Hello, try the words "packet radio" in alta vista, i think you will get quite some hits.. This technic is used to transfer data on transceivers, the protocol is called Ax.25 (amateur X.25) protocol, the normal x25 protocol is a network based one, this ax25 developed by radio amateurs to transmit data over radio. The modem you need for this is very simple to build "baycom" -modem for instance, and software is also available for any operating system win9X and linux. http://cybersake.www.cistron.nl/baycom.htm Good luck! Aart. ----- Original Message ----- From: "Francois Robbertze" To: Sent: Tuesday, February 13, 2001 2:52 PM Subject: Re: [PIC]: RF Tranceivers w/PIC (16F84/16F877) > Dear David Huisman > > Just a dumb question! > > I know that some telemetrie systems use normal two way radios... > > How do you connect a pic to a two way radio? Do you need a interface between > the analog input (microphone) of the radio and the pic(Tx) and again from > the speaker to the pic(Rx). > > Are there dedicated IC to do these work. I heard ones that there are IC's > that do error correction etc. so you don't have to worry about that in the > pic and they do the data transmission for you. Can someone help me with a > manufacturer... > > Are the connection to the pic different when using a 'data" transceiver > > Regards > > Francois > > ----- Original Message ----- > From: David Huisman > To: > Sent: Tuesday, February 13, 2001 12:07 AM > Subject: Re: [PIC]: RF Tranceivers w/PIC (16F84/16F877) > > > > Mik, > > > > Usually when you talk "long distance" (say greater than a couple of km), > the > > devices require higher power. > > > > The power required usually exceeds the allowable maximum for the > unlicensed > > band. > > > > Now the unit has to be licensed, it also has to be subject to testing to > the > > standards for the frequency band you have chosen to operate within. > > The standards are far more stringent than those for unlicensed. > > > > This means the design process is far more extensive, the component costs > are > > more expensive (due to having to meet all the additional specs). > > The investment costs are higher as someone has to pay for the local > testing > > body to test the device type (Type Approval) to the standard and issue a > > certificate of compliance. > > > > And guess where these costs are recovered ... that's right ! in the price > of > > the unit. > > > > Even for unlicensed equipment, the performance (and range) differ > > dramatically. > > There are many "garage door opener" technology based solutions that may be > > good for 100-200m but you must look carefully at the specifications. > > The stated range for lower cost units is quite often the Free-Space, Line > of > > sight best case (i.e.. if the two units were lifted 1.5m in the air in an > > empty field, then on a good day, the unit 100m away will receive the > > transmission). > > > > When comparing performance of radio modules. Look at the defined BER (Bit > > Error Rate) and Sensitivity. > > > > A radio with BER of 1e-3 at a sensitivity of -110 dBm would be great. But > a > > unit with BER of 1e-2 at -90dBm would not be so hot. > > Note: BER of 1e-3 means that if you transmit 1000 bits of information, > > statistically there would be 1 error. > > > > Our preferred solution is an RF module with controller board .. As > explained > > on our site page http://www.orbitcoms.com/rf_modules.htm > > > > If you look at http://www.orbitcoms.com/rf_module_intro.htm , I discuss > some > > of the issues. > > > > Regards > > > > David Huisman > > > > -- > > http://www.piclist.com hint: The list server can filter out subtopics > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.