Only For Mini Duplex Board Set Up Pi-Star Software And for Raspberry Hardware (RPI 0-3) New Pi4B Needs To Delete Right Socket Pi-Star General Configuration Of Mmdvm_duplex Set Controller Mode: Duplex Repeater Or Simple The Default Bit Error Rate Is Less Than 5%, And The Default Offset Is 0. If The Bit Error Rate Is 5%, As Long As The Signal Can Be Received, It Can Be Corrected Through Offset. Radio frequency: Freq:144-148, 219-225, (main frequency band) 420-475, 842-950 Duplex mode:Example:RX:438.000000 TX:433.000000 Duplex mode:Example:RX:145.000000 TX:433.000000 Simple mode:Example:RX:438.000000 TX:438.000000 Radio/Modem Type:STM32-DVM/MMDVM_HS- Hat(GPIO) or any other (GPIO board) AdminExpertEdit MMDVMHOSTRXOFFSET=0 TXOFFSET=0 (default value in pistar) (Update:2019/2 new 3225 TCXO so the offset is 0) Update new firmware:(pi-star / Expert / ssh access / user :pi-star pass:raspberry) sudo pistar-mmdvmhshatflash hs_dual_hat Note:Different Batches May Have Differences In Product Appearance, Color, And Printed Characters, Which Will Not Affect The Use Colour:As Shown Material:PCB Package Contents: 1 * Hotspot Board Module 2 * Pin Header Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.