solarwind wrote: > On Saturday, April 3, 2010, MCH wrote: > >> > > Regarding the ism band, so let's say I want to build a high altitude > weather balloon which I wan to control and communicate with using my > own equipment. Can I just build My own and use a high power ISM band > radio tranceiver? Obviously I don't want other people messing with It > so I would use encryption... > > ISM is only licence free in the sense of using PRE_APPROVED commercial equipment. You can't build your own ISM gear unless you get the appropriate FCC/CSA/CE/ETSI or whatever type approvals. EXPENSIVE There are also power limits. Much lower than for most Amateur bands. ONLY Licensed Amateurs can build and deploy their own equipment legally without getting it type approved. You don't need all out encryption actually. Repeaters and Packet Radio Nodes often have command modes that are not public. The traffic is not encrypted, but the commands to change something may need challenge / response DTMF codes. Is high power legal on US 915MHz ISM band? Here in Ireland the 433, 864 SRD bands have like 1mW continuous limit and 10mW 10% duty cycle. 446MHz PMR (like US FRS I guess) is built in aerial and 500mW. CB 27MHz approx is 1W AM and 4W FM/SSB, any external aerial as long as it's not directional (A 20dB gain directional aerial fed with 400W is legal for Amateurs on 28MHz if you had the space!). Community Radio on 27.5MHz is 1W AM and 4W FM/SSB, any external aerial as long as it's not directional and any LIVE ONLY content, but needs annual licence and only 1 agreed channel out of 80 available I think. AFAIK 2.4GHz ISM is various devices here only up to 500mW. Oddly 5.8GHz here is supposed to be WiFi only, though Analogue Video senders are in the shops. Amateur 2.3GHz is 11W. But no encryption. Technically 22dB Gain dishes on outdoor WiFi (ISM) are illegal if you feed with 500mW as that exceeds the ERP permitted. Amateurs can use whatever dish gain they can afford as the 11W is RF P.A. power, not ERP. AFAIK only 137kHz has low power, but it's specified as 0dBW = 1W ERP. With a 60ft end fed wire (20m approx) you might need 2kW of RF. The far end probably glows in the dark with 10kv to 30kv corona discharge. If you within x miles of an airbase you may need a permit for your WX balloon. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist