Signal Parameters for Measuring Signal Strength and Quality

Signal parameters are critical for assessing and optimizing the performance of modern communication networks. These parameters, derived through Quectel's AT commands measure signal strength, quality, and related environmental factors across GSM, WCDMA, LTE, CDMA, and EV-DO networks. Silbo Networks routers employ these commands to ensure superior connectivity and reliability under varied operational conditions.

1. RSSI (Received Signal Strength Indicator):
   • Measures the overall strength of the received signal, expressed in decibels (dBm).
   • Higher (less negative) values indicate a stronger signal.
2. RSRP (Reference Signal Received Power):
   • A precise measurement of the power of the reference signal received from the cell tower.
   • Commonly used in advanced cellular technologies like LTE.
3. RSRQ (Reference Signal Received Quality):
   • Evaluates the quality of the received reference signal by considering modulation errors and other factors.
   • Helps assess signal reliability.
4. SINR (Signal-to-Interference plus Noise Ratio):
   • Represents the ratio of the desired signal strength to the combined strength of interference and noise.
   • A key indicator of call quality and network performance.
5. SNR (Signal-to-Noise Ratio):
   • Measures the ratio of the desired signal strength to the background noise level.
   • Higher SNR values indicate better signal clarity.

2G	RSSI	Signal strength
	>= -70 dBm	Excellent
	-70 dBm to -85 dBm	Good
	-86 dBm to -100 dBm	Fair
	< -100 dBm	Poor
3G	RSSI	Signal strength
	>= -70 dBm	Excellent
	-70 dBm to -85 dBm	Good
	-86 dBm to -100 dBm	Fair
	< -100 dBm	Poor
4G	RSRP	Signal strength
	>=-85 dBm	Excellent
	-86 dBm to -95 dBm	Good
	-96dBm to -110 dBm	Fair
	< -110 dBm	Poor
5G	RSRP	Signal strength
	>= -85 dBm	Excellent
	-86 dBm to -95 dBm	Good
	-96dBm to -110 dBm	Fair
	< -112 dBm	Poor

AT Commands

AT+QCSQ Command: Signal Strength Measurement

The AT+QCSQ command is utilized to query and report the signal strength of the current service network. This command is designed to function in multiple network modes, allowing both active querying and unsolicited reporting based on signal strength changes.

Key Parameters

• <sysmode>: Indicates the service mode (e.g., GSM, LTE).
• <value1> to <value5>: Represent signal strength and quality metrics specific to each service mode.
  • GSM: gsm_rssi (Received Signal Strength Indicator).
  • WCDMA: Includes wcdma_rssi, wcdma_rscp, wcdma_ecio.
  • LTE: Includes lte_rssi, lte_rsrp, lte_sinr, lte_rsrq.
  • CDMA and EV-DO: Includes respective rssi, ecio, and sinr values.

Examples

1. Querying Signal Strength:
2. Supported Service Modes:

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AT+QTEMP Command: Temperature Monitoring

The AT+QTEMP command measures the temperature of critical hardware components, ensuring devices operate within safe thermal limits.

Key Parameters

• <pmic_temp>: Power Management Integrated Circuit temperature.
• <xo_temp>: Crystal oscillator temperature.
• <pa_temp>: Power amplifier temperature.

AT+CSQ Command: Basic Signal Quality Measurement

The AT+CSQ command is a fundamental tool used to measure signal strength and quality. It provides two key parameters:

• RSSI (Received Signal Strength Indicator): Measures the signal strength in dBm.
• BER (Bit Error Rate): Indicates the quality of the signal by measuring error rates.

Response Format

Parameter Details

• <rssi>: Integer value representing signal strength. A higher value indicates a stronger signal.
  • 0: -113 dBm or less (poor signal).
  • 31: -51 dBm or better (excellent signal).
  • 99: Not detectable.
• <ber>: Integer value representing bit error rate.
  • 0: Best quality.
  • 7: Worst quality.

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References

• Quectel AT Command Manual