HDLC/AX25 to serial KISS converter

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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.

AVR HDLC decoder source

New digipeater hardware at DB0TUD

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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

DB0TUD running OpenWRT/XNet

Vortrag zum VNWA2

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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.

Slides about the VNWA2 (german)

My first real world laser contact

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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

Laser in JO60LK

DK5WMA as seen in JO60LK, my camera is not that sensitive.

DK5WMA as seen in JO60LK, my camera is not that sensitive.

Laser as seen by DK5WMA

Laser as seen by DK5WMA

Once more Triebenberg

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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

Transverter, FT857D and voice keyer inside the car

Laser justification unit

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In order to get the laser communication unit justified for the correct direction it is necessary to have the possibility for fine adjustment of horizontal and vertical angles. I made some progress in building a unit that can be mounted onto a tripod and will cary the laser transceiver in the future. Find some pictures attached below. It’s not finished yet but the horizontal adjustment works fine.

Laser justification unit

Laser justification unit

Laser justification unit

Laser justification unit

DUR Activity contest July 2009

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I participated in the July DUR Activity contest. This time i decided to be qrv from the Triebenberg in JO61XA. Because the hill is not open for everybody (there is an external laboratory of the Technical University of Dresden) i had to build up the antenna at the base of the hill. The Triebenberg is the highest hill in the area of the city of Dresden. The activity during the contest was much better than last time. This was mostly because of the OM´s from DF0MTL beeing active from JO61JF. Therefore i had only few time for 2m operation but i had only a bigwheel antenna with be anyway. At 23cm i am still using my tiny hybrid-quad antenna which appears not to be competitive ;) Next time i might use another QTH and another antenna, of course.  After the contest i had to hurry up because the rain front came close really fast. Two minutes after i had all the stuff in the car heavy rain started.

Hope to hear you next time !

Tiny antennas in JO61XA

Tiny antennas in JO61XA

Dark clouds over the Triebenberg

Dark clouds over the Triebenberg

Laser Communications (2nd)

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I assembled the PCB´s for the DL2CH laser transceiver and did some basic tests using a ordinary LED as signal source. The lens is a 90mm one and the sensor is  a OPT-101. The first picture shows the transmitter and the optical sensor head. The second picture shows the grey tube that contains the lens and the optical sensor. In the background you can see the small red light that comes from the LED.
DL2CH transmitter and optical sensor

DL2CH transmitter and optical sensor

Testing optical communication ...

Testing optical communication ...