| Products > Test Equipment |
| SSA2021X - 20 dB attenuator sufficient? |
| << < (5/8) > >> |
| fnaumann:
Before I use newly purchased attenuator, I checked them with the TG. Especially their attenuation over the entire available frequency range. I don't do that before every measurement. And I know the meaning of Ref Offset. The advantage of fixed attenuators is safety. With variable attenuators, I am always afraid that they will accidently change their attenuator value and then kill the SA during a measurement. |
| tautech:
--- Quote from: fnaumann on February 09, 2024, 01:54:51 am --- --- Quote from: tautech on February 09, 2024, 01:26:10 am ---Certainly so depending on what you are doing however don't underestimate how sensitive a SA is, easily equivalent to any radio. --- End quote --- A measuring device that declares a max input level of 30 dBm and then issues an overload warning when the signal is -55 dB (E -5) weaker is suspect to me. And if a internal preamplifier activation in a menu can kill the device - such an option should not be able to be activated or should turn off by itself if it get critical. Surely that should be possible with such an expensive measuring device? And let's assume that I'm too stupid to be able to display the signal sensibly on the SSA2021X , then the automatic function "Auto Tune" - offered in a separate button - should be able to display a measurement signal reasonably sensibly (signal-to-noise ratio) and not as a small bump surrounded by a sea of noise. And why is this all possible out of the box for a device that only costs a fraction? --- End quote --- As yet we have not seen any screenshots from you showing settings that might trigger warnings. FYI max continuous signal is specified as: 30 dBm, 3 minutes, fc ≥10 MHz, att > 20 dBm, preamp off This is of course without external attenuators. As yet I prefer to control any instrument rather than let an Autotune process second guess my requirements therefore I have never used it, maybe I should get some experience with it. :-// |
| fourfathom:
In many cases an "overload" indication doesn't mean a damaging-level input, but just that the input level with the current attenuation and gain settings results in a signal that is causing the detector to clip or distort. It's not an input power problem, just a dynamic range problem that can be corrected by adjusting the attenuation or gain settings. No harm done. |
| pdenisowski:
--- Quote from: tautech on January 14, 2024, 09:19:02 am ---Once you go to just RF In signals you need be more careful as even a mobile phone nearby handshaking with a cell tower can send input levels beyond safe levels where you will be warned by the internal overload buzzer and OSD warnings. This is especially true when you have the Preamp set to ON which is when you need work with care. --- End quote --- If I remember correctly, max UE transmit power in LTE and 5GNR is +23 dBm. I lot of things would have to go wrong (so to speak) at the same time in order to see even +20 dBm at the analyzer input. And it's not just handshaking (I assume you mean RACH): theoretically the base station could power control the UE up to max transmit power at any time, although this is also very uncommon. I used to do cellular drive test measurements and I'm not sure I ever saw a UE power controlled up to max Tx power. That said, a nearby UE can absolutely overload the front end of an analyzer and cause distortion / intermod: I saw that many times while doing interference hunting in the field. But I've never heard of an analyzer being damaged by OTA signals from a nearby UE. Damage from overload when directly connected with cable? Oh yes :) |
| pdenisowski:
--- Quote from: fourfathom on February 09, 2024, 08:01:17 am ---In many cases an "overload" indication doesn't mean a damaging-level input, but just that the input level with the current attenuation and gain settings results in a signal that is causing the detector to clip or distort. It's not an input power problem, just a dynamic range problem that can be corrected by adjusting the attenuation or gain settings. No harm done. --- End quote --- Yes, exactly this. In fact, often I've seen what is clearly distortion caused by an overdriven input even BEFORE any kind of "overload" indication appears. |
| Navigation |
| Message Index |
| Next page |
| Previous page |