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RS-UV3A

Squelch & Tone Commands

SQ – Squelch Level

Section titled “SQ – Squelch Level”

Sets the RSSI-based squelch threshold.

Syntax

Section titled “Syntax”
SQn
SQ?

Parameters

Section titled “Parameters”
ValueDescription
0Squelch always open (hear noise)
1–8Progressively tighter squelch
9Squelch always closed (muted)

Default

Section titled “Default”

3

Examples

Section titled “Examples”
SQ3             # Default setting
SQ0             # Open squelch (monitoring)
SQ6             # Tight squelch (strong signals only)
SQ?             # Query current level

Notes

Section titled “Notes”
  • Lower values = more sensitive (opens on weaker signals)
  • Higher values = tighter (requires stronger signals)
  • Use SQ0 for weak signal work or monitoring
  • Use higher values in noisy environments
Section titled “Related Commands”
  • SR — Extend squelch range
  • SO — Query squelch state

SR – Squelch Range

Section titled “SR – Squelch Range”

Extends the squelch threshold range for weak signal operation.

Syntax

Section titled “Syntax”
SRn
SR?

Parameters

Section titled “Parameters”
ValueDescription
0Normal range
1Extended range (+30 dB)

Default

Section titled “Default”

0

Examples

Section titled “Examples”
SR0             # Normal range
SR1             # Extended range for weak signals
SR?             # Query current setting

Notes

Section titled “Notes”
  • SR1 adds 30 dB to the current squelch setting
  • Useful for DX work or satellite communications
  • Combine with low SQ values for very weak signal reception

SO – Squelch Status

Section titled “SO – Squelch Status”

Reports whether the squelch is currently open or closed.

Syntax

Section titled “Syntax”
SO

Response

Section titled “Response”
SO: 0           # Squelch closed (no signal)
SO: 1           # Squelch open (signal present)

Notes

Section titled “Notes”
  • Works with both RSSI and CTCSS squelch
  • Useful for external controllers to detect activity
  • No parameters, query only
Section titled “Related Commands”
  • SQ — Set squelch level
  • TM — CTCSS mode setting

TF – CTCSS Frequency

Section titled “TF – CTCSS Frequency”

Sets the CTCSS (PL) tone frequency for encode and decode.

Syntax

Section titled “Syntax”
TFnnnnn
TF?

Parameters

Section titled “Parameters”
ParameterDescription
nnnnnTone frequency × 100 (5 digits)

Default

Section titled “Default”

13180 (131.8 Hz)

Examples

Section titled “Examples”
TF10000         # 100.0 Hz
TF08850         # 88.5 Hz
TF13180         # 131.8 Hz
TF14620         # 146.2 Hz
TF?             # Query current tone

Standard CTCSS Frequencies (Hz)

Section titled “Standard CTCSS Frequencies (Hz)”

67.0, 71.9, 74.4, 77.0, 79.7, 82.5, 85.4, 88.5, 91.5, 94.8, 97.4, 100.0, 103.5, 107.2, 110.9, 114.8, 118.8, 123.0, 127.3, 131.8, 136.5, 141.3, 146.2, 151.4, 156.7, 162.2, 167.9, 173.8, 179.9, 186.2, 192.8, 203.5

Notes

Section titled “Notes”
  • All 5 digits required (TF10000 not TF100)
  • Same frequency used for TX encode and RX decode
  • Must enable with TM command to take effect
Section titled “Related Commands”
  • TM — Enable CTCSS
  • TS — Tone decode sensitivity

TM – Tone Mode

Section titled “TM – Tone Mode”

Enables or disables CTCSS encoding and tone squelch.

Syntax

Section titled “Syntax”
TMn
TM?

Parameters

Section titled “Parameters”
ValueDescription
0Off (no CTCSS)
1Encode only (TX tone, no tone squelch)
2Encode + decode (TX tone + tone squelch)
3DCS mode (if supported by firmware)

Default

Section titled “Default”

0 (Off)

Examples

Section titled “Examples”
TM0             # No CTCSS
TM1             # Encode tone on TX only
TM2             # Encode tone + require tone to open squelch
TM?             # Query current mode

Use Cases

Section titled “Use Cases”
ModeUse Case
TM0Open repeaters, simplex
TM1Repeater requires PL, hear all traffic
TM2Only hear stations with your PL tone

Notes

Section titled “Notes”
  • TM1 sends tone but doesn’t require it to receive
  • TM2 provides selective calling capability
  • Tone frequency set by TF command

TS – Tone Sensitivity

Section titled “TS – Tone Sensitivity”

Sets CTCSS decoder sensitivity for tone squelch.

Syntax

Section titled “Syntax”
TSx
TS?

Parameters

Section titled “Parameters”
ValueDescription
LLow sensitivity
MMedium sensitivity
HHigh sensitivity

Default

Section titled “Default”

L (Low)

Examples

Section titled “Examples”
TSL             # Low sensitivity (default)
TSM             # Medium sensitivity
TSH             # High sensitivity
TS?             # Query current setting

Notes

Section titled “Notes”
  • Higher sensitivity = detects weaker tones
  • May cause false triggers on noise with TSH
  • Use TSM or TSH if tone squelch is unreliable
  • Only affects RX tone detection, not TX encoding
Section titled “Related Commands”
  • TM — Enable tone squelch
  • TF — Set tone frequency