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LoRa USA Frequency?

Michael Sharp
 

Hello,
I noticed that the Morserino-32 that I have has LoRa frequency for Europe (433Mhz). For USA, this should be somewhere around 908 - 928 MHz.

Will simply changing these lines in code correct the frequency for the transmitter?

(Starting at Line 1147)
  LoRa.setFrequency(434.15E6);                     /// f = 434.150 MHz - Region 1 ISM Band
  LoRa.setSpreadingFactor(7);                      /// default
  LoRa.setSignalBandwidth(250E3);                  /// 250 kHz
  LoRa.noCrc();                                    /// we use error correction
  LoRa.setSyncWord(0x27);                          /// the default would be 0x34

Willi, OE1WKL
 

No, the LoRa module included in the Heltec Module only supports 433 MHz (main reason is that you need different output filters). This means only in Region 1 (Europe, Africa, ME) you can use the LoRa Trx function without a ham radio license. In other parts of the world you can use it as a ham radio operator as it is in the 70 cm band (although it might not be conformant to the IARU band plan of regions 2 an 3).



Am 17.06.2019 um 23:53 schrieb Michael Sharp via Groups.Io <nexxusix@...>:

Hello,
I noticed that the Morserino-32 that I have has LoRa frequency for Europe (433Mhz). For USA, this should be somewhere around 908 - 928 MHz.

Will simply changing these lines in code correct the frequency for the transmitter?

(Starting at Line 1147)
  LoRa.setFrequency(434.15E6);                     /// f = 434.150 MHz - Region 1 ISM Band
  LoRa.setSpreadingFactor(7);                      /// default
  LoRa.setSignalBandwidth(250E3);                  /// 250 kHz
  LoRa.noCrc();                                    /// we use error correction
  LoRa.setSyncWord(0x27);                          /// the default would be 0x34

Dan
 

One follow up on this.  Could the frequency be shifted slightly in firmware by changing that value?  Something just move it to a more favorable part of the US 70 cm band to comply with the band plan.  Maybe somewhere in the 432.070 - 432.300 range?  Is the transmitted signal a normal CW signal or is it digital or something like that.  Just curious if there is a way to legally use that feature in the US.

Thanks,
Dan KF5CSO

Willi, OE1WKL
 

Hi Dan,

Providing several frequencies within the 70cm band is certainly an option - I put that on my to do list.
Re the type of signal: this uses LoRa, which is a low power spread spectrum modulation, mainly used for Intern of Things applications. So this is not A1 (keyed carrier). Because LoRa is a data transmission protocol, I designed a special protocol to encode Morse Code data into these data packets, which will be sent out as short bursts whenever you reach a word pause. It does NOT send the characters as ASCII characters: it really encodes dots, dashes and pauses, so even invalid characters (or alien character sets, like Japanese Morse Code characters) are being transmitted faithfully.

73

Willi


Am 27.06.2019 um 17:10 schrieb Dan <dv1900@...>:

One follow up on this.  Could the frequency be shifted slightly in firmware by changing that value?  Something just move it to a more favorable part of the US 70 cm band to comply with the band plan.  Maybe somewhere in the 432.070 - 432.300 range?  Is the transmitted signal a normal CW signal or is it digital or something like that.  Just curious if there is a way to legally use that feature in the US.

Thanks,
Dan KF5CSO

Greg - WB5GM
 

Just wanted to comment that the LoRA does not transmit CW, but something akin to "packets" which are encoded on Tx and decoded on Rx.  See pg. 11 of the manual.  I have viewed that transmission with my SDR-RTL and it's just a periodic 'splash' of RF on the monitor.

Greetings Willi - I love the Morserino.  In just a few weeks, I have progressed with CW training and almost ready for my first QSO. (May need FLdigi to help me copy....)

73

Willi, OE1WKL
 

I agree, Greg. Therefore the range up to 432.300 MHz is not suitable, as this is reserved for low bandwidth modes like A1, A3j and narrow band digital modes. As LoRa is Wideband, it should reside somewhere where Wideband is tolerated.
I actually think that it coexists quite nicely with FM - your transceiver will not come out of squelch even with a LoRa Transceiver in its vicinity, and LoRa is not really easily disturbed by modes that are much narrower than it is itself.
Now I cannot tell anything about other legalities (e.g. sending out your call sign: can this be encapsulated into some data codec, if the protocol has been published?).

BTW, I was only successful in detecting a LoRa transmission with a professional direction finding receiver by R6S, worth > 20.000 US$ - there you see the emissions as short blips on their spectrum scope. With amateur receivers I was not successful - neither in FM, AM or CW/SSB.

73

Willi
OE1WKL


Am 28.06.2019 um 14:36 schrieb Greg - WB5GM <greg@...>:

Just wanted to comment that the LoRA does not transmit CW, but something akin to "packets" which are encoded on Tx and decoded on Rx.  See pg. 11 of the manual.  I have viewed that transmission with my SDR-RTL and it's just a periodic 'splash' of RF on the monitor.

Greetings Willi - I love the Morserino.  In just a few weeks, I have progressed with CW training and almost ready for my first QSO. (May need FLdigi to help me copy....)

73

Dan
 

Thanks for the replies, all.  I really appreciate the info.  I just ordered the kit, and so I've been thinking about it a little as I wait for it to arrive.  It sounds like I should be good to use it in the 70 cm band.  It's low power, and doesn't look like it's encrypted or anything, so I think it would be well within my license privileges to use it.  It would definitely be nice if it were in a friendly part of the band, but from you said, Willi, it isn't likely to cause any interference anyway.  

Thanks!
Dan - KF5CSO

taz96ci71@...
 

Would using the Heltec V2 915 MHz module to replace the module shipped be a nearly drop in solution to using the region 2 ISM frequency? I sure there would have to be some code adjustment. But would it work?

Willi, OE1WKL
 

Yes, this certainly should work. Code adjustment will be necessary. I will put this on my to do list.
Already got two modules with that frequency for testing.
This will happen after my vacation….

73
Willi

Am 01.07.2019 um 19:59 schrieb taz96ci71 via Groups.Io <taz96ci71@...>:

Would using the Heltec V2 915 MHz module to replace the module shipped be a nearly drop in solution to using the region 2 ISM frequency? I sure there would have to be some code adjustment. But would it work?