Test 500K to 30M

Projects LimeSDR
1

The broadband mode I used this time was intended to be used to test 500k-30m. When the frequency of the frequency band was input, I tested 1,2 points with the spectrometer until the signal strength did not decrease much.But when tested with lms7200, the results of spectrum measurement were not available. The software used was GUNRADIO,GQRX.image

2

Hi @liang12,

Test it using LimeSuiteGUI, please.

3

@Zack Thank you for your reply.Please tell me how to set the test bThank you for your reply.Please tell me how to set the test below 30M?

4

How does the limesuit choose the antenna and the NCO

5

Hi @liang12,

Let us assume we want to receive a signal at 20MHz. Then you have to perform these steps:

  1. Push “Default” button in LimeSuiteGUI after connected to the board.
  2. Set SXR frequency to 30MHz and push “Calculate”.
  3. Go to RBB tab and set “RF Bandwidth” to 120MHz.
  4. Go to CGEN tab, set required frequency and push “Calculate”.
  5. Go to RxTSP tab and uncheck “CMIX” option in “Bypass” group.
  6. Set FCW frequency to 10MHz and set “Upconvert” in “CMIX” group.
  7. Execute FFTViewer to check your signals.

To select Rx antenna go to RFE tab and then:

  1. To select RX1_H port, make sure “Active path to the RXFE” is set to “LNAH” and both “input of LNAL” and “input of LNAW” (in the “Input shorting Switches” group) are selected.
  2. To select RX1_L port, make sure “Active path to the RXFE” is set to “LNAL” while “input of LNAL” is unchecked and “input of LNAW” (in the “Input shorting Switches” group) is selected.
  3. To select RX1_W port, make sure “Active path to the RXFE” is set to “LNAW” while “input of LNAL” is selected and “input of LNAW” (in the “Input shorting Switches” group) is unchecked.
6

Thank you for your detailed answer. I have another question in practice. Is the required frequency in CLKGEN option the value of CLK_L?

7

CLK_L in this particular case indicates DAC/ADC sampling frequencies as well as RxTSP and TxTSP clock rates. As you can see, these are four times lower than CGEN frequency (aka CLK_H).

8

Thank you again for your reply.According to your Settings, I have been able to measure, and found that the frequency can be detected at 500k-30m frequency, but the signal strength will decline sharply below 9M. May I ask if this is the limit of LMS7002 or caused by the circuit mismatch in front of the chip?