Hello magintd,

The IQ samples are stored in the binary file as 16 bit signed integers, interleaved (I1, Q1, I2, Q2 … etc). The 16 bit integers are scaled to +/- 32767 with an additional scaleFactor to bring them into the 0-1 range.

The proper way to recover the IQ values are
float floatReal = ((float)int16Real / 32767.0) * (1.0 / scalefactor);
float floatImag = ((float)int16Imag / 32767.0) * (1.0 / scalefactor);

Where the scaleFactor is found in the XML file.

Let me know if you have additional questions.

Regards,
A.J.

Hello sajdenman,

The audio demod mode does have a limiting bandwidth of about 300kHz.

You could manually measure your frequency deviation in zero-span mode using the FM plot and markers to measure the peaks and troughs. I don’t know if this would be sufficient for you.

Let me know if you have additional questions.

Regards,
A.J.

Hello Claudio,

Thank you for posting your findings here. I have also received your email with this document.

Have you tried a resolution of 1080p yet? I have yet to be able to reproduce these issues at 1080p. I’m wondering if this is another graphical issue at the 4K display resolution.

Regards,
A.J.

Hello magintd,

I can clarify. The bbr file is a flat recording of sweeps only (frequency domain ‘bins’). The IQ data is not recorded in this file. The sweeps are stored as min/max arrays. If the avg detector is enabled, min/max should equal the same values. I will attach a basic bbr parser so you can see the layout and how we parse the files in our software.

If you are looking to get IQ data, then we do have another recording feature in zero-span that records IQ data. If you are looking for the ultimate flexibility, you could grab IQ data directly from the device with our APIs.

Let me know if you have additional questions.

Regards,
A.J.

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Hi Fabrice,

Thank you very much for the feedback. I like all of your ideas! We will definitely take these ideas into consideration as we further develop our software. Thank you again.

Regards,
A.J.

Hello Fabrice,

Currently the software limits the zero-span acquisition to ~4M points. We do not currently have plans to increase the number, but there is another way you could achieve a longer sweep time. There are record/playback control panels located along the bottom of the application in zero-span mode. You could set up a 30+ second recording and then play that back in the software. Playing back the recording is very convenient as you can scroll through the IQ data and control playback rates. Even with playback through, it will still only allow you to plot 4M points at once.

I hope this helps, let me know if you have follow up questions.

Regards,
A.J.

Hi Joe,

Thanks for sharing the video with us. It was a fun watch. Those were some neat Labview projects. I’ve been meaning to learn it. Good stuff.

Regards,
A.J.

You can use either function. They both serve the same purpose, the bbGetIQ function just has additional flexibility in how much data you acquire, keeping track of data loss, data left in the queue, and control over flushing the IQ data queue. Admittedly the bbFetchRaw function is much simpler and may be easier to use in Labview.

Regards

Hi Joe,

Did you get download the latest API files from the link I posted above? The bbFetchRaw function is deprecated and is not used in any of the examples I provide. The function that replaces it is the bbGetIQ function and has more flexibility.

That said, decimation is the only way to control the sample rate of the device. bbFetchRaw will always return the same amount of data per call. You do not need to call bbQueryStreamInfo more than once. bbGetIQ allows you to retrieve an arbitrary amount of samples per function call. bbFetchRaw guarantees no loss of samples assuming data retrieval keeps up with the sample rate of the device. The API will store about 3/4 of a second worth of data before data loss occurs.

This information and more can be found in the API manual at
https://signalhound.com/sigdownloads/BB60C/BB60-API-Manual.pdf

Regards,
A.J.

Hi Joe,

Glad you found your problem with that function.

Regarding getting IQ data from the receiver, take a look in the examples folder. There will be an example of the minimal IQ acquisition setup. This should be a good starting point. If you don’t see the examples folder, get the latest API files from this download

https://signalhound.com/download/bbsa-application-programming-interface-for-windows-3264-bit/

Video triggering occurs in the Spike software. The implementation is simply looking for the transition across a certain amplitude. (for() loop through each IQ sample). Pattern triggering is much more involved and is performed in the Spike software as well.

Regards,
A.J.

Hi Joe,

Yes, this call should be functional. Spike uses this function to properly determine which device is connected to the PC. You are free to email me any example you have where you find the function not behaving as you expect. I can take a look and see if I can reproduce it.

Regards,
A.J.

Hello Claudio,

If you are able, send me some pictures of the graphical issues you are seeing in Spike. You can email me at aj@signalhound.com. I will see if there is anything I can do to help. Also, if you have any pictures or descriptions of the zero-span issues you are having at 1MHz, include those too. I look forward to your email.

I am glad you were able to get HDSDR working.

Regards,
A.J.

Hello ssw,

Did you download the API files found at this link?
https://signalhound.com/download/bbsa-application-programming-interface-for-windows-3264-bit/

In this download folder you will find two examples, simple_sweep_1 and simple_sweep_2. They will show you how to open, configure, and acquire data from the SA44B. You will use the saConfigCenterSpan function to control the frequency range of a sweep, and you will use the saGetSweep functions to acquire one sweep at your desired configuration. The example files should be able to be compiled and ran.

Hopefully this is enough to get you started. Contact us at support@signalhound.com if you have additional questions.

Regards,
A.J.

Hi Joe,

Thanks for the feedback. I’m currently working on a scroll bar for the symbols and a video trigger delay, which delays the measurement ‘n’ symbols after a video trigger is seen. I believe both of these will benefit your use case. Expect these next release.

Regards,
A.J.

The 2FSK measurements are definitely geared more towards GFSK/GMSK signals with a 0.5 modulation index.

The signal looks like an unfiltered FSK signal with 12kHz deviation and 1.2baud? Our FSK demodulation expect a deviation which is a fraction of the overall symbol rate. For example, at 1.2k baud, the maximum deviation our software could handle is ~1.2kHz. Our algorithms work at an oversample rate of 16 which is going to limit the bandwidth of your signal.

Your best options working within the limitations of our software, would be to use zero-span to visualize the data in the FM plot, or select a sample rate in the demod mode that is much higher (as you did with 50kHz) and work around the repetitive symbols.

A.J.

Hi Joe,

Currently there is no way to configure the software as you described. I think these are very good ideas, and is something we might be able to implement in future software releases.

Regards,
A.J.

Thanks for the update Joe. I apologize that you are still experiencing these ‘glitches’.

Did we ever collect the model number of the newer PC? It would be useful for us to have this information. Looking through my emails I see specs of the PC but not a specific model number.

Hello Joe,

Are you using the digital demodulation measurements in the Spike software or zero span? I am attaching a quick image I took of the software configured for the settings you listed. This might help you configure the software for 2fsk demodulation.

The device decimation is selected based off of the chosen symbol rate. We do allow the user to customize the IF bandwidth a bit, but not enough to change the decimation of the receiver.

Let me know if you have additional questions.

Regards,
A.J.

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Hello Lee,

If you have additional questions, you may email justin @ signalhound dot com. The previous response from Justin described how you would use an external trigger and 10MHz reference to phase correlate two streaming receivers. If you need dual channel phase locked receivers without going through this much effort there are several receivers on the market which can do this for you. If you have more specific questions about your application, it would be helpful to know more about your setup and what you have accomplished so far. We look forward to your email.

Regards,
A.J.

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