Empathy List Archives

JS

Jan Safar

Wed, Mar 2, 2016 10:19 AM

Hello,

We are looking to use the E310 for some over-the-air tests in the VHF band. In our application we need to install our antennas within a few meters (say 3 to 5 m) of another VHF system antenna. The transmitter power of the co-located unit can be up to 25 W, antennas for both systems are typically 0 dBd omnidirectional. The interfering transmissions are intermittent and can be as close as on the adjacent channel. The stated maximum input power for all USRPs is -15 dBm; for the E310 and at VHF, the limit is probably somewhat higher but Ettus haven't been able to provide an exact figure.

I'm wondering if anyone can advise on how to protect the USRP input in this scenario?

I looked into the availability of suitable limiters. Mini Circuits don't seem to have any with output power below 0 dBm. I found the following two models from Herotek and RF-LAMBDA which limit at -10 dBm, but they are quite costly (~£600 excl. VAT) and the lead time is 6 to 10 weeks. Does anyone know of a better solution?

http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf
http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf

Thanks & regards,
Jan

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Hello, We are looking to use the E310 for some over-the-air tests in the VHF band. In our application we need to install our antennas within a few meters (say 3 to 5 m) of another VHF system antenna. The transmitter power of the co-located unit can be up to 25 W, antennas for both systems are typically 0 dBd omnidirectional. The interfering transmissions are intermittent and can be as close as on the adjacent channel. The stated maximum input power for all USRPs is -15 dBm; for the E310 and at VHF, the limit is probably somewhat higher but Ettus haven't been able to provide an exact figure. I'm wondering if anyone can advise on how to protect the USRP input in this scenario? I looked into the availability of suitable limiters. Mini Circuits don't seem to have any with output power below 0 dBm. I found the following two models from Herotek and RF-LAMBDA which limit at -10 dBm, but they are quite costly (~£600 excl. VAT) and the lead time is 6 to 10 weeks. Does anyone know of a better solution? http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf Thanks & regards, Jan ********************************************************************** This e-mail has been scanned for all viruses on behalf of Trinity House by the Symantec.Cloud Anti-virus Service. This communication, together with any files or attachments transmitted with it contains information which is confidential and may be subject to legal privilege and is intended solely for the use by the person(s) or entity to whom it is addressed. If you are not the intended recipient you must not copy, distribute, publish or take any action in reliance on it. If you have received this communication in error, please notify postmaster@thls.org and delete it from your computer systems. Trinity House reserves the right to monitor all communications for lawful purposes. Receipt of this email does not imply consent to use or provide this email address, or any others contained therein, to any third party for any purposes. The contents of this email are protected under international copyright law. To save energy and paper please print this email only if you really need to. This email originated from: "The Corporation of Trinity House of Deptford Strond" which is incorporated by Royal Charter in England and Wales. The Royal Charter number is RC 000622. The Registered office is Trinity House, Tower Hill, London, EC3N 4DH. Website: http://www.trinityhouse.co.uk **********************************************************************

MD

Marcus D. Leech

Wed, Mar 2, 2016 4:12 PM

On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote:

Hello,

We are looking to use the E310 for some over-the-air tests in the VHF
band. In our application we need to install our antennas within a few
meters (say 3 to 5 m) of another VHF system antenna. The transmitter
power of the co-located unit can be up to 25 W, antennas for both
systems are typically 0 dBd omnidirectional. The interfering
transmissions are intermittent and can be as close as on the adjacent
channel. The stated maximum input power for all USRPs is -15 dBm; for
the E310 and at VHF, the limit is probably somewhat higher but Ettus
haven’t been able to provide an exact figure.

I’m wondering if anyone can advise on how to protect the USRP input in
this scenario?

I looked into the availability of suitable limiters. Mini Circuits
don’t seem to have any with output power below 0 dBm. I found the
following two models from Herotek and RF-LAMBDA which limit at -10
dBm, but they are quite costly (~£600 excl. VAT) and the lead time is
6 to 10 weeks. Does anyone know of a better solution?

http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf

http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf

Thanks & regards,

Jan

You could install a notch filter for the other VHF frequency that is
most likely to cause you issues.

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third party for any purposes. The contents of this email are protected
under international copyright law.

To save energy and paper please print this email only if you really
need to.

