I setup a new PC and tried to get Linpac AX25 terminal working again.
This was not so easy since calling some standard functions has changed since the last release of Linpac in 2003. It compiled on a Xubuntu 12.04 system.
If you need the sources just send me a mail. I have put the tgz of the sources to my Download page.
Author Archives: mario
Hiqsdr
Current status of my hiqsdr trx.Preselector with some of the filters, frontend and power supply.
Olympiaturm München
DUR 13-01
January DUR contest.This time from home, 23cm only.
Delta Loop 10m
For the 10m Contest in January i made 2 Delta Loop antennas.
10 Euro SDR from Hongkong
Recently i purchased a cheap RTL2838+ R820T device from a vendor from Hongkong.
The cost was about 10 Euro including shipping.
The video shows some reception with the SDRSharp software.
Tuning range is from about 24MHz to about 1750MHz. I discovered no gaps so far.
RTLSDR from Hongkong (short demo)
Freedv / FDMDV2 – digital voice shortwave
Since a long time David Rowe VK5DGR works on a open-source low-rate voice codec. This project is called codec2.
Now a variant of this codec is used in a amateur radio digital voice mode that was evolved out of the well known FDMDV software.
The mode uses OFDM with 14 carriers DQPSK and 2 pilot carriers with twice the power modulated in DBPSK.
The bandwith is 1kHz, so 2 of the signals would fit to 1 SSB channel. The datarate of the voice is 1375 Bit/s + some data bits for callsign information etc.
Its intended that in the end this mode can also be used for DX connections. Lets see what live tests will bring. On 20m obviously the frequency 14.236MHz is used as center of gravity.
For using the mode you would need either a two-soundcard PC (one for connecting a headset and one for creating the digital modulation signal) or a SDR setup with virtual soundcards. Currently a windows beta release can be downloaded as binary. For Linux you have to download the source and compile it on your own. David created a nice Makefile that downloads and compiles all dependecies.
You find further information on the project page http://freedv.org/tiki-index.php.
Also some videos are linked that show the operation and the audio quality of this digital mode.
some experiments with FreeDV and Quisk
How the digital signal of Freedv/FDMDV2 sounds like:
freedv-test
How the decoded audio sounds like (its only 1375bit/s with 1kHz bandwidth!):
REC-0003
RTLSDR with OpenWRT
Last days i spend some minutes getting the RTL_TCP server running with OpenWRT Backfire on one of my WGT634U routers. These routers have a USB2 port and i can connect my NOXON DAB Stick directly.
I crosscompiled the packages. The sources and a Makefile for the OpenWRT build system you can get from the Osmocom page. You definitively need libusb for getting it running.
For the brcm47xx plattform you can find the both packages here:
librtlsdr_0.1.0-1_brcm47xx.ipk
rtl-sdr_0.1.0-1_brcm47xx.ipk
Attention: The both packages have not been added to my Packages file in the directory. So you have to copy them manually and install them to your OpenWRT. The dependencies are resolved automatically.
After that you probably need to configure the firewall on the router to pass port 1234 to the outside and the RTL_TCP server needs to be started with option -a #lan-interface-ip#, otherise the server will listen to localhost only. With my WGT634U i experienced that i cannot set the samplerate to 2MSpl/s. In this case the router reboots after a few seconds. With 1MSpl/s it worked smooth so far.
With running the server on a embedded system you can install the frontend at a completely different location than the client.
HiQSDR,Quisk,SO2SDR
Just trying a bit with my HiQSDR frontend and Quisk together with SO2SDR.
Jim implemented Rigctrl model 2 to Quisk. This makes it operate with other software like fldigi very well.
SO2SDR is a contest log with SDR bandmap and DXCluster. Worked QSO can be marked in the bandmap as well as stations spotted in the cluster.
Unfortunately I do not get IQ signals from Quisk to SO2SDR yet…
See a screenshot:
Quisk and SO2SDR
Marconi Memorial Contest 2012 – JO60TR
I had the chance to run the MMC 2012 from the QTH of DL4DTU in JO60TR. Special thanks to Norbert !
The antenna was a 8ele and about 400wtts with Norberts TS850 + Transverter.
Since i had no equipment to carry despite a PC for logging and calling i decided to give some monitoring with a SDR solution a try. I used my 20Euro Noxon DAB Stick with SDR# to observe the frequency occupation. Surprisingly this simple device did a fairly good job. Unfortunately i was not able to get my CwSkimmer working again although it worked fine before at home. Because of the high density of stations i faced strong QRM. In the end i had about 230 QSO with about 60k points. Thats a fair result for my first MMC and a single antenna system ;)
The short video shows the PA of Norbert, the USB stick for internet connection, the logging PC, the SDR PC with the Noxon stick and (most important ;) ) the heater.
Marconi Memorial Contest 2012 - DH5YM - JO60TR
Band during MMC12 in JO60TR