It’s been a while since the trip, but I’ve been just way too busy lately to post anything more about the experiments and photos I’ve taken during my trip. The trip continues, with this part focusing mostly on more radio related goodness from the comfort of the hotel room and some night shots from nearby.
In an earlier part, I did make a full analysis of the on-air DMB-T transmissions offered in Hong Kong, using a small thin stick-aerial. The analysis was done based on captured TS files, although I did actually start with the included Arcsoft software. The Arcsoft software did allow for display of Chinese characters, so the Chinese channel names and LCNs were shown instead of the English ones in the SDT.
So lets look at something I didn’t look at in the previous parts – digital radio. One of the best things about having the local-TV-tuner dongle is that it also supports receiving DAB+ via the Magic Radio application.
In Hong Kong, digital radio is done by DAB+ in the VHF band, almost identically to Australia. There were a total of 17 DAB+ stations available when I was there, as shown by the scan results:
It seems there are only limited numbers of digital radio operators – mainly URadio, Digital Broadcasting Corporation (DBC), Radio and Television Hong Kong (RTHK) and Metro Broadcast Corporation (M). Interesting, all the stations were broadcast from one multiplex, whereas in Sydney, we have three. The multipath selective fading was clearly shown when looking at the carrier in SDR# from my RTL-SDR, making a very interesting “arty” pattern. The dips in the signal are quite significant – often 20dB down, so the error correction did a great job of keeping everything “listenable”.
I’ve never had any DAB+ receiver which was capable of more than just audio reception and basic text display, but in Hong Kong, it seems that many of the DAB stations also use the slideshow feature and broadcast still images of station logos, and news-headline images. This uses the spare bandwidth capacity of the DAB+ carrier to carry the images. Sometimes they do come out corrupted, but I doubt many of the DAB+ receivers will make such images available to the end users.
Some station logos caught include:
Interestingly, it seemed that RTHK also suffered a broadcast failure, so they broadcasted an apology in their slideshow as well, which I managed to catch.
AM and FM Broadcast
As you can tell from above, I did bring along my RTL-SDR dongles to get a bit of a view of the radio spectrum. But that wasn’t all. I carried along a conventional Degen DE1103 AM/FM/SW radio as well, just to make sure I could access the lower bands should the need arise. The Degen DE1103 is a fantastic receiver for the size and for the price, with the most sensitive WFM and SW performance I have seen in a compact. It comes with a stupid keypad, and a needless LCD, but has a excellently long telescopic antenna, a BFO for SSB reception and external antenna jack. The best part is that, with a keyboard hack, you can also get LW reception as well.
The first thing I did was to try and scan around the AM band for some transmissions. My expectation was not to find any, because it’s a fairly old transmission method. To my surprise, there were a few. The listing below is in khz, and may be off by 1-2khz.
569, 620, 676, 748, 785, 864, 1061, 1215, 1289
The FM band, however, is the big surprise. The FM band was crowded beyond belief. On a sensitive radio like the DE1103, the band is frustrating because of the sheer number of stations received, in Mhz. The values might be off by 0.1-0.2Mhz because of the FM capture effect.
87.4, 87.5, 87.7, 88.1, 88.3, 88.5, 88.9, 89.2, 89.5, 89.8, 90.1, 90.3, 90.7, 90.9, 91.1, 91.4, 91.8, 92.1, 92.5, 92.9, 93.3, 93.9, 94.2, 94.4, 94.8, 95.2, 95.6, 95.8, 96.0, 96.3, 96.9, 97.1, 97.5, 97.9, 98.1, 98.4, 98.7, 98.9, 99.1, 99.3, 99.7, 100.2, 100.5, 100.8 100.9, 101.1, 101.4, 101.5, 101.8, 102.0, 102.4, 102.5, 104.0, 104.3, 104.5, 104.9, 105.2, 105.5, 105.7, 106.2, 107.0, 107.5, 107.7
The scan results, represented on a number line, with dots spaced 200khz, 250khz and 300khz illustrates just how closely spaced the stations are.
A scan using Magic Radio shows only the strongest stations due to the lower sensitivity.
