This guide will help create more focused IQ recordings @300Kbps wide rather than at 2.4Mbps.
This has the benefit of smaller files or longer recordings.
Install the SDR# plug-in "IFRecorder" [SDRSharp.IFRecorder.dll]
- Download from here
- This install requires copying 2 .DDL files to your SDR# folder.
- Add MagicLine to "Plugins.xml" using Notepad (see 'MagicLine' below)
Code: Select all
<add key="IFRecorder" value="SDRSharp.IFRecorder.IFRecorderPlugin,SDRSharp.IFRecorder" />
Start SDR# as normal
Tune to frequency (Make sure this frequency is centered in spectrum display) Use >|<
to right of tuning frequency.
In SDR# set to WFM and Bandwidth to 30,000
Make sure all settings are what is used for normal TETRA operation. (But use above values)
On sidebar of SDR# there is a tab called 'IF Recorder *'
- Select '16 Bit PCM IQ'
- Select "Folder select" for file save location.
- Click 'Record'
Look at 'Write' (= File Size') in panel to monitor this size.
Capture PDUs of interest, Try and get a few. Keep size no bigger than 300MB.
If PDUs are sent infrequently, don't create a 300mb file with one event in it.
D_SDS_Data PDUs of interest:
- Protocol:Location_information SubType:Immediate_location_report_request
- Protocol:Location_information SubType:Long_location_report
This recorded file is saved in your set "Folder select" folder under "IF" folder.(e.g. 22-31-06_435112kHz.wav)
Do not rename file as it is important in proper playback with SDR#.
Use ZIP to compress WAV file to smaller size. (7zip is best and can halve file size, but is slower to compress)
Upload file to online file host.
Trimming of IQ recordings is possible using a free audio editor called Audacity
Using SDR# WAVPlayer plug-in
It is possible to find events on the timeline. Make note of the times and use below.
This is handy if you have a big file and only a few events in it. (Don't send me massive files with 1 or 2 events. Trim them)
Install then run Audacity
Drag and Drop the IQ file recorded with "IFRecorder" in to Audacity.
You will probably get a warning about import method. Choose "Read the files directly from the original" (faster).
The file should load with the correct SampleRate and bit depth. "300000" and "32-bit float"
Project Rate (Hz) on bottom left corner must be same as SampleRate (300000)
On the waveform window find the time and highlight with mouse. Click and drag.
Have a lead-in and lead-out of about 10 seconds from event.
With event highlighted select from menu File > Export Selection...
Use same file name (don't modify)
Save to different folder than original (Don't overwrite original)
add metadata. Click OK
Done. Repeat as required.
Any questions let me know.
Hi Alessandro, the more IQ samples you can provide the better.
Any of the PDUs listed above would be good, but mainly "Protocol:Location_information SubType:Long_location_report"