Guys, Thanks for all the advice. I'll let you know how it goes...
Steve On 23 July 2012 18:06, <[email protected]> wrote: > Send time-nuts mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > > 1. Re: Zero-Crossing Detector Design? (ct1dmk) > 2. Trimble T Lassen 2 - suitable antenna....advice.....questions > (Stephen Farthing) > 3. Re: Trimble T Lassen 2 - > suitableantenna....advice.....questions (jmfranke) > 4. Re: Trimble T Lassen 2 - > suitableantenna....advice.....questions (Azelio Boriani) > 5. Re: Trimble T Lassen 2 - > suitableantenna....advice.....questions (Chris Albertson) > 6. Re: Trimble T Lassen 2 - > suitableantenna....advice.....questions (Bob Bownes) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 23 Jul 2012 13:37:25 +0100 > From: ct1dmk <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: Re: [time-nuts] Zero-Crossing Detector Design? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi Bob, > > No, never tried but it looks a good idea. > Our boards all have 5v so there was never any pressure... > > ... for a 0.5v in the tail resistor to vcc and 0.7v of vbe > I could easily allow collectors to swing some 300mv around 1.2V... > > a couple of resistors more than my single ended solution... > but it should work fine from 3v3. Must try that. tks, > > lc > ct1dmk, > > > > > On 7/23/2012 12:35 PM, Bob Camp wrote: >> Hi >> >> Did you try running it at 3.3V and going into an LVDS input on the FPGA? >> >> Bob >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On >> Behalf Of ct1dmk >> Sent: Monday, July 23, 2012 7:26 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Zero-Crossing Detector Design? >> >> For the specific application of driving an FPGA clock pin (that has an >> enormous input bandwidth) many things can go wrong. >> All fine about the advantages and disadvantages of >> the gate with resistor feedback, all I can say is that over here I it >> was not the best solution >> we found over many FPGA board versions with external clock. >> The latest design and the one we keep using standard now, uses a >> differential pair of PNP >> transistors (BFT91), this will have a moderate gain of x10 or so and the >> resistors set >> for making a limited wave of 0 to 3.0V (simple change of resistors can >> make it 0-2.0V >> or else required). we use a 100MHz narrow band limited bandwidth sin >> signal so no filter >> added, but we could add if we need one. >> The output signal into the FPGA looks very clean and has a few ns rise >> and fall times >> (not super steep, but the fpga input does the rest. It does depend also >> on the resistor values and current used in the transistor pair). >> This was the way we could get the very minimum clock jitter in the FPGA >> and a >> simple circuit quite tolerant to input levels and make a very clean and >> well defined signal >> into the FPGA. Way better than 74F or 74LV gates etc. >> The only inconvenience is that it needs +5V for the circuit to work (the >> VCCIO of +3.3V is not enough). >> >> My 2 euro cents ;-) >> >> Luis Cupido >> ct1dmk. >> >> >> On 7/22/2012 9:32 PM, Bill Fuqua wrote: >>> Wow, I have not checked this list for some time. But there is a lot said >>> about zero crossing detectors. >>> Lots and lots of replies, so many that I have not looked at all of them. >>> 1. Do not use CMOS inverters. Even though so much has been published on >>> using these in linear mode by >>> adding a feedback resistor, they can be a nightmare. The fast ones >>> (74HC, 74AC, etc) have so much high frequency gain they are >>> likely to take off into oscillation on their own. >>> 2. The first thing you can do to get a good clean zero crossing is to >>> reduce the noise. This means to pass it >>> thru a narrow band pass filter such as a crystal filter. The narrower >>> this filter is the closer to a pure sinewave it becomes >>> and the less noise you have. >>> 3. In research when we want a precise trigger we use what is called a >>> constant fraction discriminator. >>> This may not be needed if you have a very clean signal and its amplitude >>> does not vary and you are wanting to >>> trigger exactly at zero. But a constant fraction discriminator triggers >>> on a point that is a constant fraction of the >>> amplitude of the signal. They require a delay so that a fraction of the >>> peak of the cycle can be compared with the rising edge >>> of that cycle. This is mostly used with triggering on pulses of varying >>> heights and when subnanosecond >>> timing is required. >>> >>> My suggestion is to clean up your signal as much as possible and reduce >>> noise bandwidth using a bandpass filter and >>> then use a low noise amplifier for the front end of your zero-crossing >>> detector. >>> >>> 73 >>> Bill wa4lav >>> >>> >>> >>> _______________________________________________ >>> 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. >> >> >> _______________________________________________ >> 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. >> > > > > ------------------------------ > > Message: 2 > Date: Mon, 23 Jul 2012 17:11:43 +0100 > From: Stephen Farthing <[email protected]> > To: [email protected] > Subject: [time-nuts] Trimble T Lassen 2 - suitable > antenna....advice.....questions > Message-ID: > <caax2mdlgupho9cgarwua6f-_z5tqlo74_pkmz0k9frajs0s...