FM – DAB+: my logblog!

World of DX-ing

February 28 2020 – QIRX 3.2.2 released

Posted on by FMDABDXer

What’s new?

  • RSPdx is now supported.
  • DAB Fine Frequency correction: It has been improved to be now accurate to better than 1Hz in the RSP’s, and about 7Hz in the RTL-SDR dongles.
  • TII high resolution spectra: These are now showing the carrier pairs with a very good stability.
  • TII and CIR: An algorithm has been added to associate TII Id’s with their corresponding CIR peaks.
  • EPG improved.
  • Multi EPG services.
  • Constellation: An I/Q data spectrum can be selected.
  • TII recordings: The bearings angle from the receiver to the station is now included in the TII logging file.

More details can be found here. Download (and more info) here.

QIRX 3.2.2

The default Viterbi.dll included in the QIRX 3.2.2 installer is not optimized to give better SymbolTime as explained in the QIRX download page.
You can find the improved Viterbi.dll on Github. The download zip is on the right hand side of this page.
Do check out which instructions set your cpu uses. My i7 supports SSE4.1, SSE4.2 and AVX2. It does not support AVX512.
The SymbolTime can be found in the QIRX main screen.

SymbolTime ms

Changing the Viterbi.dll made quite a difference in lowering the SymbolTime on my i7 cpu.

Viterbi.dll

January 30 2022

Posted on by FMDABDXer

QT vs QIRX – RSP1A vs R820T

For DAB+ DXing QIRX and QT-DAB are great software, while RSP1A and RTL-SDR R820T are excellent hardware. The software is free thanks to excellent work from Clem Schmidt and Jan Van Katwijk.
The differences between the set-ups are minimal and price-quality wise RTL-SDR R820T is a fantastic product for DAB+.

I connected my antennas to a splitter to run QIRX and QT-DAB simultaneously. On the most MUXes there was no noticeable difference. However when doing the test in rainy, windy weather with dismal lift QT-DAB4.3 + RSP1A managed to decode
12B Liège quite easily.
QIRX3.2.1 + RSP1A managed it too but with more difficulty and most of the time only partially. QT-DAB and QIRX couldn’t do it when connected to the RTL-SDR R820T. Under normal conditions the difference between the set-ups became negligible.

It’s vital to set-up bandwidth for QIRX + RTL-SDR R820T correctly to around 1700 kHz. AGC works very well in this combo. For QIRX + RSP1A do check the Gain Reduction. Its default setting is 3. The higher the number the more reduction!
In general QIRX tends to show the TII codes quicker and more extensively than QT-DAB.
QT-DAB settings need to be checked too. AGC works well. Using RSP1A again note the LNA state selector indicate the Gain Reduction. The higher the number the less Gain. Using RTL-SDR R820T with the Autogain on you should toggle the ppm.
In general strong MUXes need a lower ppm.

Do have a look at the manuals from QIRX and QT-DAB.

QIRX+RSP1A vs QT+RTL-SDR R820T

QIRX+RTL-SDR R820T vs QT+RSP1A

January 26 2022

Posted on by FMDABDXer
MHz Block UTC ITU Ensemble + Location Details Remarks km
208.06 9D 0643 D Mein NRW DAB+, Essen-Holsterhausen (nrw) 167km
190.64 7B 0701 D hr Radio, Rimberg (hes) 333km
197.65 8B 0725 D MDR THUERINGEN, Kreuzberg (Rhön) (bay) 377km
190.64 7B 0742 D hr Radio, Großer Feldberg (Taunus)/hr (hes) 277km
190.64 7B 0755 D hr Radio, Kreuzberg (Rhön) (bay) 377km
178.35 5C 0915 D DR Deutschland, Inselsberg (thü) 403km
178.35 5C 1110 D DR Deutschland, Geislingen/Oberböhringen (bwü) 450km
178.35 5C 1128 D DR Deutschland, Weimar/Großer Ettersberg (thü) 458km
211.65 10B 1131 D Oberfranken, Ochsenkopf (bay) 513km
215.072 10D UNID DAB-9C (Ensemble 8182).
Unid logged by QT 4.3 scanner.

Map