Re: [time-nuts] latest on the lightsquared 'saga'
Robert wrote: Hey, at least you got vouchers. Here in Cambridge UK the analogue signal goes off next weekend and you are on your own for converters. If you had ever seen the video that comes out of the converters made to the voucher price point, you might not be so keen on the program. Then again, many Brits seem to tolerate the horrid video that Sky TV sends out;-) Best regards, Charles ___ 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.
Re: [time-nuts] latest on the lightsquared 'saga'
On 4 March 2011 23:26, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: Robert wrote: Hey, at least you got vouchers. Here in Cambridge UK the analogue signal goes off next weekend and you are on your own for converters. If you had ever seen the video that comes out of the converters made to the voucher price point, you might not be so keen on the program. Then again, many Brits seem to tolerate the horrid video that Sky TV sends out ;-) But at least it's in PAL not Never Twice The Same Colour :) Steve Best regards, Charles ___ 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. -- Steve Rooke - ZL3TUV G8KVD The only reason for time is so that everything doesn't happen at once. - Einstein ___ 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.
Re: [time-nuts] latest on the lightsquared 'saga'
Hi Indeed this is my fear. The authorization really has very little to do with filling in dark holes in the sat coverage and everything to do with setting up a full blown terrestrial system. This is not going to be a far away and easily ignored thing. If you have cell phone coverage, you will likely have this stuff as well. The level may or may not be enough to take your timing gear off the air. It will take it down for a number of us. Bob On Mar 3, 2011, at 5:38 PM, Charles P. Steinmetz wrote: Robert wrote: What gets me (I'm an outsider in the UK), is that they seem to have used the excuse of Urban Canyon lack of space based broadband to hi-jack the frequencies for ground use. What's the betting 99% of the traffic is ground based, not space? Even though the Urban Canyonites could of course use fibre-optic broadband. The FCC believes (and studies show) that mobile broadband is the Next Big Thing (some studies predict that the US will need 35x more mobile broadband spectrum before long). So, most of the FCC's focus is on serving mobile users, who cannot be served by fiber optics. To that end, the FCC is trying to add 500 MHz of spectrum that is useful for mobile broadband over the next 10 years, 300 MHz of it within 5 years: (http://www.broadband.gov/plan/). Now, 500 MHz is nowhere near 35x what is now available, so even if the FCC is fully successful it presumably will not meet the demand -- but nobody at the FCC or in Congress seems to have noticed this. Further, there is a limited amount of spectrum that is truly useful for mobile broadband -- high enough that antennas for handheld devices are manageable, but low enough to penetrate into buildings and other dark zones -- so 500 MHz will be very, very hard to find. The plan appears to include repacking all over-the-air television stations into the VHF TV spectrum, to free up the UHF TV spectrum (ironically, immediately after converting the industry to a DTV modulation scheme that has severe multipath problems at VHF, so stations voluntarily packed themselves into the UHF spectrum during the transition). MSS spectrum in the L-band (and elsewhere) has historically not been heavily utilized because of the cost of infrastructure and the less-than-stellar performance. The first step toward making this spectrum more useful was to allow MSS licensees to construct an ancillary terrestrial component -- cellular base stations on towers -- to fill in holes. The second step (Lightsquared and other MSS licensees who will follow) is to waive some of the provisions that make the terrestrial component ancillary (i.e., to allow much more widespread terrestrial use). The third step is to authorize purely terrestrial services to operate in the MSS bands (the FCC has already officially proposed adding such allotments, and everyone in the communications industry expects it to adopt the proposal): http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-126A1_Rcd.pdf Bob asked where the 40k terrestrial base stations will go. That number is on par with Verizon, T-Mobile, and ATT, so one might expect the coverage to be similar (Sprint has about 46k sites for its 1.9 GHz network). Best regards, Charles ___ 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. ___ 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.
Re: [time-nuts] latest on the lightsquared 'saga'
Bob wrote: Indeed this is my fear. The authorization really has very little to do with filling in dark holes in the sat coverage and everything to do with setting up a full blown terrestrial system. Correct. LightSquared's business model is to be a wholesale network provider. The FCC waiver explicitly allows LS to provide terrestrial network capacity only, to customers who do not care about satellite connectivity (which could be most of them). This is a preview of the future, in which there will be other terrestrial licensees on the spectrum that won't even need to have satellites in orbit. However, if these terrestrial networks do interfere with GPS in any significant way, the GPS interests will howl and something likely will be done. For that matter, LS will be relying on GPS timing receivers mounted next to its base stations to make its LTE network function. So don't give up just yet. Best regards, Charles ___ 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.
