RSSI and RSRP on THINGY.91

[Hoang]

Dear, 

Im trying to measure the RSSI with THINGY:91, I found on the document  nrf91_at_commands_v1.1.pdf about

1. AT+CSQ

      +CSQ: <rssi>,<ber>

Note: Not detectable, RAT not supported. Use +CESQ and %CESQ for E-UTRA signal quality.

2. AT + CESQ 

    +CESQ: <rxlev>,<ber>,<rscp>,<ecno>,<rsrq>,<rsrp>

<rsrp>
0 – RSRP < −140 dBm
1 – When −140 dBm ≤ RSRP < −139 dBm
2 – When −139 dBm ≤ RSRP < −138 dBm
...
95 – When −46 dBm ≤ RSRP < −45 dBm
96 – When −45 dBm ≤ RSRP < −44 dBm
97 – When −44 dBm ≤ RSRP
255 – Not known or not detectable

I am using AT+CESQ to find RSRP 

and, i found some document about RSRP range: 

https://wiki.teltonika.lt/view/RSRP_and_RSRQ

But, when I tested to measure it, i got: 

I set the devices (3) in my freezer, and got the RSRP < -100dBm, 

is it conflict here? On the document, they say: NO signal when RSRP < -100dBm, but, I measured -120dBm, and I still received the data from my THINGY:91 - it means : still signal 

I am using Telia NB-IOT( Unit1) Telia LTE-M(Unit2) and Telenor LTE-M(Unit3)

My question is: RSRP vs Signal strength range? RSRP for no signal?

Thanks 

BR, 

Hoang Nguyen

[Hoang]

No, just use internal one

[Hoang]

if we want the external antenna, which one should we use? do you have any suggestion 

[Hoang]

Hi Hakon

I hope you will have time for me today. 

1. With the external antenna, which one is suitable for THINGY:91 ( NB-IoT Telia) 

2. Go back my problem

Hoang said:

My problem: when the signal is bad (RSRP < -130 dBM), it stopped working and couldnt reconnect at kl.19.24. 

At kl.13.20 , it did NOT send any package (because of bad signal), then, it sent again 14.23. 

when the signal is bad (lost) for a long time, it couldnt reconnect, and just hang there. Have you met this problem before?  

        1.  I tried to put the thingy91 in a metal-box ( simulated for bad signal)

        2.  it stopped sending because of bad signal, if:

                   2.1.  10mn, took thingy out, it reconnected automatically and resent the package

                   2.2.  3hrs, took thingy out, I didnt receive any data from my thingy - it could NOT reconnect and resend the data !!!

Does error_handler() work correct in this case? 

/**@brief nRF Cloud error handler. */
void error_handler(enum error_type err_type, int err_code)
{
	/*if (err_type == ERROR_CLOUD) {
		if (gps_control_is_enabled()) {
			printk("Reboot\n");
			sys_reboot(0);
		}
                */
#if defined(CONFIG_LTE_LINK_CONTROL)
		/* Turn off and shutdown modem */
		printk("LTE link disconnect\n");
		int err = lte_lc_power_off();
		if (err) {
			printk("lte_lc_power_off failed: %d\n", err);
		}
#endif
#if defined(CONFIG_BSD_LIBRARY)
		printk("Shutdown modem\n");
		bsdlib_shutdown();
#endif
	}

#if !defined(CONFIG_DEBUG) && defined(CONFIG_REBOOT)
	LOG_PANIC();
	sys_reboot(0);
#else
	switch (err_type) {
	case ERROR_CLOUD:
		/* Blinking all LEDs ON/OFF in pairs (1 and 4, 2 and 3)
		 * if there is an application error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_CLOUD);
		printk("Error of type ERROR_CLOUD: %d\n", err_code);
	break;
	case ERROR_BSD_RECOVERABLE:
		/* Blinking all LEDs ON/OFF in pairs (1 and 3, 2 and 4)
		 * if there is a recoverable error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_BSD_REC);
		printk("Error of type ERROR_BSD_RECOVERABLE: %d\n", err_code);
	break;
	case ERROR_BSD_IRRECOVERABLE:
		/* Blinking all LEDs ON/OFF if there is an
		 * irrecoverable error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_BSD_IRREC);
		printk("Error of type ERROR_BSD_IRRECOVERABLE: %d\n", err_code);
	break;
	default:
		/* Blinking all LEDs ON/OFF in pairs (1 and 2, 3 and 4)
		 * undefined error.
		 */
		ui_led_set_pattern(UI_LED_ERROR_UNKNOWN);
		printk("Unknown error type: %d, code: %d\n",
			err_type, err_code);
	break;
	}

	while (true) {
		k_cpu_idle();
	}
#endif /* CONFIG_DEBUG */
}

3. About the power consumption of thingy91: have you ever measured the power consumption on thingy when the signal is bad ( RSRP = -130 dBm -- -110dBm). Do you have any document about this one

Thanks a lot

MVH

Hoang Nguyen

[Hakon]

Hoang said:

1. With the external antenna, which one is suitable for THINGY:91 ( NB-IoT Telia) 

 Which frequency bands are you going to use? The ideal antenna will depend on the frequencies.

[Hoang]

Hakon said:

Which frequency bands are you going to use? The ideal antenna will depend on the frequencie

1. Telia NB IoT (800 MHz): 801-811 downlink 842-852 uplink

2. Telia NB IoT (1800 MHz): 1745-1765 downlink 1840-1860 uplink