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Koos van den Hout

Welcome. This is my homepage where I write about my opinion, projects, things I note, things I try and other random stuff. Newsitems have tags for a bit of structure.

Latest news/thoughts/geeking/rants/notablog

2014-04-23 (#) 11 hours ago
I just noticed: LituanicaSAT-1 FM transponder test - Amsat UK which mentions an upcoming test of the FM transponder on Lituanicasat-1 tomorrow April 24th between 13:30 UTC and 15:00 UTC. And I may be able to at least listen to one pass in that time period, there is a pass for me between 13:55 and 14:05 UTC with max elevation 47⁰. Would be really nice if the transponder would still be active the next pass since that will be at max elevation 84⁰.

After updating gpredict does know about the orbital elements of Lituanicasat-1 but not about the transponder. So I added that myself. The format of the .trsp files isn't very complicated, so I created /home/koos/.config/Gpredict/trsp/39571.trsp with:
[Mode V/U FM Voice]
DOWN_LOW=435175500
UP_LOW=145950000
MODE=FM, PL 67.0 Hz

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2014-04-22 (#) 1 day ago
Combining a websdr with fldigi gives me great views of PSK31 traffic, but this evening I also tried receiving APRS, with the audio routed from the java plugin to fldigi using padsp multimon. This crashes a lot, but disabling the scope helps, padsp multimon -s SCOPE. But the 2 meter signal from HF/VHF/UHF WebSDR at the Maxwell Foundation in Eindhoven was too noisy and had interference from other signals to decode anything. I have listened to 2 meter stations via this websdr just fine so I think this could work when the current interference is gone.

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2014-04-18 (#) 5 days ago
Another ISS pass and I was already aware the orbit may be changing a bit since gpredict and hamsatdroid were disagreeing on the time of the pass.

And indeed, the ISS pass started around the later time from gpredict. I heard the AFSK data clearly. The signal from the ISS is strong enough that I can receive it most of the pass with the arrow antenna just pointing directly up. Maybe I can use this to record an entire pass and decode the AFSK data.

I guess celestrak.com (used by gpredict by default) is better up to date than amsat.org (first option in hamsatdroid). Since hamsatdroid can also use the celestrak.com data I switched to this source. The fun part is that satellite names aren't the same. 'SO-50' according to amsat is 'SAUDISAT 1C (SO-50)' according to celestrak.

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2014-04-18 (#) 5 days ago
A bit of searching later found the right incantation to make gnuplot adjust color based on a third value (signal level in my case). It isn't very complicated:
set size square
set angles degrees
set polar
set grid polar 30
set xtics axis 0,30
set ytics axis 0,30
unset border
unset param
set xrange[-90:90]
set yrange[-90:90]
set rrange[0:360]
set trange[0:90]

set title "GPS satellite tracks"
set xlabel "Azimuth"
set ylabel "Elevation"
set terminal png size 600,600
set output "gpsazelsig.png"
plot "gpsazelsig.dat" using 1:2:3 palette notitle
But the resulting plot isn't very helpful for my original question: in which direction radio signals are obstructed. There are some obstructions in the Southwest, but they are comparable to what is in the Northeast.

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2014-04-16 (#) 1 week ago
I want to get an idea of the 'radio shadow' around our backyard to get a better idea of the minimum elevation to receive from and transmit to amateur radio satellites. Since there still is a gps receiver on the roof of the shed and the earlier ntp experiments aren't running at the moment I decided to stop ntp and log the $GPGSV GPS satellites in view messages from the gps unit. My idea is that the radio signals from GPS satellites get obstructed by houses at least the same as UHF signals, so a GPS satellite reception plot will be interesting. Something like the VisualGPS plot I made at a previous house with a different GPS unit. Note that the plotted satellite tracks are way outside the plotted contour which I recall was a nice approximation of the view during the test.

