[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] Flexrf AGC sensitive to noise ?

From: Matt Ettus
Subject: Re: [Discuss-gnuradio] Flexrf AGC sensitive to noise ?
Date: Fri, 25 Apr 2008 10:07:34 -0700
User-agent: Thunderbird (X11/20080226)

Per Zetterberg wrote:
Hi All,

I am trying to get some experience of flexrf1800. I am receiving a CW of
1766MHz (from a signal generator) and transmitting a wavefrom at a different
frequency. Now, changing the frequency of the outgoing signal from 1800MHz
to 1900MHz changes the estimated amplitude of ingoing signal by 0.5dB! (yes,
they shouldn't have anything to do with each other, and yes, the SNR is

You will get leakage from the transmitter into the receiver. When you bring the TX frequency closer to the RX, more of it will get through and will change the amplitude estimates. The RFX boards can do full duplex, but there are limitations to how close you can have the TX and RX.

Could it be that the level of the AGC control signal (of the AD8347) is
affected by the the TX circuitry ?

Not likely.

Can the AGC be switched off entirely ?

No, you need to have some voltage going to the variable gain amplifiers. It is not automatically controlled however, unless you make it so.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]