FlexRadio SmartSDR + fldigi Setup Guide

FlexRadio FLEX-6X00
    |
    +-- DAX (Audio) --> Virtual Sound Device --> fldigi Audio I/O
    |
    +-- CAT (Control) --> SmartCAT COM Port --> fldigi Transceiver Control

Enable DAX in SmartSDR

1. Open SmartSDR
2. Navigate to Configure → Config Dialog → Audio
3. Locate DAX Audio Devices section
4. Set DAX IQ and DAX PCM to active
5. Note device names (typically "DAX1" for TX, "DAX2" for RX)

Assign DAX to a Slice

1. Right-click on the Slice for digital modes
2. Select Configure Audio Path
3. Assign DAX TX for transmit audio input
4. Assign DAX RX for receive audio output
5. Set slice mode to DATA

Audio Level Configuration

TX Audio (Transmit):

• Maximum Safe Level: -1 to -3 dB on SmartSDR LEVEL meter
• DAX TX Slider: Start at 44-46
• Key Rule: Never drive audio into RED (0 dB)

RX Audio (Receive):

• Audio Gain Slider: Start at -20 dB
• AGC: Enable for SSB/DATA slices
• Keep fldigi input between -20 and -10 dB

Create Virtual COM Port

1. Download and install SmartCAT from FlexRadio Software Portal
2. Open SmartCAT
3. Click ADD to create new port configuration
4. Configure:
   • Port Name: "FlexRadio Slice A"
   • Port Type: SERIAL
   • FlexVsp: Check this box
   • Note the COM port number assigned (e.g., COM4)
5. Slice Assignment: Select the slice fldigi will control (typically Slice A)
6. Click Apply

RigCAT XML Files

FlexRadio provides per-slice XML files:

Location: C:\Program Files\FlexRadio Systems\SmartSDR\rigs\

RigCAT Setup Steps

1. Open fldigi
2. Navigate to Configure → Config Dialog → Rig Control
3. Check: "Use RigCAT"
4. Click Browse, navigate to SmartSDR rigs folder
5. Select SmartSDR_SliceA.xml
6. Device: Select your SmartCAT virtual COM port (e.g., COM4)
7. Configure PTT:
   • Check: "CAT Command for PTT"
   • Check: "VSP Enable"
   • Do NOT check DTR or RTS
8. Retries: 3, Retry Interval: 100ms, Command Interval: 50ms
9. Click Initialize - should show "Connected to Rig"

Audio I/O Settings

1. Open Configure → Config Dialog → Soundcard
2. Capture Device: Select DAX Audio Device
3. Playback Device: Select DAX Audio Device
4. Sample Rate: 48000 Hz

Olivia Mode Configuration

1. Mode Menu: Select Olivia → Olivia 16/500 (or 8/250, 32/1000)
2. Olivia signal appears as 8-32 distinct tones on waterfall
3. Tune so tones are centered
4. TX Audio: Peak at -1 to -3 dB on SmartSDR LEVEL meter

Local Area Network (LAN)

• Connect FlexRadio to LAN switch via Ethernet (NOT WiFi)
• Assign static IP or use DHCP reservation
• SmartSDR auto-discovers radio on LAN
• Multiple fldigi instances can operate on different slices

Remote Operation (WAN)

Option 1: VPN (Recommended)

• Set up VPN server at radio location (ZeroTier, WireGuard, OpenVPN)
• Remote PC connects to VPN
• Radio appears as local device

Option 2: SmartLink Cloud Service

• Create SmartLink account (free)
• SmartSDR discovers and connects via cloud
• Remote PC still runs SmartCAT for fldigi