FlexRadio
OscarWatch treats duplex-capable Flex radios as a single satellite radio. It connects directly to the radio on the LAN using Flex’s SmartSDR TCP/IP API (not by automating the SmartSDR for Windows application). Full duplex is enabled on the radio, with separate RX and TX slices for Doppler.
What you need
- A dual-SCU Flex for true full duplex. Current Signature Series examples: 8600 / 8600M. Supported dual-SCU 6000-series radios include 6600, 6600M, and 6700.
- The radio on the same LAN as the PC (API discovery/control on UDP/TCP port 4992).
- Transverters and antenna ports wired for your satellite bands (see Antenna ports by band below).
Single-SCU models (for example 8400 / 8400M, or a legacy 6400) are not suitable for full-duplex satellite work. Settings shows a warning if discovery reports such a model.
Easy setup
- Open Settings → Radio, enable the radio, and leave Dual radio off.
- Choose FlexRadio (SmartSDR).
- Click Refresh next to Discovered radios (UDP discovery on port 4992).
- Select your radio — host and port fill in automatically (or type the IP yourself).
- Configure Antenna ports by band if you use separate RX A/RX B or ANT/XVTR paths for 2 m and 70 cm (optional; see below).
- Click Test SmartSDR connection to confirm the TCP API handshake with the radio.
- Track a pass — OscarWatch enables full duplex and drives RX/TX slices on the radio.
How OscarWatch maps VFOs
| OscarWatch | Radio (SmartSDR API) |
|---|---|
| Main (RX) | Downlink slice frequency, mode, and optional RX antenna |
| Sub (TX) | Uplink slice (tx=1), mode, FM CTCSS, and optional TX antenna |
| Satellite mode | full_duplex_enabled=1 and a two-slice layout |
Continuous Doppler uses slice tune … autopan=0 so the radio does not yank both panadapters onto one band every few seconds. When a satellite (or mode) is focused, OscarWatch binds each slice onto the correct VHF or UHF panadapter. A V/U↔U/V layout flip recreates slices with slice create … pan= (the API rejects slice set … pan=, and slice m cannot safely swap two occupied pans). Same-layout satellite changes keep a healthy bind and only retune. If you start with a single panadapter, OscarWatch allocates the missing band pan over the API (a short-lived opposite-band slice, or display panafall create when that can land on the needed SCU) before binding the peer slice, then centres and locks VHF/UHF pans from live centres. OscarWatch then tunes, centres the VHF and UHF panadapters once each (by locked SCU band, not by which slice happened to be attached), and sends autocenter=0 so the radio does not recentre them during Doppler. Modes (USB downlink / LSB uplink on linear SSB) are applied next. OscarWatch then reads back live RX/TX slice frequencies, modes, TX roles, and pan attachments, and retunes / force-rebinds if anything landed wrong. Pan centres are checked against the pass frequencies (not only the band), and recentred when a slice would sit visibly off-pan. After setup it marks the downlink slice active=1 so SmartSDR focus stays on RX for click-to-tune (uplink remains tx=1). FM CTCSS is programmed only on FM uplink modes.
OscarWatch keeps band-locked pans: VHF frequencies stay on the VHF panadapter and UHF on the UHF panadapter (important when one pan is an XVTR). Panadapter window order in SmartSDR for Windows (which pan is on top) is GUI-only — drag the title bar, maximise, or load a Global Profile. If you prefer the downlink always on the top panadapter, arrange that in SmartSDR yourself; OscarWatch cannot reorder GUI windows over the API.
Pass layouts
- Cross-band and same-band duplex (both uplink and downlink set, e.g. ISS packet): full duplex on, two slices. Same-band does not use classic split; Doppler still separates TX and RX on the two slices.
- Beacon / receive-only (uplink 0): full duplex off; only the downlink slice is tracked (RX antenna mapping still applies when configured).
If both panadapters stick on one band
After rapid U/V ↔ V/U satellite switching, SmartSDR can occasionally leave both panadapters on VHF or both on UHF. OscarWatch detects that from live pan centres and tries to restore a dual-band layout over the API: it recentres a candidate pan when the radio will take the move (never sending a cross-SCU centre that would collapse the only UHF pan onto 2 m), allocates a missing-band pan via a temporary slice (or display panafall create when that SCU can take the band), and only removes duplex slices if that first pass still cannot restore both bands. If you start with two panadapters already on different HF bands (both on the VHF-group SCU), OscarWatch frees one pan then allocates a UHF pan the same way. A single HF pan/slice start is also supported: OscarWatch will not keep retrying slice create against a stale pan stream id, and will drag a stuck HF pan onto 2 m via a short autopan=1 slice tune when display pan set … center= ACKs but the display does not move. Continuous Doppler still uses autopan=0 so those pans are not yanked again during the pass.
