| Electronics > Projects, Designs, and Technical Stuff |
| DIY 1.8GHz spectrum analyzer |
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| erikka:
Hi all, I want to share my latest project, a 1.8GHz spectrum analyzer. Technology (see first picture): Double/triple conversion with passive mixer modules from eBay and ADF4351/SI5351 modules from ebay as LO's Log amp (from AD8307 data sheet) for DIY wide RBW and audio based FFT stitching for small RBW Arduino zero for embedded control and everything else on PC SW also DIY based on .net so PC only Specs: DC (I tested down to 10 Hz) till 1.8GHz IIP3 +18dBm (see second picture) Spur free dynamic range (depending on RBW) at least 70dB RBW from 300kHz to 1Hz (See third picture) Dynamic range reduced (but still acceptable) at small RBW due to phase noise of ADF4351 Phase noise acceptable (see fourth picture) And results of an actual measurement of harmonics of a signal generator as fifth picture (ignore the IIP3 text at top of display, forgot to switch of) All still without shielding so you may notice some spurs |
| Theboel:
Very interesting with max2871 and etc chip get higher is that possible You made this an open project ? |
| ogden:
Wow. Fine job! Could you show some photo of instrument as well? What is RBW and what Resolution? In case RBW is Resolution Bandwidth, in one screen it is 30KHz while span is 20KHz. How's that? |
| erikka:
The RBW is the selected hardware filter bandwidth at 2nd IF. The actual resolution is displayed at the bottom It goes from 300kHz an 30kHz for the hardware filters and from 10kHz down to 1Hz in FFT mode So in FFT mode with 20kHz span and 10k points you get 2Hz bins |
| erikka:
--- Quote from: Theboel link=topic=191295.msg2462010#msg2462010 ---with max2871 and etc chip get higher is that possible --- End quote --- I guess yes. --- Quote --- You made this an open project ? --- End quote --- There are no pcb designs or detailed documentation. It is more inspiration . I am still learning |
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