R

Raj

Tue, Jan 25, 2011 3:25 PM

TimeNut folks,

    A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious!

    Any ideas and/or thoughts?

Cheers

--
Raj, VU2ZAP
Bangalore, India.

TimeNut folks, A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious! Any ideas and/or thoughts? Cheers -- Raj, VU2ZAP Bangalore, India.

MJ

Mark J. Blair

Tue, Jan 25, 2011 3:44 PM

On Jan 25, 2011, at 7:25 AM, Raj wrote:

    A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious!

    Any ideas and/or thoughts?

There's a software tool called Kalibrate for use with the GNU Radio software and USRP radio hardware, which uses GSM base station signals as a standard to measure the frequency offset of the USRP's oscillator. It's not really a time-nutty application, but it serves as an example of using cellular base stations as a frequency reference.

http://thre.at/kalibrate/

GNU Radio is a free open-source development environment for implementing software-defined radios. The USRP is one of the more popular RF hardware options for use with GNU Radio.

http://gnuradio.org/redmine/wiki/gnuradio

--
Mark J. Blair, NF6X nf6x@nf6x.net
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.

On Jan 25, 2011, at 7:25 AM, Raj wrote: > A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious! > > Any ideas and/or thoughts? There's a software tool called Kalibrate for use with the GNU Radio software and USRP radio hardware, which uses GSM base station signals as a standard to measure the frequency offset of the USRP's oscillator. It's not really a time-nutty application, but it serves as an example of using cellular base stations as a frequency reference. http://thre.at/kalibrate/ GNU Radio is a free open-source development environment for implementing software-defined radios. The USRP is one of the more popular RF hardware options for use with GNU Radio. http://gnuradio.org/redmine/wiki/gnuradio -- Mark J. Blair, NF6X <nf6x@nf6x.net> Web page: http://www.nf6x.net/ GnuPG public key available from my web page.

CA

Chris Albertson

Tue, Jan 25, 2011 3:53 PM

There are commercial radio clocks that receive the CDMA signal and use
it for timing. Here is one company and they have a write-up comparing
CDMA to GPS. Short answer, GPS works at the nanosecond level CDMA at
the microsecond level but CDMA can go through walls while GPS needs to
see the sky
http://www.endruntechnologies.com/gps-cdma.htm

On Tue, Jan 25, 2011 at 7:25 AM, Raj vu2zap@gmail.com wrote:

TimeNut folks,

A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious!

Any ideas and/or thoughts?

Cheers

--
Raj, VU2ZAP
Bangalore, India.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

--

Chris Albertson
Redondo Beach, California

There are commercial radio clocks that receive the CDMA signal and use it for timing. Here is one company and they have a write-up comparing CDMA to GPS. Short answer, GPS works at the nanosecond level CDMA at the microsecond level but CDMA can go through walls while GPS needs to see the sky http://www.endruntechnologies.com/gps-cdma.htm On Tue, Jan 25, 2011 at 7:25 AM, Raj <vu2zap@gmail.com> wrote: > TimeNut folks, > > A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious! > > Any ideas and/or thoughts? > > Cheers > > -- > Raj, VU2ZAP > Bangalore, India. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- ===== Chris Albertson Redondo Beach, California

BC

Bob Camp

Tue, Jan 25, 2011 5:12 PM

Hi

Several of the "big guys" have tried this approach.

The problem seems to be that you are at the mercy of the guy who is
transmitting the signal. He may (or may not) be very good at keeping things
running right. Regulations may (or may not) actually require him to lock his
signal to GPS.

A lot of these systems work just fine at > 1.0 x 10^-8 off frequency. You
have to keep the slots lined up between them, but as long as everybody
agrees on alignment, they keep running fine. There's a lot that you can get
away with and still be providing a dial tone.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Raj
Sent: Tuesday, January 25, 2011 10:25 AM
To: Time Nuts
Subject: [time-nuts] Frequency based on mobile services

TimeNut folks,

    A thought occurred to me that there should be a way to lock our

OCXO/TCXOs to cell phone services signals that that is present almost
everywhere. I am not conversant with cellular technology so I am curious!

    Any ideas and/or thoughts?

Cheers

--
Raj, VU2ZAP
Bangalore, India.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi Several of the "big guys" have tried this approach. The problem seems to be that you are at the mercy of the guy who is transmitting the signal. He may (or may not) be very good at keeping things running right. Regulations may (or may not) actually require him to lock his signal to GPS. A lot of these systems work just fine at > 1.0 x 10^-8 off frequency. You have to keep the slots lined up between them, but as long as everybody agrees on alignment, they keep running fine. There's a lot that you can get away with and still be providing a dial tone. Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Raj Sent: Tuesday, January 25, 2011 10:25 AM To: Time Nuts Subject: [time-nuts] Frequency based on mobile services TimeNut folks, A thought occurred to me that there should be a way to lock our OCXO/TCXOs to cell phone services signals that that is present almost everywhere. I am not conversant with cellular technology so I am curious! Any ideas and/or thoughts? Cheers -- Raj, VU2ZAP Bangalore, India. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

MD

Magnus Danielson

Tue, Jan 25, 2011 7:39 PM

On 25/01/11 18:12, Bob Camp wrote:

Hi

Several of the "big guys" have tried this approach.

