How can I ensure a smooth transition when uploading new filter shapes?
When a new filter profile is uploaded to the WaveShaper, the instrument may go through intermediate states for a short time (few to few tens of milliseconds time scale). These states could, for example, include high or low attenuation of the signal. For some applications this is not desirable.
This effect can be mitigated by using a process referred to as “partial upload”. Under this process, the new filter is split in multiple spectral sections. Sequentially uploading these sections will then build up the desired filter shape in multiple steps, thus avoiding impacting the entire spectrum at once. Depending on the sensitivity of the application and the available time to complete the full upload of the filter, the user can decide in how many slices he would like to cut the spectrum. Typically splicing the spectrum in a few slices (like for example 3 to 6) will already provide a major improvement. Recommendation is that the spectrum is sliced in a way, that all slices contain roughly a similar power level.
The partial upload is available in the Graphical User Interface (GUI) and the Application Programming Interface (API).
When using the WaveShaper App, the partial upload is available using the “Advanced” filter settings: click on the Advanced Button in the Filter Tab of the program.
In the ADVANCED section the spectral range in which the filter shall be updated can be defined using the “Window” entry. Click the “Apply” button to upload the (partial) filter shape to the WaveShaper.
For the WaveManager program, you click on the Advanced Tab of the WaveManager interface.
Select “Window” to enable partial upload of filter shapes. Click “Apply” button to upload the (partial) filter shape to the WaveShaper.
RESTful Ethernet based API
When using the RESTful Ethernet API, we recommend to run a read current profile command before uploading a new profile to the WaveShaper. To minimize undesired filter shapes (intermediate states) during the switching process this current filter profile should be modified in sections (wavelength/frequency slices) and be reloaded to the WaveShaper.
The programming sequence is as follows:
- READ CURRENT PROFILE: for example, http://<_ip_>/waveshaper/getprofile
- MODIFY DOWNLOADED PROFILE: make changes only to the frequencies that shall be updated
- UPLOAD MODIFIED PROFILE : for example, http://<_ip_>/waveshaper/loadprofile
- repeat steps 1 to 3 until final filter shape has been uploaded
DLL based API (using the USB port)
When using the DLL based API (via USB port) partial filter profiles can be uploaded using the .wsp file format. The filter will only be changed within the frequency boundaries of the .wsp file. For example, following snippet from a .wsp file only changes the filter in the frequency range from 192.950 THz to 193.050 THz. “Full transmission” will be set for this range between the Common Port and Port 1:
192.950 0 0 1
192.951 0 0 1
193.049 0 0 1
193.050 0 0 1
Frequencies outside this range will remain unchanged.