Overall, the FM broadcast band in Hong Kong is just way too crowded. This doesn’t help because of its proximity to Shenzhen, China, which is probably broadcasting its own FM stations to its own band plan, spilling over into Hong Kong. The audio quality in general is very distorted on many stations, with stereo lock being lost frequently on loud portions, and adjacent channels sometimes being captured.
Part of the reason is due to the challenging terrain, which results in the need to put in many repeater stations to fill-in. These repeaters operate on a separate frequency, using up precious spectrum. As a result, tuning across the band, it is possible to find six copies of the same program simulcast, each with different levels of interference and signal strength.
Interestingly, there are quite a few English-based services on the air, and it was possible to hear a lot of songs you would hear on Aussie radio. I felt “at home” in a sense.
It seems the quality of service is quite poor even for stationary listening, unlike in Sydney, where the signals are less crowded and generally “clean”.
A check of the spectrum using the RTL-SDR did turn up some very unusual spectrum behaviour – selective frequency fading which may be a result of co-channel broadcasting, multipath or something else entirely. There are also cases of spattering across on adjacent channels, non-symmetrical signals.
Decoding RDS from the transmissions was very much a mixed bag due to the unusual FM carrier characteristics noted in the above shots.
I did try for shortwave services, but the mass of local QRM from switching power converters, energy saving lamps etc swamped out any hope of being able to receive it with anything short of a shielded loop antenna, so I gave up.
Other Radio Transmissions
Of course, there’s a lot more to radio than just broadcast. I didn’t have that much time, but I did a rough scouring of the bands and came up with a very rough (and uncertain) band-plan:
69 - 80Mhz - NFM Voice 87.8 - 108Mhz - WFM Broadcast 108 - 136Mhz - Aviation Band 136 - 156Mhz - NFM Voice 156 - 162Mhz - Marine Band 162 - 172Mhz - >?< 172 - 173Mhz - POCSAG Pagers 173 - 279Mhz - Analog TV >?< 279 - 280Mhz - POCSAG Pagers 280 - 396Mhz - Analog TV >?< 396 - 430Mhz - Digital Voice (TETRA) 430 - 852Mhz - Digital TV >?< 852 - ???Mhz - Digital Voice (TETRA, GSM)
Interesting points include the use of the below-FM broadcast band for narrowband FM voice services, which is not that commonly used here in Australia anymore. The long antennas and limited transceiver choices are just some of the reasons why it’s not common to see it anymore.
I did manage to catch two ATIS services, one for arrival, and one general and the Hong Kong ATIS shares an unusual characteristic of dropping the carrier in-between loops.
POCSAG pagers are still on the air, which is pretty interesting too given the antique-status of the technology topping out at 2400bps.
The 400Mhz band has already moved over entirely to digital voice technology, utilizing TETRA standard which is encrypted. We are only just in the throes of moving over to more spectrally-efficient transmission modes, such as APCO P25, DMR/NXDN, MotoTRBO, etc.
Marine AIS Transmissions
I have always meant to receive marine AIS transmissions. You can think of this like an ADSB, but for boats instead of aircraft. Unfortunately, I’m not close enough to the water in Sydney to be able to receive them, so I’ve never actually been able to do it.
With a harbour-view room, I had no excuse not to try to receive AIS. I was able to use OpenCPN, AISMon, SDR#, and Virtual Audio Cable together to make a working, although crude, AIS system. For the record, I did try to receive ADSB as well, but unfortunately, without a clear view of the sky, there wasn’t much action on the screen.
The first step is to tune into the AIS frequency in NFM mode using SDR# and the RTL2832U. Unfortunately, there are two frequencies for AIS, and the best reception uses both of them. I only had equipment for one, so I stayed with just one frequency. As transmissions are done on alternate frequencies to avoid jamming, this means the AIS display will be slower to build and more likely to miss an update here or there.
The audio, unfiltered, is piped through the Virtual Audio Cable into the free decoder, AISMon.
AISMon seems to like having a serial output, so on a laptop without a serial port, it does throw an error but continues to work correctly. Unfortunately, outputting to a LogFile doesn’t seem to work and causes the application to crash. UDP output is used to link this to the plotting software, OpenCPN.
