How to get MaxHold spectrum data from RSA306B with RSA_API?

Posted Mon, 08 May 2023 13:35:43 GMT by Kobierski, Marianne

I am trying to collect spectrum data from an RSA306B. Using the signalvu program the data trace looks good: clear shape and max values around -30 dBm. How do I get this data trace via the RSA_API though? I tried two approaches without success: <ol> <li>Using "SPECTRUM" commands - there doesn't seem to be a way to set maxhold on.</li> <li>Using "DPX" commands - data is the right shape but wrong values.</li> </ol>

Posted Mon, 08 May 2023 13:40:17 GMT by Kobierski, Marianne

Attachments: Figure of nice signalvu trace, figure of "SPECTRUM" command data (without maxhold and with trying to set maxhold using the dpx command for it*), figure of "DPX" command data (right shape wrong values). * Added this line to the end of the config_spectrum function as it seems to be the only way to set maxhold on. Didn't seem to have any effect.: <pre style="background-color:#2b2b2b;color:#a9b7c6;font-family:'JetBrains Mono',monospace;font-size:9.8pt;">rsa.DPX_SetSpectrumTraceType(RSA_API.SpectrumTraces.SpectrumTrace1, RSA_API.TraceType.TraceTypeMaxHold) </pre>

rsa_api - dpx settings.png (430.3 KB) rsa_api - spectrum settings.png (395.1 KB) signalvu - expected trace.png (304.0 KB)

Posted Mon, 08 May 2023 13:45:58 GMT by Kobierski, Marianne

Here is the code for the "SPECTRUM" commands approach: theDll = ctypes.util.find_library("C:\\Tektronix\\RSA_API\\lib\\x64\\RSA_API.dll") rsa = ctypes.cdll.LoadLibrary(theDll) search_connect(rsa) specSet = config_spectrum(rsa) trace = acquire_spectrum(rsa, specSet, measurement_time) freq = create_frequency_array(specSet) def config_spectrum(rsa, center_frequency=15e6, reference_level=-20, frequency_span=30e6, res_bandwidth=10e3):     rsa.SPECTRUM_SetEnable(c_bool(True)) rsa.CONFIG_SetCenterFreq(c_double(center_frequency))     rsa.CONFIG_SetReferenceLevel(c_double(reference_level)) rsa.SPECTRUM_SetDefault()     specSet = RSA_API.Spectrum_Settings()     rsa.SPECTRUM_GetSettings(byref(specSet)) specSet.window = RSA_API.SpectrumWindows.SpectrumWindow_Kaiser     specSet.verticalUnit = RSA_API.SpectrumVerticalUnits.SpectrumVerticalUnit_dBm     specSet.span = frequency_span     specSet.rbw = res_bandwidth rsa.SPECTRUM_SetSettings(specSet)     rsa.SPECTRUM_GetSettings(byref(specSet))     rsa.SPECTRUM_SetTraceType(RSA_API.SpectrumTraces.SpectrumTrace1, True, RSA_API.SpectrumDetectors.SpectrumDetector_PosPeak) def acquire_spectrum(rsa, specSet, measurement_time):     ready = c_bool(False)     traceArray = c_float * specSet.traceLength     traceData = traceArray()     outTracePoints = c_int(0)     traceSelector = RSA_API.SpectrumTraces.SpectrumTrace1 rsa.DEVICE_Run()     time.sleep(measurement_time)     rsa.SPECTRUM_AcquireTrace()     while not ready.value:         rsa.SPECTRUM_WaitForDataReady(c_int(100), byref(ready))     rsa.SPECTRUM_GetTrace(traceSelector, specSet.traceLength, byref(traceData),                           byref(outTracePoints))     rsa.DEVICE_Stop()     return np.array(traceData) And here is the code for the "DPX" approach: freq = config_DPX(rsa) fb = acquire_dpx_frame(rsa, measurement_time) trace = extract_dpx_spectrum(fb) def config_DPX(rsa, center_frequency=15e6, reference_level=-20, frequency_span=30e6, res_bandwidth=10e3):     """     <a href="https://forum.tek.com/viewtopic.php?f=588&t=139112">https://forum.tek.com/viewtopic.php?f=588&t=139112</a>     """     yTop = reference_level     yBottom = yTop - 100     yUnit = RSA_API.VerticalUnitType.VerticalUnit_dBm dpxSet = RSA_API.DPX_SettingStruct()     rsa.CONFIG_SetCenterFreq(c_double(center_frequency))     rsa.CONFIG_SetReferenceLevel(c_double(reference_level)) rsa.DPX_SetEnable(c_bool(True))     rsa.DPX_SetParameters(c_double(frequency_span), c_double(res_bandwidth), c_int(801), c_int(1),                           yUnit, c_double(yTop), c_double(yBottom), c_bool(False),                           c_double(1.0), c_bool(False))     rsa.DPX_SetSogramParameters(c_double(1e-3), c_double(1e-3),                                 c_double(reference_level), c_double(reference_level - 100))     rsa.DPX_Configure(c_bool(True), c_bool(True)) rsa.DPX_SetSpectrumTraceType(RSA_API.SpectrumTraces.SpectrumTrace1, RSA_API.TraceType.TraceTypeMaxHold) rsa.DPX_GetSettings(byref(dpxSet))     dpxFreq = np.linspace((center_frequency - frequency_span / 2), (center_frequency + frequency_span / 2), dpxSet.bitmapWidth)     return dpxFreq def acquire_dpx_frame(rsa, measurement_time):     frameAvailable = c_bool(False)     ready = c_bool(False)     fb = RSA_API.DPX_FrameBuffer() rsa.DEVICE_Run()     rsa.DPX_Reset()     time.sleep(measurement_time) while not frameAvailable.value:         rsa.DPX_IsFrameBufferAvailable(byref(frameAvailable))         while not ready.value:             rsa.DPX_WaitForDataReady(c_int(100), byref(ready))     rsa.DPX_GetFrameBuffer(byref(fb))     rsa.DPX_FinishFrameBuffer()     rsa.DEVICE_Stop()     return fb def extract_dpx_spectrum(fb):     # When converting a ctypes pointer to a numpy array, we need to     # explicitly specify its length to dereference it correctly     dpxBitmap = np.array(fb.spectrumBitmap[:fb.spectrumBitmapSize]) # Grab trace data and convert from W to dBm     # <a href="http://www.rapidtables.com/convert/power/Watt_to_dBm.htm">http://www.rapidtables.com/convert/power/Watt_to_dBm.htm</a>     # Note: fb.spectrumTraces is a pointer to a pointer, so we need to     # go through an additional dereferencing step     raw_trace = np.array(fb.spectrumTraces[0][:fb.spectrumTraceLength])  # 0 indicates trace 1     trace = 10 * np.log10(1000 * raw_trace) + 30     return trace

Posted Tue, 09 May 2023 23:31:53 GMT by Teles, Afonso

Hi Marianne, The RSA API gives you direct access to the samples from the RSA ADC, it requires significant post-processing work to then transform that into a dBm measurement. Additionally, the RSA API is unsupported and only meant for very specific cases where it's needed (Linux platforms or high transfer rate applications). Instead I would suggest you use the SignalVu-PC programming interface: <a href="https://www.tek.com/en/manual/spectrum-analyzer/signalvu-pc-vector-signal-analysis-software-programmer-manual-rsa306">https://www.tek.com/en/manual/spectrum-analyzer/signalvu-pc-vector-signal-analysis-software-programmer-manual-rsa306</a> This interface allows you to get the spectrum trace with just one SCPI command, with all the processing being handled by the SignalVu-PC application.