[Discuss-gnuradio] Is it possible to have 2 TX x 1 RX MISO in GNU Radio

[Nick Iliev]

Hello,

 we have implemented a 2 TX x 1 RX MISO testbed with GNU Radio 3.4 and
USRP1 . Both transmitters are using at 2.4GHz ( actually tx1 uses
2.401GHz and tx2 uses 2.403GHz ) , and are sending data ( BPSK
modulated ) at the same time ( in the same time slot ).

The summation of both transmissions is causing problems at the receiver :
1 - the Costas PLL does not  appear to lock to a single frequency
2 - the MM bit-synchronizer does not appear to work

Has anyone attempted this type of MISO system with the default GNU
Radio 3.4 and USRP1 distribution ?

Our goal is to plot the constellation of all superimposed received
symbols but to achieve this we need a frequency-locked receiver and a
recovered ( bit-synchronous ) clock.

Han and Nick
UIC Wireless Lab