FM radio bandscan results – including London pirates

This post began life as a breakdown of an FM bandscan and dissolved into thoughts on RDS decoding and possible Raspberry Pi projects. I just wanted to jot down some semi-related thoughts.

Last weekend I popped up to Hampstead Heath to get onto high ground where I played with radios for a bit. One of those radios was my Moto G7 Power, using the built in FM Radio app, which is entirely decent (and I’ve written about using Moto G phones as FM radios before).

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When performing an auto scan of available stations, the app spits out a nice list of those stations, some with IDs. Unfortunately there’s no default way to convert this to text, but I found an OCR text grabber which did 95% of the work, and then I just monkeyed with a spreadsheet to sort out any oddities, and this is what I ended up with following an FM bandscan on 21/03/2020 at 1425 UTC:

MHz  RDS Station ID
87.8 | The Rock
88.0 | PULSE UK
88.2 |
88.6 |
88.8 | BBC R2
89.1 | BBC R2
89.6 |
90.2 |
90.6 | ANADOLU
90.8 |
91.0 | BBC R3
91.3 | BBC R3
91.5 | MEGA
91.8 |
92.0 |
92.5 |
92.8 |
93.0 |
93.2 | BBC R4
93.5 | BBC R4
93.8 |
94.9 | BBCLondn
95.5 |
95.8 | Capital
96.1 |
96.5 | [Maritime Radio] – no RDS data decoded
96.7 |
96.9 | Cap XTRA
97.1 |
97.3 | LBC
97.7 |
97.9 |
98.5 | Radio 1
98.8 | Radio 1
99.0 |
99.3 | SELECT
99.5 |
99.8 |
100.0 | KISS
100.6 | Classic
100.9 | Classic
101.2 |
101.4 |
101.8 | BiZiM FM
102.0 |
102.2 | Smooth
102.4 | LONDON’S
102.8 | RDYOUMUT
103.1 |
103.6 |
104.2 | -KRAL-
104.4 | Reel 104.4
104.9 | Radio X
105.4 | Magic
105.6 | PLAYBACK
105.8 | Absolute
106.2 | Heart
106.5 | PROJECT
106.8 | RINSE FM
107.3 | REPREZNT
107.8 | -JACKIE-

Where a station ID was decoded via RDS, it is listed. Where I’ve made it bold and italic, it is believed to be a pirate station. The rest are legit local/national FM broadcasts.

Where there’s no station ID listed, it’s simply because the FM radio app didn’t pick one up in time – some of those blank stations may a) be legit and b) indeed have an RDS stream, it just didn’t get logged in time. Either way, it could be pirate or legit.

A couple of them are stations that I knew had RDS data, and what’s nice about the Motorola FM Radio app is that if you tune to that station and it didn’t already have data, it adds it where possible, and this gets added to the overall list as above. This means that after a full scan, if there are gaps in the data, one can simply tune to the first station with a blank name, and let it play for a few seconds until RDS data comes down – if it has any. – and then use the skip button to move to the next logged station.

It only takes a few seconds for RDS data to appear, or for it to become clear that none is being broadcast. Weak signals inevitably mean the RDS data is corrupted, possibly beyond legibility.

Oona Räisänen could probably explain in quite simple terms exactly how RDS data is decoded and why some stations seem to display RDS data quicker than others. In fact, it’s Oona’s RDS projects that make me think that if I really set my mind to it, I’m probably like 90% of the way to creating a pocket-size, Raspberry Pi Zero-based RDS decoder.

What I think I want is a little device that I can pull out, attach to an antenna, run a quick 1-2 minute bandscan, and in that time, the Pi scans the whole FM band, logging as much RDS data as it can grab, plotting it neatly on a little spreadsheet, which I can then inspect later on.

Better yet might be adding a simple 2-line display (much like a portable radio) where I can see each station being scanned. There are other possible modifications that could be made that would effectively turn it into a usable radio, but I’m thinking more along the lines of a simple logging device.

On the other hand, it might make more sense to do some sort of spectrum grab using SDR where the whole FM band is captured for a few minutes, for later analysis in software. This whole concept blows my tiny mind – and, really, seems less fun than doing actual listening to live broadcasts – though I can absolutely see the appeal and the benefits for logging weak/rare stations when DXing.

2018 Weeknote 3

Another windy week, with the weather turning decidedly wintry as the days went by. We had strong winds – a repeat of the other week – and the Suburb actually had more trees brought down this time than last time. Curious, as I hadn’t noticed the wind at home. But the Suburb is often said to have its own micro-climate. And it does sit on the top of a hill.