This email originated from: "The Corporation of Trinity House of
Deptford Strond" which is incorporated by Royal Charter in England and
Wales. The Royal Charter number is RC 000622. The Registered office is
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USRP-users mailing list
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http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote: > > Hello, > > We are looking to use the E310 for some over-the-air tests in the VHF > band. In our application we need to install our antennas within a few > meters (say 3 to 5 m) of another VHF system antenna. The transmitter > power of the co-located unit can be up to 25 W, antennas for both > systems are typically 0 dBd omnidirectional. The interfering > transmissions are intermittent and can be as close as on the adjacent > channel. The stated maximum input power for all USRPs is -15 dBm; for > the E310 and at VHF, the limit is probably somewhat higher but Ettus > haven’t been able to provide an exact figure. > > I’m wondering if anyone can advise on how to protect the USRP input in > this scenario? > > I looked into the availability of suitable limiters. Mini Circuits > don’t seem to have any with output power below 0 dBm. I found the > following two models from Herotek and RF-LAMBDA which limit at -10 > dBm, but they are quite costly (~£600 excl. VAT) and the lead time is > 6 to 10 weeks. Does anyone know of a better solution? > > http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf > > http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf > > Thanks & regards, > > Jan > You could install a notch filter for the other VHF frequency that is most likely to cause you issues. > ********************************************************************** > This e-mail has been scanned for all viruses on behalf of Trinity > House by the Symantec.Cloud Anti-virus Service. > > This communication, together with any files or attachments transmitted > with it contains information which is confidential and may be subject > to legal privilege and is intended solely for the use by the person(s) > or entity to whom it is addressed. If you are not the intended > recipient you must not copy, distribute, publish or take any action in > reliance on it. If you have received this communication in error, > please notify postmaster@thls.org and delete it from your computer > systems. > > Trinity House reserves the right to monitor all communications for > lawful purposes. Receipt of this email does not imply consent to use > or provide this email address, or any others contained therein, to any > third party for any purposes. The contents of this email are protected > under international copyright law. > > *To save energy and paper please print this email only if you really > need to.* > > This email originated from: "The Corporation of Trinity House of > Deptford Strond" which is incorporated by Royal Charter in England and > Wales. The Royal Charter number is RC 000622. The Registered office is > Trinity House, Tower Hill, London, EC3N 4DH. Website: > http://www.trinityhouse.co.uk > > ********************************************************************* > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

JS

Jan Safar

Thu, Mar 3, 2016 9:37 AM

Hi Marcus,

Thank you for your reply. Unfortunately a notch filter does not seem to be a practical proposition for our application. There are normally more than one frequency that could cause problems and different frequencies may be in use at different locations (our terminals are mobile).

Jan

From: USRP-users [mailto:usrp-users-bounces@lists.ettus.com] On Behalf Of Marcus D. Leech via USRP-users
Sent: 02 March 2016 16:12
To: usrp-users@lists.ettus.com
Subject: Re: [USRP-users] USRP Input Protection

On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote:
Hello,

We are looking to use the E310 for some over-the-air tests in the VHF band. In our application we need to install our antennas within a few meters (say 3 to 5 m) of another VHF system antenna. The transmitter power of the co-located unit can be up to 25 W, antennas for both systems are typically 0 dBd omnidirectional. The interfering transmissions are intermittent and can be as close as on the adjacent channel. The stated maximum input power for all USRPs is -15 dBm; for the E310 and at VHF, the limit is probably somewhat higher but Ettus haven't been able to provide an exact figure.

I'm wondering if anyone can advise on how to protect the USRP input in this scenario?

I looked into the availability of suitable limiters. Mini Circuits don't seem to have any with output power below 0 dBm. I found the following two models from Herotek and RF-LAMBDA which limit at -10 dBm, but they are quite costly (~£600 excl. VAT) and the lead time is 6 to 10 weeks. Does anyone know of a better solution?

http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf
http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf

Thanks & regards,
Jan
You could install a notch filter for the other VHF frequency that is most likely to cause you issues.

This e-mail has been scanned for all viruses on behalf of Trinity House by the Symantec.Cloud Anti-virus Service.

