[Talk-GB] link microwave masts

[Dan Glover]

On 2021-01-01 11:31, Robert Hanwell wrote:

> I think it's worth doing as reference. Data can be pulled out later
> for other projects?

I'll send Robert an extract from my data separately.

Looking at the Ofcom site, the relevant dataset is the "Wireless 
Telegraphy Register" - "Ofcom provides this information under Section 31 
of the Wireless Telegraphy Act 2006" - I haven't checked whether the WTA 
imposes any restrictions on the use of the data, suspect S.31 is just a 
requirement for the data to be made available.  More generally, Ofcom 
data is under the Open Government Licence, unless otherwise specified, 
and I don't see anything which indicates the WTR data has terms other 
than OGL https://www.ofcom.org.uk/research-and-data/data/opendata

So I suppose the first hurdle is determining whether the WTR data can be 
used to add things to the map - and then whether it is useful in terms 
of content and accuracy.

As a worked example, there is a site near here (built by BT in the 
1980s) known as Rough Common. The WTR data has six entries for British 
Telecom with the relevant NGR, expressed as TR 12470 59750 (which is 
"accurate" until we consider offsets and whether the exact position of 
the tower is perhaps more relevant, or the building, rather than just a 
point which falls within the site boundary. The site is currently mapped 
as a Communication Tower and tagged operator:O2 amongst other things - 
https://www.openstreetmap.org/node/1353989564

The WTR data lists the microwave link transmit and receive frequencies 
separately, so the six entries relate to three point-to-point links. 
Looking at the French map 
https://carte-fh.lafibre.info//index.php?zone=uk as a shortcut, however, 
there should be several more operated by BT (as well as other operators, 
which I've excluded from this analysis). As that map is based on Ofcom 
WTR data one of us has taken a wrong turn. No matter, this is just a 
thought experiment. From past correspondence with the creator of the 
French map I understand he found a way to identify the remote ends of 
each link from the WTR data - there will be a matching pair of 
transmit/receive entries. A past examination of the local links showed 
they were to a mixture of BT and other premises, sometimes mobile phone 
sites.

However there are no operational links between the old trunk sites (the 
antennas were removed several years ago) just clusters of local links 
using the towers. The 1980s technology had high running costs and fibre 
has overtaken what was possible on microwave links so there was no 
longer any operational advantage.

It might be possible to grind through the Ofcom data and produce a 
distinct set of sites used for microwave links but I suspect this 
process would be more trouble than it's worth - probably can't be used 
to create nodes automatically since there are definitely errors within 
the dataset and many of the locations will turn out to be buildings not 
communication towers.


Dan