Now to get this data plotted with gnuplot in a polar plot. I found out the orientation of $GPGSV messages (true north is 0 degrees, east is 90 degrees, south is 180 degrees, west is 270 degrees) does not match the azimuth range available by the polar plot in gnuplot (0 degrees is to the right, 90 degrees is up, 180 degrees is to the left). And the horizon is 0 in $GPGSV messages and maximum range in gnuplot. Time for some perl massaging of the $GPGSV lines to gnuplot orientation:
#!/usr/bin/perl -w

use strict;

while (<>){
    chomp;
    if (/^\$GPGSV,\d+,\d+,\d+,([\d,]+)\*[0-9A-Z]{2}$/){
        my @fields=split(/,/,$1);
        while ($#fields>0){
            my $sv=shift @fields;
            my $elevation=shift @fields;
            my $azimuth=shift @fields;
            my $signal=shift @fields;
            if ($signal){
                warn sprintf "SV %d elevation %d azimuth %d signal %d\n",$sv,$elevation,$azimuth,$signal;
                $azimuth=90-$azimuth;
                if ($azimuth<0) {
                    $azimuth+=360;
                }
                printf "%3d %3d\n",$azimuth,90-$elevation;
            }                   
        }               
    }           
}       
And indeed we have data:
SV 33 elevation 27 azimuth 205 signal 38
SV 29 elevation 83 azimuth 100 signal 44
SV 31 elevation 48 azimuth 227 signal 45
SV 21 elevation 47 azimuth 169 signal 44
SV 25 elevation 29 azimuth 122 signal 41
And azimuth/elevation in a file that gnuplot can handle:
245  63
  8   9
283  40
226  44
326  64
The azimuth/elevation data, modified for gnuplot. And the next step is a gnuplot plotscript:
set size square
set angles degrees
set polar
set grid polar 30
set xtics 30
unset border
unset param
set xrange[-90:90]
set yrange[-90:90]
set rrange[0:360]
set trange[0:90]

set title "GPS satellite tracks"
set xlabel "Azimuth"
set ylabel "Elevation"
set terminal png size 600,600
set output "gpsazel.png"
plot "gpsazel.dat" using 1:2 notitle
Which indeed gives a nice plot of some recent data.

Main conclusion: this sirf star II gps is 'too good' for this application. For example, one measurement:
SV 5 elevation 4 azimuth 86 signal 37
Satellite 5 seen at an elevation of 4 degrees above the horizon in easterly direction with a signal/noise ratio of 37 dB. There are high buildings (4 floors) in the easterly direction so I think I'm seeing the gps receiver being way too good at this.

The good part is that I'm not the first one to think of this: GPS Skyline: A Panorama in 1.6GHz Microwave-"Light" which suggests I need to find the right cutoff value for my type of GPS unit.

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2014-04-16 (Another nice video of how to work amateur satellites. He mentions +K7AGE and his videos on working amateur...) 1 week ago
Google+Koos van den Hout : Another nice video of how to work amateur satellites. He mentions +K7AGE and his videos on working amateur satellites.
On programming an HT: I have my Wouxun KG-UVD1P programmed with several adjacent memories for SO-51, each with a doppler-shifted UHF frequency for receive and the VHF frequency+PL tone for transmit. The programming software (chirp) calls these 'split' memories.
2014-04-15 (#) 1 week ago
Modern times, attacks on hosts via both IPv4 and IPv6:
Apr 15 15:23:56 greenblatt kernel: [4741660.011622] FW reject: IN=ppp0 OUT= MAC= SRC=175.44.9.137 DST=82.95.196.202 LEN=48 TOS=0x00 PREC=0x00 TTL=115 ID=6517 DF PROTO=TCP SPT=49363 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Apr 15 15:23:57 greenblatt kernel: [4741660.370701] FW reject: IN=ppp0 OUT= MAC= SRC=175.44.9.137 DST=82.95.196.202 LEN=48 TOS=0x00 PREC=0x00 TTL=115 ID=8371 DF PROTO=TCP SPT=49363 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Apr 15 15:23:58 greenblatt kernel: [4741660.768693] FW reject: IN=ppp0 OUT= MAC= SRC=175.44.9.137 DST=82.95.196.202 LEN=48 TOS=0x00 PREC=0x00 TTL=115 ID=10428 DF PROTO=TCP SPT=49363 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Apr 15 15:23:58 greenblatt kernel: [4741660.924225] FW reject: IN=ppp0 OUT= MAC= SRC=2002:af2c:0989:0000:0000:0000:af2c:0989 DST=2001:0980:14ca:0042:0000:0000:0000:0018 LEN=68 TC=0 HOPLIMIT=120 FLOWLBL=0 PROTO=TCP SPT=50764 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Apr 15 15:24:01 greenblatt kernel: [4741662.117101] FW reject: IN=ppp0 OUT= MAC= SRC=2002:af2c:0989:0000:0000:0000:af2c:0989 DST=2001:0980:14ca:0042:0000:0000:0000:0018 LEN=68 TC=0 HOPLIMIT=120 FLOWLBL=0 PROTO=TCP SPT=50764 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Apr 15 15:24:07 greenblatt kernel: [4741664.510439] FW reject: IN=ppp0 OUT= MAC= SRC=2002:af2c:0989:0000:0000:0000:af2c:0989 DST=2001:0980:14ca:0042:0000:0000:0000:0018 LEN=68 TC=0 HOPLIMIT=120 FLOWLBL=0 PROTO=TCP SPT=50764 DPT=21 WINDOW=8192 RES=0x00 SYN URGP=0
Same source via IPv4 and IPv6 with 6to4.

