong to the originating agency – the National Meteorological Center or Shanghai Meteorological Bureau (CMA); or the transmitting agency – Shanghai Coast Radio Station (XSG). Faxes are reproduced for the purposes of documentary, to illustrate the technical characteristics of the fax transmission, to illustrate the formatting of the content within these transmissions and as proof of activity of the station, propagation and reception at the times, frequencies and locations given.

Faxes

Given the list of frequencies to try including 4170kHz, 8302kHz, 12382kHz (known working) and 16559kHz, I went straight to hunting mode to try and capture the signal. As I was up early, I set up my monitoring on the Chongqing, China and Shenyang, China SDRs on both 8302kHz and 12382kHz as the frequencies I felt were most promising in the hopes of catching something.

Almost immediately, I was rewarded at 0000UTC with the schedule – so I knew the system was alive. It helps to know when a transmission is running, as then we can seek other potential reception candidate sites. Looking about, Japan, South Korea and Hong Kong had relatively strong signals. Weaker signals were seen in Vietnam and India. The signal didn’t seem to reach much further than this – probably due to a combination of propagation effects at the transmission time, the transmission power and antenna used.

From my discovery, I was able to hear the system on all frequencies but only weakly on 4170kHz. The remaining frequencies were able to produce decodable results depending on propagation and time of day. I set to monitor the system over the next four days (3rd March 2019 through to 6th March 2019) to collect decent quality examples of the charts without burdening too many KiwiSDRs for too long.

The best reception was from JH1PGF in Japan which managed an S9+10 to S9+30 signal from XSG. Congratulations on an excellent reception set-up! Unfortunately, there is a 24-hour time limit of just two hours, thus I could not rely on it to collect all faxes without trying over several days and guessing and hoping I chose the right frequency. JE1AHJ in Japan was second best, with S7-S9 most of the time and no receiver time limits. Oddly enough, it seemed that the Shenyang and Chongqing SDRs in China suffered from high noise floor, thus often produced much worse decodes.

The following faxes will be shown along with the date, reception time, frequency and receiver used. Thanks goes out to all the public KiwiSDRs named (as well as some that are not) for their involuntary involvement in the project.

System-Related

The most important chart of the (UTC) day is the broadcast schedule, sent at 0000UTC, the above example was received on 8302kHz on 4th March 2019 via Shenyang SDR. The schedule illustrates many of the important transmission characteristics common to XSG charts including white tuning tone preceding the chart, WMO start/stop tones, a phasing area that’s almost 50/50 black and white (unique to XSG) and trailing black tone with black image margins.

From the line-up on the schedule, local time is first in the column with UTC in brackets (which is also slightly unusual). The charts are given an alphanumeric designation similar to the JMH/HLL2 charts. The schedule is dated 1st September 2018 and all charts are sent only once a day with the exception of the tropical cyclone forecast. The frequencies are shown in the footer, with the transmission identified as from Shanghai Coast Radio Station and Shanghai Meteorological Bureau/CMA.

Charts

Charts will be presented in order of the transmission schedule, examples are the best quality received within the four monitoring days.

The MWEA24 product is a 24-hour Marine Weather Forecast. The above example was received at 0025UTC on 4th March 2019 on 12382kHz via JE1AHJ in Japan. The chart is split into two parts, sent in seascape orientation as a tall chart. It identifies clearly in the header as from XSG with the footer attributing the fax to National Meteorological Centre, CMA via Shanghai Coast Radio Station. The chart features a number of icons and fine text in the legends which could become difficult to read under weak signal conditions.

The MWEA48 product is the 48-hour version of the above, this example received at 0050UTC on 3rd March 2019 on 12382kHz via JH1PGF in Japan.

Likewise, the MWEA72 product is the 72-hour version, the above from 0115UTC on 3rd March 2019 on 12382kHz via JH1PGF.

This is the FXEA502 chart representing the 24-hour 500hPa gradients and Surface Forecast. The above example received 3rd March 2019 at 0255UTC on 12382kHz via JH1PGF. The chart follows a similar divided seascape layout, although the attribution is to the Shanghai Meteorological Bureau, CMA.

This chart is followed by the FXEA504 which is a 48-hour version of the above. This example was received 6th March 2019 at 0320UTC on 16559kHz via JH1PGF.

The final chart in the series is the FXEA507 which is the 72-hour version. This example received on 5th March 2019 at 0345UTC on 16559kHz via JH1PGF.

This is followed by the FWEA-series of charts which are wave height forecasts. The chart follows the same divided seascape format. In this period, propagation seems to swing wildly, resulting in deep fades, jittery faxes and some difficulty getting good reception (and the time on JH1PGF runs out). The above example is an FWEA24 chart, the 24-hour wave height forecast, received 4th March 2019 at 0410UTC on 12382kHz via JE1AHJ.

This is followed by FWEA48, the 48-hour version, received 4th March 2019 at 0435TC on 12382kHz via JE1AHJ.

The final chart in the series is FWEA72, which is the (you guessed it) 72-hour version, received 3rd March 2019 at 0500UTC on 16559kHz via AKKY in Japan.

