Re: [time-nuts] Need tiny 5MHz 10x amplifier
Poul-Henning wrote: I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V CMOS compatible logic signal. The "default" comparator based circuit either requires a negative supply or 4 resitors for biasing the input and setting the zero level. (The hysteresis resistor is the same in both cases). The LT1720** works on a 3.3v single supply, and has internal hysteresis. Just ground one input, ground the other through a resistor, and attach your AC-coupled signal (best if you can use equal resistors to ground on the two inputs, but if the signal termination is 50 ohms the other input can be 0 ohms to ground; even 1k ohm would probably be OK). Note that the LT1720 is specified for inputs to 100mV below V- (ground, in this case) and your 200mVpp signal pushes it right to the limit. A bit of attenuation is probably a good idea. ** The 1720 is a dual comparator, so you'd have an extra to use or ignore. Alternatively, the 1719 is a single with extra features that you could ignore. Either should work well in your application. 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] Need tiny 5MHz 10x amplifier
On Sun, 29 Nov 2015 00:35:31 + Poul-Henning Kamp wrote: > Since space is a bit tight, I've been trying to find something like > a "x10 self-biasing amplifier" but without luck. BTW: How tight is your space? And what are you constraints regarding soldering? I'm pretty sure an opamp in an SC-70-5 with four 0402 resistors would do what you need, but might be a tad bit difficult to solder if you don't have the right equipment. Attila Kinali -- Reading can seriously damage your ignorance. -- unknown ___ 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] Need tiny 5MHz 10x amplifier
I would consider using a LVDS line receiver. http://www.digikey.com/catalog/en/partgroup/lvds-differential-line-receivers/11820 They are available in SOT-23 package, and can have built-in hysteresis, and 3.3V CMOS output. --- Graham == On Sat, Nov 28, 2015 at 6:35 PM, Poul-Henning Kamp wrote: > I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V > CMOS compatible logic signal. > > The "default" comparator based circuit either requires a negative > supply or 4 resitors for biasing the input and setting the zero level. > (The hysteresis resistor is the same in both cases). > > Since space is a bit tight, I've been trying to find something like > a "x10 self-biasing amplifier" but without luck. > > Any good ideas ? > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > ___ > 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] Need tiny 5MHz 10x amplifier
Moin, On Sun, 29 Nov 2015 00:35:31 + Poul-Henning Kamp wrote: > I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V > CMOS compatible logic signal. > > The "default" comparator based circuit either requires a negative > supply or 4 resitors for biasing the input and setting the zero level. > (The hysteresis resistor is the same in both cases). > > Since space is a bit tight, I've been trying to find something like > a "x10 self-biasing amplifier" but without luck. Ugh.. you are asking difficult stuff. 0.2Vpp is very little signal to work with. There are two options that come to my mind at this late hour. One would be to use an 74LVC14 with an series resistor at the input and one resistor from output back to the input. Kind of like an inverting ampilier. This because the hysteresis of the 74lvc14 is too large for the 0.2Vpp. But I admit this is a hack. For an one off system doable, but I wouldn't recommend it for anything build more than once. An alternative are fixed gain amplifiers, which do not need any feedback resistors and at times offer a pin with bias voltage. Ti has some of them[1]. I'm pretty sure others, like Maxim and Linear have them too. Attila Kinali [1] http://www.ti.com/lsds/ti/amplifiers-linear/fixed-gain-products.page -- Reading can seriously damage your ignorance. -- unknown ___ 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] Need tiny 5MHz 10x amplifier
On Sunday, November 29, 2015 12:35:31 AM Poul-Henning Kamp wrote: > I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V > CMOS compatible logic signal. > > The "default" comparator based circuit either requires a negative > supply or 4 resitors for biasing the input and setting the zero level. > (The hysteresis resistor is the same in both cases). > > Since space is a bit tight, I've been trying to find something like > a "x10 self-biasing amplifier" but without luck. > > Any good ideas LTC6957 ? requires input capacitor plus a bias bypass capacitor as well as a supply bypass capacitor. 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] Need tiny 5MHz 10x amplifier
The tl712cp works at 5 v and is self biased. Using one on the wwvb receiver to convert a 10 Mhz sine wave to square. 5V to 3.3 is pretty easy to convert. Maybe they make a 3.3V version. Paul WB8TSL On Sat, Nov 28, 2015 at 7:35 PM, Poul-Henning Kamp wrote: > I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V > CMOS compatible logic signal. > > The "default" comparator based circuit either requires a negative > supply or 4 resitors for biasing the input and setting the zero level. > (The hysteresis resistor is the same in both cases). > > Since space is a bit tight, I've been trying to find something like > a "x10 self-biasing amplifier" but without luck. > > Any good ideas ? > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > ___ > 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] Einstein Special on PBS
