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Forum Index : Microcontroller and PC projects : HC-12 legal channels (in NZ)
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| robert.rozee Guru  Joined: 31/12/2012 Location: New ZealandPosts: 2556 |
for anyone interested, attached is a PDF listing those HC-12 channels that can be legally used in New Zealand, based upon data from "Radiocommunications Regulations (General User Radio Licence for Short Range Devices) Notice 2022", see: https://gazette.govt.nz/notice/id/2022-go3100 in summary, along with channels 1, 2, 3, and 4 at any speed and up to 25mW transmitting power, you can also legally use: - channel 64 at up to 2400 baud and 100mW transmitting power, and, - channel 96 at up to 38400 baud and 100mW transmitting power. the speed limits for channel 64 and 96 are to ensure that the transmission bandwidth remains entirely within the upper and lower bounds of the respective block of spectrum. while channels 28, 29, and 93 also fall within available spectrum, their use is reserved for biomedical telemetry and thus should be avoided. HC-12 legal channel table (NZ).pdf fyi, i've been looking into this for an application involving monitoring of a sewerage system that (for compliance) requires occasional reporting of short packets of status information back to a control panel located 100m from the tanks. i wanted to put the data on a 'less commonly used' frequency to avoid annoying anyone's garage door opener! cheers, rob :-) updated PDF file to correct AI errors that slipped through for channels 28,29,93 as well as added in a table of bandwidth info associated with each of the four 'air baud rate' values. Edited 2026-11-08 02:15 by robert.rozee |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 10104 |
Yes, I use channel 64 myself at 1200 baud. Last time I looked, it was UNRESTRICTED on that band, up to 500mW. 458.600MHz No matter, cos the HC12 can't do more then 100mW max anyway. Have you ever looked at the output of an HC12 on a spectrum analyser? They're pretty good! No harmonics of any detectable level for the 1st, 2nd and 3rd. Not what you might expect from such a cheap RF module. Smoke makes things work. When the smoke gets out, it stops! |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2556 |
i probably should have noted in the PDF that apart from the one column labelled "Gazette Band Limits" all the other numeric data was from the perspective of using an HC-12, hence 100mW is mentioned as the maximum power 'achievable from an HC-12'. similarly the "Maximum Legal Air Baud" is not that calculated but instead taken from the list of rates supported by the HC-12; some of the bands could accommodate a higher rate, but the HC-12 has no means of using them. the table was produced with the assistance of Google's Gemini, although Gemini made quite a few glaring mistakes during the Q&A process that i needed to 'forcefully' point out. as always, she was very apologetic when her errors were shown. no, i don't have a spectrum analyser, but would be really interested in seeing plots for each of the nine HC-12 channels (1,2,3,4,28,29,64,93,96) tested at each of the eight possible UART baud rates  it would be useful information to include in the HC-12 manual.cheers, rob :-) |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 10104 |
I'll put that on the "To-do" pile.  Smoke makes things work. When the smoke gets out, it stops! |
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