Radiofax: HLL2 Seoul, South Korea (Korean Meteorological Administration)

When it comes to radiofax, you might be wondering why I’ve left South Korea’s HLL2 station towards the end. The reason? It’s actually not an easy station to receive well. As many utility stations are established on a frequency and only change under extreme circumstances, HLL2’s set of five frequencies, four of which are active at any time, proved to be quite problematic. Amongst the frequencies, two of them were often interfered with by AM broadcasters, and others by morse transmissions or QRM from what appears to be over-the-horizon-radar or ionospheric sounder equipment. The remainder of the frequencies generally propagated poorly, resulting in a lot of frustration. While I have received them from home in the past, the signals were almost always quite weak.

This time, I attacked the problem from multiple directions. As part of my trip around Japan in 2017, I bought a mobile kit of HF reception equipment consisting of my BladeRF with transverter and the Sony AN-LP1 to attempt reception of fax stations closer to the footprint which did yield limited results.

Similarly to a number of radiofax postings I have made recently, I have made use of a number of KiwiSDR receivers to obtain more results worthy of presentation. Specifically, the aim was to maximise the quality of the received images, which led to my utilisation of a lot of receivers including JP7FSO, AKKY, JF0FUM, Soy Sauce in Chiba, HL5NTR and the KiwiSDR at the Northeast Asian Broadcasting Institute. Unfortunately for me, the two South Korean SDRs available both showed fairly poor reliability with one falling offline frequently and the other having a restrictive daily-time-limit. Regardless, with some persistence, some results were achieved.

The charts presented represent a snapshot in time and are not kept up to date. They are not to be used for navigation. Copyright in the faxed materials belongs to the issuing agency, the Korean Meteorological Administration of South Korea. Faxes are reproduced for documentary purposes including an examination of the technical aspects of transmission, formatting of data within the charts and as proof of the activity status of the station, the signal propagation behaviour and reception on the dates and times noted in the posting.

Faxes

I’ve tried to group the faxes by type as it seems to be a better way to present them.

System-related charts

We begin with what is arguably the most important fax transmission, the broadcast schedule. This schedule is dated on the date of receipt as 1st February 2019, received at 0000UTC on 9165kHz and is in Korean (unfortunately). As it is sent sideways as a short chart, the resolution is a little too limited for automatic translation. However, its reception is sufficient to cast doubt on the schedule published by NWS/NOAA which appears to be inconsistent with this.

At 1140UTC on 31st January 2019, what appears to be a service notice is received on 3585kHz in Korean which states the contact details in regards to the provided service. Note the reception including the slightly long start tone, slightly short phasing and stop tones and black margins in the image area. This seems somewhat consistent with the Japanese fax stations to some extent.

A symbols and test chart is sent with a Korean legend for the iconography used in the charts. The above noisy but sharp example was received 1140UTC on 13570kHz on 31st January 2019.

A slightly fuzzy doppler-affected version was received 1147UTC on 1st February 2019 on 3585kHz.

Occasionally, some charts are not sent, resulting in a “no data” short fax as above.

Typhoon alert charts appear to be sent sideways, the above being related to typhoon Pabuk, received 1804 AEDT on 2nd January 2019. Unlike the majority of weather charts, the shaded projected typhoon path makes use of the greyscale capabilities of radiofax transmission.

Satellite Imagery

HLL2 was among the few stations which sent satellite images via fax using greyscale capabilities, but offering superb contrast and detail in the images. This rather “square” aspect image was received during my holiday from Japan, at around 1943 JST on 23rd September 2017. Note this older transmission has white image margins.

While satellite imagery is still sent, it seems the aspect of the chart has been changed and it is now shorter in length with black margins instead. This example received 1st February 2019 at 0430UTC.

AS?? charts

The surface pressure analysis charts are coded as “ASAS”, which there are two charts. This chart featuring the DFS logo in the bottom left is a “short” chart with ASAS HLL written clearly in the legend. The above was received 0400UTC on 1st February 2019 on 9165kHz.

