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 Post subject: SX1212 Support
PostPosted: Tue Oct 01, 2013 6:08 am 

Joined: Sat Jul 13, 2013 7:27 pm
Posts: 7
What are your plans regarding SX1212 support going forward? I'd like to be able to utilize a STM32+SX1212 combination running OpenTag next, but so far have not progressed past porting it. I'd like to know your plans, and any further advice you could give me in support of this goal.

We are not planning to support SX1212 ourselves, but the community might want to support it.... but probably not, because Semtech is more interested now in SX1276. The new chips, like SPIRIT1 and SX1276, tend to use less power than SX1212 does. This is because SX1212 takes 1.5 ms to startup, and SPIRIT1 takes only ~150us to startup. DASH7 tends to do a lot of channel samples, each one takes about 300 us + startup. So, you can do the arithmetic to find that SPIRIT1 is most efficient.

We will probably start supporting SX1276 in the near future, however.

 Post subject: Re: SX1212 Support
PostPosted: Thu Jan 15, 2015 2:31 am 

Joined: Thu Jan 15, 2015 2:24 am
Posts: 1

I'm fairly inexperienced with RF devices. Is the only parameter for comparison of startup time, particularly for the SX127x vs the SPIRIT1, the time to PLL lock when coming out of standy (60us for SX)?
Have you had an opportunity to compare these two chips and determine whether one is superior for DASH7 implementation than the other?


 Post subject: Re: SX1212 Support
PostPosted: Wed Sep 02, 2015 1:53 pm 
Site Admin

Joined: Tue Jun 12, 2012 4:33 am
Posts: 25
Location: New York, NY
SPIRIT1 is much lower cost, and it is great when your range requirement is like 100-400m. It is not the most sensitive transceiver, that is the tradeoff.

LoRa devices have good sensitivity -- although Semtech's datasheet numbers are sort of bogus, not at least because they consider FEC as well as the extra demodulation gain they get from having a big, expensive LoRa base station on the other end. That said, these devices are still very sensitive, but you just can't compare the dBm figures across components (in this case) with much reliability.

Another new narrowband chip is AX5243 from Axsem. It is similar to the SPIRIT1 is most respects, but it has lower max bitrate and higher sensitivity.

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