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Hi Jing,
Yes, you have to reconfigure the receiver between I/Q captures, and yes, with the BB60, there will always be a gap when switching frequencies. I would expect the gap to be in the 10’s of milliseconds.
Unfortunately there is not a way to improve this with the BB60. Our SM200/435 has an I/Q sweep list feature, which allows for preconfigured I/Q frequency/capture_len pairs to allow for very fast switching times, (120us switch times). I can provide more information on that if desired.
Andrew
No worries Ed. This is not on our immediate road map and we have no plans to add it right now. I have added it to our customer request log but I cannot make any guarantees about when we would be able to look into this.
We recently added the average power readout (on the zero-span AMvTime plot) as a query-able value via SCPI. See the ZS:Fetch command. If you can get this value to work for you, that might be sufficient. Otherwise see my prior suggestions.
Hi MMohseni,
If you download the SDK (link below) and look in the examples folder for the BB60C, you will see a folder for C# that includes a wrapper API and an example of how to use it. This example can be easily modified and extended to suit your purposes.
https://signalhound.com/software/signal-hound-software-development-kit-sdk/
Andrew
Hi Ed,
Unfortunately we have not added SCPI commands for the zero-span channel power measurements since your last messages.
You can see a full list of SCPI commands we support in the SCPI manual found in our SDK.
https://signalhound.com/software/signal-hound-software-development-kit-sdk/There are no commands other than the ones in that document.
Andrew
Unfortunately, we are not familiar with the LoRa specification and do not have any resources to help you with your task.
Sorry, it looks like I didn’t update the SCPI manual to reflect the change.
Try “FETCH:ZS? 10” for the average power.
Let me know if you run into issues or have follow up questions.
For future reference, when making channel power measurements, both ‘average’ detector must be selected, as well as ‘power’ video units. If either of these settings are not used, you will not get consistent channel power measurements.
Hi Jacks,
Unfortunately, I cannot reproduce the problem with the provided information. Would you be willing to email us at support@signalhound.com with more information about your issue? Please provide screen shots of the Spike software and descriptions of your setup and any signals you are generating/measuring. Hopefully we will be able to quickly troubleshoot and resolve your issue.
We look forward to your response.
Andrew
Good question,
Over the years, we have learned that using a single USB 3.0 type A port will generally be OK. PCs seem to supply adequate power to our device over a single cable. Places where you can see issues is with ultraportable devices like the Surface Pro line. If you only have a single USB type A cable and it does not supply adequate power, then we recommend a USB 3.0 hub that has external power.
If you only have a USB type-C port, you will need to use an external hub that performs power negotiation/use external power. A hub such as the Anker hub linked below has been reported to work with our devices. Using a direct type-C to type-A adapter usually will not work, we believe due to power issues.
https://www.amazon.com/Anker-PowerExpand-Adapter-Delivery-Ethernet/dp/B087QZVQJX
Andrew
1) When using the I/Q recorder the scale factor is not recoverable, so you will have to use the data as full scale if saving as 16-bit ints. If using the API you can store the scaling factor separately and use it to convert to dBm if needed. The reference level being used as the scale factor does not apply with the I/Q recording utility.
2) Check out the docs for more information on scaling, we use this approach for both our BB and SM line of receivers. I/Q values have a similar scale as a voltage, but need additional conversion if you want to use them as a voltage.
https://signalhound.com/sigdownloads/SDK/online_docs/bb_api/index.html#IQDataTypesAndrew
1) My guess is that 0 duration just means the event lasted for a single sweep, and 0 bandwidth means that only a single point in the sweep exceeded your threshold. Does that line up with what you are seeing?
2) Using the recorder in Spike means that you would only have to write code that parses those files and looks for events. Using the API gives you more flexibility to write files in a format that’s better for you, and also you can automate more of the recording process vs manually saving the files in Spike. It’s the same underlying data/samples in both approaches.
Our data rate is 160MB/s. Using the API you can choose whether to receive 16 or 32-bit complex values. The 16-bit are shorts, and 32-bit are floats.
Retrieving I/Q data via the API is by default continuous. If you set the purge flag to false, the I/Q data will be continuous. The API stores about 1/2 second worth of I/Q data internally, so you must not let this internal buffer “wrap/overflow/etc”, otherwise you will have a gap in samples. You must continually poll the API for the duration of time/samples you need. You can detect gaps by monitoring the sample loss parameter and the status flag returned from the bbGetIQ function. You can request arbitrarily large buffers sizes from the API if desired. If you plan on streaming for long periods of time, I suggest requesting buffer sizes around ~1/60th of a second. This is still a small enough buffer to quickly allocate and does not call into the API (which has a small amount of overhead) too many times per second.
Andrew
Hi BDick,
The limit line amplitudes you listed are in positive dBm. I suspect you meant for them to be negative? (-50, …) Right now the limit line is being drawn off the top of the screen.
Andrew
Michael,
You will have to change the algorithm slightly.
I would continue to sum everything as linear units, and then divide through by the window bandwidth which can now be calculated with the following equation.
nWindowBW = RBW / BinSize;
Where RBW is what you asked for, and bin size is the frequency spacing between the sweep bins.
This should get rid of most of the variables used to calculate nWindowBW in your above example.
In the past we used a variable bandwidth flattop window, but now we use the standard flattop window with zero-padding to achieve arbitrary RBWs. This is a more traditional approach to arbitrary RBW selection.
Andrew
Thank you for the pictures Michael. I was able to find the reason for this difference. It is a processing change that was made last year. We altered how we process sweeps for flattop RBWs with the BB60. It should not have any effect on your measurements.
Let me know if you have follow up questions.
Andrew
Michael,
I am unable to reproduce this issue. I’m assuming you are using a BB60 device?
Are you using different RBW shapes? Going between Flattop and the Nutall window would account for an factor of 2 difference. If I use your settings with a flattop window, I get 64k points, if I use a Nutall shape, I get 32k points.
Andrew
Hello Ajaykumar,
Look in our Spike software manual (linked below). In section 4.14.5, we provide a measurement walkthrough for our WLAN measurements. This should provide you with several steps for setting up the measurement for the first time. To get a nice looking constellation you will have to use our WLAN measurement mode. No other measurement mode in the software will show you a constellation of a Wifi signal.
https://signalhound.com/sigdownloads/Spike/Spike-User-Manual.pdf
Andrew
The FFT processing is done in software. There is processing time associated with each sweep and there is blind time between sweeps where events can be missed. This is a general shortcoming of swept based spectrum analysis, and if your goal to capture 100% of short duration events, measurements like real-time and I/Q streaming are required.
Andrew
Hi Jing,
The interference hunting mode is not a real-time measurement, it operates using standard sweeps. This means for short duration events like the ones you are measuring, you can miss them. Increasing the RBW can help improve sweep time.
If all of your events are within a 27MHz span, you can use our real-time measurement mode to be able to visualize all events in the frequency domain, and use our sweep recorder to capture these events. The data format for the sweep recording is different than the recorded data in interference hunting mode, but all events that have 2ms duration will be visible.
You can also record events in zero-span using the I/Q recorder in zero-span mode. You can set up a video trigger and capture a sequence of I/Q time domain files that should contain a significantly higher percentage of the events than you capture in interference hunting mode. Depending on how the pulses arrive, it may not capture 100% of them.
Another option is to use the API in I/Q streaming or real-time mode to capture data and programmatically store the events of interest.
Andrew
Thanks for the additional feedback!
Andrew