[time-nuts] Replacement for TADD-1?
Does anyone know if there is a planned or upcoming replacement for the Tapr TADD-1? Thanks, Dan ac6ao ___ 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.
Re: [time-nuts] Replacement for TADD-1?
Look for a message from John Miles dated Feb 23 with this subject line: Re: [time-nuts] was there ever a conclusion on distribution amps ? --Original Message-- From: Dan Rae Sender: time-nuts-boun...@febo.com To: Time-Nuts ReplyTo: dan...@verizon.net ReplyTo: Time-Nuts Subject: [time-nuts] Replacement for TADD-1? Sent: Mar 4, 2011 11:22 AM Does anyone know if there is a planned or upcoming replacement for the Tapr TADD-1? Thanks, Dan ac6ao ___ 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. Sent from my Verizon Wireless BlackBerry ___ 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.
Re: [time-nuts] Replacement for TADD-1?
On 3/4/2011 12:22 PM, Dan Rae wrote: Does anyone know if there is a planned or upcoming replacement for the Tapr TADD-1? We're working on a very high performance distribution amplifier that will replace the TADD-1 and also be available in a single-channel version for isolation/buffer amp purposes. It's a little too early to speculate on availability dates (or price), but we're just finishing board layout for the single-channel version and about to order the prototype boards. John ___ 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.
[time-nuts] GPS Filter
Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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.
[time-nuts] Tracor 304D Rubidium Standard
As my age is catching up to me and as part of the process of making life a bit simpler, I've decided to dispose of a number of the precision time items that I've acquired over the years. I've put a few things on ebay that might be of interest, but the 304D is really quite nice and is fitted with a Patek mechanical clock. If it's not ok to mention these things on the list just let me know and I won't do it again... Bill S www.precisionclocks.com ___ 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.
Re: [time-nuts] Tracor 304D Rubidium Standard
Hi Bill, Good to hear from you. Thanks for posting and, yes, it's ok to mention your items. Tracor 304D http://cgi.ebay.com/260744992504 Austron 1210D http://cgi.ebay.com/260744999533 etc. I should make everyone on the list aware that I first caught a serious case of the time bug in the early 1990's, partly because of Tom Clark's work with the Oncore VP timing receiver, partly because of Corby's handwritten flyers about cesium standards for sale, and partly because of Bill's already large collection of vintage time frequency gear (which I found out about through a small ad in Nuts Volts). It's safe to say that the time-nuts list would not be here except for my seeing his ads in Nuts Volts more than 15 years ago and realizing that I was not alone with this collecting passion. Thanks, /tvb http://www.leapsecond.com/time-nuts.htm - Original Message - From: Bill S w...@jbpet.com To: time-nuts@febo.com Sent: Friday, March 04, 2011 10:38 AM Subject: [time-nuts] Tracor 304D Rubidium Standard As my age is catching up to me and as part of the process of making life a bit simpler, I've decided to dispose of a number of the precision time items that I've acquired over the years. I've put a few things on ebay that might be of interest, but the 304D is really quite nice and is fitted with a Patek mechanical clock. If it's not ok to mention these things on the list just let me know and I won't do it again... Bill S www.precisionclocks.com ___ 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.
Re: [time-nuts] GPS Filter
On Fri, Mar 4, 2011 at 10:31 AM, Bob Camp li...@rtty.us wrote: now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Most GPS antenna are active. I'm a bit more worried about the preamps built into the antenna. A filter external to the antenna will not protect the built-in preamp. But there are all kinds of designs for home built GPS antenna. A helix antenna is not hard to make. Timing GPSes at fixed sites can use antenna that have a deep null aimed at the nearby transmitter (which is also fixed) People at fixed sites will have it easy. Mobile GPS users will not be able use antenna design. -- = Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] GPS Filter
Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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.