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2014-04-15 (#) 1 week ago
It has been ages since I wrote about pump'n'dump spam where spammers try to inflate prices of stock for their own personal gain. It looked like the problem had almost gone away, but the last few weeks one stock is spammed again. Someone is set on making a profit or at least investing money in minimizing the damage with the RCHA stock (Rich Pharmaceuticals, Inc) and has been at it since at least 4 April 2014 now.

Dynamoo has a good write-up: RCHA / Rich Pharmaceuticals, Inc pump-and-dump spam - Dynamoo with graphs. Stock price and volume is following the pattern of a pump and dump scam.

Even the company itself is now reporting about the spam: Rich Pharmaceuticals Warns Investors of Unauthorized Spam Stock Promotion - Press release via Reuters. I consider the stock market a form of gambling anyway so I'll skip the links to "serious" stock advice about the RHCA stock.

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2014-04-14 (#) 1 week ago
When documenting something I have to look up the full path of some file and have it ready for cut-and-paste. I found out the easy way to canonicalize a filename:
koos@greenblatt:~$ readlink -f ../../etc/radvd.conf
/etc/radvd.conf

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2014-04-14 (#) 1 week ago
This evening had no high Saudisat SO-50 passes at friendly times but it did have a nice overhead ISS pass around 22:15 localtime. I noticed the AFSK signal later than I expected according to the azimuth/elevation calculated by gpredict and reception stayed fine when gpredict said elevation had dropped to about 1 degree above the Eastern horizon. There are high buildings in this direction, so I guess the orbit has changed a bit compared to the latest data I had. AFSK reception was fine, maybe I should try to record the outgoing audio somehow so I can decode it later.

I have programmed the ISS region 2 voice frequency from the ISS Frequencies - ISS Fan Club into my radio so I could hear voice communications or even try to make a contact when the ISS is overhead. Reading the Recorded ISS radio contacts - ISS Fan Club page shows some radio amateurs have been trying that for 2 years before succeeding so it won't happen easily.

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2014-04-07 (#) 2 weeks ago
Trying to hear and work the SO-50 satellite as PD4KH portable has one downside: certain types of weather don't agree. The first pass this evening was really nice, straight overhead. But closer to earth there were serious rainclouds overhead causing a downpour so I opted to skip that one. A pass later in the evening started dry so I went outside. During the pass it started to rain again a bit so I had to dry my laptop after I was done! It was a low West-North pass and those are harder to follow from our house. But I did hear some voices and I think I understood at least one callsign, but checking the live oscar satellite status page shows no callsign matching what I think I heard.

Update 2014-04-08: Another nicely timed West-North pass, without rain this time. I heard some interference, including someone who decided that whistling at the satellite was a good idea. Probably taken directly from the "what NOT to do with amateur satellites" handbook.

The pages maintained by Mike Rupprecht DK3WN about amateur satellites have some realaudio samples of good and bad use of the amateur satellites: SaudiSat 41, 42, 50 - Mike Rupprecht - Amateurfunk Betrieb über FM Satelliten - Mike Rupprecht - Amateurfunk I don't agree with the quoted statement by LA2QAA in the last article of being proud of never using the "easy" FM amateur satellites. A more positive approach is needed in my opinion.

One "mental" switch I have a problem with: with the squelch completely open I hear noise when I'm either not listening to the satellite or the satellite is not in use by another amateur. With listening to "earth" FM repeaters at normal squelch settings I'm used to noise meaning that someone is trying to use the repeater but failing. This means pressing the transmit button when hearing noise on the satellite is a bit "unnatural" to me.

