Reflections about a remote mediumwave listeners station

It should be more correct, the system was not running anymore, so it was changed.

The disaster with the Trekstor tablet since November has now come to an end. Even after the second inspection of the device - shortly after it came back from the 1st - at Trekstor no error could be found. My subsequent in-house inspection revealed that the battery is no longer providing enough power to power the SDR and WiFi adapters. Unfortunately, the battery is excluded from the warranty, permanently installed and obviously not available as a spare part. Even an external current hub is no longer useful.

The device is still functional and useful for other purposes, but unsuitable for the remote station. The dream of a functioning station based on low power consumption has to be redesigned. The solar-powered 12 V DX system needs a new heart.

About the progress of my efforts to build a small but nice station in the garden, I will continue to report when I have found and tested appropriate devices.

Maybe I'll get new ideas and suggestions at Ham Radio.

Until then, the break screen remains here.

I wish all of you reading this a great time - and maybe you'll see each other in Friedrichshafen!

73, Willi

Meanwhile, it has become the beginning of March, and for a long time nothing has happened here in the blog. The trigger was the broken tablet, which was sent for repair at the end of November 2017, and did not return until mid-February 2018. It had disappeared

After the space on the tablet was too low I had to make a decision: the thing must be "cleaned", or put on again. The "cleaning process" ended in a disaster. The operating system WIN 10 did not start anymore. After 2 days of futile measures I found the crucial file over the Trekstor service. After another day of downloading 4.5 GB of data, the system could be restored. Another day went on for testing. The update brought some innovations, which did not make the "fish box" Windows better. However, updates to the SDR console promise to improve performance. The station is now running with version 3 and can resume operation in the coming days under my Argus eyes.

Update (1) from Argus eyes: v3 beta of SDR Console is not suitable to run here for now. So v2.3 is still the best.
Update (2) from Argus eyes: The tablet does not recognise USB devices. Prob. a accu issue. I am in contact with Trekstor about this issue.
Update (3) from Argus eyes: Tablet was sent to Trekstor. Dx is not really possible right now.

After long experimental sessions with the tablet I discovered more good reasons to use the tablet in my remote station. The background why I did long tests is the circumstance I can only use 12 V solar power and need a low Ah consumption gear.

As I mentioned the other day listening and recording with the ELAD FDM-SW2 software was only possible with a limited bandwidht set to ~192 kc/346 kc, which is beyond my needs. The ELAD FDM-SW2 software consumes more resources than the tablet could provide. Recordings stuttered. Now I was testing the Studio 1 software and was able to record and listen stutterfree with ~1500 kc bandwidht. This is enough to record the whole MW Band e.g.

So my complaints are now going to the software developers. Studio 1 is fine, lets say very fine, but not able to record automatically at a certain time, ELAD FDM-SW2 does but is not able to record ~1500 kc bandwidht.

Another issue with the tablet is that it connects only through USB2 (and not USB 3) with the ext. HD. At some times the audio hangs for 1-3 sec. which does not affect the recording in most of the cases, but in some. The tablet can use a 128 GB microSDXC-Card which could be much more faster. I did not test this now because I need more than 128 GB of space.

As I wrote the other day recordings and listening through the HD are possible if connected through a USB-Y-Cable to a seperate batterie charger. The Trekstor Surftab is not so bad as thought here. It is suitable to run the station.

Before reading this: you have read all articles in this blog about this tablet?

Listening with the Trekstor and ELAD-SW2-Software is fine if you accept the bandwidht limitation of 192 kHz. There are two things you have to know.

(1) With a connected FDM-S2 the power consumption is high. After 2 hours or so the tablet will shut down if the FDM-S2 is not connected to a seperate power supply. All works fine with this seperate connection and is durable.

(2) Recordings with a separate HD are not possible. The recordings will stutter. So the only chance to record something is with the tablet itself is on the inbuilt disc or on microSDHC-card.

After testing and testing the Trekstor under different problematic situations, I came to the conclusion that this tablet is not suitable to run durable as a remote station. The other day I wrote about problems with the HDD. They are solved. The irregularity was a somehow wrong USB-Y-Cable. After attaching another one the HDD runs smooth. The other issue is the small bandwidth. The tablet resp. the ELAD Software stutters if the bandwidth is not set to 153,6 kHz. That's too less for longtime operations and recordings. I have no idea if this issue can be solved. The tablet comes with 1GB RAM, has a 1.33 MHz processor and there is only 1,3 MB free space left on a disc that comes with 16 GB. Much of it is covered by the operating system. I don't run a lot of additional software. As I wrote in a futher article about 1228,8 kHz bandwidth I cannot confirm this anymore, the devil knows why I came to this result. Only 153,6 kHz bandwidth is left now! The issue might come from the power supply with the SAVAKE USB-cable. If no charging is running in the background the bandwidth could be set to 614.4 kHz. But recordings may be disturbed by lite stutters, as you can hear during listening. If you switch the SAVAKE cable to charging it is possible to record with 614,4 kHz bandwidh for a while until stuttering begins again. The same with 307,2 kHz. If the ELAD FDM-S2 is connected directly as a single device with a single cable to the only USB port 614,4 kHz is possible. And yes 1228,8 kHz sometimes too. It's irregulare.

As I wrote previously, additional steps were necessary. Restarting the system was sufficient to determine that everything can run smoothly. FDM-SW2 CPU use now was 15%, total CPU usage at 23%. The data aquisition frequency of the software was set to 1536 kHz, the bandwidth of the recording is at 1228 kHz. This is the maximum amount of bandwidth to record stuttering free. After rebooting also Audioengine D1 was detected. The driver must be set in the FDM SW2 settings previously. Sometimes a restart of the software is required.

Overall, a good image. Little does what it should, but has due to its size limitations in regard to convenience. Since it is used only as a recorder, the restrictions appear first low. More remains to be seen in the continuous operation.

- CPU usage 11% -15%

- Total CPU usage 30%

- Audio quality: medium. Can be enhanced by a ext. audio amplifier, audioengine D1 e.g., which is actually not working on a hub w/out ext. power.