I didn’t bother working out all the details with maps or anything, as you would with serious usage. Instead, I just wanted a display to show me the boats, and a list of the details as well.
On one of my outing days, I decided to leave my laptop catching AIS, and recording the screen. Playing back the day’s recording at accelerated speed allows you to appreciate the AIS plot better, although in reality, it is slow to build and slow to update (especially in poor signal conditions).
It was actually quite interesting and useful, because we could often see the ships moving and identify them before they came into our field of view at the hotel. This gave us a little heads-up as to what to expect “around the corner”.
Over time, I captured some screenshots of each of the boats that I saw, along with their unique MMSI number. This is like a “MAC address” for an AIS transmitter boat. Collecting them, along with their text identifiers, allowed me to build this table.
|HANJIN DALLAS||218061000||Inmarsat B, C or M||Germany|
|SANTA BELINA||229980000||Inmarsat B, C or M||Malta|
|EVER LOADING||235102681||Inmarsat A, Other||UK|
|AZAMARA QUEST||256216000||Inmarsat B, C or M||Malta|
|Unknown||304038000||Inmarsat B, C or M||Antigua and Barbuda|
|MINERVA||309477000||Inmarsat B, C or M||Bahamas|
|STAR PISCES||311000164||Inmarsat A, Other||Bahamas|
|SUPERSTAR VIRGO||311000165||Inmarsat A, Other||Bahamas|
|STARRY METROPOLIS||339300680||Inmarsat C||Jamaica|
|HYUNDAI COURAGE||352698000||Inmarsat B, C or M||Panama|
|IS CHINA||356247000||Inmarsat B, C or M||Panama|
|SEROJA EMPAT||356575000||Inmarsat B, C or M||Panama|
|HANJIN CHENNAI||357079000||Inmarsat B, C or M||Panama|
|DONG TENG||372837000||Inmarsat B, C or M||Panama|
|FI TAT||412000000||Inmarsat B, C or M||China|
|MIN TAI 3 HAO||412441060||Inmarsat C||China|
|SHUN DE||412460910||Inmarsat C||China|
|ZHONG SHAN||412461640||Inmarsat C||China|
|PENG LAI HU||412462060||Inmarsat C||China|
|NAN SHA NO.68||412462570||Inmarsat C||China|
|QI JIANG||412464160||Inmarsat C||China|
|HAI MAN||412468690||Inmarsat C||China|
|XIN YUN TONG 288||412470150||Inmarsat C||China|
|YUE AN YUN 62||412470740||Inmarsat C||China|
|JIN YUAN LUN 8||412475020||Inmarsat C||China|
|YU SHENG658||412476170||Inmarsat C||China|
|SHI TAI 628||412476240||Inmarsat C||China|
|YI XIAN HU||412689000||Inmarsat B, C or M||China|
|CUI HENG HU||412868000||Inmarsat B, C or M||China|
|Unknown||412876000||Inmarsat B, C or M||China|
|SHUNJING||412882000||Inmarsat B, C or M||China|
|XING ZHONG||412884000||Inmarsat B, C or M||China|
|TONG CHENG 602||413465430||Inmarsat C||China|
|FU XING DA 9||413465530||Inmarsat C||China|
|HUI WAN 016||413471130||Inmarsat C||China|
|PING YE 8||413472590||Inmarsat C||China|
|NAN HANG 787||413474470||Inmarsat C||China|
|DONG PENG [email protected]@@@@@@C\||413690270||Inmarsat C||China|
|EN CHENG||413695260||Inmarsat C||China|
|JIAN_GONG_218||413762706||Inmarsat A, Other||China|
|BAI FU 198||413900599||Inmarsat A, Other||China|
|YUEGUANGZHOUHUO0883||413900892||Inmarsat A, Other||China|
|ZHONG HANG 913||413900903||Inmarsat A, Other||China|
|QIAOYANG6HAO||413902224||Inmarsat A, Other||China|
|Unknown||413902778||Inmarsat A, Other||China|
|Unknown||413904053||Inmarsat A, Other||China|
|KMTC SHANGHAI||441902000||Inmarsat B, C or M||Korea|
