Re: [time-nuts] Garmin 255W GPS units
Hi They are fairly standard navigation receivers. The data they put out is also fairly standard. Based on my experience with flood damaged electronics, your estimate for working units may be a bit high if they were under long enough to get well soaked. Bob On Aug 4, 2010, at 1:04 AM, jim stephens wrote: I have access to a large number of these units (~600). We are in the process of scanning them for functional units. They are 4 dashtop type car or boat units. I have played with a functional one, and accessed some info with free software, and would of course like to get to the actual live position. I am open to any ideas from anyone who would like the units which are not working for parts. It appears that the units which have functional internals, but no display may be as many as 100 total. Hopefully no more than 50% will be dead, and parts only, but it may go as high as 75%. These units appear to have spent time submerged as far as the damage sustained. They are purchased from an insurance salvage situation. I have managed to dismantle them down to a housing set, battery, processor board, display assembly, and misc. hardware. Please contact me at jwsmobile [at] g[m] ail.com (removing special characters). Thanks Jim ___ 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] What's the latest correct PICTIC II Mouser project?
I've ordered the mouser project and skipped the parts that won't ship until 2011. So we're in the same boat. Leigh/Wa5ZNU ___ 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] Buffer / distribution amplifier for TCXO
Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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] Garmin 255W GPS units
fi they are like 265's you can run them in Fleet mode and that can get you positional updates something like once a second. a goal of mine with the 265W I have in the truck once I come across a cheap Linux PC in a can that runs off 12V -pete On Tue, Aug 3, 2010 at 10:04 PM, jim stephens jwsmob...@gmail.com wrote: I have access to a large number of these units (~600). We are in the process of scanning them for functional units. They are 4 dashtop type car or boat units. I have played with a functional one, and accessed some info with free software, and would of course like to get to the actual live position. I am open to any ideas from anyone who would like the units which are not working for parts. It appears that the units which have functional internals, but no display may be as many as 100 total. Hopefully no more than 50% will be dead, and parts only, but it may go as high as 75%. These units appear to have spent time submerged as far as the damage sustained. They are purchased from an insurance salvage situation. I have managed to dismantle them down to a housing set, battery, processor board, display assembly, and misc. hardware. Please contact me at jwsmobile [at] g[m] ail.com (removing special characters). Thanks Jim ___ 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] Buffer / distribution amplifier for TCXO
Henry Hallam wrote: Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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. The TCXO output waveform is presumably a clipped sinewave as required by the SE4120L? In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Bruce ___ 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] Buffer / distribution amplifier for TCXO
Hi I suspect you will find that the phase noise floor of the distribution system does indeed matter. Likely the easy way to go: Square the TCXO up with a biased CMOS inverter (at least as fast as a 74AC04). Run a seperate inverter to drive each of the receivers. A hex inverter chip would do it all quite nicely. There should be plenty of isolation and far more signal than is needed. Attenuating it at the receiver with a pair of resistors should get all the levels to match up. If you want to get fancy, transformer couple into each receiver after attenuating. Bob -- From: Henry Hallam he...@pericynthion.org Sent: Wednesday, August 04, 2010 1:46 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Buffer / distribution amplifier for TCXO Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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] Buffer / distribution amplifier for TCXO
On Wed, Aug 4, 2010 at 1:50 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: The TCXO output waveform is presumably a clipped sinewave as required by the SE4120L? I posted the waveform at http://www.pericynthion.org/stuff/KT3225_500mV_per_div.jpg Does that count as clipped sine? If not, it seems to work anyway. In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. I'm making a custom board that will include the TCXO and distribution amplifier (as well as some digital stuff to allow the 4 receivers to communicate), so it can have whatever power supplies it needs. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Thanks. Henry ___ 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] What's the latest correct PICTIC II Mouser project?