This communication, together with any files or attachments transmitted with it contains information which is confidential and may be subject to legal privilege and is intended solely for the use by the person(s) or entity to whom it is addressed. If you are not the intended recipient you must not copy, distribute, publish or take any action in reliance on it. If you have received this communication in error, please notify postmaster@thls.org mailto:postmaster@thls.org and delete it from your computer systems.

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Hi Marcus, Thank you for your reply. Unfortunately a notch filter does not seem to be a practical proposition for our application. There are normally more than one frequency that could cause problems and different frequencies may be in use at different locations (our terminals are mobile). Jan From: USRP-users [mailto:usrp-users-bounces@lists.ettus.com] On Behalf Of Marcus D. Leech via USRP-users Sent: 02 March 2016 16:12 To: usrp-users@lists.ettus.com Subject: Re: [USRP-users] USRP Input Protection On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote: Hello, We are looking to use the E310 for some over-the-air tests in the VHF band. In our application we need to install our antennas within a few meters (say 3 to 5 m) of another VHF system antenna. The transmitter power of the co-located unit can be up to 25 W, antennas for both systems are typically 0 dBd omnidirectional. The interfering transmissions are intermittent and can be as close as on the adjacent channel. The stated maximum input power for all USRPs is -15 dBm; for the E310 and at VHF, the limit is probably somewhat higher but Ettus haven't been able to provide an exact figure. I'm wondering if anyone can advise on how to protect the USRP input in this scenario? I looked into the availability of suitable limiters. Mini Circuits don't seem to have any with output power below 0 dBm. I found the following two models from Herotek and RF-LAMBDA which limit at -10 dBm, but they are quite costly (~£600 excl. VAT) and the lead time is 6 to 10 weeks. Does anyone know of a better solution? http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf Thanks & regards, Jan You could install a notch filter for the other VHF frequency that is most likely to cause you issues. ********************************************************************** This e-mail has been scanned for all viruses on behalf of Trinity House by the Symantec.Cloud Anti-virus Service. This communication, together with any files or attachments transmitted with it contains information which is confidential and may be subject to legal privilege and is intended solely for the use by the person(s) or entity to whom it is addressed. If you are not the intended recipient you must not copy, distribute, publish or take any action in reliance on it. If you have received this communication in error, please notify postmaster@thls.org<mailto:postmaster@thls.org> and delete it from your computer systems. Trinity House reserves the right to monitor all communications for lawful purposes. Receipt of this email does not imply consent to use or provide this email address, or any others contained therein, to any third party for any purposes. The contents of this email are protected under international copyright law. To save energy and paper please print this email only if you really need to. This email originated from: "The Corporation of Trinity House of Deptford Strond" which is incorporated by Royal Charter in England and Wales. The Royal Charter number is RC 000622. The Registered office is Trinity House, Tower Hill, London, EC3N 4DH. Website: http://www.trinityhouse.co.uk ********************************************************************* _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com<mailto:USRP-users@lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

MM

Marcus Müller

Thu, Mar 3, 2016 12:40 PM

Dear Jan,

Well, in that case, a bandpass that only lets through your signal of
interest surely sounds the most "high quality" solution, but it would
limit your flexibility, as you would have to change that filter
depending on what frequency you want to receive.

Protection diodes for high bandwidths / Gigahertz frequencies and low
powers are inherently hard to get -- low powers imply thin semiconductor
interfaces, thin semiconductor interfaces imply small separation between
positive and negative charges, which implies high capacitance, which
implies low-pass characteristics if inserted between signal line and ground.

This quickly boils down to a matter of money: Of course you could "just"
use attenuators and a properly cooled LNA close to the antenna...

Best regards,
Marcus

On 03/03/2016 10:37 AM, Jan Safar via USRP-users wrote:

Hi Marcus,

Thank you for your reply. Unfortunately a notch filter does not seem
to be a practical proposition for our application. There are normally
more than one frequency that could cause problems and different
frequencies may be in use at different locations (our terminals are
mobile).

Jan

*From:*USRP-users [mailto:usrp-users-bounces@lists.ettus.com] *On
Behalf Of *Marcus D. Leech via USRP-users
Sent: 02 March 2016 16:12
To: usrp-users@lists.ettus.com
Subject: Re: [USRP-users] USRP Input Protection

On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote:

 Hello,

  

 We are looking to use the E310 for some over-the-air tests in the
 VHF band. In our application we need to install our antennas
 within a few meters (say 3 to 5 m) of another VHF system antenna.
 The transmitter power of the co-located unit can be up to 25 W,
 antennas for both systems are typically 0 dBd omnidirectional. The
 interfering transmissions are intermittent and can be as close as
 on the adjacent channel. The stated maximum input power for all
 USRPs is -15 dBm; for the E310 and at VHF, the limit is probably
 somewhat higher but Ettus haven’t been able to provide an exact
 figure.

