Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

OFDM measurement problem using spectrum analyzer

Status
Not open for further replies.

wccheng

Full Member level 5
Joined
May 16, 2004
Messages
287
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,296
Activity points
2,710
Dear all,

I use the spectrum analyzer to measure the transmitted signal from the product. The signal is an OFDM in UWB mode 1. If I set the RBW in the spectrum analyzer is 1MHz, I could read the power mask of the signal is -41dBm. It is meet the FCC specification that the power mask need to be -41dBm/MHz.

However, I try to set the RBW < 1MHz. I find that the power level is decreasing. Why is it happen? Could anyone tell me why or give me some informations of the working mechanism of the spectrum analyzer?

Thanks

wccheng
 

noiseless

Full Member level 3
Joined
May 24, 2005
Messages
172
Helped
15
Reputation
30
Reaction score
6
Trophy points
1,298
Activity points
2,495
that is because for 1MHz RBW, the power level is for the whole 1MHz bandwidth signal power. When RBW is less than 1MHz, for example, 500kHz, the power level is for the 500kHz bandwidth. the whole bandwidth signal power is composed of wanted signal power plus noise power. If wanted signal power is much higher than the noise power, the change of the bandwidth will not affect signal power level too much. However, if wanted signal is not relatively very higher than the noise power, the change of the bandwidth will affect wanted signal power very much.
 
  • Like
Reactions: kydong

    kydong

    points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top