Does the HT-M01 LoRa concentrator support fine-timestamps?


#1

Dear everyone,

I have some questions about how to locate lora-device. I observed the launch of the lora-geo-server service. If I can successfully locate the location of the node device, the help of Influxdb and Grafana for IoT visualization is very large.

I refer to Requirements: “When using geolocation, you need a gateway which provides geolocation capabilities. These gateways provide accurate timestamps, which is a requirement when doing geolocation based on time-difference of arrival"and"Gateways implementing the Semtech v2 Reference design will encrypt the fine-timestamp.”

In other words, you must meet two conditions to implement the geolocation function:
1. The gateway provides precise time stamping to support the TDoA algorithm;
2. The gateway must have geolocation capabilities.

So now I have a few questions:
1. How can I know if this gateway (HT-M01) is based on Semtech v2, can it provide precise time stamping?
2. If the gateway is indeed based on Semtech v2, should I ask Semtech for the timestamp’s decryption key?
3. Unfortunately, after I asked the manufacturer of “HT-M01”, they replied to me “HT-M01 does not have a GPS module”. After that I accidentally found that I can manually set the gateway geography in lora-app-server. Positioning, and in the “uplink” that follows, the value of location is changed with my setting value. Is it equivalent to the gateway having the positioning function to support the TDoA algorithm when I manually set the geolocation of the gateway in the app-server?

Even a little bit, thank you for answering me.


#2
  1. How can I know if this gateway (HT-M01) is based on Semtech v2, can it provide precise time stamping?

In general, ask your vendor but given it is a ~ $100 shield / module I can already tell you it probably does not provide accurate RX timestamp (e.g. like the Kerlink iBTS gateways).

  1. If the gateway is indeed based on Semtech v2, should I ask Semtech for the timestamp’s decryption key?

Correct.

  1. Unfortunately, after I asked the manufacturer of “HT-M01”, they replied to me “HT-M01 does not have a GPS module”. After that I accidentally found that I can manually set the gateway geography in lora-app-server.

The GPS / GNSS is not only for the location, but also for accurate time synchronization.


#3

Heltec HT-M01 is a pico-gw. of course it doesn’t support fine timestampings.

Recently Semtech changed mind and they will provide LoRa geolocation decryption keys for free and make Collos for free maintaining a pro/paid service as well.


#4

Thanks both for answering me.

I think if I can use the external GPS module to meet the conditions for starting the Lora-geo-server? In other words, you get the finetimestamp.
The GPS module I use is ublox-7.
According to this idea, I can see that the GPS module is enabled in the log of the packet_forwarder.

### [GPS] ###
# Valid time reference (age: 1542683015 sec)
# GPS coordinates: latitude 30.69496, longitude 104.17529, altitude 535 m
##### END #####

But I observed “fineTimestampType”: “NONE” in the uplink.

How can I get fineTimestamp? Or how do you import “fineTimestamp” from the GPS module?
Thank you


#5

You need a Semtech v2 gateway.

It is not as easy as connect a GPS module to a Semtech v1 or pico gateway. The fine-timestamp is processed in the FPGA included in Semtech v2.


#6

Have you tried this yourself, to obtain the decryption keys for a v2 gateway?

I am a bit lost on what it actually means in Semtechs announcement:

“Semtech will open access to high-resolution timestamps and will include this in future licensed firmware versions of our gateway reference designs. Given the volume of existing LoRa-enabled gateways already deployed across the world, Semtech will also provide decryption keys for existing gateways to enable gateway owners to decrypt the timestamps either within the gateway itself or the network.”

What is means by censed firmware versions? Is this just LoRaWAN? Does this mean LoRaWAN supports high precision time stamps?


#7

I have no experience on that.

as far as i see, semtech did not release any FPGA firmware update in two years.