News items for tag dvb - Koos van den Hout

2012-06-15 (#)
Noticeable in the DVB-T services scan for 20120608: One digitenne multiplex 2 has moved from 826 MHz to 594 MHz. Part of the clearing of 800-900 MHz in the Netherlands. The other multiplex at 818 MHz will probably move at some time this year.

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2012-06-11 (#)
I recently got access to a Motorola SBV5121E cablemodem. No, I'm not switching to cable Internet access at the moment as ziggo still doesn't offer fixed IPv4 addresses or IPv6 at all on consumer connections. But it was interesting to give the cable modem a try.

If I am correct, this is the 'previous' generation cable modem. The maximum speed on the ethernet interface is 100 Megabit where Ziggo now offers subscriptions up to 120 Megabit.

When not connected to the cable network, the modem runs a small DHCP server for IPv4 which gives out 192.168.100.x addresses. The management interface is reachable via, username admin password motorola.

When I connect the RF interface to the tv cable, it gets a link. In the management interface I see Downstream frequency 186000000 Hz (186 MHz) with QAM256 modulation. The upstream frequency is 36000000 Hz (36 MHz) and the interface lists QPSK, 32QAM and 64QAM modulation, I guess the fastest one with a reasonable error-rate is chosen. Downstream speed is listed as 55.616 Megabit and upstream speed as 30.720 Megabit.

Interesting to see quadrature amplitude modulation (QAM) used here, just like in the DVB standards. I guess this is the best way to fit bits in a broadcast channel.

Connected to the ziggo cable and running tcpdump shows arp traffic originating from ziggo routers. Trying to cause traffic to ziggo IPv4 addresses from the outside shows arp for only one IPv4 address I tried, not for lots of others. Which means either all those clients are active (needing no ARP try needed) or one IPv4 address to the next being active in separate broadcast domains.

I also ran tcpdump with the modem starting up disconnected at the cable side. Absolutely no packet comes out on the ethernet interface.

First time I tried to get an IPv4 address from cable using DHCP while connected it gave me a IPv4 address from the range, a range "reserved for benchmark tests of network interconnect devices". When I tried to visit any website I got redirected to at / (which is in RFC1918 space). This website identifies itself as activation site for the provider, asking for a provisioning code and password. I guess the activation site will link cable mac and customer account in the databases at the cable operator side.

A scan of the assigned network (a /24 out of shows several IPs in use all having the same MAC address 00:30:B8:xx:xx:xx (RiverDelta Networks). A search for RiverDelta Networks shows it is a maker of cable modem termination systems and has been acquired by motorola.

When I tried it again it with the same cable modem it doesn't give me an IPv4 address at all. An interesting change.

Update: Later another Motorola SBV5121E cablemodem found its way to me. Trying this modem gave me an IPv4 address via DHCP again and a new try at the activation server so I could look up certain things described in this item and update it.

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2012-03-20 (#)
The Noxon DAB USB stick I got as a cheap DAB/DAB+ experimenting device has hidden powers. A big part of the 'cheap' is because this device leaves all of the work to software. If I understand the discussions about the Noxon correctly, there are drivers to receive dvb-t signals with the same stick. Most development for the linux driver seems to be on the dvb-t side too.

I came across a webpage which puts this all in a new light: The whole device turns out to be a wideband tuner and an analog to digital convertor. Software has to do the rest. And now someone has written that software. Some clever thinking and discussion started by Antti Palosaari turned into rtl-sdr, a software defined radio using the RTL2832U chip. Together with my other thoughts about software defined radio where I thought about receiving and decoding D-STAR ham radio signals with for example a funcube dongle this means I already have a software defined radio. Time to capture some I/Q data and learn about gnuradio. The rtl-sdr software has already been used to receive Tetra signals (frequencies UHF 380 MHz .. 476 MHz) and GMR signals (satellite phone, L-band 1600 MHz). So I guess 70cm D-STAR should not be a problem.

Update 2012-03-21:
Spectrum of 3M broadcast band
Simple FFT (spectrum analysis) of data coming from the NOXON dab usb stick. Works in the VHF FM broadcast band, I can see various signals and verify their frequencies. With stronger stations I can use the wideband FM decoder in gnuradio and get audio. Click for full screen capture from gnuradio FFT.
Played with this, and I managed to receive an FM radio station and decode the stereo audio from it using the grc (gnuradio companion) rtl2832 to fm scripts mentioned here. Hearing a bit of radio received and decoded by hardware which absolutely wasn't sold to me with that capability is fun. Everything gnuradio is all new to me so most of the time I have no idea what I'm looking at and the noise in the Noxon stick is causing issues as usual.

Update 2012-03-22: Played some more, and added the plot. And I heard audio from some of the stronger stations. But I still have serious noise issues, even when moving the usb stick away from the computer with a long usb extension cable. As you can see in the plot there is not much difference between the noise level and a strong local station. The wideband FM receiver module available in gnuradio companion couldn't even decode the signal at 93.8 MHz (Slam!FM Noordbrabant) in the captured data.

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2012-03-08 (#)
As mentioned at Ziggo begint met QAM256 - Digitale Kabeltelevisie (Dutch) my cable provider is switching to QAM256 modulation which allows for 8 bits per symbol, from QAM64 which allows for 6 bits. I noticed it today when checking the information for discovery channel. The signal strength is about 55% but the error rate is 0%, so reception is fine. This should give more services at some point in the future, but my best guess those will cost extra money too.

