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Sadak,
Yes, the resolution bandwidth, or RBW, is essentially the resolution of your frequency readout. For exact frequencies we have two tools: the frequency difference meter, and the modulation analyzer in zero span.If you are looking for precise numeric calculations on an exact frequency, I would encourage you to use our API to acquire I/Q data, which can be processed to provide whatever measurements you desire.
For spans (not RBW) of 200 kHz or less, the LO frequencies are RF + 10.694 MHz and RF + 2.921 MHz. For spans greater than 200 kHz (up to several GHz), the LO frequencies are RF + 10.7 and RF – 10.7. In both cases the signal is sampled twice.
The 2.9 MHz IF is used when span is 200 kHz or less, to provide superior image rejection for narrow-band sweeps. It sweeps once with a 10.7 MHz IF, and once with a 2.9 MHz IF, and compares results to provide the cleanest spectrum possible.
Ivan,
That formula is quite accurate for flat top windows, but may be a fraction of a dB off for nutall and gaussian, due to the RBW shape.Wizardek,
The IF frequency for the SA44B in fast sweep is 10.7 MHz. Image rejection works by injecting the LO low side (RF – 10.7 MHz), and then high side (RF + 10.7 MHz), and taking the lower reading for each bin.Oh, sorry, I missed the bit about Windows XP. No, Spike (all versions) is only compatible with Windows 7 / 8 / 10. Our legacy software will work on XP.
Ramos,
Yes. Spike is compatible with all of our spectrum analyzer and tracking generator products. Some models may require a firmware upgrade, but this only affects a few percent of units.JoeQSmith,
This is a very unusual problem. We will do what we can to help you via email. Trying a second computer is an excellent troubleshooting step. If the problem is limited to the Asus, we may be able to dig a little deeper. If not, we may just want to set up an RMA for warranty repair or replacement. Keep us posted.Occasionally we get sticky USB problems when something goes wrong during a device’s initial configuration. To remedy this, you sometimes have to remove the instance of the USB device. This tool: http://www.ftdichip.com/Support/Utilities/CDMUninstaller_v1.4.zip
can be used to remove all memory of previously connected Signal Hounds.
Launch the GUI version, leave teh VID at 0403, change the PID to 6010, click “Add”, and then click “remove devices”. Then re-install the USB driver, connect your device, wait for the “searching for updated driver” to finish (1-2 minutes sometimes), and then launch Spike.Interesting. It is probably safe to ignore the first overflow flag after a settings change from an overflow condition. Subsequent overflow flags should be treated as valid.
JoeQSmith,
We do not have any provisions for locking the time base to an external source. There is a 24 MHz time base that could have been locked with an additional timebase PLL, but that would only get you within a few Hz, not a true lock, due to the resolution of the RF PLL.
Any future vector signal generators we produce will have the ability to lock, but they will be significantly more expensive.Andrew,
The ADC overflow flag is only cleared immediately after reporting it. When you are doing single sweep, with an overflow condition (e.g. gain 2 atten 0), it reports the overflow, clears the flag, and then immediately sets the flag again (overflow condition still present). You set the attenuator to 10 dB (no more overflow), sweep, and it reports there was an overflow condition since the last time it was reported. But the next sweep reports no overflow.
This is the expected behavior. If this is not what you are seeing, let me know.Because of the architecture limitations of the SA44B, it really is not a good fit for EMI precompliance. The SA44B is not capable of picking up some types of transient signals without disabling image rejection, and for EMC precompliance, you want a high degree of confidence for all types of signals that the SA-series really can’t provide.
Ivan,
High Q devices require a long settling time, often tens of milliseconds, before an accurate measurement can be taken. This is one reason we limit the step to 1 kHz–any finer resolution would take exponentially longer to measure.
In Spike, you can accomplish a high Q insertion loss measurement using a MAX HOLD trace and the TG CW utility, manually stepping across the frequencies of interest. Your “external” sweep with max hold is a good approach to this, and essentially automates this process.
For this type of measurement, “zero span” would be the best place. Just set your IF bandwidth to your channel bandwidth, with the signal centered.
If it is a constant amplitude envelope (e.g. FSK, GMSK), a marker anywhere gives you channel power. If not, you could export the zero span data into a CSV, and then (in mW units, not dBm) average the power of each sample within your packet.
I’ll talk to AJ and see if this is something we could add to the next release.
Users never used to have to uncheck the VCP in the advanced driver settings, but we are seeing that more and more now. I’m glad you got it fixed.
For others who have this problem, in the device manager, locate “serial converter A”. On the Advanced tab, uncheck “load VCP driver”. Then do the same for Serial Converter B.
For the TG44A, repeat this for “serial converter” (no A or B)
It is an AD9864. We run it at 10.7 MHz, or bypass the mixer and run it at 2.9 MHz in “hung mixer” mode.
http://www.analog.com/media/en/technical-documentation/data-sheets/AD9864.pdfIf you are referring to frequency vs. time plot or data, you can use our zero span mode for short captures, or our API for continuous I/Q data, which you can FM demodulate using the atan2 function.
It’s actually a sigma delta 24 bit ADC, digitally converted to 16-bit I&Q.
It’d be kind of cool to see a vertical bar representing channel power on the spectrum plot, and then you could show the video trigger threshold on that. Just throwin’ out ideas…