Project: Scanning Sydney’s DAB+ & FM Broadcasts

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While on holiday in Hong Kong, I did some scanning of broadcast services over there and SydneyCityTV tipped me off that there were indeed slideshow services on DAB+ here in Sydney as well. It’s funny how we “get used to” the services around us and we don’t bother focusing on them, but now that I know, I might as well get cracking.

DAB+ Services

In order to do the reception of the slideshow service, I used the MagicRadio application with the MagicPro ProHDTV Mini 2. Unfortunately, I don’t have anything else that can receive the slideshow service at this time, and I did try RTL2832 tuners along with their supplied Blazevideo and PrestoPVR players with no luck. Even the SDR-J receiver doesn’t seem to decode the slideshow data.

Of course, things have changed somewhat since the last time I looked at DAB+, and the number and names of the channels has changed. Today, we have a total of 58 channels over three multiplexes, as this “composite” screenshot shows:

dabplus-scan

I went around all the stations, sitting on them for about three minutes to collect any representative slideshow graphics. To give it the best chance of success, I decided to use the roof aerial which gave me 100% signal quality over all multiplexes. I had no way of knowing whether there would be any slideshow however, and of many smaller stations, they don’t seem to send a graphic update for up to two minutes. I think that the slideshow data is implemented using excess bandwidth at a lower protection level, as despite having perfect audio on the ABC and SBS multiplex, the slideshow and text data was always garbled. This may be due to an encoding issue which is incompatible with Magic Radio.

A gallery still images taken from the slideshow feature is below:

Many of the stations share a similar slide-show layout if they are from the same parent broadcaster, and often share the same news and weather slides but themed with the colours and logo of the target station. Sky seems to broadcast quite a few slides on a regular basis, providing information to punters about horse races. Lots of promotions for mobile apps, station competitions and station programs are often sent, but they rotate only very infrequently compared to in Hong Kong.

The stations which did not provide any slide-show image after three minutes (possibly due to reception issues) are:

1  Fun Classic Hits
5  ZOO MusicVariety
7  Dance Anthems
8  Fine Music
10 GorillaDanceHits
13 2SM Talk & Sport
14 2RPH Digital
16 FairfaxRadio NTS
17 TheRange-Country
25 FBi Click
26 Coles Radio
27 Inspire Digital
31 2MFM Muslim DR
34 Pure Gold '90s
38 2GB 873
39 2CH 1170
43 ABC Country
45 702 ABC Sydney
46 ABCRadioNational
47 ABC Classic FM
51 SBS Radio 1
52 SBS Radio 2
53 SBS Chill
54 SBS PopAsia
55 SBS PopAraby
56 SBS PopDesi
57 SBS Radio 3
58 SBS Radio 4

Apna Digital was silent today (even on my standalone receivers), and for some reason, it always caused Magic Radio to crash. This might be something to do with incorrect station meta-data or a failure of their encoders.

FM Broadcast Band

I decided to do a scan of the FM band with an RTL2832U + R820T dongle using SDR-Radio v2 with rtl_tcp server. This was my preferred software due to its advanced RDS decoder and subcarrier visualizations. Unfortunately, it’s a little difficult to interpret at times because of the wide filter on the R820T meaning that you can receive faint “images” of stations which aren’t really on the air, so you have to be a little careful.

Received stations were logged as follows:

87.6Mhz Voice of Islam
87.8Mhz Radio Austral
88.1Mhz 2RDJ
88.5Mhz 2RRR
89.3Mhz 2GLF
89.7Mhz Eastside FM
90.1Mhz 2NBC
90.5Mhz Alive 90.5
91.3Mhz c913FM
92.1Mhz Mulsim Community Radio
92.9Mhz Classic
93.7Mhz Koori Radio
94.5Mhz FBi Radio
95.3Mhz smoothfm
96.9Mhz Nova 969
97.7Mhz SBSRadio
98.5Mhz 2OOO
98.9Mhz 98.9 FM for the Best Country
99.3Mhz Northside Radio
99.7Mhz 2SSR
99.9Mhz SWR FM
100.3Mhz 2MCR
100.5Mhz 2RPH
100.9Mhz 2BACR
101.7Mhz WSFM1017
102.5Mhz FineMus
103.2Mhz Hope1032
104.1Mhz 2DAY FM
104.9Mhz TRIPLE M
105.7Mhz triple j
106.5Mhz KIIS1065
107.3Mhz 2SER