If there are multiple Mouser projects... which one is best (least backordered parts) and highest quality parts? Please send a link. Thank you in advance. Has anyone started updating the project to include substitutes? 73 Brice KA8MAV - Original Message - From: Leigh L. Klotz, Jr. WA5ZNU le...@wa5znu.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, August 04, 2010 1:16 PM Subject: Re: [time-nuts] What's the latest correct PICTIC II Mouser project? I've ordered the mouser project and skipped the parts that won't ship until 2011. So we're in the same boat. Leigh/Wa5ZNU ___ 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] Buffer / distribution amplifier for TCXO
The GPS receiver chip actually specifies that a clipped sinewave should be used. Presumably this is necessary to limit the harmonic contents. In which case low pass filtering the CMOS outputs may be necessary. The 74AHC04 or equivalent may be a better choice as its ground and Vcc bounce is lower than that of a 74AC04. Bruce Bob Camp wrote: Hi I suspect you will find that the phase noise floor of the distribution system does indeed matter. Likely the easy way to go: Square the TCXO up with a biased CMOS inverter (at least as fast as a 74AC04). Run a seperate inverter to drive each of the receivers. A hex inverter chip would do it all quite nicely. There should be plenty of isolation and far more signal than is needed. Attenuating it at the receiver with a pair of resistors should get all the levels to match up. If you want to get fancy, transformer couple into each receiver after attenuating. Bob -- From: Henry Hallam he...@pericynthion.org Sent: Wednesday, August 04, 2010 1:46 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Buffer / distribution amplifier for TCXO Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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] Buffer / distribution amplifier for TCXO
Henry Hallam wrote: On Wed, Aug 4, 2010 at 1:50 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: The TCXO output waveform is presumably a clipped sinewave as required by the SE4120L? I posted the waveform at http://www.pericynthion.org/stuff/KT3225_500mV_per_div.jpg Does that count as clipped sine? If not, it seems to work anyway. Its something like a clipped sine albeit with some ringing as it is clipped. It more closely resembles a low pass filtered square wave. In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. I'm making a custom board that will include the TCXO and distribution amplifier (as well as some digital stuff to allow the 4 receivers to communicate), so it can have whatever power supplies it needs. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Thanks. Henry Bruce ___ 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] Buffer / distribution amplifier for TCXO
Hi The phase noise floor of the HC is *much* higher than the floor of the AC gates. The main reason it specifies clipped sine is that's what the cheap TCXO's put out. Bob On Aug 4, 2010, at 6:42 PM, Bruce Griffiths wrote: The GPS receiver chip actually specifies that a clipped sinewave should be used. Presumably this is necessary to limit the harmonic contents. In which case low pass filtering the CMOS outputs may be necessary. The 74AHC04 or equivalent may be a better choice as its ground and Vcc bounce is lower than that of a 74AC04. Bruce Bob Camp wrote: Hi I suspect you will find that the phase noise floor of the distribution system does indeed matter. Likely the easy way to go: Square the TCXO up with a biased CMOS inverter (at least as fast as a 74AC04). Run a seperate inverter to drive each of the receivers. A hex inverter chip would do it all quite nicely. There should be plenty of isolation and far more signal than is needed. Attenuating it at the receiver with a pair of resistors should get all the levels to match up. If you want to get fancy, transformer couple into each receiver after attenuating. Bob -- From: Henry Hallam he...@pericynthion.org Sent: Wednesday, August 04, 2010 1:46 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Buffer / distribution amplifier for TCXO Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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] Buffer / distribution amplifier for TCXO
Is that also true for AHC devices which otherwise have similar characteristics (apart from ground bounce) to AC devices? Bruce Bob Camp wrote: Hi The phase noise floor of the HC is *much* higher than the floor of the AC gates. The main reason it specifies clipped sine is that's what the cheap TCXO's put out. Bob On Aug 4, 2010, at 6:42 PM, Bruce Griffiths wrote: The GPS receiver chip actually specifies that a clipped sinewave should be used. Presumably this is necessary to limit the harmonic contents. In which case low pass filtering the CMOS outputs may be necessary. The 74AHC04 or equivalent may be a better choice as its ground and Vcc bounce is lower than that of a 74AC04. Bruce Bob Camp wrote: Hi I suspect you will find that the phase noise floor of the distribution system does indeed matter. Likely the easy way to go: Square the TCXO up with a biased CMOS inverter (at least as fast as a 74AC04). Run a seperate inverter to drive each of the receivers. A hex inverter chip would do it all quite nicely. There should be plenty of isolation and far more signal than is needed. Attenuating it at the receiver with a pair of resistors should get all the levels to match up. If you want to get fancy, transformer couple into each receiver after attenuating. Bob -- From: Henry Hallamhe...@pericynthion.org Sent: Wednesday, August 04, 2010 1:46 PM To: Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: [time-nuts] Buffer / distribution amplifier for TCXO Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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] Buffer / distribution amplifier for TCXO
