Andrey Sviyazov, this question is probably for you,
IIRC, both nanoBTS and SysmoBTS have separate antennas for Rx andTx and do not use duplexers. Do we need duplexer for UmTRXv2 if it operates in the low power mode, without an additional PA/LNA?
-- Regards, Alexander Chemeris CEO, Fairwaves LLC http://fairwaves.ru
Hi Alexander.
If Tx level very small and Rx path not saturated, than you should check Rx noise flour to be sure that TX doesn't jumm Rx. Anyway it all about Rx sensitivity only.
Best regards, Andrey Sviyazov. (Sent from my mobile client) 11.10.2012 1:07 пользователь "Alexander Chemeris" < alexander.chemeris@gmail.com> написал:
Andrey Sviyazov, this question is probably for you,
IIRC, both nanoBTS and SysmoBTS have separate antennas for Rx andTx and do not use duplexers. Do we need duplexer for UmTRXv2 if it operates in the low power mode, without an additional PA/LNA?
-- Regards, Alexander Chemeris CEO, Fairwaves LLC http://fairwaves.ru
Hi,
IIRC, both nanoBTS and SysmoBTS have separate antennas for Rx andTx and do not use duplexers. Do we need duplexer for UmTRXv2 if it operates in the low power mode, without an additional PA/LNA?
Note that both still have internal filters.
Antenna design also plays a role. The nanoBTS uses patch antenna separated by a lump of metal to minimize direct radiation from TX to RX.
Cheers,
Sylvain
On Thu, Oct 11, 2012 at 9:58 AM, Sylvain Munaut 246tnt@gmail.com wrote:
Hi,
IIRC, both nanoBTS and SysmoBTS have separate antennas for Rx andTx and do not use duplexers. Do we need duplexer for UmTRXv2 if it operates in the low power mode, without an additional PA/LNA?
Note that both still have internal filters.
You mean bandpass filters? Are they only on Rx side or both Tx and Rx?
Antenna design also plays a role. The nanoBTS uses patch antenna separated by a lump of metal to minimize direct radiation from TX to RX.
Yes, I remember that nanoBTS has patch antennas for better isolation. But IIRC sysmoBTS has rubber duck antennas which made me wonder how do they do Tx/Rx isolation.
Hi,
You mean bandpass filters? Are they only on Rx side or both Tx and Rx?
Yes, bandpass filters. (SAW or Ceramic, possibly both)
nanoBTS has both side. You can clearly see them here : http://openbsc.osmocom.org/trac/wiki/nanoBTS/Internals sysmoBTS I know has RX filters, I don't remember about TX.
Yes, I remember that nanoBTS has patch antennas for better isolation. But IIRC sysmoBTS has rubber duck antennas which made me wonder how do they do Tx/Rx isolation.
Mine actually shipped without antennas :p
I use it with rubber duck in lab tests but I don't know if it's a recommended configuration.
Cheers,
Sylvain
On Thu, Oct 11, 2012 at 3:01 PM, Sylvain Munaut 246tnt@gmail.com wrote:
You mean bandpass filters? Are they only on Rx side or both Tx and Rx?
Yes, bandpass filters. (SAW or Ceramic, possibly both)
nanoBTS has both side. You can clearly see them here : http://openbsc.osmocom.org/trac/wiki/nanoBTS/Internals sysmoBTS I know has RX filters, I don't remember about TX.
Hum, I don't see how is that different from a duplexer if they have both Rx and Tx filters. Do you know any particular reason for this design?
Hi,
nanoBTS has both side. You can clearly see them here : http://openbsc.osmocom.org/trac/wiki/nanoBTS/Internals sysmoBTS I know has RX filters, I don't remember about TX.
Hum, I don't see how is that different from a duplexer if they have both Rx and Tx filters. Do you know any particular reason for this design?
It still exposes independent TX and RX lines allowing for external amplification / filtering if required.
Also in a duplexer you have a direct electrical connection rather than TX->RX radiation which means you need much more attenuation (often requiring the duplexer + subsequent band pass filters).
Cheers,
Sylvain
-
Alexander Chemeris -
Andrey Sviyazov -
Sylvain Munaut