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Garth,
Yes, if you wanted to do this programatically, you could use the sa_api and tg_api. Do 2 sweeps, one with your reference through, and one with your DUT. For each point within the sweep, tune the TG then do a small (100 kHz span or smaller) sweep around the signal and find the max value. Subtract the 2 sweeps for your insertion loss. We created a support ticket for this issue, but I don’t know where it is in the queue, so a “DIY” TG sweep might be a good solution in the short run.Devjack,
We are looking into this. It does look like we clamp to 1 kHz in this mode, which I can see does not make sense for your measurement, especially since the TG itself has 10 Hz resolution.
Two potential workarounds while we investigate:
1) You can use linear interpolation to get a good estimate of the 3 dB points
2) You can exit scalar analysis mode, and just do a sweep with max hold. Then step the TG in finer steps using the TG control.
I apologize for the inconvenience.I believe the base license (without cross-correlation) is $99 / year. If you don’t need the new features, you can keep using your 3.xx version for free.
https://signalhound.com/products/advanced-phase-noise-measurement-tool-kit/Amedina,
If you have an external 10 MHz source, I would use it to drive both instruments’ 10 MHz input. If not, you can use the 10 MHz output from the SM200 to drive the VNA400. This will discipline the VNA clocks and frequency output. I would do this before you calibrate the VNA.CH,
The software-based image rejection does limit the usefulness of the SA44B. For scans wider than 200 kHz, any time there is energy 21.4 MHz above, and 21.4 MHz below, the frequency being scanned, a spur will show up there. Narrower scans (200 kHz or below) have the same issue, but at different offset frequencies.
All of this is fixed in a product like the BB60D, with excellent hardware-based image rejection.MMark,
Below about 160 MHz, the SM-series is in its direct conversion band. But in order to squeeze this into our normal I/Q signal processing, we do an upfront digital tune for some combinations of center frequency and bandwidth. This will ultimately move the pass band, and will digitally filter out some frequencies. If you email our support team, we can go into more specifics for your use case, but this might be what you’re observing.
Rlisboa,
For Spike feature requests, please email support@signalhound.com. We try to add features periodically, based on how many customers are requesting the feature. If there is a competitor’s product or application with these features, please include a link. Thank you!I believe there are 9 markers, and we do have a max hold line, as well as channel power features that might be better for channel monitoring. We have a separate interference hunting mode as well. But if you’re used to a specific piece of software that does exactly what you need, Spike will not have all of the features of a dedicated live broadcast spectrum monitoring application.
You can install the software and play with the demo to get a feel for how well the features will work for your application.Mehdi,
It is high on our list of requested features, but has not been implemented yet for the SP145.
Yes, if you aren’t planning on using 2.92mm cables, the 2.4mm to SMA would be a good choice.
Thank you for everyone’s feedback. We have indeed made a significant investment on our new and improved phase noise measurement tool to include many value added features such as auto signal search, spur rejection, peak tracking, amplitude noise measurements and even cross-correlated phase noise and VCO testing with the PN400.
For non-PN400 users, we hear you, and we are currently working on a long-term solution. In the meantime, we will continue to support customers using our legacy phase noise analysis mode. If you need to reinstall the legacy software for any reason, drop us a line at support@signalhound.com and we’ll send you a link.
Mehdi,
Signals present when the input is terminated are “residual responses” or sometimes “residual spurious”.
The specification for the BB60D is -120 dBm. This is one of the strengths of the BB60D.
The specification for the SP145 is -103 dBm, similar to the BB60C.
This is not directly related to the preselector, and is more closely related to filtering and isolation differences in the architectures.Roman,
We have some customers who use the PPS from an external GPS as the trigger input. This marks the sample in an I/Q stream at the top of the second. The time stamping requires a little more work on your part, as you would need to interface the GPS yourself and generate the time stamp based on trigger position.Mehdi,
The standard approach is a high pass (often with an attenuator) for checking harmonics without a preselector. There is still a bank of low pass filters before the mixer, but not before gain control, so you end up with harmonics that may be higher than they actually are. I think you can expect -40 dBc or better, but if you need 60 dB a high pass filter would be needed. Something like this would work for 2.4 GHz harmonic testing:
https://www.minicircuits.com/WebStore/dashboard.html?model=ZHFG-K4000%2BMehdi,
That’s a good summary. A preselector really helps eliminate spurious responses from out-of-band signals, but adds noise figure.
Our products with preselectors (BB60D and SM200) are ideal for spectrum monitoring and harmonics measurements.
Our low-IF architecture products (SM200 and SP145) have the best dynamic range and flattest IF, making them ideal for modulation analysis.
For many applications, preselection can be accomplished with an external band pass filter. Mini Circuits is a good source for these.Each product line is a bit different. But for all of them we have a “spur reject” mode (under settings) where two different LO frequency results are masked together to eliminate most spurs. For measuring CW signals this is a good approach, but you lose the real-time nature of measurements in this mode.
The BB60D, being a double conversion superhet, will probably have the most consistent behavior across frequency.
Also keep in mind the BB60D spur shown is -77 dBm. Your bottom picture has a spur of -78 dBm, you just don’t notice it because of the noise.
Edit: I should add that all of our spectrum analyzers, in real-time mode, use a larger set of LO frequencies than sweep mode.Mehdi,
I think this is a spur from the real-time mode. Sweep mode lets us choose optimal LO frequencies, but real-time mode does not. This can result in additional low-level spurs, like this -77 dBc spur you found.
If you suspect a spur in real-time mode, set your span to, say 20 MHz, and step your center frequency by 5 MHz. This will configure the LO for a new frequency and result in a different set of potential spurs. If the spur doesn’t move, it is much more likely to be real than if it does.Jay,
Our Audio Demod tool in Spike would be able to give you the exact frequency of the audio pilot tone, but unfortunately it clamps to 20 kHz. In normal swept mode your accuracy will be limited to your RBW. Marker peak, delta, next peak would give you the audio frequency +/- your RBW. An RBW of 1 Hz would give you a 1 Hz accuracy. If this is not accurate enough, the next step would be to either put in a request for us to increase the maximum audio frequency in the Audio Demod mode, or use the API and do the FM demod yourself.
The peak deviation can be viewed in zero span mode FM, as you did. Measuring a local max, then a local min, with markers, should give you a peak-to-peak deviation.I believe the SA124B uses a digital correction for its OCXO frequency (it is not a voltage-controlled OCXO like the SM200). For zero frequency error, put both the SA124B and the VSG on a common external 10 MHz reference.
If you selected an external reference on the VSG, and generated a 1 GHz signal, I would expect the signal to be off by more than 10 kHz if the external reference was not found.APetrovic,
We do not have any public plans to go to higher frequencies at this point. But we would love to hear about your application / use case if you’d be willing to share details. Email justin (at) signalhound.com
Thanks!