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.
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:
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).
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.