rs-uv3a/src/content/docs/reference/commands/system.md

title	description
System Commands	Power, status, and configuration commands for the RS-UV3A

TX – Transmit

Controls the transmitter.

Syntax

TXn

Parameters

Value	Description
0	Stop transmitting (return to RX)
1–5	Transmit with n-minute timeout

Examples

TX1             # Transmit, 1 minute max
TX3             # Transmit, 3 minute max
TX0             # Stop transmitting

Notes

• TX0 stops TX even if hardware PTT is held
• Timeout overrides TO setting for this transmission only
• If TX is off, radio is in RX mode

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PW – TX Power

Sets the transmit power level.

Syntax

PWn
PW?

Parameters

Value	Power Level
0	Low (~10 mW, 10 dBm)
1	High (~200 mW, 23 dBm)

Default

1 (High)

Examples

PW1             # High power
PW0             # Low power
PW?             # Query current setting

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TO – Timeout

Sets the transmit timeout timer.

Syntax

TOnnn
TO?

Parameters

Parameter	Range	Description
nnn	000–600	Timeout in seconds
	000	Disable timeout

Default

000 (disabled)

Examples

TO180           # 3 minute timeout
TO300           # 5 minute timeout
TO000           # No timeout
TO?             # Query current setting

Notes

• All 3 digits required
• When timeout occurs, sends TG message and unkeys
• Protects against stuck PTT

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TG – Timeout Message

Sets the CW message sent when TX times out.

Syntax

TG<text>
TG?

Parameters

Parameter	Description
<text>	Message up to 7 characters

Default

'TO'

Examples

TGTIME          # Send "TIME" on timeout
TGTO            # Send "TO" (default)
TG?             # Query current message

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HT – Hang Time

Sets TX hang time for repeater applications.

Syntax

HTnnnn
HT?

Parameters

Parameter	Range	Description
nnnn	0000–5000	Hang time in milliseconds

Default

0000 (no hang time)

Examples

HT1500          # 1.5 second hang time
HT2000          # 2 second hang time
HT0000          # No hang time
HT?             # Query current setting

Notes

• All 4 digits required
• TX stays keyed for specified time after PTT release
• Used with courtesy beep in repeater applications

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CO – COR Inhibit

Sets the COR (Carrier Operated Relay) inhibit time.

Syntax

COnnnn
CO?

Parameters

Parameter	Range	Description
nnnn	0000–9999	Inhibit time in milliseconds

Default

0000

Examples

CO0150          # 150 ms inhibit
CO0200          # 200 ms inhibit
CO?             # Query current setting

Notes

• Prevents COR from going active briefly after TX ends
• Avoids squelch noise triggering COR
• Useful for packet and repeater applications

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CB – Courtesy Beep

Sets the courtesy beep for repeater applications.

Syntax

CBn
CB?

Parameters

Value	Beep
0	None
1	Low tone
2	High tone
3	High/low
4	Two tones

Default

0 (none)

Examples

CB0             # No beep
CB2             # High tone beep
CB?             # Query current setting

Notes

• Sounds after hang time expires
• Signals repeater is ready for next transmission

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VX – VOX

Enables or disables voice-operated transmit.

Syntax

VXn
VX?

Parameters

Value	Description
0	VOX off
1	VOX on

Default

0 (off)

Examples

VX1             # Enable VOX
VX0             # Disable VOX
VX?             # Query current setting

Notes

• Pressing PTT disables VOX
• Do not use with speaker-mic (RX audio will trigger TX)
• Sensitivity set by VL command

---

VL – VOX Level

Sets VOX sensitivity.

Syntax

VLn
VL?

Parameters

Value	Sensitivity
0	High (most sensitive)
1	Medium
2	Low (least sensitive)

Default

1 (Medium)

Examples

VL0             # High sensitivity
VL2             # Low sensitivity
VL?             # Query current setting

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BW – Bandwidth

Sets the channel bandwidth.

Syntax

BWn
BW?

Parameters

Value	Bandwidth
0	12.5 kHz (narrow)
1	25 kHz (wide)

Default

1 (25 kHz)

Examples

BW1             # 25 kHz (standard)
BW0             # 12.5 kHz (narrow)
BW?             # Query current setting

Notes

• Requires power cycle to take effect
• Use narrow for crowded bands
• Some repeaters require narrow bandwidth

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PD – Power Down

Controls the transceiver chip power.

Syntax

PDn
PD?

Parameters

Value	Description
0	Chip powered down
1	Chip powered on

Default

1 (on)

Examples

PD0             # Power down (saves ~70 mA)
PD1             # Power up
PD?             # Query state

Notes

• Reduces current by approximately 70 mA
• Radio cannot TX/RX when powered down
• Serial commands still work

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B1 – Baud Rate 1

Sets the baud rate for serial port 1 (USB/JP1/JP2).

Syntax

B1n
B1?

Parameters

Value	Baud Rate
0	1200
1	4800
2	9600
3	19200
4	38400
5	57600

Default

3 (19200)

Examples

B13             # Set to 19200
B15             # Set to 57600
B1?             # Query current setting

Notes

• Requires power cycle to take effect
• Reconnect terminal at new baud rate after power cycle

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B2 – Baud Rate 2

Sets the baud rate for serial port 2 (DB-9 I/O connector).

Syntax

B2n
B2?

Parameters

Same as B1.

Default

3 (19200)

Notes

• Only applies when EX1 (serial mode)
• Requires power cycle to take effect

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FW – Firmware Version

Reports the current firmware version.

Syntax

FW

Response

FW: 2.4A

Notes

• Query only, no parameters

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BL – Bootloader

Enters bootloader mode for firmware updates.

Syntax

BL

Notes

• RS-UV3A waits indefinitely for bootloader connection
• Power cycle required to exit without updating
• See Firmware Upgrade guide

---

SS – Signal Strength

Reads the current receiver signal strength.

Syntax

SS

Response

SS: -85

Value is in dBm.

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SN – Noise Level

Reads the current receiver noise level.

Syntax

SN

Response

SN: 1234

Notes

• Lower values indicate cleaner signal
• Raw value, not calibrated

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VT – Voltage

Reads the operating voltage.

Syntax

VT

Response

VT: 8.5V

Notes

• Reads the 8.5V internal rail
• Useful for monitoring power status

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TP – Temperature

Reads the PCB temperature.

Syntax

TP

Response

TP: 42

Temperature in °C.

Notes

• PCB temperature, not ambient
• Will be warmer during TX

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BS – Battery Status

Legacy command for battery charger status.

Syntax

BS

Response

BS: 0

or

BS: 1

Notes

• RS-UV3A Rev A does not have battery charging
• Included for compatibility with older RS-UV3 versions

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RR – Register Read

Reads an RDA1846S transceiver chip register. Advanced use.

Syntax

RRxx

Parameters

Parameter	Description
xx	Register address in hex

Response

Returns 16-bit hex value.

Notes

• For advanced debugging only
• Register documentation available online for RDA1846S

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RS – Register Set

Sets an RDA1846S transceiver chip register. Advanced use.

Syntax

RSxxyyyy

Parameters

Parameter	Description
xx	Register address in hex
yyyy	16-bit value in hex

Response

OK

or no response if failed.

Notes

• Can disrupt radio operation if used incorrectly
• For advanced debugging only
• Settings may not persist through power cycle