naxxfish

(featured image is a Class 800 test train set spotted at Paddington shortly before the launch of the Intercity 125 replacements in October 2017, operated by GWR and Virgin East Coast)

As a long time user of Realtimetrains.co.uk , and someone with an appreciation of Open Rail Data (having used it myself), I jumped at the chance of helping their development.  They’ve put out an appeal to record GPS tracks of train services that you travel on with the link to the service on the application.

A lot of the work behind the scenes performed by a small team involves maintaining data relating to train positioning and comparing this with the signalling system outputs we use. This is an entirely manual task involving one of us going out with a radio controlled watch and monitoring the passage of trains through stations and junctions. An area of recent interest for us has been attempting to compute this automatically using other known bits of information.

In order to validate this effort, we either have to do the manual task with a watch or collect a large dataset of GPS traces to compare against our dataset. The more data we have will allow us to improve the end product.

Which is awesome.  I wanted to contribute. I found a suitable app for Android called GPSlogger which seemed to fit the bill.  It has quite a few settings, so I thought I’d write a quick guide on what I’ve used to successfully generate a working track for a service.

Wanting to make sure the data I produced was as useful and error free as possible, I asked @Realtimetrains for some guidance

It does two checks, relating to distances between points. First is that the median distance between point in your file is less than 250m apart, second is that the 90% percentile point is less than 250m. Some of the stuff we're checking against them requires a fair whack of points

— Realtime Trains (@realtimetrains) March 14, 2018

When we've been taking the logs we've been going for as frequently as we can. The main thing we need is temporal data (or we'd use OSM, etc!) as this is where our interest is focusing, obviously the more points the better. We're trying to avoid recommending any particular app 1/2

— Realtime Trains (@realtimetrains) March 14, 2018

I have put together some settings that should help achieve these goals using GPSlogger.

Continue reading “🗺️ Recording GPS Tracks with GPSlogger on Android for Realtime Trains 🚆”

One of the unique challenges of CSR FM is it’s structure, where it is part funded by two separate universities each with a presence in Canterbury (University of Kent and Christ Church University) and their respective student unions (Kent Union and CCCU).  Student members could be enrolled at either institution, and as such each institution has it’s own radio studio on campus – each of which has an equal chance of being put on air. The station also invites members of the community to participate. 

This has presented a challenge, in that live audio needs to make it’s way from either studio to the transmitter, hosted at the University of  Kent in Eliot College.  From the outset of the CSR project, the route between the two has always been over IP – there was no other reasonable option.  Up until recently, that was realised using a IP Codec – with it’s packets being routed over the institution’s networks.

This is perfectly fine, and for the most part worked very well.  However, recently CSR has had a fundamental infrastructure change to it’s audio distribution (as part of the Student Media Center project), which has made every single audio source and destination available using Axia’s Livewire Audio over IP protocol over their internal network.  This allows fantastic flexibility and allowing studios to route any source to their mixing consoles, as well as increased interoperability with our automation systems and customisable GPIO control.

However, the second studio (Studio Blue) was still connected via an IP codec link, which was not integrated into the system at all and offered limited capacity for routing over the link (only a stereo pair to and from the router).  Unfortunately the link between the two sites, over the academic networks that link the universities, would not be suitable to transport Livewire (for a number of very good reasons, lack of multicast and custom QoS being one).  It was therefore necessary that we provided a Layer 2 link between the two locations to carry this traffic, which we had complete control over.

Continue reading “CanterburyMedia Site to Site Link”