|KADIMOS||456730000||Inmarsat B, C or M||Unknown|
|GUIA||477012000||Inmarsat B, C or M||Hong Kong|
|PICO||477031000||Inmarsat B, C or M||Hong Kong|
|SANTA MARIA @@@@@@BL||477032000||Inmarsat B, C or M||Hong Kong|
|Unknown||477056200||Inmarsat C||Hong Kong|
|UNIVERSAL MK2012||477056300||Inmarsat C||Hong Kong|
|Unknown||477064000||Inmarsat B, C or M||Hong Kong|
|SHENYANG||477195500||Inmarsat C||Hong Kong|
|MARCO POLO||477197200||Inmarsat C||Hong Kong|
|CASTELLA SQUARE||477197400||Inmarsat C||Hong Kong|
|DI MODA SQUARE||477197500||Inmarsat C||Hong Kong|
|UNIVERSAL MK3||477210000||Inmarsat B, C or M||Hong Kong|
|SHANTOU||477249000||Inmarsat B, C or M||Hong Kong|
|UNIVERSAL MK 2001||477303000||Inmarsat B, C or M||Hong Kong|
|OOCL LONG BEACH||477316000||Inmarsat B, C or M||Hong Kong|
|UNIVERSAL MK2016||477320600||Inmarsat C||Hong Kong|
|UNIVERSAL MK2017||477320700||Inmarsat C||Hong Kong|
|BARCA||477357000||Inmarsat B, C or M||Hong Kong|
|SHANGHAI||477770800||Inmarsat C||Hong Kong|
|WHAMPOA||477847300||Inmarsat C||Hong Kong|
|THEGRANDCANALSHOPPES||477937100||Inmarsat C||Hong Kong|
|THE VENETIAN||477937200||Inmarsat C||Hong Kong|
|COTAI CENTRAL||477937400||Inmarsat C||Hong Kong|
|THE PLAZA||477937700||Inmarsat C||Hong Kong|
|COTAIARENA||477937800||Inmarsat C||Hong Kong|
|COTAISTRIP COTAIGOLD||477937900||Inmarsat C||Hong Kong|
|GOURMET DINING||477958100||Inmarsat C||Hong Kong|
|FIRST FERRY V||477995027||Inmarsat A, Other||Hong Kong|
|FIRST FERRY VII||477995029||Inmarsat A, Other||Hong Kong|
|FIRST FERRY X||477995032||Inmarsat A, Other||Hong Kong|
|FIRST FERRY [email protected]@@@B=||477995033||Inmarsat A, Other||Hong Kong|
|DISCOVERY BAY 1||477995038||Inmarsat A, Other||Hong Kong|
|DISCOVERY BAY 2||477995039||Inmarsat A, Other||Hong Kong|
|DISCOVERY BAY 7||477995042||Inmarsat A, Other||Hong Kong|
|PILOT20||477995051||Inmarsat A, Other||Hong Kong|
|PILOT 1||477995053||Inmarsat A, Other||Hong Kong|
|PILOT 3||477995055||Inmarsat A, Other||Hong Kong|
|PILOT22||477995056||Inmarsat A, Other||Hong Kong|
|PILOT23||477995057||Inmarsat A, Other||Hong Kong|
|PILOT 9||477995061||Inmarsat A, Other||Hong Kong|
|MAN [email protected]@@@@@@@@@@C7||477995062||Inmarsat A, Other||Hong Kong|
|MAN [email protected]@@@@@@@@@@CL||477995063||Inmarsat A, Other||Hong Kong|
|MAN KAI||477995064||Inmarsat A, Other||Hong Kong|
|Unknown||477995073||Inmarsat A, Other||Hong Kong|
|SEA SUPREME||477995074||Inmarsat A, Other||Hong Kong|
|SEA SUPERIOR||477995075||Inmarsat A, Other||Hong Kong|
|SEA SPRING||477995077||Inmarsat A, Other||Hong Kong|
|SEA SMART||477995079||Inmarsat A, Other||Hong Kong|
|PILOT 5||477995084||Inmarsat A, Other||Hong Kong|
|PILOT15||477995091||Inmarsat A, Other||Hong Kong|
|PILOT11||477995106||Inmarsat A, Other||Hong Kong|
|PILOT18||477995109||Inmarsat A, Other||Hong Kong|
|PILOT82||477995123||Inmarsat A, Other||Hong Kong|
|PILOT83||477995124||Inmarsat A, Other||Hong Kong|
|PILOT85||477995126||Inmarsat A, Other||Hong Kong|
|PILOT88||477995128||Inmarsat A, Other||Hong Kong|
|SHUN TAT 31||477995191||Inmarsat A, Other||Hong Kong|
|SHUN TAT 22||477995204||Inmarsat A, Other||Hong Kong|
|PILOT33||477995228||Inmarsat A, Other||Hong Kong|
|WING HOP LEE NO 8||477995245||Inmarsat A, Other||Hong Kong|
|SEA SPEED||477995251||Inmarsat A, Other||Hong Kong|