  

 I’m wondering if anyone can advise on how to protect the USRP
 input in this scenario?

  

 I looked into the availability of suitable limiters. Mini Circuits
 don’t seem to have any with output power below 0 dBm. I found the
 following two models from Herotek and RF-LAMBDA which limit at -10
 dBm, but they are quite costly (~£600 excl. VAT) and the lead time
 is 6 to 10 weeks. Does anyone know of a better solution?

  

 http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf

 http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf

  

 Thanks & regards,

 Jan

You could install a notch filter for the other VHF frequency that is
most likely to cause you issues.

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House by the Symantec.Cloud Anti-virus Service.

This communication, together with any files or attachments transmitted
with it contains information which is confidential and may be subject
to legal privilege and is intended solely for the use by the person(s)
or entity to whom it is addressed. If you are not the intended
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reliance on it. If you have received this communication in error,
please notify postmaster@thls.org mailto:postmaster@thls.org and
delete it from your computer systems.

Trinity House reserves the right to monitor all communications for
lawful purposes. Receipt of this email does not imply consent to use
or provide this email address, or any others contained therein, to any
third party for any purposes. The contents of this email are protected
under international copyright law.

To save energy and paper please print this email only if you really
need to.

This email originated from: "The Corporation of Trinity House of
Deptford Strond" which is incorporated by Royal Charter in England and
Wales. The Royal Charter number is RC 000622. The Registered office is
Trinity House, Tower Hill, London, EC3N 4DH. Website:
http://www.trinityhouse.co.uk

USRP-users mailing list
USRP-users@lists.ettus.com mailto:USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

USRP-users mailing list
USRP-users@lists.ettus.com
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

Dear Jan, Well, in that case, a bandpass that only lets through your signal of interest surely sounds the most "high quality" solution, but it would limit your flexibility, as you would have to change that filter depending on what frequency you want to receive. Protection diodes for high bandwidths / Gigahertz frequencies and low powers are inherently hard to get -- low powers imply thin semiconductor interfaces, thin semiconductor interfaces imply small separation between positive and negative charges, which implies high capacitance, which implies low-pass characteristics if inserted between signal line and ground. This quickly boils down to a matter of money: Of course you could "just" use attenuators and a properly cooled LNA close to the antenna... Best regards, Marcus On 03/03/2016 10:37 AM, Jan Safar via USRP-users wrote: > > Hi Marcus, > > > > Thank you for your reply. Unfortunately a notch filter does not seem > to be a practical proposition for our application. There are normally > more than one frequency that could cause problems and different > frequencies may be in use at different locations (our terminals are > mobile). > > > > Jan > > > > *From:*USRP-users [mailto:usrp-users-bounces@lists.ettus.com] *On > Behalf Of *Marcus D. Leech via USRP-users > *Sent:* 02 March 2016 16:12 > *To:* usrp-users@lists.ettus.com > *Subject:* Re: [USRP-users] USRP Input Protection > > > > On 03/02/2016 05:19 AM, Jan Safar via USRP-users wrote: > > Hello, > > > > We are looking to use the E310 for some over-the-air tests in the > VHF band. In our application we need to install our antennas > within a few meters (say 3 to 5 m) of another VHF system antenna. > The transmitter power of the co-located unit can be up to 25 W, > antennas for both systems are typically 0 dBd omnidirectional. The > interfering transmissions are intermittent and can be as close as > on the adjacent channel. The stated maximum input power for all > USRPs is -15 dBm; for the E310 and at VHF, the limit is probably > somewhat higher but Ettus haven’t been able to provide an exact > figure. > > > > I’m wondering if anyone can advise on how to protect the USRP > input in this scenario? > > > > I looked into the availability of suitable limiters. Mini Circuits > don’t seem to have any with output power below 0 dBm. I found the > following two models from Herotek and RF-LAMBDA which limit at -10 > dBm, but they are quite costly (~£600 excl. VAT) and the lead time > is 6 to 10 weeks. Does anyone know of a better solution? > > > > http://www.herotek.com/datasheets/pdf/Pin_Diode_Very_Low_Leakage_Limiters_10MHz-18GHz_LL_Series.pdf > > http://www.rflambda.com/pdf/limiter/RFAPLT01M05M.pdf > > > > Thanks & regards, > > Jan > > You could install a notch filter for the other VHF frequency that is > most likely to cause you issues. > > > > ********************************************************************** > This e-mail has been scanned for all viruses on behalf of Trinity > House by the Symantec.Cloud Anti-virus Service. > > This communication, together with any files or attachments transmitted > with it contains information which is confidential and may be subject > to legal privilege and is intended solely for the use by the person(s) > or entity to whom it is addressed. If you are not the intended > recipient you must not copy, distribute, publish or take any action in > reliance on it. If you have received this communication in error, > please notify postmaster@thls.org <mailto:postmaster@thls.org> and > delete it from your computer systems. > > Trinity House reserves the right to monitor all communications for > lawful purposes. Receipt of this email does not imply consent to use > or provide this email address, or any others contained therein, to any > third party for any purposes. The contents of this email are protected > under international copyright law. > > *To save energy and paper please print this email only if you really > need to.* > > This email originated from: "The Corporation of Trinity House of > Deptford Strond" which is incorporated by Royal Charter in England and > Wales. The Royal Charter number is RC 000622. The Registered office is > Trinity House, Tower Hill, London, EC3N 4DH. Website: > http://www.trinityhouse.co.uk > > ********************************************************************* > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com <mailto:USRP-users@lists.ettus.com> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

