jjoonathanParticipantjjoonathan February 7, 2021 at 9:49 am
Hi! I just bought a SM200B and I absolutely love it. The sweep speed is phenomenal and having real time / phase noise / demodulation / EMC available in the base unit rather than locked behind an option really makes it a next-level experience.
I had a moment of concern when I was first acquainting myself with the Spike software, though. I noticed that Settings>Preselector was disabled by default. “Oh no,” I thought, “they have gone to so much trouble to design those filter banks — there must be a severe hidden caveat if they bypass them by default.” After experimenting with some 500MHz wide noise-like signals I think the actual situation is that preselection is always enabled, regardless of whether or not the preselector menu item has a check next to it or not. I’d appreciate confirmation that this is in fact the case, and if so I would like to put in a feature request for the menu item to reflect the state of the instrument. If there is a hangup with having a menu item disabled in the checked state, a grayed out “Preselector Enabled” would suffice.
Aside from that hickup, though, I love everything about my new SM200B!
AndrewModeratorAndrew February 8, 2021 at 8:20 am
Glad to hear that you love your new SM200B. That’s great!
Regarding preselectors, check out section 3.3 of the product manual linked below for the full description.
Above 645MHz, the preselector filters are always on, since we have enough filter overlap to measure at any of those frequencies with any IF bandwidth. The narrower filters below 645MHz are the ones that are controlled with the preselector control. For sweeps, enabling the preselector will slow down the sweep for the benefit of the extra filtering. For I/Q streaming and real-time measurement applications, enabling the preselector means we can only enable a single filter. In these situations, you can refer to the filter list in the above manual to see which filter is used at specific frequencies.
I hope this helps. Let us know if you have further questions.
jjoonathanParticipantjjoonathan February 8, 2021 at 1:58 pm
Makes sense, thanks!
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