Hi Since you have massive doppler on the signals, it’s not practical to get frequency directly from the SV’s. All of our “frequency” information comes from time data extracted one way or the other from the signal. Either we do it directly from the broadcast data or indirectly from stuff like carrier phase comparisons. The quality of the time (and thus frequency) from GPS has gotten steadily better over the years. It is quite possible that they have added this or that to the steering process as things evolved. It clock tuning one of those things? Who knows… I suspect it is, but I have no real data to back up that guess. Bob > On Nov 28, 2015, at 12:05 PM, Mark Sims wrote: > > The GPS spec implies the satellites have a fixed frequency offset to > compensate for relativistic effects. But do they actually dynamically and/or > individually adjust the frequency to adjust for orbit variations and > eccentricities? > ___ > 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] Need tiny 5MHz 10x amplifier
I need to convert a 5MHz 0.2Vpp AC coupled sine signal to a 3.3V CMOS compatible logic signal. The "default" comparator based circuit either requires a negative supply or 4 resitors for biasing the input and setting the zero level. (The hysteresis resistor is the same in both cases). Since space is a bit tight, I've been trying to find something like a "x10 self-biasing amplifier" but without luck. Any good ideas ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Einstein Special on PBS
Hi, On 11/28/2015 06:05 PM, Mark Sims wrote: The GPS spec implies the satellites have a fixed frequency offset to compensate for relativistic effects. The spec actually points out that explicitly. This is the General Relativity shift due to different gravitational position of the satellites. But do they actually dynamically and/or individually adjust the frequency to adjust for orbit variations and eccentricities? No, this is what the user will have to do, as this depends on where the user receiver is, as these effects shift with place of observation of the orbit. For normal C/A-code receivers, this only turns out as the doppler shift, and once locked, the carrier control loop cancels it out and the pseudo-ranges only use the code-phase. Cheers, Magnus ___ 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] Einstein Special on PBS
Mark, The clocks themselves are not physically adjusted but numerical corrections (both clock and especially, orbit) for each satellite are updated as often as once every two hours. This is all part of the data stream that's sent down to the receiver. /tvb - Original Message - From: "Mark Sims" To: Sent: Saturday, November 28, 2015 9:05 AM Subject: [time-nuts] Einstein Special on PBS > The GPS spec implies the satellites have a fixed frequency offset to > compensate for relativistic effects. But do they actually dynamically and/or > individually adjust the frequency to adjust for orbit variations and > eccentricities? > ___ ___ 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] Einstein Special on PBS
The GPS spec implies the satellites have a fixed frequency offset to compensate for relativistic effects. But do they actually dynamically and/or individually adjust the frequency to adjust for orbit variations and eccentricities? ___ 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] Einstein Special on PBS
Hi ….but … As part of the time steering of the system, the ground segment constantly plays games with the total correction of each SV. Even with no offset, they still would bring it all into alignment. Yes it would be a major pain to do so with a “couple of mHz” error in the mix. I suspect that there are some pretty involved corrections that take care of just about anything that can be calculated. Bob > On Nov 28, 2015, at 5:16 AM, Magnus Danielson > wrote: > > The trouble is that they experience different acceleration, due to gravity, > and this yanks the experienced time. In the relativistic world, the concept > of time is not consistent between locations, and the effect of acceleration > between two locations shift it, and this is a consequence of a fixed speed of > light. This is the consequences of fixed speed of light, that the rate of > time needs to shift and this is the bizarreness of relativity that made many > physics initially not accept relativity. Over the 100 years, we have seen > again and again that this model actually makes sense for all the observations > we have. > > Elevating a clock from the earth, alters it's experienced gravitational > potential, the gravitational acceleration will be different. This is similar > to sending the clock towards us in a constant rate. Our experience of their > rate of time will be different, and so will they. Our gravitational > acceleration will from the top of the mountain look like sending us away from > them. For both cases the light speed is constant, so we can only yank the > rate of time, because the physics of the clocks at each such location does > not yank. > > Think of the oscillators being modeled as > > O1(t) = cos(2*pi*f0*T1(t)) > O2(t) = cos(2*pi*f0*T2(t)) > > T1(t) and