There are basically two kinds of 4G masts:
Frequency | Range | Bandwidth
----------|-------------|----------------------------------
800MHz | Long (500m) | Low (can handle a bit of traffic)
1800Mhz | Short (5km) | High (can handle lots of traffic)
The 1800Mhz masts are better in terms of how much traffic they can
handle and how fast a connection they provide. But because they have
quite short range, it’s only economical to install them in very built up
areas†.
In more rural areas the 800MHz masts are better because they cover a
wider area, and have enough bandwidth for the lower population density.
The net effect of this is that cell broadcasts in rural areas are likely
to bleed further, because the masts they are being broadcast from are
less precise.
We can use population density as a proxy for how likely it is to be
covered by 1800Mhz masts, and therefore how much bleed we should expect.
So this commit varies the amount of bleed shown based on the population
density.
I came up with the formula based on 3 fixed points:
- The most remote areas (for example the Scottish Highlands) should have
the highest average bleed, estimated at 5km
- An town, like Crewe, should have about the same bleed as we were
estimating before (1.5km) – Pete D thinks this is about right based on
his knowledge of the area around his office in Crewe
- The most built up areas, like London boroughs, could have as little as
500m of bleed
Based on these three figures I came up with the following formula, which
roughly gives the right bleed distance (`b`) for each of their population
densities (`d`):
```
b = 5900 - (log10(d) × 1_250)
```
Plotted on a curve it looks like this:
This is based on averages – remember that the UI shows where is _likely_
to receive the alert, based on bleed, not where it’s _possible_ to
receive the alert.
Here’s what it looks like on the map:
---
†There are some additional subtleties which make this not strictly true:
- The 800Mhz masts are also used in built up areas to fill in the gaps
between the areas covered by the 1800Mhz masts
- Switching between masts is inefficient, so if you’re moving fast
through a built up area (for example on a train) your phone will only
use the 800MHz masts so that you have to handoff from one mast to
another less often
The `/accounts` page was listing trial mode services twice if a user
belonged to an org. They were shown under both the 'Live services' and
'Trial mode services' sections. After this change, 'Live services' will
show all live services (whether or not they belong to an org) and 'Trial
mode services' will show all trial mode services. If a user belongs to an
org, they will also see the summary of how many services per org at the
top of the page.
A couple of services in tests were renamed for clarity.
We used to upload this to performance platform to show the list of
services and organisations.
There is no longer a performance platform to upload this file to.
This uses the existing endpoint so it matches what’s on the homepage.
It will be more up-to-date than the list of services, but no-one’s going
to be adding things up to check they match exactly.
This matches the existing performance platform page, and I think is a
bit easier to read for high-level numbers where you don’t need to see
that they’re changing second-by-second.
Sometimes we get a service ID from a support ticket or a Slack
discussion. Rather than having to hack the URL, this PR augments the
‘Find services by name’ page to support service IDs. If a UUID is
entered, it assumes that it’s been given a service ID, and redirects
straight to the dashboard for that service, without showing any search
results (a complete UUID would never match multiple services). If the
UUID is not a service ID, the user will get a 404.
The links in the blue boxes on the job page needed hidden text so that
they work out of context. This changes the text from "10 sending" to "10
sending text messages" (with the message type hidden text).
All services have the `upload_document` permission now, so we don't need
to check for it on the email formatting page. This also deletes a test
which is not needed now.
Note, no option at the moment to set the service broadcast account type
as None, or back to without the broadcast permission. This has been done
for speed of development given the chance of us needing this is very
low. We can add it later if we need to.
* We don't need the inset text to be inside `<div>` tags because the
component adds its own
* Replaced `bottom-gutter` with `govuk-!-margin-bottom-6` since this
change will be needed across the app at some point.
This adds spacing classes from the design system where necessary to keep
the spacing looking the same.
It also replaces the `<aside>` elements with a `<div>` on the edit
template pages. The accessibility audit noted that these were inside a
`<main>` element, so screen readers may not be able to navigate the
elements correctly.