Re: [time-nuts] Tracor 304D Rubidium Standard
Nice RB ref But really like your clock site Wow. On Fri, Mar 4, 2011 at 1:38 PM, Bill S w...@jbpet.com wrote: As my age is catching up to me and as part of the process of making life a bit simpler, I've decided to dispose of a number of the precision time items that I've acquired over the years. I've put a few things on ebay that might be of interest, but the 304D is really quite nice and is fitted with a Patek mechanical clock. If it's not ok to mention these things on the list just let me know and I won't do it again... Bill S www.precisionclocks.com ___ 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. ___ 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.
Re: [time-nuts] GPS Filter
The discussion got me to thinking about how we used to filter out nearby interference on amateur TV - namely by using interdigital filters. This led to a search for GPS interdigital filters which i did indeed find. See Alison Microwave website at http://www.amlant.co.uk/DetailsAD430.htm for one example of an integrated antenna/filter/preamp. (I'm sure these aren't cheap, but I haven't asked.) As for retrofitting, you could add a filter after the antenna/amplifier assembly but I might be concerned that the amplified GPS antenna is pretty wide and may have trouble with a Lightsquared transmitter nearby. There are passive antennas though, and there are in-line amps - you'd need to add the filter in between. We made these ourselves for 439 and 1296 MHz - GPS L1 isn't much above that so with some care it should be doable. The tuning can be finicky though :\ Ziggy On 03/04/2011 03:31 PM, John Ackermann N8UR wrote: Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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. ___ 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.
Re: [time-nuts] GPS Filter
I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ziggy Sent: Friday, March 04, 2011 7:47 PM To: time-nuts@febo.com Subject: Re: [time-nuts] GPS Filter The discussion got me to thinking about how we used to filter out nearby interference on amateur TV - namely by using interdigital filters. This led to a search for GPS interdigital filters which i did indeed find. See Alison Microwave website at http://www.amlant.co.uk/DetailsAD430.htm for one example of an integrated antenna/filter/preamp. (I'm sure these aren't cheap, but I haven't asked.) As for retrofitting, you could add a filter after the antenna/amplifier assembly but I might be concerned that the amplified GPS antenna is pretty wide and may have trouble with a Lightsquared transmitter nearby. There are passive antennas though, and there are in-line amps - you'd need to add the filter in between. We made these ourselves for 439 and 1296 MHz - GPS L1 isn't much above that so with some care it should be doable. The tuning can be finicky though :\ Ziggy On 03/04/2011 03:31 PM, John Ackermann N8UR wrote: Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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. ___ 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. ___ 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.
Re: [time-nuts] GPS Filter
I'm not so sure. A filter ahead of a preamp significantly increases the system Noise Temperature. GPS signals are weak and link margins are small. The receiver preamps are already very low noise. I'd think that a narrow filter might well drive up the systen NF to the point it'd be useless. FWIW, -John = I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ziggy Sent: Friday, March 04, 2011 7:47 PM To: time-nuts@febo.com Subject: Re: [time-nuts] GPS Filter The discussion got me to thinking about how we used to filter out nearby interference on amateur TV - namely by using interdigital filters. This led to a search for GPS interdigital filters which i did indeed find. See Alison Microwave website at http://www.amlant.co.uk/DetailsAD430.htm for one example of an integrated antenna/filter/preamp. (I'm sure these aren't cheap, but I haven't asked.) As for retrofitting, you could add a filter after the antenna/amplifier assembly but I might be concerned that the amplified GPS antenna is pretty wide and may have trouble with a Lightsquared transmitter nearby. There are passive antennas though, and there are in-line amps - you'd need to add the filter in between. We made these ourselves for 439 and 1296 MHz - GPS L1 isn't much above that so with some care it should be doable. The tuning can be finicky though :\ Ziggy On 03/04/2011 03:31 PM, John Ackermann N8UR wrote: Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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. ___ 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. ___ 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. ___ 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.
