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I have a few questions, so I write a post on the forum.
Analyzer Model : USB-SA44B
RF Generator output : Appendix File(Pulse Capture.jpg)
– Frequency : 250 [kHz]
– PRP(Pulse Repetition Period) : 500 [msec]
– TBD(Tone Burst Duration): 20 [msec]1) Can I know the latency time for each section below?
PC ————— USB Communication——– SA44B
(Spike or SDK Programing Latency?) (Measurement latency?)2) Compare (A)Spike Log [dBm] / (B)Using SDK, Code [dBm]
The same results as (A) to (B) do not come out.
Please check if there is a problem with the code using the SDK.A. Spike (Windows Application) Log Record.
– Analysis Mode : Real-time
Center : 250kHz
Span: 100kHz
Ref Level : 10 dBm
RBW : 100 Hz
Acquisition : Video Unit (Power) / Detector(min/Max)Log Save.
Channel Power : Start Logging / Stop Logging
– Appendix. Realtime(Spike)B. Using SDK, I want to measure continuous values like Spike’s real-time mode.
Please review the attached code to make sure it is correct.
– Appendix. code(real-time).pngIn the attached code, the continuous dBm value is measured .
3) Please let me know if there is a better way the current measurement conditions. (device, method, Example Source guide…)
thanks.
tyang,
1) This will be difficult to measure. This number will include USB transfers, hardware acquisition speed, as well as buffering and processing latencies in the API. For certain modes like real-time, we only provide sweeps at specific intervals which means the latency for a specific event can be anything up to that interval. That being said, latencies are likely in the 16-100ms range depending on the measurement.
2) In your code I do not see a channel power measurement. Each call to saGetRealTimeFrame returns one sweep and one persistence frame (to create the persistence display). For your purposes you can ignore the frame and just focus on the sweep. You are indexing just a single value in the sweep. The channel power measurement in Spike is an integration over a portion of the sweep based on your settings. There will be additional math to calculate a channel power value on a sweep returned from the API.
We have a couple of resources that can help you get started. The equations for calculating it are in the blog post. I have also attached a file that contains some code snippets from Spike that calculate channel power. You will not be able to compile this code, but it will illustrate the operations involved and you should be able to write your own implementation using it.
https://signalhound.com/news/what-is-channel-power-and-occupied-bandwidth/
Regards,
AndrewTyang,
The BB60C or SM200 have trigger inputs. This can help overcome software latencies if your generator also outputs a trigger. I am not sure what you are trying to test with your 250 kHz burst, but if you need to know the delay through a device under test, the BB60C offers some additional capabilities.Hi Justin & Andrew,
I have a similar job to do. What I want to try is that I need to measure the feedback time of signal produced by the signal generator controlled by in-house code through the signal analyser. I give a series of bursts whose frequency is 250 kHz for 20 ms and burst period is 500 ms. Once the signal goes into the signal analyser, the power at 250 kHz is shown periodically. Basically, I want to detect the time at which the power of the signal at 250 kHz is shown after the signal is generated by the signal generator. Would it be possible to do this with the BB60C or SM200, SDK provided by signal hound, and additional code for channel power calculation?Thanks.
gkang,
If I’m understanding your problem correctly, something like the external trigger could help with your problem. If your generator can emit a trigger at the same time as the RF, you can stream I/Q data on one of our receivers and measure the time from the external trigger position to when the RF energy arrives. You can do this with both the BB60C and SM200 using the SDK. We also have external triggering in the Spike application for these two devices, so depending on how complex your setup it, you might be able to do it with Spike.
Let me know if you have follow up comments.
Regards
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