Crosstalk? With the same signal? On Tue, Oct 9, 2012 at 4:31 AM, Edgardo Molina <[email protected]> wrote:
> Dear Group, > > Good evening. I just arrived home after the first day of conferences at > the Electrical Metrology Forum 2012 at Mexico's metrology center CENAM. I > attended several presentations of time and frequency, very interesting > indeed. At last I understood some concepts hard to land in theory. I will > be attending the whole week long and half of next week. I will have the > pleasure and honour to meet Dr. Judah Levine from NIST, who has shown a > very nice attitude towards me and accepted to talk a little bit around my > thesis in network synchronization. > > Now to the point if you kindly allow. I got involved in a round table > discussion around the use of GPS antennas for time and frequency GPS > receivers. I tried to make some points from my personal perspective. I got > resistance from the audience and the topic went hot very quickly and didn't > set at the end. Honestly I would like to share my doubts and opinions with > you in order to enhance my experience about the topic. In the end it could > also be beneficial to close this debate tomorrow while attending to CENAM's > time and frequency forum. > > Facts and thoughts: > > 1. The time and frequency attendees at CENAM`s time and frequency forum > is reluctant to use GPS antenna splitters for a number of reasons I > couldn't conceive. > 1.1 They argued that cross talk could happen among ports. I doubt > it with the newer models. I have experience with HP and Symmetricom units > and they state their products cancel cross talk. > 1.2 They argued that there could be problems from the power > feeding of the antenna and mismatches at the receiver antenna port > voltages. Again I doubt it if one uses receivers in the same voltage range > > 2. I have been experimenting with GPS constellation coverage with > different brands of antennas. I have found different gains, different > radiation patterns and as a result different satellites in view for > identical GPS receivers. > 2.1 I have found that using a single antenna and a two port HP > splitter I get the same radiation pattern, gain and identical satellites in > view for a set of identical receivers. For comparison purposes I feel this > is an adequate scenario. > It is easier for me to take care of the transmission line length > and errors caused by phase differences, attenuation and delays. > 2.2 Two identical GPS receivers each one with it's own antenna, > could eventually cause spatial diversity reception for a system of two > receivers conceptually set as one for comparison purposes. Different > satellites being tracked on > each receiver if not connected to a common antenna. Even if > antennas and transmission lines are identical. > > Question is: Am I wrong doing the above mentioned assumptions while > considering the use of GPS transmission line splitters? I which scenarios > are the splitters recommended? In which cases they are rather not to be > considered? > > Better ask as to start buying more antennas or feel comfortable with my > original RF distribution design using splitters. > > Your kind comments and expert advise is always welcome. Thank you! > > > Best regards, > > > > Edgardo Molina > Dirección IPTEL > > www.iptel.net.mx > > T : 55 55 55202444 > M : 04455 20501854 > > Piensa en Bits SA de CV > > > > Información anexa: > > > > > CONFIDENCIALIDAD DE INFORMACION > > Este mensaje tiene carácter confidencial. Si usted no es el destinarario > de este mensaje, le suplicamos se lo notifique al remitente mediante un > correo electrónico y que borre el presente mensaje y sus anexos de su > computadora sin retener una copia de los mismos. Queda estrictamente > prohibido copiar este mensaje o hacer usode el para cualquier propósito o > divulgar su en forma parcial o total su contenido. Gracias. > > > NON-DISCLOSURE OF INFORMATION > > This email is strictly confidential and may also be privileged. If you are > not the intended recipient please immediately advise the sender by replying > to this e-mail and then deleting the message and its attachments from your > computer without keeping a copy. It is strictly forbidden to copy it or use > it for any purpose or disclose its contents to any third party. Thank you. > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