T2(t) being local time functions. With the clocks at the same > location or otherwise similar locations, these will be about the same. The > physics of the clock sets f0. It's only when we change the characteristics > that alter T1 and T2 that we can observe that difference. The time t being > here some arbitrary non-observable time. > > Usually we get away with letting T1 and T2 be t directly, but the fixed speed > of light need us to alter these. > > If you now take two clocks of different physics (Cs and H-maser) and forms > two pairs. One that stays and one that goes to the top. Each pair will be > consistent, to the degree they are for normal systematics, but the mountain > pair will both experience the same shift compared to the valley pair. > > Cheers, > Magnus > > On 11/27/2015 07:10 PM, Mike Feher wrote: >> Bob - >> >> Thanks for attempting to make me see the light. But, I still do not. You >> said it yourself that hyperfine transitions remain the same. Since "time" on >> these device are derived from these transitions, they should also remain the >> same. I agree, from a relativistic point of vie the time will be different. >> I am just not convinced that using these types of clocks will demonstrate >> that. Thanks - 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 [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Stewart >> Sent: Friday, November 27, 2015 12:48 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Einstein Special on PBS >> >> Hi Mike, >> I'm far from an expert on this, but what you're missing is that time and >> space isn't the same between any two points that are located in different >> gravity gradients and/or moving at different relative velocities. The >> hyperfine transitions are happening at the same local rate whether the Cs >> device is on planet earth, in orbit around the earth, or in close proximity >> to the sun or even a black hole. But, all of these examples are happening >> in different space-time environments (i.e. different local frames), so that >> "relative" to each other, they are experiencing time at different rates. >> >> It might help to think of it in terms of doppler effect, though this is not >> an exact comparison. But, if you have two clocks that are moving away from >> each other, they may very well be precisely synchronous, but because of the >> doppler effect, any measurement you make will show them to be running at >> different rates. Because of the effects of gravity, watches at different >> altitudes appear to run at different rates to the outsider, although to the >> person wearing the watch, nothing has actually changed; it is the other >> person's watch that is acting funny. >> >> So, essentially, a clock sitting on the ground at sea level is running in a >> very slightly different space time than one that is sitting on a mountain. >> And when you place a clock in orbit, you also have 14,000 odd MPH of >> velocity that's also having an impact on the space-time of that o
Re: [time-nuts] Einstein Special on PBS
The trouble is that they experience different acceleration, due to gravity, and this yanks the experienced time. In the relativistic world, the concept of time is not consistent between locations, and the effect of acceleration between two locations shift it, and this is a consequence of a fixed speed of light. This is the consequences of fixed speed of light, that the rate of time needs to shift and this is the bizarreness of relativity that made many physics initially not accept relativity. Over the 100 years, we have seen again and again that this model actually makes sense for all the observations we have. Elevating a clock from the earth, alters it's experienced gravitational potential, the gravitational acceleration will be different. This is similar to sending the clock towards us in a constant rate. Our experience of their rate of time will be different, and so will they. Our gravitational acceleration will from the top of the mountain look like sending us away from them. For both cases the light speed is constant, so we can only yank the rate of time, because the physics of the clocks at each such location does not yank. Think of the oscillators being modeled as O1(t) = cos(2*pi*f0*T1(t)) O2(t) = cos(2*pi*f0*T2(t)) T1(t) and T2(t) being local time functions. With the clocks at the same location or otherwise similar locations, these will be about the same. The physics of the clock sets f0. It's only when we change the characteristics that alter T1 and T2 that we can observe that difference. The time t being here some arbitrary non-observable time. Usually we get away with letting T1 and T2 be t directly, but the fixed speed of light need us to alter these. If you now take two clocks of different physics (Cs and H-maser) and forms two pairs. One that stays and one that goes to the top. Each pair will be consistent, to the degree they are for normal systematics, but the mountain pair will both experience the same shift compared to the valley pair. Cheers, Magnus On 11/27/2015 07:10 PM, Mike Feher wrote: Bob - Thanks for attempting to make me see the light. But, I still do not. You said it yourself that hyperfine transitions remain the same. Since "time" on these device are derived from these transitions, they should also remain the same. I agree, from