Bruce Griffiths wrote: In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Bruce A more efficient buffer amplifier circuit schematic is attached. The series transformer feedback stage has high input impedance and an output impedance matched to the transmission line (yes it works well with long transmission lines as well). However a trifilar wound RF transformer is required. In principle the various GPS receivers could be connected to taps along an end terminated transmission line using feedthrough connections with compensation for the tap shunt capacitance if necessary. A lower impedance line (eg 50 ohms) could also be driven at the expense of a higher collector current. In this case the value of R3 would need to be reduced to around 100 ohms or so. Bruce attachment: TCXO_BUFFER.gif___ 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] Buffer / distribution amplifier for TCXO
Hi It's a speed thing. The faster silicon based CMOS is , the quieter it seems to be. Bob On Aug 4, 2010, at 8:21 PM, Bruce Griffiths wrote: Is that also true for AHC devices which otherwise have similar characteristics (apart from ground bounce) to AC devices? Bruce Bob Camp wrote: Hi The phase noise floor of the HC is *much* higher than the floor of the AC gates. The main reason it specifies clipped sine is that's what the cheap TCXO's put out. Bob On Aug 4, 2010, at 6:42 PM, Bruce Griffiths wrote: The GPS receiver chip actually specifies that a clipped sinewave should be used. Presumably this is necessary to limit the harmonic contents. In which case low pass filtering the CMOS outputs may be necessary. The 74AHC04 or equivalent may be a better choice as its ground and Vcc bounce is lower than that of a 74AC04. Bruce Bob Camp wrote: Hi I suspect you will find that the phase noise floor of the distribution system does indeed matter. Likely the easy way to go: Square the TCXO up with a biased CMOS inverter (at least as fast as a 74AC04). Run a seperate inverter to drive each of the receivers. A hex inverter chip would do it all quite nicely. There should be plenty of isolation and far more signal than is needed. Attenuating it at the receiver with a pair of resistors should get all the levels to match up. If you want to get fancy, transformer couple into each receiver after attenuating. Bob -- From: Henry Hallamhe...@pericynthion.org Sent: Wednesday, August 04, 2010 1:46 PM To: Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: [time-nuts] Buffer / distribution amplifier for TCXO Dear time nuts, Background: I have built a GPS receiver based around the SE4120L front end IC [1]. I used a KT3225 TCXO [2] at 16.3676MHz driving the front end through a 10nF series capacitor as in the example circuit in [1]. Inside the front end, this oscillator is multiplied up to form a local oscillator at 1571.2896 MHz. The 16.3676MHz signal is also divided to form a 4.0919MHz sampling clock. Digital I and Q samples then go to a DSP where the GPS signal processing is done in software. My receiver works nicely, getting it online was a boatload of fun and I'm hoping to make it available soon along with open-source software as a GPS experimenter's kit. Problem: I'd like to clock multiple receivers from a single 16.3676MHz oscillator, in order to combine measurements from multiple antennas. The clocks must be at the same frequency, i.e. from the same source, but it is not necessary that they have any particular phase relationship as phase offsets are removed in the navigation processing. What sort of distribution amplifier should I use to split the output of one TCXO into four front ends? Do I need some kind of impedance matching network? How would I go about designing that? This sort of analog/RF design is unfamiliar territory for me, though I'd like to learn. The TCXO advertises a minimum output level of 0.8Vpp into (10kohm in parallel with 10pF). The front end requires a minimum oscillator drive level of 0.2Vpp. The front end datasheet lists recommended crystal parameters including a load capacitance of 10pF (typ), although I don't know whether or not that refers to the front end input capacitance. My guess is that phase noise performance is not particularly crucial, at least by time-nuts standards. I guess it would be nice if the amplifier didn't make the phase noise significantly worse than it already is from the cheap TCXO. Many thanks, Henry Hallam [1] http://www.sige.com/support/download-form.html?dl=DST-00059_SE4120L_Datasheet_Rev_3p5_CYW_May-26-2009.pdf [2] http://global.kyocera.com/prdct/electro/pdf/tcxo/172_e.pdf ___ 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
Re: [time-nuts] buffer amp transformers...