Update 2012-03-13: It's interesting how Ziggo can do this in production (I call it "in production" when a number of running services is only available in QAM256) with tech news sites only picking this up days later. And still calling it a test. Although they probably don't use the extra bandwidth so they can switch back.

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2012-01-05 (#)
It's a bad time for transmitter masts in this country.

According to the article Zendmast Digitenne waait om - (in Dutch)

the mast on the Galghenwert Building in Utrecht has fallen over. The mast is on top of a high office building. As it is a new transmitter that was switched on in the last half year to replace one on another building in the city it was clearly not that hard to switch back. Reception on a dvb-t stick connected to the server in the attic is fine.

My own pictures of that transmitter at Zendlocatie Herculesplein gebouw Galghenwert, Utrecht - pictures by Koos van den Hout
My pictures of the old transmitter at Zendlocatie Burgemeester Fockema Andrelaan, Utrecht - pictures by Koos van den Hout

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2011-12-30 (#)
Browsing the tables for Digitenne at DTV monitor shows the transport stream 12 I noticed still listed. Pick one of the transport streams at the left, and open Tables, NIT-actual, Network ID 8720 (Digitenne). When I try the same on several of the muxes here I get no mention of TS 12 in the network information table. According to DTV monitor the analysis was done today, so some interesting things going on? My best guess is that DTV Monitor does the scanning from somewhere near Den Haag.

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2011-12-24 (#)
With DVB based television it is quite possible to temporarily add a service, given available bandwidth within the transport streams. Service BNN 101.TV is at the moment temporarily available in Digitenne as part of the Serious Request event. The capacity was used earlier for RTV Drenthe after the collapse of the transmitter tower at Hoogersmilde.

3FM Serious Request gratis voor KPN klanten op zender 101TV - KPN news stream (Dutch). The detail missed in this press release is that 101TV on DVB-T (Digitenne) is free-to-air.

Logo Cultura24 via DVB-T capture 2011-12-29 Update 2011-12-29: The next event is now happening: Top2000 editie 2011 is on Radio 2 at the moment and Digitenne now has service Cultura24 with the accompanying live view of the radio studio. So I captured the logo since it is free-to-air.

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2011-12-15 (#)
Tried a few DVB-T service scans today in the rainy weather and unsurprisingly rain degrades the UHF reception. Even the Digitenne Flevoland multiplex wasn't always error-free enough to show in the scan.

DVB-T service scan for 2011-12-15.

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2011-12-04 (#)
I just rescanned the Network Information Table of Digitenne Mux 1 to see if the strange multiplex 12 being listed for digitenne 6 months ago still shows up. It doesn't, the whole transportstream 12 is gone from the NIT. Artefacts of some test by Digitenne?

Listed transport streams:
    Transport_stream_ID: 2211 (0x08a3)
    Transport_stream_ID: 2212 (0x08a4)
    Transport_stream_ID: 2213 (0x08a5)
    Transport_stream_ID: 2214 (0x08a6)
    Transport_stream_ID: 2244 (0x08c4)
DVB-T services scan for 2011-12-04.

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2011-11-21 (#)
Now we have a child growing up, children's television is also something to look at. The program for young children in the Netherlands is Sesamstraat, the Dutch version of sesame street. But it's scheduled at times that we are still on our way home. The solution: connect the dvb-t stick to the server and record there, to be played on the netgear mediaplayer. I first looked at the linux video disc recorder and MythTv but both are a bit too much everything and the kitchen sink for just regularly recording a tv program to be played somewhere else. There are options for Headless VDR mode but as stated the software is optimized for tunerdevices and playing in one box, like a settop box with harddisk recorder.

I asked a bit around and got a good tip from Matt McLeod: a simple script around dvbstream to fetch the video and audio pid from the dvb stream and save the result. Originally dvbstream is designed to take dvbstreams and put them on a (multicast) network, but it can also save to file. I changed the script to use the right settings for the Dutch programs, and it works and the result plays nicely on the netgear eva mediaplayer. My version:

%nets = (
                'NL1', '-qam 64 -cr 1_2 -gi 4 -bw 8 -tm 8 -f 706000',
                'NL2', '-qam 64 -cr 1_2 -gi 4 -bw 8 -tm 8 -f 706000',
                'NL3', '-qam 64 -cr 1_2 -gi 4 -bw 8 -tm 8 -f 706000',

%pids = (
                'NL1-sd', '7011 7012',
                'NL2-sd', '7021 7022' ,
                'NL3-sd', '7031 7032',

$net = shift @ARGV;
$time = shift @ARGV;
$filename = shift @ARGV;
$type = "sd";

#print "$time, $net, $type\n";

$cmd = "dvbstream " . $nets{"$net"} . " -n $time -ps -o " . $pids{"$net-$type"};

system qq($cmd > "$filename");

A 2 minute testrun gave me a 42 megabyte file. If I have it correct, this is a program stream with the video and audio in mpeg-2 format. Which explains why it's quite big for the quality and amount of time recorded. If I want to keep stuff for longer, conversion to better formats will have to be done.

Update: It works as a VCR with a unix commandline interface:
koos@greenblatt:~$ at 17:25
warning: commands will be executed using /bin/sh
at> cd /scratch/sesamstraat
at> ~/webvcr/ NL1 900 NL1-2011-11-22-sesamstraat.mpg
job 73 at Tue Nov 22 17:25:00 2011

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IPv6 check

Running test...
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