Re: [time-nuts] GPS Filter
Well, as you said John, for FWIW. In this case not much. As said low loss, so increase in noise temp would be minimal, and, if it makes a difference between an overloaded front end or a 0.5 dB loss in NF, it will be welcome. Heck, we use filters in front of most of our Satcom LNBs at 21 GHz with minimal effect. Been there and done that, as the saying goes. If necessary the small increase in noise temp can easily be overcome by a slightly larger aperture, especially since a view of the full sky is not really necessary and birds below certain elevation angles are typically ignored by software settings of one's own choosing. And again, I was talking about people who have done this and can do it again. It would not be an issue for me. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Friday, March 04, 2011 8:47 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Filter I'm not so sure. A filter ahead of a preamp significantly increases the system Noise Temperature. GPS signals are weak and link margins are small. The receiver preamps are already very low noise. I'd think that a narrow filter might well drive up the systen NF to the point it'd be useless. FWIW, -John = I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ziggy Sent: Friday, March 04, 2011 7:47 PM To: time-nuts@febo.com Subject: Re: [time-nuts] GPS Filter The discussion got me to thinking about how we used to filter out nearby interference on amateur TV - namely by using interdigital filters. This led to a search for GPS interdigital filters which i did indeed find. See Alison Microwave website at http://www.amlant.co.uk/DetailsAD430.htm for one example of an integrated antenna/filter/preamp. (I'm sure these aren't cheap, but I haven't asked.) As for retrofitting, you could add a filter after the antenna/amplifier assembly but I might be concerned that the amplified GPS antenna is pretty wide and may have trouble with a Lightsquared transmitter nearby. There are passive antennas though, and there are in-line amps - you'd need to add the filter in between. We made these ourselves for 439 and 1296 MHz - GPS L1 isn't much above that so with some care it should be doable. The tuning can be finicky though :\ Ziggy On 03/04/2011 03:31 PM, John Ackermann N8UR wrote: Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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. ___ 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.
Re: [time-nuts] GPS Filter
Preamps with NFs under 0.5 dB are available for the 1.5 GHz region. IMO a doubling of system noise temperature is non-trivial. -John === Well, as you said John, for FWIW. In this case not much. As said low loss, so increase in noise temp would be minimal, and, if it makes a difference between an overloaded front end or a 0.5 dB loss in NF, it will be welcome. Heck, we use filters in front of most of our Satcom LNBs at 21 GHz with minimal effect. Been there and done that, as the saying goes. If necessary the small increase in noise temp can easily be overcome by a slightly larger aperture, especially since a view of the full sky is not really necessary and birds below certain elevation angles are typically ignored by software settings of one's own choosing. And again, I was talking about people who have done this and can do it again. It would not be an issue for me. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Friday, March 04, 2011 8:47 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Filter I'm not so sure. A filter ahead of a preamp significantly increases the system Noise Temperature. GPS signals are weak and link margins are small. The receiver preamps are already very low noise. I'd think that a narrow filter might well drive up the systen NF to the point it'd be useless. FWIW, -John = I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ziggy Sent: Friday, March 04, 2011 7:47 PM To: time-nuts@febo.com Subject: Re: [time-nuts] GPS Filter The discussion got me to thinking about how we used to filter out nearby interference on amateur TV - namely by using interdigital filters. This led to a search for GPS interdigital filters which i did indeed find. See Alison Microwave website at http://www.amlant.co.uk/DetailsAD430.htm for one example of an integrated antenna/filter/preamp. (I'm sure these aren't cheap, but I haven't asked.) As for retrofitting, you could add a filter after the antenna/amplifier assembly but I might be concerned that the amplified GPS antenna is pretty wide and may have trouble with a Lightsquared transmitter nearby. There are passive antennas though, and there are in-line amps - you'd need to add the filter in between. We made these ourselves for 439 and 1296 MHz - GPS L1 isn't much above that so with some care it should be doable. The tuning can be finicky though :\ Ziggy On 03/04/2011 03:31 PM, John Ackermann N8UR wrote: Here's a measurement we did a few years ago on the HP 58535A: http://www.febo.com/pages/hp_gps_splitter/port_1_hp_58535a_two_port_amp.png John On 3/4/2011 1:31 PM, Bob Camp wrote: Hi Ok, now it's pretty obvious the RF world near your GPS will be changing a *lot* in the near future. Lightsquared and a bunch of similar outfits will be camping out right next door with very high power gear. They will be running 1.5KW from somewhere in town. GPS is running 30 watts from off planet. Has anybody tossed the various HP / Symmetricom GPS splitters on a network analyzer? If so, what do the filters in them look like? I probably should corner the market on these things before asking a question like that. The new neighbors will be at 1525 to 1559 MHz. GPS L1 is at 1575.42 MHz. That's what we are using for timing. L2 is down at 1227.5, right now it's mainly military use. Obviously these guys are a bigger deal for civilians than the military. So the question is - do the built in splitter filters have any real rejection 15 to 50 MHz off of center? Probably worth checking. It would be a pleasant surprise if they turned out to be useful. Bob ___ 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. ___ 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. ___ time-nuts
[time-nuts] Selling things on time-nuts
But really like your clock site Wow. www.precisionclocks.com Neat. Thanks for the heads up. -- I know about Bryan Mumford's web site: http://www.bmumford.com/clocks/emindex.html How many others am I missing? -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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.