An even shorter version with some grey/thinner lines is marked ASAS KMA, also with DFS in the lower left corner. This example received 0026UTC.

There is another surface pressure product which is coded ASFE following similar conventions as ASAS HLL but with the date written at the lower right corner and upper left corner as well. This example received 0147UTC.

A forecast pressure chart in the even-shorter form with greyscale is broadcast as FXAS24 KMA. This example received 2nd February 2019 at 0248UTC.

Wind speed, direction and wave heights are provided in the FWAS product, a 48-hour forecast shown received at 0233UTC.

?UAS50 charts

The AUAS50 represents the height (GPM) and temperature (C) analysis, this chart featuring a DFS logo in the bottom left which seems characteristic of some charts from HLL2.

The FUAS50 chart is the 500kPa Forecast chart for height (GPM) and temperature (C). Confusingly HLL2 broadcasts two FUAS50 charts, one for 24-hour (received 0214UTC on 1st February 2019 on 9165kHz) as above.

There is also a 48-hour version which is only differentiated by the caption, this received 0530UTC.

FWK-series charts

The FWK-series of charts appear to be forecasts of wave and wind directions. The series comprises of six short charts all with the same rotated-image format. This FWK01 chart was received 0700UTC on 1st February 2019 on 9165kHz.

That was followed at 0714UTC by the FWK02 chart.

And again, at 0728UTC by the FWK03 chart.

This FWK04 chart was received on 2nd February 2019 at 0100UTC.

This FWK05 chart was received 1st February 2019 at 0114UTC.

Subsequently, that was followed at 0128UTC by the FWK06 chart.

FSST-series charts

The FSST-series of charts describe the surface temperature. Note all charts are short charts and share the header including Glosea5. This example of FSST01 was received 2043UTC on 1st February 2019 on 3585kHz.

This example of FSST02 is received at 1855JST on 23rd September 2017 while in Japan on holidays.

This example of FSST03 was received 2130UTC on the same day and frequency as the FSST01 chart above.

FSI-series charts

The FSI-series charts appear to be related to sea ice. Note the GloSea5 indication in the top-right corner which may be the name of their model. The above chart is an FSI00 chart received 1047UTC on 1st February 2019 on 3585kHz. All charts are of the “short” type.

The above is an example of FSI01 which was received 1115UTC.

Finally, an example of FSI02 received 1125UTC on 31st January 2019 on 13570kHz. It appears increasing number indicates number of days the product is forecasting.

Other Charts

A few other charts that don’t fit in the broad categories above are shown here.

One of them is the Global Sea Surface Forecast which shows wind speed, direction and wave height on a 72-hour forecast. It looks like it should have been coded as an FWAS product, but it instead does not carry any alphanumeric designation. The example above was received at 0310UTC on 1st February 2019 on 9165kHz.

The same observation regarding lack of letter-code designation also applies to the daily sea surface temperature chart, the above received 1st February 2019 at 0340UTC on 9165kHz.

Finally, the wave analysis chart coded AWKO, received 0414UTC, also doesn’t quite fit into the categories above. The font used in the legend area is slightly different on this as well.

Conclusion

It seems that HLL2 offers a number of differently formatted charts with a particularly pleasing variety of formats. It has some similarities in product naming with the Japanese JMH station as well, however, the formats are much less consistent by comparison. The station appears to have had a change between 2017 and 2019 with the image margins changing from white to black and the satellite imagery becoming shortened, and there appears to be no English schedule available (although I have attempted to contact KMA for assistance) with the NWS/NOAA guide appearing to be out of date. The frequencies that HLL2 operate on are frequently interfered with and make clean reception difficult requiring some careful planning and extensive monitoring to be able to collect the charts shown above.

Source: MakerFeed.net

Leave a Comment