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi Guys, > > I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - > the guy told me they were left over from a contract he had and were > brand new. He had a load and i bought a couple for use as a precision > 1 PPS output for radio stuff. They were packed in static protection. > When I apply power to both units I can hear the oscillator (12.504 > MHz) on my comms RX. So I am assuming that they work. > > I bought what claims to be a Trimble compatible active antenna on > EBay. I hooked it up to one of the boards and applied power, and put > the scope on the one pps pin. However after 20 mins (which I assume is > much longer than the unit requires to get a lock) I see no 1pps trace > on the screen. :-( > > So my working assumption is that the antenna is not working. The > antenna position is fine as my elderly Garmin GPS2 which must be 12 > years old sees 6 satellites there. > > Can anyone recommend a suitable antenna? I have a number of DIY > designs I can try (Patch, Turnstile) but the Trimble docs say it needs > an active antenna so I guess I'll have to spend money :-( > > While i am on, can anyone suggest a reasonably priced unit that has a > 1pps output, NMEA and a built in antenna. Because I want to use this > with an 8 bit embedded system I am probably not going to be able to > hack one of the many cheap USB dongle GPS's. > > Lastly, has anyone found a GPS that will work with an Ipad. What the > man in the Apple shop failed to tell me was the non 3g model lacked > the built in GPS :-( > > Thanks in advice.... > > Steve > > > > -- > Wisdom demands a new orientation of science and technology towards the > organic, the gentle, the non-violent, the elegant and beautiful. E. F. > Schumacher > > > > ------------------------------ > > Message: 3 > Date: Mon, 23 Jul 2012 12:31:35 -0400 > From: "jmfranke" <[email protected]> > To: <[email protected]> > Subject: Re: [time-nuts] Trimble T Lassen 2 - > suitableantenna....advice.....questions > Message-ID: <EC471E64A1EF401A8AFBC83E8BC402C3@Franke> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > Do not be too quick to toss out the antennas. Some receivers need the > antenna power to be connected to a pin on the receiver connector that is > then internally routed to the antenna. > > John WA4WDL > > -------------------------------------------------- > From: "Stephen Farthing" <[email protected]> > Sent: Monday, July 23, 2012 12:11 PM > To: <[email protected]> > Subject: [time-nuts] Trimble T Lassen 2 - > suitableantenna....advice.....questions > >> Hi Guys, >> >> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >> the guy told me they were left over from a contract he had and were >> brand new. He had a load and i bought a couple for use as a precision >> 1 PPS output for radio stuff. They were packed in static protection. >> When I apply power to both units I can hear the oscillator (12.504 >> MHz) on my comms RX. So I am assuming that they work. >> >> I bought what claims to be a Trimble compatible active antenna on >> EBay. I hooked it up to one of the boards and applied power, and put >> the scope on the one pps pin. However after 20 mins (which I assume is >> much longer than the unit requires to get a lock) I see no 1pps trace >> on the screen. :-( >> >> So my working assumption is that the antenna is not working. The >> antenna position is fine as my elderly Garmin GPS2 which must be 12 >> years old sees 6 satellites there. >> >> Can anyone recommend a suitable antenna? I have a number of DIY >> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >> an active antenna so I guess I'll have to spend money :-( >> >> While i am on, can anyone suggest a reasonably priced unit that has a >> 1pps output, NMEA and a built in antenna. Because I want to use this >> with an 8 bit embedded system I am probably not going to be able to >> hack one of the many cheap USB dongle GPS's. >> >> Lastly, has anyone found a GPS that will work with an Ipad. What the >> man in the Apple shop failed to tell me was the non 3g model lacked >> the built in GPS :-( >> >> Thanks in advice.... >> >> Steve >> >> >> >> -- >> Wisdom demands a new orientation of science and technology towards the >> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >> Schumacher >> >> _______________________________________________ >> 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. >> > > > > > ------------------------------ > > Message: 4 > Date: Mon, 23 Jul 2012 18:49:33 +0200 > From: Azelio Boriani <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: Re: [time-nuts] Trimble T Lassen 2 - > suitableantenna....advice.....questions > Message-ID: > <cal8xpmp6k8j7ouwkkiyn1_0gp4yr-90xzt1vr6nc6hw2dxy...