➔ Cisco DCE Adapter for P25 STUN Connection to Quantar
| 1 minute read
In order to connect a Motorola Quantar to a P25Reflector for P25 operation I had to setup a new system for testing purposes. To connect the Quantar to a Cisco router for STUN encapsulation one normally used a Cisco V.24 DCE cable with an adapter to RJ45 on the Wireline card of the Quantar ([1]).
During placing an order with Mouser Electronics I identified the 60pin LFH connector manufactured by Molex by random.
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➔ LEDs on Tait 8105 with Advanced Digital Modem
| 1 minute read
Rick N9UMJ was so kind as to send me a Tait 8105 VHF mobile radio with an Advanced Digital Modem attached for experimentation purposes. It could serve as a MMDVM high power hot spot. But as HamRadio in Friedrichshafen is due I decided to make it an APRS tracker with a homebrew SVX_Hat board mounted on a Raspberry Pi. For optical feedback of the PTT state I configured the front LEDs to reflect the PTT state.
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➔ LNB Modification for Es'hail-2 / QO-100
| 2 minute read
After receiving the Es’hail 2 satellite QO-100 with a standard LNB on an offset dish some days ago there was the need to get the RF compontents a little more stable with regarads to frequency. We used a standard LNB with PLL technique which resulted in several kHz drift during listening to SSB QSOs. During resarch I found a nice article on the BATC Wiki ([1]) which basically outlined modifying the LNB so that an external reference frequency can be used.
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➔ Image Grid from SSTV pictures
| 2 minute read
During January 2019 there were two weekends with SSTV activity from ISS. As it would be nice to have all received images in a grid I amde a little shell script to accomplish this. You just need to rename the input picture according to the numbers of the images like 01_whatsoever.png. Missing images will be replaced by a dummy saying “picture missing”. Output is a file named output.png. The script assumes that input image size is 640x496 pixels and output is hardcoded 2560x1488.
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➔ Discard HID input from CM108 device
| 2 minute read
During experimenting with USB soundcard devices based on cm108 chips I discovered that a squelch signal on the GPIO inputs of the sound chip does trigger a keyboard event as if one pressed the “volume down” key. Depending on the system configuration that can lead to your default sound card being muted. In my case I was running UniPager as DAPNET client to the pager network in combination with a self made USB sound device with GPIO-controlled PTT.
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➔ Automated Channel Switching with Motorola GM3x0
| 3 minute read
With the integration of POCSAG/DAPNET features into the MMDVM/MMDVMHost I came to think about if it would be possible to combine an MMDVM repeater/HotSpot with a DAPNET tranmitter. The advantage in Germany is that there is a single coordinated frequency for POCSAG tranmissions on UHF. 439.9875MHz is used for fixed-frequency pagers which are modified to receive on that frequency. With latest hand-programmable pagers (e.g. AlphaPoc) it would basically be possible to set them to the repeater frequency but that wouldn’t work while one is en route.
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➔ Postmortem decoding of SSTV/APRS
| 3 minute read
This years holiday I took my ICOM ID-51 for some portable activities in D-Star. Luckily there also were some announcements of SSTV acitiviy as well as school contacts from the ISS and also a weather balloon start from Minden Germany. As space was limited I had to deal with the radio and my mobile.
SSTV decoding went quite fine using the Android app Robot36. Audio was loosely coupled to the built-in microphone of the mobile.
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➔ NX-5300 Programming
| 4 minute read
It seems like Kenwood uses totally different terminology to refer to configuration items in their radio programming software. This is my memo for various options that I discovered why program&try :).
I use the radio in NXDN, P25 and DMR modes (and FM as well). Apparently the radio can only use two of the Digital Voice modes at a time. That means you can use P25+DMR or DMR+NXDN or NXDN+P25 in a codeplug but not all three.
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➔ How to identify a genuine #MMDVM_HS_Hat
| 1 minute read
Since DB9MAT an me came up with a selfmade MMDVM_HS board called the MMDVM_HS_Hat there is a number of Chinese copies out there which we belive are bad quality rip-offs. We published our sources under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 (CC-BY-NC-SA 3.0) license which explicitely forbids commercial use (unless authorized by us). Of course these Chinese copies are not authorized and thus just a clone of our work.
To help distinguish between an orginal #MMDVM_HS_Hat and a clone have a look at the two pics below.
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➔ Modification of T-962 Reflow Oven
| 2 minute read
For the latest MMDVM_HS_Hat project by me and Mathis, DB9MAT I arranged for a reflow oven model T-962 which is a good assistant for SMD soldering work. As per Toufik, F0DEI there were some interesting modifications to make in order to improve the results as well as to get rid of smelly evaporations.
There is a famous article on hackaday (See [1]). It was the reason to open up the unit and get some improvements done.
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