29 MHz

Introduction

The 2022 RSGB band plan http://rsgb.org/main/files/2022/02/220126_2022-Band-Plans_RadCom-web.pdf identifies 29000 - 29510 kHz segment as available for experimental wide bandwidth operation on a non-interference basis to other stations, including the amateur satellite service segment at 29300 - 29510 kHz. In practice, this means we can experiment with reduced bandwidth DATV on 10m. The 10m band opens for worldwide DX around solar maximum, so theoretically and now in practice it is possible to transmit video worldwide.

These pages are intended cover the experiments, noting they are experiments, that may require significant effort in construction of equipment, development of software and quite a but patience in order to participate. So far, signals have been sent across the Atlantic by several amateurs using very low symbol rates. There is much still to do to improve performance and reliability. If that interests you, you are in the right place.

Equipment for 29MHz DATV

Generally, we can generate DATV signals in the same way we do for higher frequencies.

The popular software defined radios that are used to transmit DATV at higher frequencies are the Adlam-pluto and Lime Mini. The pluto does not work below 70MHz and while the Lime Mini does cover 29MHz natively, in practice the spectrum it generates in this region is not sufficiently clean to use on the air. Consequently, to use either device for transmitting it is best to down-convert from a higher frequency, for example with a 2m to 10m transmit downconverter.

Similarly on receive, the popular minitiouner used at higher frequencies does not tune down to 29 MHz. An upconverter is needed to translate the signal to an IF within the range of the tuner. A better option may be to use an HF SDR and decode the signal in a software package like GnuRadio or SDRAngel.

Software for 29MHz DATV

ffmpeg - for generating the encoded video stream SDRAngel - for receiving

Generating a low rate transport stream

There isn't much bandwidth available on 10m which means relatively low symbol rates are needed, probably occupying no more than 100kHz of bandwidth, ideally less.