The 2015 LIPD (Low Interference Potential Devices) Class Licence for
Australia lists under the section for 'Transmitters for non-specific applications' and 'Frequency hopping, WiFi and RLAN transmitters':
Transmitters for non-specific applications
Item From To Power Comments
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19 433.05 - 434.79 25mW All transmitters
20 915 – 928 3mW All transmitters
Frequency hopping, WiFi and RLAN transmitters
Item From To Power Comments
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54 915 - 928 1W A minimum of 20 hopping frequencies must be used
55 2400 - 2483.5 500mW A minimum of 15 hopping frequencies must be used
56 2400 - 2483.5 4W A minimum of 75 hopping frequencies must be used
57 5725 - 5850 4W A minimum of 75 hopping frequencies must be used
58 915 - 928 1W | Digital modulation transmitters (e.g. OFDM). The radiated peak
59 2400 - 2483.5 4W | power spectral density in any 3 kHz must not exceed 25 mW per
60 5725 - 5850 4W | 3 kHz. The minimum 6 dB bandwidth must be at least 500 kHz.
Source: Radiocommunications (Low Interference Potential Devices) Class Licence 2015, pages 9, 17 and 18ACMA link to the LIPD class licence page:
https://www.legislation.gov.au/Details/F2015L01438The output power is stated as EIRP and is the power
coming out of the antenna.
These bands are what most people refer to as the ISM (Industrial Scientific and Medical) bands; you don't need to obtain an official transmitter licence (as long as you stay within the regulations) but also can't expect to be free from interference from other devices. With ISM it will also be difficult to legally defend your position that you are entitled to unobstructed use of these frequencies. A sort of 'First come first served' applies.
Item(s) 55, 56, 57, 59 and 60 may not be of immediate use to everyone but it shows what else is available in common 2.4GHz and 5.8GHz bands.
For the RFM69 and friends the 433MHz and 915MHz items apply (items 19, 20, 54 and 58). Therefore, of the available frequencies for the RFM69/12 modules (433/868/915) only the 433MHz and 915MHz modules may be legally used in Australia.
The modulation type that the RFM69/12 modules use is FSK (Frequency Shift Keying) and is considered 'Digital Modulation'. Therefore under item 58 (using 915MHz) a total power of 1W (30dBm) EIRP is the maximum allowed. In practical terms, a 100mW (20dBm) transmitter may be connected to an antenna with 10dB gain (e.g. 6-element Yagi) and still be within the licence conditions.
What I am unable to verify is the exact specification of the RFM69/12 915MHz modules and their spectral density and bandwidth. If for whatever reason these devices do not comply with the regulations of Item 58 then instead Item 20 applies and the total power out of the antenna must not exceed 3mW. If you cannot regulate the power output of the device through software registers to be that low then an in-line attenuator can be used.
Using the radio's in the ISM band for 433MHz (Item 19) may 'only' allow you to use 25mW but this can be enough for short distance comms (maybe around 20 meters line of sight or so). Also remember that lower frequencies have a higher level of penetration through building structures and vegetation.
For those that have their Australian Amateur Radio Licence, 433MHz may be of more interest as it will allow you up to 30W of output power
from the transmitter on that band. Also, there is no Amateur Radio band on 915MHz so the limit is 1W in any case.
Disclaimer: I am not a lawyer, use and interpret at own risk, etc..