Last weeks i tested D-Star. Jan Alte, DO1FJN developed a digital voice modem PCB which can be mounted to the C5 cellphone from Siemens. The modem firmware and the user software that runs on the phone´s microcontroller is still in development but it does quite well already. I made a qso via the repeater DM0MW in Mittweida and also a direct qso with Peter, DL5DTL here in Dresden.
Overall the voice quality of the AMBE codec used in D-Star is not satisfying and FM sounds much better at the same signal level. The advantage of D-Star seems to be that you can carry data while doing a voice qso and you can receive a data channel on a repeater frequency. But is it worth investing the money for that ?
Anyway the modem from Jan is really impressive because the firmware is open source and it features a AVR32 microcontroller as well as an CPLD which enables to implement also other standards like APCO25, POCSAG or Packet Radio on it. Sounds it can be an interesting platform for implementing new ideas.
Author Archives: mario
Gallery of my Laser station
I created a small gallery that shows some pictures of my laser station. Find it here:
Laser station gallery
Webserver statistics
I used Analog to analyze the logfile of my HTTP server. Find below the interesting statistic via which search words the webserver was found. I do not have too much information about the DG8SAQ VNWA at my pages by the way.
Searchwords to find my server
HDLC/AX25 to serial KISS converter
Last day´s i continued working on my HDLC/AX25 KISS TNC software. It is far away from beeing finished but may be useful for someone already.
What´s it ?: You can connect an RF modem with NRZ or NRZI coded output. I just tested 1k2 and 9k6 bps AX25 modems. The microcontroller (currently Atmega644) decodes the frames and forwards it to a host PC via a serial KISS interface. This interface supports plain KISS, SMACK and RMNC-CRC-KISS. What´s not in this version is the CRC check for the received packets. This will be one of the next steps.
What it should be somewhen: A complete KISS/SMACK TNC which uses an external modem. Most probably this will not work on a Atmega644 because of the RAM limitations. I try to get it into an Atmega8515 with external SRAM. Another option might be a Atmega1281 or 1284 without external memory. For 1k2 (not sure for 9k6) is would also be possible to add the modem functionality directly to the microcontroller and therefore to safe the external modem.
New digipeater hardware at DB0TUD
End of 2009 we had to install some new hardware at the digipeater DB0TUD (TU Dresden, Suedhoehe). Reason were the outstanding noise generated by powersupply and flexnet PC towards the remote controlled shortwave station. After a failed attempt to replace the old ISA USCC card with a PCIUSCC we installed a OpenWRT based WRT634U system with 2x TNC3 and 1x TNC2C running xnet. This is just a interim solution and will be replaced by DLC7 + TNC3 + TNC2C soon.
DB0TUD running OpenWRT/XNet
EMail Reflektor zu digitalem Amateurfunk in Sachsen
Ich habe heute mal einen eMail Reflektor zu digitalem Amateurfunk (Packet Radio, Hamnet, Funkruf, usw.) angelegt.
Nach einer Registrierung kann man eMails an die Reflektoradresse digafusax@yahoogroups.com schicken, welche dann
automatisch an alle registrierten Nutzer weitergeleitet werden.
Anmelden kann man sich bei http://groups.yahoo.com/group/digafusax
Vortrag zum VNWA2
Zur DUR Treffen am 9.10.2009 habe ich einen kurzen Vortrag zum VNWA2 gehalten. Der Teil ueber die Messungen erfolgte praktisch und ist deshalb im Vortrag etwas kurz gehalten.
At the DUR meeting on 2009/Oct/09 i held a short talk about the VNWA2. The part about measurement’s was a live practice and therefore only covered in the slideset shortly.
Slides in german language only.
My first real world laser contact
Last weekend i participated in the UHF/SHF Contest within the DM7A team from JO60LK (Fichtelberg). The day’s before i completed my laser station. (Mechanical stuff for adjusting the laser diode and modifications for getting modulation working). A first test via reflektion at a house in 500m distance was promising. With Marcel DK5WMA a sked was arranged for saturday afternoon. I mounted the laser transceiver at the Fichtelberg. Marcel’s QTH was the Hirtstein in JO60OM. I adjusted the telescopic sight to the prominent wind wheels at the Hirtstein and switched on the laser. Marcel was able to see the beam immediately. How crazy. The sun was still above the horizont. The test from JO60OM into my direction did not work at first and we decided to wait for sunset. We tried again right after sunset and after some minor adjustments at Marcel’s side the twoway connection was working properly. Amazing to hear the voice over around 20km distance. We both took a photo of the red dot at the other side. Obviously DK5WMA’s camera is much better ;) See some photo’s below.
Laser in JO60LK
DK5WMA as seen in JO60LK, my camera is not that sensitive.
Laser as seen by DK5WMA
Laser Communication
Two days before the next contest at least the mechanical work is almost finished. First tests looking promising. There are still problems with the modulation of the transmitter. Let’s hope for good wheather at the weekend.
Laser Transceiver
Once more Triebenberg
I was once more QRV from the Triebenberg in JO61XA. The activity was a bit sobering but at least the wheather was nice. I got 13 QSO with a ODX of around 100km. Surprisingly there were some local stations active in FM on 1297,5MHz. The week before the contest i modified the transverter to solve the thermal problems with the built-in PA. This works quite well now without running away 10kHz anymore. Additionally i repaired an old 16Ele Yagi i got from DG2DWL. This antenna is around 6dB better than my old bi-quad. The biggest surprise came 15 minutes before the end of the contest. A beep from the voltage converter that supplies the antenna rotor told me that my car’s battery was empty. No chance to start the engine anymore. It was the first time i was happy that there are so much people hiking at the Triebenberg (and of course coming by car beeing able to help me starting my own one) ;)
Hear you next time !
Transverter, FT857D and voice keyer inside the car