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > ...And don't forget that the PPS pulse is very narrow so you have to use a > 'scope with memory, a digital 'scope or turn the brightness at max. > > On Mon, Jul 23, 2012 at 6:31 PM, jmfranke <[email protected]> wrote: > >> Do not be too quick to toss out the antennas. Some receivers need the >> antenna power to be connected to a pin on the receiver connector that is >> then internally routed to the antenna. >> >> John WA4WDL >> >> -------------------------------------------------- >> From: "Stephen Farthing" <[email protected]> >> Sent: Monday, July 23, 2012 12:11 PM >> To: <[email protected]> >> Subject: [time-nuts] Trimble T Lassen 2 - >> suitableantenna....advice.....questions >> >> >> Hi Guys, >>> >>> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >>> the guy told me they were left over from a contract he had and were >>> brand new. He had a load and i bought a couple for use as a precision >>> 1 PPS output for radio stuff. They were packed in static protection. >>> When I apply power to both units I can hear the oscillator (12.504 >>> MHz) on my comms RX. So I am assuming that they work. >>> >>> I bought what claims to be a Trimble compatible active antenna on >>> EBay. I hooked it up to one of the boards and applied power, and put >>> the scope on the one pps pin. However after 20 mins (which I assume is >>> much longer than the unit requires to get a lock) I see no 1pps trace >>> on the screen. :-( >>> >>> So my working assumption is that the antenna is not working. The >>> antenna position is fine as my elderly Garmin GPS2 which must be 12 >>> years old sees 6 satellites there. >>> >>> Can anyone recommend a suitable antenna? I have a number of DIY >>> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >>> an active antenna so I guess I'll have to spend money :-( >>> >>> While i am on, can anyone suggest a reasonably priced unit that has a >>> 1pps output, NMEA and a built in antenna. Because I want to use this >>> with an 8 bit embedded system I am probably not going to be able to >>> hack one of the many cheap USB dongle GPS's. >>> >>> Lastly, has anyone found a GPS that will work with an Ipad. What the >>> man in the Apple shop failed to tell me was the non 3g model lacked >>> the built in GPS :-( >>> >>> Thanks in advice.... >>> >>> Steve >>> >>> >>> >>> -- >>> Wisdom demands a new orientation of science and technology towards the >>> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >>> Schumacher >>> >>> _______________________________________________ >>> 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. >> > > > ------------------------------ > > Message: 5 > Date: Mon, 23 Jul 2012 09:58:40 -0700 > From: Chris Albertson <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: Re: [time-nuts] Trimble T Lassen 2 - > suitableantenna....advice.....questions > Message-ID: > <cabbxvhv_5wsutdboh4e7t_wv7v418ulejmkxnbzts54pywt...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > I wass fooled by this too. My analog scope does not sync on athe1Hz > pulse. You have to breadboard something that will detect it, maybe a > flip flop and then look at the FF's output. > > On Mon, Jul 23, 2012 at 9:49 AM, Azelio Boriani > <[email protected]> wrote: >> ...And don't forget that the PPS pulse is very narrow so you have to use a >> 'scope with memory, a digital 'scope or turn the brightness at max. >> >> On Mon, Jul 23, 2012 at 6:31 PM, jmfranke <[email protected]> wrote: >> >>> Do not be too quick to toss out the antennas. Some receivers need the >>> antenna power to be connected to a pin on the receiver connector that is >>> then internally routed to the antenna. >>> >>> John WA4WDL >>> >>> -------------------------------------------------- >>> From: "Stephen Farthing" <[email protected]> >>> Sent: Monday, July 23, 2012 12:11 PM >>> To: <[email protected]> >>> Subject: [time-nuts] Trimble T Lassen 2 - >>> suitableantenna....advice.....questions >>> >>> >>> Hi Guys, >>>> >>>> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >>>> the guy told me they were left over from a contract he had and were >>>> brand new. He had a load and i bought a couple for use as a precision >>>> 1 PPS output for radio stuff. They were packed in static protection. >>>> When I apply power to both units I can hear the oscillator (12.504 >>>> MHz) on my comms RX. So I am assuming that they work. >>>> >>>> I bought what claims to be a Trimble compatible active antenna on >>>> EBay. I hooked it up to one of the boards and applied power, and put >>>> the scope on the one pps pin. However after 20 mins (which I assume is >>>> much longer than the unit requires to get a lock) I see no 1pps trace >>>> on the screen. :-( >>>> >>>> So my working assumption is that the antenna is not working. The >>>> antenna position is fine as my elderly Garmin GPS2 which must be 12 >>>> years old sees 6 satellites there. >>>> >>>> Can anyone recommend a suitable antenna? I have a number of DIY >>>> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >>>> an active antenna so I guess I'll have to spend money :-( >>>> >>>> While i am on, can anyone suggest a reasonably priced unit that has a >>>> 1pps output, NMEA and a built in antenna. Because I want to use this >>>> with an 8 bit embedded system I am probably not going to be able to >>>> hack one of