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DDR,
If a 30 MHz high pass filter would not affect the signals you need to produce, the VSG60A will probably work. Otherwise, you’ll need a dedicated arb / function generator instead.Unfortunately we do not support USB 2.0 speeds with the SM200B. While I can see the benefit of the convenience, the capabilities would be tremendously reduced at USB 2 transfer speeds, and it would be a very large firmware change, so we opted not to add the support at all.
Yes, we can’t stream (gap free) more than 170 MHz of bandwidth without a lot more paperwork. We can’t frequency mask trigger on more than this either. But for short captures followed by gaps, it is my understanding that the same rules don’t apply. That being said, I don’t think we will allow the filter to be disabled, but future products will probably have more filtering on the FPGA to avoid this video triggering on strong signals outside the bandwidth.
This sounds like perhaps a moving average filter before video trigger would work. We have talked about adding this feature. I’ll chat a bit with the team and see what they think.
I can speak to the signal path portion. When your sample rate exceeds 61.44 MSPS, the video trigger moves from the API to the FPGA. It triggers on the amplitude of the raw 250 MSPS data, before the digital bandpass filter is applied. There is significant rolloff beyond the 160 MHz point, but triggering can still occur. The thought was if you are video triggering on a signal contained within the 160 MHz bandwidth, it would be transparent to the user, but energy just outside the 160 MHz bandwidth is the exception.
This was resolved in the SM200C, since we filter and resample more aggressively on the FPGA and trigger on the PC, but I realize this doesn’t help you.
Hysteresis: I would love to hear more about what you had in mind, and if you can give us a use case. More advanced triggering is something we have talked about and would like to explore. Obviously there are a lot more options at the API level than the FPGA level.
We don’t have a good solution for a high dynamic range VNA. If you need to measure gain up to 75 dB (without phase information) you could use our TG + SA or BB, plus 60 dB of external attenuators.
We do not currently carry noise sources. You can look at Keysight’s 346A or B or Noisecom’s NC346A or B. I would recommend a 346B (or NC346B) for most testing, and if your gain is too high, pad it down at the output to around 20 dB for best results. The higher ENR generally provides better measurements, but not if you saturate your RF input.
Jan,
If you use Arthur’s suggestion, a parabolic phase relationship gives you the best dynamic range.The TG124A is only rated to -15 dBm. The TG44A goes to -10 dBm, though.
We do test each unit at their rated output power. It’s a tricky test, because we measure harmonics (which can be high), and then total output power with a thermal power sensor, and then calculate power at the fundamental frequency.
We do guarantee their accuracy (e.g. -15 dBm at 100 kHz should read -13 to -17 dBm on a suitable RF power meter). If you can make an accurate measurement at the RF output connector, and it is out of tolerance, this would be covered under warranty. January 29, 2021 at 5:17 pm in reply to: Discontinuity issue in Scalar Network Analysis using SA44B + TG44A Did you put a 6 dB attenuator on both the TG and the SA? It should align fairly well.
If you want more dynamic range, you could amplify the TG output. A good amplifier that covers your frequency range would eliminate the effect of SWR on the TG side. A gain of 10-20 dB, followed by the device under test, followed by a 10-20 dB attenuator to the SA should preserve dynamic range and give you excellent return loss on both the input and output for your device under test.
January 28, 2021 at 10:07 am in reply to: Discontinuity issue in Scalar Network Analysis using SA44B + TG44A SY,
This is likely due to impedance steps in the TG and SA. Although our systems are 50 ohms nominal, the SWR is not great in spots. This can be largely mitigated with a 6 dB fixed SMA attenuator on the TG and SA. Their attenuation will calibrate out, and should make any discontinuities all but disappear as your return loss will improve by 12 dB.Tyang,
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. December 3, 2020 at 9:38 am in reply to: TG44 standalone application (Amplitude and Refefence Option) The output power ranges from -30 to -10 dBm. Values outside this range are not expected to change amplitude. Additionally, the step size is about 1 dB but it will snap to the nearest measured value, so a step size of 2 dB is sometimes required to get an amplitude change. For finer amplitude control, consider one of our VSGs.
If nothing is connected to the 10 MHz in/out BNC, select “unused”The protocol to simply configure a center frequency contains commands to directly set registers on about a dozen different chips, writes values to FIR filters to optimize IF flatness and image rejection at the frequency selected, and digital tuners to center the frequency of the I/Q data. The API handles all of this behind the scenes.
The SA44B is designed for narrow-band signal measurement. However, if the task is simply to measure the power at the LNB and adjust the dish for maximum power, the SA44B can work for this. The SA44B cannot provide power. A bias tee can be used to provide power, but you must use a DC block because the SA44B front end is DC coupled.
DDR,
We digitally tune, so the frequency resolution is limited to a double precision floating point number (sub-Hz resolution). If you are asking about the tuning of the LO itself, we tune in 125/16 MHz steps (7.8125 MHz), and digitally tune from there. September 1, 2020 at 9:35 am in reply to: Using 10 dB coupler for return loss measurement & 20 dB pad placement Yes, but the scalar system for return loss only has the dynamic range of your coupler’s directivity, which is less than 40 dB. So it is not recommended to “store 20 dB pad” for return loss, only insertion loss.
August 31, 2020 at 12:06 pm in reply to: Using 10 dB coupler for return loss measurement & 20 dB pad placement Jeremy,
Your coupler will work fine. For return loss measurements, there is no reason to “store 20 dB pad” because 50 dB of dynamic range is more than enough for a return loss measurement.
For return loss measurements, if you have 3-6 dB SMA attenuators around, putting one on the TG and one on the BB can improve SWR which will make the measurements more accurate.Michael, this looks like the 140 MHz SAW band pass filter in the BB60C. Most of the ripple should generally be removed in our corrections, but there can sometimes be a little residual ripple which is somewhat worse as the device is warming up. Once the BB60C is fully warmed up, this ripple may be smaller.
Hopefully this helps. If you are looking for amplitude deviations smaller than 0.5 dB, you may need to wait for the device to warm up for 30 minutes, and then use trace math or some other mechanism to subtract out this baseline trace.
For what it’s worth, you should not see this ripple in the SM200B/C. We do not use any SAW filters, so the IF is smooth.