I think I'm a time-nut; as symptoms I include (1) a lot of Mini-Circuits parts on my bench, (2) searches on eBay for Mini-Circuits goodies, and (3) the desire to know how my LPRO, 10811, and Thunderbolt are different, and how much better a Thunderbolt would be with a 10811 double-oven in it... Anyway, here's an eBay auction for 25 T-626 1:1:1 transformers -- item number: 220544907085 http://cgi.ebay.com/25-Mini-Circuits-T-626-RF-Transformers-0-01-10-MHz-/220544907085?cmd=ViewItempt=LH_DefaultDomain_0hash=item335980374d which look like just the thing for this amp... 73 de bob k6rtm in silicon valley - Message: 4 Date: Thu, 05 Aug 2010 10:05:39 +1200 From: Bruce Griffiths bruce.griffi...@xtra.co.nz Subject: Re: [time-nuts] Buffer / distribution amplifier for TCXO To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 4c59e433.6000...@xtra.co.nz Content-Type: text/plain; charset=iso-8859-1; Format=flowed Bruce Griffiths wrote: In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Bruce A more efficient buffer amplifier circuit schematic is attached. The series transformer feedback stage has high input impedance and an output impedance matched to the transmission line (yes it works well with long transmission lines as well). However a trifilar wound RF transformer is required. In principle the various GPS receivers could be connected to taps along an end terminated transmission line using feedthrough connections with compensation for the tap shunt capacitance if necessary. A lower impedance line (eg 50 ohms) could also be driven at the expense of a higher collector current. In this case the value of R3 would need to be reduced to around 100 ohms or so. Bruce -- next part -- A non-text attachment was scrubbed... Name: TCXO_BUFFER.gif Type: image/gif Size: 7990 bytes Desc: not available URL: http://www.febo.com/pipermail/time-nuts/attachments/20100805/091e6a74/attachment.gif -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 73, Issue 12 * ___ 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] buffer amp transformers...
The spec sheet lists them as being good to 10MHz; would they be ok at 16MHz with a little more loss, or should I worry about resonances with parasitic capacitance? 73 de Henry M0HMH in Santa Cruz On Wed, Aug 4, 2010 at 9:14 PM, k6...@comcast.net wrote: I think I'm a time-nut; as symptoms I include (1) a lot of Mini-Circuits parts on my bench, (2) searches on eBay for Mini-Circuits goodies, and (3) the desire to know how my LPRO, 10811, and Thunderbolt are different, and how much better a Thunderbolt would be with a 10811 double-oven in it... Anyway, here's an eBay auction for 25 T-626 1:1:1 transformers -- item number: 220544907085 http://cgi.ebay.com/25-Mini-Circuits-T-626-RF-Transformers-0-01-10-MHz-/220544907085?cmd=ViewItempt=LH_DefaultDomain_0hash=item335980374d which look like just the thing for this amp... 73 de bob k6rtm in silicon valley - Message: 4 Date: Thu, 05 Aug 2010 10:05:39 +1200 From: Bruce Griffiths bruce.griffi...@xtra.co.nz Subject: Re: [time-nuts] Buffer / distribution amplifier for TCXO To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 4c59e433.6000...@xtra.co.nz Content-Type: text/plain; charset=iso-8859-1; Format=flowed Bruce Griffiths wrote: In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Bruce A more efficient buffer amplifier circuit schematic is attached. The series transformer feedback stage has high input impedance and an output impedance matched to the transmission line (yes it works well with long transmission lines as well). However a trifilar wound RF transformer is required. In principle the various GPS receivers could be connected to taps along an end terminated transmission line using feedthrough connections with compensation for the tap shunt capacitance if necessary. A lower impedance line (eg 50 ohms) could also be driven at the expense of a higher collector current. In this case the value of R3 would need to be reduced to around 100 ohms or so. Bruce -- next part -- A non-text attachment was scrubbed... Name: TCXO_BUFFER.gif Type: image/gif Size: 7990 bytes Desc: not available URL: http://www.febo.com/pipermail/time-nuts/attachments/20100805/091e6a74/attachment.gif -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 73, Issue 12 * ___ 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. -- Henry Hallam Sent from my Laptop ___ 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] buffer amp transformers...
