How to set the trasmit power of USRP?

[memooo]

Dear,

The price for external is very high and its not good solution for my project  another help please. I appreciated that

[cochenob]

The programmable gain on the front end of the WBX should get you halfway there or so (20-ish dB of gain?).  You'll need an external amp to get you all the way to 20 W though.  No other way around it.  If the MiniCircuits product line was too expensive...you may be disappointed by other vendors.  MiniCircuits is usually about as "off-the-shelf" as you can get.  A Google search for RF Power Amplifiers would be a good place to start.

[memooo]

I saw some external amplifier but it is expinsive ,I appreciated your help. I saw internal component but i cant open the usrp and connect it because the usrp and daguhterboard so expensive. Any idea ?? 

[memooo]

the previus message is send in wrong im sorry . I used usrp n210 with sbx daughterboard that supply 100mw>>20dbm output power  and periodic antenna with gain equal 5 dbi so as i know the recived power is less than 30 dbm , the RFID system need power at least 30 dbm to power up the tag which mean 1 W .

so if i change the antena the problem maybe solve ?????

[cochenob]

You don't need to open the inside to connect anything.  There is an amplifier integrated into the daughterboard that you have.  You can set the gain of that amplifier through the "Gain" field of the VI used to configure the transmitter (actually, the amplifier gain is fixed and you're configuring the settings of a programmable attenuator...same effect basically). 

However...as I mentioned...that integrated amplifier doesn't have enough gain to get you to the 20 W you need.  No looking at the inside of the radio will change that. 

If you aren't willing to buy a second external amplifier, then you'll have to settle for a lower output power.

[cochenob]

Sorry!  30dBm is 20V...not 20 W.  My fault. (units matter!).

I'm not as familiar with the SBX...but 20dBm is about the absolute max you can expect to get at max gain on the WBX.

[Sarah_Y]

The SBX can output about 20 dBm as well, but it depends on the frequency.  At max gain, all frequencies can output 15 dBm, some as high as 20.5 dBm (this will vary some from board to board and should be considered "typical" but not guarunteed).  I agree with cochenob, if you need greater than 20 dBm of output power, you will need to purchase an external amplifier.

[memooo]

yes the sbx output power is the same 20dbm and its the maximuim. If you change the gain to 32 it will give you the maximum power >>20dbm and we cant get the power we want >>30dbm , I cant decrease the power becuase as i mentiond im working on RFID system with passive tag so if the power not enough,the tag will not response to my usrp .So the final solution is an external amplifier ????

Really i appreciated your help its strong 

[memooo]

Thank you sarah for your commect , but i would like to ask about RFX900 daughterboard , it supply 200mw>>23dbm and the same problem like sbx not enough output power ,But when i read some papers the told us if we remove the the ISM filter the output power will increase to >>500mw. The main question is this information right and the SBX have ISM filter ,Becuase i research for this and find nothing .

I appreciate your help my freind 

Eng.Mahran

[memooo]

Dear All,

Can usrp N210 with sbx daghuter board send and recive at the same time