Re: [time-nuts] GPS Filter
I used the 0.5 dB number for loss as a worst case. Of course they are available. They are available even lower, and even at higher frequencies. Whether or not is trivial is not relevant. What is required is relevant. This would of course be relevant in small handheld disadvantaged GPS receivers, but, for roof mounted time-nuts use it should not be a problem. Even some indoor use it would be fine. If you really feel that you need less than 0.5 dB of NF, get the numbers. What is the typical RIP from the various birds at various locations? Then knowing Ga and NF you can calculate C/N and Eb/No required for the processors to work with acceptable error. Anyway, enough on this. This is something I can personally handle and am not worried. Besides, imagine if all of the sudden millions of Cell phones became useless. Just not going to happen. - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: J. Forster [mailto:j...@quik.com] Sent: Friday, March 04, 2011 9:09 PM To: Mike Feher Cc: 'Discussion of precise time and frequency measurement' Subject: RE: [time-nuts] GPS Filter Preamps with NFs under 0.5 dB are available for the 1.5 GHz region. IMO a doubling of system noise temperature is non-trivial. -John === Well, as you said John, for FWIW. In this case not much. As said low loss, so increase in noise temp would be minimal, and, if it makes a difference between an overloaded front end or a 0.5 dB loss in NF, it will be welcome. Heck, we use filters in front of most of our Satcom LNBs at 21 GHz with minimal effect. Been there and done that, as the saying goes. If necessary the small increase in noise temp can easily be overcome by a slightly larger aperture, especially since a view of the full sky is not really necessary and birds below certain elevation angles are typically ignored by software settings of one's own choosing. And again, I was talking about people who have done this and can do it again. It would not be an issue for me. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Friday, March 04, 2011 8:47 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Filter I'm not so sure. A filter ahead of a preamp significantly increases the system Noise Temperature. GPS signals are weak and link margins are small. The receiver preamps are already very low noise. I'd think that a narrow filter might well drive up the systen NF to the point it'd be useless. FWIW, -John = I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell ___ 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.
Re: [time-nuts] GPS Filter
There are far more portable GPS units than fixed, timing units. Furthermore, the consequences of a position error are far greater. Hence, a filter option may well not get rid of LightSquared issues for the majority of users users. -John === I used the 0.5 dB number for loss as a worst case. Of course they are available. They are available even lower, and even at higher frequencies. Whether or not is trivial is not relevant. What is required is relevant. This would of course be relevant in small handheld disadvantaged GPS receivers, but, for roof mounted time-nuts use it should not be a problem. Even some indoor use it would be fine. If you really feel that you need less than 0.5 dB of NF, get the numbers. What is the typical RIP from the various birds at various locations? Then knowing Ga and NF you can calculate C/N and Eb/No required for the processors to work with acceptable error. Anyway, enough on this. This is something I can personally handle and am not worried. Besides, imagine if all of the sudden millions of Cell phones became useless. Just not going to happen. - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: J. Forster [mailto:j...@quik.com] Sent: Friday, March 04, 2011 9:09 PM To: Mike Feher Cc: 'Discussion of precise time and frequency measurement' Subject: RE: [time-nuts] GPS Filter Preamps with NFs under 0.5 dB are available for the 1.5 GHz region. IMO a doubling of system noise temperature is non-trivial. -John === Well, as you said John, for FWIW. In this case not much. As said low loss, so increase in noise temp would be minimal, and, if it makes a difference between an overloaded front end or a 0.5 dB loss in NF, it will be welcome. Heck, we use filters in front of most of our Satcom LNBs at 21 GHz with minimal effect. Been there and done that, as the saying goes. If necessary the small increase in noise temp can easily be overcome by a slightly larger aperture, especially since a view of the full sky is not really necessary and birds below certain elevation angles are typically ignored by software settings of one's own choosing. And again, I was talking about people who have done this and can do it again. It would not be an issue for me. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Friday, March 04, 2011 8:47 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS Filter I'm not so sure. A filter ahead of a preamp significantly increases the system Noise Temperature. GPS signals are weak and link margins are small. The receiver preamps are already very low noise. I'd think that a narrow filter might well drive up the systen NF to the point it'd be useless. FWIW, -John = I used to make some interdigital filters and amplifiers in the early 80's for MDS TV reception in the 2.3 GHz range. One can easily fabricate a low loss narrow band filter at 1.5 GHz if need be, and as mentioned before, antennas should be easy as well. If this really becomes an issue, I am sure there will be a lot of solutions offered and anyone with some RF experience will also be able to handle it themselves. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell ___ 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.