For this application you'll need a bandwidth of somewhat more than 10MHz to preserve the clock slew rate. Those transformers are better suited to sinewave operation at 5 or 10MHz. If one uses a pair of transformers (one for the feedback and one to isolate the output) then wider bandwidth 1:1 transformers can be used. Or one could just elect to capacitively couple the load. Alternatively one can just wind one's own trifilar transformer using a suitable binocular ferrite core. Bruce Henry Hallam wrote: The spec sheet lists them as being good to 10MHz; would they be ok at 16MHz with a little more loss, or should I worry about resonances with parasitic capacitance? 73 de Henry M0HMH in Santa Cruz On Wed, Aug 4, 2010 at 9:14 PM,k6...@comcast.net wrote: I think I'm a time-nut; as symptoms I include (1) a lot of Mini-Circuits parts on my bench, (2) searches on eBay for Mini-Circuits goodies, and (3) the desire to know how my LPRO, 10811, and Thunderbolt are different, and how much better a Thunderbolt would be with a 10811 double-oven in it... Anyway, here's an eBay auction for 25 T-626 1:1:1 transformers -- item number: 220544907085 http://cgi.ebay.com/25-Mini-Circuits-T-626-RF-Transformers-0-01-10-MHz-/220544907085?cmd=ViewItempt=LH_DefaultDomain_0hash=item335980374d which look like just the thing for this amp... 73 de bob k6rtm in silicon valley - Message: 4 Date: Thu, 05 Aug 2010 10:05:39 +1200 From: Bruce Griffithsbruce.griffi...@xtra.co.nz Subject: Re: [time-nuts] Buffer / distribution amplifier for TCXO To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID:4c59e433.6000...@xtra.co.nz Content-Type: text/plain; charset=iso-8859-1; Format=flowed Bruce Griffiths wrote: In which case a linear distribution amplifier is probably required. With only a ~3V supply available, options for the distribution amplifier topology are somewhat limited. In principle you could use an emitter follower driving 4 other emitter followers with a resistor in series with the emitters of the output devices and the AC coupled loads to match the source to the interconnecting cable impedance to minimise reflections without requiring excessive dissipation in the emitter followers. With the low voltage supply available, using an RF choke is series with the emitter follower's emitter to ground resistor will also be useful in achieving the required dynamic range. Bruce A more efficient buffer amplifier circuit schematic is attached. The series transformer feedback stage has high input impedance and an output impedance matched to the transmission line (yes it works well with long transmission lines as well). However a trifilar wound RF transformer is required. In principle the various GPS receivers could be connected to taps along an end terminated transmission line using feedthrough connections with compensation for the tap shunt capacitance if necessary. A lower impedance line (eg 50 ohms) could also be driven at the expense of a higher collector current. In this case the value of R3 would need to be reduced to around 100 ohms or so. Bruce -- next part -- A non-text attachment was scrubbed... Name: TCXO_BUFFER.gif Type: image/gif Size: 7990 bytes Desc: not available URL:http://www.febo.com/pipermail/time-nuts/attachments/20100805/091e6a74/attachment.gif -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 73, Issue 12 * ___ 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.