Other than continuing office-based admin, I had a few meetings on-site, and some photos to take for a couple of upcoming meetings. I think I strike a good balance between being in the office and getting out and about. But I’m also mindful that there are whole bits of the area I’m less familiar with. I should set up some kind of patrol cycle.

Fortunately, the weather behaved itself on Friday night as M and I headed out to see the Lumiere festival of light. We went last time and loved it. This time there seems to be more to see, and although there were a few repeats – with installations on this scale, one can hardly blame them – we saw a number of great displays.

My favourite ‘genre’ is absolutely the intricate projections of light onto buildings, where the very edges and details of the architecture are ingeniously built in to the projected images. With music pulsing out of decent sound systems, the whole thing unfolds on a grand scale.

_mg_0029-1_mg_0053-1The other vast improvement on last time was the closure of a number of big roads, like Regent Street and Piccadilly.

It’s heartening to know that art – and art which is largely uncommercial, beyond just getting people out onto the streets on a winter’s evening – can be given such a priority. That said, my biggest disappointment was that the – admittedly impressive – new screens at Piccadilly Circus were left on, with the neighbouring Lumiere installation inevitably paling into insignificance next to it.

I glimpsed at the new tabloid Guardian, but this kind of evolution feels less important than it did in 2006, with the launch of the Berliner format, when I very much remember buying my first Guardian and arguably beginning an allegiance that exists in some ways to this day.

This time, the new format partly feels cheapened, and on initial sight recalls the design of the Evening Standard. I think it’s the double-row title. But I haven’t sat and read a newspaper in many months and am not in the position to start again. So the main outcome for me is a website/app redesign, and that feels like just another lick of paint, and rather less interesting.

This week in radio*, I found out that the Raspberry Pi can output an FM signal natively. I had been looking for projects to do with the Pi Zero I was kindly given by Troels when I visited him in Copenhagen, and hoped there’d be a radio-related one. So it was with some surprise that I realised I wouldn’t even need a transmitter module. So for the first time, this week I finally booted up the Pi and started tinkering with it. Oh god, it’s my first time playing with Linux in a very long while.

* this is definitely becoming a reasonable alternative title for these posts

Much to my good fortune, a friend was holding a sort of low-key hack day at his workplace on Saturday, with the intention for people to gather and just crack on with a personal project. I saw this as the ideal opportunity to mix with like-minded people and make some progress on a few things, including the Pi.

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It was a really positive day, with a good mix of folks I knew and some that I didn’t. All were friendly and helpful and laid-back. Everyone was working on A Thing, and there was some coding, some website design, some electronics and some admin and emailing going on.

I was kindly lent a keyboard and monitor which enabled me to make great progress on loading up the PiFM software. By the end of the session I had:

  • finished my FM receiver advent calendar kit – which has been incredibly fiddly but not unrewarding;
  • done another hour or so on the website I’m currently working on – it’s most of the way there, now;
  • set up the Pi Zero so that upon booting – with just power attached, and therefore a very small unit – it begins broadcasting a low power FM signal on a set frequency, playing a given folder of MP3 files at random.

Very satisfying.

On Sunday, met with slushy, not-quite-snowy weather, Megan and I went to the Tate Modern first thing so that she could do a recce ahead of leading a school trip. It was naturally a whistle-stop tour, but my first visit in many years.

The pendulum in the Turbine Hall was as delightful as I’d hoped, and it was good to see the new extension at close quarters. The view from the top was great, even/particularly on as misty and grizzly a day as today.

We whizzed around, trying to find prints and woodcuts etc, and trying to orchestrate routes with as few nudes as possible (provoking a philosophical debate over whether it was necessary to steer primary school children’s eyes or not).

Even despite this, I saw a couple of real highlights, the most impressive of which was Babel by Cildo Meireles – a floor to ceiling tower of radios, all lit up and playing audio.

Having not read the piece’s information panel, it took hearing the Archers theme song – bang on 11:15, it turned out – for me to realise that the whole point of the thing was that these were all real radios, all tuned to something real. How utterly fantastic. And what a cacophony. I loved it.

I was also heartened by the detail on an information panel for a video installation with words to the effect that the artist had first conceived the piece in 1965, with the version in front of me finally brought to fruition in 2002.

Encouraging words to reflect upon, if I ever feel like a project I’ve started will never get finished.

Sunday night we closed the week off with a visit from a dear friend of Megan’s, with the three of us scoffing a giant macaroni cheese in front of Aladdin.