JethrowJohnson
Active Member
If a radio is full duplex, does that mean it can transmit and receive at the same time, or is that the same thing as TDMA? And is it possible for any computer, radio, etc. to TX/RX simultaneously (not TDMA)?
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Full Duplex / TDMA?
- Thread starter JethrowJohnson
- Start date
A radio can transmit and receive at the same time (full duplex). If it’s a mobile it will need a duplexer, if it’s a base it can with filtering (duplexer, cavities, whatever) or lots of separation between TX and RX antennas.
TDMA can simulate duplex but in actuality it’s just switching between TX and RX very fast (30 milliseconds in P25).
TDMA can simulate duplex but in actuality it’s just switching between TX and RX very fast (30 milliseconds in P25).
JethrowJohnson
Active Member
Awesome, thank you! 🙂
Project25_MASTR
Millennial Graying OBT Guy
To add to KevinC's finial comment. There are some digital modes which can simulate full duplex conversations on a half duplex platform. For example, Simoco's Xd DMR subscribers and infrastructure can support full duplex calls by allowing the subscriber radio to downlink the RX audio on one timeslot and uplink TX audio on the other timeslot. At no point is the client radio transmitting and receiving at the same time...it's just switching back and forth between RX and TX fast enough to simulate it.
JethrowJohnson
Active Member
And when a radio is duplex, if two units transmit at once, will they both be readable to the other units, or will they still cancel each other out?
@Project25_MASTR Isn't that the same as TDMA?
@Project25_MASTR Isn't that the same as TDMA?
nd5y
Member
TDMA uses time slots so the radios can't transmit at the same time, even though on some types of systems the audio path might be full duplex.
Full duplex FM, AM, FSK and most other modes can't have two transmitting signals on the same frequency at the same time or there will be interference unless at the receiving end one signal is very strong and the other is very weak. Then the weak one won't be received at all.
Full duplex FM, AM, FSK and most other modes can't have two transmitting signals on the same frequency at the same time or there will be interference unless at the receiving end one signal is very strong and the other is very weak. Then the weak one won't be received at all.
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