[time-nuts] Selling things on time-nuts (or other lists)
Argh. Sorry for botching the Subject on my previous message. After a bit of typing I decided to split it into two, but that was after I had fixed the Subject and such. Sigh. So here is the other part... - My opinions on announcements vs advertising on lists... I hate blatant commercial advertising, more so the farther it is from the main topic of the list. I'm generally in favor of appropriate one-off advertisements/announcements by active members or even semi-active or lurkers if the gear is hard to find. If you are going to clutter up the list with a message, please include all the details of all the goodies you are selling. I prefer non-ebay, but if you have listed stuff on ebay, include their numbers and/or URLs. If you are an active (constructive) participant in a list/newsgroup/forum/whatever, I'm happy with a short signature tacked on the end of each message. 4 lines is the usual usenet limit. There is a gray area in responding to requests for where to get something. If it's widely available, I hate the responses that say nothing more than Me me me!!!. On the other hand, I really appreciate responses from vendors/reps who know what's going on and contribute useful details (technical or marketing). Synergy comes to mind as a good example. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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.
Re: [time-nuts] Selling things on time-nuts (or other lists)
Was looking at the site again. Bill Slocneks (Sorry for the spelling) Really amazing the quality of work. An incredible talent. On Fri, Mar 4, 2011 at 9:45 PM, Hal Murray hmur...@megapathdsl.net wrote: Argh. Sorry for botching the Subject on my previous message. After a bit of typing I decided to split it into two, but that was after I had fixed the Subject and such. Sigh. So here is the other part... - My opinions on announcements vs advertising on lists... I hate blatant commercial advertising, more so the farther it is from the main topic of the list. I'm generally in favor of appropriate one-off advertisements/announcements by active members or even semi-active or lurkers if the gear is hard to find. If you are going to clutter up the list with a message, please include all the details of all the goodies you are selling. I prefer non-ebay, but if you have listed stuff on ebay, include their numbers and/or URLs. If you are an active (constructive) participant in a list/newsgroup/forum/whatever, I'm happy with a short signature tacked on the end of each message. 4 lines is the usual usenet limit. There is a gray area in responding to requests for where to get something. If it's widely available, I hate the responses that say nothing more than Me me me!!!. On the other hand, I really appreciate responses from vendors/reps who know what's going on and contribute useful details (technical or marketing). Synergy comes to mind as a good example. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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. ___ 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.
[time-nuts] help with initial setup for Motorola M12+T GPS? is my board dead?
I just received my first real piece of time hardware, a M12+T timing GPS. At least, that's what it's supposed to be, it doesn't actually have any label saying so. I got it online from this seller: http://www.ioffer.com/i/Motorola-ONCORE-M12+T-timing-gps-receiver-1pps-100hz-105387652 The board I received looks like this: https://picasaweb.google.com/bealevideo/GPS#5580118907079326290 I got the 2x5 0.05 connector, built a 3.0V power supply, and hooked up the serial lines to a FTDI USB-to-serial (3.3V logic level) board, and am trying to talk Motorola Binary at 9600 baud to it using WinOncore12. I tried the setup receiver wizard, the GPS self-test, and uploading an almanac. My scope shows the serial data from the PC going into the board, but no signals ever come out. The TX line out of the board just sits quietly at +3V. Is there anything obvious I should be trying? Thanks for any help! ___ 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.
