Yes. I was not overly pleased with the performance of my 2700's. I ended up
pulling the PRS10 out of one of them and purchased the breakout connector board
from SRS and used the resulting 10 MHz and 1 PPS outputs. From time to time
I would sync the unit to one of my GPSDO's using the 1 PPS input.
I haven't powered up my 2700's in several years.
Your mileage may vary.
> On Dec 14, 2015, at 1:10 PM, Bob Camp <kb...@n1k.org> wrote:
>
> Hi
>
> One of the reasons the TS2700’s went out of favor is the “quality” of the
> CDMA signals
> available. The design assumption was that the CDMA carriers provided timing
> as good
> as GPS on their over the air systems. After the units had been in the field
> for a while it
> became apparent that the 2700’s were not performing up to expectations.
> Further investigation
> turned up a range of issues that degraded the CDMA timing relative to GPS. A
> lot of it
> boiled down to “we are a phone service not a time service”. System wise,
> CDMA gets
> into trouble at the 10us level. GPS is in trouble at the 100 ns level….
>
> Yes there are all sorts of rules and regulations. In the end it’s “this works
> fine” that trumps
> a lot of them.
>
> Bob
>
>> On Dec 14, 2015, at 1:15 PM, Charles Steinmetz <csteinm...@yandex.com> wrote:
>>
>> Tom wrote:
>>
>>> The 'unknown' is a Rubidium oscillator locked to CDMA pilot (TS2700)
>>
>> There is very little information publicly available on the Symmetricom
>> "BesTime" engine ("BTE"), but after playing with a few TS2700s for quite
>> some time, including monitoring a number of internal signals, several things
>> became apparent. First, the 2700 does not seem to discipline the PRS10.
>> The rubidium runs open loop and the BTE keeps track of the offset and the
>> drift rate from "BTE time" (which is synthesized from all available sources
>> -- however many CDMA signals it is receiving, plus any wireline telco timing
>> signals and the PRS10 -- using a proprietary algorithm to estimate the
>> reliability of each source and outputting BTE time and frequency using DDS).
>> Hobby users won't be feeding the unit any telco timing signals, so the BTE
>> has only the CDMA signals to work from. During holdover (and assuming no
>> telco timing signals), the Rb is the sole input to the BTE, which uses the
>> stored offset and drift to calculate BTE time.
>>
>> I found that the TS-2700 is more than an order of magnitude less stable than
>> a Trimble Thunderbolt, even with a full complement of rock-solid CDMA
>> sources. This may vary somewhat, depending on the CDMA equipment in use at
>> any particular location and the diligence of the CDMA operator.
>>
>> Best regards,
>>
>> Charles
>>
>>
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