Notably absent is “The Edge” 96.1Mhz which should be available in the Sydney area, which was probably due to the directionality of the reception antenna. I’m sure we’re missing quite a few others too. That being said, 90.9Mhz and 101.3Mhz was receivable (not shown below), and technically appear to be “out of region” reception.

There are many community stations, many of which do not send RDS information. Quite a few community stations seem to be having trouble – 98.5Mhz and 100.9Mhz was sending dead air! Most major broadcasters use RDS to send frequency information, time of day and radio text. It seems that 102.5Mhz Fine Music also sends a subcarrier audio service at 92khz (the only one observed to do so).

Conclusion

Thanks to a tip-off, I spent a good portion of the day tuning around the band just to collect slide-show images and RDS + Subcarrier graphs. Very few DAB+ receivers support the slideshow feature, and this is especially surprising given the RTL2832U dongles use software demodulation. It should be theoretically quite easy to implement it in software provided the specifications are known. Magic Radio with the HDTV Pro Mini 2 tuner probably follows the same software approach but with an RTL2836BU DTMB chipset instead.

The problems with receiving ABC and SBS slideshow and text seem to be unusual given the very solid 100% signal strength which makes me think it may just be related to an incompatible encoding or metadata description.

About lui_gough

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6 Responses to Project: Scanning Sydney’s DAB+ & FM Broadcasts

  1. Easton says:

    You should try an FM bandscan with a more sensitive radio – you’ll get a lot more stations. Usually car radios are quite good, I can easily get over 70 stations in Sydney with my car radio. Also, there’s no chance of 98.9 being “98.9 FM for the Best Country”, which is a Brisbane station. Most likely, it was Triple J from Knights Hill (Wollongong). The Edge is a pseudo-Sydney station as it is licensed to and broadcasts from the Blue Mountains, so it’s weaker than the other Sydney stations.

    • lui_gough says:

      Thanks for your correction and further information. I do have a Degen DE1103 which is extremely sensitive, but since it’s a portable radio, it wouldn’t have had any visible information on subcarriers or RDS like car radios would have. I don’t have any car radios around at this time, but I might try it if I ever have one. This post was mainly because of a want to survey the DAB+ Slideshows, with the FM being an afterthought.

      – Gough

  2. SydneyCityTV says:

    I know I’m a bit late to the party here, but quite an excellent post. 🙂

    As far as alternative DAB+ software goes, the “DAB Player” software seems to be pretty good for the RTL2832 tuners (although this page is in German – thankfully you can translate that and the software thankfully does have an English language option): http://ukwtv.de/cms/downloads-aside/281-dab-player-von-andreas-gsinn.html

    For the record, I’ve been using it for a couple of days (thanks to a recent post on the Media Spy forums, where users have given the software the thumbs up over other options) and I must say there’s plenty of features here including the option to easily display and save slideshow images (even on the ABC/SBS stations, which had trouble decoding on other, less stable DAB+ software) and being able to see more detailed info on station bitrates. Of course, you can also listen to DAB+/DAB radio stations and choose to record audio of them in MP3, WAV and MP4/MP2 formats.

    • lui_gough says:

      Now that sounds like the sort of software I’ve been wishing for for ages, but never had known about. Thanks for the tip – I will investigate thoroughly.

      – Gough

  3. Pingback: Melb2016: DAB+ Scanning & Slideshow Images (Part 10) | Gough's Tech Zone

  4. This is a great post. I’m working on a scanner for the LG Stylus DAB+ (that’s the little phone available in Optus stores), and might be fun to see if I can extract the slideshow.

    You might also look at RadioDNS, which is apparently supported for a few stations in Sydney, notably 2DAY. At least, the FQDN of 10410.2041.au.fm.radiodns.org returns something.

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