MD

Marcus D. Leech

Thu, Mar 3, 2016 2:55 PM

On 03/03/2016 07:40 AM, Marcus Müller via USRP-users wrote:

Dear Jan,

Well, in that case, a bandpass that only lets through your signal of
interest surely sounds the most "high quality" solution, but it would
limit your flexibility, as you would have to change that filter
depending on what frequency you want to receive.

Protection diodes for high bandwidths / Gigahertz frequencies and low
powers are inherently hard to get -- low powers imply thin
semiconductor interfaces, thin semiconductor interfaces imply small
separation between positive and negative charges, which implies high
capacitance, which implies low-pass characteristics if inserted
between signal line and ground.

This quickly boils down to a matter of money: Of course you could
"just" use attenuators and a properly cooled LNA close to the antenna...

Best regards,
Marcus

There are two issues at play here--one of which is about protecting the
USRP input, the other is about preserving dynamic range/signal-quality
in the presence of very loud adjacent signals.

Even if one found an RF limiter diode that would start clamping at very
low input powers, while that would protect the downstream device,
there'd still be horrible signal quality issues during the time said
diode is clamping.

This is why at, for example, repeater sites where there may be dozens of
different TX and RX for different purposes, they use fairly
aggressive analog filtering. Without that, the physics of the
situation simply won't allow linear operation of your RX chain, even
ignoring
potential damage.

On 03/03/2016 07:40 AM, Marcus Müller via USRP-users wrote: > Dear Jan, > > Well, in that case, a bandpass that only lets through your signal of > interest surely sounds the most "high quality" solution, but it would > limit your flexibility, as you would have to change that filter > depending on what frequency you want to receive. > > Protection diodes for high bandwidths / Gigahertz frequencies and low > powers are inherently hard to get -- low powers imply thin > semiconductor interfaces, thin semiconductor interfaces imply small > separation between positive and negative charges, which implies high > capacitance, which implies low-pass characteristics if inserted > between signal line and ground. > > This quickly boils down to a matter of money: Of course you could > "just" use attenuators and a properly cooled LNA close to the antenna... > > Best regards, > Marcus There are two issues at play here--one of which is about protecting the USRP input, the other is about preserving dynamic range/signal-quality in the presence of very loud adjacent signals. Even if one found an RF limiter diode that would start clamping at very low input powers, while that would protect the downstream device, there'd still be horrible signal quality issues during the time said diode is clamping. This is why at, for example, repeater sites where there may be dozens of different TX and RX for different purposes, they use fairly aggressive analog filtering. Without that, the physics of the situation simply won't allow linear operation of your RX chain, even ignoring potential damage.