The more I look at the world of radio in the traditional sense, the more it feels under threat. As a relatively late-comer to the shortwave and HF radio listening hobby and amateur radio, I’ve had the displeasure of seeing the closure of a number of services, relatively tough propagation conditions, increasing noise-floors in urban environments and increasingly antenna-hostile communities. More than that, I also see a dwindling number of hobbyists interested in the field, with some of the elderly making an involuntary exit as their health overtakes their interest.

In this environment, I felt it was a good idea to make some effort to preserve some of what makes shortwave and HF interesting. This included articles about DRM broadcasting, WebSDR/KiwiSDR receivers and collections of signals such as WeatherFax, VOLMET and NAVTEX. When I looked down the list of services I haven’t looked at preserving, the one that stood out to me was HF Weather Voice services.

HF Weather Voice

For mariners at sea, HF weather voice services provide critical weather information without the requirement or expense of satellite equipment. This often entails long broadcasts with weather forecasts being read out over the air periodically, by human or by machine and sometimes in more than one language, along with the characteristic noise and fading that often accompanies HF SSB transmissions. This service is an alternative and often complements the weather fax which provides graphical information and NAVTEX which provides textual information. The main advantage to weather fax and NAVTEX is that unattended reception is possible and routinely used whereas voice is often used in attended operation only (although recordings are possible).

Luckily for those who are interested in HF Weather Voice services, there is a long (although possibly unmaintained) list of service frequencies and times listed on this HFUnderground page. Unlike shortwave broadcasts which often change frequencies on a seasonal basis, most utility services maintain their frequencies consistently for many years to avoid inconvenience. As a result, while the listing could be somewhat dated with some of the transmitting stations no longer on the air or no longer transmitting at a given time-slot, it should still be reasonably accurate with regards to frequencies.

The Preservation Effort

I started my efforts with the data from the HFUnderground Marine Weather Transmissions page. Extracting the list of transmissions, I sorted them by country, aiming to receive a transmission from as many as I could. From the list of available frequencies for each country, I selected a frequency (or two) which would be most likely to be received (i.e. more transmissions, in a band good for propagation around the clock).

Reception was performed using KiwiSDR receivers which are publicly available on the sdr.hu website, using the kiwirecorder.py program. Audio settings were set for uncompressed audio, USB demodulation with a 20Hz to 3000Hz passband. Recordings were taken at the KiwiSDR receiver most proximal to the expected transmission site, although alternative receivers were used in case of strict time limits or poor antenna performance. Recordings of the most promising frequency were made for a period of between 12 to 24 hours on my VPS server (as my home internet is unstable), segmented by hour and losslessly compressed for transfer to my desktop.

Once the compressed files are collected on my desktop, I used an audio editor with spectrogram view to identify periods of voice transmissions (if any). Recordings of the best voice transmissions (in terms of signal-to-noise ratio) from each country were extracted from the recordings, resampled to 8000Hz and then exported as an AAC-HE audio file. FFmpeg was also used to generate an accompanying spectrogram image.

Should nothing be heard, another attempt would be made for a given country by choosing the next most promising frequency. Otherwise, a second receiver would be chosen to attempt reception. Multiple KiwiSDR receivers would be engaged in parallel within the October to November period for this first attempt, although I would not open more than one stream to any given receiver to avoid denying service to other users. However, in some cases, it was difficult to receive anything due to the low frequencies used by some stations, a lack of nearby receivers, limited transmission coverage area, presence of interfering signals, unreliable connectivity on the receivers or possibly due to service discontinuation or difficulties. Because of the extensive number of frequencies and countries, monitoring efforts took quite a lot of time over a period of two months, with processing taking some time over another month.

Having never heard the HF weather voice services of stations other than just my local neighbours (i.e. Australia, New Zealand, Thailand and USA), this project gave me the opportunity to listen further abroad and experience just how the other services sound like. However, because of the methodology and positioning of the available receivers, the quality of the reception may not be ideal in all cases.

The Recordings

The following section contains the gallery of successful reception recordings sorted into sub-headings for each country, sorted alphabetically. The information within the recordings is only accurate for the date and time it was received and is not kept up to date and should not be used for navigational purposes. Copyright in the transmitted information is believed to belong to the transmitting agency, however, the recordings are made by myself utilising the publicly available KiwiSDR receivers. They are provided here for documentary purposes, to illustrate the nature of HF marine weather voice transmissions from various countries at the listed dates and times.

Click on the spectrogram image or the link underneath to hear the audio.

Australia

Transmissions from Australia come from two transmitters – VMC (East) and VMW (West) with the information conveyed by a recognisable synthesized male voice.

This recording was received 20191101T2023Z_8176kHz and is an informational broadcast informing listeners of the weather voice frequencies in use.

This recording was received 20191101T2030Z_8176kHz and provides the forecasts, warnings and coastal observations.

Belgium

Transmissions from Belgium were received from Ostend Radio, transmitted by a real person. Transmissions are preceded by a tone and the securite call to all ships.

This recording was received 20191108T1426Z_2761kHz with new maritime safety information 673.

This recording was received 20191108T1433Z_2761kHz with repetition of maritime safety information.

This recording was received 20191108T1435Z_2761kHz with new maritime safety information 673, read by another operator.

Canada

Transmissions from Canada appear to use voice synthesis and are frequently made in both English and French. Transmissions are prefixe