Radiofax: CBV/CBM (Armada De Chile, Servicio Meteorologico)

Onto another radiofax station I have never heard before. CBV and CBM are a pair of stations in Chile. They operate two separate schedules but seemingly broadcast the same sorts of charts covering the same areas, but at different times. Due to their location and claimed 1kW output power, I have never been able to hear the station from home.

With the advent of KiwiSDRs, remote radio operation provides an opportunity to attempt reception and verify the activity of the station. Rather unfortunately, South America still remains relatively sparse in terms of publicly available KiwiSDRs. As a result, it was extremely difficult to get any copy on these stations whatsoever.

In the end, only two KiwiSDRs were able to get any level of copy – LU5AGQ in Argentina and Paraguay SDR. Because both SDRs were not quite reliable (going offline frequently or suffering breaks in reception), receiving the CBV/CBM charts were quite frustrating. Adding to this, it seems that CBV and CBM both sometimes have scheduling issues resulting in late starts. At least I do have a few charts to show to prove the service is still running.

Note that these charts represent a snapshot of reception at one point in time and are not updated. Charts should not be used for navigation purposes. Copyright in the chart data remains that of the transmitting agency, Armada De Chile, Servicio Meterologico. Charts are reproduced for documentary purposes to show the type of charts transmitted, transmission characteristics and proof of activity/propagation reception.

Faxes

Surprisingly, my first attempt at reception on 14th January 2019 at 1100UTC on 8677kHz via LU5AGQ proved to be the best amongst the several days I spent monitoring the station. Starting late and fumbling over the Fldigi slant options resulted in some “damage” to the chart. But it is readable, along with a correction to the schedule. Interestingly, transmissions are not made in English – most other radiofax stations are.

The chart that follows is a surface analysis. The chart has a relatively short start tone and phasing sequence. This is followed by a gradient bar from white to black, with text on the left side of #0001. This bears resemblance to SVJ4 and HSW64’s faxes – I suspect very similar equipment is used to encode them. This fax is sent in portrait with some rather bold lines and a scale at the bottom left.

This is followed by a satellite image in greyscale, a short fax.

At other times, it is possible to receive a wind barb isotach forecast chart (2230UTC), as above, received 18th January 2019.

This was followed by the 48h surface prognosis (2310UTC), received on the same day.

The only reception of CBM I managed was on 8696kHz at 2319UTC on 16th January 2019. The above chart was received via Paraguay with no slant correction and resulted in a very “dirty” fax but at least the header text is legible. The fact the frequency is active shows that the station is still active.

Conclusion

While I had to go the “extra mile” in opening every South American receiver to try and receive the signal (at one stage), the results seem a little disappointing with noisy charts all around. However, the reward is the proof that both CBV and CBM are operating, a good partial-schedule copy and the realisation that the charts have similarities to SVJ4 and HSW64’s charts in scale-bar and header text. Maybe this would be a target to revisit in the future.

Update #1

Instead of starting a whole new post, I decided to just update this one with new receptions made on 9th February 2019 via LU5AGQ’s KiwiSDR. While the SDR is taken offline quite frequently, I was able to get slightly better interrupted copy this time around. I was also informed that the charts are available online at: http://web.directemar.cl/met/jturno/indice/english.htm

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