The next series of charts are the FOEA charts which depict ocean current forecasts. The above is an FOEA24 chart which is a 24-hour ocean current forecast. The above is formatted identically as a divided seascape chart, but with very fine arrow details. The example above was received 5th March 2019 at 0525UTC on 12382kHz via JE1AHJ.

This is followed by the FOEA48 chart, a 48-hour version of the above – received 4th March 2019 at 0550UTC on 12382kHz via JE1AHJ.

The final chart in this series, the FOEA72 which is a 72-hour version (predictably), received 4th March 2019 at 0615UTC on 12382kHz via JE1AHJ.

While all charts up to this point (excepting the schedule) are rotated divided seascape charts, the following charts are short charts sent in the natural orientation. Again, the chart features some very fine detail, including a mention of the forecaster’s name in the header. The ASPN product is the surface analysis, received at 0730UTC on 4th March 2019 on 8302kHz via JH1PGF. This product is attributed to the National Meteorological Center, CMA – notice the differing spelling of centre/center compared to the MWEA products.

The FSPN24 is the 24-hour surface forecast, received 0755UTC on 4th March 2019 on 12382kHz via JH1PGF.

Finally, the FSPN48 is the 48-hour surface forecast, received 0820UTC on 4th March 2019 on 12382kHz via JH1PGF.

The only chart that was not received in the monitoring campaign is the tropical cyclone forecast. It appears that no transmission is made when no such cyclones exist in the forecast area.

Oddities

It seems that XSG may occasionally have issues – I have noted occasionally scheduled charts were not received but only noise was present. In one instance, I was able to receive a partial fax which cut down into the noise suddenly – I cannot confirm if this was an issue with the transmission or with the KiwiSDR receivers I used (as they could have been jammed by a strong transmission nearby or the antennas may have been suddenly damaged/disconnected).

Conclusion

The Shanghai Coast Radio Station (XSG) sends a regular schedule of fax transmissions with no repetition (excepting the tropical cyclone forecast chart which is only sent when a cyclone is within the area). The transmissions are heard within the area surrounding China, including Japan, South Korea, Hong Kong, India and Vietnam based on my observations, with a transmission power possibly similar to or slightly less than JMH. The best signals appear to be received in Japan given the state of KiwiSDR distribution at this stage.

The faxes themselves are quite unique – the phasing part of the charts consist of nearly 50/50 black and white which is not seen on any other transmission. Tuning tone (white) is observed prior to chart transmission and trailing tone (black) is also observed after chart transmission. WMO start/stop tones are also present, along with a black image margin. The station’s timing reference is practically perfect, with no slant correction required when using a GPS-referenced KiwiSDR receiver.

A mixture of short and (mainly) tall divided seascape charts are sent. Faxes contain unusually fine details interspersed with thicker lines, making it likely that poor signal conditions may result in some numbers being difficult to read.

I quite like the charts I’ve received from XSG as they are pretty unique because of the phasing alone. The transmissions are quite reliable, and reception through certain Japanese KiwiSDRs is very solid.

Thanks Vitor!

Radiofax Station Status [Updated: 7th March 2019]

The latest update to the slant factors are as follows:

Callsign	Correction
--------------- ----------
CBM/CBV		-90.0
DDH/DDK		-12.0
GYA		+34.0
HLL2		-18.0
HSW64		-11.0
NOJ/NMC/NMF/NMG	-4.0
KVM70 		-4.0
JFX		 0.0
JJC/9VF		+3.2
JMH		 0.0
RBW41		-17.0
VCO		-24.0
VMC/VMW         +18.0 (unwell)
XSG              0.0
ZKLF		+11.0
ZSJ             +100.0

The latest update to the station status are as follows – offline stations and stations reported inactive removed:

Station Status as at 7th March 2019 (based on my observations)
CALL  COUNTRY           STATUS
----  ----------------- --------------------------------------------
ZSJ   South Africa      * Alive but Unreliable (Published)
JMH   Japan             - Alive and Well (Published)
???   Chukota Peninsula ? Unknown, Not Heard
HLL2  South Korea       - Alive and Well (Published)
HSW64 Thailand          - Alive and Well (Published)
JJC   Japan             - Alive and Well (Published)
9VF   Singapore         - Alive and Well
PWZ33 Brazil            ? Unknown, Not Heard
CB?   Chile             - Alive and Well (Published)
VFF   Canada            ? Seasonal, Not Heard
VFR   Canada            ? Seasonal, Not Heard
VCO   Canada            - Alive and Well (Published)
VFA   Canada            ? Seasonal, Not Heard
NOJ   USA               - Alive and Well (Published)
NMC   USA               - Alive and Well (Published)
NMG   USA               - Alive and Well (Published)
NMF   USA               - Alive and Well (Published)
VM?   Australia         * Alive but (Temporarily) Unwell (Published)
ZKLF  New Zealand       - Alive and Well (Published)
KVM70 USA               - Alive and Well (Published)
SVJ4  Greece            - Alive and Well (Published)
RBW4? Russia            - Alive and Well (Published)
DD??  Germany           - Alive and Well (Published)
GYA   United Kingdom    - Alive and Well (Published)
JFX   Japan             - Alive and Well (Published)
XSG   China             - Alive and Well (This Post)

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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