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RS-UV3A

Audio Commands

VU – Volume

Section titled “VU – Volume”

Sets the receiver audio volume.

Syntax

Section titled “Syntax”
VUnn
VU?

Parameters

Section titled “Parameters”
ParameterRangeDescription
nn00–39Volume level in 1 dB steps

Default

Section titled “Default”

12

Examples

Section titled “Examples”
VU15            # Set volume to 15
VU25            # Increase volume
VU?             # Query current volume

Notes

Section titled “Notes”
  • Both digits are required (e.g., VU05 not VU5)
  • Volume 10–15 recommended for DTMF decoding
  • Also affects audio on I/O connector pin 4
  • Hardware adjustment available via VR1 potentiometer
Section titled “Related Commands”
  • GM — Microphone gain
  • AF — Audio low-pass filter
  • HP — Audio high-pass filter

AF – Audio Low-Pass Filter

Section titled “AF – Audio Low-Pass Filter”

Enables or disables the audio low-pass filter.

Syntax

Section titled “Syntax”
AFn
AF?

Parameters

Section titled “Parameters”
ValueFilterPassband
0OFF300–5500 Hz
1ON300–2500 Hz

Default

Section titled “Default”

1 (ON)

Examples

Section titled “Examples”
AF1             # Enable filter (voice mode)
AF0             # Disable filter (wide audio for data)
AF?             # Query current setting

Notes

Section titled “Notes”
  • Use AF1 for normal voice communications
  • Use AF0 for packet radio, wider audio bandwidth needs
  • Filter reduces high-frequency noise on weak signals

HP – Audio High-Pass Filter

Section titled “HP – Audio High-Pass Filter”

Enables or disables the audio high-pass filter.

Syntax

Section titled “Syntax”
HPn
HP?

Parameters

Section titled “Parameters”
ValueDescription
0Low-frequency corner lower
1Low-frequency corner higher

Default

Section titled “Default”

1

Examples

Section titled “Examples”
HP1             # Enable high-pass (default)
HP0             # Disable for lower audio response
HP?             # Query current setting

Notes

Section titled “Notes”
  • Affects the low-frequency cutoff of the audio path
  • For voice, HP1 is typically preferred
  • For data modes, experiment with HP0 if low tones are important

GM – Microphone Gain

Section titled “GM – Microphone Gain”

Sets the microphone input gain.

Syntax

Section titled “Syntax”
GMnn
GM?

Parameters

Section titled “Parameters”
ParameterRangeDescription
nn00–15Gain level in 2 dB steps

Default

Section titled “Default”

10

Examples

Section titled “Examples”
GM10            # Default gain
GM15            # Maximum gain (hot microphone)
GM05            # Reduced gain (loud talker or line input)
GM?             # Query current setting

Notes

Section titled “Notes”
  • Both digits required (GM05 not GM5)
  • Affects microphone input on MIC pad and SPK/MIC jack
  • Does not affect TX audio input on I/O connector pin 1
  • Electret mic element powered by 3.3V bias (R6)

Adjusting for Proper Deviation

Section titled “Adjusting for Proper Deviation”
  1. Set GM to default (10)
  2. Transmit and monitor on another receiver
  3. If audio is weak, increase GM
  4. If audio is distorted, decrease GM
  5. Target: 3–5 kHz deviation for voice

GT – Tone Gain

Section titled “GT – Tone Gain”

Sets the gain for CW and DTMF transmitted tones.

Syntax

Section titled “Syntax”
GTnn
GT?

Parameters

Section titled “Parameters”
ParameterRangeDescription
nn00–15Gain level in 2 dB steps

Default

Section titled “Default”

8

Examples

Section titled “Examples”
GT08            # Default tone gain
GT12            # Louder tones
GT04            # Quieter tones
GT?             # Query current setting

Notes

Section titled “Notes”
  • Affects CW identification tones
  • Affects DTMF transmission tones
  • Affects sidetone if enabled (SD1)
  • Adjust to achieve proper deviation (typically 3 kHz for tones)
Section titled “Related Commands”
  • SD — Enable/disable sidetone
  • CS — CW speed
  • DD — DTMF duration

DP – Pre/De-emphasis

Section titled “DP – Pre/De-emphasis”

Enables or disables TX pre-emphasis and RX de-emphasis.

Syntax

Section titled “Syntax”
DPn
DP?

Parameters

Section titled “Parameters”
ValueDescription
0Pre/de-emphasis OFF (flat response)
1Pre/de-emphasis ON (standard FM)

Default

Section titled “Default”

1 (ON)

Examples

Section titled “Examples”
DP1             # Standard FM voice mode
DP0             # Flat response for data
DP?             # Query current setting

Notes

Section titled “Notes”
  • Standard FM uses pre-emphasis on TX and de-emphasis on RX
  • Pre-emphasis boosts high frequencies on transmit
  • De-emphasis cuts high frequencies on receive
  • For packet radio, DP0 may provide flatter audio response
  • 9600 baud packet typically requires DP0
Section titled “Related Commands”
  • AF — Audio low-pass filter
  • HP — Audio high-pass filter