RAK7200 node, GPS tracker

PabloG · October 4, 2019, 4:25pm

I need to work OTAA.
When I work on AS923 worked fine in OTAA, on AU915 must work fine too.

gibbsji · October 4, 2019, 5:43pm

I’m using OTAA and if the join operation fails (usually due to the antenna/distance from access point), the join just says “failed” and then it never seems to retry. Anyone know how to make this thing retry the join every X amount of minutes? It’s not always going to be in range when it’s powered up so I need it to retry connecting to the network every so often.

Nicholas · October 8, 2019, 3:19am

hello！
Can you tell me which server you are connecting to? And can you send me the screenshots of the gateway and node you got when you failed to connect?

Nicholas · October 8, 2019, 6:13am

If you are using RAK7249, could you please send me the configuration screenshot of this interface?

Francisco · October 8, 2019, 2:02pm

Hi Jim @gibbsji . I have the same problem. Have you been able to fix it ?? Best regards

Ernestas · October 8, 2019, 2:56pm

Same with my rak7200. I use ttn.

gibbsji · October 8, 2019, 7:57pm

@Francisco & @Ernestas , as of 3.1.0.9 and setting at+set_config=lora:send_interval:2:10 it does seem to begin sending data without having to manual intervene, but you have to use send_interval:2:XX which essentially disables the sleep function and simply sends whatever it has ever XX seconds. Likely will negatively impact battery life, but at least it’s working. If you set the as yours as directed, you still have to wait for the GPS to either timeout or get a valid set of data points before the send process starts (so be patient on reboot). Also, you must be in range of the TTN access point. If it fails to join, send_interval doesn’t seem to matter. It doesn’t have a “try re-join” interval.

PabloG · October 9, 2019, 12:45pm

PabloG · October 9, 2019, 1:33pm

Now, when I start again in AU915 they joined good, all 5 trackers.
But the PayLoad are every time diferent and the trackers are static.

JeroenKl · October 11, 2019, 10:41am

Dear @Fomi,
Do you have time to check, measure?
Output power with:
at+set_config=lora:tx_power:5
and with
at+set_config=lora:tx_power:0

best regards,

Jeroen

Fomi · October 11, 2019, 2:51pm

Hi @JeroenKl,

Yes, we’ve measured it this week, and the result is same with you. I think it may because of the distance is short so that the RSSI is same.

JeroenKl · October 13, 2019, 5:32am

Thanks @Fomi,

Better is to measure the real output power in dBm for both config’s.
I don’t have equipment to test this, do you have?

BR,

Jeroen

Fomi · October 14, 2019, 3:42am

OK, i will ask my colleague to help me to measure it.

Fomi · October 14, 2019, 10:24am

Hi @JeroenKl,

We’ve measured it, and you can see the result as follow:

As you see, the first picture shows that the output power is 14.53 dBm while the power level is 0. The second picture show that the output power is 3.47 dBm while the power level is 7.

JeroenKl · October 14, 2019, 6:26pm

Thanks @Fomi, so we should use the setting: at+set_config=lora:tx_power:0

BR, Jeroen

pe1mew · October 15, 2019, 7:03am

Time for an update on my investigations:

RSSI comparisment using a reference antenna
I have opened the 7200 and replaced the antenna by a GP antenna. Than I collected RSSI data using remote gateways over an hour where the 7200 was sending at a one minute interval. After this hour I reused the same GP antenna and replaced the 7200 with a TTGO T-bone and collected again RSSI data on the same gateways. During measurement the antenna was at the same location in both situations.

The result shows that output power of the RAK7200 when set at TX power ‘0’ is equal to that of the TTGO T-beam.

Antenna measurement of RAK7200 internal antenna
Now the RAK7200 was opened In verified the internal 868 MHz antenna. The internal antennas carries the type number “ZX0282-X1” and is not resonant at 868 MHz but on 606, 1127, and 2327 MHz. Either the antenna resonance frequecy is affected by the plastic of the housing (very unlikely) or the antenna is one for 2,4 GHz and not intended for use at 868 MHz that is installed by mistake (Likely).

afbeelding

Consusion
My RAK7200 is fitted with the wrong antenna for 868 MHz and performs bad because of that.

gibbsji · October 15, 2019, 5:36pm

Just letting “someone” know, the most recent boot loader and firmware (3.1.0.10) has my US device connecting and automatically sending data and retrying when it’s not in range (Awesome!). Nice work. However, I had to use my external antenna to do it. I may be out of range for the small antenna. I don’t have the testing equipment to see. Like other forum posters, I’m a bit confused as to the effectiveness of the tx_power setting and the data rate settings.

pe1mew · October 15, 2019, 7:23pm

i have updated my RAK7200 to version 3.1.0.10 to keep up but see no real reason to do so yet.

gibbsji · October 15, 2019, 8:38pm

3.1.0.10 Error - When setting a manual lora:dr:1,2, or 3 (adr disabled) the SF is correct per the US table, but the bandwidth (bw) is coming in at 500 when it should be 125. This seems like it is only occurring on the join packets, so if there is a strong enough antenna for bw 500 the join will succeed, and then subsequent data will be sent with bw 125. Dropping the bw on dr:1,2, or 3 to what the standard dictates (125) may make it so the factory antenna will suffice, but right now it won’t do a successful join with that antenna at that bw setting.

xstff78 · October 16, 2019, 2:46am

I like the concept of the tracking/sensor device, but for me it is more or less useless due to the poor range, also compared to other LoRa nodes I am testing.

I can confirm the results found by Remko; checked the internal antenna of my RAK7200 (868 MHz) with a cheap N1201SA VNA. Antenna type ZX0282-X1, resonances at 630 MHz (SWR 1:3.4), 1180 MHz (1.2) and 2250 MHz (1.5). The SWR at 868 MHz is about 1:7-8.

Are there any ideas or solutions from RAK?