I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
Mike,
It depends on the transceiver that you have. Essentially the up link and down link are using different bands, U and V for example. If you transmit on a V uplink your transmission is transmitted back on the downlink on a U frequency. If your transceiver is capable of duplex operation, you can hear your own transmission on the downlink with a delay that depends on the sat distance from your location. with today's leo sats, it is hardly noticeable. The duplex in the sat communications means that you can transmit and receive simultaneously.
Hope that that clarify.
David, 4X1DG ----- Original Message ----- From: Mike To: [email protected] Sent: Wednesday, July 27, 2011 3:25 PM Subject: [amsat-bb] Full Duplex?
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
It is just like a telephone conversation. With little or no delay, however back in the days of AO-40 (sobsob), when it was way out there, the delay was very noticeable and listening to ones self you got a bit stuttering.
73 Bob W7LRD
----- Original Message -----
From: "David 4X1DG" [email protected] To: "Mike" [email protected], [email protected] Sent: Wednesday, July 27, 2011 5:51:26 AM Subject: [amsat-bb] Re: Full Duplex?
Mike,
It depends on the transceiver that you have. Essentially the up link and down link are using different bands, U and V for example. If you transmit on a V uplink your transmission is transmitted back on the downlink on a U frequency. If your transceiver is capable of duplex operation, you can hear your own transmission on the downlink with a delay that depends on the sat distance from your location. with today's leo sats, it is hardly noticeable. The duplex in the sat communications means that you can transmit and receive simultaneously.
Hope that that clarify.
David, 4X1DG ----- Original Message ----- From: Mike To: [email protected] Sent: Wednesday, July 27, 2011 3:25 PM Subject: [amsat-bb] Full Duplex?
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Mike.
Full duplex is where you can receive the signal from the satellite at the same time as you are transmitting up to it.
It allows you to hear your own signal through the satellites transponder. So you know if your signal made it, or if it was submerged under someone else who was transmitting at the same time.
Full duplex radios are the exception, but well worth having.
Another method is to use 2 simlex radios to get the same result.
David G0MRF
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
=
Hi Mike,
Full duplex is pretty simple: Listening to the downlink (receive) while *simultaneously* transmitting on the uplink. This enables you to hear you transmission WHILE YOU ARE TRANSMITTING - at the same time.
There are a lot of benefits behind operating this way, the main one being reducing QRM to other stations and maximizing operating time.
Does that answer your question?
73,
Zack KD8KSN
-----Original Message----- From: Mike Sent: Wednesday, July 27, 2011 8:25 AM To: [email protected] Subject: [amsat-bb] Full Duplex?
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
_______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
A link is FULL DUPLEX if you and the other station are both receiving and transmitting simultaneously. It is HALF DUPLEX if you can both receive and transmit but NOT simultaneously (as on your local FM repeater or a packet satellite link). It is SIMPLEX if you can receive OR transmit but not both (as in a telemetry transmission).
On 07/27/2011 01:25 PM, Mike wrote:
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Mike,
Others have answered the question quite well. One additional point I'd like to make is how important it is to actually listen to your yourself on the downlink, for a couple reasons.
1. On an FM bird, if you can't hear yourself or you hear a double... Stop transmitting 2. On a linear transponder (CW, SSB), use only enough uplink transmit power to be heard on the downlink.
For #2, the rule of thumb is to compare your downlink signal strength to that of the satellite's beacon and adjust your uplink power so your downlink does not exceed that. A satellite PA can only put out so much power (say 1W). So if your uplink is 20 dB stronger at the satellite than anyone else's, your downlink could be transmitted at .99W leaving only 10mW for the rest of the QSO's in the passband.
73
John Belstner W9EN Valley Center, CA DM13le
----- Original Message ----
From: Mike [email protected] To: [email protected] Sent: Wed, July 27, 2011 5:25:49 AM Subject: [amsat-bb] Full Duplex?
I'm having a difficult time of understanding the concept of Full Duplex. Can anyone explain it to me? I have the ARRL satellite book, read about it in there and Wikipedia. I still didn't understand how it works with a transceiver setup like we use.
Mike N8GBU
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (7)
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Bob- W7LRD -
David 4X1DG -
g0mrf＠aol.com -
John M. Belstner -
Mike -
Nigel A. Gunn, W8IFF/G8IFF -
Zachary Beougher