a relativistic point of vie the time will be different. I am just not convinced that using these types of clocks will demonstrate that. Thanks - 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 [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Stewart Sent: Friday, November 27, 2015 12:48 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Einstein Special on PBS Hi Mike, I'm far from an expert on this, but what you're missing is that time and space isn't the same between any two points that are located in different gravity gradients and/or moving at different relative velocities. The hyperfine transitions are happening at the same local rate whether the Cs device is on planet earth, in orbit around the earth, or in close proximity to the sun or even a black hole. But, all of these examples are happening in different space-time environments (i.e. different local frames), so that "relative" to each other, they are experiencing time at different rates. It might help to think of it in terms of doppler effect, though this is not an exact comparison. But, if you have two clocks that are moving away from each other, they may very well be precisely synchronous, but because of the doppler effect, any measurement you make will show them to be running at different rates. Because of the effects of gravity, watches at different altitudes appear to run at different rates to the outsider, although to the person wearing the watch, nothing has actually changed; it is the other person's watch that is acting funny. So, essentially, a clock sitting on the ground at sea level is running in a very slightly different space time than one that is sitting on a mountain. And when you place a clock in orbit, you also have 14,000 odd MPH of velocity that's also having an impact on the space-time of that object. As a result, when you bring the prodigal clock back to sea level, it will have experienced a slightly different amount of time than the one at sea level. Note that the prodigal clock hasn't run at a different rate. It has actually experienced time running at a different rate from that of the clock on the ground. Bob From: Mike Feher To: 'Discussion of precise time and frequency measurement' Sent: Friday, November 27, 2015 9:37 AM Subject: Re: [time-nuts] Einstein Special on PBS I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the trans
Re: [time-nuts] Einstein Special on PBS
Hi, On 11/27/2015 05:03 PM, Tom Van Baak wrote: They mentioned some "6 miles per day" offset due to GPS relativity effects. I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction? Hi Tim, Correct. Here's from the "rel" program (in my http://leapsecond.com/tools/ folder): C:\tvb\NPR>rel 2km 14000kph ** Altitude 2000.000 m (65616797.900 ft, 12427.424 mi) 5.274e-010 blueshift 1898630.424377 ps/hour 45567.130185 ns/day ** Velocity 3888.889 m/s (14000.000 km/h, 8699.197 mph) -8.414e-011 redshift -302888.070815 ps/hour -7269.313700 ns/day ** Net effect (GR+SR) 4.433e-010 shift 1595742.353562 ps/hour 38297.816485 ns/day What this means is that as a *source of UTC*, GPS would in fact be off by 38 us per day if you forgot about relativity when you designed it. But, you're right, you cannot blindly turn that "38 us/day" into "11 km/day". As long as *all* the GPS clocks are running too fast or too slow and as long as the receivers know what that offset is, the navigation system would still work just fine, relativity or not. This is true for any sort of triangulation (actually, trilateration) system. GPS is a PNT (Position, Navigation, and Timing) system. So while GPS is really cool, and relativity is really cool, the navigation part of GPS does not "depend" on relativity, per-se. As found in IS-GPS-200H: http://www.gps.gov/technical/icwg/IS-GPS-200H.pdf 8<--- 3.3.1.1 Frequency Plan. For Block IIA, IIR, IIR-M, and IIF satellites, the requirements specified in this IS shall pertain to the signal contained within two 20.46 MHz bands; one centered about the L1 nominal frequency and the other centered about the L2 nominal frequency (see Table 3-Vb). For GPS III and subsequent satellites, the requirements specified in this IS shall pertain to the signal contained within two 30.69 MHz bands; one centered about the L1 nominal frequency and the other centered about the L2 nominal frequency (see Table 3-Vc). The carrier frequencies for the L1 and L2 signals shall be coherently derived from a common frequency source within the SV. The nominal frequency of this source -- as it appears to an observer on the ground -- is 10.23 MHz. The SV carrier frequency and clock rates -- as they would appear to an observer located in the SV -- are offset to compensate for relativistic effects. The clock rates are offset by ∆ f/f = -4.4647E-10, equivalent to a change in the P-code chipping rate of 10.23 MHz offset by a ∆f = -4.5674E-3 Hz. This is equal to 10.229954326 MHz. The nominal carrier frequencies (f0) shall be 1575.42 MHz, and 1227.6 MHz for L1 and L2, respectively. --->8 There is however relativistic effects that the user equipment must compensate for, as it depends on the position of the user observation and shifts will be different for each user or for that matter for the user the shift will be different for each satellite. Cheers, Magnus ___ 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.
