SimTX Guide/Troubleshooting

Problems in the SimTX desktop app, with the messages the app shows and what to do.

Signing in

Message	What to do
Device authorization expired; try again.	Press Sign in again and approve the device in the browser within the time shown.
Couldn't check sign-in	Check your internet connection and try again.
Sign in again to create and edit stations.	Press Sign in and approve the device again.
Sign in to transmit from a station	Transmitting needs a SimTX account. Press Sign in.

Connecting

Connection details for a good link to the server.

Message	What to do
No servers online	No server is running at the moment. Press Retry later.
Couldn't load the server list	Check your internet connection and press Retry.
Couldn't connect to a server	Choose another server, or try again later.
Not connected to a server	Press Connect in the top right of the window.

The connection strip in the top right shows the link quality: Good, Fair, Unstable, Poor, Not responding or Offline. Select it to see why:

Item	Trouble when
Server replies	The server has been silent for a while.
TX buffer at server	Below about 300 ms; listeners may hear gaps.
RX dropouts (1 min)	Your receive bridges lost data.
Reconnects (1 min)	The connection dropped and came back.
Jitter	Above about 80 ms.
Latency	Above a second.

Settings, Connection, Reconnect automatically reconnects after a drop.

Before Start TX

Messages beside Start TX block the start until fixed. Most have a button that fixes them.

Message	Fix
Create a station to transmit from	Create opens the station editor. See Stations.
Choose a station to transmit from	Choose one under Transmit from.
No frequency	Enter a Frequency.
Power must be above 0 W	Enter a Power (W).
Power is above the radio's cap	Use cap sets the power to the radio's power cap.
No audio file chosen	Press Choose… under Source.
No input device selected	Choose an Input device.
GNU Radio IQ port is invalid	Enter a port from 1 to 65535.
High SWR	Warning: only part of the power reaches the antenna. Change antenna, or adjust its length in the station editor.
No input devices detected	Warning: connect a microphone or audio interface. On macOS, allow SimTX under System Settings, Privacy and Security, Microphone.
The tracked satellite no longer exists	Warning: choose another target under Track a satellite.

Before Start RX

Message	Fix
No callsign	Enter a Callsign for ad-hoc listening.
Receive location is invalid	Pick on map, or enter the latitude and longitude.
Choose one of your stations or Choose a public station	Choose the station under Where you listen.
No center frequency, Sample rate must be above 0	Fill in Tuning.
rtl_tcp port must be 1 to 65535	Enter a valid rtl_tcp port.
Listen address must be an IP like 127.0.0.1 or 0.0.0.0	Correct the Listen address.
Bridge is reachable from your network, so anyone there can retune it	Warning: Local only sets the address to 127.0.0.1.

Session messages

The Sessions list shows each transmission's state and message. Transmitting lists the states.

Message	Meaning
Queued	All transmitter slots are taken. Leave it; it starts when a slot is free.
Rejected: and a reason	The server refused the start. The reason says why, for example Only the station's owner can transmit through it.
Failed: TX idle timeout	The audio source sent nothing for 15 seconds. Check the file or input device.
Failed: connection error	The connection to the server broke. Start the transmission again.
Reconnecting TX…	The app is restoring the session after a drop.
Reconnect failed: and a reason	The session couldn't be restored. Start it again.
Kicked: and a reason	The server ended the session, for example a moderator, a deleted station or a satellite reentry.

A banner across the top of the window shows notices from the server. A banner starting with Banned: means your address is banned; the text gives the reason.

Nothing heard

On the receiving side:

1. Check that the bridge is Running in the Bridges list.
2. Check that your SDR program is connected to the address and port shown under Bridge.
3. Check that the signal is inside the band: the Center frequency plus or minus half the Sample rate.
4. Set the SDR program's mode and bandwidth to match the transmission.
5. Consider propagation: distance, band and time of day decide whether a signal gets through. See Propagation Basics.
6. For a directional antenna, check where it points. See Rotators and tracking.
7. For a satellite, check that a pass is in progress and that Correct Doppler is ticked. A satellite low on the horizon can be hidden by hills.

On the transmitting side:

1. Check that the session is Running, not Queued or Paused.
2. Press Listen to own TX to check the audio.
3. Check the radio deck: BUF/s above zero, SWR/:1 low and FWD/W near the power you set.
4. Check that the listener is on the same server.

Catalog

Message	What to do
Connect to a server to browse the catalog.	Connect, then open the Catalog tab again.
No answer from the server.	Press Retry.
The server didn't send the files in 10 s.	Press Retry.
No answer from the server in 20 s; check the catalog before trying again.	Refresh the catalog to see whether the upload arrived before publishing again.
Publishing requires catalog.publish	Your account doesn't have permission to publish.

See also

• How to receive
• SWR and Transmitter Protection
• Power Amplifier Behaviour