If recovery still fails (for example the radio is at pan/SCU capacity, or another Multi-Flex client owns the only available pans):
- In SmartSDR for Windows, load a Global Profile that restores your normal dual-pan layout (separate VHF and UHF pans, for example a “VU” or satellite profile you already use).
- Re-select the satellite in OscarWatch so pass setup runs again.
Keeping such a Global Profile handy remains useful as a last-resort recovery. Antenna port mapping in OscarWatch is optional and separate from this pan layout recovery.
Antenna ports by band
When you switch between U/V and V/U satellites, OscarWatch retunes both slices but the radio does not automatically move auxiliary receive ports. If your UHF transverter is on RX A and VHF on RX B, you can map those in Settings so the correct port is selected when OscarWatch initialises the duplex layout.
Ports are applied whenever a satellite (or mode) is focused and CAT pass setup runs, including below the horizon when you swap birds for testing. You do not need the satellite to be above the horizon.
Under Settings → Radio → FlexRadio, the Antenna ports by band section offers four optional mappings:
- VHF receive (2 m) and UHF receive (70 cm+): applied by band to each slice's
rxant(the VHF slice and the UHF slice). - VHF transmit (2 m) and UHF transmit (70 cm+): applied to the uplink slice (
txant).
Choose Leave unchanged for any row you do not want OscarWatch to touch (the default for all four). Valid API port tokens are ANT1, ANT2, RX_A, RX_B, and XVTR (shown in Settings as RX A / RX B).
RX A and RX B are receive-only auxiliary ports, typical for transverter IF inputs. Transmit paths usually use ANT1, ANT2, or XVTR; map TX only if your station switches those by band.
Example (transverters on RX A / RX B)
| Setting | Value |
|---|---|
| VHF receive | RX B |
| UHF receive | RX A |
| VHF / UHF transmit | Leave unchanged (or ANT/XVTR as wired) |
Wiring is station-specific. Dual-SCU models such as the 8600 / 8600M (and dual-SCU 6000-series radios) can expose RX A/RX B when fitted, but which band goes to which port is yours to configure.
Tips
- SmartSDR for Windows (or Maestro) is optional for panadapter display and audio. OscarWatch talks to the radio as a separate API client whether or not that GUI is open.
- Keep a SmartSDR Global Profile with separate VHF and UHF pans as a last resort. OscarWatch normally restores dual-band pans over the API when both displays collapse onto one band; if that cannot run (capacity or another client owning the pans), load the profile, then re-select the satellite (see above).
- If Settings → Recording reports that audio is unavailable while SmartSDR for Windows is running, configure pass recording with that app closed — some DAX virtual audio devices fail PortAudio initialisation. OscarWatch probes audio in a separate process so this does not close the main application. Other Settings tabs are safe to use during a pass.
- This driver is not a dual-radio leg and is not Hamlib/rigctl.
- RF isolation and transverters remain your responsibility — OscarWatch controls frequency, mode, full duplex, tone, and optional antenna ports.
If the radio is discovered but not controlled
- Use Test SmartSDR connection; discovery uses UDP, while control needs TCP port 4992 to the radio.
- Confirm the radio is enabled, Pause CAT is off, OscarWatch is not in Standby, and a satellite with an uplink and downlink is focused.
- At pass start, confirm the radio has full duplex on and separate RX/TX slices (visible in SmartSDR for Windows if you use it, or via status/logs). OscarWatch reports a visible radio status if either step fails.
- If control still fails, use Help → Open logs folder and include the current log with your report. Flex discovery, connection, full-duplex and slice setup are recorded there.
Hardware smoke checklist
- Discovery lists the radio; Test connection succeeds.
- On pass start, full duplex is on and two slices are active.
- RX and TX Doppler both update during a pass.
- FM satellites get the correct uplink CTCSS.
- When antenna port mapping is configured, switching U/V ↔ V/U selects the expected RX (and TX) ports on the radio.