[HH] Semtech long range device using 2.4 GHz

Kurt Keville klk at mit.edu
Mon Mar 20 08:46:41 EDT 2017


I think Semtech might be confusing the cash cow and the loss leader in
TTN logistical support. We don't need LoRa on 2.4 GHz but it would be
nice if we had (really slow) Wireless Internet options on 900 MHz. I
don't anticipate ever buying another 2.4GHz radio, seeing as you get
them for free on seemingly every board you buy these days. BLE in
particular appears to do most of what the 2.4GHz LoRa fans would like.

The low bandwidths on LoRa are a feature, not a fault. It makes us use
the network only for the appropriate functionalites.

On Sun, Mar 19, 2017 at 10:24 PM, Stephen Ronan <sronan at gmail.com> wrote:
> Those Semtech 2.4 Ghz boards support LoRa, FLRC, and (G)FSK
> modulation. Someone who knows far more than I do about these matters
> explains that the 2 Mbps data rate I had cited is via the FSK
> modulation. While for LoRa the data rate depends on the spreading
> factor (SF) about which more here:
> https://www.thethingsnetwork.org/forum/t/how-spreading-factor-influence-time-on-air/5068
> Specifically, in respect to data rates he wrote:
>
> "for LoRa 2.4Ghz it's
>
> SF 5: 202 kb/s
> SF 6: 122 kb/s
> SF 7: 71 kb/s
> SF 12: 0.476 kb/s"
>
> On Sun, Mar 19, 2017 at 5:26 PM, Stephen Ronan <sronan at gmail.com> wrote:
>> I don't know what to make of this... a new product from Semtech (which
>> owns the core LoRaWAN patent) that uses 2.4GHz spectrum... and
>> advertises a "sensitivity, down to -132 dBm". The last of the links
>> below says:  "The new 2.4 GHz wireless RF solution enables
>> point-to-point wireless links that can support custom protocols with
>> configurable data rates up to 2 Mbps". By contrast, my understanding
>> is that their LoRaWAN products max out at something like 20 kbps.
>>
>> https://www.thethingsnetwork.org/forum/t/2-4-ghz-lora/6045
>> http://www.semtech.com/apps/product.php?pn=sx1280,
>> https://www.semtech.com/wireless-rf/24ghz-wireless-rf-solution
>>
>>  - Stephen
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