What is a Linear Satellite in Ham Radio?

What is a Linear Satellite in Ham Radio?

FM satellites are like orbiting repeaters which pass overhead several times a day and Ham Radio operators can communicate through them using dual band hand held transceivers. But as only one person can access it at a time, there could be difficulty during peak usage times like on weekends. Unlike the single channel FM satellites, linear satellites use SSB and CW and have a transponder which can provide a bandwidth of 20 to 50 KHz. Hence it is possible for multiple operators to use the linear satellites simultaneously. It is somewhat similar to the WebSDRs in which multiple users can simultaneously tune different frequencies. The operation of Qatar Oscar 100 Geostationary Amateur Radio Satellite is also similar.

An important requirement when you plan to work linear satellites is the ability to simultaneously transmit and receive on VHF and UHF amateur bands. This has been called as full duplex operation. One should be able to listen one’s own signal on the downlink frequency through out the entire pass of the satellite before the contact is made. Some use two radios for this purpose when one radio does not have a full duplex function. A duplexer is needed to isolate the transmitted signal from the receiver to prevent overloading of the receiver during transmission with simultaneous reception, which does not occur in your usual radios.