- Jared May 24, 2015 at 4:08 pm
VSG + BB60C looks pretty swish!
Is there a reason when I select RF on/off I get a nice transition, yet when I have modulation on, the same cycling of RF on/off produces a CW peak noticably off-freq, a CW peak on-freq, then the modulated RF?
Perhaps you need to re-arrange the sequencing such that the LO or whatever is on-freq, and you turn RF on.
Really want to see the ISM (FSK etc) demodulation as this is particularly relevant for me.
BB60C is very fussy about having a direct to host connection (w/ Spike 3.0.8)
JaredJared May 24, 2015 at 6:01 pm
A burst transmission mode button – transmits ‘n’ packets?Andrew May 25, 2015 at 3:58 pm
I can’t comment on the mod on/off note. Will get Justin to reply when we get back to the shop.
I can say FSK is on our roadmap. No timeframe yet, but very much something we want to do.
What kind of connection difficulties are you experiencing?
A.J.Jared May 26, 2015 at 6:52 pm
The connection difficulties occurred quite often when running through a USB3 hub (thinkpad dock-like thingy) even with both connectors plugged in. This went away when I moved it to the laptop-side USB3 ports.
With the BB60C taking up two ports I’m running out!
JaredAndrew May 26, 2015 at 7:55 pm
The only thing we have found to be consistent is direct connection to a PC with native (hardware on cpu) USB 3.0. We have had some luck with USB 3.0 hubs and PCI USB 3.0 cards, while others outright fail. I can’t comment on the Thinkpad hub unfortunately.
I asked Justin about the behavior you noted with the mod on/off button, and this appears to be the necessary setup when using the DDS on the VSG. You will see this on the frequency modulated signals such as FM/FSK. You will see another type of behavior for the ARB modulated signals like PSK/multi-tone, again, simply the necessary setup. We are assuming you are looking to achieve some sort of video trigger effect, especially with the request to transmit ‘n’ packets. This is definitely something we will consider on the next hardware revision if we can.
As always, I keep track of all feature requests, thank you for testing the VSG.
A.J.Jared May 26, 2015 at 8:49 pm
I’ll have a look to see what it does in the other modulation modes.
I guess the ability or inability to do clean burst and transitions depend on how youve done the hardware implementation (i.e. antenna switch, PA input switch/enable…)
I’m after a burst (n-packets) so we can simulate the ISM performance which is duty-cycle limited to 0.1% in our application.
A clean first RF isnt critical for us, but probably something you should address long term.
We had all manner of problems with our ISM links in the office a day or so ago… (I’d lifted the in-band noise floor CONSIDERABLY by forgetting to turn off the RF O/P)Jared May 26, 2015 at 8:50 pm
Also, is there a plan at any point to limit the bandwidth so the BB60C will run on USB2.0?
Andrew May 27, 2015 at 8:39 am
- This reply was modified 8 years, 6 months ago by Andrew.
Thank you for clarifying your needs on the burst transmit. Currently the ARB functionality allows you to set a period value of up to 64k (pattern memory of 2k I/Q) which depending on pattern length can get you close to the duty cycle you need. This is only exposed through loading a custom ARB file though, so I think we would need to expose the period setting through the software/standard mods at some point to be truly useful.
At this point, the BB60C is only going to run on USB 3.0. The architecture is such that it requires a host PC to perform the majority of processing. The device itself has little resources to do the processing required to turn IF samples into sweeps (FFTs), or decimate, and this is what is needed to reduce throughput to the PC. Look for future products to address this.
A side note, the USB 3.0 hubs we use in shop are these http://www.amazon.com/Belkin-SuperSpeed-USB-4-Port-F4U058tt/dp/B009AR2MD2. They let us connect and run up to 8 BB60Cs at a time off a standard laptop.
A.J.Justin Crooks May 27, 2015 at 11:52 am
We could create a “packet” mode: send 2 – 508 symbols, then “off” for up to 65,000 symbols. Would this satisfy your requirement?Justin Crooks May 27, 2015 at 12:07 pm
AJ pretty much summed up what you see. The center frequency gets set, then the frequency modulator (which offsets the center frequency) gets activated, then the modulation pattern begins looping.
I am looking at adding packet-based digital modulation with a 2-508 symbol packet followed by an “off” period of up to 65,000 symbols. This could easily give you a 1% duty cycle. Let me know if you are interested. The only (minor) challenge is I would have to convert FSK math from frequency modulation to its quadrature amplitude equivalent to enable this.Jared May 27, 2015 at 3:55 pm
Thanks for your replies!
The packet based method might work for us…
Thanks for the explanation around USB3. I didnt get a BB60C for home because none of my home machines have USB3! It made the justification to the other half untenable trying to get both a BB60C AND a new machine!
@work I have a USB3 laptop so no issues here.HerbertN January 5, 2016 at 9:08 pm
I am having some trouble obtaining a valid device number (in LabVIEW) when I use either “sgStatus sgOpenDevice(int *device) “ or “sgStatus sgOpenDeviceBySerial(int *device, int serialNumber)”. sgStatus appears to come back with a valid response, i.e. no error is indicated.
I do get a valid response when I use “sgStatus sgGetDeviceList(int deviceList, int *length)” in my LV implementation, i.e. I get the device serial number. This shows I am interfacing to the DLL correctly. When the opening of the device fails, the function “sgStatus sgGetDeviceList(int deviceList, int *length)” then returns a -1 for the Serial Number of the device. When in this state I have to shut down LV and unplug the VSG25A to get back to normal operation.
Details of my environment are below –
1. Windows 7
2. VSG25 Software V1.02
3. LabVIEW 2013.
I have attached a capture of the USB port traffic, for when I do an open the device by SN in LabVIEW in the hope that this elucidates the issue further.
Any suggestions would help me get over this road block and would be appreciated.
HerbertHerbertN January 5, 2016 at 9:11 pm
Ok, try that file upload again.
Attachments:You must be logged in to view attached files.Justin Crooks January 6, 2016 at 8:53 am
Thank you for reporting this. I will take a look at this in a few days and see if I can duplicate the problem. Labview places several restrictions on what a DLL can and can’t do. There may be an incompatibility we need to address.HerbertN January 6, 2016 at 2:06 pm
ok thank you. Let me know if there is more info you need.HerbertN January 6, 2016 at 4:27 pm
for the function sgSetPSK, are the translations for the types as shown in the attached file? Are they passed as unsigned 8’s?
Attachments:You must be logged in to view attached files.Justin Crooks January 6, 2016 at 5:29 pm
sgModulationType is an enum, generally equivalent to an “int”. If you cannot include the header file with the enum (e.g. LabView), you can just use an int.HerbertN January 6, 2016 at 5:37 pm
Ok thanks. I had forgot there was a header file for the dll. Out of practice! LabVIEW spoils you!
HerbertHerbertN January 12, 2016 at 4:01 pm
I was wondering how this issue is coming along?
HerbertJustin Crooks January 13, 2016 at 2:55 pm
I made a LabView program that opened, set frequency, amplitude, CW mode, waited 3 seconds, then closed the device. The only time I ran into a problem was when I did not close the device before trying to run it. If the device does not close, then when you try to open it, it will give you error -4.
Here it is. Maybe it will help?
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