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2014-04-06 (+Hans PD0AC writes about chirp (tested under Linux, which is also what I use). I couldn't agree more...) 2 weeks ago
Google+Koos van den Hout : +Hans PD0AC writes about chirp (tested under Linux, which is also what I use). I couldn't agree more with him, it's a great program to edit memory channels and extra options in lots of radios.
And I never have to boot into Windows just to fix a memory channel on my radio.
2014-04-06 (#) 2 weeks ago
The fact I can't get status information from the fritz.box such as linespeed in a way I can use in scripts annoy me, especially since the linespeed changed tonight (to 22381 down 1402 up). I'd like to at least have access to those statistics for my pretty graphs again. I did find Universal Plug and Play How to get Status-Information from the FRITZ!Box which uses the Perl Net::UPnP::ControlPoint module. The downside is this module wants to discover upnp devices by itself via multicast. So I need to setup a specific route for 224.0.0.0/4 from the server. It does discover the Fritz!Box, but thinks it has no further information:
$ ./get_upnp_info.mcast .
Device = FRITZ!Box Fon WLAN 7360
No possible actions. Digging a bit into the code reveals the problem is probably in the XML parsing bit. Changing the xml parser to search in namespace urn:dslforum-org:service-1-0 gives a tiny bit more:
$ ./get_upnp_info.mcast .
Device = FRITZ!Box Fon WLAN 7360
URL = http://192.168.178.1:49000/l2tpv3SCPD.xml
urn:any-com:serviceId:l2tpv31::GetInfo:ServerInstanceId = 0000001F8BF6F4502F99CFB2F71DC374ECD623A957E08803247CDC9AD3856FF4DDA943C535C22E937DE07643AB2A6BBFEC45DED2FBF0E95AC5C2B3B28699F07
urn:any-com:serviceId:l2tpv31::GetInfo:ServerIP = 192.168.178.1
urn:any-com:serviceId:l2tpv31::GetInfo:RemoteEndIds = fritz.box:guest
But no DSL upstream and downstream yet.

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2014-04-03 (I recently bought myself an arrow satellite antenna and tried it a few times, trying to receive SO-50...) 2 weeks ago
Google+Koos van den Hout : I recently bought myself an arrow satellite antenna and tried it a few times, trying to receive SO-50. And wrote about the experiences.
2014-04-02 (#) 3 weeks ago
I ordered and received an Arrow Antenna: hand held portable dual band 2m/70cm Yagi satellite antenna. It came in last Saturday afternoon. And now I constantly look at the amateur satellite trackers on my laptop and tablet to see when passes come up for satellites that I can receive in FM. First receiving: I don't want to be the proverbial alligator on the amateur satellites (all mouth and no ears).

Our house being in a quite built-up area means when the elevation doesn't get above around 20 degrees there will not be a lot of chance to receive the satellite.

What I am looking for is satellites I can receive (and work) with the FM handheld transceiver. I focus on Saudisat-1c, the International Space Station and Oscar-11. Oscar-11 is an older amateur satellite but I could be lucky with receiving telemetry in AFSK format.

This evening had an 'easy' pass of Saudisat-1c usually known as SO-50, straight over my head. The obvious upside is: no buildings in the way. The less obvious upside: a shorter distance to the satellite, less signall loss. With headphones to hear the incoming audio in both ears I was able to hear callsigns. I'm not sure I heard a complete QSO. What I learned was that the moment the reception is clearest (shortest radio path) is also the moment of the biggest Doppler shift in receive frequency.

I also had a reasonably easy pass Saturday evening. I reported both passes to the OSCAR Satellite Status page by KD5QGR.

Update 2014-04-04: This evening I heard the AFSK1200 noises from an ISS pass! Amazing how fast the enormous mass of the International Space Station flies across the horizon. In 6 minutes it passed from azimuth 218⁰ (southwest) to 80⁰ (north of east).

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2014-04-02 (#) Configuratie voor VDSL van xs4all met het eindpunt op een linux server 3 weeks ago
Mijn configuratie is natuurlijk gebaseerd op PPPoE passthrough op Fritz!Box 7360 voor XS4all VDSL maar ik gebruik (Ubuntu) Linux. Mijn huidige /var/flash/debug.cfg op de Fritz!Box 7360: sleep 120 killall dsld sleep 10 brctl addif lan ptm_vr9 ifconfig ptm_vr9 up De Fritz!Box 7360 hangt aan een 802.1q geschikte switch die vlan 2 native en vlan 6 tagged accepteert op deze poort. Uiteindelijk komen beide vlans uit ...
Read the rest of 'Configuratie voor VDSL van xs4all met het eindpunt op een linux server'
2014-04-01 (#) 3 weeks ago
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References

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No I didn't and I'm not going to follow that "unsubscribe" link. Interesting how this spam shows up on lots of sites that seem to automatically convert e-mail into website posts.