The problem seems to be that you are at the mercy of the guy who is
transmitting the signal. He may (or may not) be very good at keeping things
running right. Regulations may (or may not) actually require him to lock his
signal to GPS.

A lot of these systems work just fine at> 1.0 x 10^-8 off frequency. You
have to keep the slots lined up between them, but as long as everybody
agrees on alignment, they keep running fine. There's a lot that you can get
away with and still be providing a dial tone.

GSM and hence UMTS has 50 ppb requirements in the base station
frequency. For GSM no timing is required, but synchronisation of several
base-stations has been shown to improve hand-over performance.
Depending on the operator you tune in to, it may or may not be locked to
GPS or similar... but may also run from caesium beams somewhere
completely different, if so you are only guaranteed 1E-11 in frequency
long-term.

There is many systems, and you also need to tune in to the right signal.
GSM for instance may frequency jump regularly.

Digital TV signals may be also be used. Depending on which mode the
network operate in the transmitters may be undisciplined or locked to
GPS directly or indirectly. DVB-T for instance has regular pilot-tones
in the spectrum. A DVB-T receiver is a nice exercise... :)

It's possible, but not trivial.

Cheers,
Magnus

On 25/01/11 18:12, Bob Camp wrote: > Hi > > Several of the "big guys" have tried this approach. > > The problem seems to be that you are at the mercy of the guy who is > transmitting the signal. He may (or may not) be very good at keeping things > running right. Regulations may (or may not) actually require him to lock his > signal to GPS. > > A lot of these systems work just fine at> 1.0 x 10^-8 off frequency. You > have to keep the slots lined up between them, but as long as everybody > agrees on alignment, they keep running fine. There's a lot that you can get > away with and still be providing a dial tone. GSM and hence UMTS has 50 ppb requirements in the base station frequency. For GSM no timing is required, but synchronisation of several base-stations has been shown to improve hand-over performance. Depending on the operator you tune in to, it may or may not be locked to GPS or similar... but may also run from caesium beams somewhere completely different, if so you are only guaranteed 1E-11 in frequency long-term. There is many systems, and you also need to tune in to the right signal. GSM for instance may frequency jump regularly. Digital TV signals may be also be used. Depending on which mode the network operate in the transmitters may be undisciplined or locked to GPS directly or indirectly. DVB-T for instance has regular pilot-tones in the spectrum. A DVB-T receiver is a nice exercise... :) It's possible, but not trivial. Cheers, Magnus

R

Raj

Wed, Jan 26, 2011 8:23 AM

Thanks for all the links, info and comments guys!

Hi

Several of the "big guys" have tried this approach.

The problem seems to be that you are at the mercy of the guy who is
transmitting the signal. He may (or may not) be very good at keeping things
running right. Regulations may (or may not) actually require him to lock his
signal to GPS.

A lot of these systems work just fine at> 1.0 x 10^-8 off frequency. You
have to keep the slots lined up between them, but as long as everybody
agrees on alignment, they keep running fine. There's a lot that you can get
away with and still be providing a dial tone.

GSM and hence UMTS has 50 ppb requirements in the base station frequency. For GSM no timing is required, but synchronisation of several base-stations has been shown to improve hand-over performance.
Depending on the operator you tune in to, it may or may not be locked to GPS or similar... but may also run from caesium beams somewhere completely different, if so you are only guaranteed 1E-11 in frequency long-term.

There is many systems, and you also need to tune in to the right signal. GSM for instance may frequency jump regularly.

Digital TV signals may be also be used. Depending on which mode the network operate in the transmitters may be undisciplined or locked to GPS directly or indirectly. DVB-T for instance has regular pilot-tones in the spectrum. A DVB-T receiver is a nice exercise... :)

It's possible, but not trivial.

Cheers,
Magnus

--
Raj, VU2ZAP
Bangalore, India.

Thanks for all the links, info and comments guys! >>Hi >> >>Several of the "big guys" have tried this approach. >> >>The problem seems to be that you are at the mercy of the guy who is >>transmitting the signal. He may (or may not) be very good at keeping things >>running right. Regulations may (or may not) actually require him to lock his >>signal to GPS. >> >>A lot of these systems work just fine at> 1.0 x 10^-8 off frequency. You >>have to keep the slots lined up between them, but as long as everybody >>agrees on alignment, they keep running fine. There's a lot that you can get >>away with and still be providing a dial tone. > >GSM and hence UMTS has 50 ppb requirements in the base station frequency. For GSM no timing is required, but synchronisation of several base-stations has been shown to improve hand-over performance. >Depending on the operator you tune in to, it may or may not be locked to GPS or similar... but may also run from caesium beams somewhere completely different, if so you are only guaranteed 1E-11 in frequency long-term. > >There is many systems, and you also need to tune in to the right signal. GSM for instance may frequency jump regularly. > >Digital TV signals may be also be used. Depending on which mode the network operate in the transmitters may be undisciplined or locked to GPS directly or indirectly. DVB-T for instance has regular pilot-tones in the spectrum. A DVB-T receiver is a nice exercise... :) > >It's possible, but not trivial. > >Cheers, >Magnus > -- Raj, VU2ZAP Bangalore, India.

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Frequency based on mobile services

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