[time-nuts] 10MHz LTE-Lite

Keith Loiselle keith.loiselle at gmail.com
Mon Dec 8 18:09:58 EST 2014

Enabling MEAN with 100 pts under Statistics should give an additional digit
but will take a few minutes for a reading with longer gate times.



On Mon, Dec 8, 2014 at 3:07 PM, Bob Camp <kb8tq at n1k.org> wrote:

> HI
> At a 1 second gate, your 5335 is good to about 1 ppb. (1x10^-9). A TCXO
> based GPSDO should be good to 10X that level. An OCXO based unit should be
> good to 100X that level.  If you extend the counter’s gate time, the 5335
> will overflow fairly quickly. Up to the point it does, it’s accuracy will
> improve directly with the gate time. Once it overflows, you can correct the
> result, but it is messy.
> Bob
> > On Dec 8, 2014, at 2:07 PM, Byron Hayes Jr <bhayes at earthlink.net> wrote:
> >
> > Time-Nuts Group,
> >
> > I thought some of you might be interested in my experience with the
> 10MHz LTE-Lite.
> >
> > The 10MHz LTE-Lite arrived about a week ago.  I was not ready to make a
> permanent installation, I wanted it portable and I wanted to get started
> quickly.  I am hobbyist interested mainly in the HF spectrum.  So I decided
> to operate the LTE-Lite inside the Priority Mail box, which was pretty much
> intact.  I cut a 5" X 8" piece of corrugated cardboard, mounted the unit on
> it with two doublestick pads, and put the cardboard with the unit into the
> Priority Mail box.  I cut a hole in the top of the box so I could see the
> LEDs, and cut three small holes in the side, one for the USB cable, one for
> the antenna wire and one for the 10 MHz output.  I attached the USB cable,
> antenna wire and 10 MHz output cable to the unit and ran them out of the
> box through the holes.  I had an operating Lenovo X220 Windows 7 computer
> near to the box, so I plugged the USB cable into the computer (I did not
> try to get or use any software on the computer to decipher any messages
> from the LTE-Lite).  I was in a
>  n upstairs North facing bedroom (in the Los Angeles area) so I put the
> antenna on a nearby windowsill.  I hooked the 10MHz output to the channel 1
> (Hi Z) input of my Tektronix 222A osciloscope, with the trigger on channel
> 1.
> >
> > When power was applied through the USB line, the LEDs seemed to light
> normally.  Within a couple of hours the lock LED was on, but the
> oscilloscope was showing noise, not a meaningful output.  I let the whole
> thing sit overnight, and the next day an apparent 10 MHz trace was on the
> screen.  It was not a sine wave, and not a square wave, but something in
> between.
> >
> > I had a small Rb unit, an Efratom 10 MHz FRS-C built into a TM-500
> plug-in.  I set that up and let it warm up and lock.  I connected the Rb
> output to channel 2 of the 222A and got that trace on the screen.  It was a
> sine wave basically in lock step with the LTE-Lite trace.  Over a few hours
> one could see slight relative movement, but very slight.  What next?
> >
> > I had a couple of HP 5300 series frequency counters, one a 5300B display
> with Option 1 (Hi-Stability time base) and a 5308B lower unit, and the
> other a plain 5300B display with a 5303B Option 1 (Hi-Stability time base)
> lower unit.  I give both time to warm up.  I put a "T" in the LTE-Lite
> output line and another "T" in the Rb output line, and connected coax from
> the Ts to the HiZ input of each frequency counter.  After they settled
> down, the counter connected to the LTE-Lite read 10000008 and the counter
> connected to the Rb read 10000002.  So, after a while, I reversed the leads
> to the counters, and the counter connected to the LTE-Lite read 10000002
> and the one conntected to the Rb read 10000008.  Those readings have been
> consistent for several days.  That indicated to me that the LTE-Lite and
> the Rb were both outputing essentially the same frequency, but the counters
> were a bit off (I had never calibrated these counters, since I wasn't sure
> of the accuracy of the Rb unit).  But,
>  I felt like the proverbial man with two watches.
> >
> > So, I brought out "Big Gonzo", a HP 5335A counter with Option 010
> (Hi-Stability time base) I purchased on eBay about six months ago but had
> never fired up.  It came up OK and I hooked it to the LTE-Lite output.  It
> initially read 10000028, but I gave it a couple of hours to warm up the
> oscillator oven and stabilize.  By then, the reading had settled to 10 000
> 000.  Now I switched cables and hooked the Rb to the 5335A, and it read 10
> 000 000.  I hooked the LTE-Lite to channel A of the 5335A and the Rb to
> channel B of the 5335A, and set the counter to "ratio".  When it settled,
> the counter read 1.000 000 indicating that the two outputs were the same
> frequency, at least to six decimals.  Apparently the 5335A is "right on".
> >
> > I conclude that both the LTE-Lite and the Rb are outputting a 10000000
> MHz signal.  I'm not sure of the accuracy beyond that.  They are probably
> both accurate enough for my purposes for calibrating other test equipment,
> receivers and transmitters operating in the HF spectrum.
> >
> > I would be interested in any comments or suggestions from other list
> members.
> >
> > Byron WA6ATN  _______________________________________________
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