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2014-03-29 (#) 3 weeks ago
Looking at the DSL spectrum of the new VDSL modem I noticed the used frequencies overlap with spectrum used by AM broadcast stations. With a few stations in the area that transmit at reasonable amounts of power, I thought this might be a source of interference. Someone who lives close to the AM transmitter near IJsselstein has noticed the carrier containing 675 kHz isn't used, the frequency of the nearby AM transmitter. Found at HF-dichte modem/router gezocht - zendamateur.com forum in Dutch

When I searched whether someone had looked into this matter before me I found A VDSL tutorial by Frank Sjöberg which notes:
The main source of RFI is believed to be amateur radio (HAM) transmitters. This is because they can be located just a few meters from a telephone line and the transmitting power can be relatively high - up to 400 W in the UK and 1.5 kW in the USA. Even though AM broadcast transmitters use much higher transmit power, they are usually not located so close to the telephone wires. The number of active AM transmitters is also quite small compared to the number of amateur radio users, especially in Europe. Furthermore, AM-broadcast transmitters always transmit the carrier wave, which makes them more stationary and easier to deal with, compared to amateur radio users that can change frequency often and mostly transmit single side-band (SSB) modulated signals.
From a DSL viewpoint amateur radio is indeed unpredictable and a strong source of interference. Time for fiber.

I don't transmit on HF yet, so I don't have any personal experience yet. Looking at the signal/noise ratio graph from the modem there may indeed be a small dip in signal/noise ratio around 675 kHz.

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2014-03-26 (#) 4 weeks ago
Eerste stap met het VDSL modem, een Fritz!Box 7360 is een firmware upgrade (om zo betere VDSL snelheid te halen). En wat blijkt, het modem wil perse via z'n "eigen" internet verbinding updaten, en op de avm site staan de updates ook niet zomaar ter download. Na wat zoeken, het is een 7360_v1, en dus staat de firmware in ftp://ftp.avm.de/fritz.box/fritzbox.fon_wlan_7360_v1/firmware/english/. Upgrade gereed, nu de rest van de VDSL config waarvoor ik de telnet poort open moet zetten.

Telnet open zetten gaat met een analoog telefoontoestel. Daarna kan het /var/flash/debug.cfg bestand aangepast worden. Hoewel ik de meeste instructies uit PPPoE passthrough op Fritz!Box 7360 voor XS4all VDSL gebruik vond ik de aanpak in xs4all-pppoe-fb7360/debug.cfg at master · antonyantony/xs4all-pppoe-fb7360 · GitHub net even mooier, dat script blijft rondjes draaien tot de zaak goed opkomt en houdt daarna de status in de gaten.

Update 2013-03-28: Ergens in de config zat een fout die er een puinhoop van maakte en toen moest ik zelfs een recovery image gebruiken om weer toegang te krijgen. Dus maar in kleinere stapjes de zaak weer geconfigureerd. Nu werkt het, ik werk nu met de iets simpeler stapjes in /var/flash/debug.cfg.

Oh en de lijn statistieken: 21899 kilobit down, 1436 kilobit up, VDSL2 profiel 8b. Ik ben benieuwd of DLM hier nog dingen aan verbeterd (meer upstream mag). Grappig was dat de vantevoren verwachte waarden waren ~ 18000 kilobit down, ~ 4000 kilobit up, dus de lijn gedraagt zich in eerste instantie anders.

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Father, cat owned/owner, Unix/Linux fan, Internet user, reader, recumbent byciclist, snowboarder, ipv6 fan. For those who don't speak Dutch: how to pronounce Koos van den Hout.

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Specialist information security at Utrecht University with a modern Profile page.
 

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Koos van den Hout, reachable as koos+website@koos.idefix.net. PGP key DSS/1024 2C66 3B5D F0D7 C263 via keyservers PGP key DSS/1024 2C66 3B5D F0D7 C263 local copy pgp key statistics for 0x2C663B5DF0D7C263 Koos van den Hout
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