the many cheap USB dongle GPS's. >>>> >>>> Lastly, has anyone found a GPS that will work with an Ipad. What the >>>> man in the Apple shop failed to tell me was the non 3g model lacked >>>> the built in GPS :-( >>>> >>>> Thanks in advice.... >>>> >>>> Steve >>>> >>>> >>>> >>>> -- >>>> Wisdom demands a new orientation of science and technology towards the >>>> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >>>> Schumacher >>>> >>>> _______________________________________________ >>>> 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. >>> >> _______________________________________________ >> 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. > > > > -- > > Chris Albertson > Redondo Beach, California > > > > ------------------------------ > > Message: 6 > Date: Mon, 23 Jul 2012 13:05:49 -0400 > From: Bob Bownes <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: Re: [time-nuts] Trimble T Lassen 2 - > suitableantenna....advice.....questions > Message-ID: > <CACsYtUt=atuz3gqx-itv4myrncsfhmtancjuf9gyaiz5q60...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > The pulse from my T-Bolt is on the order of 1uS wide. I captured it on the > digital scope for posterity and future reference. > > http://www.fastbobs.com/pictures/1pps.jpg > > Bob > > > On Mon, Jul 23, 2012 at 12:58 PM, Chris Albertson <[email protected] >> wrote: > >> I wass fooled by this too. My analog scope does not sync on athe1Hz >> pulse. You have to breadboard something that will detect it, maybe a >> flip flop and then look at the FF's output. >> >> On Mon, Jul 23, 2012 at 9:49 AM, Azelio Boriani >> <[email protected]> wrote: >> > ...And don't forget that the PPS pulse is very narrow so you have to use >> a >> > 'scope with memory, a digital 'scope or turn the brightness at max. >> > >> > On Mon, Jul 23, 2012 at 6:31 PM, jmfranke <[email protected]> wrote: >> > >> >> Do not be too quick to toss out the antennas. Some receivers need the >> >> antenna power to be connected to a pin on the receiver connector that is >> >> then internally routed to the antenna. >> >> >> >> John WA4WDL >> >> >> >> -------------------------------------------------- >> >> From: "Stephen Farthing" <[email protected]> >> >> Sent: Monday, July 23, 2012 12:11 PM >> >> To: <[email protected]> >> >> Subject: [time-nuts] Trimble T Lassen 2 - >> >> suitableantenna....advice.....questions >> >> >> >> >> >> Hi Guys, >> >>> >> >>> I have a couple of Trimble T Lassen 2 boards I bought at a Hamfest - >> >>> the guy told me they were left over from a contract he had and were >> >>> brand new. He had a load and i bought a couple for use as a precision >> >>> 1 PPS output for radio stuff. They were packed in static protection. >> >>> When I apply power to both units I can hear the oscillator (12.504 >> >>> MHz) on my comms RX. So I am assuming that they work. >> >>> >> >>> I bought what claims to be a Trimble compatible active antenna on >> >>> EBay. I hooked it up to one of the boards and applied power, and put >> >>> the scope on the one pps pin. However after 20 mins (which I assume is >> >>> much longer than the unit requires to get a lock) I see no 1pps trace >> >>> on the screen. :-( >> >>> >> >>> So my working assumption is that the antenna is not working. The >> >>> antenna position is fine as my elderly Garmin GPS2 which must be 12 >> >>> years old sees 6 satellites there. >> >>> >> >>> Can anyone recommend a suitable antenna? I have a number of DIY >> >>> designs I can try (Patch, Turnstile) but the Trimble docs say it needs >> >>> an active antenna so I guess I'll have to spend money :-( >> >>> >> >>> While i am on, can anyone suggest a reasonably priced unit that has a >> >>> 1pps output, NMEA and a built in antenna. Because I want to use this >> >>> with an 8 bit embedded system I am probably not going to be able to >> >>> hack one of the many cheap USB dongle GPS's. >> >>> >> >>> Lastly, has anyone found a GPS that will work with an Ipad. What the >> >>> man in the Apple shop failed to tell me was the non 3g model lacked >> >>> the built in GPS :-( >> >>> >> >>> Thanks in advice.... >> >>> >> >>> Steve >> >>> >> >>> >> >>> >> >>> -- >> >>> Wisdom demands a new orientation of science and technology towards the >> >>> organic, the gentle, the non-violent, the elegant and beautiful. E. F. >> >>> Schumacher >> >>> >> >>> _______________________________________________ >> >>> 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. >> >> >> > _______________________________________________ >> > 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. >> >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> >> _______________________________________________ >> 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] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > End of time-nuts Digest, Vol 96, Issue 89 > ***************************************** -- Wisdom demands a new orientation of science and technology towards the organic, the gentle, the non-violent, the elegant and beautiful. E. F. Schumacher _______________________________________________ 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.
