Post Go back to editing

AD9361/71 as superheterodyne to support 1000 hops/Sec frequency hopping ?

Hi,

Our requirement is to operate a Wideband transceiver in 4.4 - 5 GHz band and hop it at a rate of 1000 hops/sec between 6000 channels in the band...I have look at both AD9361/71...Though AD9361 feature fast lock method for fast frequency hopping, this only works for channels which is within 100 MHz from the calibrated frequency (Analog Dev recommendation)...If we want to hop to a channel that is 100MHz far away from the calibrated frequency, calibrations such LoL and QEC has to be done...As these calibration takes time in milliseconds, we could not hop at 1000hops/Sec...

So, we came up with an idea which will operate AD9361/71 at a fixed intermediate frequency (2GHz) and a fast lock External LO (ADF4351) having 2.4 ~ 3 GHz range to do fast frequency hopping...Mixing both by make use of mixer will give a signal to our desired band 4.4 ~ 5 GHz...For example, assume AD9361 fixed intermediate frequency - 2GHz and External LO at 2.4GHz.Mixing this two will give their sum at 4.4 GHz which is our desired band of transmission...

Q1:

The above method is achievable with AD9361/71?

Q2:

Are there any limitations and performance degradations for AD9361/71 to implement the above method?

Please suggest...

Thanks,

Muthu



NC
[edited by: muthukural at 7:20 AM (GMT -4) on 26 Sep 2018]
  • AD9371/AD9361 has a direct conversion architecture which converts the RF directly to baseband and vice versa. You cannot operate it as a super heterodyne architecture which downconverts in two steps..

    If you are using a separate mixer and a separate LO source at the output of AD9361/AD9371 for fast frequency hoping(such  that AD9361 will operate at a particular frequency(2GHz)) ,then there will not be any problem from the chip side.

  • Hi Srimoyi,

    Thanks...Well, forgot the term "superheterodyne"...I am just seeing the following will work as expected.

    Instead of changing AD9361/71 RF carrier frequencies, we are going to fix it at one frequency says 2 GHz...Hence, AD9361/71's modulated signal at 2 GHz...This modulated signal will be mixed with fast frequency hopping external LO signal which is in the range of 2.4 ~ 3GHz to get 4.4 ~ 5 GHz band transmission...The below diagram is an example of transmission. For the receiver, RF signal (4.4 ~ 5 GHZ) and LO signal (2.4 ~ 3GHz) are the inputs to the mixer. The difference between them will be 2 GHz which is the required input at AD9361 Rx...

    Could you suggest the above is possible with AD9361/71 (Or) not?

    Thanks,

    Muthu

  • Yes. It is possible with AD9371/AD9361.