|MD312||477995257||Inmarsat A, Other||Hong Kong|
|SEA SPIRIT||477995260||Inmarsat C||Hong Kong|
|GEOWORKS SB-1||477995332||Inmarsat A, Other||Hong Kong|
|ANESUN||477995337||Inmarsat A, Other||Hong Kong|
|DIVINGSUPPORT VESSEL||477995389||Inmarsat A, Other||Hong Kong|
|PILOT36||477995390||Inmarsat C||Hong Kong|
|PILOT35||477995392||Inmarsat A, Other||Hong Kong|
|WING ON TRAVEL||477995405||Inmarsat A, Other||Hong Kong|
|WAN HAI 313||565132000||Inmarsat B, C or M||Singapore|
|KOTA SATRIA||565334000||Inmarsat B, C or M||Singapore|
|TEMPANOS||636014648||Inmarsat A, Other||Liberia|
|CSAV TYNDALL||636016321||Inmarsat A, Other||Liberia|
|HS PARIS||636092461||Inmarsat A, Other||Liberia|
|H.K.HARBOUR||900001236||Inmarsat A, Other||Unknown|
|H.K.UNITED 7 B1244||900022890||Inmarsat C||Unknown|
I didn’t realize that the MMSI number follows conventions which reveals the country of registration and (used to accurately show) the satellite equipment on-board. At least, I can say that I’ve been able to receive and decode AIS signals.
It seems that none of the Star Ferry boats carry AIS, but the First Ferry boats do. There seems to be a lot of harbour pilot boats – many more than I expected, which really goes to show just how busy Hong Kong is. A lot of the traffic is heavy freighters.
One of the most interesting souvenirs was this torn fragment of police tape, left behind on a bridge pole. Apparently, earlier in the day, a person had attempted to commit suicide by jumping off the bridge near the hotel and the tape was used to cordon off the area.
Well, at night, we went back to the bridge to take a few shots of the lights, as it was already new year and they would soon be turned off. It wasn’t a particularly scenic area, spoilt by low-pressure sodium lamps.
The traffic in Hong Kong is immense though, and that proved to be a good opportunity for a long-exposure.
Feeling a little disappointed, we went to Central Plaza to get some other shots. Unfortunately, the baubles on the tree weren’t shiny enough …
Anyhow, we continued down to Great Eagle Centre, where some very interesting light made an appearance.
The roadway is bathed in a blue and purple tone, which gives the green trees an eerie, desaturated look. The low-pressure sodium lamp on the left gives the impression of a “sun”, and the sky is a dark, inky colour. One of my favourite shots.
The centre is home to a large bus terminal and interconnection bridge to the Star Ferry terminal.
Walking along the bridge allowed us to get closer to the ferry terminal and take a photo of another Christmas illumination.
So, why the strange coloured lights? Well, the whole area is lit by two massive lighted signs. A red Hitachi sign, and a blue and white China Mobile sign. These seem to be made of many many flourescent tubes, which can be seen in the full sized image..
This also gave me the opportunity to take this photo, which looks a bit “half and half”.
This outing helped break the monotony of spending a few days in the hotel room, not being able to walk.
I’ve come to the end of my radio adventures in the room. This brings us up to about 4th January, so there’s still quite a few more days of the holiday to go. More photos, and less technology, to come in the next few parts!